Syndax Pharmaceuticals has partnered with Roche Group member Genentech to begin a Phase Ib/II clinical trial of entinostat in combination with atezolizumab (Tecentriq) to treat the second-line hormone receptor positive, human epidermal growth factor receptor 2 negative (HR+, HER2-) metastatic type of breast cancer.

The open-label, multicentre, randomised trial seeks to evaluate the efficacy, safety, and pharmacokinetics of immunotherapy combination in HR+, HER2- metastatic breast cancer.

The study aims to enrol patients with metastatic HR+, HER2- breast cancer who have experienced disease progression during or following first-line therapy.

It will be carried out by Genentech under Roche’s new cancer immunotherapy development platform MORPHEUS, which is a Phase Ib/II adaptive platform to develop combinations of cancer immunotherapies rapidly.

“While checkpoint inhibitors have shown initial promise in triple-negative breast cancer, there is a clear need to augment the effectiveness of such therapies in the setting of HR+, HER2- breast cancer.”

Syndax Pharmaceuticals CEO Briggs Morrison said: “This collaboration represents further validation of the ongoing interest to test the potential ability of Syndax’s entinostat to enhance the effectiveness of an immuno-oncology therapy in an area of unmet medical need.

“While checkpoint inhibitors have shown initial promise in triple-negative breast cancer, there is a clear need to augment the effectiveness of such therapies in the setting of HR+, HER2- breast cancer.”

Syndax added that its entinostat is an oral, small molecule, class I HDAC inhibitor, while Genentech’s atezolizumab (TECENTRIQ) is a programmed cell death ligand 1 (PD-L1) blocking antibody.

In 2015, Syndax partnered with Genentech to conduct a Phase Ib/II trial to examine the safety, tolerability and clinical activity of entinostat in combination with TECENTRIQ in triple-negative breast cancer.

The ENCORE 602 trial is expected to complete patient enrolment forits Phase II portion in the first half of this year.