Bluebird’s sickle cell gene therapy gets hammered again

The main question stemming from the new partial FDA clinical hold on Lentiglobin is whether Bluebird’s planned filing for this sickle cell gene therapy is still on track for a year or so’s time. Bluebird has had to pause enrolment and treatment of patents under the age of 18 in three sickle cell trials owing to a case of persistent, non-transfusion-dependent anaemia in an adolescent treated with Lentiglobin 18 months ago. Although acute anaemia is common with stem cell transplants, Leerink analysts said the chronic nature of this case raised the spectre of malignancy; however, Bluebird said there was no evidence of this. Still, the group is only just recovering from a case of acute myeloid leukaemia in the HGB-206 trial, which prompted a clinical hold in February; Lentiglobin has since been exonerated, but another safety scare clearly does not sit well with investors, as Bluebird’s stock slid 20% today. Enrolment into the pivotal portion of HGB-206 is complete, but a filing, due in the first quarter of 2023, could be delayed if the latest hold hits the HGB-210 trial, testing commercial-grade product. Lentiglobin is already lagging Crispr/Vertex’s CTX001, and risks falling further behind.