BioMarin will proceed with phase 3 study of the investigational gene therapy BMN 270 (valoctocogene roxaparvovec) for the treatment of adults with severe hemophilia A despite a participant being diagnosed with B-cell acute lymphoblastic leukemia (B-ALL). The diagnosis was confirmed approximately 3 years after the participant received the dose of BMN 270.

Early assessment of the case by a committee of experts did not find evidence for the involvement of BMN 270 in the development of cancer in this participant. The evaluation committee was composed of the BioMarin study team, the study investigator, the independent data safety monitoring committee, as well as other medical and scientific experts.

“This initial finding is based on test results for this participant which were consistent with findings typically seen in patients who are diagnosed with B-ALL. In addition, tests of the participant’s leukemic cells for genetic material (DNA) from BMN 270 showed that it was found in extremely low levels,” BioMarin wrote in an update to the hemophilia community.

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The patient is still enrolled in the BMN 270 trial while receiving standard-of-care treatment for ALL. BioMarin plans to follow his health for 5 years after the initial treatment and for an additional period of 10 years in a long-term follow-up study.

According to the company, the overall rate of cancer diagnoses observed in the BMN 270 trial is consistent with expected rates of cancer in persons with hemophilia.

BioMarin recommended that patients speak with their physicians about any questions regarding gene therapy.

“BioMarin supports the shared decision-making framework to enable a personalized dialogue between an individual patient, his physician and care team and we remain committed to informing & educating physicians, patients, advocacy groups & the hemophilia community as we learn more about this case,” the statement reads.


Update for the hemophilia community. BioMarin. September 12, 2022. Accessed September 26, 2022.