Invest1 publisher3 min readPublished
An FDA hold reaches opacalim before SK Biopharmaceuticals pays the $350 million at closing
Kiwoom Securities says the FDA has suspended new enrollment in one of two registrational trials of the epilepsy drug SK Biopharmaceuticals agreed to license from Biohaven last month, and the closing payment is still outstanding.
The Investor · Invest desk
What happened
- Kiwoom Securities said on the 14th that the FDA has put a partial clinical hold on the Phase 2/3 trials of opacalim, the epilepsy candidate SK Biopharmaceuticals is licensing from Biohaven.
- The agency asked for additional preclinical data on whether findings from a rodent toxicity study involving a specific metabolite could also pose a risk to humans.
- Patients already on treatment keep dosing under the hold, while enrollment of new patients is suspended.
- SK Biopharmaceuticals signed for opacalim on the 26th of last month, and because the transaction has not closed the cash due at closing has not been paid.
- Kiwoom said Biohaven expects to file the additional preclinical data as early as late September or early October and hopes the hold is lifted in October or November, with the timing resting with the FDA.
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Why it matters
- exposure SK has not yet parted with the closing money, so the first cost of a longer hold falls on Biohaven, which is the party that has to produce the preclinical package the FDA asked for.
- constraint With RISE2 not enrolling, the filing date for opacalim is set by how quickly the FDA accepts a rodent-metabolite dossier, a clock neither company controls.
- decision Anyone pricing opacalim before 2027 has to price it off RISE3, the only registrational study still running to its original timetable.
- contradiction Kiwoom calls the hold limited in scope and also says it is too early to conclude the safety questions are settled; the same note supports both a buy-the-dip and a wait-for-data reading.
Of the $795 million headline value, $400 million is upfront, and $350 million of that upfront falls due on the day the transaction closes [5]. That single payment is 87.5% of the upfront and 44% of the whole deal [18][20], with $395 million left riding on milestones [19]. It has not been made [6].
Nineteen days separate the signing on the 26th of last month from the Kiwoom note on the 14th [4][1][21]. Kiwoom did not state a closing date or report any change to the agreed terms [22]. So the position is narrow: the FDA wants preclinical data on whether a rodent toxicity finding involving one metabolite carries over to humans [2], and the cash that settles the licence is still with the buyer [6].
The trial split decides how much of that matters. RISE3 has completed patient enrollment and randomization, so its topline stays in the second half of 2026 [7]. RISE2 has stopped taking new patients, and a prolonged hold pushes its results and the new drug application behind it [8].
More than 1,200 people have received opacalim to date, and the company said no clinical adverse events directly linked to the rodent toxicity findings have been identified [9]. Hur Hye-min, an analyst at Kiwoom Securities, said "the bar for verifying opacalim's safety and tolerability has been raised" [11]. Hur also said that "SK Biopharmaceuticals has highlighted safety and tolerability as opacalim's key differentiators, but the FDA's action raises a new question of whether that advantage will hold up in actual patient data" [15].
Three ways this runs. Biohaven's package lands in the window it is aiming at, the hold lifts, RISE2 restarts and the economics of the licence are exactly what was signed [13]. Or the FDA takes longer, RISE2 slips, and the second global drug after cenobamate arrives later than the company planned when it signed [14][8]. Or preclinical work does not answer the metabolite question on its own, and the safety profile that justified $400 million upfront has to be proven in patient data instead [15][5].
In my view the hold costs schedule rather than price, because the payment sits on the buyer's side and the unaffected study is the registrational one that reads out first [6][7]. The case against that is in the same paragraph of the same note: Kiwoom said the actual timing rests with the FDA, which leaves open the possibility of a longer delay [13], and a delay that reaches RISE2's readout reaches the NDA too [8].
"The RISE3 topline results and the lifting of the partial hold will be the key variables for a recovery in investor sentiment," Hur said [16].
What to watch
- Whether the $350 million closing payment is wired before or after the partial hold is lifted, and whether the terms disclosed at signing are the terms at closing.