SecProbe.io

Mail Stop 4720

June 23, 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 May 23, 2016 response to our comment letter  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 these comments  within ten busine ss da ys by providing the requested
information or advis e 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  comme nts, we may have additional comments.
Unless we note otherwise, our references to prior comments are to comments in our May 2, 2016
letter .

Form 10 -K for the Year Ended December 31, 2015
Notes to Consolidated Financial Statements
3. Collaboration Agreeme nts
a. Sanofi
Immuno -Oncology, page F -16

1. Please refer to your response to our prior comment 3. Address each of the following in
order to further support a conclusion that the IO Collaboration and the amended Antibody
Collaboration are not in substance one  new arrangement :
 You indicate that:

Dr. Leonard S. Schleifer
Regeneron  Pharmaceuticals, Inc.
June 23, 2016
Page 2

 o the reductions in funding pursuant to the amended Antibody Discovery
Agreement from $160 million in each of 2015, 2016, and 2017 to $145 million,
$130 million, and $130 million, respectively, were not considered to be a
significant modification relative to Sanofi's overall funding obligations under the
Antibody Discovery Agreement ;
o the $75 million of aggregate funding from the Antibody Collaboration used to
reimburse the Company for a portion of its IO Discovery program  costs is not
material to the total anticipated funding under the IO Collaboration ; and
o although  IO product candidates and products will no longer be within the scope of
the Antibody Collaboration, the broad deliverables under the agreements
governing the Antibody Collaboration have not changed - i.e., the Company will
still be identifying and developing targets, providing research and development
and manufacturing services, etc., as originally required.
Explain to us why each of the above bullets is a fact or in concluding that the IO
Collaboration and the amended Antibody Collaboration should not be accounted for
together.
 You also indicate as a factor for not concluding that the IO Collaboration and the
amended Antibody Collaboration should not be account ed for together that there were
no discounts provided to Sanofi in the new IO Collaboration agreements. Since the IO
Collaboration was negotiated when you already had a significant contract with Sanofi
(i.e. the Antibody Collaboration) and at the same time  as the amended Antibody
Collaboration, provide us support for your assertion that no discounts were provided.
 Demonstrate to us that the different elements within the IO Collaboration are not
closely interrelated or interdependent in terms of design, tec hnology, or function to
elements in the amended Antibody Collaboration, and vice versa. Address as part of
your response to this bullet that IO product candidates have been moved from the
Antibody Collaboration to the IO Collaboration.
 Demonstrate to us  that one or more elements in the amended Antibody Collaboration
are not essential to the functionality of any element s in the IO Collaboration, and vice
versa.

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

2. Please refer to your response to our pr ior comment 5. Since you assert that your non -
GAAP net income and non -GAAP net income per share are measures of operating
performance, we do not believe it is appropriate to adjust GAAP taxes to show taxes paid
in cash and is inconsistent with question 102 .11 of the updated Compliance and
Disclosure Interpretations issued on May 17, 2016.  Please review this guidance when
preparing your next earnings release.

Dr. Leonard S. Schleifer
Regeneron  Pharmaceuticals, Inc.
June 23, 2016
Page 3

 You may contact Bonnie Baynes, Staff Accountant, at (202) 551 -4924 if you have
questions regarding the  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