SEC FORM 3

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

McCarthy Sean A.

(Last)

(First)

(Middle)

343 OYSTER POINT BLVD.

SUITE 100

(Street)

SOUTH SAN FRANCISCO

94080

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/07/2015

3. Issuer Name and Ticker or Trading Symbol
CytomX Therapeutics, Inc. [ CTMX ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	President and CEO

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	158,737	I⁽¹⁾	In Trust⁽¹⁾

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
Employee Stock Option (right to buy)	⁽²⁾	09/20/2021	Common Stock	381,304	$1.1339	D
Employee Stock Option (right to buy)	⁽³⁾	02/25/2023	Common Stock	137,274	$0.945	D
Employee Stock Option (right to buy)	12/31/2013	02/25/2023	Common Stock	48,379	$0.945	D
Employe Stock Option (right to buy)	⁽⁴⁾	02/08/2025	Common Stock	205,320	$1.5749	D
Employee Stock Option (right to buy)	⁽⁵⁾	08/25/2025	Common Stock	438,302	$6.6147	D

Explanation of Responses:

1. Held in McCarthy Family Trust dated August 9, 2001, Sean A. McCarthy and Jeanette J. McCarthy, Trustees.

2. This option vested 25% on August 9, 2012, and the remaining 75% vested in 36 substantially equal monthly installments thereafter.

3. This option vests in 48 substantially equal monthly installments starting on the last day of February 2013.

4. This option vests in 48 substantially equal monthly installments starting on the last day of January 2015.

5. This option vests in 48 substantially equal monthly installments starting on August 28, 2015, with each additional installment vesting on the last day of the month starting in September 2015.

Remarks:

Exhibit 24.1 - Power of Attorney

	/s/ Cynthia J. Ladd, attorney-in-fact	10/07/2015
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.