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In what must be one of the faster conversions of pivotal results into approved products in quite a while, Medivation's (MDVN) Xtandi has received an FDA nod in post-chemotherapy prostate cancer treatment and is expected to launch later this month.

Shares in the California group rose 8% to a record high of $104.86 Friday on the news, a startling turn of events for a company whose stock was one-tenth that price two years ago in the wake of the disastrous failure of its Alzheimer's disease project Dimebon. Investor exuberance is being buoyed by hope that Xtandi, known generically as enzalutamide, will be successful in the pre-chemo population - where competitor Zytiga hopes to take share; analysts from Wedbush believe 20% of Xtandi's 2013 sales will be off-label in this patient group.

Big boost

Xtandi had an action date of November 22, so the swift approval is a strong affirmation. Forecasts have mushroomed since Medivation and its partner Astellas Pharma stopped the Affirm study early because of evidence of a survival advantage over placebo, and now stand at $1.44bn in 2018 (Medivation roars back to life as prostate cancer drug delivers, November 3, 2011).

Given the need in the post-chemo population - patients who typically have progressed following surgery, androgen deprivation therapy and docetaxel-based chemo - approval is not surprising. Johnson & Johnson's (JNJ) Zytiga was approved last year, based on a survival benefit of about four months; data published earlier this month in the New England Journal of Medicine indicate about a 4.8-month benefit for Xtandi.

However, expanding to pre-chemo treatment regimens is a clear strategic goal for both J&J and Medivation/Astellas. Patients with metastatic disease spend the longest proportion of their lives before cytotoxic chemicals are used, and thus represent a big population; J&J sees 30% of its sales in these patients (Asco - Metastatic prostate cancer space increasingly a battleground, June 4, 2012).

Thus, J&J just last week received priority review for its supplemental NDA for Zytiga plus prednisone in this setting, on the back of data published at ASCO. Data from Medivation and Astellas' Prevail trial in pre-chemotherapy patients could come in 2013 or early 2014, so Xtandi will be chasing hard to catch up to Zytiga's progress.

The loser

In the meantime, Xtandi's partners are conducting the Phase II Terrain trial of the androgen receptor signalling inhibitor to test progression-free survival, a test that features the anti-androgen Casodex as an active comparator. Data from this could be reported next year; positive results should strengthen off-label use before the Prevail data are available.

The growing competition in the space will of course come at the expense of Provenge, Dendreon's innovative autologous immunotherapy that received approval two years ago and has disappointed since(Shifting analyst views highlight industry's bright sparks and damp squibs, August 16, 2012). A place probably still exists for Provenge in treating frail and older patients because it has the fewest toxicity concerns, but an expensive and labour-intensive manufacturing process has restrained its long-term promise.

Xtandi has been the beneficiary of an unusually swift approval, which no doubt only bolsters investor excitement in Medivation. Continued positive news will be necessary to maintain this momentum.

Source: Medivation Gets Surprise Early Approval For Prostate Cancer Pill