117mSn-HTC (Homogeneous Tin Colloid)

Developer: Exubrion Therapeutics (currently available for veterinary use only)

Description

^117mSn-HTC, also known as ^117mSn-Tin Colloid, ^117mSn-Homogeneous Tin-117m Colloid, or Synovetin OA™, is a radiopharmaceutical agent developed by Exubrion Therapeutics, a subsidiary of Serene LLC. The compound is marketed under the brand name Synovetin OA™ for veterinary use as a treatment for osteoarthritis in animals. It is also being developed for potential human clinical applications by Convetra, another subsidiary of Serene LLC.

^117mSn-HTC is composed of colloidal particles of ^117mSn (tin-117m) within a controlled particle size distribution. This design ensures that, once injected into a joint, the particles remain localized and do not migrate beyond the injection site. The product functions as a radiosynovectomy (RSO) agent, which means it delivers targeted radiation therapy to inflamed synovial tissue within the joint, helping to reduce pain and inflammation associated with arthritis. The veterinary version of this product was officially launched in June 2018 and commercialized through Exubrion, which was spun off as a separate entity in April 2019.

Clinical Applications

^117mSn-HTC is classified as a nuclear veterinary drug and is primarily used for the treatment of osteoarthritis in animals. The product has demonstrated efficacy in treating osteoarthritis in dogs, and studies have shown that Synovetin OA™, when injected into canine elbow joints, is selectively phagocytosed by inflammatory macrophages. This uptake occurs without causing adverse effects to nearby synoviocytes, cartilage, bone, or connective tissues.

The primary veterinary applications of ^117mSn-HTC include treatment of osteoarthritis in dogs, but it is also being explored for use in cats, horses, camels, and dromedaries. The localized nature of the treatment makes it an attractive alternative to more invasive surgical procedures.

Stage of Development

^117mSn-HTC has been fully developed and commercialized as a veterinary product for the treatment of osteoarthritis in dogs and other animals. The product is manufactured under Good Laboratory Practice (GLP) and Current Good Manufacturing Practice (cGMP) standards, ensuring it meets high regulatory and quality assurance standards for veterinary applications.

On the human side, Convetra is preparing for Phase I clinical trials to test the product’s potential for use in human radiosynovectomy (RSO) treatments. This strategic development plan leverages the existing infrastructure and production processes already established for the veterinary product. Revenue generated from the veterinary version is being used to support human drug development, accelerating the transition to clinical trials.

Comments

^117mSn-HTC is a pioneering product within the field of veterinary radiotherapy, offering a non-surgical solution for the treatment of osteoarthritis in animals. Its unique mechanism of action, based on the uptake of radiolabeled particles by inflammatory macrophages, ensures targeted treatment while preserving the health of surrounding tissues.

The development strategy followed by Serene LLC is noteworthy. By focusing first on the veterinary market, the company established a commercial revenue stream that supports the future development of the drug for human clinical use. This approach reduces financial risk and accelerates the path to human clinical trials. Given the success observed in veterinary applications, the potential for human use of ^117mSn-HTC as an RSO agent appears promising. The launch of human clinical trials in Canada marks a significant step toward regulatory approval for human use, which could ultimately expand its market presence and application scope.