Saol Therapeutics is seeking to position its drug candidate SL1009 as a model case for the U.S. Food and Drug Administration’s (FDA) new Rare Disease Evidence Principles (RDEP) framework, following a recent regulatory setback.
In September, Saol announced that the FDA had issued a complete response letter (CRL) for SL1009, an oral formulation of sodium dichloroacetate designed to treat pyruvate dehydrogenase complex deficiency (PDCD) in children. The CRL indicated that an additional adequate and well-controlled clinical trial would be required for approval.
Saol CEO Dave Penake told BioSpace, “The letter suggested that we would need to do an additional adequate and well controlled clinical trial, and that’s not feasible to be done by our company and in this patient population.” He added, “Our clear goal is to find a path forward that does not involve the need to conduct another trial and bring the FDA onboard.”
The company has been granted a Type A meeting with the FDA scheduled for December 18. At this meeting, Saol plans to present new analyses not previously reviewed by the agency. These include expanded data on functional benefits such as longer treatment duration, survival benefit, mechanistic support, safety information, and over 100 patient-years of exposure.
According to Saol’s press release, the company “believes these data reinforce the risk/benefit of SL1009 and demonstrate how the totality of evidence satisfies the FDA’s proposed Rare Disease Evidence Principles.”
The RDEP framework was introduced by the FDA on September 3 with the aim of streamlining approvals for therapies targeting ultra-rare diseases. PDCD affects fewer than 1,000 people in the United States. The RDEP program allows regulators to consider additional supportive data when reviewing products intended for very small patient populations.
Penake explained: “In PDCD, there’s a genetic defect that causes an enzyme deficiency. The drug that we use in SL1009, it’s very targeted, and it actually restores the enzyme activity. The way we see the plausible mechanism [pathway] in RDEP is that it’s very targeted for populations like this, too small to maybe study in a reasonably coherent manner, a very clear cause of the disease, a very targeted mechanism that corrects the disease.”
PDCD leads to lactic acid buildup resulting in complications such as nausea, vomiting, severe breathing problems, neurological impairments and abnormal heartbeat. Most patients do not survive beyond early childhood. There are currently no approved treatments available for PDCD patients.
SL1009 is described by Penake as “a very targeted [treatment] and appears to be an effective one,” adding: “so we certainly hope that we can find a good path forward.”
