CTMX CytomX Therapeutics Inc

CytomX Therapeutics, Inc. (Nasdaq: CTMX), a clinical-stage oncology-focused biopharmaceutical company pioneering a novel class of investigational antibody therapeutics based on its Probody® therapeutic technology platform, today announced the selection of seven presentations to be featured as part of the American Society of Clinical Oncology’s (ASCO) ASCO20 Virtual Scientific Program taking place from May 29 - May 31, 2020.

The titles of the abstracts are currently available on ASCO’s 2020 Digital Scientific Program, with full abstracts, including the dates and times of presentations, scheduled for publication on May 13, 2020.

A list of accepted abstracts by CytomX and its partners is provided below.

ASCO 2020 Clinical Highlights From Across the CytomX Probody Portfolio

• Preliminary Data from Phase 1/2 Trial of CX-2029, a CD71 Targeting Probody Drug Conjugate, Partnered with AbbVie

• Preliminary Phase 1 Clinical Data Presented by Bristol Myers Squibb from the Ongoing First-in-Human Phase 1/2a trial of BMS-986249, a Probody Version of the anti-CTLA-4 Antibody ipilimumab

• Updated Data from the Phase 1/2 Trial of CX-2009, an Anti-CD166 Probody Drug Conjugate

• Updated Clinical Data from the Phase 1/2 Trial of CX-072, an Anti-PD-L1 Probody Therapeutic, as Monotherapy, in Selected Tumor Types and in Combination with ipilimumab

“Our presence at ASCO this year highlights the strong clinical progress made by CytomX and our partners in exploring the broad potential of the novel Probody technology platform,” said Amy Peterson, M.D., chief development officer of CytomX Therapeutics. “We look forward to updating the oncology community on this progress and on next steps towards our vision of transforming the lives of patients with cancer.”

CX-2029, An Anti-CD71 Probody Drug Conjugate

Presentation Title: CX-2029, a PROBODY Drug Conjugate Targeting CD71 (Transferrin Receptor): Results from a First-in-Human Study (PROCLAIM-CX-2029) in Patients (Pts) With Advanced Cancer Session Title: Developmental Therapeutics—ImmunotherapyAbstract: 3502 Session Type: Oral Presentation

CX-072, An Anti-PD-L1 Probody Therapeutic

Presentation Title: PROCLAIM-CX-072: Analysis of Patients With Advanced Solid Tumors Receiving Long-Term Treatment With CX-072, a PD-L1 PROBODY Therapeutic, as a Single Agent or in Combination With Ipilimumab. Session Title: Developmental Therapeutics—Immunotherapy Abstract: 2005 Session Type: Oral Presentation Presentation Title: Evidence of Intratumoral Localization, Activation, and Immunomodulatory Effect of CX-072, a PROBODY Therapeutic Targeting PD-L1, in a Phase 1/2 Trial Session Title: Developmental Therapeutics—Immunotherapy Abstract: 3108 Session Type: Poster Presentation (Poster #172) Presentation Title: Preliminary Population Pharmacokinetics Supports Phase 2 Dose Selection for Masked Anti–PD-L1 Antibody CX-072 Session Title: Developmental Therapeutics—Immunotherapy Abstract: 3602 Session Type: Poster Presentation (Poster #332)

CX-2009, An Anti-CD166 Probody Drug Conjugate

Presentation Title: CX-2009, A CD166-Directed PROBODY Drug Conjugate (PDC): Results From the First-in-Human Study in Patients With Advanced Cancer Including Breast Cancer Session Title: Developmental Therapeutics—Immunotherapy Abstract: 526 Session Type: Poster Presentation (Poster #18) Presentation Title: Preliminary Clinical Pharmacokinetics and Dose-Response to Support a Phase 2 Dose Selection for CX-2009: A Masked PROBODY Drug Conjugate to CD166 Session Title: Developmental Therapeutics—Immunotherapy Abstract: 3599 Session Type: Poster Presentation (Poster #329)

BMS-986249, An Anti-CTLA-4 Probody Therapeutic

Presentation Title: Anti–CTLA-4 probody BMS-986249 Alone or in Combination with Nivolumab in Patients with Advanced Cancers: Initial Phase 1 Results Session Title: Developmental Therapeutics—Immunotherapy Abstract: 3058 Session Type: Poster Presentation (Poster #122)

About CytomX Therapeutics CytomX is a clinical-stage, oncology-focused biopharmaceutical company with a vision of transforming lives with safer, more effective therapies. We are developing a novel class of investigational antibody therapeutics, based on our Probody® technology platform, for the treatment of cancer. Probody therapeutics are designed to remain inactive until they are activated by proteases in the tumor microenvironment. As a result, Probody therapeutics are intended to bind selectively to tumors and decrease binding to healthy tissue, to minimize toxicity and potentially create safer, more effective therapies. As leaders in the field, our innovative technology is designed to turn previously undruggable targets into druggable targets and to enable more effective combination therapies. CytomX and its partners, comprised of leading biotechnology and pharmaceutical companies, have developed a robust pipeline of potential first-in-class therapeutic candidates against novel, difficult to drug targets and potential best-in-class immunotherapeutic candidates against clinically validated targets. The CytomX clinical stage pipeline includes first-in-class product candidates against previously undruggable targets, including a CD166-targeting Probody drug conjugate wholly owned by CytomX (CX-2009) and a CD71-targeting Probody drug conjugate partnered with AbbVie (CX-2029). CD166 and CD71 are among cancer targets that are considered to be inaccessible to conventional antibody drug conjugates due to their presence on many healthy tissues. The CytomX clinical stage pipeline also includes cancer immunotherapeutic candidates against validated targets such as the CTLA-4-targeting Probody therapeutics, BMS-986249 and BMS-986288, partnered with Bristol Myers Squibb. CytomX has strategic drug discovery and development collaborations with AbbVie, Amgen, Astellas and Bristol Myers Squibb. For additional information about CytomX Therapeutics, visit www.cytomx.com and follow us on LinkedIn and Twitter.

Probody is a U.S. registered trademark of CytomX Therapeutics, Inc. Investor and Media Contact:

Christopher Keenan VP, Investor Relations and Corporate Communications ckeenan@cytomx.com 650-383-0823