SK Biopharm’s U.S. clinical trials of opicopalim (BHV-7000), an epilepsy drug candidate it is seeking to acquire for about $666.7 million, have been placed on partial clinical hold by the U.S. Food and Drug Administration (FDA). Patients currently receiving treatment can continue, but enrollment of new patients will be temporarily suspended.
SK Biopharm disclosed Sept. 10 that its partner, Biohaven, had been notified by the FDA of a Partial Clinical Hold on the RISE2 and RISE3 Phase 2/3 clinical trials of opicopalim in the U.S.
The action is related to toxicity findings observed in a nonclinical toxicity study in which a specific metabolite of opicopalim was administered to rodents. The FDA requested additional nonclinical evidence to determine whether the toxicity is a species-specific phenomenon limited to rodents.
SK Biopharm said it reviewed the toxicity findings during its due diligence before entering into the licensing agreement with Biohaven. Based on the materials available at the time and opinions from outside experts with expertise in toxicology and experience in FDA pharmacology and toxicology reviews, the company assessed the findings as a species-specific phenomenon occurring in rodents and determined that the likelihood of the same issue occurring in humans was limited.
Clinical trials of opicopalim have been conducted in more than 1,200 participants to date. According to SK Biopharm, no adverse events directly associated with the nonclinical toxicity findings have been identified in the clinical data collected so far.
Under the partial clinical hold, patients currently receiving treatment can continue taking the drug, while enrollment of new patients will be temporarily suspended. Because RISE3 has already completed patient enrollment, SK Biopharm said it will maintain its current schedule for releasing topline results in the second half of this year.
Biohaven plans to consult with the FDA, submit additional nonclinical study data evaluating the specific metabolite and seek the lifting of the partial clinical hold.
The opicopalim licensing agreement between SK Biopharm and Biohaven has not yet reached deal closing. The two companies are discussing the matter, including ways to lift the clinical hold.
An SK Biopharm official said, “We are closely reviewing the matter with Biohaven” and added, “We are continuing discussions on the matters necessary to seek the lifting of the partial clinical hold in response to the FDA’s requests.”
SK Biopharm will hold an online briefing the morning of Sept. 11 to explain the background of the action, the status of the clinical trials, additional nonclinical studies and its plans for responding to the issue.
SK Biopharm previously signed an agreement on Aug. 26 to acquire from Biohaven an exclusive global license for opicopalim, other Kv7 activator compounds and related platforms for up to $530 million. The upfront payment is $266.7 million.