ESMO : Brenus Pharma's Novel In Vivo Immunotherapy STC-1010 Shows Safety, Activating T Cells in First-Line MSS Metastatic Colorectal Cancers With 2 Complete Response

Brenus Pharma, a clinical-stage biotech company, announced first data from the Phase Ia dose escalation of BreAK CRC-001. Nine unresectable patients were treated; 89% had liver metastases and 89% KRAS-mutant tumors, a population refractory to immunotherapy. Median follow-up: 8 months (1–14; data cut-off 6/08/2026).
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95% of metastatic colorectal cancers are pMMR/MSS tumors, poorly immunogenic and resistant to immunotherapy. STC-1010, the company’s lead in vivo DC-engager, is designed to make these “cold” tumors visible to immune cells.

• Safety: no dose-limiting toxicity, only grade 1–2 related adverse events.
• Clinical activity (seven evaluable patients, RECIST 1.1): 100% disease control, 57% objective response rate (4/7).
• 43% of patients became operable (3/7): two with no evidence of disease afterward.
• Molecular profile: ctDNA dropped by up to 97% within two months, TP53 and KRAS mutations near undetectable.
• Immune activity (first six patients): STC-1010 regimen nearly quadrupled cytotoxic CD8+ T-cell infiltration in tumors (+285% T2 vs baseline) and increased the CD4+/Treg ratio 2.5-fold (p<0.05). Circulating T cells increased, consistent with trafficking to the tumor. In the presented patient case, profiling showed intratumoral antigen-presenting macrophages, a peripheral shift of T cells toward a memory phenotype, and expansion of tumor-reactive PD-1+CD39+ cells.

"These data validate STC-1010’s safety. They reinforce our hypotheses with early efficacy signals and the potential to improve the therapeutic landscape of cold tumor,” said Paul BRAVETTI, CEO of Brenus Pharma.

“Making initially unresectable patients eligible for surgery is what matters most in first-line metastatic colorectal cancer. Seeing it alongside immune activation in MSS tumors is a remarkable signal for patients,” said Prof. François GHIRINGHELLI, Centre Georges-François Leclerc, Dijon, principal investigator.