SecProbe.io

CORRESP
 1
 filename1.htm

 CORRESP

 NUCANA PLC
 3 Lochside Way
 Edinburgh, EH12 9DT
 United Kingdom June 20, 2025
 VIA EDGAR U.S. Securities and Exchange Commission
 Division of Corporation Finance Office of Life Sciences
 100 F Street, N.E. Washington, D.C. 20549 Attention: Chris
Edwards

 Re:
 NuCana plc
 Registration Statement on Form F-3, as amended
 File No. 333-281576 (the “Registration Statement”)
 Acceleration Request Ladies and
Gentlemen: In accordance with Rule 461 of the Rules and Regulations promulgated under the Securities Act of 1933, as amended, NuCana plc (the
“Registrant”) hereby respectfully requests that the Securities and Exchange Commission accelerate the effective date of the above-referenced Registration Statement to Tuesday, June 24, 2025, at 4:00 p.m., Eastern Time, or as soon
as thereafter practicable. The cooperation of the staff in meeting the timetable described above is very much appreciated.
 Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., counsel to the Registrant, at (617)
 348-3050 with any questions regarding this request.

 Very truly yours,

 NUCANA PLC

 /s/ Hugh S. Griffith

 Hugh S. Griffith
 Chief Executive Officer

 cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
 John T. Rudy, Esq.

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 June 13, 2025

CERTIFIED MAIL
RETURN RECEIPT REQUESTED

Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom

 Re: NuCana plc
 Registration Statement on Form F-3
 Filed August 15, 2024
 File No. 333-281576
Dear Hugh S. Griffith:

 It has been more than nine months since you filed this registration
statement and it is
now out of date. Within 30 days from the date of this letter, you should
either:

 amend it to comply with the applicable requirements of the Securities Act
of 1933, the
 rules and regulations under the Act, and the requirements of the form; or
 file a request for withdrawal.
 If you requested confidential treatment for portions of any exhibits to
your registration
statement and you request withdrawal of that registration statement, please
submit a
concurrent request for withdrawal of your application for confidential
treatment.

 If you do not amend the registration statement or file a request for
withdrawal (or
provide us with a satisfactory explanation of why you have not done either)
within 30 days,
we may enter an order declaring the registration statement abandoned under rule
479 of the
Act.

 Please contact Chris Edwards at 202-551-6761 with any questions.

 Sincerely,
 June 13, 2025
Page 2

 Division of Corporation Finance
 Office of Life Sciences

cc: Corporation Service Company
 CERTIFIED MAIL
 RETURN RECEIPT REQUESTED
</TEXT>
</DOCUMENT>

CORRESP
 1
 filename1.htm

 CORRESP

 May 5, 2025
 VIA EDGAR U.S. Securities and Exchange
Commission Division of Corporation Finance 100 F Street,
N.E. Washington, D.C. 20549

 Re:
 NuCana plc
 Registration Statement on Form F-1, as amended
 File No. 333-286737
 Request for Acceleration of Effective Date
 Ladies and Gentlemen: Pursuant to Rule 461 of the General
Rules and Regulations under the Securities Act of 1933, as amended (the “ Securities Act ”), Laidlaw & Company (UK) Ltd., as placement agent, hereby joins in the request of NuCana plc for acceleration of the effective
date of the above-referenced registration statement on Form F-1, as amended (the “ Registration Statement ”), so that it becomes effective as of 5:00 p.m. Eastern Time on Monday,
May 5, 2025, or as soon thereafter as possible. Pursuant to Rule 460 of the General Rules and Regulations of the Securities Act, please be advised
that there will be distributed to each placement agent, who is reasonably anticipated to be invited to participate in the distribution of the security, as many copies of the proposed form of preliminary prospectus as appears to be reasonable to
secure adequate distribution of the preliminary prospectus. The undersigned has and will comply, and it has been informed or will be informed by any
participating dealers that they have complied or will comply, with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.
 [Signature Page to Follow]

 Very truly yours,

 LAIDLAW & COMPANY (UK) LTD.

 By:

 /s/ Luke Kottke

 Name:

 Luke Kottke

 Title:

 Head of Capital Markets
 [Signature Page to Placement Agent’s Acceleration Request]

CORRESP
 1
 filename1.htm

 CORRESP

 NUCANA PLC
 3 Lochside Way
 Edinburgh, EH12 9DT
 United Kingdom May 5, 2025
 VIA EDGAR U.S. Securities and Exchange Commission
 Division of Corporation Finance Office of Life Sciences
 100 F Street, N.E. Washington, D.C. 20549 Attention: Joshua
Gorsky and Tim Buchmiller

 Re:

 NuCana plc

 Registration Statement on Form F-1, as amended

 File No. 333-286716 (the “Registration Statement”)

 Acceleration Request
 Ladies and Gentlemen: In
accordance with Rule 461 of the Rules and Regulations promulgated under the Securities Act of 1933, as amended, NuCana plc (the “Registrant”) hereby respectfully requests that the Securities and Exchange Commission accelerate the effective
date of the above-referenced Registration Statement to Monday, May 5, 2025, at 5:00 p.m., Eastern Time, or as soon as thereafter practicable.
 The cooperation of the staff in meeting the timetable described above is very much appreciated.
 Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., counsel to the Registrant, at (617)
 348-3050 with any questions regarding this request.

 Very truly yours,

 NUCANA PLC

 /s/ Hugh S. Griffith

 Hugh S. Griffith
 Chief Executive Officer

 cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
 John T. Rudy, Esq.

CORRESP
 1
 filename1.htm

 CORRESP

 NUCANA PLC
 3 Lochside Way
 Edinburgh, EH12 9DT
 United Kingdom May 1, 2025
 VIA EDGAR U.S. Securities and Exchange Commission
 Division of Corporation Finance Office of Life Sciences
 100 F Street, N.E. Washington, D.C. 20549 Attention: Joshua
Gorsky and Tim Buchmiller

 Re:
 NuCana plc
 Registration Statement on Form F-1, as amended
 Filed April 29, 2025
 File No. 333-286716 (the “Registration Statement”)
 Withdrawal of Acceleration Request
 Ladies and Gentlemen: Reference is made to our letter, filed as
correspondence via EDGAR on April 29, 2025, in which we requested the acceleration of the effective date of the above-referenced Registration Statement for Wednesday, April 30, 2025 at 5:00 p.m., Eastern Time, in accordance with Rule 461
under the Securities Act of 1933, as amended. We are no longer requesting that such Registration Statement be declared effective at this time and we hereby formally withdraw our request for acceleration of the effective date.
 Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., counsel to the Registrant, at (617)
 348-3050 with any questions regarding this request.

 Very truly yours,

 NUCANA PLC

 /s/ Hugh S. Griffith

 Hugh S. Griffith Chief Executive
Officer

 cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
 John T. Rudy, Esq.

CORRESP
 1
 filename1.htm

 CORRESP

 May 1, 2025
 VIA EDGAR U.S. Securities and Exchange
Commission Division of Corporation Finance 100 F Street,
N.E. Washington, D.C. 20549

 Re:
 NuCana plc
 Registration Statement on Form F-1, as amended
 File No. 333-286737
 Withdrawal of Request for Acceleration of Effective Date
 Ladies and Gentlemen: Reference is made to our letter, filed as
correspondence via EDGAR on April 29, 2025, in which we requested the acceleration of the effective date of the above-referenced Registration Statement for Wednesday, April 30, 2025 at 5:00 p.m. Eastern Time, in accordance with Rule 461
under the Securities Act of 1933, as amended. We are no longer requesting that such Registration Statement be declared effective at this time and we hereby formally withdraw our request for acceleration of the effective date.
 [Signature Page to Follow]

 Very truly yours,

 LAIDLAW & COMPANY (UK) LTD.

 By:

 /s/ Luke Kottke

 Name:

 Luke Kottke

 Title:

 Head of Capital Markets
 [Signature Page to Placement Agent’s Withdrawal of Acceleration Request]

CORRESP
 1
 filename1.htm

 CORRESP

 April 29, 2025
 VIA EDGAR U.S. Securities and Exchange
Commission Division of Corporation Finance 100 F Street,
N.E. Washington, D.C. 20549

 Re:
 NuCana plc
 Registration Statement on Form F-1, as amended
 File No. 333-286737
 Request for Acceleration of Effective Date
 Ladies and Gentlemen: Pursuant to Rule 461 of the General
Rules and Regulations under the Securities Act of 1933, as amended (the “ Securities Act ”), Laidlaw & Company (UK) Ltd., as placement agent, hereby joins in the request of NuCana plc for acceleration of the effective
date of the above-referenced registration statement on Form F-1, as amended (the “ Registration Statement ”), so that it becomes effective as of 5:00 p.m. Eastern Time on Wednesday,
April 30, 2025, or as soon thereafter as possible. Pursuant to Rule 460 of the General Rules and Regulations of the Securities Act, please be
advised that there will be distributed to each placement agent, who is reasonably anticipated to be invited to participate in the distribution of the security, as many copies of the proposed form of preliminary prospectus as appears to be reasonable
to secure adequate distribution of the preliminary prospectus. The undersigned has and will comply, and it has been informed or will be informed by any
participating dealers that they have complied or will comply, with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.
 [Signature Page to Follow]

 Very truly yours,

 LAIDLAW & COMPANY (UK) LTD.

 By:

 /s/ Luke Kottke

 Name:

 Luke Kottke

 Title:

 Head of Capital Markets
 [Signature Page to Placement Agent’s Acceleration Request]

CORRESP
 1
 filename1.htm

 CORRESP

 NUCANA PLC
 3 Lochside Way
 Edinburgh, EH12 9DT
 United Kingdom April 29, 2025
 VIA EDGAR U.S. Securities and Exchange Commission
 Division of Corporation Finance Office of Life Sciences
 100 F Street, N.E. Washington, D.C. 20549 Attention: Joshua
Gorsky and Tim Buchmiller

 Re:
 NuCana plc
 Registration Statement on Form F-1, as amended
 Filed April 29, 2025
 File No. 333-286716 (the “Registration Statement”)
 Acceleration Request Ladies and
Gentlemen: In accordance with Rule 461 of the Rules and Regulations promulgated under the Securities Act of 1933, as amended, NuCana plc (the
“Registrant”) hereby respectfully requests that the Securities and Exchange Commission accelerate the effective date of the above-referenced Registration Statement to Wednesday, April 30, 2025, at 5:00 p.m., Eastern Time, or as
soon as thereafter practicable. The cooperation of the staff in meeting the timetable described above is very much appreciated.
 Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., counsel to the Registrant, at (617)
 348-3050 with any questions regarding this request.

 Very truly yours,

 NUCANA PLC

 /s/ Hugh S. Griffith

 Hugh S. Griffith
 Chief Executive Officer

 cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
 John T. Rudy, Esq.

CORRESP
 1
 filename1.htm

 CORRESP1

           

 One Financial Center
 Boston, MA 02111
 617 542 6000
 mintz.com
 April 29, 2025 VIA
EDGAR Securities and Exchange Commission Division
of Corporation Finance Office of Life Sciences 100 F
Street, N.E. Washington, D.C. 20549 Attention: Joshua Gorsky and Tim Buchmiller

 Re:

  

 NuCana plc Registration
Statement on Form F-1 Filed on April 24, 2025
 CIK No. 0001709626
 Ladies and Gentlemen: We are
submitting this letter on behalf of NuCana plc (the “ Company ”) in response to the comments from the staff (the “ Staff ”) of the U.S. Securities and Exchange Commission (the “ Commission ”) received by
letter dated April 24, 2025 (the “ Comment Letter ”) from the Division of Corporation Finance, Office of Life Sciences, to Hugh S. Griffith, Chief Executive Officer of the Company, relating to the above-referenced Registration
Statement on Form F-1. In conjunction with this letter, the Company is filing an Amended Registration Statement on Form F-1 with the Commission (the “ Amended
 Form F-1 ”). For reference, we have set forth below in italics the Staff’s comments from the
Comment Letter and have keyed the Company’s responses to the numbering of the comments and the headings used in the Comment Letter. Where appropriate, the Company has responded to the Staff’s comments by making changes to the disclosure in
the Amended Form F-1. Page numbers referred to in the responses reference the applicable pages of Amended Form F-1.
 Registration Statement on Form F-1
 Cover Page Comment 1 : Please revise your cover
page to disclose the date your best efforts offering will terminate. Refer to Item 501(b)(8)(iii) of Regulation S-K for guidance.
 Response 1 : The Company respectfully acknowledges the Staff’s comment and has revised this disclosure on the cover page narrative of the Amended
Form F-1 in accordance with the Staff’s comment. Comment 2 : We note your response to prior comment
2 and your revised disclosure stating that “Mandatory Nominal Exercise Price” is “the nominal value per ordinary share.” We reissue our comment in part. Please clearly disclose the dollar value of the Mandatory
Nominal Exercise Price. Response 2 : The Company respectfully acknowledges the Staff’s comment and has revised this disclosure on the cover
page narrative of the Amended Form F-1 in accordance with the Staff’s comment.

 BOSTON LOS ANGELES MIAMI NEW YORK SAN DIEGO SAN FRANCISCO TORONTO WASHINGTON
 MINTZ, LEVIN, COHN, FERRIS, GLOVSKY AND POPEO, P.C.

 April 29, 2025
 Page
 2

 Risk Factors
 Risks Related to This Offering This offering may cause
the price of our ADSs to decline and fall below the minimum bid price requirement..., page 11
 Comment 3 : We note your response to prior comment 4 and your revised disclosure on page 11 stating that if the closing price for your ADSs falls
below $1.00 for a 30 consecutive trading day period and you are unable to regain compliance with the bid price requirement of the Nasdaq Listing Rules, you may be delisted from the Nasdaq Capital Market unless you “change the
ratio of [y]our ADSs to ordinary shares[.]” We reissue our comment in part. Please revise your disclosure to clarify whether you have plans to seek shareholder approval for a reverse stock split or have plans to increase the
number of ordinary shares represented by your ADSs, please disclose such plans in this registration statement, including the proposed ratio, if known.
 Response 3 : The Company respectfully acknowledges the Staff’s comment and has revised the risk factor on page 12 of the Amended Form F-1 in accordance with the Staff’s comment.
 *  *  *  *  *
 We hope that the above response will be acceptable to the Staff. Please do not hesitate to call me at (617) 348-3050
with any comments or questions regarding the proposed disclosure. We thank you for your time and attention.

 Sincerely,

 /s/ John T. Rudy

 John T. Rudy

 cc:

   

 NuCana plc Hugh S.
Griffith Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
 William C. Hicks John T. Rudy
 Allyson Wilkinson

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 April 24, 2025

Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom

 Re: NuCana plc
 Registration Statement on Form F-1
 Filed April 24, 2025
 File No. 333-286716
Dear Hugh S. Griffith:

 We have reviewed your amended registration statement and have the
following
comments.

 Please respond to this letter by amending your registration statement
and providing
the requested information. If you do not believe a comment applies to your
facts and
circumstances or do not believe an amendment is appropriate, please tell us why
in your
response.

 After reviewing any amendment to your registration statement and the
information
you provide in response to this letter, we may have additional comments. Unless
we note
otherwise, any references to prior comments are to comments in our April 17,
2025 letter.

Registration Statement on Form F-1
Cover Page

1. Please revise your cover page to disclose the date your best efforts
offering will
 terminate. Refer to Item 501(b)(8)(iii) of Regulation S-K for guidance.
2. We note your response to prior comment 2 and your revised disclosure
stating that
 "Mandatory Nominal Exercise Price" is "the nominal value per ordinary
share." We
 reissue our comment in part. Please clearly disclose the dollar value of
the Mandatory
 Nominal Exercise Price.
 April 24, 2025
Page 2
Risk Factors
Risks Related to This Offering
This offering may cause the price of our ADSs to decline and fall below the
minimum bid
price requirement..., page 11

3. We note your response to prior comment 4 and your revised disclosure on
page 11
 stating that if the closing price for your ADSs falls below $1.00 for a
30 consecutive
 trading day period and you are unable to regain compliance with the bid
price
 requirement of the Nasdaq Listing Rules, you may be delisted from the
Nasdaq
 Capital Market unless you "change the ratio of [y]our ADSs to ordinary
shares[.]" We
 reissue our comment in part. Please revise your disclosure to clarify
whether you have
 plans to seek shareholder approval for a reverse stock split or have
plans to increase
 the number of ordinary shares represented by your ADSs, please disclose
such plans
 in this registration statement, including the proposed ratio, if known.

 Please contact Joshua Gorsky at 202-551-7836 or Tim Buchmiller at
202-551-3635
with any other questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: John T. Rudy, Esq.
</TEXT>
</DOCUMENT>

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 April 17, 2025

Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom

 Re: NuCana plc
 Draft Registration Statement on Form F-1
 Submitted April 4, 2025
 CIK No. 0001709626
Dear Hugh S. Griffith:

 We have conducted a limited review of your draft registration statement
and have the
following comments.

 Please respond to this letter by providing any requested information
and by publicly
filing your registration statement and non-public draft submission on EDGAR. If
you do not
believe a comment applies to your facts and circumstances or do not believe an
amendment is
appropriate, please tell us why in your response.

 After reviewing the information you provide in response to this letter
and your filed
registration statement, we may have additional comments.

Draft Registration Statement on Form F-1
Cover Page

1. We note your disclosure on page 10 that the Series A Warrants and Series
B Warrants
 contain reset provisions that may result in a downward adjustment to the
exercise
 price of such warrants, and that may result in a corresponding increase
to the number
 of ADSs issuable upon the exercise of such warrants, and that,
additionally, if the
 Series B Warrants are exercised by way of an "alternative cashless
exercise," such
 exercising holder will receive three ADSs for each ADS they would
receive in a cash
 exercise for the Series B Warrants they exercise, without any cash
payment to the
 company (subject to the mandatory nominal exercise price). Please revise
the cover
 page headings, the cover page narrative and the Prospectus Summary to
highlight the
 maximum number of ADSs that could be issued upon the exercise of your
Series A
 April 17, 2025
Page 2

 Warrants and Series B Warrants, and, if similar formulas apply, the
Pre-Funded
 Warrants. For guidance, refer to Regulation S-K Item 501(b)(2).
Additionally, as
 appropriate for each of the respective warrants, disclose that the
number of ADSs
 issuable upon the exercise of such warrants increases as the stock price
falls further
 below the initial exercise price of such warrants.
2. With respect to the "alternative cashless exercise" feature of the
Series B Warrants,
 please revise the cover page narrative and Prospectus Summary to
explain, if true, that
 as a result of this feature you do not expect to receive any cash
proceeds from the
 exercise of those warrants because it is highly unlikely that a warrant
holder would
 wish to pay an exercise price to receive one ADS when they could choose
the
 "alternative cashless exercise" option and pay no money, except for the
mandatory
 nominal exercise price, to receive three ADSs. Additionally, please
include in your
 disclosure, where appropriate, the value of the "mandatory nominal
exercise price"
 referenced on page 10.
Risk Factors
Risks Related to This Offering
We are selling a substantial number of ADSs in this offering, which could cause
the price of
our ADSs to decline., page 9

3. We note your risk factor disclosure on page 10 that the Series A
Warrants and the
 Series B Warrants contain exercise price adjustments, adjustments to
increase the
 number of ADSs "issuable" upon exercise, and, in the case of the Series
B Warrants,
 an "alternative cashless exercise" feature, which, if triggered, may
cause substantial
 dilution. Please revise the risk factor disclosure, or add a new risk
factor, to address
 potential dilution from the reset provisions that could adjust upward
the number of
 ADSs underlying the Series A Warrants and the Series B Warrants and from
the
 "alternative cashless exercise" feature of the Series B Warrants. The
risk factor should
 disclose the maximum number of ADSs that may be issuable upon exercise
of all of
 the Warrants.
4. Please include a risk factor stating, if true, that this offering could
cause the price of
 your ADSs to fall below the minimum bid price required by the Nasdaq
Listing Rules,
 which could result in your ADSs being delisted from Nasdaq. To the
extent you have
 plans to seek shareholder approval for a reverse stock split or have
plans to increase
 the number of ordinary shares represented by your ADSs, please disclose
such plans
 in this registration statement, including the proposed ratio, if known.
General

5. We note your references in your prospectus to an "alternative cashless
exercise" of the
 Series B Warrants. The term "cashless exercise" is generally understood
to allow a
 warrant holder to exercise a warrant without paying cash for the
exercise price and
 reducing the number of shares receivable by the holder by an amount
equal in value to
 the aggregate exercise price the holder would otherwise pay to exercise
the warrants.
 In cashless exercises, it is expected that the warrant holder receives
fewer shares than
 they would if they opted to pay the exercise price in cash. Please
clarify your
 disclosure throughout the prospectus by removing the references to
"alternative
 April 17, 2025
Page 3

 cashless exercise" and exclusively using the term "zero exercise price"
or another
 appropriate term that conveys that, in addition to the company receiving
no, or
 nominal, cash upon the "alternative cashless exercise," the warrant
holders would be
 entitled to receive more ADSs than they would under the cash exercise
terms.
 We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence
of action by the staff.

 We also remind you that your registration statement must be on file at
least two
business days prior to the requested effective date and time. Refer to Rules
460 and 461
regarding requests for acceleration. Please allow adequate time for us to
review any
amendment prior to the requested effective date of the registration statement.

 Please contact Joshua Gorsky at 202-551-7836 or Tim Buchmiller at
202-551-3635
with any other questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: John T. Rudy, Esq.
</TEXT>
</DOCUMENT>

August 16, 2024
Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom
Re:NuCana plc
Registration Statement on Form F-3
Filed August 15, 2024
File No. 333-281576
Dear Hugh S. Griffith:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration. We remind you that
the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Chris Edwards at 202-551-6761 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:John T. Rudy, Esq.

United States securities and exchange commission logo
August 25, 2021
Hugh Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom
Re:NuCana plc
Registration Statement on Form F-3
Filed August 19, 2021
File No. 333-258941
Dear Mr. Griffith:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Gary Guttenberg at (202) 551-6477 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       John Rudy

CORRESP
1
filename1.htm

CORRESP

 NUCANA PLC

3 Lochside Way

Edinburgh, EH12 9DT

United Kingdom

 August 25, 2021

VIA EDGAR

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

 Attention:
    Mr. Guttenberg

Re:
 NuCana plc

Registration Statement on Form F-3

Filed August 19, 2021

File No. 333-258941 (the “Registration Statement”)

Acceleration Request

 Ladies and
Gentlemen:

 In accordance with Rule 461 of the Rules and Regulations promulgated under the Securities Act of 1933, as amended, NuCana plc (the
“Registrant”) hereby respectfully requests that the Securities and Exchange Commission accelerate the effective date of the above-referenced Registration Statement to Friday, August 27, 2021, at 4:00 p.m., Eastern Time, or as soon as
thereafter practicable.

 The cooperation of the staff in meeting the timetable described above is very much appreciated.

Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., counsel to the Registrant, at (617)
348-3050 with any questions regarding this request.

Very truly yours,

NUCANA PLC

/s/ Donald Munoz

 Donald Munoz

 Chief Financial
Officer

cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

 John T. Rudy, Esq.

CORRESP
1
filename1.htm

Acceleration Request

 NUCANA PLC

3 Lochside Way

 Edinburgh, EH12 9DT

United Kingdom

 October 18, 2018

VIA EDGAR

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

 Attention:    Ms. Irene Paik

Re:
 NuCana plc

 Registration Statement on Form F-3

 Filed October 1, 2018

 File No. 333-227624 (the “Registration Statement”)

 Acceleration Request

Ladies and Gentlemen:

 In accordance with Rule 461 of the Rules and
Regulations promulgated under the Securities Act of 1933, as amended, NuCana plc (the “Registrant”) hereby respectfully requests that the Securities and Exchange Commission accelerate the effective date of the above-referenced
Registration Statement to Monday, October 22, 2018, at 12:00 p.m., Eastern Time, or as soon as thereafter practicable.

 The cooperation of the staff in
meeting the timetable described above is very much appreciated.

 Please contact John T. Rudy of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.,
counsel to the Registrant, at (617) 348-3050 with any questions regarding this request.

Very truly yours,

NUCANA PLC

/s/ Donald Munoz

 Donald Munoz

 Chief Financial Officer

cc:
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

 John T. Rudy, Esq.

October 9, 2018
Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom
Re:NuCana plc
Registration Statement on Form F-3
Filed October 1, 2018
File No. 333-227624
Dear Mr. Griffith:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Irene Paik at 202-551-6553 with any questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       John T. Rudy, Esq.

CORRESP
1
filename1.htm

CORRESP

 September 25, 2017

 VIA EDGAR

 United States Securities and Exchange Commission

100 F Street, NE

 Washington, D.C. 20549

Attention:

Keira Nakada

Kenneth Vaughn

Jeffrey Gabor

Mary Beth Breslin

Re:

NuCana plc

Registration Statement on Form F-1

File No. 333-220321

Request for Acceleration

Ladies and Gentlemen:

In accordance with Rule 461 of the General Rules and Regulations under the Securities Act of 1933, as amended, NuCana plc (the
“Registrant”) hereby requests that the effectiveness of the above-referenced Registration Statement on Form F-1, as amended (the “Registration Statement”), be accelerated
so that it will be declared effective at 4:00 p.m. Eastern time on September 27, 2017, or as soon thereafter as practicable, or at such later time as the Registrant or its counsel may request via telephone call to the staff. Once the
Registration Statement has been declared effective, please orally confirm that event with our counsel, Mintz, Levin, Cohn, Ferris, Glovsky and Popeo P.C., by calling John T. Rudy at (617) 348-3050 or Adam
Davey at (617) 348-1667 to provide notice of effectiveness, or if you have any other questions or concerns regarding this matter.

 It is the registrant’s understanding that its
registration of the American Depositary Shares of the registrant under the Securities Exchange Act of 1934 on Form 8-A (File No. 001-38215) shall automatically become effective upon the later of the Securities and Exchange Commission’s receipt
of certification from The NASDAQ Stock Market LLC with respect to the American Depositary Shares of the registrant and the effectiveness of the Registration Statement.

 [Signature page follows]

 Very truly yours,

 NuCana plc

 By:

 /s/ Hugh S. Griffith

 Name: Hugh S. Griffith

 Title:   Chief Executive Officer

CORRESP
1
filename1.htm

CORRESP

 September 25, 2017

VIA EDGAR

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 100 F Street,
N.E.

 Washington, D.C. 20549

 Attn: Suzanne Hayes

Re:

NuCana plc (the “Company”)

 Registration Statement on Form F-1 (File
No. 333-220321)

 Dear Ms. Hayes:

In accordance with Rule 461 under the Rules and Regulations of the Securities and Exchange Commission under the Securities Act of 1933, as
amended (the “Securities Act”) and as representatives of the several underwriters of the Company’s proposed initial public offering of American Depositary Shares, representing the Company’s ordinary shares, we
hereby join in the Company’s request that the effectiveness of the above-referenced Registration Statement, as amended, be accelerated to 4:00 p.m. Eastern Daylight Time, on Wednesday, September 27, 2017, or as soon thereafter as
practicable, or at such later time as the Company may orally request.

 Pursuant to Rule 460 under the Securities Act, we wish to advise
you that between September 18, 2017 and the date hereof, approximately 695 copies of the Preliminary Prospectus dated September 18, 2017 were distributed to prospective underwriters, institutional investors, prospective dealers,
individuals and others.

 We wish to advise you that the undersigned, as representatives of the several underwriters, have complied and
will continue to comply, and we have been informed by the participating underwriters that they have complied and will continue to comply, with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.

[Signature Page Follows]

 Very truly yours,

Citigroup Global Markets Inc.

 Jefferies LLC

Cowen and Company, LLC

 As Representatives of the
several Underwriters

CITIGROUP GLOBAL MARKETS INC.

By:

/s/ Rizwan Velji

Name: Rizwan Velji

Title: Director

JEFFERIES LLC

By:

/s/ Matthew Kim

Name: Matthew Kim

Title: Managing Director

COWEN AND COMPANY, LLC

By:

/s/ George Milstein

Name: George Milstein

Title: Managing Director

 [Signature Page to NuCana plc Acceleration Request]

September 19, 2017
Hugh S. Griffith
Chief Executive Officer
NuCana plc
10 Lochside Place
Edinburgh, EH12 9RG
United Kingdom
NuCana plc
Amendment No. 1 to Form F-1
Filed September 18, 2017
File No. 333-220321Re:
Dear Mr. Griffith:
We have reviewed your amended registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we may
better understand your disclosure.
Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comments apply to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
After reviewing any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Amendment No. 1 to Form F-1 filed September 18, 2017
Exhibits
1. Counsel must examine all matters necessary to render its opinion pursuant to Section
601(b)(5) of Regulation S-K. As such, please file an opinion that does not include the
qualification in paragraphs 5.1.1 or 5.1.5 of Exhibit 5.1 and that otherwise makes clear
that counsel has reviewed all matters and made such inquiries as are necessary to render
its opinion.
2. Please file an opinion of counsel that does not include the limitation in paragraph 6.1 of
Exhibit 5.1.  In the alternative, please explain how the limitation is consistent with
Section 14 of the Securities Act.

Hugh S. Griffith
NuCana plc
September 19, 2017
Page 2

3. We note that the opinion filed as Exhibit 5.1 is addressed in paragraph 7.1 to the company
"solely" for its benefit in connection with the registration statement.  Please file a revised
opinion of counsel that does not limit shareholders' reliance on the opinion.
You may contact Keira Nakada at 202-551-3659 or Kevin Vaughn at 202-551-3494 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Mary Beth Breslin at 202-551-3625 with any other questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc: Adam Davey, Esq.

CORRESP
1
filename1.htm

CORRESP

 September 12, 2017

 VIA EDGAR & HAND DELIVERY

 Securities and Exchange Commission

 Division of Corporation Finance

100 F Street, N.E. Washington, D.C. 20549

Attention: Division of Corporation Finance, Office of Healthcare and Insurance

 Re: NuCana plc (formerly NuCana BioMed Limited)

 Registration Statement on Form F-1 (File No. 333-220321)

Filed September 1, 2017

 CIK No. 0001709626

 Ladies and Gentlemen:

 We are submitting this letter on behalf of NuCana plc (formerly NuCana BioMed Limited) (the “Company”) in response to comments from the staff of the Division of Corporation Finance,
Office of Healthcare and Insurance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) conveyed in a telephone conversation with the undersigned on September 12, 2017, relating to the
above-referenced Registration Statement.

 Per the
Staff’s request conveyed in the telephone conversation referenced above, and in further response to Comment 1 in the letter from the Staff dated August 16, 2017 as previously responded to by the Company in its response letter to the
Staff dated September 1, 2017, the Company is supplementally submitting to the Staff the Company’s proposed revisions to “Summary—Overview” on page 1 of the Registration Statement and to “Risk Factors—Risks
Related to Development of Our Product Candidates—Initial success in the completed and ongoing early-stage clinical trials may not be indicative of results obtained when these trials are completed or in later stage trials” on page 18
of the Registration Statement. Those proposed revisions are attached hereto as Exhibit A, marked against the existing disclosure in the Registration Statement as filed on September 1, 2017. We are providing by hand delivery to your
attention five courtesy copies of this letter, including Exhibit A.

 We hope that the proposed revisions reflected in Exhibit A will be acceptable to the Staff. Please do not hesitate to call me, William C. Hicks, William T. Whelan or Adam Davey of
this firm at (617) 542-6000 with any comments or questions regarding the Registration Statement and this letter. We thank you for your time and attention.

 Sincerely,

 /s/ John T. Rudy

 John T. Rudy

 Mintz, Levin, Cohn,
Ferris, Glovsky and Popeo, P.C.

 September 12, 2017

 Page 2

cc:

Securities and Exchange Commission

Keira Nakada

Kenneth Vaughn

Jeffrey Gabor

Mary Beth Breslin

NuCana plc

Hugh S. Griffith

Donald Munoz

Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

William C. Hicks

William T. Whelan

Adam Davey

Cooley LLP

Divakar Gupta

Brent B. Siler

Courtney T. Thorne

 EXHIBIT A

 NuCana plc Registration Statement on Form F-1 (File
No. 333-220321), filed September 1, 2017

Summary – Overview (pages 1-2)

We are a clinical-stage biopharmaceutical company focused on significantly improving treatment outcomes for cancer
patients by applying our ProTide™ technology to transform some of the most widely prescribed chemotherapy agents, nucleoside analogs, into more effective and safer medicines. While these conventional agents remain part of the standard of care
for the treatment of many solid tumors, their efficacy is limited by cancer cell resistance mechanisms and they are often poorly tolerated. Utilizing our proprietary technology, we are developing new medicines, ProTides, designed to overcome key
cancer resistance mechanisms and generate much higher concentrations of anti-cancer metabolites in cancer cells. Our most advanced ProTide candidates, Acelarin® and NUC-3373, are new chemical entities derived from the nucleoside analogs gemcitabine and 5-fluorouracil, respectively, two
widely used chemotherapy agents. Acelarin is currently being evaluated in four clinical trials across several solid tumor indications, including ovarian cancer, biliary cancer and pancreatic cancer. NUC-3373
is currently in a Phase 1 trial for the potential treatment of a wide range of advanced solid tumor cancers. We have retained worldwide rights to these lead product candidates as well as our preclinical product candidates, all of which we refer
to as ProTides.

 Acelarin, our most advanced
product candidate, is a potential first-in-class ProTide that has been evaluated in over 130 patients. Acelarin is a ProTide transformation of gemcitabine that we believe could replace gemcitabine in certain cancer indications and have utility
across a range of other cancers. In a Phase 1 dose-ranging trial in 49 evaluable patients with advanced metastatic solid tumors, Acelarin was well tolerated, achieved a high78% disease control rate and was associated
with intracellular levels of active anti-cancer metabolite over 200 times higher than those reported for gemcitabine. A subset of 14 evaluable patients with relapsed/refractory gynecological cancers achieved a high93% disease
control rate. In a Phase 1b dose-ranging trial in 23 evaluable patients with recurrent ovarian cancer, Acelarin was combined with carboplatin and achieved a high96% disease control rate. As these results were
obtained in first-in-human dose-ranging trials, they are not suitable for marketing approval. However, based on the encouragingBased on these disease control rates and theits tolerability profile, we have
begun a Phase 2 trial of Acelarin in patients with platinum-resistant ovarian cancer, for which we expect to report interim data in 2018. Acelarin is also being evaluated in another Phase 1b trial in patients with biliary cancer to determine its
optimal dose in combination with cisplatin. We expect to report data from this trial in 2018, after which we plan to commence a multi-national Phase 3 trial. In addition, the National Cancer Research Institute in the United Kingdom is
facilitating a Phase 3 trial of Acelarin for the treatment of patients with pancreatic cancer. The disease control rates referred to above include complete responses, partial responses and stable disease, measured by radiographic assessment
to determine changes in tumor size, and evaluated using the standard scoring system known as Response Evaluation Criteria in Solid Tumors, or RECIST. The disease control rates are based on investigator assessment of tumor response in a limited
number of patients and may not be predictive of or consistent with the results of later trials.

NUC-3373, our second product candidate, is a ProTide transformation of the active anti-cancer
metabolite of 5-fluorouracil, or 5-FU, which we believe has the potential to replace 5-FU as the standard of care in the
treatment of a wide range of cancers. In preclinical studies, we observed that NUC-3373 overcame the key resistance mechanisms associated with 5-FU and generated intracellular levels of active anti-cancer
metabolite over 300 times higher than that of 5-FU. NUC-3373 is currently being evaluated in a Phase 1 clinical trial of patients with advanced solid tumors and we
expect to report interim data from this trial in the second half of 2017. Contingent on regulatory guidance and other factors, we plan to initiate a number of clinical trials in 2018: a Phase 1b trial of
NUC-3373 in patients with colorectal cancer together with other agents routinely used in 5-FU combination regimens; a Phase 3 trial in patients with advanced
colorectal cancer; and a Phase 2 trial in patients with advanced breast cancer.

 NUC-7738, our third product candidate, is a ProTide
transformation of cordycepin, a novel nucleoside analog that has shown potent anti-cancer activity in preclinical studies. We are evaluating NUC-7738 in preclinical studies and we expect to initiate a
Phase 1 clinical trial in 2018.

 Despite the
widespread use of nucleoside analogs, their efficacy is severely limited by cancer cell resistance mechanisms and they are often poorly tolerated. Harnessing the power of phosphoramidate chemistry, we convert nucleoside analogs into activated
nucleotide analogs with the addition of a phosphate group, which is protected by specific combinations of aryl, ester and amino acid groupings. By adding and protecting this phosphate group, we design our ProTides to avoid or overcome key cancer
resistance mechanisms in the uptake, activation and breakdown of nucleoside analogs. As a result, we believe our ProTides have the potential to generate hundreds of times higher concentrations of the active anti-cancer metabolites inside tumor
cells, potentially making our ProTides more effective than the current standards of care. Because our ProTides resist breakdown, and are thus more stable, we believe they are also able to reduce or eliminate the generation of toxic byproducts that
can result from the breakdown of nucleoside analogs like gemcitabine and 5-FU.

Our proprietary ProTide technology was invented in the Cardiff University laboratory of our late Chief Scientific Officer, Professor
Christopher McGuigan, who conceived of, and filed the original composition of matter patents for our initial ProTides. The unique feature of his discovery was the specific combination of aryl, ester and amino acid groupings that protect the
activated, or phosphorylated, nucleoside analog. This phosphoramidate chemistry approach is the key to the ProTide technology. Every ProTide grouping is distinct, and Professor McGuigan and his team synthesized and tested thousands of compounds in
order to identify the optimal ProTide grouping for each underlying nucleoside analog.

We have licensed what we believe to be the foundational patent estate for the application of phosphoramidate
chemistry in oncology. We have granted patents in key markets, including the United States, Europe and Japan, protecting the composition of matter of Acelarin, NUC-3373 and other of our product candidates.
Professor McGuigan’s work preceded and helped lead to the development of several FDA-approved anti-viral drugs containing nucleotide analogs, including: sofosbuvir, or Sovaldi®, which is also a key component of
Harvoni®; and tenofovir alafenamide fumarate, or TAF, which is a key component of Genvoya®, Descovy® and Odefsey®.

 We are led by Hugh S. Griffith, our founder and Chief
Executive Officer, who brings over 25 years of experience in the biopharmaceutical industry, including at Abbott Laboratories (now AbbVie Inc.) and Parke-Davis Warner Lambert (now Pfizer Inc.). Before founding NuCana, he led the operations of
Bioenvision, Inc. from start-up through its acquisition by Genzyme Corporation. While at Bioenvision, he was instrumental in developing and commercializing clofarabine, a nucleoside analog for the treatment of pediatric leukemia. We are backed by
leading life sciences investors, including Sofinnova Partners, Sofinnova Ventures, Morningside Group and Scottish Enterprise.

 Risk Factors – Risks Related to Development of Our Product Candidates (p. 18)

 Initial success in the completed and ongoing early-stage clinical
trials may not be indicative of results obtained when these trials are completed or in later stage trials.

 Acelarin is currently being evaluated in four clinical trials across numerous solid tumor indications: one Phase 1b trial in combination with cisplatin in patients with biliary cancer, one Phase 1b
trial in patients with platinum-sensitive ovarian cancer, one Phase 2 trial in patients with recurrent ovarian cancer, and one multi-year investigator-sponsored Phase 3 trial in patients with pancreatic cancer. While Acelarin has shown
high disease control rates and a favorable tolerability profile in early-stage trials, including in two first-in-human dose-ranging Phase 1 trials, we may not see such favorable data in future clinical trials involving Acelarin. Similarly,
favorable results obtained from preclinical studies of NUC-3373 and in the ongoing Phase 1 trial in patients with advanced solid tumors may not be replicated in any future clinical trials.
DataIn addition, data generated in these early stage Phase 1 trials are not suitable forthe basis on which marketing approval by the FDA or a comparable foreign regulatory authority would be
sought. Furthermore, the results of our clinical trials may not meet the level of statistical significance required by the FDA or comparable foreign regulatory authorities for marketing approval. Statistical significance means that an effect is
unlikely to have occurred by chance. Clinical trial results are considered statistically significant when the probability of the results occurring by chance, rather than from the efficacy of the product candidate, is sufficiently low. There can be
no assurance that any of our clinical trials will ultimately be successful or support further clinical development of any of our product candidates. There is a high failure rate for drugs proceeding through clinical trials. A number of companies in
the pharmaceutical and biotechnology industries have suffered significant setbacks in clinical development even after achieving promising results in earlier studies.

September 12, 2017
Hugh S. Griffith
Chief Executive Officer
NuCana plc
10 Lochside Place
Edinburgh, EH12 9RG
United Kingdom
NuCana plc
Registration Statement on Form F-1
Filed September 1, 2017
File No. 333-220321Re:
Dear Mr. Griffith:
We have reviewed your registration statement and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.
Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comments apply to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
After reviewing any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Form F-1 filed 09/01/2017
Notes to the Unaudited Consolidated Interim Financial Statements
10.  Share Capital and Share Premium, page F-11
1. We note your adjustment of £42.5 million from share premium to retained earnings as a
result of the execution of the solvency statement on June 29, 2017.  Tell us how you
considered reporting the amounts in question in a separate line item outside of retained
earnings, given that the £42.5 million does not represent an accumulation of historical
earnings.

Hugh S. Griffith
NuCana plc
September 12, 2017
Page 2

Notes to the Consolidated Financial Statements
2.  Significant Accounting Policies
Intangible Assets, page F-20
2. We continue to believe you have not adequately demonstrated that the pattern of expected
consumption of the economic benefits of the patents in question can be reliably estimated
to match the pattern of the reverse sum-of-the-years-digits amortization methodology you
have selected.  However, based on your assertion that the amortization expense amounts
under the reverse sum-of-the-years digits methodology for these patents is not materially
different from the amounts under the straight-line amortization method for the periods
presented, we do not object to the amounts presented as amortization expense for these
periods.
We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
Refer to Rules 460 and 461 regarding requests for acceleration.  Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
You may contact Keira Nakada at (202) 551-3659 or Kevin Vaughn at (202) 551-3494 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Jeffrey Gabor at (202) 551-2544 or Mary Beth Breslin at (202) 551-3625 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc: Adam Davey, Esq.

CORRESP
1
filename1.htm

CORRESP

 John T. Rudy | 617 348 3050 |
jrudy@mintz.com

 One Financial Center

Boston, MA 02111

 617-542-6000

617-542-2241 fax

www.mintz.com

CERTAIN PORTIONS OF THIS LETTER AS FILED VIA EDGAR HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION. CONFIDENTIAL
TREATMENT HAS BEEN REQUESTED FOR THE OMITTED PORTIONS, WHICH HAVE BEEN REPLACED WITH THE PLACEHOLDER “[***]”.

September 6, 2017

 VIA EDGAR

 Securities and Exchange
Commission

 Division of Corporation Finance

 100 F Street,
N.E.

 Washington, D.C. 20549

Attention:

Keira Nakada

Kenneth Vaughn

Jeffrey Gabor

Mary Beth Breslin

Re:
NuCana plc (formerly NuCana BioMed Limited)

Registration Statement on Form F-1 (File No. 333-220321)

Ladies and Gentlemen:

 On behalf of NuCana plc
(the “Company”), set forth below is additional information to supplement the Company’s prior response to comment 6 contained in the letter dated July 24, 2017 from the staff (the “Staff”) of the Securities
and Exchange Commission (the “Commission”) relating to the Draft Registration Statement on Form F-1, confidentially submitted by the Company to the Commission on June 26, 2017. Such Draft
Registration Statement has been updated by the Company as reflected in the amended Draft Registration Statement submitted on August 4, 2017 and the registration statement referenced above (File
No. 333-220321), which was publicly filed by the Company on September 1, 2017 (the “Registration Statement”). The supplemental response set forth below is based on information
provided to Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. by representatives of the Company.

 Confidential Treatment Request

Due to the commercially sensitive nature of information contained herein, the Company hereby requests, pursuant to 17 C.F.R. § 200.83, that certain
portions of this letter be maintained in confidence, not be made part of any public record and not be disclosed to any person as they contain confidential information. A redacted letter has been filed on EDGAR, omitting the confidential information
contained in the letter. The Company has separately provided to the Staff a copy of this letter, marked to show the portions redacted from the version filed via EDGAR and for which the Company is requesting confidential treatment. In accordance with
17 C.F.R. § 200.83(d)(1), if any person (including any governmental employee who is not an employee of the Commission) should request access to or an opportunity to inspect this letter, we request that we be immediately notified of any such
request, be furnished with a copy of all written materials pertaining to such request (including, but not limited to, the request itself) and be given at least ten business days advance notice of any intended release so that the Company may, if
deemed necessary or appropriate, pursue any remedies available to it. In such an event, we request that you telephone the undersigned rather than rely upon the U.S. mail for such notice. The address and telephone number for John T. Rudy, the
responsible representative, is c/o Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., One Financial Center, Boston, MA 02111, telephone number (617) 542-6000.

 Mintz, Levin,
Cohn, Ferris, Glovsky and Popeo, P.C.

 BOSTON | WASHINGTON | NEW YORK |
STAMFORD | LOS ANGELES | PALO ALTO | SAN DIEGO | LONDON

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

September 6, 2017

  Page
 2

 Staff Comment and Company Response

Critical Accounting Policies, Judgements and Estimates

Valuation of Ordinary Shares, p. 81

 Comment 6:
We may have additional comments on your accounting for equity issuances including stock based compensation and convertible instruments. Once you have an estimated offering price, please provide us an analysis explaining the reasons for the
differences between the recent valuations of your common stock leading up to the IPO and the estimated offering price.

 Response:

During 2016, the Company issued options for its ordinary shares on June 30, August 22, October 28 and December 12. During the six months ended
June 30, 2017, the Company issued options for its ordinary shares on May 16. Consistent with the Company’s historical practice, the fair value of the ordinary shares underlying each of these option grants was determined on each grant date
and, in the absence of a public trading market for the Company’s ordinary shares or American Depositary Shares (“ADSs”), various objective and subjective factors were considered to determine fair value, as described in detail
in the Registration Statement, including:

•

the lack of an active public market for the Company’s ordinary shares or ADSs, as well as the Company’s series A and series B convertible participating shares;

•

the prices of the Company’s series A and series B convertible participating shares sold to outside investors in arm’s length transactions, and the rights, preferences and privileges of the series A and series
B convertible participating shares relative to its ordinary shares;

•

the data generated from the Company’s research and development programs and financial condition;

•

the material risks related to the Company’s business and industry;

•

the Company’s business strategy;

•

the market performance of publicly traded companies in the life sciences and biotechnology sectors; and

•

the likelihood of achieving a liquidity event for the holders of the Company’s ordinary shares, such as an initial public offering (“IPO”), given prevailing market conditions.

 2

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

September 6, 2017

  Page
 3

 In addition, as part of its assessment of the fair value of the Company’s ordinary shares for purposes
of making stock option grants, the Company directed an independent valuation firm to complete retrospective valuations for June 30, 2016, August 22, 2016, October 28, 2016 and December 1, 2016 and a contemporaneous
valuation for May 16, 2017 using methodologies, approaches and assumptions consistent with the guidelines outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held-Company Equity Securities
Issued as Compensation (the “Practice Aid”).

 The following table summarizes by grant date the number of ordinary shares subject to
options granted between January 1, 2016 and June 30, 2017, the per share exercise prices, and the estimated per share fair values of the ordinary shares for financial reporting purposes. Except for the numbers set forth in the “Pre-Split” column of the table, all share numbers, as well as all option exercise prices and estimated fair values of ordinary shares referred to in this letter, have been adjusted to reflect an estimated
1(one) for [***] ([***]) reverse stock split of the Company’s capital stock (the “Stock Split”), which the Company plans to reflect in a subsequent pre-effective amendment
to the Registration Statement.

 3

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

September 6, 2017

  Page
 4

Pre-Split

Post-Split

 Date of Grant

Number of
Options
Granted

Per Share
Exercise
Price

Per Share Value
of Ordinary
Shares for
Financial
Reporting
Purposes

Number of
Options
Granted

Per Share
Exercise
Price

Per Share Value of
Ordinary Shares
for Financial
Reporting
Purposes

 6/30/2016

1,082,760

£
1.00

£
1.74

270,690

£
4.00

£
6.96

 8/22/2016

50,000

£
0.70

£
2.15

12,500

£
2.80

£
8.60

 8/22/2016

150,000

£
0.75

£
2.15

37,500

£
3.00

£
8.60

 8/22/2016

100,000

£
0.85

£
2.15

25,000

£
3.40

£
8.60

 8/22/2016

45,000

£
0.90

£
2.15

11,250

£
3.60

£
8.60

 8/22/2016

20,000

£
0.90

£
2.15

5,000

£
3.60

£
8.60

 8/22/2016

150,000

£
0.90

£
2.15

37,500

£
3.60

£
8.60

 10/28/2016

50,000

£
0.85

£
2.19

12,500

£
3.40

£
8.76

 10/28/2016

200,000

£
1.00

£
2.19

50,000

£
4.00

£
8.76

 12/12/2016

183,000

£
1.00

£
2.30

45,750

£
4.00

£
9.20

 5/16/2017

93,000

£
1.00

£
2.77

23,250

£
4.00

£
11.08

 A discussion of each valuation and related award is as follows:

Valuations

 The retrospective and contemporaneous
valuation appraisals used the market-based approach to determine an equity value. The Company utilized the guideline public company (“GPC”) method under the market-based approach to determine the estimated fair value of its
ordinary shares because it determined that this approach was the most appropriate for a clinical-stage biopharmaceutical company at this point in its development. In application of the GPC method under the market-based approach, the Company
considered the pricing of initial public offerings completed by clinical-stage oncology companies between April 2015 and May 2017. The Company calculated the median equity values for nine companies at the time of their IPOs, not including the IPO
proceeds. To convert the prospective IPO value to present value, the Company applied a discount rate which was derived from studies of rates of return required by venture investors in IPO-stage companies. In
addition to these GPCs, the Company considered the median enterprise value indicated by a group of eight trading GPCs whose trading prices provided contemporaneous indications of value as of each appraisal date. The Company’s equity

 4

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

September 6, 2017

  Page
 5

value was calculated as a weighted average of values indicated by the two groups of GPCs. To account for lack of access to an active public market, the Company applied a discount for lack of
marketability (“DLOM”) to the equity value. The DLOM was estimated using an Asian put model. Inputs to the Asian put model included time to liquidity and volatility. A Black-Scholes calculation was used to allocate the non-marketable equity value among issued shares and options. Inputs to the Black-Scholes calculation included option life and volatility. The Black-Scholes calculation relied on the expected life and volatility
assumptions derived from the DLOM analysis.

 A discussion of the discount rate, life and volatility assumptions associated with each grant and related
award subject to a retrospective or contemporaneous valuation follows below.

 June 30, 2016 Retrospective
Valuation. A discount rate of 25.0% was used to convert prospective IPO value to present value. In making the life and volatility assumptions, the Company assumed an IPO date of September 30, 2017 and a non-IPO liquidity date of June 30, 2019. The Company estimated it would be approximately 1.25 years until the Company’s IPO with a 40% probability of an IPO occurring. The Company estimated it would be
approximately 3.00 years until a non-IPO liquidity event with a 60% probability of such event occurring. The Company estimated a probability-weighted years to liquidity of 2.30. The corresponding volatility
applied was 77%. Based on these assumptions, the DLOM was estimated as 28%. The resulting fair value of the Company’s ordinary shares was £6.96 per share.

August 22, 2016 Retrospective Valuation. A discount rate of 25.0% was used to convert prospective IPO
value to present value. In making the life and volatility assumptions, the Company assumed an IPO date of September 30, 2017 and a non-IPO liquidity date of June 30, 2019. The Company estimated it
would be approximately 1.11 years until the Company’s IPO with a 50% probability of an IPO occurring. The Company estimated it would be approximately 2.85 years until a non-IPO liquidity event with a 50%
probability of such event occurring. The Company estimated a probability-weighted years to liquidity of 1.98. The corresponding volatility applied was 71%. Based on these assumptions, the DLOM was estimated as 23%. The resulting fair value of the
Company’s ordinary shares was £8.60 per share.

 October 28, 2016 Retrospective Valuation.
A discount rate of 25.0% was used to convert prospective IPO value to present value. In making the life and volatility assumptions, the Company assumed an IPO date of September 30, 2017 and a non-IPO
liquidity date of June 30, 2019. The Company estimated it would be approximately 0.92 years until the Company’s IPO with a 60% probability of an IPO occurring. The Company estimated it would be approximately 2.67 years until a non-IPO liquidity event with a 40% probability of such event occurring. The Company estimated a probability-weighted years to liquidity of 1.62. The corresponding volatility applied was 70%. Based on these
assumptions, the DLOM was estimated as 21%. The resulting fair value of the Company’s ordinary shares was £8.76 per share.

 5

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

September 6, 2017

  Page
 6

 December 1, 2016 Retrospective Valuation. A discount rate of
25.0% was used to convert prospective IPO value to present value. In making the life and volatility assumptions, the Company assumed an IPO date of September 30, 2017 and a non-IPO liquidity date of
June 30, 2019. The Company estimated it would be approximately 0.83 years until the Company’s IPO with a 70% probability of an IPO occurring. The Company estimated it would be approximately 2.67 years until a
non-IPO liquidity event with a 30% probability of such event occurring. The Company estimated a probability-weighted years to liquidity of 1.35. The corresponding volatility applied was 69%. Based on these
assumptions, the DLOM was estimated as 19%. The resulting fair value of the Company’s ordinary shares was £9.20 per share.

May 16, 2017 Contemporaneous Valuation. A discount rate of 25.0% was used to convert prospective IPO value to
present value. In making the life and volatility assumptions, the Company assumed an IPO date of September 30, 2017 and a non-IPO liquidity date of December 31, 2019. The Company estimated it would
be approximately 0.38 years until the Company’s IPO with an 80% probability of an IPO occurring. The Company estimated it would be approximately 2.63 years until a non-IPO liquidity event with a 20%
probability of such event occurring. The Company estimated a probability-weighted years to liquidity of 0.83. The corresponding volatility applied was 56%. Based on these assumptions, the DLOM was estimated as 12%. The resulting fair value of the
Company’s ordinary shares was £11.08 per share.

 The Company advises the Staff that it may grant additional options to certain employees in
September 2017 and prior to the IPO. To the extent that such options are granted, the Company also advises the Staff that once the bona fide initial offering price range has been determined, the Company anticipates retrospectively
reassessing, solely for financial accounting purposes, the ordinary share fair value related to such option grants.

 Preliminary IPO Price Range

 The Company supplementally advises the Staff that, while not yet reflected in the Registration Statement, on September 5, 2017, representatives
of the lead underwriters (the “Underwriters”) of its proposed IPO advised the Company that, based on then-current market conditions, they currently anticipated recommending to the Company a preliminary estimated initial public offering
price range of $[***] to $[***] per share (the “Preliminary IPO Price Range”) with a midpoint of $[***], if the Company were to commence marketing of the transaction on such date. Solely for purposes of
comparing this Preliminary IPO Price Range, which is expressed in U.S. dollars, with the valuations of the Company’s ordinary shares discussed above, which are expressed in pounds sterling, the Preliminary IPO Price Range as converted to pounds
sterling at the noon buying rate of the Federal Reserve Bank of New York as of June 30, 2017 (£1.2995 to $1.00) is £[***] to £[***] and the midpoint of that range is £[***].

The Preliminary IPO Price Range and the related Stock Split are based on existing conditions in the public capital markets for biotechnology companies, the
Company’s financial position and p

August 16, 2017
Hugh Griffith
Chief Executive Officer
NuCana BioMed Ltd
251 Little Falls Drive
Wilmington, DE 19808
NuCana BioMed Ltd
Amendment No. 1 to
Draft Registration Statement on Form F-1
Submitted August 4, 2017
CIK No. 0001709626Re:
Dear Mr. Griffith:
We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we may
better understand your disclosure.
Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments. Unless we note otherwise, our references to prior comments are to comments in our
July 24, 2017 letter.
DRS/A submitted 08/04/2017
Overview, page 1
1. We note your response to prior comment 2.  However, the current Summary disclosure
creates the impression that the FDA is likely to approve your candidate based on these
early trials even though the results "may not meet the level of statistical significance
required by the FDA or comparable regulatory authorities for marketing approval."

Hugh Griffith
NuCana BioMed Ltd
August 16, 2017
Page 2

Therefore, while we will not object if you discuss the control rates in the business section
with proper context, the Summary discussion is inappropriate. Please revise accordingly.
Business, page 84
2. We note your response to prior comment 10 and the amended disclosure that "in vitro
cytotoxic activity of NUC-7738 had more than 50 times greater anti-cancer activity than
cordycepin."  Please put this selected information into its full and proper context by
providing the specific details and parameters of the study from which this data was
drawn, including clinical endpoints, duration of treatment, comparison against placebo or
standard treatment, metrics utilized, statistical significance, etc.  Without this contextual
information, it may be difficult for the reader to draw an accurate and balanced
assessment of these favorable results.  If you cannot provide this information, please
delete the reference.
Notes to the Consolidated Financial Statements
2.  Significant Accounting Policies
Intangible Assets, page F-10
3. Please address the following regarding your response to prior comment 15:
    •  Tell us how you considered the impact of the relevant inherent uncertainties
including regulatory approval, commercialization, pricing, and competition as they affect
your ability to reliably determine a pattern of future economic consumption, such that a
pattern other than straight-line is appropriate pursuant to paragraph 97 of IAS 38.
    •  You state in your response to comment 15 that reverse sum of the years digits
reflects the increasing consumption of the economic benefit of the patent as the product
candidate approaches expiry.  However, you appear to have only considered the
commercial value of potential product revenue from the products the patents support,
which is contingent upon a significant number of factors culminating in regulatory
approval and significant market usage at favorable pricing.  Tell how you considered the
rebuttable presumption in paragraph 98A of IAS 38 that an amortization method that is
based on the revenue generated by an activity that includes the use of an intangible asset
is inappropriate.  As part of your consideration, specifically address how you considered
the early development stage of your product candidates, including the uncertainty of
regulatory approval which would be required for any future product revenue.
    •  To the extent you are able to overcome the rebuttable presumption noted above, tell
us how your amortization method reflects a similar inherent economic value to the patents
during the development period, such as allowing for the research and development of
candidates subject to the patent and/or keeping other entities from commercializing
products with similar underlying technologies.  Clearly explain how you weighted this
current economic value against the probabilities of future commercialization in
determining your amortization methodology.

Hugh Griffith
NuCana BioMed Ltd
August 16, 2017
Page 3
You may contact Keira Nakada at (202) 551-3659 or Kevin Vaughn at (202) 551-3494
if you have questions regarding comments on the financial statements and related matters.
Please contact Jeffrey Gabor at (202) 551-2544 or Mary Beth Breslin at (202) 551-3625 with any
other questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc: Adam Davey

July 24, 2017
Hugh Griffith
Chief Executive Officer
NuCana BioMed Ltd
251 Little Falls Drive
Wilmington, DE 19808
NuCana BioMed Ltd
Draft Registration Statement on Form F-1
Submitted June 26, 2017
CIK No. 0001709626Re:
Dear Mr. Griffith:
We have reviewed your registration statement and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.
Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comments apply to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
After reviewing any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Draft Registration Statement submitted 06/26/2017
Overview, page 1
1. Please define the terms "phosphoramidate," "metabolite," "nucleoside analogs" and
"nucleotide analog" where they are first used in this section.
2. We note your statements that Acelarin has been found in Phase 1 and Phase 1b trials to
have achieved a 78%, 94%, and 96% disease control rates for various indications.  We
also note your risk factor disclosure on page 18 that your "Phase1 and Phase 1b trials
have not been powered to show results with statistical significance."  Accordingly, as
these early-stage clinical trials may not be indicative of results obtained in later-stage
trials and were not designed to show results with statistical significance, please remove
the disclosure of the disease control rates from the Summary.

Hugh Griffith
NuCana BioMed Ltd
July 24, 2017
Page 2
3. Please revise your pipeline tables on pages 4 and 87 to reflect the actual status of your
pipeline candidates as of the latest practicable date.  The table suggests that you have
completed the Phase 1 trial of Acelarin in combination with carboplatin for the indication
of platinum-sensitive ovarian cancer and your current trial is in Phase 2; however, your
disclosure on page 3 indicates the Phase 1b trial is still ongoing.
Use of Proceeds, page 65
4. Please expand your disclosure regarding the proceeds to be used for your product
candidates to describe how far in the development process you estimate the allocated
proceeds from this offering will enable you to reach.
Management’s Discussion and Analysis of Financial Condition and Results of Operations
Results of Operations
Comparison of Years Ended December 31, 2015 and 2016
Research and Development Expenses, page 76
5. For each of your research and development programs, please separately disclose the costs
incurred during each period presented.
Critical Accounting Policies, Judgments and Estimates
Valuation of Ordinary Shares, page 81
6. We may have additional comments on your accounting for equity issuances including
stock based compensation and convertible instruments. Once you have an estimated
offering price, please provide us an analysis explaining the reasons for the differences
between the recent valuations of your common stock leading up to the IPO and the
estimated offering price.
Business, page 84
7. Please revise to describe clearly and consistently the regulatory status of your product
candidates and product development efforts to date and provide the following
information: regulatory applications submitted, if any, to commence clinical trial(s); the
current status of such applications and any significant dialogue with the FDA and/or
comparable regulatory agencies; and when and where the trials were conducted, who
conducted them, their scope and design, their endpoints, and whether these endpoints
were met.
8. Please revise to clarify scientific terms where used in the prospectus, such as
"dipyridamole" on page 100 and "pharmacokinetic" and "pharmacodynamic" on page
103.
9. We note your disclosure on page 103 and similar disclosure elsewhere that NUC-3373
should have an improved safety profile and improved efficacy as compared to 5-FU.
Because approval of the U.S. Food and Drug Administration ("FDA") and other

Hugh Griffith
NuCana BioMed Ltd
July 24, 2017
Page 3
comparable regulatory agencies is dependent on such agencies making a determination
(according to criteria specified in law and agency regulations) that a drug or biologic is
safe and effective, it is premature for you to describe or suggest that your product
candidates are safe or effective.  Accordingly, please revise these statements.
10. We note your statement on page 107 that "[i]n preclinical experiments, NUC-7738 was
over 50 times more potent in killing tumor cells than cordycepin."  Please put this
selected information into its full and proper context by providing the specific details and
parameters for which this data was drawn.
Intellectual Property, page 109
11. Please expand your disclosure to identify in which foreign jurisdictions you have issued
and pending patent applications.
12. Please expand your disclosure regarding the patent in the U.S. relating to the product
candidate Acelarin that "is currently under reissue" to explain the significance of the
reissue proceeding. Add any risk factor disclosure, if appropriate.
Consolidated Statements of Operations, page F-3
13. Please confirm that you have disclosed all material expenditures by nature as required
under paragraph 104 of IAS 1, or revise your disclosure to quantify these expenditures.
Notes to the Consolidated Financial Statements
2.  Significant Accounting Policies
Intangible Assets, page F-10
14. Please disclose your recognition policy for intangible assets, including legal costs relating
to obtaining, maintaining, and defending the patents.
15. Tell us how you determined that a decelerated amortization method such as reverse sum
of the years digits appropriately reflects the pattern in which your patent's future
economic benefits are expected to be consumed.  Refer to paragraphs 97-98C of IAS 38.
Tell us how you concluded you were able to reliably determine the pattern in which you
expect consume the future economic benefits for purposes of this guidance.  Tell us what
you determined to be the predominant limiting factor inherent in your patent intangibles.
Exhibits
16. Please tell us what consideration you have given to the filing of the service agreements
with your two executive officers and one of your non-executive directors and the
engagement agreement with one of your non-executive directors.  Please refer to Item
601(b)(10) of Regulation S-K.

Hugh Griffith
NuCana BioMed Ltd
July 24, 2017
Page 4
General
17. Please supplementally provide us with copies of all written communications, as defined in
Rule 405 under the Securities Act, that you, or anyone authorized to do so on your behalf,
present to potential investors in reliance on Section 5(d) of the Securities Act, whether or
not they retain copies of the communications.
18. Please provide us proofs of all graphics, visual, or photographic information you will
provide in the printed prospectus prior to its use, for example in a preliminary
prospectus.  Please note that we may have comments regarding this material.
We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
Refer to Rules 460 and 461 regarding requests for acceleration.  Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
You may contact Keira Nakada at (202) 551-3659 or Kevin Vaughn at (202) 551-3494 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Jeffrey Gabor at (202) 551-2544 or Mary Beth Breslin at (202) 551-3625 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc: Adam Davey