FDA Clinical Hold of AlloCAR T Trials

Allogene Therapeutics Reports FDA Clinical Hold of AlloCAR T Trials Based on a Single Patient Case in ALPHA2 Trial.

The clinical hold follows the Company’s notification to the FDA of a chromosomal abnormality in an ALPHA2 study patient which was detected in a bone marrow biopsy undertaken to assess pancytopenia (low blood counts). An investigation is underway to further characterize the observed abnormality, including any clinical relevance, evidence of clonal expansion, or potential relationship to gene editing.

The single case involves a patient with Stage IV transformed follicular lymphoma and c-myc rearrangement whose cancer was refractory to two prior lines of immune-chemotherapy and additional radiation therapy. The patient could not receive an autologous CD19 CAR T cell therapy due to manufacturing failure associated with inadequate expansion of autologous CAR T cells.

Following infusion of ALLO-501A, the patient experienced Grade 1 CRS and Grade 2 ICANS, which required a course of high dose steroid therapy. The patient subsequently developed progressive pancytopenia and a bone marrow biopsy showed aplastic anemia and the presence of ALLO-501A CAR T cells with the chromosomal abnormality. Early translational data showed that the CAR T cells expanded, peaking on Day 28, and undergoing contraction thereafter. The patient had a partial response to ALLO-501A and subsequently underwent allogeneic stem cell transplantation. Prolonged cytopenia requiring rescue stem cell transplantation has been reported in autologous CAR T therapies.

Allogene has dosed more than 100 patients with its gene edited AlloCAR T products. The Company believes the data generated from the ALPHA trials support a favorable clinical profile for ALLO-501A in patients with large B cell lymphoma.