Disc Medicine's bitopertin clears all APOLLO endpoints, with 41.4% PPIX reduction vs. placebo

Disc Medicine said its Phase 3 APOLLO trial of bitopertin met both co-primary endpoints and every secondary endpoint in adults and adolescents with erythropoietic protoporphyria, reporting a 41.4% reduction from baseline in whole-blood metal-free PPIX versus placebo and a 12.2-hour gain in pain-free time in light during month 6. The company plans to resubmit a new drug application to the U.S. Food and Drug Administration by the end of 2026, with a decision anticipated by mid-2027.

The October 19, 2026 filing is not a quarterly earnings report. Disc Medicine's Form 8-K carries Items 7.01, 8.01 and 9.01 and attaches a press release and a topline-results deck; nothing in it reports revenue, expenses, a cash balance or a net loss for the three months ended September 30, 2026. What it carries is the first topline readout from APOLLO, a randomized, double-blind, placebo-controlled Phase 3 trial that enrolled 183 patients aged 12 or older in the United States, Canada, Europe and Australia and assigned them 1:1 to 60 mg of oral bitopertin or placebo once daily for six months.

APOLLO clears both co-primary endpoints

The two prespecified primary measures both favored the drug. The reduction from baseline in whole-blood metal-free PPIX, the photoactive intermediate that accumulates in EPP, was 41.4% versus placebo (p<0.0001). Average monthly total time in light without pain during month 6 increased 12.2 hours versus placebo (p=0.0010). Bitopertin is designed to inhibit glycine transporter 1, a protein on developing red blood cells that supplies glycine for heme biosynthesis; less heme synthesis means less PPIX to accumulate. Disc licensed global rights to the molecule from Roche in May 2021, and it is approved in no jurisdiction.

“Today represents a potential breakthrough in the science and treatment of EPP,” Chief Executive John Quisel said in the release. He added that “We could not have hoped for a better outcome”.

Phototoxic reactions 71% lower than placebo, and a 56-minute prodrome gain

On the secondary endpoints, the incidence rate of phototoxic reactions was 71% lower than on placebo across the six-month treatment period (IRR of 0.29, p<0.0001). Cumulative time in light without pain also improved (p<0.0001), as did the change from baseline in average daily sunlight exposure time to prodrome, by 56 minutes (p=0.0077, adults only). The release does not print absolute PPIX concentrations, confidence intervals or the size of the cumulative-time gain, and the deck shows several of those results only as charts, so the depth of benefit beyond the co-primary numbers cannot be reconstructed from the filing.

The release places the quality-of-life measures in a separate, exploratory category: Patient Global Impression of Change and Patient Global Impression of Severity scores each reached p<0.0001 versus placebo.

Dizziness in half the bitopertin arm, but no discontinuations

Any treatment-emergent adverse event was reported in 77 bitopertin patients (85%) and 69 placebo patients (75%). Dizziness was the most common event in the bitopertin group: 45 of 91 patients (50%), against 10 of 92 (11%) on placebo, and the release describes it as mild or moderate and generally transient. Headache was less frequent on bitopertin (15 patients, 17%) than on placebo (19, 21%). Six bitopertin patients (7%) had a Grade 3 event against three (3%) on placebo, serious adverse events were one (1%) against two (2%), and no bitopertin patient discontinued for any reason. No event above Grade 3 was reported, and the company says the molecule has been studied in more than 4,000 clinical trial participants across its development history.

A resubmission by end-2026, and a decision expected mid-2027

Disc calls its next regulatory step a resubmission, which implies an earlier application; the release does not describe what happened to that submission or what changed in it. The stated plan is to refile with the FDA by the end of 2026, with a decision anticipated by mid-2027, and to present detailed data at an upcoming medical conference. The commercial backdrop is a U.S. EPP addressable market the deck sizes at $2B+ and a single approved competitor, Scenesse (afamelanotide), a surgically implanted synthetic hormone that stimulates melanin production. Management discusses the results on a webcast at 8:00 a.m. ET today; no quarterly financials have been filed with this release. The deck's commercial section carries a launch target of November 2026, which sits awkwardly beside the mid-2027 decision date the release anticipates.