April 7 (Reuters) - A mid-stage trial of Puma Biotechnology's experimental drug neratinib showed that it was more effective, given before surgery, than Herceptin, the Roche drug commonly used in women with a type of breast cancer fueled by a protein called HER2.
The trial involved treating 193 newly diagnosed patients prior to surgery. About 39 percent of HER2 patients given a combination of neratinib and chemotherapy achieved a "pathologic complete response," compared with 23 percent of women treated with chemo and Herceptin.
Pathologic complete response, or pCR, means there is no remaining evidence of the tumor in the breast or lymph nodes.
The trial also found that the experimental drug resulted in a higher rate of pCR, 45 percent, than standard care, 29 percent, in women with tumors for which genetic testing indicated a high probability that their cancer would return.
Alan Auerbach, Puma's chief executive officer, said the company is in the process of designing Phase 3 trials of neratinib in both HER2-positive patients and in patients with a high risk of breast cancer recurrence.
The drug, which was licensed by Puma from Pfizer Inc , is also being studied in a range of other cancer indications.
In the Phase 2 trial, due to be presented on Monday in San Diego at a meeting of the American Association for Cancer Research, patients were stratified into 10 different groups, based on hormone sensitivity and other factors.
About 25 percent of breast cancers are HER2 positive.
The Phase 2 trial used "adaptive randomization," meaning patients entering the study were assigned to treatment regimens that were performing better in patients with the same cancer subtype.
Auerbach said neratinib, a pill, has a different mechanism of action than Herceptin, a bioengineered antibody given by infusion, as well as Perjeta, a newer Roche drug approved for use in combination with Herceptin.
As a result, HER2-positive patients could potentially be treated with a regimen of chemotherapy, plus Herceptin, Perjeta and neratinib, he said.
Breast cancer is the most common cancer among women, with about 1.4 million new cases diagnosed each year and more than 450,000 women dying of the disease annually, according to the World Health Organization.
(Reporting by Deena Beasley in Los Angeles; Editing by Lisa Shumaker)