This trial is designed to explore a new schedule of delivery with PX-12 given as a 24-hour infusion every two weeks, and will evaluate the safety, pharmacokinetic profile, and anti-tumor activity of the drug. The study is to be conducted by Dr Tomislav Dragovich at the Arizona Cancer Center in Tucson, Ariz.
PX-12 is a small molecule designed to inhibit thioredoxin, a protein which can stimulate cell growth and block apoptosis. The increased thioredoxin levels in cancer cells have been linked to the aggressive proliferation of solid tumors including colon, lung and gastric cancers.
According to the company, PX-12 has shown excellent activity in animal models against these tumors as well as breast and prostate cancers.
In an initial phase I trial of the drug, 38 patients with advanced metastatic cancer were given PX-12 as a one or three hour infusion daily for five days every three weeks. The trial established that PX-12 was well tolerated up to doses of 226 mg/m2 and produced a significant decrease in plasma concentrations of the target protein, thioredoxin, especially when delivered by the three hour infusion. Seven of the 38 patients achieved stable disease of up to 322 days.
“It is hoped that a prolonged infusion of PX-12 will result in extended target inhibition with a well-tolerated schedule of delivery,” said Dr Lynn Kirkpatrick, CEO of Prolx Pharmaceuticals. “We look forward to exploring this novel approach to treating gastrointestinal cancers as well as evaluating PX-12 in other disease settings.”