Puma slides on detailed I-SPY 2 data

Puma Biotechnology Inc. (NYSE:PBYI) fell $6.08 to $80.86 on Tuesday after reporting detailed efficacy and safety data for neratinib (PB272) from the adaptive Phase II I-SPY 2 trial evaluating neoadjuvant breast cancer therapies. Tuesday's move brings to $25.55 (24%) Puma's loss since reporting the data, which translates to a two-day loss in market cap of $770 million for a $2.4 billion valuation.

At the American Association for Cancer Research meeting Puma said that in patients with HER2-positive/hormone receptor-negative breast cancer, oral neratinib plus paclitaxel followed by doxorubicin and cyclophosphamide led to an estimated pathologic complete response (pCR) rate, the primary endpoint, of 55.6% vs. 32.6% for standard therapy consisting of paclitaxel plus Herceptin trastuzumab followed by chemotherapy. The most frequently observed severe adverse event was diarrhea, with grade 3/4 diarrhea in 39% of patients in the neratinib-treated arm vs. 4% in the control arm. ...