new research suggests. A post hoc analysis of patients from the phase 3 CGAL study who also entered the open-label CGAR extension study was conducted. Results showed that the majority of participants whose scores on the Patient Global Impression of Improvement (PGI-I) showed improvement 1 month after the initial dose of galcanezumab in the CGAL study also showed improvement after treatment for subsequent cluster bouts during the CGAR study.
“There was good agreement between PGI-I between the two [cluster headache] periods,” noted the investigators, led by Brian Plato, DO, a neurologist at Norton Neuroscience Institute in Louisville, Ky.
The findings were presented at the virtual annual meeting of the American Headache Society.
Two cluster periods
Galcanezumab was approved by the Food and Drug Administration in 2019 for the treatment of episodic cluster headache in adults.
In cluster headache, attacks of recurrent, unilateral headaches with cranial autonomic symptoms last for weeks or months and are followed by periods of remission. Most studies of therapies for cluster headache examine only one cluster period. Few data about the consistency of treatment response throughout consecutive cluster periods are available, the investigators noted.
The current analysis was undertaken to examine the consistency of galcanezumab’s effect in episodic cluster headache during two cluster periods. Patients eligible for inclusion in the analysis had completed the double-blind phase of the CGAL study and had entered the open-label CGAR study.
CGAL was a phase 3, multicenter, randomized, double-blind study in which patients with episodic cluster headache were assigned to receive galcanezumab 300 mg per month or placebo. Patients who completed the double-blind and washout phases of this study were eligible for enrollment into CGAR, a phase 3b, single-arm safety study. The investigators determined the dose of galcanezumab in accordance with each patient’s symptoms and clinical response.
Response agreement
In both studies, the PGI-I was administered 1 month after the initial dose of galcanezumab. Only patients who were in an active cluster bout on entry into CGAR and who had valid PGI-I results 1 month after the first dose in CGAL and CGAR were included in the analysis.
PGI-I responses ranged from 1, signifying very much better, to 7, signifying very much worse. The investigators summarized the proportions of patients who reported each level of PGI-I score in CGAR and analyzed the results by dichotomizing PGI-I scores at both time points in two ways.
Fifty patients entered CGAR (78% men; mean age, 46.8 years). Of this group, Dr. Plato and colleagues included 39 in their analysis. Of the 17 patients who had a PGI-I score of 1 or 2 in CGAL, 12 (70.6%) had a score in the same range in CGAR. All four participants who had a score of 3 or higher in CGAL had a score in the same range in CGAR. Eighteen participants had a PGI-I score of 1, 2, or 3 in CGAL. Of this group, 15 patients (83.3%) had a score in the same range in CGAR. Of the three patients who had a score above 3 in CGAL, two (66.7%) had a score in the same range in CGAR.
The results indicate that most patients whose PGI-I score improved in one cluster bout, such as in CGAL, also improved in a subsequent bout, such as in CGAR, the investigators noted.