Sutro Biopharma Updates Phase 1b Luvelta-Bevacizumab Data at ESMO 2024

Sutro Biopharma, Inc., a clinical-stage oncology company focused on innovative antibody drug conjugates (ADCs), has provided an update on its Phase 1b study of luveltamab tazevibulin (luvelta) in combination with bevacizumab for patients with epithelial ovarian cancer (EOC). This update was presented at the 2024 European Society For Medical Oncology (ESMO) Congress in Barcelona, Spain.

The study has shown promising antitumor activity for the combination of luvelta and bevacizumab in patients with advanced ovarian cancer, irrespective of Folate Receptor-α (FRα) levels and prior bevacizumab treatment. The overall response rate (ORR) was 35%, indicating the potential for a non-biomarker driven treatment approach for EOC patients. The study is currently in its expansion phase at the recommended Phase 2 dose (RP2D) of luvelta (4.3 mg/kg) combined with bevacizumab (15 mg/kg). So far, 23 additional patients have been enrolled, with initial data anticipated in the first half of 2025.

Jane Chung, President and Chief Operating Officer of Sutro, expressed optimism about the results. "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," she said. She also highlighted that the combination therapy could extend the benefits of luvelta monotherapy to more cancer patients. The company is eager to share the preliminary results from the expansion phase in early 2025.

Among the enrolled 18 patients, one remains under treatment. In the group of 17 RECIST evaluable patients, the following observations were made:
- At the RP2D (4.3 mg/kg), an Objective Response Rate (ORR) of 56% (5/9) was seen.
- No patients (0/6) responded at 3.5 mg/kg.
- At a dose of 5.2 mg/kg, 50% (1/2) showed a response.
- The overall population had an ORR of 35% (6/17) with a median response duration of 9.3 months.
- For patients with at least 25% FRα expression, an ORR of 44% (4/9) was observed.

Safety results were consistent with previous findings for luvelta and bevacizumab used separately. The most frequent adverse event was neutropenia, and no new safety concerns were identified.

Luveltamab tazevibulin, known as luvelta, targets the Folate Receptor Alpha (FRα) and is designed to treat a broad spectrum of ovarian cancer patients, including those with low FRα expression who are not suitable for existing therapies. Developed using Sutro’s cell-free XpressCF® platform, luvelta is a homogeneous ADC with four hemiasterlin cytotoxins per antibody, enabling efficient tumor targeting while maintaining systemic stability. Ongoing studies include the REFRαME-O1 Phase 2/3 trial for platinum-resistant ovarian cancer and additional trials for endometrial cancer, non-small cell lung cancer, and combinations with bevacizumab for ovarian cancer. The company plans to start the REFRαME-P1 Phase 2/3 trial for CBF/GLIS2 acute myeloid leukemia, a rare pediatric cancer subtype, in the latter half of 2024. The U.S. FDA has granted luvelta Fast Track designation for ovarian cancer and Orphan and Rare Pediatric Disease designations for CBF/GLIS2 Pediatric AML.

Sutro Biopharma, headquartered in South San Francisco, is committed to developing precisely designed cancer therapeutics using its proprietary technology, aiming to improve patient outcomes and experience. Sutro’s innovative pipeline and strategic collaborations underscore its dedication to advancing oncological treatments.