Our lead heat shock protein 90 (Hsp90) inhibitor, retastpimycin, also known as IPI-504, is a small molecule drug candidate being developed jointly by Infinity and MedImmune, a division of AstraZeneca. The drug product, retaspimycin hydrochloride is delivered as an intravenous infusion.

Retaspimycin hydrocloride has been well-tolerated and has shown promising biological activity in clinical trials in patients with metastatic and/or unresectable gastrointestinal stromal tumors (GIST) and patients with advanced non-small cell lung cancer (NSCLC). Retaspimycin hydrochloride is also being evaluated in a Phase 2 study in patients with hormone-refractory prostate cancer (HRPC) and in a Phase 1b study in combination with Taxotere® in patients with advanced solid tumors. Additional clinical trials for retaspimycin hydrochloride as both a single agent and in combination with marketed therapies are planned.

Data from clinical trials with retaspimycin hydrochloride are available in the publication archive.

Retaspimycin has been shown in preclinical studies to inhibit Hsp90 potently and selectively, thereby killing cancer cells. In these preclinical studies, retaspimycin has demonstrated a broad potential to treat cancer as a single agent as well as in combination with existing anti-cancer drugs. In addition, retaspimycin preferentially targets and accumulates in tumor tissues. For these reasons, we believe that retaspimycin has broad potential for the treatment of patients with a wide variety of solid and hematological tumors, including cancers that are resistant to other drugs.

In October, Infinity was issued a patent (U.S. Patent No. 7,282,493) by the United States Patent and Trademark Office broadly covering retaspmimycin and other related molecules useful for treating cancer. The patent includes composition of matter, pharmaceutical composition, method of treatment, and synthetic method claims.