Cambridge, Mass. – October 15, 2026 -- The U.S. Food and Drug Administration has granted a second Fast Track Designation to Marengo Therapeutics' invikafusp alfa, extending the drug's expedited status from one tumor type to all tumor mutational burden high (TMB-H) solid tumors regardless of tissue of origin.
The new designation covers unresectable, locally advanced or metastatic TMB-H solid tumors that have progressed after prior treatment, including immune checkpoint inhibition, and for which no satisfactory treatment options exist. Marengo believes invikafusp alfa is the first immuno-oncology T-cell agonist to receive Fast Track Designation in a biomarker-defined, tissue-agnostic indication.
Second designation broadens a January 2025 colorectal cancer grant
The first Fast Track Designation, granted in January 2025, was limited to TMB-H colorectal cancer. The pan-tumor designation is backed by objective responses in the ongoing Phase 1/2 STARt-001 study across colorectal, gastric, breast, urothelial, endometrial, gastroesophageal, head and neck, and lung cancers. Initial data were presented at the Society for Immunotherapy of Cancer (SITC) 2025 Annual Meeting.
Updated Phase 2 data go to ESMO on October 23
Marengo will present updated Phase 2 STARt-001 results in an oral session at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid on October 23. The Phase 2 portion uses biomarker-enriched cohorts, including TMB-H and MSI-H, to assess activity across tumor types. Phase 2 expansion is continuing in tumors resistant to immune checkpoint blockade.
Mechanism targets patients who fail PD-1 therapy
Invikafusp alfa (STAR0602) is a first-in-class bispecific dual T-cell agonist from Marengo's STAR platform. It is designed to activate a common Vβ T-cell subset found in all cancers, expanding clonally diverse effector memory T cells instead of releasing a checkpoint on exhausted ones.
Eric Rubin, a member of Marengo's Scientific Advisory Board and former Merck Senior Vice President of Global Clinical Oncology who led initial pembrolizumab development, said many TMB-H patients do not respond to PD-1 blockade or progress after it, leaving few options.
Combination work with an antibody-drug conjugate targets earlier lines
Chief Development Officer Ke Liu said the company has seen monotherapy activity in heavily pretreated patients whose tumors were insensitive to checkpoint inhibitors or progressed after PD-1-directed therapy. Marengo is also evaluating invikafusp alfa with standard-of-care therapies, including an antibody-drug conjugate, to support use in earlier lines.
Fast Track Designation provides more frequent FDA communication and, for drugs meeting relevant criteria, eligibility for rolling review, Accelerated Approval and Priority Review. Invikafusp alfa remains investigational and is not approved by the FDA or any other regulatory authority.