Changes in migraine interictal burden following treatment with galcanezumab: Results from a phase III randomized, placebo-controlled study

Objective: To evaluate changes in interictal burden with galcanezumab versus placebo in patients with episodic (EM) or chronic migraine (CM). Background: The disruptive effects of migraine occur both during attacks (ictal period) and between attacks (interictal period), affecting work, school, family, and social life. Migraine clinical trials typically assess ictal burden endpoints, neglecting interictal burden. Methods: CONQUER was a 3-month, double-blind study that randomized adult patients with EM or CM who had experienced failure of two to four standard-of-care migraine preventive medication categories to receive monthly galcanezumab (n = 232) or placebo (n = 230), followed by 3 months of open-label galcanezumab. The mean change in interictal burden, a secondary objective, was measured using the four-item Migraine Interictal Burden Scale (MIBS-4). The total score for MIBS-4 can range from zero to 12, with scores ≥5 indicating severe interictal burden. Post hoc analyses evaluated shifts in MIBS-4 severity categories and item-level improvement. Results: The MIBS-4 total score indicated severe interictal burden at baseline (mean [SD]: all patients, 5.5 [3.5]; EM, 5.0 [3.4]; CM, 6.2 [3.5]). Reductions in the MIBS-4 score were significantly greater with galcanezumab versus placebo at Month 3 (mean [SE]: all patients −1.9 [0.2] vs. −0.8 [0.2], p < 0.0001; EM, −1.8 [0.3] vs. −1.1 [0.3], p = 0.033; CM, −1.8 [0.4] vs. −0.3 [0.4], p < 0.001), with further improvement at Month 6 after all patients had received galcanezumab (mean [SE]: all patients, −2.4 [0.2] vs. −2.0 [0.2]; EM, −2.3 [0.3] vs. −2.2 [0.3]; CM, −2.1 [0.4] vs. −1.5 [0.4]). The percentage of patients with severe interictal burden decreased substantially for the galcanezumab-treated patients, from 59% (137/232) at baseline to 27% (58/217) at Month 6 (EM from 51% [70/137] to 23% [30/131]; CM from 71% [67/95] to 33% [28/86]). Conclusion: In addition to the known efficacy of galcanezumab in the ictal period, these findings suggest treatment with galcanezumab results in a significant reduction in interictal burden.