Cougar Biotechnology founder Alan H. Auerbach’s latest cancer treatment venture, Puma Biotechnology, has completed the last stage of a $60 million private financing.

The Los Angeles early-stage company said on Wednesday that it sold about 1.3 million shares of common stock to accredited investors at $3.75 per share, for gross proceeds of nearly $5 million. The shares are not publicly traded.

Proceeds will be used primarily to fund clinical development of a potential breast cancer treatment, oral neratinib, which was licensed from Pfizer Inc. The company’s strategy is to license technologies that have previously been tested in clinical trials. That provides additional security to investors of a drug’s potential usefulness and safety, before they commit capital to the drug’s development.

The company did not identify specific investors in the latest round, but shareholders in the first $55 million round included Adage Capital Partners, Brookside Capital, H&Q Healthcare Investors, H&Q Life Science Investors, and T. Rowe Price Associates.

Johnson & Johnson in July 2009 paid $894 million to acquire Auerbach’s Cougar Biotechnology, which at the time was in late-stage trials on a vaccine for prostate cancer. Auerbach, a former biotech senior research analyst at Wells Fargo Securities, formed Cougar in 2003.