Exhibit 10.15

Editas Medicine, Inc.

Inducement Stock Option Agreement

1.             Grant of Option.

This agreement evidences the grant by Editas Medicine, Inc., a Delaware
corporation (the “Company”), on [___________] (the “Grant Date”) to
[___________] (the “Participant”), of an option to purchase, in whole or in
part, on the terms provided herein, a total of [___________] shares (the
“Shares”) of common stock, $0.0001 par value per share, of the Company (“Common
Stock”) at $[_____] per Share.  Unless earlier terminated, this option shall
expire at 5:00 p.m., Eastern time, on [___________] (the “Final Exercise Date”).

The option evidenced by this agreement was granted to the Participant pursuant
to the inducement grant exception under Nasdaq Stock Market Rule 5635(c)(4), and
not pursuant to the Company’s 2015 Stock Incentive Plan (the “Plan”) or any
equity incentive plan of the Company, as an inducement that is material to the
Participant’s employment with the Company.

It is intended that the option evidenced by this agreement shall not be an
incentive stock option as defined in Section 422 of the Internal Revenue Code of
1986, as amended, and any regulations promulgated thereunder (the “Code”). 
Except as otherwise indicated by the context, the term “Participant”, as used in
this option, shall be deemed to include any person who acquires the right to
exercise this option validly under its terms.

2.             Vesting Schedule.

Except as otherwise provided herein, this option will become exercisable
(“vest”) as to 25% of the original number of Shares on one-year anniversary of
the Grant Date and as to an additional 2.0833% of the original number of Shares
at the end of each successive month following the one-year anniversary of the
Grant Date until the fourth anniversary of the Grant Date.

The right of exercise shall be cumulative so that to the extent the option is
not exercised in any period to the maximum extent permissible it shall continue
to be exercisable, in whole or in part, with respect to all Shares for which it
is vested until the earlier of the Final Exercise Date or the termination of
this option under Section 3 hereof.

3.             Exercise of Option.

(a)           Form of Exercise.  Each election to exercise this option shall be
in writing, signed by the Participant (or such electronic notice as is approved
by the Company), and received by the Company at its principal office,
accompanied by this agreement and payment in full as follows:

(1)           in cash or by check, payable to the order of the Company;

(2)           by (i) delivery of an irrevocable and unconditional undertaking by
a creditworthy broker to deliver promptly to the Company sufficient funds to pay
the exercise price and any required tax withholding or (ii) delivery by the
Participant to the Company of a copy of irrevocable and unconditional
instructions to a creditworthy broker to deliver promptly to the Company cash or
a check sufficient to pay the exercise price and any required tax withholding;

(3)           to the extent approved by the Board of Directors of the Company
(the “Board”), in its sole discretion, by delivery (either by actual delivery or
attestation) of shares of Common Stock owned by the Participant valued at their
fair market value per share as determined by (or in a manner approved by) the
Board (the “Fair Market Value”), provided (i) such method of payment is then
permitted under applicable law, (ii) such Common Stock, if acquired directly
from the Company, was owned by the Participant for such minimum period of time,
if any, as may be established by the Board in its discretion and (iii) such
Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting
or other similar requirements;

(4)           to the extent approved by the Board, in its sole discretion, by
delivery of a notice of “net exercise” to the Company, as a result of which the
Participant would receive (i) the number of shares underlying the portion of
this being exercised, less (ii) such number of shares as is equal to (A) the
aggregate exercise price for the portion of this option being exercised divided
by (B) the Fair Market Value on the date of exercise;

(5)           to the extent permitted by applicable law or approved by the
Board, in its sole discretion, by payment of such other lawful consideration as
the Board may determine; or

(6)           by any combination of the above permitted forms of payment.

The Participant may purchase less than the number of shares covered hereby,
provided that no partial exercise of this option may be for any fractional share
or for fewer than ten whole shares.

(b)           Continuous Relationship with the Company Required.  Except as
otherwise provided in this Section 3, this option may not be exercised unless
the Participant, at the time he or she exercises this option, is, and has been
at all times since the Grant Date, an employee, officer or a director of, or
consultant or advisor to, the Company or any other entity the employees,
officers, directors, consultants, or advisors of which are eligible to receive
option grants under the Plan (an “Eligible Participant”).

(c)           Termination of Relationship with the Company.  If the Participant
ceases to be an Eligible Participant for any reason, then, except as provided in
paragraphs (d) and (e) below, the right to exercise this option shall terminate
three months after such cessation (but in no event after the Final Exercise
Date), provided that this option shall be exercisable only to the extent that
the Participant was entitled to exercise this option on the date of such
cessation.  Notwithstanding the foregoing, if the Participant, prior to the
Final Exercise Date, violates the restrictive covenants (including, without
limitation, the non-competition, non-solicitation, or

confidentiality provisions of any employment contract, confidentiality and
nondisclosure agreement or other agreement between the Participant and the
Company, the right to exercise this option shall terminate immediately upon such
violation.

(d)           Exercise Period Upon Death or Disability.  If the Participant dies
or becomes disabled (within the meaning of Section 22(e)(3) of the Code) prior
to the Final Exercise Date while he or she is an Eligible Participant and the
Company has not terminated such relationship for “cause” as specified in
paragraph (e) below, this option shall be exercisable, within the period of one
year following the date of death or disability of the Participant, by the
Participant (or in the case of death by an authorized transferee), provided that
this option shall be exercisable only to the extent that this option was
exercisable by the Participant on the date of his or her death or disability,
and further provided that this option shall not be exercisable after the Final
Exercise Date.

(e)           Termination for Cause.  If, prior to the Final Exercise Date, the
Participant’s employment or other relationship with the Company is terminated by
the Company for Cause (as defined below), the right to exercise this option
shall terminate immediately upon the effective date of such termination of
employment or other relationship. If, prior to the Final Exercise Date, the
Participant is given notice by the Company of the termination of his or her
employment or other relationship by the Company for Cause, and the effective
date of such termination is subsequent to the date of delivery of such notice,
the right to exercise this option shall be suspended from the time of the
delivery of such notice until the earlier of (i) such time as it is determined
or otherwise agreed that the Participant’s employment or other relationship
shall not be terminated for Cause as provided in such notice or (ii) the
effective date of such termination (in which case the right to exercise this
option shall, pursuant to the preceding sentence, terminate upon the effective
date of such termination). If the Participant is party to an employment,
consulting or severance agreement or plan with the Company that contains a
definition of “cause” for termination of employment or other relationship,
“Cause” shall have the meaning ascribed to such term in such agreement.
Otherwise, “Cause” shall mean willful misconduct by the Participant or willful
failure by the Participant to perform his or her responsibilities to the Company
(including, without limitation, breach by the Participant of any provision of
any employment, consulting, advisory, nondisclosure, non-competition or other
similar agreement between the Participant and the Company), as determined by the
Company, which determination shall be conclusive. The Participant’s employment
or other relationship shall be considered to have been terminated for “Cause” if
the Company determines, within 30 days after the Participant’s resignation, that
termination for Cause was warranted.

4.             Agreement in Connection with Public Offering.

The Participant agrees, in connection with an underwritten public offering of
the Common Stock pursuant to a registration statement under the Securities Act,
(i) not to (a) offer, pledge, announce the intention to sell, sell, contract to
sell, sell any option or contract to purchase, purchase any option or contract
to sell, grant any option, right or warrant to purchase, or otherwise transfer
or dispose of, directly or indirectly, any shares of Common Stock or any other
securities of the Company or (b) enter into any swap or other agreement that
transfers, in

whole or in part, any of the economic consequences of ownership of shares of
Common Stock or other securities of the Company, whether any transaction
described in clause (a) or (b) is to be settled by delivery of securities, in
cash or otherwise, during the period beginning on the date of the filing of such
registration statement with the Securities and Exchange Commission and ending up
to 90 days after the date of the final prospectus relating to the offering, and
(ii) to execute any agreement reflecting clause (i) above as may be requested by
the Company or the managing underwriters at the time of such offering.  The
Company may impose stop-transfer instructions with respect to the shares of
Common Stock or other securities subject to the foregoing restriction until the
end of the “lock-up” period.

5.             Withholding.

No Shares will be issued pursuant to the exercise of this option unless and
until the Participant pays to the Company, or makes provision satisfactory to
the Company for payment of, any federal, state or local withholding taxes
required by law to be withheld in respect of this option.  The Participant must
satisfy all applicable federal, state, and local or other income and employment
tax withholding obligations before the Company will deliver stock certificates
or otherwise recognize ownership of Common Stock under this option.  The Company
may decide to satisfy the withholding obligations through additional withholding
on salary or wages.  If the Company elects not to or cannot withhold from other
compensation, the Participant must pay the Company the full amount, if any,
required for withholding or have a broker tender to the Company cash equal to
the withholding obligations. Payment of withholding obligations is due before
the Company will issue any shares on exercise of this option or at the same time
as payment of the exercise price, unless the Company determines otherwise. If
approved by the Board, in its sole discretion, a Participant may satisfy such
tax obligations in whole or in part by delivery (either by actual delivery or
attestation) of shares of Common Stock underlying this option valued at their
Fair Market Value; provided, however, except as otherwise provided by the Board,
that the total tax withholding where stock is being used to satisfy such tax
obligations cannot exceed the Company’s minimum statutory withholding
obligations (based on minimum statutory withholding rates for federal and state
tax purposes, including payroll taxes, that are applicable to such supplemental
taxable income), except that, to the extent that the Company is able to retain
shares of Common Stock having a fair market value (determined by (or in a manner
approved by) the Company)  that exceeds the statutory minimum applicable
withholding tax without financial accounting implications or the Company is
withholding in a jurisdiction that does not have a statutory minimum withholding
tax, the Company may retain such number of shares of Common Stock (up to the
number of shares having a fair market value equal to the maximum individual
statutory rate of tax (determined by (or in a manner approved by) the Company))
as the Company shall determine in its sole discretion to satisfy the tax
liability associated with any Award.  Shares used to satisfy tax withholding
requirements cannot be subject to any forfeiture, unfulfilled vesting or other
similar requirements.

6.             Transfer Restrictions; Clawback.

This option may not be sold, assigned, transferred, pledged or otherwise
encumbered by the Participant, either voluntarily or by operation of law, except
by will or the laws of descent

and distribution, and, during the lifetime of the Participant, this option shall
be exercisable only by the Participant. In accepting this option, the
Participant agrees to be bound by any clawback policy that the Company has
adopted or may adopt in the future.

7.             Adjustments for Changes in Common Stock and Certain Other Events.

(a)           Changes in Capitalization.  In the event of any stock split,
reverse stock split, stock dividend, recapitalization, combination of shares,
reclassification of shares, spin-off or other similar change in capitalization
or event, or any dividend or distribution to holders of Common Stock other than
an ordinary cash dividend, the number and class of securities and exercise price
per share of this option shall be equitably adjusted by the Company in the
manner determined by the Board.  Without limiting the generality of the
foregoing, in the event the Company effects a split of the Common Stock by means
of a stock dividend and the exercise price of and the number of shares subject
to this option are adjusted as of the date of the distribution of the dividend
(rather than as of the record date for such dividend), then the Participant, if
he or she exercises this option between the record date and the distribution
date for such stock dividend, shall be entitled to receive, on the distribution
date, the stock dividend with respect to the shares of Common Stock acquired
upon exercise of this option, notwithstanding the fact that such shares were not
outstanding as of the close of business on the record date for such stock
dividend.

(b)           Reorganization Events.  A “Reorganization Event” shall mean: 
(a) any merger or consolidation of the Company with or into another entity as a
result of which all of the Common Stock of the Company is converted into or
exchanged for the right to receive cash, securities or other property or is
cancelled, (b) any transfer or disposition of all of the Common Stock of the
Company for cash, securities or other property pursuant to a share exchange or
other transaction or (c) any liquidation or dissolution of the Company.  In
connection with a Reorganization Event, the Board may take any one or more of
the following actions with respect to this option (or any portion thereof) on
such terms as the Board determines: (i) provide that this option shall be
assumed, or substantially equivalent option shall be substituted, by the
acquiring or succeeding corporation (or an affiliate thereof), (ii) upon written
notice to the Participant, provide that the unvested and/ or unexercised portion
of this option will terminate immediately prior to the consummation of such
Reorganization Event unless exercised by the Participant within a specified
period following the date of such notice, (iii) provide that this option shall
become exercisable, realizable, or deliverable, or restrictions applicable to
this option shall lapse, in whole or in part prior to or upon such
Reorganization Event, (iv) in the event of a Reorganization Event under the
terms of which holders of Common Stock will receive upon consummation thereof a
cash payment for each share surrendered in the Reorganization Event (the
“Acquisition Price”), make or provide for a cash payment to the Participant with
respect to this option equal to (A) the number of shares of Common Stock subject
to the vested portion of this option (after giving effect to any acceleration of
vesting that occurs upon or immediately prior to such Reorganization Event)
multiplied by (B) the excess, if any, of (I) the Acquisition Price over (II) the
exercise price of this option and any applicable tax withholdings, in exchange
for the termination of this option, (v) provide that, in connection with a
liquidation or dissolution of the Company, this option shall convert into the
right to receive liquidation proceeds (if 

applicable, net of the exercise, measurement or purchase price thereof and any
applicable tax withholdings) and (vi) any combination of the foregoing.

For purposes of clause (i) above, this option shall be considered assumed if,
following consummation of the Reorganization Event, this option confers the
right to purchase, for each share of Common Stock subject to this option
immediately prior to the consummation of the Reorganization Event, the
consideration (whether cash, securities or other property) received as a result
of the Reorganization Event by holders of Common Stock for each share of Common
Stock held immediately prior to the consummation of the Reorganization Event
(and if holders were offered a choice of consideration, the type of
consideration chosen by the holders of a majority of the outstanding shares of
Common Stock); provided, however, that if the consideration received as a result
of the Reorganization Event is not solely common stock of the acquiring or
succeeding corporation (or an affiliate thereof), the Company may, with the
consent of the acquiring or succeeding corporation, provide for the
consideration to be received upon the exercise of this option to consist solely
of such number of shares of common stock of the acquiring or succeeding
corporation (or an affiliate thereof) that the Board determined to be equivalent
in value (as of the date of such determination or another date specified by the
Board) to the per share consideration received by holders of outstanding shares
of Common Stock as a result of the Reorganization Event.

8.             Miscellaneous.

(a)           No Right To Employment or Other Status.  The grant of this option
shall not be construed as giving the Participant the right to continued
employment or any other relationship with the Company.  The Company expressly
reserves the right at any time to dismiss or otherwise terminate its
relationship with the Participant free from any liability or claim hereunder.

(b)           No Rights As Stockholder.  Subject to the provisions of this
option, the  Participant shall not have any rights as a stockholder with respect
to any shares of Common Stock to be distributed with respect to this option
until becoming the record holder of such shares.

(c)           Entire Agreement.  This Agreement and the Company’s Severance
Benefits Plan, to the extent applicable to Participant, constitute the entire
agreement between the parties, and supersede all prior agreements and
understandings, relating to the subject matter hereof.

(d)           Amendment.  The Board may amend, modify or terminate this
Agreement, including but not limited to, substituting another option of the same
or a different type and changing the date of exercise or realization. 
Notwithstanding the foregoing, the Participant’s consent to such action shall be
required unless (i) the Board determines that the action, taking into account
any related action, would not materially and adversely affect the Participant,
or (ii) the change is permitted under Section 7 of this Agreement.

(e)            Acceleration.  The Board may at any time provide that this option
shall become immediately exercisable in whole or in part, free of some or all
restrictions or conditions, or otherwise realizable in whole or in part, as the
case may be.

(f)             Conditions on Delivery of Stock.  The Company will not be
obligated to deliver any shares of Common Stock pursuant to this Agreement until
(i) all conditions of this Agreement have been met to the satisfaction of the
Company, (ii) in the opinion of the Company’s counsel, all other legal matters
in connection with the issuance and delivery of such shares have been satisfied,
including any applicable securities laws and regulations and any applicable
stock exchange or stock market rules and regulations, and (iii) the Participant
has executed and delivered to the Company such representations or agreements as
the Company may consider appropriate to satisfy the requirements of any
applicable laws, rules or regulations.

(g)             Administration by Board.  The Board will administer this
Agreement and may construe and interpret the terms hereof.  The Board may
correct any defect, supply any omission or reconcile any inconsistency in this
Agreement in the manner and to the extent it shall deem expedient to carry the
Agreement into effect and it shall be the sole and final judge of such
expediency.  No director or person acting pursuant to the authority delegated by
the Board shall be liable for any action or determination relating to or under
this Agreement made in good faith.

(h)             Appointment of Committees.  To the extent permitted by
applicable law, the Board may delegate any or all of its powers hereunder to one
or more committees or subcommittees of the Board (a “Committee”).  All
references herein to the “Board” shall mean the Board or a Committee to the
extent that the Board’s powers or authority hereunder have been delegated to
such Committee.

(i)               Severability.  The invalidity or unenforceability of any
provision hereof shall not affect the validity or enforceability of any other
provision hereof, and each such other provision shall be severable and
enforceable to the extent permitted by law.

(j)              Governing Law.  This Agreement shall be governed by and
interpreted in accordance with the laws of the State of Delaware, excluding
choice-of-law principles of the law of such state that would require the
application of the laws of a jurisdiction other than the State of Delaware.

(k)              Counterparts.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original but all of which
together will constitute one in the same instrument.

The Company has caused this option to be executed by its duly authorized
officer.

 

 

EDITAS MEDICINE, INC.

 

 

 

 

 

 

 

By:

 

 

Name:

 

 

Title:

 

 

PARTICIPANT’S ACCEPTANCE

The undersigned hereby accepts the foregoing option and agrees to the terms and
conditions thereof.

 

 

 

 

 

 

 

PARTICIPANT:

 

 

 

 

 

 

 

 

 

 

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Address: