J&J's Zytiga gets expanded approval that could double sales

Chalk up an expanded use, and so an expanded market, for Zytiga, Johnson & Johnson's ($JNJ) hot but pricey prostate cancer drug.

The FDA on Monday said it approved Zytiga for treatment in men with late-stage, prostate cancer even before they receive chemotherapy. A study found that it reduced tumor growth and could extend life expectancy about 5 months.

When analysts heard about the pre-chemo data earlier this year, they got out their calculators and projected that if approved it could double sales for the drug. Zytiga, which is marketed by J&J's Janssen Biotech unit, costs $5,500 a month and is considered the leader in its category. It however faces some fierce competition in a hot market category that is projected to hit about $9.1 billion in 2021.

Prostate cancer drug Xtandi from Medivation ($MDVN) and Astellas Pharma is a comer. The drug won approval from the FDA in August and was launched in September. The partners are expected to aggressively push upstream toward the same pre-chemo market that J&J just won for Zytiga.

Xtandi is priced at a premium--$7,450 wholesale for a 30-day supply, or about $85,000 annually--but consultants at Decision Resources expect it to overtake Zytiga, sales-wise. They project that Zytiga will hit peak sales of $1.8 billion by 2015, but forecast Xtandi could reach a peak of $2.2 billion by 2021, even as the overall market continues to grow.

- here's the FDA announcement