Antibodies bode well for migraines

Antibodies blocking a specific neurotransmitter involved in migraines appear to relieve migraine headaches. Two studies presented at the annual meeting of the American Academy of Neurology reported on the use of antibodies to CGRP (calcitonin gene-related peptide) for the treatment of migraine headaches. These were relatively small, but highly scientific (randomized, double-blind, and placebo-controlled) studies. The studies was conducted in patients with frequent migraines.

The two studies used two different antibodies developed by different companies. The results of the trials suggest that this approach is both effective and safe in preventing migraine, at least according to these preliminary studies.

If these antibodies are proven to be indeed safe and effective, they will be the first specific migraine therapy since the introduction of triptans over 20 years ago. Triptans (sumatriptan and other) are abortive drugs, meaning that abort a migraine attack, while CGRP antibodies are used for the preventive (prophylactic) treatment. While Botox was approved three years ago for the preventive treatment of chronic migraines it was not specifically developed for the treatment of migraines. Instead, Botox was found to have this effect accidentally.

One phase II proof-of-concept trial enrolled 218 people with 4 to 14 migraine headache days per month and randomly assigned them to get the antibody or a placebo. The study medication was given every 2 weeks by subcutaneous injection. Active treatment resulted in reduction of an average of 4.2 migraine days per month in the third month for those on the active drug and a drop of 3.0 days for those on placebo.

The side effects were similar between the groups and most were mild and resolved on their own.

In the other study the antibody was given intravenously at the start of the trial, with an hour-long infusion, but was not repeated. This study enrolled 163 patients, with 82 assigned to the drug and 81 to placebo. The average change from baseline in migraine days per month was a decline of 5.6 for the active treatment compared with a drop of 4.6 for placebo patients. Side effects in this study were also mild and occurred with the same frequency in the active and placebo groups.

While the difference between the active treatment and placebo does not seem to be significant, it was statistically significant and it is possible that some patients will respond very well while others not at all.

The next step is much larger phase III studies, which typically involve over 1,000 patients for each compound. If phase III studies also show safety and efficacy of these antibodies, then the FDA might approve them. This means that the earliest one or both of these drugs will become available is about 3 years.

The companies that sponsored these studies were Arteaus and Alder Biopharmaceuticals.

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