An experimental drug from Eli Lilly & Co. significantly reduced patients’ number of migraines in a series of final-stage trials, bringing the medicine closer to approval in a competitive field.

In all three studies, patients taking Lilly’s drug galcanezumab had about two fewer days with episodic and chronic migraines over the course of a month compared with those getting placebo, the company said Thursday in a statement. Lilly plans to file for approval of the medicine with the U.S. Food and Drug Administration by the end of the year.

Indianapolis-based Lilly is in a race with drugmakers including Teva Pharmaceutical Industries Ltd., Amgen Inc. and Alder Biopharmaceuticals Inc. to develop migraine treatments using an approach known as anti-CGRP. The drugs block the CGRP protein, which is believed to have an important role in pain and migraines.

The drugs are expected to create a multi-billion-dollar market if they are approved by regulators and can outperform older, generic migraine medicines and Allergan Plc’s wrinkle-treatment Botox, which is also used to treat the painful episodes. Lilly’s drug is projected by analysts to have about $480 million in sales in 2021, according to data compiled by Bloomberg.

Patients in Lilly’s Evolve-1 and Evolve-2 studies suffered from episodic migraines, while those in the study called Regain had chronic migraines. To be eligible, patients for the Evolve studies had to experience between four and 14 days with migraines a month, while the Regain study started with an average of 19.4 migraine days a month.

Trial Results

The average reduction in the number of days with migraine in each trial:

The most common side effect in the three studies was pain and other reactions where the medicine was injected, the Indianapolis-based company said.

Lilly also is evaluating galcanezumab for treating cluster headache, with final-stage trial results expected next year.

Migraines are one of the most common neurological disorders. About 38 million people in the U.S., most of them women, suffer symptoms that extend beyond head pain, ranging from vomiting to disturbed vision, according to the Migraine Research Foundation.