The FDA's expert advisors didn't buy Amgen's ($AMGN) argument for earlier use of its bone drug Xgeva in prostate cancer patients. The idea: Treat advanced prostate cancer patients with Xgeva to prevent or delay the disease's spread to the bone. The data: Patients who took Xgeva saw bone tumors crop up an average of 4.2 months later than those on placebo did. Overall survival time didn't differ. The vote: 12-1 against the new use.
The key issues appear to be timing and side effects. Xgeva is already approved to delay fractures and stave off tumor growth in patients who have developed bone metastases. Why not wait until the tumors develop to treat with Xgeva, panelists asked, especially since roughly one in 15 patients in the trial developed osteonecrosis of the jaw? "This isn't a question of whether this drug works," the panel chair, Wyndham Wilson, said. "It's a question of when is the most effective time to give it."
Wilson suggested the most helpful comparison wouldn't be Xgeva versus placebo, both given early on before bone metastases occur. Rather, Amgen should evaluate Xgeva use in preventing metastases versus its use in handling them once they've arisen. But Amgen's Sean Harper pointed out some Xgeva patients went 7.5 months without developing bone tumors, Bloomberg reports, and bone metastases are quite painful.
The FDA is due to decide on the new use by April 26. The agency doesn't always take its advisory committees' advice, although it usually does, and FDA staffers expressed their own reservations about Amgen's application. Analysts' viewpoints on the indication were mixed; some said revenue estimates on Xgeva had already mostly discounted the prospect of prophylactic use, while others figure their peak sales predictions would be cut by as much as $1 billion if the indication doesn't come through.