FDA Grants Fast Track Designation to Safusidenib for IDH1-Mutant Glioma

The FDA has granted Fast Track Designation to safusidenib, an investigational oral, brain-penetrant selective inhibitor of mutant IDH1, for the treatment of patients with IDH1-mutant glioma, according to developer Nuvation Bio.¹ The designation comes as the agent advances into a pivotal phase 3 program.

For patients with IDH1-mutant gliomas, the designation represents an encouraging step toward therapies designed around the underlying biology of their tumors, according to Katy Peters, MD, PhD, FAAN, professor of neurology at Duke University in North Carolina. Fast Track Designation facilitates more frequent communication between the FDA and drug developers during clinical development and, when applicable criteria are met, can allow for rolling review of portions of a marketing application.

“This FDA Fast Track Designation is just very encouraging because it truly recognizes that [safusidenib] is a drug that has potential to meet a really critical unmet need for patients with IDH1-mutant glioma,” Peters said in an interview with NeurologyLive^®.

IDH1-mutant gliomas comprise a heterogeneous group of brain tumors. Although patients with IDH1-mutant disease generally have longer survival than those with IDH wild-type tumors, the disease remains incurable, and prognosis can worsen among patients with higher-risk features, including high-grade tumors.

Updated Data Show Durable Responses

The Fast Track designation follows updated long-term findings from the phase 2 J201 (NCT04458272) study of safusidenib in patients with chemotherapy- and radiotherapy-naïve grade 2 IDH1-mutant glioma.

As previously reported, at a median follow-up of 38.8 months, data from 27 patients in Japan showed a centrally assessed confirmed objective response rate (ORR) of 51.9%, based on Response Assessment in Neuro-Oncology (RANO) criteria for low-grade gliomas. Overall, median progression-free survival (PFS) had not been reached, while the 36-month PFS rate was 79.1%.²

The data showed that responses were durable, with only 1 patient who had previously responded subsequently experiencing disease progression. Notably, no new safety signals were identified with longer follow-up.

In the interview, Peters highlighted the durability of disease control seen in the study as particularly encouraging, noting that PFS can serve as an important measure when considering longer-term outcomes for patients with glioma.

“What was really interesting is that when we look at progression-free survival as a marker for even long-term survival, that median progression-free survival had not been reached,” Peters said.

The findings were particularly relevant in lower-grade IDH1-mutant glioma, where patients can live for years with their disease and may face the long-term consequences of radiation and chemotherapy. Determining whether targeted therapy can control disease while delaying or reducing exposure to these treatments remains an important area of investigation.

“These patients are in their 30s to 40s to 50s; they have jobs, they have families, things are happening,” Peters explained. “What can we delay [in terms of] radiation and chemotherapy effectively and mitigate the side effects?”

Safusidenib Moves Into Phase 3 Development

Nuvation is evaluating safusidenib in several clinical settings designed to determine where IDH1 inhibition may provide the greatest benefit. The phase 3 SIGMA (G203; NCT05303519) study is evaluating safusidenib vs placebo as maintenance therapy following standard-of-care treatment in patients with IDH1-mutant astrocytoma with high-risk features. The pivotal portion of the study is expected to enroll approximately 300 patients.¹

A separate exploratory, nonpivotal cohort is evaluating safusidenib in patients with grade 3 IDH1-mutant oligodendroglioma who have not previously received chemotherapy or radiotherapy. This cohort is expected to enroll approximately 40 patients, with objective response rate serving as the primary endpoint.

The broader development program also includes the phase 3 G307 study outside the United States, which is evaluating safusidenib in approximately 140 patients with newly diagnosed grade 2 IDH1-mutant glioma who have not received chemotherapy or radiation. The study is being conducted in regions where vorasidenib is not yet approved or accessible.¹

In the United States, the phase 2 G209 study is evaluating safusidenib in up to 40 patients with grade 2 or 3 IDH1-mutant glioma whose disease has progressed following treatment with vorasidenib. The study is intended to address an important question surrounding the sequencing of targeted therapies after progression on an initial IDH inhibitor.

Defining the Role of Targeted Therapy

For clinicians, Peters emphasized that safusidenib remains investigational, but the ongoing studies could help define how targeted IDH1 inhibition fits into the treatment sequence for patients with these tumors. She also pointed to the importance of clinical trial participation as investigators work to determine which patients are most likely to respond and how safusidenib could be incorporated alongside other treatments.

“I think that clinicians need to think about this as an option for their patients, because many of these clinical trials are open,” Peters said. “We need research to keep moving this forward.”

Additional questions include whether targeted treatment can safely delay radiation and chemotherapy, how safusidenib should be sequenced with other therapeutics, and whether improvements in PFS ultimately translate into longer overall survival and preservation of cognitive function.

“If we got [safusidenib] approved as a monotherapy, we have an option that is specific to those patients by virtue of the fact that they have that IDH1 mutation,” Peters said. “The next is, if patients do have to have other therapeutics, how would we combine them appropriately?”

Ultimately, Peters said, answering those questions will require continued collaboration across neuro-oncology, radiation oncology, neurosurgery and neuropsychology, with clinical trials designed to assess not only tumor control but also the long-term effects of treatment.

“We're really excited that we can actually use the biology of these tumors to improve outcomes in our patients and to give them drugs that are specific to them and that are tolerable,” Peters said.

REFERENCES
1. Nuvation Bio Granted FDA Fast Track Designation for Safusidenib for Treatment of IDH1-Mutant Glioma. Nuvation Bio. News Release. August 20, 2026. Accessed: August 21, 2026.https://investors.nuvationbio.com/news/news-details/2026/Nuvation-Bio-Granted-FDA-Fast-Track-Designation-for-Safusidenib-for-Treatment-of-IDH1-Mutant-Glioma/default.aspx
2. Nuvation Bio Announces Positive Updated Phase 2 Data and Expansion of Safusidenib Clinical Program with Two New Studies to Explore Broad Spectrum of IDH1-Mutant Glioma. Nuvation Bio. News Release. July 20, 2026. Accessed: August 24, 2026. https://investors.nuvationbio.com/news/news-details/2026/Nuvation-Bio-Announces-Positive-Updated-Phase-2-Data-and-Expansion-of-Safusidenib-Clinical-Program-with-Two-New-Studies-to-Explore-Broad-Spectrum-of-IDH1-Mutant-Glioma/default.aspx