CytomX Therapeutics Announces Presentations at 2018 ASCO Annual Meeting

- Preliminary first-in-human data to be presented from PROCLAIM-CX-072 trial of a PD-L1 Probody therapeutic as a monotherapy and in combination with ipilimumab -

SOUTH SAN FRANCISCO, Calif., May 16, 2018 (GLOBE NEWSWIRE) -- 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 that preliminary clinical results from PROCLAIM-072, an ongoing Phase 1/2 trial evaluating CX-072, a Probody therapeutic targeting PD-L1, will be presented at the 2018 Annual Meeting of the American Society of Clinical Oncology (ASCO). The conference will take place from June 1-5 in Chicago, Illinois.

Two posters will detail initial results from two ongoing dose escalation arms of the PROCLAIM-CX-072 trial as monotherapy and in combination with Yervoy® (ipilimumab) in patients with advanced unresectable solid tumors.

“Our goal at CytomX is to reinvent therapeutic antibodies for the treatment of cancer and these first-in-human data represent a key milestone for the Probody platform,” said Sean McCarthy, D.Phil., president and chief executive officer of CytomX Therapeutics. “We look forward to expounding on our initial findings, published today in abstract form, at ASCO. The preliminary data in these abstracts are encouraging as we are observing initial signs of antitumor activity for both CX-072 monotherapy and the ipilimumab combination, in this difficult-to-treat, late-stage patient population for whom approved PD-agents are not available. Furthermore, these data suggest that CX-072 is well tolerated and shows an encouraging, emerging safety profile as a monotherapy and in combination with ipilimumab. Taken together, our preliminary findings are consistent with the Probody hypothesis and align with our vision of transforming lives with safer, more effective therapies.”

CytomX’s ASCO poster presentations will include longer follow-up periods in both the monotherapy and combination arms, as well as data from additional patients treated in combination with ipilimumab and will reflect a data cutoff approximately five months after the abstract data cutoff. Additional data from the PROCLAIM-072 trial is expected during the second half of 2018 and in 2019.

Abstract 3071/Poster #285 - Preliminary Results of the First-In-Human, Dose-Finding PROCLAIM-072 Trial of the PD-L1 Probody Therapeutic CX-072 as Monotherapy in Patients with Advanced Solid Tumors

Karen A. Autio, M.D., MSc., Memorial Sloan Kettering Cancer Center                       
Developmental Therapeutics—Immunotherapy
Monday, June 4, 8:00 – 11:30 a.m.
Hall A

Abstract 3072/Poster #286 - Preliminary Interim Results of the First-In-Human, Dose-Finding PROCLAIM-072 Trial of the PD-L1 Probody Therapeutic CX-072 in Combination with Ipilimumab in Patients with Advanced Solid Tumors

Rachel E. Sanborn, M.D., Earle A. Chiles Research Institute, Providence Cancer Center
Developmental Therapeutics—Immunotherapy
Monday, June 4, 8:00 – 11:30 a.m.
Hall A

Abstract Book -  Preliminary Single-Dose Clinical Pharmacokinetics of an Anti–PD-L1 Probody Therapeutic (Pb-Tx) in Cancer Patients

Pharmacokinetic data published in the conference abstract book suggests that CX-072 is behaving as designed in circulation and that CX-072 circulates predominately in the intact, masked form with low or no binding to the target in the periphery.

CytomX’s posters will be available online under the Events and Presentations section of the CytomX website at the time of presentation at

CytomX will be hosting a conference call and webcast on Monday, June 4, 2018 to discuss the ASCO poster presentations with specific event details to be announced closer to the start of the conference.


PROCLAIM (Probody Clinical Assessment In Man) is an international umbrella program designed to evaluate CytomX Probody therapeutics. The first module is the PROCLAIM-072 clinical program, an open-label, dose-finding Phase 1/2 trial evaluating CX-072 as monotherapy and in combination with Yervoy® (ipilimumab) or Zelboraf®(vemurafenib) in patients with metastatic or locally advanced unresectable solid tumors or lymphomas. CytomX aims to achieve three goals as part of the PROCLAIM-072 clinical trial:

  • Tolerability: Demonstrate that CX-072 is well tolerated in patients, and potentially improves safety, particularly in the combination setting.

  • Anti-cancer activity: Demonstrate initial evidence of CX-072’s anti-cancer activity as monotherapy and in combination.

  • Translational program and Probody platform proof-of-concept: Explore mechanistic aspects of Probody activity in patients as observed in preclinical models.

About CytomX Therapeutics

CytomX Therapeutics is a clinical-stage oncology-focused biopharmaceutical company pioneering a novel class of investigational antibody therapeutics based on its Probody therapeutic technology platform. Probody therapeutics are designed to exploit unique conditions of the tumor microenvironment to more effectively localize antibody binding and activity while limiting activity in healthy tissues. The Company’s pipeline includes cancer immunotherapies against clinically-validated targets, such as CX-072, a PD-L1-targeting Probody therapeutic wholly owned by CytomX, CX-188, a PD-1-targeting Probody therapeutic wholly owned by CytomX and BMS-986249, a CTLA-4-targeting Probody therapeutic partnered with Bristol Myers Squibb. The pipeline also includes first-in-class Probody drug conjugates against high potential targets, such as CX-2009, a CD166-targeting Probody drug conjugate wholly owned by CytomX, and CX-2029, a CD71-targeting Probody drug conjugate partnered with AbbVie, which are considered to be inaccessible to conventional antibody drug conjugates due to their presence on healthy tissue. In addition to its wholly owned programs, CytomX has strategic collaborations with AbbVie, Amgen, Bristol-Myers Squibb Company and ImmunoGen, Inc. For more information, visit or follow us on Twitter.

CytomX Therapeutics Forward-Looking Statements

This press release includes forward-looking statements. Such forward-looking statements involve known and unknown risks, uncertainties and other important factors that are difficult to predict, may be beyond our control, and may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied in such statements. Accordingly, you should not rely on any of these forward-looking statements, including those relating to the potential benefits and efficacy of CytomX’s product candidates, administered separately or in combination, CytomX’s ability to develop and advance product candidates into and successfully complete clinical trials, including CytomX’s Phase 1/2 clinical trials of CX-072, and CytomX’s expectations regarding the availability of clinical data. Risks and uncertainties that contribute to the uncertain nature of the forward-looking statements include: CytomX’s product candidates under its Probody platform, including CX-072, are in the initial stages of clinical development and its other product candidates are currently in preclinical development, and the process by which preclinical and clinical development could potentially lead to an approved product is long and subject to significant risks and uncertainties; the possibility that the results of early clinical trials may not be predictive of future results; the possibility that CytomX’s clinical trials will not be successful; CytomX’s dependence on the success of CX-072; and possible regulatory developments in the United States and foreign countries. Additional applicable risks and uncertainties include those relating to our preclinical research and development, clinical development, and other risks identified under the heading "Risk Factors" included in CytomX’s Quarterly Report on Form 10-Q filed with the SEC on May 9, 2018. The forward-looking statements contained in this press release are based on information currently available to CytomX and speak only as of the date on which they are made. CytomX does not undertake and specifically disclaims any obligation to update any forward-looking statements, whether as a result of any new information, future events, changed circumstances or otherwise.

CytomX Therapeutics


Christopher Keenan
VP, Investor Relations and Corporate Communications


Christine Quern