- Presentation at World ADC Conference in San Diego -

- CX-2051 integrates CytomX core platform expertise to potentially maximize therapeutic window -

SOUTH SAN FRANCISCO, Calif., Sept. 07, 2022 (GLOBE NEWSWIRE) -- CytomX Therapeutics, Inc. CTMX, a leader in the field of conditionally activated oncology therapeutics, today announced that the Company presented advances within its conditionally-activated ADC portfolio, including the next generation EpCAM-ADC, CX-2051, at the World ADC conference taking place September 6-9, 2022, in San Diego, CA.

"The momentum in the field of ADC therapeutics is incredibly exciting and holds great promise for the innovation and development of novel oncology therapeutics. Our pioneering work and experience in applying our versatile Probody^® platform to the ADC modality has the potential to expand the universe of addressable targets and to further increase the therapeutic window of future molecules entering the clinic," said Marcia P. Belvin, Ph.D., senior vice president and head of research at CytomX. "CX-2051, our EpCAM-targeted, conditionally activated ADC, is strategically tailored to optimize the therapeutic index for systemic treatment of EpCAM-expressing epithelial cancers, which is an area of high unmet need where, to date, efforts have not been successful due to dose-limiting toxicities."

"Our strategy with CX-2051 is to match payload mechanism of action with tumor sensitivity, and we have selected the topoisomerase-1 inhibitor, camptothecin, as the payload for our newest ADC," Dr. Belvin continued. "Topoisomerase-1 inhibitor-conjugated ADCs are showing impressive clinical activity, and importantly, the safety profiles of camptothecin and its derivatives have been well characterized. Additionally, two camptothecin derivatives, irinotecan and topotecan, have been approved by the U.S. Food and Drug Administration for clinical use - irinotecan for pancreatic and colorectal cancer, and topotecan for ovarian, cervical, and small cell lung cancer. We plan to pursue multiple indications with this new therapeutic candidate and look forward to progressing to an investigational new drug application submission in the second half of 2023."

Presentation highlights include:

• Review of clinical activity for the conditionally activated ADCs CX-2029 and praluzatamab ravtansine (CX-2009), targeting CD71 and CD166, respectively. CD71 and CD166 have historically been inaccessible targets for traditional ADCs due to their high expression levels on normal tissues. The data presented demonstrate clinical anti-cancer activity and a therapeutic window for these previously undruggable targets.
• The molecular structure of CX-2051, a masked, conditionally activated, EpCAM-targeting ADC with a next generation camptothecin-based linker payload. CX-2051 highlights the potential for CytomX's Probody technology to unlock a new ADC target (EpCAM/Trop-1), which is a target that has previously yielded promising clinical results only through locally administered therapies.
• CX-2051 preclinical data indicating strong anti-cancer activity and tolerability with a favorable predicted therapeutic index.
  

The full presentation is available at the following link:

Tailoring the Selection of Target, Payload, & Tumor Type to Maximize the Therapeutic Index of Conditionally Activated ADCs
Marcia P. Belvin, Ph.D., Senior Vice President, Head of Research, CytomX Therapeutics
Presentation Link

About CytomX Therapeutics, Inc.
CytomX is a clinical-stage, oncology-focused biopharmaceutical company dedicated to destroying cancer differently. By pioneering a novel class of conditionally activated biologics, powered by its Probody® technology platform, CytomX's goal is to transcend the limits of current cancer treatments. CytomX's robust and differentiated pipeline comprises seven therapeutic candidates across multiple treatment modalities. Three of these candidates are in Phase 2 studies across multiple cancer types, including CX-2029 and praluzatamab ravtansine. CX-2029 is an investigational conditionally activated antibody-drug conjugate (ADC) directed toward CD71, which has demonstrated encouraging antitumor activity in patients with squamous non-small cell lung cancer and is being developed in collaboration with AbbVie. Praluzatamab ravtansine is an investigational conditionally activated ADC directed toward CD166 and is being studied in patients with advanced breast cancer. CytomX's clinical 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, as well as CX-904, a conditionally activated T-cell-engaging bispecific antibody targeting the epidermal growth factor receptor on tumor cells and the CD3 receptor on T cells, which is partnered with Amgen. In addition, CytomX has a diverse preclinical portfolio of wholly-owned assets such as CX-801, an interferon alpha-2b Probody cytokine that has broad potential applicability in traditionally immuno-oncology sensitive as well as insensitive (cold) tumors and CX-2051, a conditionally activated ADC directed toward EpCAM, with potential applicability across multiple EpCAM-expressing epithelial cancers. CytomX has established strategic collaborations with multiple leaders in oncology, including AbbVie, Amgen, Astellas, and Bristol Myers Squibb. For more information about CytomX and how it is working to make conditionally activated treatments the new standard-of-care in the fight against cancer, visit www.cytomx.com and follow us on LinkedIn and Twitter.

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, including those related to the potential of Antibody Drug Conjugates, Probody Drug Conjugates or CX-2051. Accordingly, you should not rely on any of these forward-looking statements, including those relating to the potential benefits, safety and efficacy or progress of CytomX's or any of its collaborative partners' product candidates, including praluzatamab ravtansine, CX-2029, BMS-986249, BMS-986288, pacmilimab, CX-904, CX-801, and CX-2051, the potential benefits or applications of CytomX's Probody platform technology, CytomX's ability to develop and advance product candidates into and successfully complete clinical trials, including the ongoing and planned clinical trials of praluzatamab ravtansine, CX-2029, BMS-986249, BMS-986288, pacmilimab, and CX-904, and the timing of the commencement of clinical trials, initial and ongoing data availability, investigational new drug applications and other development milestones. Risks and uncertainties that contribute to the uncertain nature of the forward-looking statements include: the unproven nature of CytomX's novel Probody Platform technology; CytomX's clinical trial product candidates 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, including the risk that the COVID-19 worldwide pandemic may continue to negatively impact the business, research and clinical operations of CytomX or its partners, including the development of preclinical drug candidates due to delays in and disruption of research activities and the development of clinical drug candidates due to delays in or disruption of clinical trials, including impacts on the enrollment of patients in clinical trials or other clinical trial disruptions; the possibility that the results of preclinical research and early clinical trials may not be predictive of future results; the possibility that CytomX's clinical trials will not be successful; the possibility that current preclinical research may not result in additional product candidates; CytomX's dependence on the success of praluzatamab ravtansine, CX-2029, BMS-986249, BMS-986288, pacmilimab, CX-904, CX-801, and CX-2051; CytomX's reliance on third parties for the manufacture of the Company's product candidates; 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 August 4, 2022. 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.

Probody is a U.S. registered trademark of CytomX Therapeutics, Inc.

CytomX Contact:
Chris Ogden
Senior Vice President, Head of Finance
cogden@cytomx.com
(317) 767-4764

Investor and Media Contact:
Stern Investor Relations
Stephanie Ascher
stephanie.ascher@sternir.com
(212) 362-1200