FDA Grants Nuvation Bio's Mutant-IDH1 Inhibitor Safusidenib Fast Track Designation for IDH1-Mutant Glioma

A 27-patient Japanese study carried the filing

Nuvation Bio's release says the FDA based the decision on "favorable data from the safusidenib clinical program to date," and points to the J201 study in Japan. At a median follow-up of 38.8 months, the centrally assessed confirmed objective response rate in that 27-patient Phase 2 was 51.9% under the Response Assessment in Neuro-Oncology criteria for low-grade gliomas, median PFS had not been reached, the 36-month PFS rate was 79.1%, and only one prior responder had progressed. The company reported those figures July 20, 2026, as a one-year extension of results earlier published in Neuro-Oncology.

"People with IDH1-mutant glioma urgently need additional treatment options. We were eager to pursue Fast Track Designation for safusidenib to hopefully reach these patients on an expedited timeline," said David Hung, M.D., Nuvation Bio's founder, president and chief executive officer. Fast Track brings more frequent FDA interaction and, if the criteria are met, rolling review of a marketing application.

Three trials across the disease

SIGMA (G203) is enrolling roughly 300 patients with IDH1-mutant astrocytoma with high-risk features and compares safusidenib with placebo as maintenance after standard of care. An exploratory cohort of about 40 patients with grade 3 IDH1-mutant oligodendroglioma who have not had chemotherapy or radiotherapy runs alongside it, with objective response rate as the primary endpoint.

The two studies added in July widen the program at both ends. G307 is a randomized, placebo-controlled Phase 3 in about 140 newly diagnosed grade 2 patients, run outside the United States in regions where vorasidenib "is not yet approved or accessible," with blinded independent central review of PFS as the primary endpoint. G209 is a U.S. Phase 2 in up to 40 patients with grade 2 or 3 disease that has progressed after vorasidenib, with ORR by central review as its primary endpoint. Macarena de la Fuente, M.D., chief of the neuro-oncology division at Sylvester Comprehensive Cancer Center, said in the July release that "a critical question remains regarding sequencing of treatments once a patient progresses on a first-line inhibitor."

Testing language the release leaves open

The release defines the population by genotype throughout and cites a company estimate of nearly 2,500 U.S. IDH-mutant glioma diagnoses a year, more than 95% of them IDH1. It does not name the assay used to establish IDH1 status in J201 or SIGMA, and it says nothing about a companion diagnostic. Nuvation Bio acquired Japanese rights to safusidenib from Daiichi Sankyo in a deal announced April 1, 2026.

Why This Matters to the APO|APE Reader

Vorasidenib sits behind every one of these trials, as the drug absent from G307's regions and as the prior therapy in G209, so the safusidenib program will generate the first controlled data on an IDH1-mutant glioma after a first IDH inhibitor fails. SIGMA's design, maintenance after standard of care in high-risk astrocytoma, puts the IDH1 result in the pathology report ahead of eligibility, which means every adult diffuse glioma needs IDH1 status reported routinely. A Fast Track letter changes FDA meeting cadence, and the 300-patient enrollment clock in SIGMA decides when any of this reaches a label.