sensory trigeminal nerve fibers release CGRP. This causes blood vessel dilation and inflammation, which likely results in the pain associated with a migraine. Immunotherapies for migraine, therefore, involve antibodies that target either CGRP or its receptors, blocking the sequence of events that cause pain.
there are three on the market now: erenumab (Aimovig) by Amgen and Novartis; fremanezumab (Ajovy) by Teva, and galcanezumab (Emgality) by Eli Lilly. A fourth drug called eptinezumab, produced by Alder Biopharmaceuticals, just cleared Phase III clinical trials. The antibodies are injected monthly or every few months.
A new group of injectable drugs inhibit a protein thought to trigger migraines, but not all insurance plans cover it -- and many people can’t afford the $575 a month price tag.