Vistagen receives FDA Study May Proceed letter for refisolone IND

FDA issued a Study May Proceed letter under the refisolone IND, clearing the company to initiate further Phase 2 clinical development in the United States. The letter follows exploratory Phase 2a data from Mexico showing statistically significant reductions in hot-flash frequency and severity. This regulatory step enables U.S. Phase 2 advancement for the non-hormonal, intranasal pherine candidate.

Key facts

Filed: Apr 28, 2026, 08:13 PM
Event: Trial registry change
Direction: Positive
Company: VTGNVistagen Therapeutics, Inc.
Asset: refisolone
Source: SEC 8-K
Confidence: Sourced
p value: < .001
phase 2a N: 36
hot flash reduction placebo: 36%
hot flash reduction refisolone: 80%

Source excerpt

EX-99.1 2 vtgnpr20260422ex991.htm EX-99.1 Document Exhibit 99.1 Vistagen Receives FDA “Study May Proceed” Letter Under its Refisolone IND Application, Enabling Further Phase 2 Clinical Development for the Treatment of Vasomotor Symptoms (Hot Flashes) due to Menopause SOUTH SAN FRANCISCO, Calif. – April 22, 2026 – Vistagen (Nasdaq: VTGN) , a late clinical-stage biopharmaceutical company pioneering neuroscience with nose-to-brain neurocircuitry to develop and commercialize a new class of intranasal product candidates called pherines, today announced receipt of a “Study May Proceed” letter from the U.S. Food and Drug Administration (FDA) under its U.S. Investigational New Drug (IND) application for refisolone nasal spray, the Company’s non-hormonal, non-systemic product candidate in Phase 2 development for treatment of moderate to severe vasomotor symptoms (VMS) (also known as “hot flashes”) due to menopause. The FDA’s Study May Proceed letter enables the Company to pursue further Phase 2 clinical development of refisolone in the U.S. for a large unmet need in women’s health, building on successful exploratory Phase 2a clinical studies for the treatment of menopausal hot flashes and premenstrual dysphoric disorder conducted in Mexico. “This regulatory milestone marks another important step forward in our women’s health program for refisolone. Approximately 75% of all women in America experience hot flashes during their menopausal transition, yet there is a critical need for

SEC 8-K

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Apr 22, 2026

12:30 PM

VTGNVistagen Therapeutics, Inc.

Vistagen receives FDA Study May Proceed letter for refisolone IND

Trial registry changeCompany press release