Infinity Drug Slows Spread of Deadly Stomach Cancer—FDA Clears Accelerated Trial

Here’s something you don’t see every day from the FDA. The U.S. drug regulator is allowing Infinity Pharmaceuticals to skip the usual second phase of clinical trials, after an early study showed one of its drug candidates stabilized tumors for two-thirds of patients with a deadly stomach cancer.

The move enables the Cambridge, MA-based company to leapfrog into the final stage of development with the drug, IPI-504, this summer. If the trial succeeds, Infinity will shave two years off its original timeline to bring the drug to the market.

The accelerated push comes after an early-stage study of 36 patients found Infinity’s drug stabilized tumors for about two-thirds of people with inoperable gastrointestinal stromal tumors spreading through the body, the company said today in an e-mailed statement. The drug kept the disease from further advancing for a median time of 12 weeks, for patients who have failed on all other treatments.

Infinity made the announcement today at the American Society of Clinical Oncology in Chicago, a gathering that draws 30,000 of the sharpest minds in the cancer field. Andrew Wagner, an oncologist at the Dana-Farber Cancer Institute, presented detailed results. If the finding can be repeated in a study of 200 patients, then Infinity and partner AstraZeneca could have a new way of treating a disease that affects 10,000 to 15,000 people in the U.S. each year.

“This is as good as it gets in Phase I, with robust data in this patient population,” said Julian Adams, Infinity’s chief scientific officer, in a telephone interview.

Infinity’s product is designed to block Hsp-90, a protein that scientists say works like a chaperone to cancer-causing proteins like c-Kit, EGFR, and HER2. The Hsp-90 protein is thought to support and stabilize those tumor growth proteins. Since other drugs are already aimed at those targets, an Hsp-90 blocker may be useful in combination treatment, Adams said. The combo approach has potential against multiple forms of cancer, including lung and prostate tumors, which are in the company’s development plan.

The Infinity drug, like any other, has its drawbacks. It was linked to nausea, vomiting, fatigue, and headaches, all of which were considered mild and reversible, Adams said. Patients had to take the drug intravenously twice weekly for two weeks, then take a week off, a dosing schedule that the company spent two years honing to strike the best balance between effectiveness and safety. The small trial didn’t have a control arm, so there’s no way of directly comparing the result to any other treatment approach.

Patients with gastrointestinal stromal tumors have already gotten some good news in recent years, with progress coming from Novartis’ Gleevec and Pfizer’s Sutent, which both block tumor growth signals from what are known as tyrosine kinases. Those drugs have been shown to shrink tumors, although that approach has already run into the law of diminishing returns, because cancer cells develop resistance to the treatments. That creates an opportunity for drugs, like Infinity’s, with a different way of working, Adams said.

The final, Phase III clinical trial of 200 patients will provide a definitive answer on whether IPI-504 offers a real advance worthy of approval for the U.S. market, Adams said. It is scheduled to start before the end of September, at 50 sites worldwide. Patients will be randomly assigned to the drug or to a placebo treatment, although patients in the latter group may also get the drug if their disease spreads, Infinity said. The FDA has signed off on the trial design.

The FDA also agreed that if Infinity reaches its main goal of slowing the spread of cancer, then Infinity can apply for approval of the drug. The process of recruiting patients, observing them for months, analyzing the results, and submitting them to the FDA should take two to three years, Adams said.

If Infinity succeeds, it will have the first Hsp-90 blocker against gastrointestinal stromal tumors, and it may be the first drug of its kind against any type of cancer, Adams said. The company’s main rival, Kosan Biosciences of Hayward, CA, is developing a different Hsp-90 blocker for multiple myeloma, a cancer of the bone marrow. This week, Kosan agreed to be acquired by Bristol-Myers Squibb for $190 million.

If Infinity’s drug reaches its goal against gastrointestinal stromal tumors, then it could be worth a whole lot more than that.

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