Calcitonin gene-related peptide(CGRP) antagonists, including erenumab (Aimovig), fremanezumab (Ajovy) and galcanezumab (Emgality), are the newest class of drugs to be licensed for the prophylaxis of migraine.
Acting through blockade of the CGRP receptor, thought to be involved in the transmission of pain signals associated with migraine, these drugs are administered by injection once per month (with the option of administering once every three months for Ajovy).
Although the optimum duration of treatment with CGRP antagonists is yet to be determined, guidelines from the European Headache Federation recommend stopping prophylactic treatment with these drugs after six to 12 months of successful therapy.
Researchers conducted a longitudinal cohort study (n=62) to assess the course of migraine after stopping treatment with a CGRP antagonist.
Patients included in the study had be on their first prophylactic treatment with a CGRP antagonist (erenumab [n=31] fremanezumab or galcanezumab [n=31]), be on monotherapy and to have received a minimum of eight CGRP antagonist injections at a frequency of one per month.
Baseline headache data for the the four-week period preceeding the start of CGRP antagonist therapy was collected retrospectively from patient records. Patients attended three prospective study visits, at the first of which they received their final dose of CGRP antagonist; the second and third visits were scheduled for eight and 16 weeks after this final dose.
Migraine frequency increased
The number of monthly migraine days (MMD) increased significantly from 8.2 days in the four-week period before the last treatment to 10.3 days in weeks 5 to 8 (p=0.001) and to 12.5 days in weeks 13 to 16 (p<0.001).
Migraine frequency remained significantly lower than at baseline during weeks 5 to 8 (-2.9 MMD, p=0.033) but returned to baseline levels during weeks 13 to 16 (-0.8 MMD, p>0.999). Monthly headache days and monthly days with acute medication use (including both triptans and non-triptans [eg, NSAIDs]) increased in parallel over time.
The researchers conclude that larger scale placebo-controlled studies are needed to corroborate their findings and also to identify predictors for successful treatment discontinuation.