FDA places hold on Phase I testing of Cellectis' CAR T UCART123

Cellectis S.A. (Euronext:ALCLS; NASDAQ:CLLS) said a patient death prompted FDA to place a clinical hold on Phase I testing of its chimeric antigen receptor (CAR) T cell candidate UCART123. The company said it is discussing an amended protocol with FDA, which would include lowered dosing.

The Phase I ABC and AML123 trials were evaluating UCART123 in patients with relapsed or refractory blastic plasmacytoid dendritic cell neoplasm (BPDCN) and relapsed or refractory acute myelogenous leukemia (AML), respectively. The ABC trial’s first patient developed grade 5 cytokine release syndrome (CRS) and grade 4 capillary leak syndrome (CLS) after receiving a single IV infusion of 6.25x10⁵ UCART123 cells/kg following preconditioning with fludarabine and cyclophosphamide. The 78-year-old male subsequently died 9 days after UCART123 infusion despite treatment with corticosteroids and Actemra tocilizumab plus intensive care unit (ICU) support...