[Edaily Reporter KIM SUNG-JIN ] SK BIOPHARMACEUTICALS(326030)Attention is focused on when the U.S. Food and Drug Administration (FDA) will lift its partial clinical hold on “Opakalim (BHV-7000),” a new epilepsy drug that SK Biopharm is seeking to license from U.S.-based Biohaven. This is because SK BIOPHARMACEUTICALS had initially expected Biohaven to submit additional data to the FDA by early October, but Biohaven announced that it was still working on the submission even as late as the end of October. Attention is now focused on whether a delay in the lifting of the hold will affect the schedule for finalizing the technology licensing agreement between the two companies.

Nonclinical Data Expected to Be Submitted by Late September… “Data to Be Secured Within Weeks”

According to industry sources on the 8th, Biohaven stated in its third-quarter earnings report released on the 29th of last month that it is working to finalize additional nonclinical safety data for Opakalim. Vlad Korik, CEO of Biohaven, stated, “In the epilepsy field, the key results of the Phase 3 RISE3 clinical trial for the Kv7 activator Opacalym are proceeding on schedule for release in the second half of 2026,” adding, “We are working to finalize the additional non-clinical safety data package and look forward to closing the transaction with SK BIOPHARMACEUTICALS.”

This is understood to be somewhat behind the schedule SK BIOPHARMACEUTICALS presented last September. Yoo Chang-ho, Head of Strategy at SK BIOPHARMACEUTICALS, stated during an online briefing on September 11, “Biohaven plans to submit additional data to the FDA in late September or early October,” adding, “We expect the clinical hold to be lifted as early as late October or November.”

It is expected that Biohaven’s submission of additional nonclinical data will take some time. Biohaven projected that it would take several weeks to secure the additional nonclinical data. This suggests that securing the data is taking longer than initially anticipated. On September 9, Biohaven disclosed the FDA’s partial clinical hold while anticipating that the additional nonclinical data would be secured “within the next few weeks.” However, the company maintained the same outlook even at the end of October, approximately seven weeks later.

The issue is that the longer the submission of data is delayed, the more the FDA’s review schedule may also be delayed. FDA regulations stipulate that the agency must notify the company within 30 days of receiving a complete response addressing the reasons for the clinical hold whether the hold will be maintained or lifted. If securing and submitting the additional data takes longer, the timing of the hold’s lifting may also be later than originally anticipated. If Biohaven does not submit the additional data by November, the FDA’s lifting of the clinical hold could be pushed back to next year.

Transaction Closure on Hold Due to Clinical Hold… Will This Become a Variable for Commercialization in 2029

? The timing of the clinical hold’s lifting is also expected to affect the schedule for the closing of the technology licensing deal between SK BIOPHARMACEUTICALS and Biohaven. SK BIOPHARMACEUTICALS previously explained that it is in discussions with Biohaven to close the deal after resolving the FDA’s partial clinical hold. The plan is to finalize the contract after confirming the outcome of the clinical hold’s lifting.

SK BIOPHARMACEUTICALS maintains that it identified the toxicity findings during the due diligence process prior to signing the contract and reviewed them with external experts. The company assessed that this toxicity is likely a specific phenomenon observed only in rodents.

The timing of the agreement between SK BIOPHARMACEUTICALS and Biohaven is an issue that could also affect future performance. This is because SK BIOPHARMACEUTICALS effectively relies on Excofry for the majority of its revenue; only by successfully commercializing Opakalim after its acquisition will the company be able to expand into the epilepsy market and diversify its portfolio. SK BIOPHARMACEUTICALS has currently set the commercialization timeline for Opakalim for 2029, but if the lifting of the clinical hold is delayed, there is a possibility that this commercialization schedule could change.

The waiting period under the U.S. Hart-Scott-Rodino Antitrust Improvements Act (HSR)—one of the regulatory procedures required to close the transaction between the two companies—has ended. The HSR Act requires prior notification to the U.S. Federal Trade Commission (FTC) and the Department of Justice (DOJ) for transactions such as mergers and acquisitions or asset acquisitions involving companies above a certain size, and prohibits the completion of the transaction until a specified waiting period has elapsed. A 30-day waiting period is typically applied as part of the process to review potential restrictions on competition in advance. The expiration of the waiting period means the transaction can be finalized provided other transaction conditions are met.

Opakalim is a new drug candidate for epilepsy, designed to selectively activate the Kv7 potassium channel, which regulates the excitability of brain neurons. Last August, SK BIOPHARMACEUTICALS signed an agreement with Biohaven to secure global exclusive rights to develop and commercialize the Kv7 platform, including Opacalym. This investment was intended to secure a new growth engine following “cenobamate” (U.S. brand name: Xcopri), an epilepsy treatment developed in-house by SK BIOPHARMACEUTICALS.

However, an unexpected development arose immediately after the agreement was signed. The FDA issued a partial clinical hold on Opacalym. Toxicological findings were observed in preclinical studies where a specific metabolite of Opacalym was administered to rodents, and the FDA stated that further confirmation was needed to determine whether these findings were species-specific to rodents. Consequently, the FDA ordered a halt to the enrollment of new patients until additional nonclinical data is obtained. However, treatment may continue for patients already enrolled, and the Phase 3 RISE3 clinical trial is currently proceeding according to the original schedule.

Closing deadline undisclosed… Contract may be terminated in case of prolonged delay

A key point to note is that the two companies separately established a final closing deadline in the agreement. According to the license agreement Biohaven filed with the U.S. Securities and Exchange Commission (SEC), the two companies set a deadline (Outside Date) requiring the transaction to be closed within a certain period from the date the agreement was signed. However, the specific deadline was not disclosed, citing trade secrets. The significance of when the clinical trial suspension is lifted is expected to vary significantly depending on when this deadline is set.

Although the specific date is not specified, the agreement appears to include a clause stating that if the transaction is not closed by the deadline set by both parties, SK BIOPHARMACEUTICALS and Biohaven may each terminate the agreement. At the same time, provisions have been made to extend this deadline: SK BIOPHARMACEUTICALS may extend the deadline once on its own, and further extensions are possible if both parties agree.

The size of the upfront payment provides an indication of just how much SK BIOPHARMACEUTICALS is banking on Opakalim. SK BIOPHARMACEUTICALS signed a technology licensing agreement with Biohaven totaling $795 million, of which the upfront payment alone amounts to $400 million. The structure calls for a payment of $350 million upon closing of the transaction and an additional $50 million one year after closing. The upfront payment is non-refundable once the agreement is signed.

SK BIOPHARMACEUTICALS has agreed to pay Biohaven up to $150 million in milestone payments based on development and regulatory milestones, and to assume payment obligations of up to $245 million related to existing technologies. Following commercialization, SK Biopharm must pay Biohaven royalties ranging from the mid-10% to low-20% range of net sales in the U.S. and in the mid-single digits of net sales outside the U.S. SK Biopharm has also assumed the obligation to pay royalties of 4–6% to Knopp, the original developer.

Biohaven plans to announce the key results of the Phase 3 RISE3 clinical trial, for which patient enrollment has been completed, in the second half of this year. These clinical results are expected to serve as a key indicator of Opacalym’s commercial value and future development strategy.