FDA reopens Biohaven ataxia drug review; 29% jump faces panel test

Biohaven became a separate public company on October 3, 2022, and it has not yet earned any revenue from product sales.¹ After the 2025 rejection it narrowed its spending to three late-stage programs: drugs that clear harmful antibodies from the blood, the epilepsy drug opakalim, and taldefgrobep alfa, a muscle drug being tested in obesity.²

Troriluzole is aimed at spinocerebellar ataxia, an orphan nerve disease with no approved drug therapy, which affects about 15,000 people in the United States.¹ Its road has been rough. Its main placebo-controlled trial missed its primary goal in the full patient group, and in July 2023 the FDA refused to review a first application.²

The FDA accepted a second application with priority review in February 2025. Biohaven's case leaned on a three-year real-world study that, the company says, showed 50-70% slower decline than matched untreated patients drawn from outside registries.¹ On November 4, 2025 the FDA turned it down, citing possible bias, design flaws, a lack of pre-set plans and unmeasured confounding factors in that kind of evidence.² The agency had planned an advisory panel for that review and called it off weeks before the meeting, Biohaven said at the time. The shares fell more than 40% the next day, Reuters reported.³

To stay funded, Biohaven sold $178.9 million of new shares in the first quarter of 2026.¹ On August 26, 2026 it licensed its epilepsy platform, led by opakalim, to SK Biopharmaceuticals for a $400 million upfront fee: $350 million at closing and $50 million a year later.² On September 4 the FDA paused new enrollment in the opakalim trials over a finding in rodents, though dosing goes on for more than 600 patients already enrolled.³ In a filing on October 15, 2026, Biohaven reported licensing its antibody-clearing drugs in Japan, South Korea, Taiwan and Southeast Asia to Ono Pharmaceutical for $80 million upfront.⁴

The FDA told Biohaven it accepted the refiled application for review and considers it a complete response to the November 4, 2025 rejection letter.¹ It set a user-fee goal date, its target for a decision, in the first quarter of 2027, without naming a day.²

The FDA also plans to convene its Peripheral and Central Nervous System Advisory Committee, a panel of outside experts, to hear from outside voices, and says the date will come in the near term.¹ That cuts both ways. A panel gives Biohaven the public hearing it lost last time, when the planned meeting was called off, but it also means the agency wants outside input before it decides.²

The filing is careful about what the acceptance does not mean. The goal date does not assure that the FDA will act by then or approve, and the agency may extend the review, ask for more information or reject the drug again.¹ Troriluzole is still unapproved for any use in the United States. The refiling included new positive supportive analyses, and the 8-K does not say what they measure or whether they add new patients.²

Investors took the news well. BHVN closed at $11.81 on October 20, 2026 and was $15.235 at 10:40 ET on October 22, up 29.0%, while the S&P 500 fund fell 0.8%.¹ Our price file starts in mid-September, with a $12.335 close on September 15, so a full-year price range is not available.² Since then the stock has closed as low as $10.795 on October 16 and as high as $14.86 on September 22.³

With 151.0 million shares out, the gain added about $517 million of market value, lifting Biohaven to about $2.3 billion from about $1.78 billion.¹ With no product sales, there is no revenue, operating profit or free cash flow to measure the news against.²

An approval would not hand Biohaven all of the drug's value. Its lender, an affiliate of Oberland Capital, holds senior secured notes backed by Biohaven's cash, its equity interests and its troriluzole assets.¹ The lender gets 6.25% of troriluzole's global net sales to start, and a payment equal to 35% of the funded amount on an FDA or European approval, about $87.5 million on the $250 million funded.²

At June 30, 2026 Biohaven held $238.0 million of cash and $29.8 million of marketable securities, $267.9 million in all.¹ It used $235.0 million in operations in the first half of 2026. That included a one-time $42.7 million payment to Knopp Biosciences, the seller of its epilepsy platform; without it, the pace was about $96 million a quarter, so June cash covered about 2.8 quarters before new money.² Management says its cash and securities will fund the company for at least one year after the second-quarter report.³

The notes carry a trap. If the auditor's opinion on the 2026 accounts, due by March 1, 2027, carries a going-concern warning, Biohaven breaches the notes, and the $250.0 million outstanding plus a premium could be called early.¹ Against the $250 million face value, June cash left net cash of only about $17.9 million, and from 18 months after the April 28, 2025 closing the repurchase price steps up to 175% of the funded amount, about $437.5 million, more than June cash and investments.²

The licensing deals answer that risk if they pay as planned. SK's $350 million is payable at closing, which needs antitrust clearance, and in a filing on September 10, 2026 Biohaven said the two companies were still working to complete the required antitrust filing.¹ The same filing said all clinical and nonclinical data, including the metabolite data, were disclosed to SK before signing; the license agreement makes closing depend on Biohaven's representations, including that no regulator had ordered a clinical hold, still being true, but that condition fails only if the inaccuracy would reasonably be expected to have a Material Adverse Effect.² Ono's $80 million is non-refundable and payable on closing, and another $20 million comes only if Ono chooses to continue after stability test results.³ Together the two upfront sums come to $430 million, enough for about 4.5 quarters at the first-half pace.⁴

The losses are mostly cash. The second-quarter GAAP net loss was $137.3 million, and the adjusted loss, which leaves out non-cash stock pay and losses on derivatives, was $118.1 million.¹ Stock pay was $19.2 million in the quarter, and the loss also held a $14.6 million paper loss from marking the notes to fair value.² The notes are repaid through a share of troriluzole sales and approval payments up to a cap of 1.95 times the funded amount, about $487.5 million, which rises to 2.10 or 2.25 times, about $525 million to $562.5 million, if payments by the test date are under half the funded amount; if troriluzole misses the December 31, 2030 test, a true-up of the funded amount less payments received falls due, and any cap shortfall is owed as a balloon by the eighth or tenth anniversary.³

Shareholders have already paid for the wait in dilution. Weighted shares in the second quarter were 150.6 million, up 47% from 102.4 million a year earlier.¹ Options and stock units on another 21.3 million shares, about 14% more, sit outside that count; their average exercise price of $18.72 is above today's price, but 5.2 million options granted this year at an average $11.34 are in the money.² Biohaven can still sell up to $350.0 million of new shares through its at-the-market program, and the secured notes are paid ahead of common shareholders.³

The bull case: after telling Biohaven in 2025 to meet and discuss what evidence a future application would need, the FDA has accepted the refiling and is giving the drug a public panel.¹ The disease has no approved drug, troriluzole has orphan drug status, and its main patent runs to February 2036 before any extension.²

The bear case, strongest point first. The FDA rejected the core evidence a year ago, and the 8-K does not show what new data answer its concerns. A panel can vote against a drug, and the FDA can still delay or say no.¹ Even an approval sends a 35% approval payment and a cut of sales to the lender, and a launch needs a sales force the company lacks. The SK cash depends on a closing that had not happened as of the last filing on it.² A securities class action over past troriluzole statements is also pending, and Biohaven moved to dismiss it on May 18, 2026.³

Biohaven's own goals for the coming months lie mostly outside troriluzole. It expects topline results from the RISE 3 epilepsy trial of opakalim, and from a roughly 150-patient obesity study of taldefgrobep, in the second half of 2026.¹ The company also says Ono's $20 million milestone is anticipated within a year.²

What would prove the bullish read wrong, and when we will know: the panel's date and vote, due to be set in the near term; the March 1, 2027 audit deadline; and the goal date in the first quarter of 2027.¹ A negative panel vote, a longer review or a second rejection letter would each undercut today's move. A failed SK closing would reopen the funding question before any of those.²

The FDA has not yet set the advisory panel's date, and the 8-K gives only the quarter of the goal date, not a day.

The 8-K says the refiling included new positive supportive analyses but does not say what they measure or whether they add patients.

The last filing on the deal, from September 10, 2026, said the companies were still completing the required antitrust filing; no later filing reports a closing or the $350 million payment.

The Ono agreement makes the upfront payable a redacted number of business days after an invoice, and no filing says the money has arrived.

No filing gives Biohaven's cash after June 30, 2026; at the first-half pace of about $96 million a quarter, roughly $172 million would have remained at the end of the third quarter before any new share sales.