The use of biologicals is associated with injection-site reactions. In this post hoc analysis of Phase 3 studies including migraine patients, the most common but mild to the moderate adverse event reported was the incidence of injection-site pain.

The study authors aimed to provide a comprehensive overview and detailed summary of injection-site reaction associated with the use of galcanezumab in migraine patients.

The relevant information was gathered from 2 randomised clinical trials which included episodic migraine patients (EVOLVE-1 and EVOLVE-2), 1 randomised study comprising of patients with chronic migraine (REGAIN) and 1 open-label study (Study CGAJ) comprising of patients with episodic or chronic migraine patients.

Injection-site reactions were assessed for 2 different cohorts, namely:

1) The placebo-controlled analysis set: 6-month double-blind treatment phase in the EVOLVE-1 and EVOLVE-2 studies and 3-month double-blind treatment phase in the REGAIN study. In these, patients were given placebo and galcanezumab;

2) Galcanezumab exposure analysis set: 3 months double-blind (Month 0- 3; 1:1; placebo:galcanezumab) + 9 months open-label extension phase (Month 3 to Month 12) of REGAIN and 12-month open-label phase of Study CGAJ. Here, patients were given the only galcanezumab.

In the placebo-controlled analysis set, 477 participants (galcanezumab 240 mg, 166/730 [22.7%]; galcanezumab 120 mg, 128/705 [18.2%]; placebo, 183/1451 [12.6%]) described at least 1 injection-site reaction. Mostly, injection-site reactions were designated as an unspecified injection-site reaction, injection-site pain, injection-site erythema, and injection-site pruritus. Injection-site pain was most commonly observed with similar frequency by patients receiving galcanezumab (galcanezumab 120 mg, 240 mg, 10.1%, 11.6%, respectively) and placebo (9.5%) and within 60 min of injection (~ 86% participants).

The occurrence of unspecified injection-site, erythema and pruritus were significantly greater in patients receiving galcanezumab than placebo. Patients received 12 doses in the galcanezumab exposure analysis set and the incidence of injection-site reactions described for both doses altogether was 21.8%. But, injection-site reactions did not escalate with the number of doses. There were no ISR-related serious adverse events reported.

Injection-site reactions are most frequently observed with galcanezumab usage. But, their severity varies generally as mild-to-moderate, are non-serious and resolved spontaneously. Withdrawals because of injection-site reactions were low (1%).