Chromosomal "Abnormality" Forces Allogene to Halt Trial as Shares Crater

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Allogene Therapeutics today announced that it is halting the clinical trial for its AlloCAR T cancer therapy after finding some chromosomal abnormality in a patient. 

The clinical-stage biotechnology firm placed its study on hold after sending a notification to the U.S. Food and Drug Administration about a chromosomal abnormality in its ALPHA2 study patient. Allogene has dosed over 100 patients with its gene-edited AlloCAR T products. The firm believes that the ALPHA trials' findings support a favorable clinical profile for ALLO-501A in patients diagnosed with large B cell lymphoma. 

The problem was found after taking a bone marrow biopsy to assess the patient for pancytopenia (low blood count). Allogene is investigating the issue to characterize the observation, including any clinical relevance, potential relationship to gene editing or evidence of clonal expansion. 

The case in question involves a patient diagnosed with Stage IV transformed follicular lymphoma and c-myc rearrangement whose cancer did not respond to two prior lines of immune chemotherapy and additional radiation therapy. 

When ALLO-501A was infused, the patient experienced Grade 1 CRS and Grade 2 ICANS, which then required a high dose steroid therapy. The patient later developed progressive pancytopenia, and scientists found aplastic anemia and the presence of ALLO-501A CAR T cells with the chromosomal abnormality after a bone marrow biopsy was taken. The CAR T cells were found to have expanded and peaked on Day 28 and then later contracted. 

"Patient safety is our highest priority, and we are committed to working closely with the FDA to evaluate any potential clinical implications of this finding, and determine next steps for advancing ALLO-501A and our clinical programs. As a leading developer of allogeneic cell therapies, we recognize our added responsibility to fully assess all aspects of our therapies to advance the field," said Rafael Amado, M.D., executive vice president of research and development and chief medical officer of Allogene Therapeutics, in a statement

"We are grateful for the partnership with the patient community, clinical investigators, our Scientific Advisory Board, and the FDA as we work diligently toward understanding the clinical significance of this finding and to support the development of allogeneic CAR T therapy for cancer," added Dr. Amado.

The news sent Allogene's shares down by as much as 40% at the close of the market Thursday.

More updates are expected to be released in the coming weeks after the company meets with the FDA for its recommendations. The regulator actively reviews the end of Phase I materials submitted in preparation for an ALLO-501A Phase II trial.

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