Shares of UniQure, the Netherlands-based gene therapy developer at the center of an unusual, high-stakes standoff with the Food and Drug Administration, spiked Monday morning, likely in response to the planned departure of a top agency official who has opposed the company and the ways in which genetic medicines are reviewed.

On Friday, the FDA disclosed that Vinay Prasad, who last May began leading the division that reviews vaccines as well as cell and gene therapies, would be leaving the agency. It’s his second departure in less than a year, as Prasad had stepped back for a few weeks last summer after a major dispute between the FDA and Sarepta Therapeutics that angered high-profile conservatives.

Prasad was a staunch critic of his predecessor Peter Marks, who received both praise and pushback for championing regulatory flexibility as he oversaw the review of COVID-19 vaccines and dozens of cell and gene therapies. During his short tenure, Prasad established stricter approval guidelines for COVID shots. And though he helped outline a new regulatory pathway designed to accelerate the development of treatments for ultra-rare conditions, Prasad has also been directly or tangentially embroiled in a series of surprise delays, rejections and guidance shifts that left drugmakers and industry experts upset and confused about the FDA’s standards.

His planned exit is therefore “a big win for biotech, especially for companies in the rare disease space,” according to Paul Matteis, an analyst at the investment firm Stifel. Genetic medicine developers, which often set their sights on rare diseases, exemplified this, as around two dozen were trading up by late-morning Monday.

Among the top performers was UniQure, whose stock price had been hammered during a prolonged back and forth with the FDA.

Last September, the company unveiled positive results from a mid-stage clinical trial of a Huntington’s disease gene therapy that impressed researchers and investors, and that UniQure believed were strong enough to earn approval. Executives were therefore taken aback in the fall when, after consulting with the FDA for months, agency staff indicated the data likely weren’t sufficient to support a marketing application.

From there, the outlook for UniQure’s therapy, codenamed AMT-130, only got grimmer. During a late February appearance on CNBC, FDA Commissioner Martin Makary defended his agency’s approach to rare disease drug approvals and made comments that some investors interpreted as him specifically disparaging AMT-130. Shortly after, UniQure disclosed that FDA staff had “strongly recommended” it run another study of its therapy before filing for approval — a development Joseph Schwartz, an analyst at Leerink Partners, called a “worst case scenario for many investors.”

Most recently, the FDA took the highly unorthodox step of holding a call between journalists and a high-ranking agency official who spoke about UniQure’s case on the condition of anonymity. Subsequent reports detailed how the official panned AMT-130 and accused UniQure of mischaracterizing its talks with the agency. Many speculated Prasad was the anonymous source. Congressman Jake Auchincloss, D-Mass., posted on social media on Friday that Prasad had, in discussing the case, violated agency rules and federal law.

Makary confirmed just hours later that Prasad would be leaving the agency in April, as he’d finished the work he set out to accomplish.

UniQure’s therapy “has evolved into a symbol of FDA inflexibility, or at the very least FDA inconsistency,” Matteis wrote in a note to clients Monday. “This is not to say that AMT-130 approval .... will be a slam dunk. But it does seem like after the dust settles here, it has become much more likely that [UniQure] will get the product review that they were seemingly promised.”

Analysts appear to agree that the big question facing biotech is who will replace Prasad. “We see this news as a double-edged sword,” wrote Brian Abrahams, of RBC Capital Markets, referring to Prasad’s upcoming exit.

While it could have some “direct positive implications” for developers of biologics or gene therapies, it also “perpetuates the regulatory leadership volatility that has kept companies uncertain about their developmental direction and many investors on the sidelines,” Abrahams wrote. Additionally, the replacement, even if more lenient, “would likely still mirror the overarching views the Agency and Commissioner Makary currently have.”

At Stifel, Matteis and his team anticipate that, with midterms later this year, the Trump administration won't want to pick someone controversial, especially with regard to vaccines.

Josh Schimmer, an analyst at Cantor Fitzgerald, hopes the new head of the FDA’s biologics review division will be somewhere between “dovish” or “hawkish.”

“There are costs to an overly-permissive FDA environment just as there are costs to an overly-restrictive one,” he wrote.