Exercise of Option. Effective as of today, the undersigned ("Optionee") hereby elects to exercise Optionee's option to purchase ​ shares of the Common Stock (the "Shares") of Assembly Biosciences, Inc. (the "Company") under and pursuant to the Company's Amended and Restated 2014 Stock Incentive Plan, as amended (the "Plan") and the Notice of Stock Option Grant dated ​, 20​ with its attached Stock Option Agreement (the "Option Agreement"). The purchase price for the Shares shall be ​ as required by the Option Agreement. Optionee herewith delivers to the Company the full Exercise Price for the Shares.

The Option shall not be exercisable as of the Grant Date set forth in the Grant Notice. After the Grant Date, to the extent not previously exercised, and subject to termination or acceleration as provided in these Standard Terms and Conditions and the Plan, the Option shall be exercisable only to the extent it becomes vested, as described in the Grant Notice, these Standard Terms and Conditions and/or the terms of the Plan, to purchase up to that number of shares of Common Stock as set forth in the Grant Notice, provided that (except as may be provided otherwise in Section 4 below) the Participant remains employed with the Company and does not experience a termination of employment.

Option Exercise Price. The exercise price per Share subject to each Option shall be set by the Administrator, but shall not be less than one hundred percent (100%) of the Fair Market Value of a Share on the date the Option is granted (or, as to Incentive Stock Options, on the date the Option is modified, extended or renewed for purposes of Section 424(h) of the Code). In addition, in the case of Incentive Stock Options granted to a Greater Than 10% Stockholder, such price shall not be less than one hundred ten percent (110%) of the Fair Market Value of a Share on the date the Option is granted (or the date the Option is modified, extended or renewed for purposes of Section 424(h) of the Code).

Exercise of Option. Options may be exercised by delivery to the Company of a written notice of exercise signed by the proper person or by any other form of notice (including electronic notice) approved by the Board together with payment in full as specified in Section 5(f) for the number of shares for which the Option is exercised. Shares of Common Stock subject to the Option will be delivered by the Company as soon as practicable following exercise.

Exercise of Option. Each of the Second Lien Secured Parties shall have the option at any time within thirty (30) days of a Triggering Event (the “Purchase Option Period”) to purchase all (but not less than all) of the First Lien Debt from the First Lien Secured Parties. The Second Lien Secured Parties electing to purchase (the “Purchasing Parties”) shall give at least five (5) Business Days written notice to First Lien Agent of their election to exercise such purchase option (the “Purchase Option Notice”). A Purchase Option Notice from such Purchasing Parties to First Lien Agent shall be irrevocable.

Exercise of Option. I hereby elect to exercise the Option to purchase the following number of Shares, all of with are Vested Shares in accordance with the Notice and/or Option Agreement:

Exercise of Option. This Option shall be exercisable during its term in accordance with the Vesting/Exercise Schedule set out in the Notice and with the provisions of Section 9 of the Plan as follows:

Exercise of Option. Subject to the terms and conditions hereof, Purchaser hereby elects to exercise his or her option to purchase shares of the Common Stock (the “Shares”) of the Company under and pursuant to the Plan and the Stock Option Agreement dated (the “Option Agreement”). The purchase price for the Shares shall be $ per Share for a total purchase price of $ . The term “Shares” refers to the purchased Shares and all securities received in replacement of the Shares or as stock dividends or splits, all securities received in replacement of the Shares in a recapitalization, merger, reorganization, exchange or the like, and all new, substituted or additional securities or other properties to which Purchaser is entitled by reason of Purchaser’s ownership of the Shares.

No Obligation to Exercise Option. The grant and acceptance of this option imposes no obligation on the Employee to exercise it.

The Option Period for an Option will be determined by the Committee at the time the Option is granted and may be up to 10 years from the date the Option is granted. At the time an Option is granted, the Committee may determine that, with respect to that Option, upon the occurrence of one of the events described in [subsection 10.1] there will come into force a time limit for exercise of such Option which is different than the Option Period, and in the event of such a determination, the Option Agreement for such Option will contain provisions which specify the events and time limits related to that determination. Subject to the applicable maximum Option Period provided for in this [subsection 8.1] and subject to applicable regulatory requirements and approvals, the Committee may extend the Option Period of an outstanding Option beyond its original expiration date, provided that shareholder approval, including disinterested shareholder approval if required by the TSX, is obtained for any extension of the Option Period of an outstanding Option.