Puma down on Phase III neratinib data

Puma Biotechnology Inc. (NYSE:PBYI) sank $44.72 (21%) to $165 in after-hours trading Wednesday after an abstract released ahead of the American Society of Clinical Oncology meeting revealed details from the Phase III ExteNET trial of neratinib. The trial studied neratinib as an adjuvant treatment for HER-2 positive early stage breast cancer. In patients who had previously received adjuvant chemotherapy and Herceptin trastuzumab from the Genentech Inc. unit of Roche (SIX:ROG; OTCQX:RHHBY). The data showed a statistically significant yet modest disease-free survival (DFS) benefit and included rates of adverse events, including diarrhea.

The abstract showed that 93.9% of neratinib-treated patients in the study reached invasive DFS at two years, the study's primary endpoint, vs. 91.6% of patients in the placebo arm (HR=0.67; 95% CI: 0.50, 1.91; p=0.0046). ...