SOUTH SAN FRANCISCO, Calif. — November 4, 2025 — Leads & Copy — CytomX Therapeutics, Inc. (Nasdaq: CTMX) announced that initial data from its ongoing Phase 1 study of CX-801 in patients with advanced melanoma will be presented at the Society for Immunotherapy of Cancer (SITC) 40th Anniversary Annual Meeting from November 7-9, 2025.
CX-801 (PROBODY® interferon alpha-2b) Phase 1 data demonstrate activation of tumor-selective interferon signaling in patients with advanced melanoma. The data support CX-801’s mechanism of action and the ongoing Phase 1 combination study with KEYTRUDA® (pembrolizumab).
Marcia Belvin, Ph.D., SVP, chief scientific officer of CytomX Therapeutics, said that CX-801 was intentionally designed to unlock the powerful immune-modulating effects of interferon alpha-2b by leveraging the PROBODY® therapeutic platform. She added that she’s excited to share initial Phase 1 biomarker data for CX-801, which suggest the molecule is working as designed by inducing tumor-localized activation of immune cell populations and interferon-stimulated genes in paired tumor biopsies, including PD-1 and PD-L1.
Dr. Wayne Chu, M.D., chief medical officer of CytomX Therapeutics, said that he’s pleased with the Phase 1 progress for CX-801 to-date, including initial evidence that CX-801 is generally well tolerated and can modulate the immune tumor microenvironment in patients with metastatic melanoma refractory to prior immune checkpoint inhibitor therapy. He added that these initial data support the rationale for the ongoing Phase 1 combination study of CX-801 combined with KEYTRUDA® in melanoma, an area of significant unmet need. He looks forward to providing Phase 1 clinical data of CX-801 combined with KEYTRUDA® in 2026.
Presentations include a CX-801 poster presentation and a preclinical masked T-cell engager targeting CDH3 presentation.
Contact:
Chris Ogden
SVP, Chief Financial Officer
cogden@cytomx.com
Source: CytomX Therapeutics, Inc.
