24 May 2013 - 24 May 2013 - US Merrimack Pharmaceuticals Inc (NASDAQ:MACK) said on Thursday it had wrapped up enrolment in a Phase II study of its fully human monoclonal antibody targeting ErbB3, MM-121, in combination with exemestane in postmenopausal women with locally advanced or metastatic estrogen receptor positive (ER+) and/or progesterone receptor positive (PR+), HER2-negative breast cancer.

The company is developing the compound together with French Sanofi (EPA:SAN).

Merrimack's senior medical director Dr Akos Czibere said that the company is hopeful that the combination of MM-121 with exemestane can block the ErbB3 pathway, which the firm believes promotes exemestane resistance and, ultimately, prevent the cancer from advancing.

Top line results from this study are expected in the second half of the current year.