Amgen's (Nasdaq: AMGN ) Xgeva is already approved to prevent bone breaks once a tumor has moved to the bone, but Amgen is hoping to treat prostate patients earlier in the disease cycle, before the tumor moves outside of the prostate region.
Unfortunately, the decision from the Food and Drug Administration, which is expected tomorrow, doesn't look too promising. The FDA advisory panel voted 12-1 against recommending expanding the use of Xgeva into patients whose tumors haven't expanded beyond the primary site.
Xgeva actually passed its clinical trial testing the drug in these earlier patients, but the committee of outside experts didn't think the 4.2-month delay in the onset of bone metastasis justified the side effects.
I can't even see how this binary event is worth buying as a lottery ticket. The FDA sometimes throws out positive recommendations and rejects a drug, but an approval overruling a negative recommendation with such broad a margin would be unprecedented.
Even though tomorrow's letter from the FDA will likely be a rejection, it won't be useless. The agency should lay out what Amgen needs to do if it wants to get Xgeva approved for use in patients earlier in the prostate cancer progression. Exelixis' (Nasdaq: EXEL ) investors should also be paying attention since Exelixis is trying to get cabozantinib approved as a pain treatment for prostate cancer patients, skirting -- at least initially -- the gold standard of overall survival.
If that's what it'll take to get Xgeva approved in an earlier setting, Amgen will have an uphill battle. Delaying the onset of metastasis by more than four months should translate into some benefit, but it might be too small to demonstrate in a reasonably sized trial. Dendreon's (Nasdaq: DNDN ) Provenge, Johnson & Johnson's (NYSE: JNJ ) Zytiga, and Medivation's (Nasdaq: MDVN ) MDV3100 have demonstrated survival benefits, but they were used on patients that already had metastasis and in some cases failed other drugs, so the life expectancy is fairly short. Following patients from the pre-metastasis stage through the end of their life would make for a long trial.
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