| Explanation of Responses: |
| (1) | Vivo Ventures VII, LLC is the general partner of each of Vivo Ventures Fund VII, L.P. and Vivo Ventures VII Affiliates Fund, L.P. ("Vivo Fund VII"), the record holder of the securities. Frank Kung, Albert Cha, Edgar Engleman, Chen Yu and Shan Fu are managing members of Vivo Ventures VII, LLC and may be deemed to share voting and dispositive power over the securities held by Vivo Fund VII. Each of these individuals disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. |
| (2) | Vivo Opportunity, LLC is the general partner of Vivo Opportunity Fund, L.P., the record holder of the securities. Albert Cha, Gaurav Aggarwal, Shan Fu, Frank Kung and Michael Chang are managing members of Vivo Opportunity, LLC and may be deemed to share voting and dispositive power over the securities held by Vivo Opportunity Fund, L.P. Each of these individuals disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. |
| (3) | Vivo Capital IX, LLC is the general partner of Vivo Capital Fund IX, L.P., the record holder of the securities. Frank Kung, Albert Cha, Shan Fu, Edgar Engleman and Chen Yu are managing members of Vivo Capital IX, LLC and may be deemed to share voting and dispositive power over the securities held by Vivo Capital Fund IX, L.P. Each of these individuals disclaims beneficial ownership over such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes. |
| (4) | Each share of Series A Convertible Voting Preferred Stock (the "Series A Preferred Stock") will convert into 3,030 shares of the Issuer's Common Stock (a) at the option of the holder and (b) automatically upon the 5th trading date following the Issuer's announcement of receiving stockholder approval for the first reverse stock split of the Issuer following November 13, 2019, provided that, the Issuer will not effect any conversion, and the holder will not have the right to convert, subject to certain exceptions, the Series A Preferred Stock for shares of Common Stock if, as a result of such conversion, the holder, together with its affiliates and other attribution parties, would own more than 9.99% of the total number of shares of Common Stock then issued and outstanding, which percentage may be changed at the holder's election to a lower percentage at any time or to a higher percentage upon 61 days' notice to the Issuer, |
| (5) | (continued from footnote 4) and provided further that such limitation on exercise will automatically increase to 19.99% of the total number of shares of Common Stock then issued and outstanding during the period that any employee, manager, partner, managing director or affiliate of such holder is then serving on the Issuer's board of directors. As Gaurav Aggarwal, managing member of Vivo Opportunity, LLC, which is the general partner of Vivo Opportunity Fund, L.P. is a member of the Issuer's board of directors, the conversion limitation for Series A Preferred Stock held by the Reporting Persons is 19.99%. The Series A Preferred Stock has no expiration date. |
| (6) | Each Series A Warrant will be exercisable for one share of Common Stock. The Series A Warrants are exercisable on the first trading day following the date the Issuer obtains stockholder approval of an amendment to its certificate of incorporation increasing the aggregate number of authorized shares of its Common Stock, such that the Issuer shall have sufficient authorized but unissued shares of Common Stock, solely for the purpose of enabling the Issuer to issue shares of its Common Stock upon exercise of the Series A Warrants and the Series B Warrants (the "Warrant Exercise Date"), provided that, at each holder's election, the holder will be prohibited, subject to certain exceptions, from exercising the Series A Warrant for shares of Common Stock if, |
| (7) | (continued from footnote 6) as a result of such exercise, the holder, together with its affiliates and other attribution parties, would own more than 9.99% of the total number of shares of Common Stock then issued and outstanding, which percentage may be changed at the holder's election to a lower percentage at any time or to a higher percentage upon 61 days' notice to the Issuer. Each Series A Warrant will expire five years from the date it first becomes exercisable. |
| (8) | Each Series B Warrant will be exercisable for 0.33 shares of Common Stock. The Series B Warrants are exercisable on the Warrant Exercise Date, provided that, at each holder's election, the holder will be prohibited, subject to certain exceptions, from exercising the Series B Warrant for shares of Common Stock if, as a result of such exercise, the holder, together with its affiliates and other attribution parties, would own more than 9.99% of the total number of shares of Common Stock then issued and outstanding, which percentage may be changed at the holder's election to a lower percentage at any time or to a higher percentage upon 61 days' notice to the Issuer. Each Series B warrant will expire on the 75th day anniversary of the Issuer's announcement of top-line data from MOMENTUM, its planned Phase 3 clinical trial of momelotinib for patients with myelofibrosis. |