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 <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM S-8
</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION STATEMENT </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>UNDER </I></B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>THE
SECURITIES ACT OF 1933 </I></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>CYTOMX THERAPEUTICS, INC. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact name of registrant as specified in its charter) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B>27-3521219</B></TD></TR>
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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(State or Other Jurisdiction of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Incorporation&nbsp;or&nbsp;Organization)</B></P></TD>
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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(IRS Employer</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Identification No.)</B></P></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>343 Oyster Point Blvd. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Suite 100 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>South San
Francisco, CA 94080 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Address of Principal Executive Offices) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>CytomX Therapeutics, Inc. 2015 Equity Incentive Plan </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>CytomX Therapeutics, Inc. Employee Stock Purchase Plan </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Full Title of the Plans) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Sean A. McCarthy, D. Phil. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>President and Chief Executive Officer </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>CytomX Therapeutics, Inc. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>343 Oyster Point Blvd. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Suite 100 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>South San
Francisco, CA 94080 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(650) 515-3185 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name, Address and Telephone Number, including Area Code, of Agent for Service) </B></P>
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<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting
company.&nbsp;See the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer&#148; and &#147;smaller reporting company&#148; in Rule&nbsp;12b-2 of the Exchange Act (Check one): </P>
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<TD VALIGN="bottom">Large&nbsp;accelerated&nbsp;filer</TD>
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<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD></TR>
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<TD VALIGN="bottom">Non-accelerated filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT>&nbsp;&nbsp;(Do not check if a smaller reporting company)</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Smaller&nbsp;reporting&nbsp;company</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
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<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
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<TD VALIGN="bottom" ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Title of Securities</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>to be Registered</B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Amount</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>to be</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Registered<SUP
STYLE="font-size:85%; vertical-align:top">(1)</SUP></B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Proposed</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Maximum</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Offering
Price</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Per Share<SUP STYLE="font-size:85%; vertical-align:top">(4)</SUP></B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Proposed</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Maximum</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Aggregate</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Offering Price<SUP STYLE="font-size:85%; vertical-align:top">(4)</SUP></B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="middle" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Amount of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Registration Fee<SUP STYLE="font-size:85%; vertical-align:top">(4)</SUP></B></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Common stock, par value $0.00001 per share</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:4.00em; text-indent:-2.00em; font-size:10pt; font-family:Times New Roman">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2015 Equity Incentive Plan</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">1,441,328 shares<SUP STYLE="font-size:85%; vertical-align:top">(2)</SUP></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$13.498</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$19,455,045.34</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$1,959.12</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:4.00em; text-indent:-2.00em; font-size:10pt; font-family:Times New Roman">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Employee Stock Purchase Plan</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">360,332 shares<SUP STYLE="font-size:85%; vertical-align:top">(3)
</SUP></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$13.498</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$4,863,761.34</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$489.78</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000">Total</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">1,801,660 shares</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-TOP:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$24,318,806.68</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$2,448.90</TD></TR>
<TR STYLE="font-size:1px; ">
<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="font-size:1px; ">
<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">Pursuant to Rule 416 of the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), this Registration Statement also covers such additional and indeterminate number of securities as may become issuable
pursuant to the provisions of the plans, relating to adjustments for changes resulting from a stock dividend, stock split or similar change. </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">(2)</TD>
<TD ALIGN="left" VALIGN="top">Consists of 1,441,328 additional shares of common stock, par value $0.00001 per share (the &#147;Common Stock&#148;), of CytomX Therapeutics, Inc., a Delaware corporation (the &#147;Registrant&#148;), available for
issuance as a result of the annual evergreen increase for 2016 pursuant to the CytomX Therapeutics, Inc. 2015 Equity Incentive Plan (the &#147;2015 Plan&#148;). </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">(3)</TD>
<TD ALIGN="left" VALIGN="top">Consists of 360,332 shares of Common Stock of the Registrant available for issuance as a result of the annual evergreen increase for 2016 pursuant to the CytomX Therapeutics, Inc. Employee Stock Purchase Plan (the
&#147;ESPP&#148;). </TD></TR></TABLE>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left">(4)</TD>
<TD ALIGN="left" VALIGN="top">Estimated in accordance with Rule 457(h) under the Securities Act solely for the purpose of calculating the registration fee.&nbsp;The price of $13.498 per share represents the average of the high and low prices of the
Common Stock on March&nbsp;1, 2016, as quoted on The NASDAQ Global Select Market. </TD></TR></TABLE> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>EXPLANATORY NOTE </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Registration of Additional Securities </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>2015 Equity Incentive Plan</U></B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The
2015 Plan initially reserved 2,444,735 shares of Common Stock for issuance when it was originally adopted and approved by the Registrant&#146;s Board of Directors and stockholders. The evergreen provision of the 2015 Plan provides that the total
number of shares reserved for issuance under the 2015 Plan will be increased on the first day of each calendar year in an amount equal to 4% of the outstanding shares of common stock on such date or such lesser amount as approved by the Compensation
Committee of the Registrant&#146;s Board of Directors. The Registrant initially registered 2,444,735 shares of Common Stock reserved for issuance under the 2015 Plan on a registration statement on Form S-8 (Registration No. 333-207694) filed with
the Securities and Exchange Commission on October&nbsp;30, 2015 (the &#147;Original Registration Statement&#148;). The Registrant is filing this Registration Statement on Form S-8 to register an additional 1,441,328 shares of Common Stock or 4% of
the outstanding shares of Common Stock as of January&nbsp;1, 2016 under the 2015 Plan as a result of the evergreen increase for 2016. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>Employee
Stock Purchase Plan</U></B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The ESPP initially reserved 354,466 shares of Common Stock for issuance when it was originally adopted and
approved by the Registrant&#146;s Board of Directors and stockholders. The evergreen provision of the ESPP provides that the total number of shares reserved for issuance under the ESPP will be increased on the first day of each calendar year in an
amount equal to the lesser of (i) 675,000 shares, (ii) 1% of the then outstanding shares of Common Stock on such date, or (iii) an amount determined by the Compensation Committee of the Registrant&#146;s Board of Directors. The Registrant initially
registered 354,466 shares of Common Stock reserved for issuance under the ESPP on the Original Registration Statement. The Registrant is filing this Registration Statement on Form S-8 to register an additional 360,332 shares of Common Stock or 1% of
the outstanding shares of Common Stock as of January&nbsp;1, 2016 under the ESPP as a result of the evergreen increase for 2016. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In
accordance with Instruction E of Form S-8, the contents of the Original Registration Statement are hereby incorporated by reference in this Registration Statement on Form S-8; except for Items 3 and 8, which are being updated by this Registration
Statement. </P>

<p Style='page-break-before:always'>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART II </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;3.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Incorporation of Documents By Reference. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Registrant hereby incorporates by
reference in this Registration Statement the following documents and information previously filed with the Securities and Exchange Commission (the &#147;Commission&#148;): </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(1) the Registrant&#146;s annual report on Form 10-K for the fiscal year ended December&nbsp;31, 2015, filed with the Commission on
March&nbsp;7, 2016; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(2) the Registrant&#146;s current reports on Form 8-K, filed with the Commission on January&nbsp;20, 2016 and
March&nbsp;7, 2016 (Item&nbsp;5.02 only), respectively; and </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(3) the description of the Registrant&#146;s Common Stock contained in the
Registrant&#146;s Registration Statement on Form 8-A filed with the Commission on October 6, 2015, pursuant to Section&nbsp;12(b) of the Securities Exchange Act of 1934, as amended (the &#147;Exchange Act&#148;), including any amendment or report
for the purpose of updating such description. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">All documents subsequently filed by the Registrant with the Commission pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act, after the date of this Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the respective dates of filing of such documents (such documents, and the documents
enumerated above, being hereinafter referred to as &#147;Incorporated Documents&#148;). </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Any statement contained in an Incorporated
Document shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed Incorporated Document modifies or supersedes such
statement.&nbsp;Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement. </P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;8.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Exhibits. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Exhibits accompanying this Registration Statement are listed on the
accompanying Exhibit Index. </P>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in South San Francisco, State of California, on this March 7, 2016. </P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="12%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="87%"></TD></TR>


<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3"><B>CYTOMX THERAPEUTICS, INC.</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Sean A. McCarthy</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Sean A. McCarthy, D. Phil.</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Title:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">President and Chief Executive Officer (Principal Executive Officer)</TD></TR>
</TABLE></DIV> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>POWER OF ATTORNEY </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Each of the undersigned officers and directors of CytomX Therapeutics, Inc. (the &#147;Company&#148;), severally constitute and appoint Sean
A. McCarthy and Robert C. Goeltz II, and each of them singly, his or her true and lawful attorneys, with full power to them, and to each of them singly, to sign for him or her and in his or her name in the capacities indicated below, this
Registration Statement, and any and all post-effective amendments to this Registration Statement, and to file or cause to be filed the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange
Commission, granting unto said attorneys, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might
or could do in person, and hereby ratifying and confirming all that said attorneys, and each of them, or their substitute or substitutes, shall do or cause to be done by virtue of this Power of Attorney. This Power of Attorney does not revoke any
power of attorney previously granted by the undersigned, or any of them. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act, this
Registration Statement has been signed below by the following persons in the capacities and on the date indicated below. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="37%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="15%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:52.10pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURES</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:42.35pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>CAPACITY</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:22.30pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>DATE</B></P></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Sean A. McCarthy</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Sean A. McCarthy, D. Phil.</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">President, Chief Executive Officer and Director</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman"><I>(principal&nbsp;executive&nbsp;officer)</I></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Robert C. Goeltz II</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Robert C. Goeltz II</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Chief Financial Officer<I></I></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman"><I>(principal financial officer and</I><I></I></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman"><I></I><I>principal accounting officer)</I></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Hoyoung Huh</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Hoyoung Huh, M.D., Ph.D.</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Chairman of the Board</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Neil Exter</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Neil Exter</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Frederick W. Gluck</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Frederick W. Gluck</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Elaine V. Jones</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Elaine V. Jones, Ph.D.</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Timothy M. Shannon</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Timothy M. Shannon, M.D.</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Matthew P. Young</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Matthew P. Young</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP ALIGN="center">March 7, 2016</TD></TR>
</TABLE>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">

 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>EXHIBIT INDEX </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD></TD>
<TD VALIGN="bottom" WIDTH="7%"></TD>
<TD WIDTH="92%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>EXHIBIT</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>NUMBER</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center"><B>DESCRIPTION</B></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">&nbsp;&nbsp;&nbsp;&nbsp;4.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Amended and Restated Certificate of Incorporation of CytomX Therapeutics, Inc. (incorporated by reference to Exhibit 3.1 of the Registrant&#146;s Current Report on Form 8-K, filed with the Commission on October&nbsp;19,
2015).</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">&nbsp;&nbsp;&nbsp;&nbsp;4.2</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Amended and Restated Bylaws of CytomX Therapeutics, Inc. (incorporated by reference to Exhibit 3.2 of the Registrant&#146;s Current Report on Form 8-K, filed with the Commission on October&nbsp;19, 2015).</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">&nbsp;&nbsp;&nbsp;&nbsp;4.3</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">CytomX Therapeutics, Inc. 2015 Equity Incentive Plan (incorporated by reference to Exhibit 10.5 to Amendment Number 5 to the Registrant&#146;s Registration Statement on Form S-1 (No. 333-206658), filed with the Commission on October
6, 2015).</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">&nbsp;&nbsp;&nbsp;&nbsp;4.4</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">CytomX Therapeutics, Inc. Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.6 to Amendment Number 3 to the Registrant&#146;s Registration Statement on Form S-1 (No. 333-206658), filed with the Commission on
September&nbsp;28, 2015).</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">&nbsp;&nbsp;*5.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Opinion of Sidley Austin <SMALL>LLP</SMALL> with respect to validity of issuance of securities.</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">*23.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Consent of Independent Registered Accounting Firm.</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">*23.2</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Consent of Sidley Austin <SMALL>LLP</SMALL> (included in Exhibit 5.1).</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP ALIGN="center">*24.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Power of Attorney (included on the signature page of the Registration Statement).</TD></TR>
</TABLE> <P STYLE="line-height:8.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000;width:10%">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">*</TD>
<TD ALIGN="left" VALIGN="top">Each document marked with an asterisk is filed herewith. </TD></TR></TABLE>
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FORM S-8
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM S-8
REGISTRATION STATEMENT
UNDER
THE
SECURITIES ACT OF 1933
CYTOMX THERAPEUTICS, INC.
(Exact name of registrant as specified in its charter)
Delaware
27-3521219
(State or Other Jurisdiction of
Incorporation or Organization)
(IRS Employer
Identification No.)
343 Oyster Point Blvd.
Suite 100
South San
Francisco, CA 94080
(Address of Principal Executive Offices)
CytomX Therapeutics, Inc. 2015 Equity Incentive Plan
CytomX Therapeutics, Inc. Employee Stock Purchase Plan
(Full Title of the Plans)
Sean A. McCarthy, D. Phil.
President and Chief Executive Officer
CytomX Therapeutics, Inc.
343 Oyster Point Blvd.
Suite 100
South San
Francisco, CA 94080
(650) 515-3185
(Name, Address and Telephone Number, including Area Code, of Agent for Service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting
company. See the definitions of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act (Check one):
Large accelerated filer
¨
Accelerated filer
¨
Non-accelerated filer
x
(Do not check if a smaller reporting company)
Smaller reporting company
¨
CALCULATION OF REGISTRATION FEE
Title of Securities
to be Registered
Amount
to be
Registered
(1)
Proposed
Maximum
Offering
Price
Per Share
(4)
Proposed
Maximum
Aggregate
Offering Price
(4)
Amount of
Registration Fee
(4)
Common stock, par value $0.00001 per share
•       2015 Equity Incentive Plan
1,441,328 shares
(2)
$13.498
$19,455,045.34
$1,959.12
•       Employee Stock Purchase Plan
360,332 shares
(3)
$13.498
$4,863,761.34
$489.78
Total
1,801,660 shares
$24,318,806.68
$2,448.90
(1)
Pursuant to Rule 416 of the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement also covers such additional and indeterminate number of securities as may become issuable
pursuant to the provisions of the plans, relating to adjustments for changes resulting from a stock dividend, stock split or similar change.
(2)
Consists of 1,441,328 additional shares of common stock, par value $0.00001 per share (the "Common Stock"), of CytomX Therapeutics, Inc., a Delaware corporation (the "Registrant"), available for
issuance as a result of the annual evergreen increase for 2016 pursuant to the CytomX Therapeutics, Inc. 2015 Equity Incentive Plan (the "2015 Plan").
(3)
Consists of 360,332 shares of Common Stock of the Registrant available for issuance as a result of the annual evergreen increase for 2016 pursuant to the CytomX Therapeutics, Inc. Employee Stock Purchase Plan (the
"ESPP").
(4)
Estimated in accordance with Rule 457(h) under the Securities Act solely for the purpose of calculating the registration fee. The price of $13.498 per share represents the average of the high and low prices of the
Common Stock on March 1, 2016, as quoted on The NASDAQ Global Select Market.
EXPLANATORY NOTE
Registration of Additional Securities
2015 Equity Incentive Plan
The
2015 Plan initially reserved 2,444,735 shares of Common Stock for issuance when it was originally adopted and approved by the Registrant's Board of Directors and stockholders. The evergreen provision of the 2015 Plan provides that the total
number of shares reserved for issuance under the 2015 Plan will be increased on the first day of each calendar year in an amount equal to 4% of the outstanding shares of common stock on such date or such lesser amount as approved by the Compensation
Committee of the Registrant's Board of Directors. The Registrant initially registered 2,444,735 shares of Common Stock reserved for issuance under the 2015 Plan on a registration statement on Form S-8 (Registration No. 333-207694) filed with
the Securities and Exchange Commission on October 30, 2015 (the "Original Registration Statement"). The Registrant is filing this Registration Statement on Form S-8 to register an additional 1,441,328 shares of Common Stock or 4% of
the outstanding shares of Common Stock as of January 1, 2016 under the 2015 Plan as a result of the evergreen increase for 2016.
Employee
Stock Purchase Plan
The ESPP initially reserved 354,466 shares of Common Stock for issuance when it was originally adopted and
approved by the Registrant's Board of Directors and stockholders. The evergreen provision of the ESPP provides that the total number of shares reserved for issuance under the ESPP will be increased on the first day of each calendar year in an
amount equal to the lesser of (i) 675,000 shares, (ii) 1% of the then outstanding shares of Common Stock on such date, or (iii) an amount determined by the Compensation Committee of the Registrant's Board of Directors. The Registrant initially
registered 354,466 shares of Common Stock reserved for issuance under the ESPP on the Original Registration Statement. The Registrant is filing this Registration Statement on Form S-8 to register an additional 360,332 shares of Common Stock or 1% of
the outstanding shares of Common Stock as of January 1, 2016 under the ESPP as a result of the evergreen increase for 2016.
In
accordance with Instruction E of Form S-8, the contents of the Original Registration Statement are hereby incorporated by reference in this Registration Statement on Form S-8; except for Items 3 and 8, which are being updated by this Registration
Statement.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
Item 3.
Incorporation of Documents By Reference.
The Registrant hereby incorporates by
reference in this Registration Statement the following documents and information previously filed with the Securities and Exchange Commission (the "Commission"):
(1) the Registrant's annual report on Form 10-K for the fiscal year ended December 31, 2015, filed with the Commission on
March 7, 2016;
(2) the Registrant's current reports on Form 8-K, filed with the Commission on January 20, 2016 and
March 7, 2016 (Item 5.02 only), respectively; and
(3) the description of the Registrant's Common Stock contained in the
Registrant's Registration Statement on Form 8-A filed with the Commission on October 6, 2015, pursuant to Section 12(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), including any amendment or report
for the purpose of updating such description.
All documents subsequently filed by the Registrant with the Commission pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act, after the date of this Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the respective dates of filing of such documents (such documents, and the documents
enumerated above, being hereinafter referred to as "Incorporated Documents").
Any statement contained in an Incorporated
Document shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed Incorporated Document modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.
Item 8.
Exhibits.
The Exhibits accompanying this Registration Statement are listed on the
accompanying Exhibit Index.
SIGNATURES
Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in South San Francisco, State of California, on this March 7, 2016.
CYTOMX THERAPEUTICS, INC.
By:
/s/ Sean A. McCarthy
Name:
Sean A. McCarthy, D. Phil.
Title:
President and Chief Executive Officer (Principal Executive Officer)
POWER OF ATTORNEY
Each of the undersigned officers and directors of CytomX Therapeutics, Inc. (the "Company"), severally constitute and appoint Sean
A. McCarthy and Robert C. Goeltz II, and each of them singly, his or her true and lawful attorneys, with full power to them, and to each of them singly, to sign for him or her and in his or her name in the capacities indicated below, this
Registration Statement, and any and all post-effective amendments to this Registration Statement, and to file or cause to be filed the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange
Commission, granting unto said attorneys, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might
or could do in person, and hereby ratifying and confirming all that said attorneys, and each of them, or their substitute or substitutes, shall do or cause to be done by virtue of this Power of Attorney. This Power of Attorney does not revoke any
power of attorney previously granted by the undersigned, or any of them.
Pursuant to the requirements of the Securities Act, this
Registration Statement has been signed below by the following persons in the capacities and on the date indicated below.
SIGNATURES
CAPACITY
DATE
/s/ Sean A. McCarthy
Sean A. McCarthy, D. Phil.
President, Chief Executive Officer and Director
(principal executive officer)
March 7, 2016
/s/ Robert C. Goeltz II
Robert C. Goeltz II
Chief Financial Officer
(principal financial officer and
principal accounting officer)
March 7, 2016
/s/ Hoyoung Huh
Hoyoung Huh, M.D., Ph.D.
Chairman of the Board
March 7, 2016
/s/ Neil Exter
Neil Exter
Director
March 7, 2016
/s/ Frederick W. Gluck
Frederick W. Gluck
Director
March 7, 2016
/s/ Elaine V. Jones
Elaine V. Jones, Ph.D.
Director
March 7, 2016
/s/ Timothy M. Shannon
Timothy M. Shannon, M.D.
Director
March 7, 2016
/s/ Matthew P. Young
Matthew P. Young
Director
March 7, 2016
EXHIBIT INDEX
EXHIBIT
NUMBER
DESCRIPTION
4.1
Amended and Restated Certificate of Incorporation of CytomX Therapeutics, Inc. (incorporated by reference to Exhibit 3.1 of the Registrant's Current Report on Form 8-K, filed with the Commission on October 19,
2015).
4.2
Amended and Restated Bylaws of CytomX Therapeutics, Inc. (incorporated by reference to Exhibit 3.2 of the Registrant's Current Report on Form 8-K, filed with the Commission on October 19, 2015).
4.3
CytomX Therapeutics, Inc. 2015 Equity Incentive Plan (incorporated by reference to Exhibit 10.5 to Amendment Number 5 to the Registrant's Registration Statement on Form S-1 (No. 333-206658), filed with the Commission on October
6, 2015).
4.4
CytomX Therapeutics, Inc. Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.6 to Amendment Number 3 to the Registrant's Registration Statement on Form S-1 (No. 333-206658), filed with the Commission on
September 28, 2015).
*5.1
Opinion of Sidley Austin
LLP
with respect to validity of issuance of securities.
*23.1
Consent of Independent Registered Accounting Firm.
*23.2
Consent of Sidley Austin
LLP
(included in Exhibit 5.1).
*24.1
Power of Attorney (included on the signature page of the Registration Statement).
*
Each document marked with an asterisk is filed herewith.