Henrique Orlandi Mourao
Micrograph showing AML Image from Paulo
The US Food and Drug Administration (FDA) has placed a clinical hold on both phase 1 studies of UCART123, a universal (allogeneic) chimeric antigen receptor (CAR) T-cell therapy targeting CD123.
One study was designed for patients with acute myeloid leukemia (AML), and the other was designed for patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN).
The clinical hold is due to the death of the first patient treated in the BPDCN trial.
The hold means no new subjects can be enrolled in either trial, and there can be no further dosing of subjects who are already enrolled.
BPDCN patient
The first patient treated in the BPDCN trial was a 78-year-old male who had received 1 prior therapy. He presented with relapsed/refractory BPDCN with 30% blasts in his bone marrow and cutaneous lesions (biopsy-proven BPDCN) at baseline.
The patient first received pre-conditioning with fludarabine (30 mg/m²/day for 4 days) and cyclophosphamide (1 g/m²/day for 3 days).
On August 16, 2017 (Day 0), the patient received UCART123 at 6.25 x 105 cells/kg, the first dose level explored in the protocol, without complication.
By Day 5, the patient had developed grade 2 cytokine release syndrome (CRS) and a grade 3 lung infection, which improved after a first dose of tocilizumab and the administration of broad-spectrum, intravenous antibiotics.
On Day 8, the patient was found to have more severe CRS (ultimately grade 5) and grade 4 capillary leak syndrome. Despite receiving treatment in keeping with CRS management, including the administration of corticosteroids and tociluzumab as well as intensive care unit support, the patient died on Day 9.
AML patient
The first patient treated in the AML study experienced similar adverse effects as the BPDCN patient but is still alive.
The AML patient was a 58-year-old woman with 84% blasts in her bone marrow at baseline.
On June 27, 2017 (Day 0), the patient received the same pre-conditioning regimen and the same dose of UCART123 as the BPDCN patient, without complication.
By Day 8, the AML patient had developed grade 2 CRS. This worsened to grade 3 on Day 9 and resolved on Day 11 with treatment in the intensive care unit.
The patient also experienced grade 4 capillary leak syndrome on Day 9 that resolved on Day 12.
Next steps
The data safety monitoring board for these trials met on August 28 and recommended lowering the dose of UCART123 to 6.25 x 104 cells/kg in both studies and capping cyclophosphamide to a total dose of 4 g over 3 days.
Cellectis, the company developing UCART123, said it is working with study investigators and the FDA to resume both trials with an amended protocol that includes these dose adjustments.
