Exhibit 10.8

Juno Therapeutics, Inc.

307 Westlake Avenue North, Suite 300

Seattle, WA 98109

May 27, 2015

Hyam Levitsky, M.D.

[omitted]

Dear Hy:

I am pleased to offer you a position with Juno Therapeutics, Inc. (the
“Company”) as Executive Vice President, Research and Chief Scientific Officer,
reporting to Hans Bishop, President and Chief Executive Officer, effective as of
May 27, 2015 (the “Start Date”). Commencing on the Start Date, and during your
employment with the Company, you will receive an annual base salary of $400,000,
which will be paid semi-monthly in accordance with the Company’s normal payroll
procedures. As an employee, you also will be eligible to participate in the
employee benefit plans maintained by the Company of general applicability to
other employees of the Company.

You will be offered the opportunity to earn an annual incentive bonus (the
“Bonus”) with a target equal to 40% of your annual base salary (the “Target”)
upon attainment of certain performance objectives to be determined by the Board
of Directors of the Company (the “Board”), which Bonus will be prorated in 2015
based on the portion of the year served as an employee. The achievement of such
objectives will be determined by the Board. Your Bonus, if earned, will be paid
by the later of (i) the fifteenth (15th) day of the third (3rd) month following
the close of the Company’s fiscal year in which the bonus is earned or
(ii) March 15 following the calendar year in which the Bonus is earned.

In addition, subject to the execution and delivery of this letter by you and by
the Company, the Company will recommend that the Board grant you (i) an option
award to purchase 175,000 shares of the Company’s Common Stock (the “Option
Award”) and (ii) a restricted stock unit award for 145,000 shares of the
Company’s Common Stock (the “RSU Award”). The recommended Option Award would
vest and become exercisable as to 25% of the shares subject thereto on the one
(1) year anniversary of the Start Date and as to an additional 1/48 of the
shares subject thereto on each monthly anniversary thereafter, subject to your
continuing to be a service provider of the Company through the applicable
vesting dates. The recommended RSU Award would vest as to 47,500 of the shares
subject thereto on the first anniversary of the Start Date, and 32,500 of the
shares on each subsequent anniversary of the Start Date, such that 100% of the
shares will have vested on the fourth anniversary of the Start Date, subject to
your continuing to be a service provider of the Company through the applicable
vesting dates. The Option Award and RSU Award would each be subject to the terms
and conditions of the Company’s 2014 Equity Incentive Plan and an award
agreement thereunder. The Option Award would have an exercise price per share
equal to the fair market value per share of the Company’s Common Stock on the
date of the grant of such award, as such fair

 

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market value is determined in accordance with the 2014 Equity Incentive Plan.
The RSU Award agreement would provide that a sufficient number of shares would
be automatically sold from such RSU Award, in an arrangement intended to be
compliance with Rule 10b5-1 under the Securities Exchange Act of 1934 (the
“Exchange Act”), at each vest date to cover the Company’s required withholding
obligations with respect to the vesting of the RSU Award on such date, and the
proceeds of such sale would be provided to the Company for purposes of such
withholding.

Should you accept the Company’s offer of employment, the Company will pay you a
signing bonus of $500,000 less applicable withholding taxes, on the first
payroll date after your Start Date. You will be obliged to pay back to the
Company (i) 100% of the amount of the signing bonus if you resign from your
employment with the Company without Good Reason on or before the first
anniversary of your Start Date, or (ii) 50% of the signing bonus if you resign
from your employment with the Company without Good Reason at any time between
the first anniversary of your Start Date and the second anniversary of your
Start Date.

You will be expected to base your employment with the Company in Seattle,
Washington. To assist in your relocation, the Company will reimburse you for
reasonable expenses you incur to make this transition, including but not limited
to moving expenses, travel expenses, and temporary accommodation expenses
related to you and your immediate family relocating to Seattle, maintaining your
existing house for a period of one (1) year during the course of your
relocation, and with your commute to Seattle prior to such relocation
(collectively, “Relocation Expenses”), up to a maximum aggregate reimbursement
of $100,000. Relocation Expenses must be substantiated in writing (by valid
receipts or any other reasonable method of invoicing, showing proof of payment
for an eligible relocation or commuting cost), which evidence must be submitted
to the Company (or, if instructed by the Company, the Company’s third party
relocation vendor) within thirty (30) days any such Relocation Expense is
incurred. The Relocation Expenses will only be reimbursed to you if you are an
employee of the Company on the date of reimbursement or payment by the Company.
The Company will also gross up your income for the amount (if any) required to
be withheld by the Company for federal income taxes with respect to reimbursed
Relocation Expenses. The Company will not gross up your income for any state
income taxes for which you might have obligations prior to your move to the
State of Washington, and you will be responsible for making any required income
tax payments to such state directly. You will be obliged to pay back to the
Company (i) 100% of the reimbursed Relocation Expenses and associated gross up
if you resign from your employment with the Company without Good Reason on or
before the first anniversary of your Start Date, or (ii) 50% of the reimbursed
Relocation Expenses and associated gross up if you resign from your employment
with the Company without Good Reason at any time between the first and second
anniversaries of your Start Date.

The Company will also reimburse you for up to $5,000 in documented legal
expenses incurred by you in connection with obtaining legal advice related to
your potential employment with the Company, which amount would be payable to you
at the end of the first payroll period following your Start Date.

During your employment, you shall be authorized to incur reasonable documented
expenses in the performance of your duties. The Company shall reimburse you for
all such expenses promptly after the presentation by you of itemized
documentation reflecting such expenditures, all in accordance with the Company’s
procedures and policies as adopted and in effect from time to time.

You should be aware that your employment with the Company will be for no
specified period and will constitute at-will employment. As a result, you are
free to resign at any time, for any reason or for no reason. Similarly, the
Company is free to conclude its employment relationship with you at any time,
with or

 

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without cause, and with or without notice. We request that, in the event of
resignation, you give the Company at least two (2) weeks’ notice. The date you
cease providing services for the Company shall be the “Termination Date,”
provided, however, that, in the event you provide the Company with notice of
resignation, the Termination Date shall be the effective date set forth in such
notice, unless the you and the Company agree otherwise in writing.

If the Company terminates your employment other than for Cause, death or
Disability, or if you terminate your employment for Good Reason, then you will
be entitled to receive, subject to your executing and delivering to the Company,
after such termination of employment, a written general release and, if desired
by the Company, a consulting agreement that requires you to provide reasonable
transition services for a period of up to nine (9) months, provided that such
agreement shall not expect or require you to perform services that would
preclude the termination of your employment from being a “separation from
service” from the Company within the meaning of Section 409A of the Internal
Revenue Code of 1986, as amended (the “Code”) and shall provide for payment of
your reasonable out-of-pocket expenses incurred in providing the transition
service, each in forms reasonably satisfactory to the Company (collectively,
the “Release”), that become effective and irrevocable by the sixtieth (60th) day
following your termination of employment (the “Release Deadline Date”),
(i) continuing payments of severance pay (less applicable withholding taxes) for
a period of twelve (12) months to be paid periodically in accordance with the
Company’s normal payroll policies at a rate equal to the sum of your monthly
base salary rate, in each case as in effect immediately prior to your
termination (but without taking into, account any reduction of your base salary
in breach of this letter), (ii) a pro-rata Bonus, which shall be calculated by
multiplying the percentage of the Bonus year that has elapsed through the
Termination Date by the greater of (A) your Target; or (B) your progress toward
meeting the performance criteria applicable to the current Bonus year pro rated
based on the fraction of the year elapsed through the Termination Date, provided
that if such termination occurs between the beginning of a calendar year and the
date on which a Bonus earned during the prior year has been paid, you will not
forfeit any Bonus you have earned during that prior year but will be paid the
prior year’s Bonus in an amount determined by the Board pursuant to the
Company’s ordinary operation of its annual incentive program, and (iii) if you
elect continuation coverage pursuant to the Consolidated Omnibus Budget
Reconciliation Act of 1985, as amended (“COBRA”) for you and your eligible
dependents within the time period prescribed pursuant to COBRA, the Company will
reimburse you for the COBRA premiums for such coverage (at the coverage levels
in effect immediately prior to your termination) pursuant to the Company’s
normal expense reimbursement policy until the earlier of (A) a period of nine
(9) months from the last date of employment of you with the Company, or (B) the
date upon which you and/or your eligible dependents become covered under similar
plans; provided, however, if the Company determines in its sole discretion that
it cannot provide the COBRA benefits without potentially violating applicable
law (including, without limitation, Section 2716 of the 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 date of your
termination of employment (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. In addition, if at any time
before the first anniversary of your Start Date your employment by the Company
terminates for any reason other than your resignation from your employment with
the Company without Good Reason, then the vesting of 47,500 shares of the RSU
Award will accelerate so that those shares would vest on the Termination Date
rather than on the first anniversary of the Start Date.

 

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Notwithstanding anything to the contrary under this letter, if at any time the
Company determines in its sole discretion that it cannot provide the payments
contemplated by the preceding sentence without violating applicable law
(including, without limitation, Section 2716 of the Public Health Service Act),
you will not receive such payment or any further reimbursements for COBRA
premiums. Notwithstanding the foregoing, if the Release does not become
effective and irrevocable by the Release Deadline Date, you will forfeit any
right to severance payments or other separation benefits under this letter. In
no event will severance payments or other separation benefits be paid or
provided until the Release actually becomes effective and irrevocable. Except as
required by the following paragraph, if the Release becomes effective by the
Release Deadline Date, severance payments and other separation benefits under
this letter will commence on the Release Deadline Date. Except as required by
the following paragraph, any installment payments that would have been made to
you during the period from the date of your termination of employment through
the date the Release becomes effective and irrevocable but for the preceding
sentence will be paid to you on the Release Deadline Date, and the remaining
payments will be made as provided in this letter.

Notwithstanding anything to the contrary in this letter, any severance payments
or benefits under this letter that would be considered deferred compensation
(the “Deferred Payments”) under Section 409A of the Internal Revenue Code (as it
has been and may be amended from time to time) (the “Code”) and any regulations
and guidance that has been promulgated or may be promulgated from time to time
thereunder (“Section 409A”) will not be paid until you have experienced a
“separation from service” within the meaning of Section 409A. Additionally, if
you are a “specified employee” within the meaning of Section 409A at the time of
your separation from service, then the Deferred Payments that would otherwise be
due to you on or within the six (6) month period following your separation from
service but for this paragraph, will accrue during such six (6) month period and
will become payable in a lump sum payment on the date six (6) months and one
(1) day following the date of your termination (such rule, the “Six Month Delay
Rule”). All subsequent Deferred Payments following the application of the Six
Month Delay Rule, if any, will be payable in accordance with the payment
schedule applicable to each payment. It is the intent of this letter to comply
with the requirements of Section 409A so that none of the severance payments
will be subject to the additional tax imposed under Section 409A, and any
ambiguities or ambiguous terms herein will be interpreted to so comply. Each
payment and benefit payable under this letter is intended to constitute a
separate payment for purposes of Section 1.409A-2(b)(2) of the Treasury
Regulations.

If your employment hereunder is terminated, you are not required to seek other
employment or to attempt in any way to reduce any amounts payable to you by the
Company. Further, the amount of any payment or benefit provided for hereunder
shall not be reduced by any compensation earned by you as a result of your
employment by another employer, by retirement benefits, or otherwise.

For purposes of this letter, “Cause” means (i) a willful act of dishonesty made
by you in connection with your responsibilities as an employee, (ii) your
conviction of, or plea of nolo contendere to, a felony or any crime involving
fraud, embezzlement or any other act of moral turpitude, or a material violation
of federal or state law by you that the Board reasonably determines has had or
will have a material detrimental effect on the Company’s reputation or business;
(iii) your gross misconduct (as defined under the Revised Code of Washington
50.04.294(4)); (iv) your willful and material unauthorized use or disclosure of
any proprietary information or trade secrets of the Company or any other party
to whom you owe an obligation of nondisclosure as a result of your relationship
with the Company; (v) your willful breach of any material obligations under any
written agreement or covenant with the Company; or (vi) your continued
substantial failure to perform your employment duties (other than as a result of
your physical or mental incapacity) after you have received a written demand of
performance from the Board that specifically sets forth the factual basis for
the Board’s determination that you have not substantially performed your duties
and have failed to cure such non-performance to the Board’s reasonable
satisfaction within thirty (30) business days after

 

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receiving such notice. For purposes of this paragraph, no act or failure to act
shall be considered willful unless it is done in bad faith and without
reasonable intent that the act or failure to act was in the best interest of the
Company or required by law. Any act, or failure to act, based upon authority or
instructions given to you pursuant to a resolution duly adopted by the Board or
based on the advice of counsel for the Company will be conclusively presumed to
be done or omitted to be done by you in good faith and in the best interest of
the Company.

For purposes of this letter, “Disability” means: (i) an inability to engage in
any substantial gainful activity by reason of any medically determinable
physical or mental impairment which can be expected to result in death or can be
expected to last for a continuous period of not less than twelve (12) months; or
(ii) receipt of income replacement benefits for a period of not less than three
(3) months, by reason of any medically determinable physical or mental
impairment which can be expected to last for a continuous period of not less
than twelve (12) months, under an accident and health plan covering employees of
the Company.

For purposes of this letter, “Good Reason” means your resignation within thirty
(30) days following expiration of any Company cure period (discussed below)
following the occurrence of one or more of the following, without your written
consent: (i) a material reduction in your base salary (in which case, severance
for a resignation shall be based upon your base salary prior to the reduction);
(ii) a material diminution of your duties, responsibilities or reporting lines;
(iii) a change in the location of your employment of more than fifty (50) miles;
or (iv) the Company’s material breach of the terms of this letter (which shall
include the failure of the Board to substantially grant the Option Award and/or
RSU Award described on pages 1 and 2 of this letter) or any other material
written agreement or covenant with you related to your provision of services to
the Company. You will not resign for Good Reason without first providing the
Company with written notice of the acts or omissions constituting the grounds
for Good Reason within ninety (90) days of the initial existence of the grounds
for Good Reason and a reasonable cure period of not less than thirty (30) days
following the date of such notice (during which the grounds have not been
cured).

You acknowledge and agree that you will disclose to the Company any and all
agreements that may affect your eligibility to be employed by the Company or
limit the manner in which you may be employed. It is the Company’s understanding
that any such agreements will not prevent you from performing the duties of your
position and you represent that such is the case. Please notify the Company
immediately if this is not the case. Similarly, you agree not to bring any third
party confidential information to the Company, including that of any former
employer, and that in performing your duties for the Company you will not in any
way utilize any such information.

You agree that, during the term of your employment with the Company, you will
not, without the prior written consent of the Company, engage in any other
employment, occupation, consulting or other business activity directly related
to the business in which the Company is now involved or becomes involved during
the term of your employment. Notwithstanding the foregoing sentence, the Company
understands that during the period between the Start Date and December 31, 2015,
you will be involved in closing your research lab at Johns Hopkins University
School of Medicine and assisting associated students, post-doctoral fellows and
technicians to conclude or transition research and agrees that you may complete
this outside work so long as it does not materially interfere with the
performance of your obligations to the Company. The Company agrees that any
intellectual property in the field of cancer immunology that is produced by
research activities of this lab performed during or prior to this transition
period are not Company Inventions (as defined in the At-Will Employment
Agreement attached as Exhibit A hereto) and that you may amend the List of Prior
Inventions and Original Works of Authorship up to and including January 31, 2016
to include such intellectual property as Prior Inventions.

 

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As a Company employee, you will be expected to abide by the Company’s rules and
standards. Specifically, you will be required to sign an acknowledgment that you
have read and that you understand the Company’s rules of conduct and other
policies which are included or referenced in “The People Pact” (the Company’s
employee handbook), which the Company will provide to you. To the extent that
policies set forth in The People Pact conflict with those set forth in this
offer letter, the offer letter shall control.

You are also required to sign and comply with an At Will Employee Agreement, in
the form attached as Exhibit A hereto, which requires, among other provisions,
the assignment of patent rights to any invention made during your employment at
the Company, and non-disclosure of Company proprietary information. To the
extent that provisions set forth in the At Will Employee Agreement conflict with
those set forth in this offer letter, the offer letter shall control.

In the event of any dispute or claim relating to or arising out of our
employment relationship, you and the Company agree that (i) any and all disputes
between you and the Company shall be fully and finally resolved by binding
arbitration, (ii) both you and the Company are waiving and hereby waive any and
all rights to a jury trial but all court remedies will be available in
arbitration, (iii) all disputes shall be resolved by a neutral arbitrator
acceptable to you and the Company who shall issue a written opinion, and
(iv) the Company shall pay all the arbitration fees, except an amount equal to
the filing fees you would have paid had you filed a complaint in a court of law.
Please note that we must receive your signed At Will Employee Agreement by the
Start Date or the terms and provisions of this letter shall terminate.

The Company will recommend to the Board that you be deemed an “executive
officer” of the Company within the meaning of Item 401(b) of Regulation S-K
under the Securities Act of 1933 and for purposes of Section 16 under the
Exchange Act. In such event, you will become subject to Section 16 of the
Exchange Act, including reporting requirements for transactions in the Company’s
equity securities. In order to enable the Company to assist you with fulfilling
such reporting requirements, you will be asked to sign and deliver the
Section 16 power of attorney attached hereto as Exhibit B. The Company will also
offer you the opportunity to enter into an indemnification agreement with the
Company for your benefit, on the Company’s standard form of indemnification
agreement for its directors and officers, as filed with the Securities and
Exchange Commission.

To accept the Company’s terms of employment described herein, please sign and
date this letter in the space provided below and return it to the Company by
May 27, 2015. This letter and the At Will Employee Agreement set forth the terms
of your employment with the Company and supersede any prior representations or
agreements, whether written or oral. This letter may not be modified or amended
except by a written agreement signed by the Chief Executive Officer of the
Company and you.

 

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We look forward to working with you at Juno Therapeutics, Inc.

 

Sincerely,

/s/ Hans Bishop

Hans Bishop

Chief Executive Officer, Juno Therapeutics, Inc.

Agreed to and accepted:

 

Signature:  

/s/ Hyam Levitsky

Printed Name:   Hyam Levitsky Date: May 27, 2015

Enclosures

 

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