Marengo Reports Early Phase 2 Activity for Invikafusp Alfa Combination; Advances STAR Program at AACR 2026

Marengo Therapeutics presented interim data from the ongoing STARt-002 Phase 1b/2a trial¹ evaluating invikafusp alfa in combination with sacituzumab govitecan (brand name Trodelvy) in patients with unresectable, locally advanced, or metastatic breast cancer. The study includes both triple-negative (TNBC) and hormone receptor–positive/HER2-negative (HR+/HER2−) expansion cohorts following a safety lead-in. STARt-002 aims to improve outcomes for metastatic breast cancer patients who have limited treatment options.

Early Phase 2 responses observed

According to Marengo, the data showed confirmed complete responses in heavily pretreated patients with metastatic breast cancer for both TNBC and HR+/HER2 disease.

Responses were observed in patients who had received multiple prior lines of therapy, including those who had progressed on standard options.

"In a heavily pretreated metastatic breast cancer population, the observation of confirmed complete responses is notable and warrants attention," said Erika Hamilton, M.D., Chief Development Officer, Late Phase and Director of Breast Cancer Research. "While these are early data, the activity observed across both TNBC and HR+/HER2− subtypes, along with a safety profile consistent with the individual agents, supports further clinical evaluation of this combination."

Safety profile consistent with individual agents

The combination has so far shown a safety profile consistent with that of each agent alone, with no new safety signals reported in the interim analysis.

Pharmacodynamic data indicated that invikafusp alfa maintained its mechanism of action in the combination setting, with selective expansion of Vβ6 and Vβ10 T-cell subsets observed.

The regimen combines sacituzumab govitecan, an antibody–drug conjugate that delivers a topoisomerase inhibitor payload, with invikafusp alfa, a dual T-cell agonist designed to activate defined T-cell subsets through T-cell receptor and co-stimulatory signaling.

STAR platform background and lead candidate

Invikafusp alfa (STAR0602) is the lead candidate from Marengo’s STAR platform, a multi-specific antibody-fusion system designed to target germline-

encoded variable Vβ regions of the T-cell receptor (TCR). The platform links these targeting domains to T-cell co-stimulatory moieties to enable selective T-cell activation.

The approach is intended to expand clonally diverse effector memory T-cell populations by combining non-clonal TCR engagement with co-stimulation in a single molecule. In preclinical studies, STAR0602 demonstrated anti-tumor activity in both murine and human ex vivo models.

Enrollment in STARt-002 is ongoing at sites across North America, with completion expected later this year.

Second STAR candidate enters clinic

Marengo also disclosed IPN01203/STAR0501, the second clinical-stage program from its STAR platform, developed in collaboration with Ipsen.

The candidate was featured in the AACR “New Drugs on the Horizon” session². It is designed to selectively activate Vβ6 T cells through TCR and IL-15 receptor signaling pathways, with the goal of enhancing tumor-targeting immune activity.

IPN01203 is currently being evaluated in a Phase I/II dose-escalation and expansion study sponsored by Ipsen.

Platform continues to advance multiple programs

The STAR platform is built on a library of antibodies targeting defined TCR Vβ regions, enabling selective modulation of T-cell subsets rather than broad immune activation.

Together, the Phase 2 data for invikafusp alfa and the advancement of IPN01203 highlight continued clinical progress for Marengo’s T-cell–targeting approach across early- and mid-stage development.

References

1. Isakoff, S.; Bedard, P.; Martynova, A. et al. (2026 February 17). PS5-09-16: A phase 1b/2 clinical investigation of invikafusp alfa (STAR0602), a first-in-class dual T-cell agonist, in combination with sacituzumab govitecan in patients with metastatic TNBC or HR+/HER2- MBC (START-002 trial). AACR Journals. https://aacrjournals.org/clincancerres/article/32/4_Supplement/PS5-09-16/773263/PS5-09-16-A-phase-1b-2-clinical-investigation-of

2. Ipsen showcases transformative potential of early immuno-oncology pipeline at AACR. (2026, March 18). Ipsen.com. https://www.ipsen.com/press-release/ipsen-showcases-transformative-potential-of-early-immuno-oncology-pipeline-at-aacr-3257884/