Anti-CGRP monoclonal antibodies for migraine prevention: A systematic review and likelihood to help or harm analysis

Introduction and objective Monoclonal antibodies targeting the calcitonin gene-related peptide pathway (anti-CGRP mAbs) have shown promising efficacy in randomised clinical trials for the prevention of episodic and chronic migraine, but no head-to-head comparisons with established treatments are available. We aimed to examine absolute differences in benefit-risk ratios between anti-CGRP mAbs, topiramate and propranolol for the prevention of episodic migraine and between anti-CGRP mAbs, topiramate and onabotulinumtoxinA for the prevention of chronic migraine using a likelihood to help versus harm analysis. Methods The number of patients needed to be treated for a patient to achieve >= 50% reduction in migraine days (NNTB50%) was used as an effect size metric of efficacy. The number of patients needed to be treated for a patient to experience an adverse event that led to treatment discontinuation (NNTHD-AE) was used as a measure of risk. Likelihood to help versus harm values - which are the ratios of NNTH:NNTB - were calculated using data from phase 3 randomised clinical trials. Results All agents tested were more likely to be beneficial than harmful (likelihood to help versus harm > 1) with the exception of topiramate at 200 mg per day for the prevention of episodic migraine. Anti-CGRP mAbs in all tested doses had higher LHH values than propranolol or topiramate for episodic migraine and onabotulinumtoxinA or topiramate for chronic migraine prevention. Fremanezumab had the highest LHH ratio in episodic migraine and galcanezumab in chronic migraine. Conclusion This analysis showed that anti-CGRP mAbs exhibit a more favourable benefit-risk ratio than established treatments for episodic and chronic migraine. Head-to-head studies are needed to confirm these results.