CytomX Therapeutics, Inc. (CTMX) announced that the first patient has been dosed in the combination arm of its ongoing Phase 1 clinical trial, evaluating CX-801 in combination with KEYTRUDA or pembrolizumab for the treatment of metastatic melanoma.
CX-801 is a dually masked interferon alpha-2b PROBODY cytokine, designed to localize immune activation within tumors while reducing systemic toxicity.
This proprietary approach aims to enhance tolerability and enable new combination strategies with checkpoint inhibitors like KEYTRUDA.
The combination arm follows successful progression through the first three CX-801 monotherapy dose escalation cohorts, clearing the way for combination dosing.
The Phase 1 trial will evaluate safety and early signs of clinical activity in patients with advanced melanoma, particularly those with PD-1 refractory disease.
"PD-1 refractory melanoma remains an area of significant unmet need," said Dr. Wayne Chu, Chief Medical Officer at CytomX. "We believe CX-801, with its localized immune activation, is well positioned to enhance the effect of checkpoint blockade."
Initial translational and biomarker data from the Phase 1a portion of the trial are expected in the second half of 2025.
CX-801 is part of CytomX's broader pipeline of conditionally activated biologics targeting the tumor microenvironment, developed using its proprietary PROBODY platform.
The company is also advancing CX-2051, a masked EpCAM-targeted ADC, and maintains active collaborations with partners including Amgen, Regeneron, Moderna, Astellas, and Bristol Myers Squibb.
Currently, CTMX is trading at $2.09, up by 3.40 percent on the Nasdaq.
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