13G Filing: Biotechnology Value Fund LP and Syndax Pharmaceuticals Inc (SNDX)

Item 2(d).

Title of Class of Securities:

Common Stock, $0.0001 par value (the “Common Stock”)

Item 2(e).

CUSIP Number:

87164F105

Item 3.

If This Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:

/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 November
13, 2017 (i) BVF beneficially owned 947,350 shares of Common Stock, (ii) BVF2 beneficially owned 629,906 shares of Common Stock,
and (iii) Trading Fund OS beneficially owned 169,388 shares of Common Stock.

Partners OS, as the general partner
of Trading Fund OS, may be deemed to beneficially own the 169,388 shares of 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
2,021,018 shares of Common Stock beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, and certain Partners managed
accounts (the “Partners Managed Accounts”), including 274,374 shares of Common Stock held in the Partners Managed Accounts.