On January 24, 2024 CytomX Therapeutics, Inc. (Nasdaq: CTMX), a leader in the field of conditionally activated, localized biologics, reported that it has received clearance from the U.S. Food and Drug Administration (FDA) for its Investigational New Drug (IND) applications for the conditionally activated Probody therapeutics CX-2051, an EpCAM-directed ADC, and CX-801, a dually-masked version of interferon-alpha 2b (Press release, CytomX Therapeutics, JAN 24, 2024, View Source [SID1234639455]). CX-2051 has been cleared for the initiation of Phase 1 dose escalation in solid tumors with known EpCAM expression and CX-801 has been cleared for the initiation of Phase 1 dose escalation in solid tumors including melanoma, renal, and head and neck squamous cell carcinoma. Both programs are expected to start Phase 1 studies in the first half of 2024.

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"CX-2051 and CX-801 have the potential to address major unmet needs in oncology and we are excited to advance these programs into Phase 1 clinical studies. CX-2051 is an ADC conjugated to a next-generation topoisomerase-1 inhibitor payload that we believe is tailored to certain EpCAM-expressing tumors, including colorectal cancer," said Wayne Chu, M.D., chief medical officer of CytomX Therapeutics. "CX-801 is designed to overcome previous limitations of interferon-directed therapies due to systemic toxicity and establish CX-801 as a cornerstone of combination regimens, including with checkpoint inhibitors, across a wide range of tumor types," continued Dr. Chu.

"The parallel advancement of these programs toward the clinic demonstrates the continued high productivity of the CytomX team and the versatile, multi-modality nature of our Probody platform. The product design principles behind CX-2051 and CX-801 integrate over a decade of continuous innovation and experience at CytomX," said Sean McCarthy, D.Phil., chief executive officer and chairman of CytomX Therapeutics. "We look forward to the clinical initiation of these programs as we enter a potentially milestone-rich period for the company in 2024 and 2025."

About CX-2051

EpCAM is a high potential oncology target that has been clinically validated by locally administered, previously approved cancer therapies. However, to date, efforts to generate systemically administered anti-EpCAM therapeutics have not been successful due to toxicities in certain epithelial tissues, notably in the gastrointestinal tract. CX-2051, a conditionally activated ADC, is tailored to optimize the therapeutic index for EpCAM-expressing cancers. The cytotoxic payload utilized in CX-2051 is a derivative of camptothecin, a topoisomerase-1 inhibitor, a class of drug that has shown potent clinical anti-cancer activity in the ADC context for multiple targets. CX-2051 has demonstrated a wide predicted therapeutic index and strong preclinical activity and tolerability in multiple preclinical models, including colorectal cancer. Phase 1 clinical initiation in EpCAM expressing solid tumors is expected in the first half of 2024. Further details on the design and preclinical optimization of CX-2051 can be found here:

Link to 2023 World ADC Conference presentation

About CX-801

Interferon-alpha 2b is an immunotherapeutic cytokine that has demonstrated clinical activity and gained regulatory approval previously in multiple cancer types, including metastatic melanoma, renal cancer and bladder cancer. IFNα2b provides a potentially superior approach to activating anti-tumor immune responses compared to other cytokines. CX-801 is a dually masked, conditionally activated version of IFNα2b that has the potential to become a cornerstone of combination therapy for a wide range of tumor types, including in traditionally immuno-oncology sensitive as well as insensitive (cold) tumors. Phase 1 initiation for CX-801 solid tumors including melanoma, renal, and head and neck squamous cell carcinoma anticipated in the first half of 2024. Further details on the design and preclinical optimization of CX-801 can be found here:

Link to 2023 SITC (Free SITC Whitepaper) poster