Marengo Therapeutics reported initial Phase IIa results from the STARt-002 trial of invikafusp alfa combined with sacituzumab govitecan (TRODELVY) in heavily pretreated metastatic breast cancer at the AACR Annual Meeting on April 20, 2026, with interim findings showing confirmed complete responses across both metastatic triple-negative breast cancer (mTNBC) and HR+/HER2− subtypes, the company said.
The data, presented as a late-breaking abstract, showed confirmed complete responses in patients who had not responded to any prior therapy, according to Marengo. No specific response rates, patient numbers, or duration of response figures were disclosed in the company's announcement. The safety profile was described as consistent with the known profiles of the individual agents. Pharmacodynamic analyses indicated that invikafusp alfa maintains its mechanism of action in the combination setting, with the company reporting robust and selective expansion of Vβ6/Vβ10 T cells. No dose-limiting toxicity data or grade-specific adverse event rates were provided.
The STARt-002 trial (NCT06827613) is an open-label, multicenter Phase Ib/IIa study enrolling adults with unresectable, locally advanced, or metastatic breast cancer across two expansion cohorts — one in mTNBC and one in HR+/HER2− disease — following a safety lead-in phase. The trial is actively enrolling at cancer centers across North America, with completion expected later in 2026. These data are interim, drawn from a subset of enrolled patients, and no comparative arm exists given the open-label design. The recommended Phase II dose has been selected, according to the abstract title, though dosing details were not disclosed in the press release.
Invikafusp alfa is a multispecific antibody-fusion molecule designed to selectively activate Vβ6/Vβ10 T cell subsets by combining TCR engagement with co-stimulatory signaling, a mechanism distinct from checkpoint inhibition. Sacituzumab govitecan, the combination backbone, produced a median overall survival of 12.1 months versus 6.7 months in previously treated mTNBC in the ASCENT trial.
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