Bitopertin is an investigational oral GlyT1 inhibitor being developed for erythropoietic porphyrias, including erythropoietic protoporphyria. It aims to modulate heme biosynthesis through glycine transport control in developing red blood cells. As of February 13, 2026, FDA issued a Complete Response Letter for the NDA, and the therapy remained unapproved globally.
Disc Medicine received an FDA Complete Response Letter for bitopertin over PPIX. It plans to complete APOLLO enrollment by March 2026, with topline data in Q4 2026 and a decision targeted by mid-2027.
Disc Medicine has agreed with the FDA to resubmit bitopertin for rare blood disorder erythropoietic protoporphyria, with the agency allowing the Phase 3 APOLLO trial to support a new filing. The agreement follows a February rejection and could lead to a mid-2027 decision. Disc has implemented workforce cuts and its CFO sold shares amid the regulatory setback.
The FDA issued a Complete Response Letter for Disc Medicine’s bitopertin NDA in EPP, saying additional evidence is needed. The agency wants Phase 3 APOLLO data before deciding.
The FDA rejected accelerated approval for Disc Medicine's bitopertin for erythropoietic protoporphyria, citing insufficient evidence that biomarker reductions translate to clinical benefit. The agency wants to see results from the ongoing Phase 3 APOLLO trial before considering traditional approval, pushing any decision to at least mid-2027. Disc Medicine plans to address FDA concerns with APOLLO data expected in Q4 2026.
Disc Medicine will pursue traditional U.S. approval for bitopertin after the FDA declined to approve the rare disease drug under an accelerated review pathway, with a potential decision expected around mid-2027.
Disc Medicine received a complete response letter from the FDA for bitopertin in erythropoietic protoporphyria, with the agency requesting Phase 3 APOLLO trial results before approval. The company expects to respond by mid-2027.
The FDA issued a Complete Response Letter for Disc Medicine's bitopertin application for erythropoietic protoporphyria, citing concerns over surrogate endpoints despite review under the accelerated approval pathway and Commissioner's National Priority Voucher pilot program.
The FDA declined to approve Disc Medicine's bitopertin for erythropoietic protoporphyria on February 13, 2026, citing insufficient evidence linking biomarker reductions to clinical benefit. The company will pursue traditional approval using Phase 3 APOLLO trial data expected in Q4 2026.
The FDA rejected Disc Medicine's bitopertin for erythropoietic protoporphyria, citing uncertainties about clinical benefit despite the drug receiving a priority review voucher. The company will pursue traditional approval with Phase 3 data expected in late 2026.
The FDA issued a Complete Response Letter for bitopertin in erythropoietic protoporphyria, acknowledging the drug lowers PPIX levels but requiring Phase 3 APOLLO trial results to demonstrate clinical benefit before approval.
| NCT ID | Title | Status | Phase |
|---|---|---|---|
| NCT07123363 |
Effect of Bitopertin on the Liver and on Levels of Protoporphyrin IX in Bile, Blood, Liver, and Stool in Patients With Erythropoietic Protoporphyria/X-linked Protoporphyria and Increased Liver Stiffness and/or Liver Enzymes at Baseline |
WITHDRAWN | PHASE1 |
| NCT05828108 |
Study of the Selective GlyT1 Inhibitor Bitopertin for Steroid-Refractory Diamond-Blackfan Anemia |
COMPLETED | PHASE1/PHASE2 |
| NCT03271541 |
A Study of Bitopertin (RO4917838) in Adults With Non-Transfusion-Dependent (NTD) Beta-Thalassemia |
COMPLETED | PHASE2 |
| NCT02019290 |
A Study Exmining the Effect of Multiple Doses of Bitopertin on the Single Dose Pharmacokinetics of Midazolam in Healthy Volunteers. |
WITHDRAWN | PHASE1 |
| NCT01674361 |
A Study of Bitopertin (RO4917838) in Combination With Selective Serotonin Reuptake Inhibitors (SSRIs) in Participants With Obsessive-Compulsive Disorder (OCD) |
COMPLETED | PHASE2 |
| NCT01636492 |
A Study of Bitopertin (RO4917838) in Healthy Male Volunteers |
COMPLETED | PHASE1 |
| NCT01192880 |
A Study to Evaluate Efficacy and Safety of Bitopertin in Participants With Persistent, Predominant Negative Symptoms of Schizophrenia |
COMPLETED | PHASE3 |
