We develop transformative, cost effective therapies for cancer that will serve a worldwide market.
Hal Crow, Chairman
Tosk was founded to discover and develop new drugs for cancer and other conditions using non-mammalian animal species as discovery tools for human diseases. These efforts evolved into two proprietary drug discovery platforms that use the common fruit fly (Drosophila melanogaster) as an experimental model to find new drugs.

The company uses one application of this technology, known as the Side Effect Fly™, to discover agents that prevent the adverse effects of existing drugs. The first applications of this technology are for widely used chemotherapeutics and radiation therapy. Tosk’s most advanced drug, TK-90 for mucositis side effect therapy and preventation, has recently completed proof of concept testing in human clinical studies with excellent results. Tosk’s second drug, TK-39 for cardiotoxicity side effect prevention, is undergoing the final step in preclinical testing needed to enter human studies.
Tosk’s second drug discovery platform, known as the Genetically Modified Fly™, uses Drosophila implanted with human cancer genes. The first application of this technology targets the human KRAS oncogene that promotes growth in as many as 30% of all cancers and that renders an important class of cancer drugs known as EGFR inhibitors ineffective in many patients.
Unlike companies pursuing expensive, end-of-life therapies, Tosk develops low-cost, small molecule drugs designed to improve outcomes for cancer patients on a worldwide basis, not just in affluent countries.