Cougar Biotechnology Inc. said its first-quarter loss grew as late-stage clinical trials of its experimental prostate cancer therapies increased the company? research and development costs.

The Los Angeles company late Monday reported a net loss of $23.3 million (-$1.12 per share), compared with a loss of $6.4 million (-31 cents) a year ago. The company, which has no products on the market, reported no revenue in either quarter.

Analysts surveyed by Thomson Reuters on average expected a loss of 94 cents per share.

Operating expenses rose 48 percent to $23.5 million. A drug candidate called CB7630 is in late-stage development for prostate cancer in patients who have failed chemotherapy. The company is also studying the drug for use in prostate cancer patients who have not yet had chemotherapy.

?e continue to be committed to maintaining our focus on creating shareholder value during 2009 and we look forward to continuing to aggressively advance our clinical program for CB7630,?Chief Executive Alan H. Auerbach said in a statement.

Cougar shares were up 24 cents, or less than 1 percent, to $35.24 in midday trading on the Nasdaq.