Adding CGRP to Botox Safe, Effective for Migraine Prevention

Erik Greb

June 18, 2020

Adjunctive preventive therapy with a calcitonin gene-related peptide monoclonal antibody (CGRP-mAb) medication is safe and effective in patients with chronic migraine who have only achieved a partial response to onabotulinumtoxinA (Botox) treatment.

Investigators found the CGRP-mAbs significantly reduced the number of headache days and pain severity with adverse event rates similar to those reported in previous trials of these medications.

"The addition of a CGRP monoclonal antibody provided statistically significantly fewer monthly headache days," said study investigator Fred Cohen, MD, an internal medicine resident physician at Montefiore Health System in New York City. "However, this was a retrospective chart review, which is hindered by elements such as recall bias. Therefore, future prospective studies are warranted for higher quality data."

The findings were presented at the American Headache Society (AHS) Annual Meeting 2020, which was virtual this year because of the COVID-19 pandemic.

Fewer Headache Days

Although Botox it is associated with significant clinical improvement in chronic migraine, it often fails to adequately control headache frequency and additional medications are needed.

As previously reported by Medscape Medical News, CGRP-mAbs fremanezumab, galcanezumab, and erenumab, have recently been approved for migraine prevention, with results from clinical trials demonstrating they are effective for both chronic and episodic migraine. However, patients treated with Botox were excluded from these trials and, to date, there are no data on combination treatment with Botox and CGRP-mAbs.

To determine whether adjunctive treatment with CGRP-mAbs augments Botox therapy in chronic migraine the investigators conducted a retrospective chart review of patients receiving Botox and prescribed a CGRP-mAb.

Eligible patients met the International Classification of Headache Disorders, third edition, criteria for chronic migraine; were age 18 years or older; and presented at a single headache center between May 2018 and May 2019. Patients who received another new therapy during the study or those taking CGRP-mAb treatment for less than 2 months were excluded.

The study's primary outcome was change in the number of reported monthly headache days. Change in pain severity was the secondary outcome.

The final analysis included data on 153 patients. The population's mean age was 47.1 years, and 139 patients (90.8%) were women. In all, 89 patients (58.0%) received erenumab (35 received 70 mg and 54 received 140 mg), 51 (33.0%) received galcanezumab, and 13 (9.0%) received fremanezumab.

Overall, 114 (74.5%) patients reported a decrease in monthly headache days or pain severity. In the group of 66 patients for whom quantitative data were available, the average number of monthly headache days before Botox treatment was 25.7. After Botox treatment, patients had an average decrease of 10.9 monthly headache days, a 42.4% reduction, so on average study participants continued to have an average of 14.8 monthly headache days.

After treatment with a CGRP-mAb the number decreased by 5.6 additional days (37.8%). Patients receiving combined therapy had an average of 9.1 monthly headache days. The total decrease from baseline was 16.6 fewer monthly headache days, a 64.6% reduction.

The number of headache days per month was reduced to 9.3 for erenumab and galcanezumab and 5.8 for fremanezumab. However, few patients in the study took fremanezumab so this result had less statistical power than the results for the other CGRP-mAbs.

Thirteen patients (8.5%) reported side effects associated with the CGRP-mAbs, which included constipation, injection-site reaction, and fatigue.

More Evidence Is Needed

Commenting on the findings for Medscape Medical News, Peter McAllister, MD, medical director of the New England Institute for Neurology and Headache in Stamford, Connecticut, said the study's main limitation is that it is a retrospective chart review, which yields lower level evidence than a prospective, double-blind, placebo-controlled study. McAllister, who was not involved in the research, also noted that the sample size was small, particularly with respect to fremanezumab.

"This study, despite its limitations, shows that addition of a monoclonal antibody to onabotulinumtoxinA is safe and well tolerated, and may confer additional reduction in migraine or headache days. The authors correctly state that more evidence via prospective study is warranted," said McAllister, who is also chief medical officer of the New England Institute for Clinical Research and was not involved in the investigation.

Cohen has reported no relevant financial relationships. McAllister was an investigator in the PREEMPT trial of onabotulinumtoxinA, as well as in all of the phase 3 monoclonal antibody studies.

American Headache Society (AHS) Annual Meeting 2020. Abstract 825289. Presented June 13, 2020.

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