Background: Intranasal formulations can provide treatment options for people with migraine in whom oral drugs are ineffective, slow-acting, or intolerable because of nausea and vomiting. Zavegepant, an intranasally administered small molecule calcitonin gene-related peptide (CGRP) receptor antagonist, was previously assessed in a phase 2/3 trial. This phase 3 trial aimed to compare the efficacy, tolerability, safety, and timecourse of response for zavegepant nasal spray with placebo in the acute treatment of migraine.

Methods: This double-blind, randomised, placebo-controlled, multicentre phase 3 trial, conducted at 90 academic medical centres, headache clinics, and independent research facilities in the USA, recruited adults (aged ≥18 years) with a history of two to eight moderate or severe migraine attacks per month. Participants were randomly assigned (1:1) to zavegepant 10 mg nasal spray or matching placebo and self-treated a single migraine attack of moderate or severe pain intensity. Randomisation was stratified by the use or non-use of preventive medication. Study centre personnel entered eligible participants into the study using an interactive web response system that was operated and managed by an independent contract research organisation. All participants, investigators, and the funder were masked to group assignment. The coprimary endpoints, freedom from pain and freedom from the most bothersome symptom at 2 h after the treatment dose, were assessed in all randomly assigned participants who took the study medication, had a migraine attack of moderate or severe pain intensity at baseline, and provided at least one evaluable post-baseline efficacy datapoint. Safety was analysed in all randomly assigned participants who received at least one dose. The study is registered with ClinicalTrials.gov, number NCT04571060, and is closed to accrual.

Findings: Between Oct 27, 2020, and Aug 20, 2021, 1978 participants were recruited and assessed for eligibility. 1405 participants were eligible (703 were assigned to zavegepant and 702 to placebo), and 1269 were included in the efficacy analysis set (623 in the zavegepant group and 646 in the placebo group). 2 h after the treatment dose, more participants in the zavegepant group than in the placebo group had pain freedom (147 [24%] of 623 participants vs 96 [15%] of 646 participants, risk difference 8·8 percentage points, 95% CI 4·5-13·1; p<0·0001) and freedom from their most bothersome symptom (247 [40%] vs 201 [31%], risk difference 8·7 percentage points, 3·4-13·9; p=0·0012). The most common adverse events in either treatment group (≥2%) were dysgeusia (129 [21%] of 629 in the zavegepant group vs 31 [5%] of 653 in the placebo group), nasal discomfort (23 [4%] vs five [1%]), and nausea (20 [3%] vs seven [1%]). No signal of hepatotoxicity due to zavegepant was identified.

Interpretation: Zavegepant 10 mg nasal spray was efficacious in the acute treatment of migraine, with favourable tolerability and safety profiles. Additional trials are needed to establish the long-term safety and consistency of effect across attacks.

Funding: Biohaven Pharmaceuticals.