Phase 2 Study Shows Novel Tyrosine Kinase Inhibitor Effective in Metastatic Breast Cancer

Puma Biotechnology announced results from a Phase 2 clinical trial of the investigational drug PB272 (neratinib) in patients with HER2+ metastatic breast cancer. PB272 is an oral potent irreversible tyrosine kinase inhibitor.

The study enrolled patients with HER2+ metastatic breast cancer and disease progression on trastuzumab (Herceptin; Genentech). Patients in the study received a median of 3 prior cytotoxic regimens (range 1–12 prior regimens) before entering the trial. Of the 27 patients enrolled in the trial, 14 patients (52%) had either estrogen receptor positive disease or progesterone receptor positive disease. In addition, 20 patients (74%) had visceral metastases and 3 patients (11%) had brain metastases. Patients were administered PB272 at a dose of 240mg per day in combination with temsirolimus given at a dose of 8mg weekly.

For the 27 evaluable patients, 12 patients (44%) experienced a partial response (PR) and 1 patient (4%) experienced prolonged stable disease (SD) for >6 months. Patients who experienced a partial response to the combination of neratinib plus temsirolimus demonstrated a maximum change in the size of their target lesions of between 33%–83%. Clinical benefit was seen in patients previously treated with trastuzumab as well as lapatinib (Tykerb; GlaxoSmithKline), T-DM1 and pertuzumab (Perjeta; Genentech). The median progression free survival of the 27 evaluable patients was seen to be 18 weeks (4.2 months).

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