BioMarin vows to investigate cancer case in gene therapy trial, says studies are ongoing

Just a few weeks after BioMarin’s first-of-its-kind hemophilia A gene therapy Roctavian scored a conditional authorization in Europe, the company revealed that a patient in a phase 3 study of the treatment has been diagnosed with B-cell acute lymphoblastic leukemia. Based on BioMarin’s early assessment of the case, which includes genetic testing, the company believes that the cancer is “unrelated” to its therapy.

In a Securities and Exchange Commission filing, BioMarin noted that the overall rate of cancer diagnoses observed in the trial is two in approximately “400 patient years of observation,” which is “consistent with expected rates” of cancer in individuals with hemophilia. The company is conducting further testing to suss out whether the treatment had any role in the case.

Still, BioMarin updated international health authorities about the development earlier this month. No regulator has requested a trial hold, the company said.

All trials of the drug are ongoing, and the company “remains on track” to resubmit its biologics license application to the FDA by the end of the month, BioMarin added. Previously, the FDA postponed a decision on the medicine to seek further information from the company.

The September submission will push back a U.S. commercial launch until at least the first quarter of 2023, if it wins an FDA approval.

It's not the first time cancer has cropped up in a gene therapy trial. Last February, bluebird bio halted selling its blood disease gene therapy, Zynteglo, in Europe after two blood cancer cases turned up in a phase 1/2 sickle cell disease trial. That drug’s lentivirus vector was specifically designed to minimize the risk of causing cancer by integrating its own gene into the human genome. European regulators later found that the drug was not the cause of the cancer cases.

For BioMarin, it'll be crucial to determine whether Roctavian had anything to do with the cancer as soon as possible. The company believes the therapy will fill a “niche role” in the hemophilia A market, Evercore ISI analyst Josh Schimmer said in an August note to clients, noting that the drug has “blockbuster potential.”