On November 13, 2014 Puma Biotechnology reported top line results from a Phase II clinical trial of Puma’s investigational drug PB272 (neratinib) for the treatment of first-line HER2-positive locally recurrent or metastatic breast cancer (NEfERTT trial) (Filing 8-K , Puma Biotechnology, NOV 13, 2014, View Source [SID:1234500962]). The NEfERTT trial is a randomized, two-arm Phase II trial of neratinib plus the anticancer drug paclitaxel versus trastuzumab (Herceptin) plus paclitaxel as a first-line treatment for HER2- positive locally recurrent or metastatic breast cancer.
The NEfERTT trial enrolled 479 patients in 33 countries with locally recurrent or metastatic breast cancer who had not received prior anticancer therapy for locally recurrent or metastatic disease. Patients were randomized to receive first-line treatment with either paclitaxel plus neratinib or paclitaxel plus trastuzumab. The primary endpoint of the trial was progression free survival (PFS). The secondary endpoints of the study included objective response rate (ORR) and the incidence of central nervous system (CNS) metastases, including brain metastases.
The safety results of the study showed that the most frequently observed adverse event for the patients who received the combination of paclitaxel plus neratinib was diarrhea, with approximately 30% of the patients experiencing grade 3 diarrhea. The rate of grade 3 diarrhea in the patients who received the combination of paclitaxel plus trastuzumab was approximately 4%. Patients who received neratinib in this trial did not receive any prophylaxis with antidiarrheal agents to prevent the neratinib related diarrhea. Puma’s recently reported clinical data from a Phase II trial of neratinib in HER2 mutated non-small cell lung cancer demonstrated that the use of high dose loperamide greatly reduces the rate of grade 3 diarrhea with neratinib. In that trial the grade 3 diarrhea rate was 8% in the patients who received neratinib monotherapy. In all of its current ongoing studies Puma is instituting the use of high dose loperamide in order to continue to reduce the neratinib related diarrhea.
The primary endpoint of the NEfERTT trial was progression free survival. The results of the trial demonstrated that the progression free survival for the patients who received the combination of paclitaxel plus neratinib was 16.6 months and the progression free survival for the patients who received the combination of paclitaxel plus trastuzumab was 16.7 months (p=0.35). The objective response rate in the trial for the patients who received the combination of paclitaxel plus neratinib was 74.8% and the objective response rate for the patients who received the combination of paclitaxel plus trastuzumab was 75.1% (p=0.94). These results did not demonstrate a statistically significant difference between the PFS and ORR results for the two treatment arms, which was consistent with expectations.
With respect to the incidence of central nervous system metastases (e.g., brain metastases), treatment with the combination of paclitaxel plus neratinib resulted in a 52.6% reduction in the incidence of CNS metastases compared to the incidence of CNS metastases in patients who received the combination of paclitaxel plus trastuzumab. The incidence of CNS metastases was 7.4% in the patients who received paclitaxel plus neratinib, while the incidence of CNS metastases in the patients who received the combination of paclitaxel plus trastuzumab was 15.6% (p=0.006). These results reflect a statistically significant difference between the two treatment arms.
Full results of the NEfERTT trial for PB272 will be presented at a future scientific meeting in 2015.
“We are very pleased with the results of the NEfERTT trial with neratinib,” said Alan H. Auerbach, Chief Executive Officer and President. “As expected, there was no statistically significant difference in progression free survival and objective response rate for the paclitaxel plus neratinib arm compared to the paclitaxel plus trastuzumab arm. However, the paclitaxel plus neratinib arm showed a statistically significant decrease in the incidence of CNS metastases compared to the paclitaxel plus trastuzumab arm. This represents the first randomized trial with a HER2 targeted agent that has shown a statistically significant reduction in the incidence of CNS metastases, which we believe provides a meaningful point of differentiation for neratinib in the treatment of HER2 positive breast cancer. While the development of other HER2 targeted drugs has produced a clinically meaningful benefit to patients with HER2 positive breast cancer, these drugs have had little impact on CNS metastases. As a result, we believe that there remains an unmet clinical need for reducing the incidence of CNS metastases and the results of the NEfERTT study demonstrate that we may be able to provide this type of improvement with neratinib.”