SOUTH SAN FRANCISCO, CA, USA I September 09, 2024 I CytomX Therapeutics, Inc. (Nasdaq: CTMX), a leader in the field of masked, conditionally activated biologic therapeutics, today announced that the first patient has been dosed with CX-801 monotherapy in a Phase 1 study (NCT06462794) in patients with solid tumors. CX-801 is a dually-masked interferon alpha-2b PROBODY® cytokine with potential broad applicability in both traditionally immune-oncology sensitive as well as insensitive (cold) tumors.

The CX-801 Phase 1 dose escalation study is designed to evaluate safety and signs of clinical activity for CX-801 as monotherapy and in combination with Merck’s (known as MSD outside of the US and Canada) anti-PD-1 therapy KEYTRUDA® (pembrolizumab). In dose escalation, the Phase 1 study will enroll patients with select solid tumors including advanced melanoma, renal cell carcinoma, and head and neck squamous cell carcinoma to inform a potential decision to move into Phase 1b indication-specific dose expansion cohorts.

“Interferon-alpha-2b is a powerful immune-modulating cytokine that has demonstrated clinical activity in multiple cancer types such as metastatic melanoma, renal cancer and bladder cancer but its clinical benefit has been limited by significant toxicities when administered systemically. CX-801 utilizes CytomX’s industry leading conditional activation platform to maintain potency and expand interferon’s therapeutic index to potentially become a foundational component of immuno-oncology combination regimens,” said Wayne Chu, M.D., chief medical officer of CytomX Therapeutics.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA

About CytomX Therapeutics.
CytomX is a clinical-stage, oncology-focused biopharmaceutical company focused on developing novel conditionally activated biologics designed to be localized to the tumor microenvironment. By pioneering a novel pipeline of localized biologics, powered by its PROBODY® therapeutic platform, CytomX’s vision is to create safer, more effective therapies for the treatment of cancer. CytomX’s robust and differentiated pipeline comprises therapeutic candidates across multiple treatment modalities including antibody-drug conjugates (“ADCs”), T-cell engagers, and immune modulators such as cytokines. CytomX’s clinical-stage pipeline includes CX-904, CX-2051 and CX-801. CX-904 is a conditionally activated T-cell-engaging bispecific antibody targeting the epidermal growth factor receptor (EGFR) on tumor cells and the CD3 receptor on T cells. CX-904 is partnered with Amgen in a global co-development alliance. CX-2051 is a conditionally activated ADC directed toward epithelial cell adhesion molecule, EpCAM, with potential applicability across multiple EpCAM-expressing epithelial cancers. CX-2051 was discovered in collaboration with Immunogen, now part of AbbVie. CX-801 is an interferon alpha-2b PROBODY® cytokine with broad potential applicability in traditionally immuno-oncology sensitive as well as insensitive (cold) tumors. CytomX has established strategic collaborations with multiple leaders in oncology, including Amgen, Astellas, Bristol Myers Squibb, Regeneron and Moderna. 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 X (formerly Twitter).

SOURCE: CytomX Therapeutics