The repurposing of approved medications with potential new efficacy in rare diseases is challenging, as these medications are unlikely to be studied and be approved by the FDA for their potential new indication. In PSC, the use of oral vancomycin (OV), an approved and repurposed drug, remains an area of debate in both the clinical and patient communities. There is growing evidence of a clinical benefit with OV treatment for certain PSC patients, especially those with active IBD symptoms. However, there is no definitive study to determine the best approach for using OV in PSC, including which patients will most benefit from OV and what treatment time frame will be most effective. Although there are several randomized clinical trials (RCT) underway, it is unlikely that these will provide a timely answer or address many of the questions that remain about how to best use OV. Because of the lack of RCT data, access to OV remains a significant challenge for many patients.
A recent publication in Digestive Diseases and Sciences (1) provides a rational scientific framework using an “adaptive treatment strategy” for OV in PSC patients. The article highlights an approach that considers current information, presents an algorithm for OV treatment while also acknowledging the risks and challenges. The treatment approach outlined is “adaptive” in two important ways. First, the treatment decisions are based on an individual patient's response. Second, the definitions of response to OV can be adapted and refined as new data become available. A similar approach was taken with the use of UDCA in PSC which led to an adaptive treatment algorithm that was incorporated into most of the clinical guidance and guidelines, despite the lack of a definitive RCT.
There is still work that needs to be done to define treatment response for broad acceptance by the clinicians and payors. However, the authors propose a cogent starting point that can help support access to OV for patients who may benefit from it. We thank the authors for suggesting a practical approach to decision making in treating rare diseases with repurposed drugs such as OV for PSC.
(1) Shah A, Tabibian J, Buness C, Holtman G. An “adaptive treatment strategy” for oral vancomycin in patients with the orphan disease primary sclerosing cholangitis. Digestive Disease and Sciences https://doi.org/10.1007/s10620-024-08497-4