Torvu-Sam Shows Safety and Activity Across FRα Expression Levels in PROC

Torvutatug samrotecan (torvu-sam) showed clinically meaningful activity in patients with platinum-resistant ovarian cancer (PROC) regardless of folate receptor α (FRα) expression level, according to results presented at the 2026 European Society for Medical Oncology (ESMO) Congress and discussed in an interview with Funda Meric-Bernstam, MD.

According to Meric-Bernstam, chair of the department of Investigational Cancer Therapeutics at MD Anderson Cancer Center, this suggests that expression testing may not be needed to identify patients who could benefit.

Meric-Bernstam presented extended follow-up from the dose-optimization portion of the phase 1/2a FONTANA trial (NCT05797168). She also presented results from an expansion cohort of patients with ultralow or null FRα expression. Torvu-sam is an FRα-targeted antibody-drug conjugate with a topoisomerase 1 inhibitor payload. Confirmed objective response rates were 61.7% with high FRα expression, 57.1% with low FRα expression, and 48.1% with ultralow or null FRα expression.

Meric-Bernstam described the efficacy signal as very promising across both the expression spectrum and the 3 dose levels tested. She noted that responses were deep and durable, and adverse events including nausea, fatigue, neutropenia, and anemia were most commonly reported.

She contrasted these results with mirvetuximab soravtansine (Elahere), the FDA-approved FRα-directed antibody-drug conjugate. Mirvetuximab soravtansine carries an antitubulin payload with less bystander effect, so it is thought to be most effective in tumors with high FRα expression. According to Meric-Bernstam, its approval requires FRα expression in 75% of tumor cells. FONTANA used the same cutoff to define high expressors. However, efficacy was similar in low expressors, defined as expression in at least 25% of tumor cells.

Meric-Bernstam added that the activity seen in patients with ultralow or null expression points to benefit across the board. She said the findings show that FRα is a meaningful target. They also highlight topoisomerase inhibitors as a powerful payload strategy for antibody-drug conjugates.

Torvu-Sam is moving into phase 3 trials at a dose of 2 mg/kg. In PROC, it will be compared with mirvetuximab soravtansine in patients with high FRα expression and with chemotherapy in patients with lower expression. It will also be evaluated as maintenance therapy. Meric-Bernstam called the results very exciting news for patients.

REFERENCE

1. Meric-Bernstam F, Shapira-Frommer R, Perets R, et al. Updated results from FONTANA: Torvutatug samrotecan (torvu-sam), a folate receptor α (FRα)-targeted antibody-drug conjugate (ADC), in patients (pts) with platinum-resistant ovarian cancer (PROC). Presented at: 2026 ESMO Congress; October 23-27, 2026; Madrid, Spain. Abstract 1245RO.