To determine long-term efficacy of fremanezumab in patients with episodic or chronic migraine (EM/CM) considered inadequate responders after 3 months of double-blind (DB) treatment.

Fremanezumab, a fully-humanized monoclonal antibody (IgG2Δa) that selectively targets calcitonin gene-related peptide (CGRP), has demonstrated efficacy in migraine prevention. There is a need to understand how long migraine patients should be treated with medications such as fremanezumab and whether patients who do not respond early in the treatment cycle may respond if they remain on treatment longer.

During 3 months of DB treatment in the phase 3 HALO EM/CM studies (DBP), patients were randomized (1:1:1) to quarterly fremanezumab, monthly fremanezumab, or placebo. Patients completing treatment in HALO EM/CM and new patients entered the HALO long-term study (LTS), in which quarterly and monthly fremanezumab were maintained and newly enrolled and placebo patients were randomized 1:1 to quarterly or monthly fremanezumab. The subgroup with inadequate response was defined by <25% reduction in monthly migraine days (MDs) at 3 months (end of DBP), and subsequent response was evaluated by baseline category of MDs (<9; ≥9–≤12; ≥12–≤15; ≥15 days).

1,890 patients were enrolled in the LTS, with 210 characterized as inadequate responders. At months 6, 9, and 15 (end of LTS), respectively, for inadequate responders with <9 baseline MDs, a ≥50% reduction from baseline in monthly MDs (MRR) of 28%, 44%, and 50% and ≥50% reduction in headache days of at least moderate severity (HRR) of 50%, 47%, and 53% was shown. Similarly, in inadequate responders with ≥9–≤12, ≥12–≤15, and ≥15 baseline MDs, a ≥50% MRR was shown for 28%–49% of patients and ≥50% HRR for 42%–53% of patients at month 15.

These data show that patients with an inadequate initial response to fremanezumab may experience clinically meaningful reductions in migraine or headache days with continued treatment.