Puma Biotech delays breast cancer drug filing about a year, to early 2016; shares slide

Puma Biotechnology said Tuesday that it won't file for marketing approval of an experimental breast cancer drug until early 2016, sending its shares plunging in aftermarket trading.

The company had said it would file for approval of PB272, or neratinib, in the first half of 2015 but it now intends to make that filing in the first quarter of 2016. Puma Biotechnology said it is delaying its application because it will ask the Food and Drug Administration to approve the drug as a treatment for a different form of cancer. It wants to market the drug to treat cancer that has metastasized rather than early-stage cancer.

The Los Angeles company reported positive results from a late-stage trial of the drug in July.

Shares of Puma Biotechnology Inc. dropped $38, or 17 percent, to $187 in aftermarket trading. Its shares have more than doubled in value in 2014, closing at $225 on Tuesday.