FDA initiates clinical hold on Cellectis’ UCART123 trials


The US Food and Drug Administration (FDA) has initiated a clinical hold on Phase I trials of biopharmaceutical firm Cellectis’ universal chimeric antingen receptor T-cells (UCARTs) product candidate UCART123.

UCART123 is a gene-edited T-cell investigational drug designed to target CD123 antigen that is expressed on the surface of various leukaemic and tumoural cells.

The hold includes trials for acute myeloid leukaemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN), and was imposed following the report of fatality of a 78-year-old male in the BPDCN trial.

The patient received one previous therapy and had relapsed / refractory BPDCN with 30% blasts in bone marrow and cutaneous lesions at baseline before conditioning regimen, while his preconditioning regimen was 30mg/m²/day fludarabine for four days and 1g/m²/day of cyclophosphamide for three days.

"UCART123 is a gene-edited T-cell investigational drug designed to target CD123 antigen that is expressed on the surface of various leukaemic and tumoural cells."

Upon administration of 6.255 x 105 UCART123 cells per kilogramme at day zero, the patient is reported to have experienced a grade 2 cytokine release syndrome (CRS) and a grade three lung infection at day five.

The infections are said to have improved following the first dose of tocilizumab and institution of anti-infective therapy, while at day eight he had a grade four CRS and a grade four capillary leak syndrome, and died on day nine.

In the AML trial, a 58-year-old woman with 84% blasts received the same regimen without complication.

After a meeting on 28 August, the Data Safety Monitoring Board (DSMB) has recommended the firm to decrease the UCART123 dose to 6.254/kg x 104/kg in both the trials.


Image: Human cells with acute myelocytic leukaemia. Photo: courtesy of Dr Lance Liotta Laboratory.