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Safe so far
NEW HAVEN, Conn.—Early signs from a long-term study of rimegepant are looking good for Biohaven Pharmaceutical Holding Co. Ltd. (Biohaven), as interim analysis shows that the drug candidate seems to be safety and well tolerated with long-term dosing in migraine patients. The ongoing open-label safety study (Study 201) features migraine patients who are allowed to treat their attacks—from mild to severe in intensity—with rimegepant up to once daily for up to a full year.
Rimegepant is an oral calcitonin gene-related peptide (CGRP) receptor antagonist under evaluation for acute treatment of migraine. As explained on Biohaven's website, “The CGRP receptor is located within pain-signaling pathways, intracranial arteries and mast cells and its activation is thought to play a causal role in migraine pathophysiology … Additionally, multiple clinical studies show that small molecule CGRP receptor antagonists, which inhibit the binding of endogenous CGRP to CGRP receptors, are effective in aborting migraine attacks.” The company points to three main mechanisms by which this treatment approach is thought to offer migraine relief: by blocking neurogenic inflammation; by decreasing artery dilation; and by inhibiting pain transmission through inhibition of “the central relay of pain signals from the trigeminal nerve to the caudal tirgeminal nucleus.”
Study 201 had dosed 1,780 adult patients as of Nov. 21, the interim data analysis cutoff, with approximately 473 patients having received near-daily dosing (≥15 doses per month) of rimegepant 75 mg for anywhere between one and 12 months. The safety and tolerability for up to one year of dosing was consistent with previous studies, and liver safety/tolerability is also encouraging. Interim data were reviewed by an external independent panel of liver experts, according to Biohaven, and the panel did not determine any liver cases as probably related to the drug, with no Hy's Law cases (the likelihood that patients are at high risk of fatal drug-induced liver injury) identified. No liver safety signal was detected through the Nov. 21 cutoff date, even in those patients receiving near-daily dosing. Additionally, “[i]n aggregate, the panel noted that, compared to placebo arms of other migraine treatments, there was a very low incidence of overall elevations of liver laboratory abnormalities (1.0% incidence of serum ALT or AST > 3xULN).”
"The totality of the interim results from this long-term dosing trial with rimegepant provides important safety information for our planned NDA submission and also preliminary proof of concept for pursuing rimegepant for both the acute and preventive treatment of migraine,” said Dr. Vlad Coric, CEO of Biohaven. “The clinical outcomes and data from this long-term study to date are particularly meaningful because of the large number of patients who took rimegepant to treat migraine as they would in the real-world, allowing patients to treat every migraine attack, even if mild, up to once daily for one year. We believe rimegepant has the potential to truly improve the lives of patients who suffer from debilitating migraine, and we look forward to submitting the NDA for this promising new treatment option in 2019."
Efficacy data for rimegepant is also promising, with interim data implying that the drug candidate results in a reduction in migraine days per month in a potentially preventive effect. An exploratory analysis showed that study participants who suffered ≥15 migraine days per month in the observation period of the study saw a mean reduction of four headache days per month by 12 weeks of intermittent dosing. Roughly 40 percent of patients with ≥15 migraine days per month in the observation period saw their monthly number of headache days drop by 30 percent or more by 12 weeks of treatments.
Dr. Robert Croop, chief development officer – Neurology at Biohaven, commented, "We are grateful to the almost 2,000 patients and the clinical trial sites who have participated in this trial to establish the safety and tolerability of rimegepant long-term dosing. We look forward to the potential for bringing rimegepant to broader patient populations both in the US and globally."
The Global Burden of Disease Study 2015 highlighted migraine as the seventh highest specific cause of disability globally, while the Migraine Research Foundation identifies it as the third most prevalent illness worldwide. The common medications for migraine include triptans, ergotamine derivatives, non-steroidal anti-inflammatory drugs (NSAIDs), opioids or combination medications, Biohaven reports, with triptans standing as the current standard of care for a majority of migraine patients. However, many patients see incomplete pain relief or headache recurrence when using triptans. In addition, these drugs are not recommended for patients with cardiovascular or cerebrovascular disease, according to Biohaven, or those with a history of conditions such as ischemic heart disease, coronary artery vasospasm, history of stroke, peripheral vascular disease or uncontrolled hypertension.
Given the shortcomings of triptans, as well as the known issues with extended opioid use and the fact that NSAIDs have their own ties to issues such as hypertension and heart attack/stroke risk, it's no wonder Biohaven feels there is a promising opening in the market for a new migraine treatment option. Rimegepant has been tested in four randomized trials so far, including a Phase 2b and three Phase 3 studies, and Biohaven intends to submit a New Drug Application to the FDA for the compound next year.