SecProbe.io

Mail Stop 4720

May 2, 2016

VIA E -mail
Dr. Leonard S. Schleifer, M.D., Ph.D.
Presid ent and Chief Executive  Officer
Regeneron  Pharmaceuticals, Inc.
777 Old Saw Mill River Road ,
Tarrytown, New York  10591

Re: Regeneron  Pharmaceuticals, Inc.
 Form 10-K for Fis cal Year Ended December 31, 2015
Filed February 11, 2016
Form 8 -K dated February 9, 2016
Filed February 9, 2016
File No. 000-19034

Dear Dr. Schleifer :

We have reviewed your filing and have the following comments .  In some of our
comment s, we may ask you to provide us with information so we may better understand your
disclosure.

Please respond to these  comment s within ten  business days by providing the requ ested
information or advise  us as soon as possible  when you will respond .  If you do not believe  a
comment  applies to your facts and circumstances, please tell us why in your response.

After reviewing  your response to these  comment s, we may have additional co mments .

Form 10 -K for the Year Ended December 31, 2015

Patents, Trademarks, and Trade Secrets, page 22

1. We refer to the third paragraph under the heading which discloses that the patents for
your three commercially marketed products and ZALTRAP “generally” expire
between 2020 and 2029 and “may be subject” to extension.   Please confirm that you
will revise fu ture filings to discuss separately the patent coverage for each product
that is material to your business, including the patent expiration dates for any material
patents and the current status of efforts to extend those expiration dates.   Also, discuss
coverage by jurisdiction where material.   With reference to your disclosures in the
fourth paragraph under the heading, please also confirm that in future filings you will

Dr. Leonard S. Schleifer
Regeneron  Pharmaceuticals, Inc.
May 2 , 2016
Page 2

 revise your discussion of material licenses to discuss the term of those licenses.   To
the extent that the term of a material license is tied to patent expiration, please
confirm that you will identify the applicable expiration date in the future filing.

Notes to Consolidated Financial Statements

1. Business Overview and Summary of Significant Accounting Policies
Accounts Receivable – Trade, page F -10

2. Please tell us why your days  sales outstanding for the quarter ended March 31, 2014
of 199 days is substantially higher than for the quarter ended March 31, 2015 of 168
days. Further tell us why the days sales outstanding for each of these quarters is
substantially higher than for th e quarters for the rest of the respective fiscal year.  In
this regard, we computed days sales by dividing accounts receivable – trade, net as
end of a quarter by net product sales for the respective quarter and multiplying the
result by the number of days  in the quarter.

3. Collaboration Agreements
a. Sanofi
Immuno -Oncology, page F -16

3. Please provide us a full accounting analysis of the July 2015 IO Collaboration with
Sanofi and, as amended in connection with the IO Collaboration, the Antibody
Discover y Agreement and its License and Collaboration Agreement with Sanofi.
Include in your analysis:
 How you viewed the IO Collaboration and the amended agreements  (i.e.
separately or together) and the basis for your conclusion;
 Evaluation of the deliverables;
 Arrangement consideration, its determination and allocation;
 Revenue and expense recognition; and
 Authoritative literature supporting your analys is.

11. Debt
a. Convertible Debt
Warrant Transactions, page F -32

4. Please tell us why the amendment entere d into in November 2015 was not accounted
for similar to the amendment entered into in November 2014 whereby you accounted
for warrants as a liability effective with the amendment and subsequently measured
them at fair value with changes in fair value reco gnized in earnings.

Dr. Leonard S. Schleifer
Regeneron  Pharmaceuticals, Inc.
May 2 , 2016
Page 3

 Form 8 -K filed February 9, 2016
Exhibit 99.1
Table 3

5. Please refer to your non -GAAP net income and related per share amounts. Explain to
us precisely what the non -cash income tax adjustment represents and the components
included therein. Also explain to us what non -GAAP income taxes represent after the
non-cash income tax adjustment is deducted from GAAP income tax expense. In this
regard, it appears that not only do you exclude certain elements of income tax
expense in arriving a t non -GAAP net income, but it also appear that you fail to
recognize additional tax for the increase in pre -tax non -GAAP income. As such, it
does not appear that your non -GAAP net income reflects the full income tax
consequences of your pre -tax non -GAAP income. If that is the case, tell us what your
non-GAAP net income would have been for each of the last three fiscal years had you
included the  full income tax consequences of your pre -tax non -GAAP income.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing s to be certain that the filing s include the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules require.   Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.

 In respond ing to our comment s, please provide a written statement from the company
acknowledging that:
 the company is responsible for the adequacy and accuracy of the disclosure in the filing s;
 staff comment s or changes to disclosure in response to staff comment s do not foreclose
the Commission from taking any action with respect to the filing s; and
 the company may not assert staff comment s as a defense in any proceeding initiated by
the Commission or any person under the federal securities laws of the United States.

You may contact Bonnie Baynes, Staff Accountant, at (202) 551 -4924 if you have
questions regarding the processing of your response as well as any questions regarding
comments on the financial  statements and related matters .  Please  contact Dorman Yale, S taff
Attorney, at (202) 551 -8776 or Joseph McCann, Attorney Advisor, at (202) 551 -6262 with
question s on any of the  other  comments.   In this regard, do not hesitate to contact me at (202)
551-3679.
Sincerely,

  /s/ Jim B. Rosenberg

Jim B. Rosenberg
Senior Assistant Chief  Accountant
Office of Healthcare and Insurance