13G Filing: Biotechnology Value Fund LP and CytomX Therapeutics Inc (CTMX)

BVF Inc., as the general partner of
Partners, may be deemed to beneficially own the 2,026,998 Common Stock beneficially owned by Partners.

Mr. Lampert, as a director and officer
of BVF Inc., may be deemed to beneficially own the 2,026,998 Common Stock beneficially owned by BVF Inc.

The foregoing should not be construed
in and of itself as an admission by any Reporting Person as to beneficial ownership of any Common Stock owned by another Reporting
Person. Partners OS disclaims beneficial ownership of the Common Stock beneficially owned by Trading Fund OS. Each of Partners,
BVF Inc. and Mr. Lampert disclaims beneficial ownership of the Common Stock beneficially owned by BVF, BVF2, Trading Fund OS, and
the Partners Managed Accounts, and the filing of this statement shall not be construed as an admission that any such person or
entity is the beneficial owner of any such securities.

(b)

Percent of class:

The following percentages are based
on 36,749,732 shares of Common Stock outstanding, as of April 28, 2017, which is the total number of shares of Common Stock outstanding
as reported in the Issuer’s Definitive Proxy Statement, filed with the Securities and Exchange Commission on May 9, 2017.

As of the close of business on June
29, 2017 (i) BVF beneficially owned approximately 2.6% of the outstanding Common Stock, (ii) BVF2 beneficially owned approximately
1.7% of the outstanding Common Stock, (iii) Trading Fund OS beneficially owned less than 1% of the outstanding Common Stock (iv)
Partners OS may be deemed to beneficially own less than 1% of the outstanding Common Stock, and (v) each of Partners, BVF Inc.
and Mr. Lampert may be deemed to beneficially own approximately 5.5% of the outstanding Common Stock (less than 1% of which is
held in the Partners Managed Accounts).

(c)

Number of shares as to which such person has:

(i)

Sole power to vote or to direct the vote

See Cover Pages Items 5-9.

(ii)

Shared power to vote or to direct the vote

See Cover Pages Items 5-9.

(iii)

Sole power to dispose or to direct the disposition of

See Cover Pages Items 5-9.

(iv)

Shared power to dispose or to direct the disposition of

See Cover Pages Items 5-9.