	/x/	Not applicable.

(a)	/ /	Broker or dealer registered under Section 15 of the Exchange Act.

(b)	/ /	Bank as defined in Section 3(a)(6) of the Exchange Act.

(c)	/ /	Insurance company as defined in Section 3(a)(19) of the Exchange Act.

(d)	/ /	Investment company registered under Section 8 of the Investment Company Act.

(e)	/ /	An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E).

(f)	/ /	An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F).

(g)	/ /	A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G).

(h)	/ /	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act.

(i)	/ /	A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act.

(j)	/ /	Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

(k)	/ /	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J), please specify the type of institution: ____

Item 4.

Ownership

(a)

Amount beneficially owned:

As of the close of business on June
29, 2017 (i) BVF beneficially owned 941,783 Common Stock, (ii) BVF2 beneficially owned 608,749 Common Stock, and (iii) Trading
Fund OS beneficially owned 171,334 Common Stock.

Partners OS as the general partner
of Trading Fund OS may be deemed to beneficially own the 171,334 Common Stock beneficially owned by Trading Fund OS.

Partners, as the general partner of
BVF, BVF2, the investment manager of Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the
2,026,998 Common Stock beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, and a certain Partners managed accounts
(the “Partners Managed Accounts”), including 305,132 Common Stock held in the Partners Managed Accounts.

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