On September 14, 2024 Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs), reported updated data from the ongoing Phase 1b study of luveltamab tazevibulin (luvelta) in combination with bevacizumab for patients with epithelial ovarian cancer (EOC) in a poster presentation at the 2024 European Society For Medical Oncology (ESMO) (Free ESMO Whitepaper) Congress in Barcelona, Spain (Press release, Sutro Biopharma, SEP 14, 2024, View Source [SID1234646623]).

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In this study, luvelta plus bevacizumab has demonstrated encouraging antitumor activity in patients with late-stage ovarian cancer irrespective of Folate Receptor-α (FRα) expression, including patients with no FRα expression, and prior bevacizumab treatment, with an overall response rate of 35%. These early data in combination may offer a non-biomarker driven approach to treat patients with EOC. The expansion phase of the study is ongoing at the recommended phase 2 dose (RP2D) of luvelta (4.3 mg/kg) in combination with bevacizumab (15 mg/kg) with an additional 23 patients enrolled to date; initial data is expected in the first half of 2025.

"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," said Jane Chung, Sutro’s President and Chief Operating Officer. "We have already seen promising antitumor activity with luvelta as a monotherapy treatment and we believe these combination data support our goal to deliver effective therapies to more patients living with cancer. We look forward to sharing initial results from our expansion phase in the first half of 2025."

ESMO Poster Presentation Highlights:

18 patients were enrolled; one patient remains on treatment.
Luvelta plus bevacizumab demonstrated encouraging antitumor activity in 17 RECIST evaluable patients:
At the RP2D (4.3 mg/kg), an Objective Response Rate (ORR) of 56% (5/9) was observed; no (0/6) patients had a response at 3.5 mg/kg and 50% (1/2) of patients had a response at 5.2 mg/kg.
An ORR of 35% (6/17) was observed in the overall population with a median duration of response of 9.3 months.
In patients with ≥25% FRα expression, an ORR of 44% (4/9) was observed; in patients with <25% FRα expression, an ORR of 29% (2/7) was observed.
No new safety signals were observed compared with either agent alone; consistent with previous reported luvelta safety results, the most common adverse event was neutropenia.
The Presentation will be accessible through the News & Events page of the Investor Relations section of the company’s website at www.sutrobio.com.

About Luveltamab Tazevibulin
Luveltamab tazevibulin, abbreviated as "luvelta" and formerly known as STRO-002, is a FRα-targeting antibody-drug conjugate (ADC) designed to treat a broad range of patients with ovarian cancer, including those with lower FRα-expression who are not eligible for approved treatment options targeting FRα. Developed and manufactured with Sutro’s cell-free XpressCF platform, luvelta is a homogeneous ADC with four hemiasterlin cytotoxins per antibody, precisely positioned to efficiently deliver to the tumor while ensuring systemic stability after dosing. REFRαME-O1, a Phase 2/3 registration-directed study for patients with platinum-resistant ovarian cancer is ongoing. The Company has additional ongoing trials in patients with endometrial cancer, non-small cell lung cancer, and in combination with bevacizumab in patients with ovarian cancer. The Company expects to initiate REFRαME-P1, a Phase 2/3 registration-directed study for patients with CBF/GLIS2 acute myeloid leukemia, a rare subtype of pediatric cancer, in the second half of 2024. The U.S. Food and Drug Administration (FDA) has granted luvelta a Fast Track designation for Ovarian Cancer, as well as Orphan and Rare Pediatric Disease designations for CBF/GLIS2 Pediatric AML.