Wednesday, January 22, 2020 MAC25, A Randomized, Double-Blind, Phase III Trial of Paclitaxel/Trastuzumab/Pertuzumab with Atezolizumab or Placebo in First-Line HER2 Positive Metastatic Breast Cancer, has been centrally activated. This randomized phase III trial studies how well paclitaxel, trastuzumab, and pertuzumab with or without atezolizumab works in treating patients with breast cancer that has spread to other parts of the body (metastatic). Drugs used in chemotherapy, such as paclitaxel, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Trastuzumab is a form of "targeted therapy" because it works by attaching itself to specific molecules (receptors) on the surface of cancer cells, known as HER2 receptors. When trastuzumab attaches to HER2 receptors, the signals that tell the cells to grow are blocked and the cancer cell may be marked for destruction by the body's immune system. Monoclonal antibodies, such as pertuzumab, may interfere with the ability of cancer cells to grow and spread. Immunotherapy with monoclonal antibodies, such as atezolizumab, may induce changes in body's immune system and may interfere with the ability of tumor cells to grow and spread. It is not yet known whether giving paclitaxel, trastuzumab, and pertuzumab with or without atezolizumab may kill more tumor cells. Objectives: The primary objective is to determine whether the addition of atezolizumab to a regimen of paclitaxel, pertuzumab, and trastuzumab will improve the progression-free survival, assessed by investigator using RECIST 1.1 criteria, relative to a regimen of paclitaxel, pertuzumab, trastuzumab, and placebo in patients with newly documented HER2-positive measurable metastatic breast cancer. Secondary objectives include determining whether the addition of atezolizumab to a regimen of paclitaxel, pertuzumab, and trastuzumab will: improve the overall survival relative to a regimen of paclitaxel, pertuzumab, trastuzumab, and placebo; improve the overall objective response, assessed by investigator using RECIST 1.1 criteria, relative to a regimen of paclitaxel, pertuzumab, trastuzumab, and placebo; improve PFS, OR, and/or duration of objective response assessed by retrospective blinded central review using RECIST 1.1 criteria, relative to a regimen of paclitaxel, pertuzumab, trastuzuma and placebo. For more information please visit the CCTG MAC25 trial page.
