BACKGROUND: Patients with migraine, particularly with multiple prior preventive treatment failures, often have high rates of acute headache medication use and are at risk for overuse (acute or symptomatic headache medication use between 10 and 15 days per month [depending on the medication] for > 3 months). Furthermore, these patients have greater health care resource utilization (HCRU). OBJECTIVE: To examine acute headache medication use and HCRU with galcanezumab compared with placebo in a population with multiple prior migraine preventive treatment failures. METHODS: In the 3-month double-blind phase, patients with episodic or chronic migraine and treatment failures to 2 to 4 standard-of-care migraine preventive categories (lack of effectiveness or safety/tolerability) received galcanezumab 120 mg/month (following a 240-mg loading dose) or placebo; an optional 3 month open-label phase followed. Acute headache medication use (monthly days with acute headache medication utilization) was self-reported daily. The change from baseline in monthly days with acute headache medication used a mixed-model repeated measures analysis. HCRU was reported at baseline (for the previous 6 months) and at monthly visits. Migraine-related HCRU rates were evaluated in the total population per 100 patient-years. RESULTS: Of the 462 patients (galcanezumab n=232, placebo n=230), baseline mean days/month of acute headache medication was 12.3; 44.8% had acute headache medication overuse. Across months 1-3, least squares (LS) mean reductions in acute headache medication use were greater for the galcanezumab group (4.2) compared with placebo (0.9); the LS mean difference was 3.4 (95% CI = 2.7-4.1; P < 0.0001). Greater reductions in the galcanezumab group were observed as early as month 1; statistical separation continued at months 2 and 3 (all P < 0.0001). During the open-label phase, reductions from baseline ranged from 4.7 to 5.3 days and were similar in patients who transitioned from placebo to patients continuing galcanezumab. Reductions from baseline of migraine-specific health care visits (double-blind phase) were numerically greater with galcanezumab than placebo (215.5 vs 155.3). Patients switching to galcanezumab had reductions (212.9 days) similar to patients continuing galcanezumab (222.6 days). Migraine-specific emergency department visits decreased by two-thirds at month 3 in the galcanezumab group compared with nearly no reduction in the placebo group that experienced a similar reduction during the open-label phase. For both groups, migraine-specific hospitalizations were less than 2 per 100 patient-years. CONCLUSIONS: These results demonstrate that galcanezumab has the potential to reduce acute headache medication use and overuse and HCRU in patients with prior migraine preventive treatment failures. DISCLOSURES: Data were presented in part as a poster presentation at the 14th European Headache Congress (European Headache Federation), Virtual Meeting, July 3-5, 2020. Dr Ambrosini is on the advisory board for Eli Lilly and Company and received honorarium from Teva, Novartis, and Eli Lilly and Company. Dr Estemalik is on the advisory boards for Eli Lilly and Company, Lundbeck, and Allergan and the speakers' bureau for Teva, Lundbeck, Eli Lilly and Company, Allergan, and Biohaven. He received consulting fees from Eli Lilly and Company, Teva, Lundbeck, and Allergan and support for attending meetings and/or travel from Eli Lilly and Company, Allergan, Biohaven, Teva, and Lundbeck. Dr Pascual received research support from Instituto de Salud Carlos III, Ministry of Economy, Spain. He was also on advisory boards for Allergan, Amgen-Novartis, Eli Lilly and Company, and Stendhal and received consulting fees or honoraria from Allegan, Eli Lilly and Company, Novartis-Amgen, and Teva. Dr Rettiganti is an employee of Eli Lilly and Company and/or one of its subsidiaries, Indianapolis, IN. She is also a minor stock and restricted stockholder of Eli Lilly and Company. Mr. Stroud and Ms. Day are employees of Eli Lilly and Company and/or one of its subsidiaries, Indianapolis, IN. Dr Ford is an employee of and holds stock of Eli Lilly and Company and/or one of its subsidiaries, Indianapolis, IN. She also received support for attending meetings and/or travel from Eli Lilly and Company.