FDA issues Complete Response Letter for Disc Medicine’s bitopertin
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.
Bitopertin
DrugDrug Profile
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.
- Drug Class
- Investigational orally administered glycine transporter 1 (GlyT1) inhibitor
- Approval Status
- Investigational and not approved in any jurisdiction worldwide; FDA issued CRL on February 13, 2026
- Mechanism of Action
- Inhibits GlyT1 to modulate heme biosynthesis in developing red blood cells
- \Erythropoietic protoporphyria (EPP)\
- \Erythropoietic porphyrias (investigational)\
Related News
FDA Rejects Accelerated Approval for Disc Medicine's Bitopertin for EPP
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 to Pursue Standard FDA Approval After Fast-Track Rejection for Bitopertin
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.
FDA Issues Complete Response Letter for Disc Medicine's Bitopertin in EPP
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.
FDA Issues Complete Response Letter for Disc Medicine's Bitopertin in EPP
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.
FDA Rejects Disc Medicine's Bitopertin for Rare Blood Disorder Under Fast-Track 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.
FDA Rejects Disc Medicine's Bitopertin Despite Fast-Track Review Under New Voucher Program
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.
FDA Denies Accelerated Approval for Bitopertin in EPP, Awaits Phase 3 Trial Results
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.
FDA Issues Complete Response Letter for Disc Medicine's Bitopertin in EPP Treatment
The FDA issued a Complete Response Letter for Disc Medicine's bitopertin New Drug Application for erythropoietic protoporphyria, requiring results from the ongoing Phase 3 APOLLO study before making an approval decision. Topline data is expected in Q4 2026.
Disc Medicine Receives FDA Complete Response Letter for Bitopertin EPP Treatment
Disc Medicine received a complete response letter from the FDA for bitopertin as a treatment for erythropoietic protoporphyria. The FDA acknowledged the drug lowers PPIX levels but requires evidence from the ongoing Phase 3 APOLLO study before approval.
Related Clinical Trials
| 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 |