The gepants and monoclonal antibodies (mAbs) against calcitonin gene-related peptide (CGRP) and its receptor appear to be effective, tolerable and safe, according to several posters recently presented at the 2019 American Academy of Neurology (AAN) Annual Meeting in Philadelphia. Information was presented on the 3 gepants being studied for US Food and Drug Administration (FDA) approval: 1 for acute care of migraine, 1 for prevention and 1 for both (though the presented data for rimegepant only covers acute care).
All drugs cause a small degree of adverse events (AEs), somewhat more than placebo. Based on the presented data, it seems that those associated with 3 times higher than normal elevation of liver enzymes, were usually not found to be the cause of that elevation. At no time was bilirubin elevated. This shows that all of these gepants appear to be effective and safe, despite the fact that some were found to have cause liver toxicity many years ago.
The first gepant study to be published was on olcegepant in 2004, in the New England Journal of Medicine. Professor Jes Olesen, MD, was the lead author of the study, which detailed the efficacy and safety of this small molecule CGRP receptor antagonist. Olcegepant was in an intravenous formulation and the plan was to convert it to a tablet, which never happened. Another company then produced telcagepant as a tablet and it was shown to be safe and effective in 2 large, multicenter, double-blind trials. Before receiving FDA approval for the acute care of migraine, it was studied on a daily basis for migraine prevention. It was found to cause some liver toxicity, so development was stopped. At that time several other gepants in development were placed on the shelf, partially for the fear of liver toxicity. The FDA is unlikely to approve a drug with significant liver toxicity, which can cause a range of symptoms including jaundice, itching, abdominal pain, fatigue, loss of appetite, nausea, vomiting, rash, and weight loss.
In the next few years we will have 4 mAbs for the prevention of migraine, and 3 gepants if all studies are positive. Below are the key takeaways from the presented posters on ubrogepant and atogepant, as information that is currently available on rimegepant.
- Ubrogepant – Ailani J, Hutchinson S, Lipton R, et al.
- Intermittent use of ubrogepant for the acute treatment of migraine over 1 year was well-tolerated with no identified safety concerns. Throughout the 1-year, Phase III study of 1254 participants, 22,454 migraine attacks were treated with 31,968 doses of ubrogepant.
- Twenty cases of ALT/AST ≥3x ULN were reported and adjudicated by an independent panel of liver experts blinded to treatment.
- Of the 20 cases, 17 (4 usual care, 3 ubrogepant 50-mg, and 10 ubrogepant 100-mg) were determined to be unlikely related based on plausible alternative etiology/confounding factors.
- Just 2 cases (both ubrogepant 50-mg) were described as possibly related to study medication and 1 case (ubrogepant 100-mg) was adjudicated as probably related ; however, confounding factors were noted.
- All cases were asymptomatic with no concurrent bilirubin elevation. ALT/AST elevations resolved in those who continued dosing.
- Atogepant – Goadsby PJ, Dodick DW, Trugman JM, et al.
- In a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial of adults with a history of migraine, with or without aura, atogepant was well tolerated with no treatment-related serious AEs.
- Of the 834 randomized subjects, 825 were evaluated in the safety population. Treatment-emergent AEs were reported by 480 subjects (58.2%), and for 170 (20.6%), the AEs were considered treatment-related. Seven subjects (0.8%) reported serious AEs, but none were determined as treatment related.
- There were 10 cases of treatment-emergent ALT/AST elevations >3x the upper limit of normal, and this was balanced across the treatment dosage groups (10 mg QD, 30 mg QD, 30 mg BID, 60 mg QD, and 60 mg BID).
- Rimegepant – See Biogen press release for more information
- In December 2019, Biohaven announced initial positive results from an ongoing long-term, open-label safety study for rimegepant.
- The interim results included hepatic safety and tolerability data of rimegepant 75 mg in study participants based on a review of adverse events and regularly scheduled liver function tests.
- A panel of external independent liver experts provided a consensus based on the Drug-Induced Liver Injury Network (DILIN) causality assessment, determining that there were no liver cases probably related to the study drug and that there were no Hy’s Law cases identified.
- The panel also concluded that there were no liver safety signals detected and that, compared to placebo arms of other migraine treatments, there was a very low incidence of overall elevations of liver abnormalities.