UNITED STATES 
        
        SECURITIES AND EXCHANGE COMMISSION 
        
        Washington, D.C. 20549 
        SCHEDULE 14A 
        Proxy Statement Pursuant to Section 14(a) of the 
        
        Securities Exchange Act of 1934 
        
        (Amendment No.  ) 
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                 Filed by the Registrant ☒ 
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                 Filed by a Party other than the Registrant  ☐ 
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Check the appropriate box: 
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                 Preliminary Proxy Statement  
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                 Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))  
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                 Definitive Proxy Statement  
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                 Definitive Additional Materials  
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                 Soliciting Material Pursuant to §240.14a-12  
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                 CytomX Therapeutics, Inc.  
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                 (Name of Registrant as Specified In Its Charter)  
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                 (Name of Person(s) Filing Proxy Statement, if other than the Registrant) 
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Payment of Filing Fee (Check the appropriate box): 
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                 No fee required.  
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                 Fee paid previously with preliminary materials.  
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                 Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11. 
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