On October 17, 2025 Marengo Therapeutics, Inc., a clinical-stage biotechnology company pioneering precision immunotherapies for oncology and inflammation & immunology (I&I), reported the first disclosure of interim data from the ongoing Phase 2 trial of its lead program, invikafusp alfa, during a late-breaking oral session at the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) 2025 Annual Meeting, taking place October 17-21, 2025, in Berlin, Germany.

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These highly anticipated results continue to validate Marengo’s first-in-class precision T cell activation platform – a novel approach aimed at fully addressing the significant unmet need for both PD-1 resistant and refractory patients, as well as those for whom PD-1 therapy is not currently indicated.

"The compelling single-agent activity and tumor regression we’re observing across multiple tumor types, particularly in PD-1-resistant tumors, underscore the potential of invikafusp alfa as a new pan-tumor backbone immunotherapy," said Zhen Su, M.D., MBA, Chief Executive Officer of Marengo Therapeutics. "By selectively activating Vβ6/Vβ10 T-cell subsets, we are unlocking distinct immune biology that can reprogram the tumor microenvironment and reinvigorate anti-tumor T cell responses in patient populations who have exhausted current immunotherapies."

As of the July 29, 2025 data cutoff, 55 patients with advanced solid tumors harboring high mutational burden (TMB-H or MSI-H/dMMR) were enrolled across 21 histologies; 44 were efficacy-evaluable. Additional outcomes from the Phase 2 study are outlined below.

Tumor shrinkage: 52% of patients experienced target-lesion regression.
In the TMB-H patients, there was a 20.5% overall response rate (ORR) (9/44) and a 79.5% disease control rate (DCR) (35/44) across six tumor types, including colorectal, gastric, lung, breast, GEJ, and head and neck cancers.
In the MSI-H/dMMR patients, there was a 30% ORR (3/10) and 70% DCR (7/10).
Clinical efficacy was observed in PD-1-resistant/refractory tumors and PD-1 naive tumors where PD-1 was not approved as standard of care, confirming PD-1-independent activity.
The safety profile was consistent with selective T cell activation mechanism of action, and treatment-related AEs were transient and manageable with supportive care.
Building on these clinical data, Marengo is advancing a post-PD-1, biomarker-enriched strategy for invikafusp alfa – continuing the Phase 2 monotherapy expansion in TMB-H or MSI-H/dMMR solid tumors to further characterize the depth and durability of responses across priority indications. In parallel, Marengo is pursuing ongoing regulatory interactions, including recently securing U.S. FDA Fast Track designation in TMB-H mCRC.

To reach broader, frontline populations beyond biomarker TMB-H in large indications, the company is also progressing a Phase 2 combination with Trodelvy (TROP2-directed ADC) in TNBC and HR+/HER2– breast cancer to evaluate synergy in ADC and IO settings.

Invikafusp alfa is a first-in-class, bispecific dual T-cell agonist designed to selectively activate and expand Vβ6/Vβ10 T-cell subsets, which represent ~10% of tumor-infiltrating lymphocytes (TILs). Marengo’s lead asset was designed to restore and amplify anti-tumor immunity in patients who have progressed on or are insensitive to prior immune checkpoint blockade, and it has demonstrated rapid progress to date. Phase 1/2 results of the STARt-001 clinical trial evaluating invikafusp alfa in antigen-rich solid tumors were first presented at SITC (Free SITC Whitepaper) 2024, followed by disclosure of the recommended Phase 2 dose (RP2D) selection rationale and early clinical activity at AACR (Free AACR Whitepaper) 2025.

(Press release, Marengo Therapeutics, OCT 17, 2025, View Source;resistant-solid-tumors-as-a-late-breaking-oral-presentation-at-esmo-2025-302587142.html [SID1234656753])