Hemogenyx Pharmaceuticals now knows what it will take to lift the clinical hold on its CAR-T cell therapy candidate. In its full review letter, the FDA cited a manufacturing issue as the cause of the hold, leading the biotech to identify the source of the problem and develop a solution.
London-based Hemogenyx filed to run a U.S. clinical trial of its HEMO-CAR-T candidate in May. The cell therapy is in development as a treatment for acute myeloid leukemia (AML). Getting the drug candidate, which is the biotech’s main focus, to the IND stage was (PDF) “more complex and hence longer and more intensive” than expected, but management believed it had minimized “any possible delays” to the filing.
That belief proved optimistic. Weeks after disclosing the IND filing, Hemogenyx revealed that the FDA had imposed a clinical hold on the planned early-phase trial of HEMO-CAR-T. The biotech lacked a full picture of the problem when it first disclosed the hold early last month.
Now, Hemogenyx has the full review letter from the FDA and has provided an update on the next steps. The FDA put the study on hold over “a splicing that occurs during the manufacturing process of the lentivirus that is used to produce CAR-T cells,” according to Hemogenyx. In response, the biotech has found the source of the splicing deficiency and developed a method to mitigate the problem.
Hemogenyx is now remanufacturing lentivirus, the vectors used in the production of HEMO-CAR-T. The biotech partnered with WuXi Advanced Therapies on the production of lentiviral vectors in 2021. While the FDA review “contains several suggestions on how to improve the safety of HEMO-CAR-T,” the biotech said they didn’t contribute to the clinical hold and “can be dealt with readily.”
The comment suggests Hemogenyx will get out from under the hold once the lentivirus issue is resolved. Shares in Hemogenyx initially climbed in the wake of the publication of the update, only to later give up most of the gains. The stock remains well down on the price it commanded before the biotech informed investors of the clinical hold at the start of last month.
Hemogenyx’s statement and other materials lack details of the target of HEMO-CAR-T. The biotech filed for a patent titled “Anti-FLT3 Antibodies, CARs, CAR T Cells and Methods of Use” last year. FLT3, a focus of Hemogenyx’s bispecific work, is implicated in AML.