Vincerx Pharma announces two complete responses in VIP943 study

Vincerx Pharma announced two complete responses in the ongoing first-in-human, Phase 1 dose-escalation study of VIP943, the company’s next-generation antibody-drug conjugate, or ADC, being evaluated in relapsed/refractory acute myeloid leukemia, or AML, higher-risk myelodysplastic syndrome, or HR-MDS, and B-cell acute lymphoblastic leukemia, or B-ALL. The company also provided pipeline and corporate updates. The ongoing Phase 1 dose-escalation study of VIP943 has enrolled 22 patients to date across several escalating dose cohorts. These 22 patients represent a ‘hard-to-treat’ salvage population, which rarely responds to monotherapy. Nine patients have received at least three doses of an efficacious dose of VIP943. Of these nine patients, four remain on study. So far, one patient with relapsed AML has achieved complete remission with incomplete hematologic improvement and one patient with HR-MDS has achieved complete remission with limited count recovery based on international consensus response criteria. These response criteria are widely recognized as an approvable benchmark in AML and MDS studies, further underscoring the significance of these early results. As of August, VIP943 has shown favorable safety and tolerability, with no dose-limiting toxicities reported in 22 patients. Serious adverse events, or SAEs, have been consistent with expectations for this patient population. The most common SAEs included pneumonia and cellulitis and febrile neutropenia. Only one patient experienced a drug-related SAE. Target engagement has been demonstrated by binding of VIP943 to CD123+ peripheral blood blasts from patients with AML from the Phase 1 study. Maximal receptor occupancy of 84% was achieved in the highest dose cohort. Across all the cohorts, receptor occupancy was retained for less than 96 hours. Concurrent decreases in CD123+ peripheral blood blasts were also observed after dosing. These pharmacodynamic markers show that VIP943 is binding to and eliminating CD123+ malignant cells. Preliminary pharmacokinetic data continues to show low release of payload. The half-life of VIP943 is less than 96 hours, and no accumulation occurs with repeat dosing. These PK and PD results have prompted evaluation of twice weekly dosing of VIP943 as a potential “induction” regimen. Enrollment in the once weekly and twice weekly dosing cohorts is ongoing. The company anticipates providing another data update on the ongoing Phase 1 VIP943 study by the end of the year.