Material Event (Form 8-K)

Item 8.01. Other Events

On March 9, 2026, Trevi Therapeutics, Inc., a Delaware corporation (the "Company"), announced results of the Company's End-of-Phase 2 meeting with the U.S. Food and Drug Administration (the "FDA"). At the meeting, the Company gained overall alignment on the plan for the remaining idiopathic pulmonary fibrosis ("IPF")-related chronic cough development program. The Company plans to conduct two pivotal Phase 3 clinical trials and obtained agreement on the remaining Phase 1 clinical studies that the Company expects to conduct to support the New Drug Application ("NDA") submission. The Company plans to conduct the Phase 3 trials in parallel with each other and is on track to initiate the first Phase 3 trial in the second quarter of 2026 and the second Phase 3 trial in the second half of 2026.

The Phase 3 trials will both be randomized, double-blind, placebo-controlled, multicenter, global trials evaluating the safety and efficacy of nalbuphine ER tablets, with 54 mg twice-a-day ("BID") dosing, for the treatment of patients with IPF-related chronic cough. Patients enrolled in the trials will be randomized 2:1 to either nalbuphine ER or placebo. The first of the two Phase 3 trials is planned to enroll approximately 300 patients with IPF-related chronic cough and have 52 weeks of fixed dosing, with the primary endpoint at 24 weeks of fixed dosing. The other Phase 3 trial is planned to enroll approximately 130 patients with IPF-related chronic cough and have 12 weeks of fixed dosing. The primary efficacy endpoint for both trials will be the relative change from Baseline in 24-hour cough frequency (coughs per hour), as determined by an objective cough monitor, for nalbuphine ER compared with placebo. These trial designs are subject to final review of the protocols by the FDA.