SEPARATION AGREEMENT This Separation Agreement (the Agreement ) by and between Vincent O Neill ( Executive ) and Mirna Therapeutics, Inc., a Delaware corporation (the Company ), is made effective eight (8) days after Exe

SEPARATION AGREEMENT

This Separation Agreement (the Agreement ) by and between Vincent O Neill ( Executive ) and Mirna

Therapeutics, Inc., a Delaware corporation (the Company ), is made effective eight (8) days after Executive s signature hereto (the Effective Date ), unless Executive revokes his acceptance of this

Agreement as provided in Section 5(c) below, with reference to the following facts:

A. Executive s employment with the Company

and status as an officer and employee of the Company and each of its affiliates will end effective upon the Separation Date (as defined below).

B. Executive and the Company want to end their relationship amicably and also to establish the obligations of the parties including, without

limitation, all amounts due and owing to Executive.

C. The payments and benefits being made available to Executive pursuant to this

Agreement are intended to satisfy all outstanding obligations under that certain Change in Control Severance Agreement by between Executive and the Company (the Severance Agreement ).

NOW, THEREFORE, in consideration of the mutual covenants and agreements hereinafter set forth, the parties agree as follows:

1. Separation Date. Executive acknowledges and agrees that his status as an officer and employee of the Company will end effective as of

May 19, 2017 (the Separation Date ). Executive hereby agrees to execute such further document(s) as shall be determined by the Company as necessary or desirable to give effect to the end of Executive s status as an

officer of the Company and, if applicable, officer and/or director of any of its subsidiaries; provided that such documents shall not be inconsistent with any of the terms of this Agreement.

2. Final Paycheck; Payment of Accrued Wages and Expenses.

(a) Final Paycheck. As soon as administratively practicable on or after the Separation Date, the Company will pay

Executive all accrued but unpaid base salary and all accrued and unused vacation earned through the Separation Date, subject to standard payroll deductions and withholdings. Executive is entitled to these payments regardless of whether Executive

executes this Agreement.

(b) Business Expenses. The Company shall reimburse Executive for all outstanding expenses

incurred prior to the Separation Date which are consistent with the Company s policies in effect from time to time with respect to travel, entertainment and other business expenses, subject to the Company s requirements with respect to

reporting and documenting such expenses, including, without limitation, expenses incurred pursuant to Executive s services as a director of any of the Company s subsidiaries.

3. Separation Payments and Benefits. Without admission of any liability, fact or claim, the Company hereby agrees, subject to this

Agreement becoming effective and irrevocable, as well as Executive s performance of his continuing obligations pursuant to this Agreement and that certain Confidentiality, Covenant Not To Compete & Arbitration Agreement by and between

the Company and Executive dated April 11, 2016 (the Confidentiality Agreement ) (including, without limitation, the non-competition and non-solicitation restrictive covenants set forth therein for the

periods set forth in the Confidentiality Agreement), to provide Executive the severance benefits set forth below. Specifically, the Company and Executive agree as follows:

(a) Severance. The Company shall pay to Executive four hundred fifty-nine thousand dollars ($459,000), which represents

the sum of (i) twelve (12) months of Executive s annual base salary and (ii) one (1) times Executive s target annual bonus assuming achievement of performance goals at target, in each case, at the rate in effect

immediately prior to the Separation Date, in a single cash lump sum. Such payment shall be made, less applicable withholdings and deductions, on or as soon as reasonably practicable following the first regularly scheduled payroll date following the

date this Agreement becomes effective and irrevocable.

(b) Healthcare Continuation Coverage. If Executive

elects to receive continued healthcare coverage pursuant to the provisions of the Consolidated Omnibus Budget Reconciliation Act of 1985, as amended ( COBRA ), the Company shall directly pay, or reimburse Executive for, that

portion of the premium for Executive and Executive s covered dependents necessary such that Executive contributes the same amount to COBRA coverage as Executive contributed to medical, dental and vision coverage prior to the date of this

Agreement, such payment or reimbursement to continue until the earlier of (i) the last day of the twelfth (12th) full calendar month anniversary following the date this Agreement becomes

effective and irrevocable or (ii) the date Executive becomes eligible for comparable coverage under another employer s plans. After the Company ceases to pay premiums pursuant to the preceding sentence, Executive may, if eligible, elect to

continue healthcare coverage at Executive s expense in accordance with the provisions of COBRA. Executive acknowledges that he shall be solely responsible for all matters relating to Executive s continuation of coverage pursuant to COBRA,

including, without limitation, Executive s election of such coverage and his timely payment of premiums.

Equity Awards. Each outstanding and unvested equity award, including, without limitation, each stock option and restricted stock award, held by Executive (collectively, the Equity Awards ) shall become vested and, if

applicable, exercisable and any forfeiture restrictions or rights of repurchase thereon shall immediately lapse, in each case, with respect to one hundred percent (100%) of that number of unvested shares underlying the Equity Awards as of the

Separation Date. The Equity Awards shall otherwise be subject to the terms of the applicable award agreements (the Equity Award Agreements ).

(d) Taxes. Executive understands and agrees that all payments under this Section 3 will be subject to appropriate

tax withholding and other deductions. To the extent any taxes may be payable by Executive for the benefits provided to him by this Section 3 beyond those withheld by the Company, Executive agrees to pay them himself and to indemnify and hold

the Company and the other entities released herein harmless for any tax claims or penalties, and associated attorneys fees and costs, resulting from any failure by him to make required payments. To the extent that any reimbursements payable

pursuant to this Agreement are subject to the provisions of Section 409A of the Internal Revenue Code of 1986, as amended (the Code ), such reimbursements shall be paid to Executive no later than December 31 of the year

following the year in which the expense was incurred, the amount of expenses reimbursed in one year shall not affect the amount eligible for reimbursement in any subsequent year, and Executive s right to reimbursement under this Agreement will

not be subject to liquidation or exchange for another benefit.

(e) SEC Reporting. Executive acknowledges that to the extent

required by the Securities Exchange Act of 1934, as amended (the Exchange Act ), he will have continuing obligations under Section 16(a) and 16(b) of the Exchange Act to report Executive s matching transactions in Company

common stock for six (6) months following the Separation Date. Executive hereby agrees not to undertake, directly or indirectly, any reportable transactions involving the common stock of the Company until the end of such six (6) month

(f) Sole Separation Benefit. Executive agrees that the payments provided by this

Section 3 are not required under the Company s normal policies and procedures and are provided as a severance solely in connection with this Agreement. Executive acknowledges and agrees that the payments referenced in this Section 3

constitute adequate and valuable consideration, in and of themselves, for the promises contained in this Agreement.

Payment. Executive acknowledges that the payment and arrangements herein shall constitute full and complete satisfaction of any and all amounts properly due and owing to Executive as a result of his employment with the Company and the

termination thereof. Executive further acknowledges that, other than the Equity Award Agreements, the Confidentiality Agreement and the Indemnification Agreement between Executive and the Company (the Indemnification Agreement ),

this Agreement shall supersede each agreement entered into between Executive and the Company regarding Executive s employment, including, without limitation, any offer letter, the Severance Agreement and that certain employment agreement by and

between Executive and the Company dated April 25, 2016, and each such agreement shall be deemed terminated and of no further effect as of the Separation Date.

5. Executive s Release of the Company. Executive understands that by agreeing to the release provided by this Section 5,

Executive is agreeing not to sue, or otherwise file any claim against, the Company or any of its employees or other agents for any reason whatsoever based on anything that has occurred as of the date Executive signs this Agreement.

(a) On behalf of Executive and Executive s heirs, assigns, executors, administrators, trusts, spouse and estate, Executive

hereby releases and forever discharges the Releasees hereunder, consisting of the Company, and each of its owners, affiliates, subsidiaries, predecessors, successors, assigns, agents, directors, officers, partners, employees, and

insurers, and all persons acting by, through, under or in concert with them, or any of them, of and from any and all manner of action or actions, cause or causes of action, in law or in equity, suits, debts, liens, contracts, agreements, promises,

liability, claims, demands, damages, loss, cost or expense, of any nature whatsoever, known or unknown, fixed or contingent (hereinafter called Claims ), which Executive now has or may hereafter have against the Releasees, or any

of them, by reason of any matter, cause, or thing whatsoever from the beginning of time to the date hereof, including, without limiting the generality of the foregoing, any Claims arising out of, based upon, or relating to Executive s hire,

employment, remuneration or resignation by the Releasees, or any of them, Claims arising under federal, state, or local laws relating to employment, Claims of any kind that may be brought in any court or administrative agency, including any Claims

arising under the Age Discrimination in Employment Act ( ADEA ), 29 U.S.C. 621, et seq.; Title VII of the Civil Rights Act of 1964, as amended by the Civil Rights Act of 1991, 42 U.S.C. 2000 et

seq.; the Equal Pay Act, 29 U.S.C. 206(d); the Civil Rights Act of 1866, 42 U.S.C. 1981; the Family and Medical Leave Act of 1993, 29 U.S.C. 2601 et seq.; the Americans with Disabilities Act of

1990, 42 U.S.C. 12101 et seq.; the False Claims Act , 31 U.S.C.

3729 et seq.; the Employee Retirement Income Security Act, 29 U.S.C. 1001 et seq.; the Worker Adjustment and Retraining Notification Act, 29 U.S.C. 2101 et

seq. the Fair Labor Standards Act, 29 U.S.C. 215 et seq., the Sarbanes-Oxley Act of 2002; the Texas Labor Code, including the Texas Commission on Human Rights Act; Section 451.001 of the Texas Workers Compensation Act;

the Texas Payday Act; and the Texas Labor Code; Claims for breach of contract; Claims arising in tort, including, without limitation, Claims of wrongful dismissal or discharge, discrimination, harassment, retaliation, fraud, misrepresentation,

defamation, libel, infliction of emotional distress, violation of public policy, and/or breach of the implied covenant of good faith and fair dealing; and Claims for damages or other remedies of any sort, including, without limitation, compensatory

damages, punitive damages, injunctive relief and attorney s fees.

(b) Notwithstanding the generality of the

foregoing, Executive does not release the following claims:

(i) Claims for unemployment compensation or any state

disability insurance benefits pursuant to the terms of applicable state law;

(ii) Claims for workers compensation

insurance benefits under the terms of any worker s compensation insurance policy or fund of the Company;

Claims to continued participation in certain of the Company s group benefit plans pursuant to the terms and conditions of COBRA;

(iv) Claims to any benefit entitlements vested as the date of Executive s employment termination, pursuant to written

terms of any Company employee benefit plan;

(v) Claims for indemnification under the Indemnification Agreement, the

Company s Bylaws or any applicable law; and

(vi) Executive s right to bring to the attention of the Equal

Employment Opportunity Commission claims of discrimination; provided, however, that Executive does release Executive s right to secure any damages for alleged discriminatory treatment.

(c) In accordance with the Older Workers Benefit Protection Act of 1990, Executive has been advised of the following:

Executive acknowledges that Executive is knowingly and voluntarily waiving and releasing any rights Executive may have under the ADEA. Executive also acknowledges that the consideration given for the waiver and release herein is in addition to

anything of value to which Executive was already entitled. Executive further acknowledges that Executive has been advised by this writing, as required by the ADEA, that: (i) Executive s waiver and release do not apply to any rights or

claims that may arise after the execution date of this Agreement; (ii) Executive has been advised hereby that Executive has the right to consult with an attorney prior to executing this Agreement; (iii) Executive has forty-five

(45) days from the date of this Agreement to execute this Agreement (although Executive may choose to voluntarily execute this Agreement earlier); (iv) Executive has received with this Agreement a detailed list of the job titles and ages

of all employees who were terminated in this group termination and the ages of all employees of the Company in the same job classification or organizational unit who were not terminated, attached hereto as Appendix A; (v) Executive has seven

(7) days following the execution of

this Agreement by Executive to revoke the Agreement, and Executive will not receive the severance benefits provided by Section 3 of this Agreement unless and until such seven (7) day

period has expired; (vi) this Agreement will not be effective until the date upon which the revocation period has expired, which will be the eighth (8th) day after this Agreement is

executed by Executive, provided that the Company has also executed this Agreement by that date; and (vii) this Agreement does not affect Executive s ability to test the knowing and voluntary nature of this Agreement. If Executive

wishes to revoke this Agreement, Executive must deliver notice of Executive s revocation in writing, no later than 5:00 p.m. Central Time on the 7th day following Executive s execution of this Agreement to Alan Fuhrman, P.O Box 163387,

Austin, TX 78716, or e-mail: afuhrman@mirnarx.com.

6. Non-Disparagement, Transition, Transfer of Company Property and Limitations on

Service. Both parties further agree that:

(a) Non-Disparagement. Both parties agree that they shall not

disparage, criticize or defame the other party and their respective directors, officers, agents, partners, stockholders, employees, products, services, technology or business, either publicly or privately. Nothing in this Section 6(a) shall