Exhibit 10.1

CONFIDENTIAL
December 31, 2017

Robert Terifay
[Address]

Re:
Retirement from Regeneron

Dear Bob:

This letter (this “Agreement”) sets forth the agreement reached concerning your
retirement from, and resulting conclusion of your employment with, Regeneron
Healthcare Solutions, Inc., including its current and former parents,
subsidiaries and affiliated entities, and their respective current and former
successors, assigns, representatives, agents, attorneys, shareholders, members,
officers, directors and employees, both individually and in their official
capacities (collectively “Regeneron”).
1.Your service to Regeneron as an active employee will conclude on January 5,
2018 and your position as Executive Vice President, Commercial will end on that
date. Thereafter, you will be placed on an unpaid personal leave of absence and
then transition into retirement as described further below in paragraph 2.
Regeneron will continue your salary, less applicable withholdings and
deductions, through January 5, 2018. In addition, you acknowledge and agree that
you are hereby tendering your resignation as an officer of Regeneron
Pharmaceuticals, Inc. and as a director and/or officer of any subsidiary of
Regeneron Pharmaceuticals, Inc. (if and as applicable) effective as of January
5, 2018.
2.In consideration for signing this Agreement and in exchange for the promises,
covenants and waivers set forth herein, Regeneron will, provided you have not
revoked the Agreement, place you on an unpaid personal leave of absence for
medical purposes and provide you with continued benefits through and including
July 31, 2018 as set forth in this paragraph 2. The period between January 5,
2018 and July 31, 2018 shall be referred to as the “Leave-of-Absence Period.”
Upon expiration of the Leave-of-Absence Period on July 31, 2018, such continued
benefits will end for all purposes. Your retirement will commence on August 1,
2018. During the Leave-of-Absence Period, (i) you shall not perform or provide
any work or services for Regeneron, in the office or outside of it, and you may
not discuss any Regeneron business with any Regeneron employees, consultants,
collaborators, contractors, or other third-parties, unless you receive advanced
authorization from Leonard Schleifer, President, Chief Executive Officer, Sally
Paull, Senior Vice President, Chief Human Resources Officer, or Joseph LaRosa,
Senior Vice President, General Counsel & Secretary; (ii) you will not have
access to Regeneron’s electronic communications systems; (iii) you will remain
subject to Regeneron’s policies and procedures, as set forth in its employee
handbook; (iv) you may not bind or attempt to bind Regeneron in connection with
any business

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matter; (v) you will not receive any salary payments; (vi) you will remain
eligible to participate in Regeneron’s health insurance plans, 401k, flexible
spending plan, and similar benefits, except that you will not continue to accrue
vacation days; (vii) you will be eligible to receive a performance bonus (or any
portion thereof) in connection with or in respect to the work you performed in
2017 to be paid in accordance with Regeneron’s policies and practices and at
management’s discretion; (viii) subject to the earlier expiration as provided in
the applicable Notice of Grant of Stock Options, the applicable Option
Agreement, and/or the applicable Equity Incentive Plan (as defined below), all
of the options granted to you under the Regeneron Pharmaceuticals, Inc. 2014
Long-Term Incentive Plan or the Regeneron Pharmaceuticals, Inc. Second Amended
and Restated 2000 Long-Term Incentive Plan (each as may be amended or restated
and in each case any successor thereto) (collectively, the “Equity Incentive
Plans” and, each individually, an “Equity Incentive Plan”) that remain
outstanding as of the date hereof shall, to the extent unvested, continue to
vest and, to the extent vested and exercisable, remain vested and exercisable
(for the avoidance of doubt, all vesting of the options granted to you under any
of the Equity Incentive Plans shall cease at the end of the Leave-of-Absence
Period on July 31, 2018); and (ix) subject to the provisions of paragraph 9
below, you must keep this Agreement, the Leave-of-Absence Period, and any
discussions pertaining to this arrangement, confidential.
3.    If you comply with the terms and conditions set forth in paragraph 2
above, and at or about the time of the end of the Leave-of-Absence Period, you
execute and do not revoke a second separation agreement, in substantially the
same form as this Agreement, Regeneron will provide you with continued health
benefits coverage under COBRA through January 31, 2020. The benefit under this
paragraph shall be provided only so long as you qualify and timely apply for
COBRA coverage. Notwithstanding the foregoing, in the event a COBRA benefit
violates the nondiscrimination rules under the Patient Protection and Affordable
Care Act (as amended by the Health Care and Education Reconciliation Act of 2010
and as amended from time to time) (the “Affordable Care Act”), Regeneron will
use its reasonable efforts to provide additional benefits equivalent to the
payments forfeited if and to the extent permitted under the Affordable Care Act.
4.    In consideration of the payment described above and for other good and
valuable consideration, you hereby release and forever discharge Regeneron from
all debts, obligations, promises, covenants, agreements, contracts,
endorsements, bonds, controversies, suits, actions, causes of action, judgments,
damages, expenses, claims or demands, in law or in equity, which you ever had,
now have, or which may arise in the future, regarding any matter arising on or
before the date of your execution of this Agreement, including but not limited
to all claims (whether known or unknown) regarding your employment at or
retirement from Regeneron, any contract (express or implied), any claim for
equitable relief or recovery of punitive, compensatory, or other damages or
monies, attorneys' fees, any tort, and all claims for alleged discrimination
based upon age, race, color, sex, sexual orientation, marital status, religion,
national origin, handicap, disability, genetic information or retaliation,
including any claim, asserted or unasserted, which could arise under Title VII
of the Civil Rights Act of 1964; the Equal Pay Act of 1963; the Age
Discrimination in Employment Act of 1967; the Older Workers Benefit Protection
Act of 1990; the Americans With Disabilities Act of 1990; the Civil Rights Act
of 1866, 42 U.S.C. § 1981; the Genetic Information

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Nondiscrimination Act of 2008; the Family and Medical Leave Act of 1993; 31
U.S.C. §§3729-3733; the Employee Retirement Income Security Act of 1974; the
Civil Rights Act of 1991; the Worker Adjustment and Retraining Notification
(“WARN”) Act of 1988; the New York State WARN Act; the New York State Human
Rights Law; the New York City Human Rights Law; the New York State Labor Law;
and any other federal, state or local laws, rules or regulations, whether equal
employment opportunity laws, rules or regulations or otherwise, or any right
under any Regeneron pension, welfare, or stock plans (including, without
limitation, the Equity Incentive Plans). This Agreement may not be cited as, and
does not constitute any admission by Regeneron of, any violation of any such law
or legal obligation.
5.    You represent, warrant and agree that you have not filed any lawsuits or
arbitrations against Regeneron, or filed or caused to be filed any claims,
charges or complaints against Regeneron in any administrative, judicial,
arbitral or other forum, including any charges or complaints against Regeneron
with any international, federal, state or local agency charged with the
enforcement of any law or any self regulatory organization, and you are not
aware of any factual or legal basis for any legitimate claim that Regeneron is
in violation of any whistleblower, corporate compliance, or other regulatory
obligation of Regeneron under international, federal, state or local law, rule
or Regeneron policy. You further represent, warrant and agree that if you were
ever aware of any such basis for a legitimate claim against Regeneron, you
informed Regeneron of same.
6.    Nothing in this Agreement, including, but not limited to, paragraphs 3, 4,
7, 8, 9, 10, 11, 13, or 15, shall prohibit or restrict you (or your attorney)
from filing a charge, testifying, assisting, or participating in any manner in
an investigation, hearing or proceeding; responding to any inquiry; or otherwise
communicating with, any administrative or regulatory agency or authority,
including, but not limited to, the Equal Employment Opportunity Commission
(EEOC) and the National Labor Relations Board (NLRB). To the extent permitted by
law, if any lawsuits, arbitrations, claims, charges or complaints are filed
against Regeneron in any administrative, judicial, arbitral or other forum,
including any charges or complaints against Regeneron with any international,
federal, state or local agency by a third party or otherwise, you expressly
waive any claim to any form of monetary or other damages, or any other form of
recovery or relief in connection with any such proceeding.
7.    You represent, warrant and acknowledge that Regeneron owes you no wages,
commissions, bonuses, sick pay, personal leave pay, severance pay, vacation pay
or other compensation or benefits or payments or form of remuneration of any
kind or nature, other than that specifically provided for in this Agreement. 
8.    You agree not to disclose, nor use for your benefit or the benefit of any
other person or entity, any information received in connection with Regeneron
which is confidential or proprietary and (i) which has not been disclosed
publicly by Regeneron, (ii) which is otherwise not a matter of public knowledge
or (iii) which is a matter of public knowledge but you know or have reason to
know that such information became a matter of public knowledge through an
unauthorized disclosure. Proprietary or confidential information shall include
information the unauthorized disclosure or use of which would reduce the value
of such information to Regeneron. Such information

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includes, without limitation, Regeneron’s client lists, its trade secrets, any
confidential information about (or provided by) any client or prospective or
former client of Regeneron, information concerning Regeneron’s business or
financial affairs, including its books and records, commitments, procedures,
plans and prospects, products developed by Regeneron, or current or prospective
transactions or business of Regeneron and any “inside information.” You agree
that such information provides Regeneron with a unique and valuable competitive
advantage. You hereby confirm that you have delivered to Regeneron and retained
no copies of any written materials, records and documents (including those that
are electronically stored) made by you or coming into your possession during the
course of your employment with Regeneron which contain or refer to any such
proprietary or confidential information. You further confirm that you have
delivered to Regeneron any and all property and equipment of Regeneron,
including laptop computers, smartphones, identification cards, and keys, etc.,
which may have been in your possession. Pursuant to the Defend Trade Secrets Act
of 2016, you are hereby informed and understand that an individual may not be
held criminally or civilly liable under any federal or state trade secret law
for the disclosure of a trade secret that: (a) is made (i) in confidence to a
federal, state, or local government official, either directly or indirectly, or
to an attorney; and (ii) solely for the purpose of reporting or investigating a
suspected violation of law; or (b) is made in a complaint or other document that
is filed under seal in a lawsuit or other proceeding. Further, an individual who
files a lawsuit for retaliation by an employer for reporting a suspected
violation of law may disclose the employer's trade secrets to the attorney and
use the trade secret information in the court proceeding if the individual: (a)
files any document containing the trade secret under seal; and (b) does not
disclose the trade secret, except pursuant to court order.
9.    You agree not to disclose the terms, contents or execution of this
Agreement, the claims that have been or could have been raised against
Regeneron, or the facts and circumstances underlying this Agreement, except in
the following circumstances:
a.    You may disclose the terms of this Agreement to your immediate family, so
long as such family member agrees to be bound by the confidential nature of this
Agreement;
b.    You may disclose the terms of this Agreement to (i) your tax advisors so
long as such tax advisors agree in writing to be bound by the confidential
nature of this Agreement (ii) taxing authorities if requested by such
authorities and so long as they are advised in writing of the confidential
nature of this Agreement or (iii) your legal counsel;
c.    If disclosure of the terms of this Agreement has been made publicly by
Regeneron (including, without limitation, in a filing made by Regeneron with the
U.S. Securities and Exchange Commission), but solely to the extent of such
public disclosure; and
d.    Pursuant to the order of a court or governmental agency of competent
jurisdiction, or for purposes of securing enforcement of the terms and
conditions of this Agreement should that ever be necessary.

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10.    You will not disparage Regeneron, or issue any communication, written or
otherwise, that reflects adversely on or encourages any adverse action against
Regeneron, except if testifying truthfully under oath pursuant to any lawful
court order or subpoena or otherwise responding to or providing disclosures
required by law. This includes any statement to or response to an inquiry by any
member of the press or media, whether written, verbal, electronic, or otherwise.
11.    Nothing in this Agreement shall prohibit or restrict you (or your
attorney) from responding to any inquiry, or otherwise communicating with, any
federal, state or local administrative or regulatory agency or authority about
this Agreement or its underlying facts and circumstances.
12.    Upon service on you, or anyone acting on your behalf, of any subpoena,
order, directive or other legal process requiring you to engage in conduct
encompassed within paragraphs 6, 8, 9 or 11 of this Agreement, you or your
attorney shall immediately notify Regeneron of such service and of the content
of any testimony or information to be provided pursuant to such subpoena, order,
directive or other legal process and within two (2) business days send to the
undersigned representative of Regeneron via overnight delivery (at Regeneron’s
expense) a copy of the documents that have been served upon you. Provided,
however, that if you are requested to respond to an inquiry or provide testimony
by or before any federal, state or local administrative or regulatory agency or
authority about this Agreement or its underlying facts and circumstances, you
(or your attorney) should fulfill your obligation to Regeneron, as set forth in
this paragraph, only after you have responded to the inquiry or provided the
testimony sought.
13.    Regeneron may deduct or withhold from any compensation or benefits any
applicable federal, state or local tax or employment withholdings or deductions
resulting from any payments or benefits provided under this Agreement as if you
were an employee. In addition, it is Regeneron’s intention that all payments or
benefits provided under this Agreement comply with Section 409A of the Internal
Revenue Code of 1986, as amended (the “Code”), including without limitation the
six month delay for payments of deferred compensation to “key employees” upon
separation from service pursuant to Section 409A(a)(2)(B)(i) of the Code (if
applicable), and this Agreement shall be interpreted, administered and operated
accordingly. If under this Agreement an amount is to be paid in installments,
each installment shall be treated as a separate payment for purposes of Treasury
Regulation Section 1.409A-2(b)(2)(iii). Notwithstanding anything to the contrary
herein, Regeneron does not guarantee the tax treatment of any payments or
benefits under this Agreement, including without limitation under the Code,
federal, state, local or foreign tax laws and regulations.
14.    You agree that you will reasonably assist and cooperate with Regeneron in
connection with the defense or prosecution of any claim that may be made against
or by Regeneron. Your cooperation shall include, but not be limited to, meeting
with Regeneron’s counsel, providing information as requested, attending meetings
with others as requested by Regeneron, testifying in any proceeding before any
arbitral, administrative, judicial, legislative, or other body or agency, and
providing interviews or depositions as may be requested. You further agree to
testify truthfully in any proceeding to the extent such claims, investigations
or proceedings relate to services performed or required to be performed by you,
pertinent knowledge possessed by you,

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or any act or omission by you. You further agree to perform all acts and execute
and deliver any documents that may be reasonably necessary to carry out the
provisions of this paragraph.
15.    This Agreement constitutes the entire agreement between Regeneron and
you, and supersedes and cancels all prior and contemporaneous written and oral
agreements between Regeneron and you, except that your Agreement Regarding
Certain Terms and Conditions of Your Employment, shall remain in full force and
effect. You affirm that, in entering into this Agreement, you are not relying
upon any oral or written promise or statement made by anyone at any time on
behalf of Regeneron.
16.    This Agreement is binding upon you and your successors, assigns, heirs,
executors, administrators and legal representatives.
17.    If any of the provisions, terms or clauses of this Agreement is declared
illegal, unenforceable or ineffective in a legal forum, those provisions, terms
and clauses shall be deemed severable, such that all other provisions, terms and
clauses of this Agreement shall remain valid and binding upon both parties.
18.    Without detracting in any respect from any other provision of this
Agreement:
a.    You, in consideration of the payment provided to you as described in
paragraph 2 of this Agreement, agree and acknowledge that this Agreement
constitutes a knowing and voluntary waiver of all rights or claims you have or
may have against Regeneron as set forth herein, including, but not limited to,
all rights or claims arising under the Age Discrimination in Employment Act of
1967, as amended (“ADEA”), including, but not limited to, all claims of age
discrimination in employment and all claims of retaliation in violation of the
ADEA; and you have no physical or mental impairment of any kind that has
interfered with your ability to read and understand the meaning of this
Agreement or its terms, and that you are not acting under the influence of any
medication or mind-altering chemical of any type in entering into this
Agreement.
b.    You understand that, by entering into this Agreement, you do not waive
rights or claims that may arise after the date of your execution of this
Agreement, including without limitation any rights or claims that you may have
to secure enforcement of the terms and conditions of this Agreement.
c.    You agree and acknowledge that the consideration provided to you under
this Agreement is in addition to anything of value to which you are already
entitled.
d.    Regeneron hereby advises you to consult with an attorney prior to
executing this Agreement.
e.    You acknowledge that you were informed that you had at least twenty-one
(21) days in which to review and consider this Agreement and to consult with an
attorney regarding the terms and effect of this Agreement.
f.    Nothing in this Agreement shall prevent you (or your attorneys) from (i)
commencing an action or proceeding to enforce this Agreement or (ii) exercising
your right under the Older Workers Benefit Protection Act of 1990 to

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challenge the validity of your waiver of ADEA claims set forth in paragraph 4 of
this Agreement.
19.    You may revoke this Agreement within seven (7) days from the date you
sign this Agreement, in which case this Agreement shall be null and void and of
no force or effect on either Regeneron or you. Any revocation must be in writing
and received by Regeneron before the end of the seventh day after this Agreement
is executed by you. Such revocation must be sent to the undersigned at
Regeneron.

The remainder of this page is left blank intentionally.

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20.    This Agreement may not be changed or altered, except by a writing signed
by Regeneron and you. This Agreement is entered into in the State of New York,
and the laws of the State of New York will apply to any dispute concerning it,
excluding the conflict-of-law principles thereof. Furthermore, any action
regarding this Agreement or its enforcement shall be subject to the exclusive
jurisdiction of the courts of New York County, New York. To the extent
permissible under applicable law, you hereby agree to waive your right to a jury
trial in connection with any claim you may have against Regeneron.

Date:    January 15, 2018     
            /s/ Robert Terifay
 
              Robert Terifay

On this 15th day of January 2018, before me personally came Robert Terifay, to
me known to be the individual described in the foregoing instrument, who
executed the foregoing instrument in my presence, and who duly acknowledged to
me that s/he executed the same.
 
            /s/ Lynne E. Baycora
 
              Notary Public

 
 
Regeneron Pharmaceuticals, Inc.

 
 
 
Date:    1/19/18             
By:
           /s/ Sally A. Paull
 
 
Name: Sally A. Paull
 
 
Title: Senior Vice President, Human Resources

You must sign and return this Agreement to Regeneron within twenty-one days of
your receipt of this Agreement or irrevocably lose the opportunity to receive
the consideration detailed herein. You received this Agreement on December 31,
2017.