Saol Therapeutics is the latest biotech to resubmit for approval of a drug rejected under former FDA Commissioner Marty Makary, following REGENXBIO and Replimune.
Ten months ago, Saol Therapeutics was in a bind after the FDA rejected the application for its ultra-rare disease drug. To address the agency’s concerns would take “several years” and require “significant financial resources,” the Georgia and Bermuda–based biotech said in September 2025. Now, Saol’s fortunes appear to have changed, as the company resubmitted the candidate on Tuesday.
The filing follows Type A and Type C meetings with the FDA. During the Type A meeting in December, Saol—pronounced “Sail”—asked to “directly” resubmit the application for SL1009, but the FDA advised that it would be quicker to first participate in a Type C meeting so both parties could agree on the content of the submission package, CEO Dave Penake recalled. “We’re hoping that that leads to a faster review,” he told BioSpace.
SL1009, also known as DCA, is being developed for pyruvate dehydrogenase complex deficiency, a life-threatening mitochondrial disease for which there are no FDA-approved treatments. During the meetings, “the FDA provided guidance recommending additional survival analyses to support the application,” according to Saol’s announcement. Because the company’s resubmission includes additional data—such as information from its emergency Investigational New Drug (IND) programs—Penake said the review period is supposed to be six months—“if they go by the book.”
However, he said, “I think the agency has not always been bound by the standard timeframes lately, which I think is a good thing.”
It wouldn’t be the first time the agency has expedited a review of a previously rejected therapy.
Saol’s candidate was among a spate of rare disease rejections by the FDA in the second half of 2025. Other biotechs caught off-guard by rejections were Capricor Therapeutics, Biohaven and Replimune. Capricor’s Duchenne muscular dystrophy cardiomyopathy cell therapy deramiocel and Replimune’s advanced melanoma drug RP1 have both been resubmitted and now have new target action dates this summer. In Replimune’s case, the decision date will arrive less than two months after the agency accepted the application.
Saol submitted its application on June 30 and expects the FDA to set a target action date prior to July 30, Penake said.
If the agency does accept Saol’s new filing, SL1009 will be the latest therapy to benefit from the FDA’s newfound flexibility after the spring departures of former Commissioner Marty Makary and Center for Biologics Research and Evaluation (CBER) director Vinay Prasad. In addition to Capricor and Replimune, uniQure has also rebounded from a regulatory rebuff delivered under Makary, announcing plans last month to submit for approval of its Huntington’s disease gene therapy in the third quarter after the FDA reversed course on requiring a sham surgery–controlled Phase 3 trial. UniQure was quickly followed by REGENXBIO, which revealed it would refile for approval of a recently rejected Hunter syndrome gene therapy, also in Q3, after the FDA deemed the company’s existing data sufficient to support an accelerated filing.
“What I would assume is that the vast majority of the other products that have gone through this have really tried to deal head on with the issues,” Penake said of the recent rush of seeming regulatory reversals. “The agency may have been more receptive under different folks who were operating it, or maybe it was the same, the issues just needed to be addressed.”
Penake believes Saol has addressed the FDA’s concerns, which the company did not reveal at the time of the complete response letter. The new survival data includes 36 natural history–matched pairs—compared to around 28 in the initial submission—and an additional 18 months of data demonstrating a 91% reduction in the risk of death with SL1009, he said.
The United Mitochondrial Disease Foundation at the time of the September CRL issued a dire warning. The FDA’s rejection of SL1009, according to the group, could delay access to life-saving therapies, in turn leading to “irreversible damage—or even death.”
Regarding the resubmission, Penake said, “We’re just excited to be working with the agency and helping these kids.”
