During the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, Sutro Biopharma presented findings from a Phase I dose-expansion study of luveltamab tazevibulin (luvelta) in patients with advanced ovarian cancer.
Luveltamab tazevibulin, also known as luvelta or STRO-002, is an antibody-drug conjugate (ADC) that specifically targets the FolRα protein in ovarian cancer. It is designed to provide treatment options for a wide range of ovarian cancer patients, including those with lower levels of FolRα expression who are not eligible for currently approved treatments targeting FolRα. Luvelta is developed and manufactured using Sutro's cell-free XpressCF platform. This ADC consists of an antibody with four hemiasterlin cytotoxins attached, strategically positioned to effectively target the tumor while maintaining stability in the body.
In line with the data presented in January 2023, luvelta showed significant clinical advantages in patients selected based on their FolRα expression. These patients were identified using a Tumor Proportion Score (TPS) of >25%, regardless of the intensity of staining. This subgroup constitutes approximately 80% of the population of patients with advanced ovarian cancer.
When considering patients with a FolRα expression level exceeding 25% (Tumor Proportion Score, or TPS >25%, regardless of staining intensity), notable efficacy outcomes were observed. These included a 37.5% objective response rate (ORR), a median duration of response (DOR) of 5.5 months, and a median progression-free survival (PFS) of 6.1 months. Importantly, even higher response rates were achieved among patients receiving the higher starting dose of 5.2 mg/kg. These patients demonstrated a 43.8% ORR, a median DOR of 5.4 months, and a median PFS of 6.6 months. Notably, responses were observed in patients with FolRα expression (TPS >25%), offering a potential treatment option for individuals who may not qualify for other approved therapies targeting FolRα.
Additionally, the company is actively progressing with the clinical development of luvelta and has announced the initiation of enrollment in the REFRaME-O1 study. This pivotal Phase II/III trial aims to include patients with platinum-resistant ovarian cancer and marks a significant step forward in advancing the evaluation of luvelta as a potential treatment option for this patient population.
KOL insights
“I am encouraged by the preliminary efficacy, durability, and favorable safety profile observed in this study, which signify the potential of luveltamab tazevibulin as a promising therapeutic option for patients with ovarian cancer who are not well supported by current standard of care. The population of ovarian cancer patients that may benefit from treatment with luveltamab tazevibulin represents a significant unmet medical need globally” – Expert Opinion.
“Anti folate receptor alpha Antibody drug conjugate. Another new drug for ovarian cancer. Good clinical activity in recurrent ovarian cancer” – Expert Opinion.
Conclusion
The dose expansion data provide evidence of the effectiveness of luvelta at various starting doses (ranging from 4.3-5.2 mg/kg) in recurrent ovarian cancer patients with FolRα expression levels as low as TPS>25%. These findings support the need for further clinical investigation in this patient population. To that end, the global Phase II/III REFRaME registration study will assess the efficacy of luvelta specifically in patients with platinum-resistant ovarian cancer and a TPS>25%.
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