EX-10.20



 Exhibit 10.20 

EXECUTIVE EMPLOYMENT AGREEMENT 

This EXECUTIVE EMPLOYMENT AGREEMENT (the “Agreement”) between Eloxx Pharmaceuticals, Inc. (the “Company”),
and Pedro Huertas (the “Executive”) is dated as of March 12, 2018 and shall become effective on March 12, 2018 (the “Effective Date”). 

W I T N E S S E T H: 
 WHEREAS,
the Company desires the Executive to provide employment services to the Company, and wishes to provide the Executive with certain compensation and benefits in return for such employment services; and 

WHEREAS, the Executive wishes to be employed by the Company and to provide employment services to the Company in return for certain
compensation and benefits; 
 NOW THEREFORE, in consideration of the foregoing, of the mutual promises contained herein and of other good
and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows: 
 1.
EMPLOYMENT TERM. The Company hereby offers to employ the Executive, and the Executive hereby accepts employment by the Company, upon the terms and conditions set forth in this Agreement, during the period commencing on the Effective
Date and ending on the date of the termination of the Executive’s employment in accordance with Section 7 below (the “Employment Term”). The Executive shall be employed at will, meaning that either the Company or the
Executive may terminate this Agreement and the Executive’s employment at any time, for any reason or no reason, with or without cause, subject to the terms of this Agreement. 

2. POSITION & DUTIES. 

(a) Except as provided in Section 2(b) below, the Executive shall serve as the Chief Medical Officer of the Company and its US subsidiary,
Eloxx Pharmaceuticals U.S. Sub, Inc. during the Employment Term. As Chief Medical Officer, the Executive shall have such duties, authorities and responsibilities as are commensurate with the position of Chief Medical Officer and such other duties
and responsibilities as the Company’s Chief Executive Officer shall designate that are consistent with the Executive’s position as Chief Medical Officer. 

(b) During the Employment Term, the Executive agrees to devote his full business time, attention and energies to the performance of all of the
lawful duties, responsibilities and authority that may be assigned to him hereunder. Nothing contained in this Agreement will preclude the Executive from (i) devoting time to personal and family investments, (ii) serving as a director of
any not-for-profit company, (iii) serving as a director for any for-profit company that is approved by the Board of
Directors (the “Board”) (such approval not to be unreasonably withheld) or (iv) from participating in charitable or industry associations, in each case, provided that such activities or services do not
(x) materially interfere with the Executive’s performance of duties hereunder or (y) violate the terms of the Confidentiality Agreement (as defined below). 

  
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 (c) During the Employment Term, the Executive’s principal place of employment shall be the
Company’s offices in Waltham, Massachusetts, subject to customary business travel consistent with the Executive’s duties and responsibilities. 

3. BASE SALARY. The Company agrees to pay the Executive a base salary (the “Base Salary”) at an annual rate of
US$346,500. The Base Salary will be payable bimonthly in accordance with the regular payroll practices of the Company. The Executive’s Base Salary shall be subject to review by the Company’s Chief Executive Officer at least annually and
may be increased, but not decreased, from time to time by the Company’s Chief Executive Officer. The base salary as determined herein from time to time shall constitute “Base Salary” for purposes of this Agreement. 

4. BONUSES. 
 (a)
ANNUAL BONUS. With respect to each full calendar year during the Employment Term, the Executive shall be eligible to earn an annual, performance-based bonus (an “Annual Bonus”) with a target bonus value equal to forty percent
(40%) of the Executive’s Base Salary (the “Target Bonus”) based upon the achievement of performance targets, which shall be established by the Board (or a committee thereof) in consultation with the Executive within the first
90 days of each calendar year during the Employment Term, with the actual amount of the Annual Bonus for a particular year determined by the Board (or a committee thereof) in its discretion. The Board (or a committee thereof) shall consider the
Executive’s performance in the entire 2018 calendar year without regard to the Effective Date when determining the Executive’s Annual Bonus for the 2018 calendar year. Subject to Section 8 below, in order to be eligible for an Annual
Bonus, the Executive must remain employed for the entire calendar year for which the performance targets will have been set. Any Annual Bonus earned by the Executive will be paid no later than March 15 of the calendar year immediately following
the calendar year in which the Annual Bonus is being measured. The Executive’s Target Bonus shall be subject to review by the Board (or a committee thereof) at least annually and may be increased, but not decreased, from time to time by the
Board. 
 5. EQUITY COMPENSATION. 

The Company will grant to the Executive as soon as practicable after the Company’s adoption of its 2018 Equity Incentive Plan (the
“Grant Date”) equity compensation awards under the 2018 Equity Incentive Plan (the “Plan”) consisting of a stock option of 104,725 shares and an RSU award of 104,725 shares, to vest over four years with one-fourth (1/4) of the grant vesting on the first anniversary of the Grant Date (the “Cliff Vesting Date”) and one-sixteenth (1/16) of the grant vesting on
each successive quarterly anniversary of the Cliff Vesting Date. The stock option award contemplated by this Section will have an exercise price equal to the closing price on the Grant Date. 

6. EMPLOYEE BENEFITS. 

(a) BENEFIT PLANS. The Executive shall be entitled to participate in all employee benefit plans that the Company generally makes
available to its senior executives (other than severance plans) from time to time, including any group health plans, dental plans, 

  
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life, disability and AD&D insurances, a 401(k) plan, tuition reimbursement, recreation allowance, parking or public transportation and various types of paid time off, subject to the terms and
conditions of such benefit plans. The Company shall adopt vision, health, dental and 401(k) plans no later than April 1, 2018. Until the Company does have such plans adopted, the Company will reimburse the Executive for 100% of the cost of
COBRA insurance coverage from Executive’s prior employer, as well as for costs of dental treatments otherwise covered by the Executive’s current dental plan. 

(b) VACATION. The Executive shall be entitled to twenty (20) days of paid vacation per year, in accordance with the Company’s
vacation policy; provided that the Executive shall be entitled to twenty-five (25) days of paid vacation per year after three (3) full calendar years of employment. Vacation may be taken at such times as the Executive elects
with due regard to the needs of the Company. 
 (c) BUSINESS EXPENSES. The Company will reimburse the Executive for all reasonable
business expenses incurred by the Executive in connection with the discharge of his duties for the Company, subject to the Company’s expense reimbursement policy in effect from time to time. 

(d) INDEMNIFICATION. The Company shall indemnify the Executive to the maximum extent that its officers, directors and employees are
entitled to indemnification pursuant to the Company’s Certificate of Incorporation and Bylaws for any acts or omissions by reason of being a director, officer or employee of the Company as of the Effective Date. At all times during the
Employment Term, the Company shall maintain in effect a director and officers liability insurance policy with the Executive as a covered officer and director. 

7. TERMINATION. The Executive’s employment and the Employment Term shall terminate on the first of the following to occur:

 (a) DISABILITY. Upon the 30th day following the Executive’s receipt of
notice of the Company’s intention to terminate the Executive’s employment due to Disability (as defined in this Section 7(a)); provided that, the Executive has not returned to full-time performance of his duties within
30 days after receipt of such notice. If the Company determines in good faith that the Executive’s Disability has occurred during the term of this Agreement, it will give the Executive written notice of its intention to terminate his
employment. For purposes of this Agreement, “Disability” shall mean the Executive’s inability to substantially perform the essential duties of his job with or without reasonable accommodation on a full-time basis for
180 calendar days during any consecutive twelve-month period or for 90 consecutive days as a result of incapacity due to mental or physical illness. 

(b) DEATH. Automatically on the date of death of the Executive. 

(c) CAUSE. Immediately upon written notice by the Company to the Executive of a termination for Cause. “Cause” shall
mean (i) the Executive’s commission of an act of fraud, embezzlement or theft against the Company or its subsidiaries; (ii) the Executive’s conviction of, or a plea of no contest to, a felony; (iii) willful nonperformance by
the Executive (other than by reason of illness) of his material duties as an employee of the Company, which, to 

  
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the extent it is curable by the Executive, is not cured within thirty (30) days after written notice thereof is given to the Executive by the Company; (iv) the Executive’s material
breach of this Agreement or any other material agreement between the Executive and the Company or any of its subsidiaries, including the Confidentiality Agreement, which, to the extent it is curable by the Executive, is not cured within thirty
(30) days after written notice thereof is given to the Executive by the Company; or (v) the Executive’s gross negligence, willful misconduct or any other act of willful disregard for the Company’s or any of its subsidiaries’
best interests, which, to the extent it is curable by the Executive, is not cured within thirty (30) days after written notice thereof is given to the Executive by the Company. 

(d) WITHOUT CAUSE. Upon written notice by the Company to the Executive no earlier than eighteen (18) months after the Effective
Date of an involuntary termination without Cause and other than due to death or Disability. 
 (e) GOOD REASON. “Good
Reason” for the Executive to terminate the Executive’s employment hereunder shall mean the occurrence of any of the following conditions during the Employment Term without the Executive’s express written consent; provided
that any resignation by the Executive due to any of the following conditions shall only be deemed for Good Reason if: (i) the Executive gives the Company written notice of the intent to terminate for Good Reason within sixty
(60) days following the first occurrence of the condition(s) that the Executive believes constitutes Good Reason, which notice shall describe such condition(s); (ii) the Company fails to remedy, if remediable, such condition(s) within thirty
(30) days following receipt of the written notice (the “Cure Period”) of such condition(s) from the Executive; and (iii) the Executive actually resigns his employment within the first thirty (30) days after expiration
of the Cure Period: 
 (1) any material reduction by the Company of the Executive’s Base Salary or Target Bonus as initially set forth
herein or as the same may be increased from time to time; 
 (2) any material diminution in the Executive’s duties, title,
responsibilities or authority; 
 (3) a requirement that the Executive report to a corporate officer or employee other than the
Company’s Chief Executive Officer, other than any such requirement following a Significant Event (as defined in the Company’s 2013 Share Ownership and Option Plan); 

(4) any material breach of this Agreement, including a breach of the Company’s obligations under Section 4, 6
or 11(b); or 
 (5) a requirement that the Executive relocate to a principal place of employment more than seventy-five
(75) miles from Waltham, Massachusetts. 
 (f) WITHOUT GOOD REASON. The Executive shall provide two (2) weeks’ prior
written notice (the “Transition Period”) to the Company of the Executive’s intended termination of employment without Good Reason (“Voluntary Termination”). During the Transition Period, the Executive shall
assist and advise the Company in any transition of 

  
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business, customers, prospects, projects and strategic planning, and the Company shall pay the pro rata portion of the Executive’s Base Salary and benefits through the end of the Transition
Period. The Company may, in its sole discretion, upon written notice to the Executive, make such termination of employment effective earlier than the expiration of the Transition Period (“Early Termination Right”), but it shall pay
the pro rata portion of the Executive’s Base Salary and benefits through the earlier of: the end of the Transition Period, or the date that the Executive accepts employment or a consulting engagement from a third party. 

8. CONSEQUENCES OF TERMINATION. Any termination payments made and benefits provided under this Agreement to the Executive shall
be in lieu of any termination or severance payments or benefits for which the Executive may be eligible under any of the plans, policies or programs of the Company or its affiliates as may be in effect from time to time. Subject to satisfaction of
each of the conditions set forth in Section 9, the following amounts and benefits shall be due to the Executive: 
 (a)
DISABILITY. Upon employment termination due to Disability, the Company shall pay or provide the Executive: (i) any unpaid Base Salary through the date of termination and any accrued vacation; (ii) reimbursement for any unreimbursed
expenses owed to Executive; and (iii) all other payments and benefits to which the Executive is entitled under the terms of any applicable compensation arrangement or benefit, equity or other plan or program, including but not limited to any
applicable insurance benefits, payable on the next regularly scheduled Company payroll date following the date of termination or earlier if required by applicable law (collectively, “Accrued Amounts”). In addition, upon the
Executive’s termination due to Disability, the Company shall pay the amounts described in Sections 8(d)(3) and 8(d)(4) to the Executive. 

(b) DEATH. In the event the Employment Term ends on account of the Executive’s death, the Executive’s estate (or to the
extent a beneficiary has been designated in accordance with a program, the beneficiary under such program) shall be entitled to any Accrued Amounts, including but not limited to proceeds from any Company sponsored life insurance programs. In
addition, upon the Executive’s death, the Company shall pay the amounts described in Sections 8(d)(3) and 8(d)(4) to the Executive’s estate. 

(c) TERMINATION FOR CAUSE OR WITHOUT GOOD REASON. If the Executive’s employment should be terminated (i) by the Company for
Cause, or (ii) by the Executive without Good Reason, the Company shall pay to the Executive any Accrued Amounts only, and shall not be obligated to make any additional payments to the Executive. 

(d) TERMINATION WITHOUT CAUSE OR FOR GOOD REASON. If the Executive’s employment by the Company is terminated by the Company other
than for Cause (and not due to Disability or death) or by the Executive for Good Reason, other than in circumstances described in Section 8(e), then the Company shall pay or provide the Executive with the Accrued Amounts and subject to
compliance with Section 10: 
 (1) continued payment of the Executive’s Base Salary as in effect immediately preceding the last
day of the Employment Term for a period of twelve (12) months following the termination date (the “Salary Severance Period”) in accordance with the 

  
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Company’s ordinary payroll practices (for purposes of calculating the Executive’s severance benefits, the Executive’s Base Salary shall be calculated based on the rate in effect
prior to any material reduction in Base Salary that would give the Executive the right to resign for Good Reason (as provided in Section 7(e)(1))); 

(2) if the Executive timely elects continued coverage under COBRA for himself and his covered dependents under the Company’s group
health plans following such termination, then the Company shall pay the COBRA premiums necessary to continue the Executive’s and his covered dependents’ health insurance coverage in effect on the termination date until the earliest of
(i) twelve (12) months following the termination date (the “COBRA Severance Period”); (ii) the date when the Executive becomes eligible for substantially equivalent health insurance coverage in connection with new employment or
self-employment; or (iii) the date the Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination (such period from the termination date through the earlier of (i)-(iii), the “COBRA
Payment Period”). Notwithstanding the foregoing, if at any time the Company determines that its payment of COBRA premiums on the Executive’s behalf would result in a violation of applicable law (including but not limited to the 2010
Patient Protection and Affordable Care Act, as amended by the 2010 Health Care and Education Reconciliation Act), then in lieu of paying COBRA premiums pursuant to this Section 8(d)(2), the Company shall pay the Executive on the last day of
each remaining month of the COBRA Payment Period, a fully taxable cash payment equal to the COBRA premium for such month, subject to applicable tax withholding (such amount, the “Special Severance Payment”), such Special Severance
Payment to be made without regard to the Executive’s payment of COBRA premiums. Nothing in this Agreement shall deprive the Executive of his rights under COBRA or ERISA for benefits under plans and policies arising under his employment by the
Company. 
 (3) in the event that the Executive’s employment is terminated after December 31 of any performance year, but prior
to the Annual Bonus payment date for such performance year, the Executive shall receive: (i) the amount of the Annual Bonus as determined by the Board in good faith for the performance year immediately prior to the year in which the
Executive’s termination occurs if the Company has not determined the amount of the Executive’s Annual Bonus as of the date of the Executive’s termination; or (ii) the amount of the Annual Bonus as already determined by the Board
in good faith for the performance year immediately prior to the year in which the Executive’s termination occurs if the Company has already determined the amount of the Executive’s Annual Bonus as of the date of the Executive’s
termination, payable in either case as a lump sum at the same time annual bonuses are paid to the Company’s executives generally, but no later than March 15 of the calendar year immediately following the calendar year in which the Annual
Bonus is being measured; 
 (4) in the event that the Executive’s employment is terminated: (i) on or before the date Annual
Bonus performance goals are established for the performance year in which the Executive’s termination occurs, the Executive shall receive a pro-rata portion of the Executive’s Target Bonus for the
performance year in which the Executive’s termination occurs, with such pro-rata portion calculated based upon the number of days that the Executive was employed during such performance year divided by
the total number of days in such performance year; or (ii) after the date Annual Bonus performance goals are established for the performance year in which the Executive’s termination occurs (but on or before December 31 of


  
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such performance year), the Executive shall receive a pro-rata portion of the Executive’s Target Bonus for the performance year in which the
Executive’s termination occurs, with such pro-rata portion calculated based upon the Executive’s achievement of performance goals as determined by the Board in good faith, payable in either case as a
lump sum payment on the Company’s first ordinary payroll date occurring on or after the General Release effective date (namely, the date it can no longer be revoked) or as soon thereafter as is reasonable practicable thereafter; and 

(5) twenty-five percent (25%) of the shares subject to all stock options, restricted stock units and other equity awards then held by the
Executive shall vest and become exercisable or payable, as applicable. In addition, the time period that the Executive may have to exercise any stock options shall be extended for a period equal to the shorter of (i) nine (9) months or
(ii) the remaining term of the award. 
 (e) TERMINATION WITHOUT CAUSE OR FOR GOOD REASON FOLLOWING A SIGNIFICANT EVENT. If the
Executive’s employment by the Company is terminated by the Company other than for Cause (and not due to Disability or death), or by the Executive for Good Reason, in either case on or within twenty-four (24) months immediately following a
Significant Event, then the Company shall pay or provide the Executive with the Accrued Amounts and all of the benefits described in Section 8(d) above, subject to compliance with Section 10; provided that: (i) the
Salary Severance Period defined in Section 8(d)(1) shall be increased to a total of eighteen (18) months following the termination date; (ii) the COBRA Severance Period defined in Section 8(d)(2) shall be increased to a total of
eighteen (18) months following the termination date; (iii) in lieu of the pro-rata bonus described in Section 8(d)(4), the Company shall pay the Executive the full Target Bonus for the
performance year in which the Executive’s termination occurs, payable as a lump sum payment on the Company’s first ordinary payroll date occurring on or after the General Release effective date (namely, the date it can no longer be
revoked), and (iv) in lieu of the vesting acceleration described in Section 8(d)(5), all of the outstanding unvested shares subject to stock options, restricted stock units and other equity awards then held by the Executive shall become
fully vested and become exercisable or payable, as applicable, and the time period that the Executive may have to exercise any stock options shall be extended for a period equal to the shorter of (i) twelve (12) months or (ii) the
remaining term of the award.. 
 9. CONDITIONS. Any payments or benefits made or provided pursuant to Section 8 (other
than Accrued Amounts) are subject to the Executive’s (or, in the event of the Executive’s death, the beneficiary’s or estate’s, or in the event of the Executive’s Disability, the guardian’s): 

(a) compliance with the provisions of Section 10 hereof; 

(b) delivery to the Company of the executed Agreement and General Release (the “General Release”), which shall be in the form
attached hereto as Appendix A (with such changes therein or additions thereto as needed under then applicable law to give effect to its intent and purpose) within 21 days following the date of termination of employment, and permitting the General
Release to become effective in accordance with its terms; and 

  
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 (c) delivery to the Company of a resignation from all offices, directorships and fiduciary
positions with the Company, its affiliates and employee benefit plans, by no later than 90 days following termination of employment. 

Notwithstanding the due date of any post-employment payments, any amounts due following a termination under this Agreement (other than Accrued
Amounts) shall not be due until after the expiration of any revocation period applicable to the General Release without the Executive having revoked such General Release, and any such amounts shall be paid or commence being paid to the Executive on
the Company’s first ordinary payroll date occurring on or after the expiration of such revocation period without the occurrence of a revocation by the Executive (or such later date as may be required under Section 17 or the final sentence
of this Section 9). Nevertheless (and regardless of whether the General Release has been executed by the Executive), upon any termination of Executive’s employment, Executive shall be entitled to receive any Accrued Amounts, payable after
the date of termination in accordance with the Company’s applicable plan, program, policy or payroll procedures. Notwithstanding anything to the contrary in this Agreement, if any severance pay or benefits are deferred compensation under
Section 409A (as defined below), and the period during which the Executive may sign the General Release begins in one calendar year and ends in another, then the severance pay or benefit shall not be paid or the first payment shall not occur
until the later calendar year. 
 10. CONFIDENTIALITY AND POST-EMPLOYMENT OBLIGATIONS. As a condition of employment, the
Executive agrees to execute and abide by the Company’s current form of Confidentiality and Non-Competition Agreement (“Confidentiality Agreement”), which may be amended by the parties
from time to time without regard to this Agreement. The Confidentiality Agreement contains provisions that are intended by the parties to survive and do survive termination of this Agreement. 

11. ASSIGNMENT. 

(a) The Executive may not assign or delegate any rights or obligations hereunder without first obtaining the written consent of the Company.

 (b) This Agreement shall be binding upon and inure to the benefit of the Company and its successors, assigns and legal representatives.
The Company will require any acquiror or successor of the Company in any merger, consolidation, sale, or acquisition of the Company, or a similar transaction to assume the Company’s obligations under this Agreement, and any failure to do so
shall constitute a material breach of this Agreement. 
 12. NOTICE. For the purpose of this Agreement, notices and all other
communications provided for in this Agreement shall be in writing and shall be deemed to have been duly given (a) on the date of delivery if delivered by hand, (b) on the date of transmission, if delivered by confirmed facsimile,
(c) on the first business day following the date of deposit if delivered by guaranteed overnight delivery service, or (d) on the fourth business day following the date delivered or mailed by United States registered or certified mail,
return receipt requested, postage prepaid, addressed as follows: If to the Executive: at the address (or to the facsimile number) shown on the records of the Company. 

  
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 If to the Company: 

Eloxx Pharmaceuticals, Inc. 
 950
Winter Street 
 Waltham, MA 02451 
 or to such
other address as either party may have furnished to the other in writing in accordance herewith, except that notices of change of address shall be effective only upon receipt. 

13. SECTION HEADINGS; INCONSISTENCY. The section headings used in this Agreement are included solely for convenience and shall
not affect, or be used in connection with, the interpretation of this Agreement. If there is any inconsistency between this Agreement and any other agreement (including but not limited to any option, stock, long-term incentive or other equity award
agreement), plan, program, policy or practice (collectively, “Other Provision”) of the Company the terms of this Agreement shall control over such Other Provision. 

14. SEVERABILITY. The provisions of this Agreement shall be deemed severable and the invalidity of unenforceability of any
provision shall not affect the validity or enforceability of the other provisions hereof. 
 15. COUNTERPARTS. This Agreement
may be executed in counterparts, each of which shall be deemed to be an original but all of which together will constitute one and the same instruments. One or more counterparts of this Agreement may be delivered by facsimile, with the intention
that delivery by such means shall have the same effect as delivery of an original counterpart thereof. 
 16. MISCELLANEOUS.
No provision of this Agreement may be modified, waived or discharged unless such waiver, modification or discharge is agreed to in writing and signed by the Executive and such officer or director of the Company as may be designated or authorized by
the Board. No waiver by either party hereto at any time of any breach by the other party hereto of, or compliance with, any condition or provision of this Agreement to be performed by such other party shall be deemed a waiver of similar or
dissimilar provisions or conditions at the same or at any prior or subsequent time. This Agreement together with all exhibits hereto and the Confidentiality Agreement sets forth the entire agreement of the parties hereto in respect of the subject
matter contained herein. No agreements or representations, oral or otherwise, express or implied, with respect to the subject matter hereof have been made by either party which are not expressly set forth in this Agreement. The validity,
interpretation, construction and performance of this Agreement shall be governed by the laws of the Commonwealth of Massachusetts without regard to its conflicts of law principles. 

17. SECTION 409A. 

(a) Notwithstanding anything to the contrary herein, the following provisions apply to the extent severance benefits provided herein are
subject to Section 409A of Code and the regulations and other guidance thereunder and any state law of similar effect (collectively “Section 409A”). Severance benefits payable upon a termination of employment
shall not commence until Executive has a “separation from service” for purposes of Section 409A. Each installment of severance benefits is a separate “payment” for purposes of Treas. Reg. Section 1.409A-2(b)(2)(i), 

  
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and the severance benefits are intended to satisfy the exemptions from application of Section 409A provided under Treasury Regulations Sections
1.409A-1(b)(4), 1.409A-1(b)(5) and 1.409A-1(b)(9). However, if such exemptions are not available and Executive is, upon
separation from service, a “specified employee” for purposes of Section 409A, then, solely to the extent necessary to avoid adverse personal tax consequences under Section 409A, the timing of the severance benefits shall be
delayed until the earlier of (i) six (6) months and one day after Executive’s separation from service, or (ii) Executive’s death. Any payment or benefit otherwise payable or to be provided in the six (6) month period
following separation from service that is not so paid or provided by reason of this Section 17 shall be accumulated and paid or provided in a single lump sum, as soon as practicable (and in all events within 15 days) after the date that is six
(6) months after Executive’s separation from service (or, if earlier, as soon as practicable, and in all events within 15 days, after the date of Executive’s death) 

(b) It is intended that this Agreement shall comply with the requirements of Section 409A, and any ambiguity contained herein shall be
interpreted in such manner so as to avoid adverse personal tax consequences under Section 409A. Notwithstanding the foregoing, the Company shall in no event be obligated to indemnify the Executive for any taxes or interest that may be assessed
by the IRS pursuant to Section 409A of the Code on payments made pursuant to this Agreement. 
 18. MITIGATION OF
DAMAGES. In no event shall the Executive be obliged to seek other employment or take any other action by way of mitigation of the severance benefits payable to the Executive under any of the provisions of this Agreement, nor shall the amount
of any severance benefit hereunder be reduced by any compensation earned by the Executive as a result of employment by another employer, except as set forth in this Agreement. 

19. REPRESENTATIONS. The Executive represents and warrants to the Company that the Executive has the legal right to enter into
this Agreement and to perform all of the obligations on the Executive’s part to be performed hereunder in accordance with its terms and that the Executive is not a party to any agreement or understanding, written or oral, which could prevent
the Executive from entering into this Agreement or performing all of the Executive’s obligations hereunder. The Executive further represents and warrants that he has been advised to consult with an attorney and that he has been represented by
the attorney of his choosing during the negotiation of this Agreement (or chosen not to be so represented), that he has consulted with his attorney before executing this Agreement (or chosen not to consult an attorney), that he has carefully read
and fully understand all of the provisions of this Agreement and that he is voluntarily entering into this Agreement. 
 20. NON-DISPARAGEMENT. Both during and after the Employment Term, the Executive and the Company (through its officers and directors) agree not to disparage the other party, and the other party’s officers,
directors, employees, shareholders, affiliates and agents, in any manner likely to be harmful to them or their business, business reputation or personal reputation; provided that both the Executive and the Company may respond
accurately and fully to any question, inquiry or request for information when required by legal process and provided further that nothing in this Section 20 shall preclude any party from making truthful statements that are reasonably necessary
or to enforce or defend the party’s rights under this Agreement. 

  
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 21. WITHHOLDING. The Company may withhold from any and all amounts payable under
this Agreement such federal, state and local taxes as may be required to be withheld pursuant to any applicable law or regulation. 
 22.
SURVIVAL. The respective obligations of, and benefits afforded to, the Company and the Executive which by their express terms or clear intent survive termination of the Executive’s employment with the Company, including, without
limitation, the provisions of Sections 7 through 24, inclusive, of this Agreement, will survive termination of the Executive’s employment with the Company, and will remain in full force and effect according to their terms. 

23. AGREEMENT OF THE PARTIES. The language used in this Agreement will be deemed to be the language chosen by the parties hereto
to express their mutual intent. Neither the Executive nor the Company shall be entitled to any presumption in connection with any determination made hereunder in connection with any arbitration, judicial or administrative proceeding relating to or
arising under this Agreement. 
 24. DISPUTE RESOLUTION. In the event of any controversy, dispute or claim between the parties
under, arising out of or related to this Agreement (including but not limited to, claims relating to breach, termination of this Agreement, or the performance of a party under this Agreement) whether based on contract, tort, statute or other legal
theory (collectively referred to hereinafter as “Disputes”), the parties shall follow the dispute resolution procedures set forth below. Any Dispute shall be finally settled by arbitration in accordance with the Employment
Arbitration Rules & Procedures of JAMS (“JAMS”) then in force, and that the arbitration hearings shall be held in Boston, Massachusetts. The parties agree to (i) appoint an arbitrator who is knowledgeable in employment
and human resource matters and, to the extent possible, the industry in which the Company operates, and instruct the arbitrator to follow substantive rules of law; (ii) require the testimony to be transcribed; and (iii) require the award
to be accompanied by findings of fact and a statement of reasons for the decision. The arbitrator shall have the authority to permit discovery, to the extent deemed appropriate by the arbitrator, upon request of a party, but such discovery process
shall continue for no more than thirty (30) days. The arbitrator shall have no power or authority to add to or detract from the written agreement of the parties. If the parties cannot agree upon an arbitrator within ten (10) days after
demand by either of them, either or both parties may request JAMS name a panel of five (5) arbitrators. The Company shall strike the names of two (2) off this list; then, the Executive shall strike two (2) of the remaining names; and
the remaining name shall be the arbitrator. The Company and the Executive shall each pay for their own attorneys’ fees and expenses and their pro rata share of the JAMS fees and expenses. Any award shall be final, binding and conclusive upon
the parties and a judgment rendered thereon may be entered in any court having jurisdiction thereof. This Section shall not limit the right of any party to sue for injunctive relief for a breach of the obligations of this Agreement. 

[signature page follows] 

  
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 IN WITNESS WHEREOF, the parties hereto have executed this Agreement, effective as of the date
first written above. 
  

			
	 ELOXX PHARMACEUTICALS, INC.

 

	By:	 	 /s/ Robert Ward

		 	Robert Ward
		 	Its: Chief Executive Officer and Director
	
	 EXECUTIVE
  

	 /s/ Pedro Huertas

	 Pedro Huertas



 [Signature Page to Employment Agreement] 







 APPENDIX A 

FORM OF RELEASE 

AGREEMENT AND GENERAL RELEASE 

Eloxx Pharmaceuticals, Inc. (the “Company”) and Pedro Huertas (“Executive”) agree: 

1. Last Day of Employment. Executive’s last day of employment with Employer was [INSERT DATE] (the “Termination
Date”). In addition, effective as of the Termination Date, Executive ceased to serve as Chief Medical Officer of the Company and its affiliates and ceased to be eligible for any benefits or compensation from the Company and its affiliates
other than as specifically provided in Section 7 of the Executive Employment Agreement between the Company and Executive dated as of March 12, 2018 (the “Employment Agreement”). Executive further acknowledges and agrees
that from and after the date Executive executes this Agreement and General Release, Executive will not represent (and since the Termination Date the Executive has not represented) the Executive as being a director, employee, officer, trustee, agent
or representative of the Company or its affiliates for any purpose. In addition, effective as of Termination Date, Executive resigns from all offices, directorships, trusteeships, committee memberships and fiduciary capacities held with, or on
behalf of, the Company and its affiliates or any benefit plans of the Company and its affiliates. These resignations will become irrevocable as set forth in Section 3 below. 

2. Consideration. The parties acknowledge that this Agreement and General Release is being executed in accordance with Section 8
of the Employment Agreement. 
 3. Revocation. Executive may revoke this Agreement and General Release for a period of seven
(7) calendar days following the day Executive executes this Agreement and General Release. Any revocation within this period must be submitted in writing to the Company and state, “I hereby revoke my acceptance of our Agreement and General
Release.” The revocation must be personally delivered to the Chairman of the Board, Eloxx Pharmaceuticals Ltd., 950 Winter Street, Waltham, MA 02451, or his designee. This Agreement and General Release shall become effective and irrevocable on
the eighth (8th) day after Executive executes it, unless earlier revoked by Executive in accordance with this Section 3 (the “Effective Date”). 

4. General Release of Claims. (A) Executive and the Executive’s heirs, executors, administrators, successors and assigns
(collectively referred to throughout this Agreement as “Employee”) knowingly and voluntarily release and forever discharge the Company and its affiliates, subsidiaries, divisions, benefit plans, successors and assigns in such
capacity, and the current, future and former employees, officers, directors, trustees and agents thereof (collectively referred to as “Employer”) from any and all actions, causes of action, contributions, indemnities, duties, debts,
sums of money, suits, controversies, restitutions, understandings, agreements, promises, claims regarding stock, stock options or other forms of equity compensation, commitments, damages, fees and liabilities, responsibilities and any and all
claims, demands, executions and liabilities of whatsoever kind, nature or description, oral or written, known or unknown, matured or unmatured, suspected or unsuspected at the present time, in law or in


  
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equity, whether known and unknown, against Employer, which the Employee has, has ever had or may have as of the date of Executive’s execution of this Agreement and General Release,
including, but not limited to, any alleged violation of: 
  

	 	•	 	Title VII of the Civil Rights Act of 1964, as amended; 

  

	 	•	 	The Civil Rights Act of 1991; 

  

	 	•	 	Sections 1981 through 1988 of Title 42 of the United States Code, as amended; 

  

	 	•	 	The Employee Retirement Income Security Act of 1974, as amended; 

  

	 	•	 	The Immigration Reform and Control Act, as amended; 

  

	 	•	 	The Americans with Disabilities Act of 1990, as amended; 

  

	 	•	 	The Age Discrimination in Employment Act of 1967, as amended; 

  

	 	•	 	The Older Workers Benefit Protection Act of 1990; 

  

	 	•	 	The Worker Adjustment and Retraining Notification Act, as amended; 

  

	 	•	 	The Occupational Safety and Health Act, as amended; 

  

	 	•	 	The Family and Medical Leave Act of 1993; 

  

	 	•	 	The Massachusetts Wage Act; 

  

	 	•	 	Massachusetts anti-discrimination laws, M.G.L Chapter 151B- Any wage payment and collection, equal pay and other similar laws, acts and statutes of the Commonwealth of Massachusetts or the United States;


  

	 	•	 	Any other federal, state or local civil or human rights law or any other local, state or federal law, regulation or ordinance; 

  

	 	•	 	Any public policy, contract, tort, or common law; or 

  

	 	•	 	Any allegation for costs, fees, or other expenses including attorneys’ fees incurred in these matters. 


Notwithstanding anything herein to the contrary, the sole matters to which the Agreement and General Release do not apply are:
(i) Employee’s express rights or claims for accrued vested benefits under any employee benefit plan, policy or arrangement maintained by Employer or under COBRA; (ii) Employee’s rights under the provisions of the Employment
Agreement which are intended to survive termination of employment; or (iii) Employee’s rights as a stockholder; or (iv) any rights of the Executive to indemnification as a Director or Officer of the Company. 

  
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 5. No Claims Permitted. Employee waives Executive’s right to file any charge or
complaint against Employer arising out of Executive’s employment with or separation from Employer before any federal, state or local court or any state or local administrative agency, except where such waivers are prohibited by law (with the
understanding that that this Agreement and General Release bars the Executive from recovering monetary relief from Employer in connection with any charges or complaints which are not waived hereunder). 

Furthermore, nothing in this Agreement or General Release and Waiver of Claims prohibits Executive from reporting possible violations of
federal law or regulation to any governmental agency or entity, including but not limited to the Department of Justice, the Securities and Exchange Commission, the Congress, and any agency Inspector General, or making other disclosures that are
protected under the whistleblower provisions of federal law or regulation. Executive does not need the prior authorization of the Company to make any such reports or disclosures and Executive is not required to notify the Company that Executive has
made such reports or disclosures. 
 6. Affirmations. Employee affirms Executive has not filed, has not caused to be filed, and is
not presently a party to, any claim, complaint, or action against Employer in any forum. Employee further affirms that the Executive has been paid and/or has received all compensation, wages, bonuses, commissions, and/or benefits to which Executive
may be entitled and no other compensation, wages, bonuses, commissions and/or benefits are due to Executive, except as provided in Section 7 of the Employment Agreement. Employee also affirms Executive has no known workplace injuries. 

7. Cooperation; Return of Property. Employee agrees to reasonably cooperate with Employer and its counsel in connection with any
investigation, administrative proceeding or litigation relating to any matter that occurred during Executive’s employment in which Executive was involved or of which Executive has knowledge. Employer will reimburse the Employee for any
reasonable out-of-pocket travel, delivery or similar expenses incurred in providing such service to Employer. Employee represents that Employee has returned to Employer
all property belonging to Employer, including but not limited to any leased vehicle, laptop, cell phone, keys, access cards, phone cards and credit cards, provided that Executive may retain, and Employer shall cooperate in transferring,
Executive’s cell phone number and Executive’s personal rolodex and other address books. 
 8. Governing Law and
Interpretation. This Agreement and General Release shall be governed and conformed in accordance with the laws of the Commonwealth of Massachusetts without regard to its conflict of laws provisions. In the event Employee or Employer breaches any
provision of this Agreement and General Release, Employee and Employer affirm either may institute an action to specifically enforce any term or terms of this Agreement and General Release. Should any provision of this Agreement and General Release
be declared illegal or unenforceable by any court of competent jurisdiction and should the provision be incapable of being modified to be enforceable, such provision shall immediately become null and void, leaving the remainder of this Agreement and
General Release in full force and effect. Nothing herein, however, shall operate to void or nullify any general release language contained in the Agreement and General Release. 

  
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 9. No Admission of Wrongdoing. Employee agrees neither this Agreement and General Release
nor the furnishing of the consideration for this Agreement and General Release shall be deemed or construed at any time for any purpose as an admission by Employer of any liability or unlawful conduct of any kind. 

10. Non-Disparagement. Employee and Employer (through its officers and directors) agree not to
disparage the other party, and the other party’s officers, directors, employees, shareholders and agents, in any manner likely to be harmful to them or their business, business reputation or personal reputation; provided that both
Employee and Employer may respond accurately and fully to any question, inquiry or request for information when required by legal process and provided further that nothing in this Section 10 shall preclude Employer or Employee
from making truthful statements that are reasonably necessary or to enforce or defend the party’s rights under this Agreement and General Release. 

11. Amendment. This Agreement and General Release may not be modified, altered or changed except upon express written consent of both
parties wherein specific reference is made to this Agreement and General Release. 
 12. Entire Agreement. This Agreement and General
Release and the Confidentiality Agreement (as defined in the Employment Agreement) sets forth the entire agreement between the parties hereto and fully supersedes any prior agreements or understandings between the parties; provided,
however, that notwithstanding anything in this Agreement and General Release, the provisions in the Employment Agreement which are intended to survive termination of the Employment Agreement, including but not limited to those contained in
Section 10 thereof, shall survive and continue in full force and effect. Employee acknowledges Executive has not relied on any representations, promises, or agreements of any kind made to Executive in connection with Executive’s decision
to accept this Agreement and General Release. 
 13. ADEA. Employee understands and acknowledges that Employee is waiving and
releasing any rights Executive may have under the Age Discrimination in Employment Act of 1967 (“ADEA”), and that this waiver and release is knowing and voluntary. Employee understands and agrees that this waiver and release does
not apply to any rights or claims that may arise under the ADEA after the date Executive signs this Agreement and General Release. Employee understands and acknowledges that the consideration given for this waiver and release is in addition to
anything of value to which Employee was already entitled. Employee further understands and acknowledges that Employee has been advised by this writing that nothing in this Agreement prevents or precludes Executive from challenging or seeking a
determination in good faith of the validity of this waiver under the ADEA, nor does it impose any condition precedent, penalties, or costs for doing so, unless specifically authorized by federal law. 

[signature page follows] 

  
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 EMPLOYEE HAS BEEN ADVISED THAT EXECUTIVE HAS UP TO
TWENTY-ONE (21) CALENDAR DAYS TO REVIEW THIS AGREEMENT AND GENERAL RELEASE AND HAS BEEN ADVISED IN WRITING TO CONSULT WITH AN ATTORNEY PRIOR TO EXECUTION OF THIS AGREEMENT AND GENERAL RELEASE. 

EMPLOYEE AGREES ANY MODIFICATIONS, MATERIAL OR OTHERWISE, MADE TO THIS AGREEMENT AND GENERAL RELEASE DO NOT RESTART OR AFFECT IN ANY MANNER
THE ORIGINAL TWENTY-ONE (21) CALENDAR DAY CONSIDERATION PERIOD. IN THE EVENT EMPLOYEE SIGNS THIS AGREEMENT AND GENERAL RELEASE AND RETURNS IT TO THE COMPANY IN LESS THAN THE
TWENTY-ONE (21) DAY PERIOD IDENTIFIED ABOVE, EMPLOYEE HEREBY ACKNOWLEDGES THAT EMPLOYEE HAS FREELY AND VOLUNTARILY CHOSEN TO WAIVE THE TIME PERIOD ALLOTTED FOR CONSIDERING THIS AGREEMENT AND GENERAL
RELEASE. 
 HAVING ELECTED TO EXECUTE THIS AGREEMENT AND GENERAL RELEASE, TO FULFILL THE PROMISES SET FORTH HEREIN, AND TO RECEIVE THE SUMS
AND BENEFITS SET FORTH IN THE EMPLOYMENT AGREEMENT, EMPLOYEE FREELY AND KNOWINGLY, AND AFTER DUE CONSIDERATION, ENTERS INTO THIS AGREEMENT AND GENERAL RELEASE INTENDING TO WAIVE, SETTLE AND RELEASE ALL CLAIMS EXECUTIVE HAS OR MIGHT HAVE AGAINST
EMPLOYER. 
 IN WITNESS WHEREOF, the parties hereto knowingly and voluntarily executed this Agreement and General Release as of the date set
forth below: 
  

			
	 ELOXX PHARMACEUTICALS, INC.

		
	By:	 	  

		 	Name: Robert E. Ward
		 	Its: Chairman & CEO
		
		 	Date: 
	
	EXECUTIVE
	
	  

	Pedro Huertas
	
	Date: