Disc Medicine has received a complete response letter (CRL) from the US Food and Drug Administration (FDA) concerning its new drug application (NDA) for bitopertin for erythropoietic protoporphyria (EPP).
The submission sought accelerated approval and was part of the FDA Commissioner’s National Priority Voucher pilot programme.
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The CRL for bitopertin EPP affects the regulatory pathway and potential market entry.
The accelerated approval process required evidence of impact on a surrogate endpoint, the percentage change in whole blood metal-free protoporphyrin IX (PPIX), and whether this change is likely to predict clinical benefit.
The FDA acknowledged that the AURORA and BEACON studies demonstrated that bitopertin significantly reduces whole blood metal-free PPIX.
However, it concluded there was no demonstrated association between per cent change in PPIX and sunlight exposure-based endpoints, as measured in these studies, despite the biological plausibility of PPIX as a biomarker in protoporphyria.
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By GlobalDataThe agency indicated that results from the ongoing APOLLO trial could support traditional approval.
Disc expects issues raised by the FDA can be addressed through data from the APOLLO study, with topline data anticipated in the fourth quarter (Q4) of 2026.
The company intends to seek a Type A meeting with the FDA. In January, a blinded sample size re-estimation for APOLLO was performed and did not necessitate any adjustments. Enrolment is expected to be completed next month, ahead of schedule.
Upon completion, Disc plans to respond to the CRL and anticipates receiving a revised decision by mid-2027.
Disc president and CEO John Quisel said: “We are committed to delivering bitopertin to patients, knowing how critical this potentially disease-modifying therapy is to the EPP community. While our efforts at utilising expedited pathways to get bitopertin to patients quickly have not come to fruition, we are continuing to pursue all avenues in support of FDA approval.
“The CRL will delay the potential approval of bitopertin, but we have confidence in the ongoing APOLLO trial, for which we are seeing incredible enthusiasm from the EPP community. Confidence in our product and programme guides our approach, and we will continue working closely with the FDA to support their review.”
In January 2025, Disc raised $225.5m via an upsized public offering to support its pipeline, which included bitopertin.
