Early Australian experience with the CGRP inhibitor erenumab (Aimovig) shows it is an effective and well-tolerated migraine preventative therapy in real world usage.
A review of the non-PBS-listed drug’s use in three Australian migraine centres via a product familiarisation program or a $800/month paid access scheme found that it provided consistent responses at three and six months, with effects similar or greater to those seen in randomised controlled trials.
In a prospective analysis of outcomes in 170 patients with chronic migraine who were prescribed erenumab (70 or 140 mg) as prophylaxis, 58.8% of participants met the primary endpoint of having 50% or greater reduction in monthly migraine days at three months, and 46.5% had a 50% or greater reduction at six months.
After starting erenumab patients had a halving in the number of monthly migraine days, from a baseline level of 20.4 to 10.6 at three months and 10.0 at six months.
There were also improvements in other outcomes such as use of triptans, with a reduction from baseline of an average of nine days use per month to four days at six months. Similarly there was a reduction in codeine use from baseline of 5.5 days per month to 2.8 days per month at six months.
Headache impact was reduced by an average of 8.2 points from a baseline of 66.2 according to the HIT-6 assessment.
There was no difference in response rates seen in a small group of patients who had concomitant onabotulinumtoxinA with erenumab treatment.
There were also no differences in response rates for subgroups of patients except for those with triptan medication overuse.
Most of the patients (150 of 170) used the higher 140mg dose, so it was not possible to make meaningful comparisons of the efficacy of the two different doses, said the study authors, Dr Shuli Cheng of Alfred Health, Melbourne and Dr Bronwyn Jenkins of the Royal North Shore Hospital, Sydney.
In their paper, published in the journal Headache, the investigators said the response rates seen in the Australian real world setting were somewhat higher than those seen in randomised controlled trials of erenumab. However this might be due to selection bias of patients being more motivated to enrol in a trial, and clinicians selectively enrolling patients who they thought would be more likely to benefit.
They also noted that the patients who took part in the evaluation tended to have more severe migraines than those in RCTs, as judged by the average number of headache days per months, and included patients who have had three or more previous migraine preventative treatment failures.
There were few adverse events reported, with constipation being the most frequent (seven patients)
The main reasons for discontinuing therapy included lack of efficacy (n = 23), cost (n = 5), pregnancy (n = 1), and worsening constipation in the context of Crohn’s disease (n = 1).
“Our analysis has shown that erenumab is an effective and well-tolerated migraine preventative therapy for patients with chronic migraine, including those who have failed many preventative therapies,” the study authors concluded.
However a PBS listing for erenumab appears unlikely in the near future as the product was withdrawn from the PBAC process by sponsors Novartis in 2019.