Sutro Biopharma announced updated data from its Phase 1b study of luveltamab tazevibulin (luvelta) in combination with bevacizumab for patients with epithelial ovarian cancer (EOC) at the 2024 European Society for Medical Oncology (ESMO) Congress. The results indicate encouraging antitumor activity, with a 56% objective response rate (ORR) observed at the recommended Phase 2 dose (RP2D) of 4.3 mg/kg luvelta plus 15 mg/kg bevacizumab every three weeks.
Promising Antitumor Activity
The study enrolled 18 patients, with one still on treatment. Among 17 RECIST evaluable patients, the combination of luvelta and bevacizumab demonstrated an overall response rate of 35%. Notably, the antitumor activity was observed regardless of Folate Receptor-α (FRα) expression levels, including in patients with no FRα expression and those previously treated with bevacizumab. The median duration of response was 9.3 months.
Jane Chung, Sutro’s President and Chief Operating Officer, stated, “We are encouraged by these results achieved with luvelta in combination with bevacizumab, which may offer the opportunity to benefit ovarian cancer patients regardless of FRα expression.”
Dosage and Safety Profile
At the RP2D (4.3 mg/kg), the objective response rate was 56% (5/9 patients). In contrast, no responses were observed at 3.5 mg/kg (0/6 patients), while 50% (1/2 patients) responded at 5.2 mg/kg. The safety profile of the combination was consistent with that of each agent alone, with neutropenia being the most common adverse event.
Ongoing Expansion Phase
The expansion phase of the study is ongoing at the RP2D, with an additional 23 patients enrolled. Initial data from this expansion are expected in the first half of 2025. This phase aims to further evaluate the efficacy and safety of the luvelta and bevacizumab combination.
About Luveltamab Tazevibulin
Luveltamab tazevibulin (luvelta) is an antibody-drug conjugate (ADC) targeting FRα, designed to treat a broad range of ovarian cancer patients, including those with lower FRα-expression who may not be eligible for existing FRα-targeted therapies. Sutro's XpressCF® platform is used to develop and manufacture luvelta, ensuring precise positioning of four hemiasterlin cytotoxins per antibody for efficient tumor delivery and systemic stability.
Currently, luvelta is being evaluated in a Phase 2/3 registration-directed study (REFRαME-O1) for patients with platinum-resistant ovarian cancer, as well as in trials for endometrial cancer, non-small cell lung cancer, and in combination with bevacizumab for ovarian cancer. Sutro anticipates initiating a Phase 2/3 study (REFRαME-P1) for CBF/GLIS2 acute myeloid leukemia in pediatric patients in the second half of 2024. The FDA has granted luvelta Fast Track designation for Ovarian Cancer, along with Orphan and Rare Pediatric Disease designations for CBF/GLIS2 Pediatric AML.
