CGRP-Targeted Therapy for Episodic and Chronic Cluster Headache.

Two anti-CGRP monoclonal antibodies (i.e., galcanezumab and fremanezumab) completed randomized-control trials for efficacy for the preventive treatment of episodic and chronic CH. Galcanezumab was effective for preventing episodic CH but not chronic CH. Fremanezumab was ineffective in preventing episodic and chronic CH. Studies for other anti-CGRP monoclonal antibodies and CGRP antagonists are still pending for results. There are no randomized controlled trials for CGRP-targeted therapies that showed efficacy for chronic CH prevention. The different responses to galcanezumab between episodic and chronic CH may be due to the study design, i.e., the allowance of concomitant preventive therapies in the chronic CH study but not in the episodic CH study. Another reason for the discrepancies is the different roles and sensitivity of CGRP in chronic CH.