Exhibit 10.8

ARMO BIOSCIENCES

October 26, 2017

Herb Cross

[Address]

Re: Employment Offer; Employment Agreement

Dear Herb:

ARMO BioSciences, Inc. (the “Company”) is pleased to offer you employment on the following terms:

1.    Position. Your initial title will be Chief Financial Officer, and you will report to the Company’s Chief Executive Officer. This is a full-time position. You will be responsible for the establishment of a highly competitive team and supervise all activities related to finance and other related activities including, but not limited to IT and facilities, at the Company. As the company grows, your responsibilities may change. While you render services to the Company, you will not engage in any other employment, consulting or other business activity (whether full-time or part-time) that would create a conflict of interest with the Company. By signing this letter agreement, you confirm to the Company that you have no contractual commitments or other legal obligations that would prohibit you from performing your duties for the Company.

2.    Cash Compensation. You will earn a monthly salary in the gross amount of $25,833.33 which is equivalent to $310,000 on an annualized basis. Your salary will be payable pursuant to the Company’s regular payroll schedule (or in the same manner as other officers of the Company), and will be subject to tax and other required withholdings.

You will be eligible to earn an annual bonus up to 35% of the amount of base salary actually paid to you during that calendar year. The precise amount of such bonus will be determined by the Board, based on the extent to which the Company meets minimum and exceeds minimum performance-related goals proposed by management and approved by the Board for the Company’s fiscal year ending December 31. The determinations of the Company’s Board of Directors with respect to your bonus will be final and binding.

Any bonus for a fiscal year will be paid within 2¹/₂ months after the close of that fiscal year, but only if you are still employed by the Company at the time of payment.

3.    Employee Benefits. As a regular employee of the Company, you will be eligible to participate in a number of Company-sponsored benefits. In addition, you will be entitled to paid vacation in accordance with the Company’s vacation policy, as in effect from time to time.

Herb Cross

October 26, 2017

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4.    Stock Options. Subject to the approval of the Company’s Board of Directors or its Compensation Committee, you will be granted an option to purchase 1,133,331 shares of the Company’s Common Stock (the “Option”). The exercise price per share of the Option will be the fair market value of the Company’s common stock as determined by the Board of Directors or the Compensation Committee when the Option is granted. The Option will be subject to the terms and conditions applicable to options granted under the Company’s Stock Plan (the “Plan”), as described in the Plan and the applicable Stock Option Agreement. You will vest 25% of the Option shares after 12 months of continuous service, and the balance will vest in equal monthly installments over the next 36 months of continuous service, as described in the applicable Stock Option Agreement. The Option will be immediately exercisable, but in the event that your service terminates for any reason before you vest in the shares, the unvested portion of the purchased shares will be subject to repurchase by the Company pursuant to the terms of the Plan.

5.    Severance Benefits.

(a)    General. If you are subject to a Termination Without Cause, then you will be entitled to the benefits described in this Section 5. However, this Section 5 will not apply unless you (i) have returned all Company property in your possession and (ii) have executed a general release of all claims that you may have against the Company or persons affiliated with the Company. The release must be in the form prescribed by the Company, without alterations. You must execute and return the release on or before the date specified by the Company in the prescribed form (the “Release Deadline”). The Release Deadline will in no event be later than 50 days after your Separation. If you fail to return the release on or before the Release Deadline, or if you revoke the release, then you will not be entitled to the benefits described in this Section 5.

(b)    Salary Continuation. If you are subject to a Termination Without Cause, then the Company will continue to pay your base salary for a period of six months after your Separation. Your base salary will be paid at the rate in effect at the time of your Separation and in accordance with the Company’s standard payroll procedures. The salary continuation payments will commence within 60 days after your Separation and, once they commence, will include any unpaid amounts accrued from the date of your Separation. However, if the 60-day period described in the preceding sentence spans two calendar years, then the payments will in any event begin in the second calendar year.

(c)    COBRA. If you are subject to a Termination Without Cause and you elect to continue your health insurance coverage under the Consolidated Omnibus Budget Reconciliation Act (“COBRA”) following your Separation, then the Company will pay the same portion of your monthly premium under COBRA as it pays for active employees and their eligible dependents until the earliest of (i) the close of the six-month period following your Separation, (ii) the expiration of your continuation coverage under COBRA or (iii) the date when you become eligible for substantially equivalent health insurance coverage in connection with new employment. Notwithstanding the foregoing if the Company determines in its sole discretion that it cannot provide the preceding benefit without potentially violating, or being subject to an excise tax under, applicable law (including, without limitation, Section 2716 of the

Herb Cross

October 26, 2017

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Public Health Service Act), the Company will in lieu thereof provide to you a taxable monthly payment in an amount equal to the monthly COBRA premium that you would be required to pay to continue your group health coverage in effect on the termination of employment date (which amount will be based on the premium for the first month of COBRA coverage), which payments will be made regardless of whether you elect COBRA continuation coverage and will commence on the month following your Separation and will end on the earlier of (x) the date upon which you obtain other employment or (y) the date the Company has paid an amount equal to six (6) months. For the avoidance of doubt, the taxable payments in lieu of COBRA reimbursements may be used for any purpose, including, but not limited to continuation coverage under COBRA, and will be subject to all applicable tax withholding.

(d)    Accelerated Vesting. If you are subject to a Termination Without Cause prior to a Change in Control, then the vested percentage of the shares subject to the Option will be determined by adding six months to the actual period of service that you have completed with the Company. Further, you will vest in 100% of your remaining unvested Option shares if (a) the Company is subject to a Change in Control before your continuous service with the Company terminates and (b) you are subject to an Involuntary Termination within 12 months after that Change in Control.

6.    Proprietary Information and Inventions Agreement. Like all Company employees, you will be required, as a condition of your employment with the Company, to sign the Company’s standard Proprietary Information and Inventions Agreement, a copy of which is attached hereto as Exhibit A.

7.    Employment Relationship. Employment with the Company is for no specific period of time. Your employment with the Company will be “at will,” meaning that either you or the Company may terminate your employment at any time and for any reason, with or without cause. Any contrary representations that may have been made to you are superseded by this letter agreement. This is the full and complete agreement between you and the Company on this term. Although your job duties, title, compensation and benefits, as well as the Company’s personnel policies and procedures, may change from time to time, the “at will” nature of your employment may only be changed in an express written agreement signed by you and a duly authorized officer of the Company (other than you).

8.    Tax Matters.

(a)    Withholding. All forms of compensation referred to in this letter agreement are subject to reduction to reflect applicable withholding and payroll taxes and other deductions required by law.

(b)    Tax Advice. You are encouraged to obtain your own tax advice regarding your compensation from the Company. You agree that the Company does not have a duty to design its compensation policies in a manner that minimizes your tax liabilities, and you will not make any claim against the Company or its Board of Directors related to tax liabilities arising from your compensation.

Herb Cross

October 26, 2017

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9.    Interpretation, Amendment and Enforcement. This letter agreement and Exhibit A supersede and replace any prior agreements, representations or understandings (whether written, oral, implied or otherwise) between you and the Company and constitute the complete agreement between you and the Company regarding the subject matter set forth herein. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company (the “Disputes”) will be governed by California law, excluding laws relating to conflicts or choice of law. You and the Company submit to the exclusive personal jurisdiction of the federal and state courts located in California in connection with any Dispute or any claim related to any Dispute.

10.    Definitions. The following terms have the meaning set forth below wherever they are used in this letter agreement:

“Cause” means your (i) unauthorized use or disclosure of the Company’s confidential information or trade secrets, which use or disclosure causes material harm to the Company; (ii) material breach of any agreement with the Company; (iii) material failure to comply with the Company’s written policies or rules; (iv) conviction of, or plea of “guilty” or “no contest” to, a felony under the laws of the United States or any state thereof; (v) gross negligence or willful misconduct; (vi) continuing failure to perform assigned duties after receiving written notification of such failure from the Board of Directors; or (vii) failure to cooperate in good faith with a governmental or internal investigation of the Company or its directors, officers or employees, if the Company has requested your cooperation.

“Change in Control” means (i) the consummation of a sale, merger or consolidation of the Company with or into another entity or (ii) the dissolution, liquidation or winding up of the Company. The foregoing notwithstanding, a sale, merger or consolidation of the Company shall not constitute a “Corporate Transaction” if immediately after such sale, merger or consolidation a majority of the voting power of the capital stock of the continuing or surviving entity, or any direct or indirect parent corporation of such continuing or surviving entity, will be owned by the persons who were the Company’s stockholders immediately prior to such sale, merger or consolidation in substantially the same proportions as their ownership of the voting power of the Company’s capital stock immediately prior to such merger or consolidation..

“Involuntary Termination” means either (a) your Termination Without Cause or (b) your Resignation for Good Reason.

“Resignation for Good Reason” means that you resign within 12 months after one of the following conditions has come into existence without your consent: (i) a reduction in your base salary by more than 10%; (ii) a material diminution of your authority, duties or responsibilities; or (iii) a relocation of your principal workplace by more than 30 miles. A condition shall not be considered “Good Reason” unless you give the Company written notice of such condition within 90 days after such condition comes into existence and the Company fails to remedy such condition within 30 days after receiving your written notice.

Herb Cross

October 26, 2017

Page 5

“Separation” means a “separation from service,” as defined in the regulations under Section 409A of the Code.

“Termination Without Cause” means a Separation as a result of a termination of your employment by the Company without Cause, provided you are willing and able to continue performing services within the meaning of Treasury Regulation 1.409A-1(n)(1).

* * * * *

We hope that you will accept our offer to join the Company. You may indicate your agreement with these terms and accept this offer by signing and dating both the enclosed duplicate original of this letter agreement and the enclosed Proprietary Information and Inventions Agreement and returning them to me. As required by law, your employment with the Company is contingent upon your providing legal proof of your identity and authorization to work in the United States.

The start date of your employment at the Company is November 27, 2017. Please discuss with the CEO in case this date is not feasible.

Attachment

Exhibit A: Proprietary Information and Inventions Agreement

PROPRIETARY INFORMATION AND INVENTIONS AGREEMENT

The following confirms and memorializes an agreement that ARMO Biosciences, Inc., a Delaware corporation (the “Company”) and I (Herb Cross) have had since the commencement of my employment (which term, for purposes of this agreement, shall be deemed to include any relationship of service to the Company that I may have had prior to actually becoming an employee) with the Company in any capacity and that is and has been a material part of the consideration for my employment by Company:

1.    I have not entered into, and I agree I will not enter into, any agreement either written or oral in conflict with this Agreement or my employment with Company. I will not violate any agreement with or rights of any third party or, except as expressly authorized by Company in writing hereafter, use or disclose my own or any third party’s confidential information or intellectual property when acting within the scope of my employment or otherwise on behalf of Company. Further, I have not retained anything containing any confidential information of a prior employer or other third party, whether or not created by me.

2.    Company shall own all right, title and interest (including patent rights, copyrights, trade secret rights, mask work rights, sui generis database rights and all other intellectual property rights of any sort throughout the world) relating to any and all inventions (whether or not patentable), works of authorship, mask works, designs, know-how, ideas and information made or conceived or reduced to practice, in whole or in part, by me during the term of my employment with Company to and only to the fullest extent allowed by California Labor Code Section 2870 (which is attached as Appendix A) (collectively “Inventions”) and I will promptly disclose all Inventions to Company. Without disclosing any third party confidential information, I will also disclose anything I believe is excluded by Section 2870 so that the Company can make an independent assessment. I hereby make all assignments necessary to accomplish the foregoing. I shall further assist Company, at Company’s expense, to further evidence, record and perfect such assignments, and to perfect, obtain, maintain, enforce, and defend any rights specified to be so owned or assigned. I hereby irrevocably designate and appoint Company as my agent and attorney-in-fact, coupled with an interest and with full power of substitution, to act for and in my behalf to execute and file any document and to do all other lawfully permitted acts to further the purposes of the foregoing with the same legal force and effect as if executed by me. Without limiting Section 1 or Company’s other rights and remedies, if, when acting within the scope of my employment or otherwise on behalf of Company, I use or disclose my own or any third party’s confidential information or intellectual property (or if any Invention cannot be fully made, used, reproduced, distributed and otherwise exploited without using or violating the foregoing), Company will have and I hereby grant Company a perpetual, irrevocable, worldwide royalty-free, non-exclusive, sublicensable right and license to exploit and exercise all such confidential information and intellectual property rights.

3.    To the extent allowed by law, paragraph 2 includes all rights of paternity, integrity, disclosure and withdrawal and any other rights that may be known as or referred to as “moral rights,” “artist’s rights,” “droit moral,” or the like (collectively “Moral Rights”). To the extent I retain any such Moral Rights under applicable law, I hereby ratify and consent to any action that may be taken with respect to such Moral Rights by or authorized by Company and agree not to assert any Moral Rights with respect thereto. I will confirm any such ratifications, consents and agreements from time to time as requested by Company.

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4.    I agree that all Inventions and all other business, technical and financial information (including, without limitation, the identity of and information relating to customers or employees) I develop, learn or obtain during the term of my employment that relate to Company or the business or demonstrably anticipated business of Company or that are received by or for Company in confidence, constitute “Proprietary Information.” I will hold in confidence and not disclose or, except within the scope of my employment, use any Proprietary Information. However, I shall not be obligated under this paragraph with respect to information I can document is or becomes readily publicly available without restriction through no fault of mine. Upon termination of my employment, I will promptly return to Company all items containing or embodying Proprietary Information (including all copies), except that I may keep my personal copies of (i) my compensation records, (ii) materials distributed to shareholders generally and (iii) this Agreement. I also recognize and agree that I have no expectation of privacy with respect to Company’s telecommunications, networking or information processing systems (including, without limitation, stored computer files, email messages and voice messages) and that my activity and any files or messages on or using any of those systems may be monitored at any time without notice.

5.    Until one year after the term of my employment, I will not encourage or solicit any employee or consultant of Company to leave Company for any reason (except for the bona fide firing of Company personnel within the scope of my employment).

6.    I agree that during the term of my employment with Company (whether or not during business hours), I will not engage in any activity that is in any way competitive with the business or demonstrably anticipated business of Company, and I will not assist any other person or organization in competing or in preparing to compete with any business or demonstrably anticipated business of Company.

7.    I agree that this Agreement is not an employment contract for any particular term and that I have the right to resign and Company has the right to terminate my employment at will, at any time, for any or no reason, with or without cause. In addition, this Agreement does not purport to set forth all of the terms and conditions of my employment, and, as an employee of Company, I have obligations to Company which are not set forth in this Agreement. However, the terms of this Agreement govern over any inconsistent terms and can only be changed by a subsequent written agreement signed by the President of Company.

8.    I agree that my obligations under paragraphs 2, 3, 4 and 5 of this Agreement shall continue in effect after termination of my employment, regardless of the reason or reasons for termination, and whether such termination is voluntary or involuntary on my part, and that Company is entitled to communicate my obligations under this Agreement to any future employer or potential employer of mine. My obligations under paragraphs 2, 3 and 4 also shall be binding upon my heirs, executors, assigns, and administrators and shall inure to the benefit of Company, its subsidiaries, successors and assigns.

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9.    Any dispute in the meaning, effect or validity of this Agreement shall be resolved in accordance with the laws of the State of California without regard to the conflict of laws provisions thereof. I further agree that if one or more provisions of this Agreement are held to be illegal or unenforceable under applicable California law, such illegal or unenforceable portion(s) shall be limited or excluded from this Agreement to the minimum extent required so that this Agreement shall otherwise remain in full force and effect and enforceable in accordance with its terms. This Agreement is fully assignable and transferable by Company, but any purported assignment or transfer by me is void. I also understand that any breach of this Agreement will cause irreparable harm to Company for which damages would not be an adequate remedy, and, therefore, Company will be entitled to injunctive relief with respect thereto in addition to any other remedies and without any requirement to post bond.

NOTICE: This agreement does not affect any immunity under 18 USC Sections 1833(b) (1) or (2), which read as follows (note that for purposes of this statute only, individuals performing work as contractors or consultants are considered to be employees):

(1)    An individual shall 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 filed in a lawsuit or other proceeding, if such filing is made under seal.

(2)    An individual who files a lawsuit for retaliation by an employer for reporting a suspected violation of law may disclose the trade secret to the attorney of the individual 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.

I HAVE READ THIS AGREEMENT CAREFULLY AND I UNDERSTAND AND ACCEPT THE OBLIGATIONS WHICH IT IMPOSES UPON ME WITHOUT RESERVATION. NO PROMISES OR REPRESENTATIONS HAVE BEEN MADE TO ME TO INDUCE ME TO SIGN THIS AGREEMENT. I SIGN THIS AGREEMENT VOLUNTARILY AND FREELY, IN DUPLICATE, WITH THE UNDERSTANDING THAT THE COMPANY WILL RETAIN ONE COUNTERPART AND THE OTHER COUNTERPART WILL BE RETAINED BY ME.

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APPENDIX A

California Labor Code Section 2870. Application of provision providing that employee shall assign or offer to assign rights in invention to employer.

(a)    Any provision in an employment agreement which provides that an employee shall assign, or offer to assign, any of his or her rights in an invention to his or her employer shall not apply to an invention that the employee developed entirely on his or her own time without using the employer’s equipment, supplies, facilities, or trade secret information except for those inventions that either:

(1)    Relate at the time of conception or reduction to practice of the invention to the employer’s business, or actual or demonstrably anticipated research or development of the employer; or

(2)    Result from any work performed by the employee for his employer.

(b)    To the extent a provision in an employment agreement purports to require an employee to assign an invention otherwise excluded from being required to be assigned under subdivision (a), the provision is against the public policy of this state and is unenforceable.