INFINITY, MEDIMMUNE REPORT RESULTS FROM GIST TRIAL

Infinity Pharmaceuticals and MedImmune have announced preliminary results from an open-label Phase I clinical study of IPI-504 in patients with Gleevec-resistant metastatic gastrointestinal stromal tumors (GISTs). IPI-504, Infinity's lead oncology drug candidate, is a proprietary small-molecule inhibitor of heat shock protein 90 (Hsp90) that is being jointly developed by Infinity and MedImmune.

This open-label, dose-escalation trial of IPI-504 is being conducted at the Dana-Farber Cancer Institute in Boston. To date, 20 GIST patients have received IPI-504 at dose levels ranging from 90 to 400 mg/m2. IPI-504 is administered to patients on days one, four, eight and 11, followed by 10 days off treatment, in a 21-day cycle. Patients included in the study were heavily pretreated, and nearly all had failed prior therapy with Sutent as well as Gleevec, two approved therapies for the treatment of GIST.

IPI-504 has been well-tolerated to date at all dose levels tested, and a maximum tolerated dose has not yet been identified. Investigators have observed evidence of biological activity for IPI-504 using positron emission tomography (PET) imaging. In seven of 17 evaluated patients, PET scans revealed a decrease in tumor uptake of 18-fluorodeoxyglucose, an imaging agent used to measure metabolic activity, in response to IPI-504 administration. In some cases, a rebound in tumor activity was observed during the time off treatment, followed by a decrease in tumor activity upon re-administration of IPI-504 in the next cycle. This pattern of tumor response appears to demonstrate biological activity of IPI-504. In addition to the observed PET responses, six of 15 evaluated patients received five or more cycles of therapy with IPI-504.