Sutro announces data on anti-leukemic activity from luvelta compassionate use

Sutro Biopharma announced that its research collaborators presented data on anti-leukemic activity from the compassionate use of luveltamab tazevibulin, or luvelta, a folate receptor-alpha targeting ADC, in pediatric patients with relapsed/refractory CBFA2T3-GLIS2 acute myeloid leukemia, or AML, commonly known as RAM phenotype AML. Data demonstrated that treatment with luvelta produced meaningful clinical responses, including complete remission, or CR; and prolongs overall survival, or OS, enabling some patients to receive potentially curative therapies such as hematopoietic stem cell transplant. These patients were treated under the single patient IND mechanism. These data were featured in a poster presentation at the 65th American Society of Hematology Annual Meeting and Exposition, or ASH 2023, in San Diego, California. Under compassionate use, 25 pediatric patients with relapsed/refractory CBF/GLIS subtype AML were treated with luvelta at doses up to 4.3 or 5.2mg/kg every two to four weeks for a median duration of 15.9 weeks, with the majority of patients receiving at least five doses. Of the 25 treated patients, 19 had greater than or equal to 5% blasts and 8 had less than 5% blasts. Collective results show that treatment with luvelta produced clinically meaningful and durable responses across a broad range of patients in various settings including in patients with or without prior stem cell transplant and in monotherapy or in combination with cytotoxic therapy. These data were generated by the treating physicians and collected and enabled for presentation by Sutro. Overall, anti-leukemic activity was seen with luvelta either as a single agent or in combination. Overall, 19 patients had greater than or equal to 5% blasts and 8 patients had less than5% blasts. A CR/CRh was observed in 8 out of 19 patients with greater than or equal to 5% blasts treated with luvelta, with 5 out of 8 CR/CRh patients reaching a minimal residual disease, or MRD-negative CR. In total, 6 out of 8 patients with less than5% blasts experienced an MRD-negative CR. Patients whose leukemia experienced an MRD-negative CR had an improved outcome over those who did not experience an MRD-negative CR. Treatment with luvelta also enabled some children to bridge to stem cell transplant, which is potentially curative therapy. Luvelta was well-tolerated as a monotherapy agent and in combination with standard of care therapies with minimal hematopoietic toxicity and can be delivered as outpatient therapy. As of September 17, 8 patients remain on treatment, with 5 of the 8 in continued remission and on luvelta maintenance.