AACR 2015: Investigational PD-L1–Targeted Immunotherapy Safe for Patients With Triple-Negative Breast Cancer, Effective in Some
The investigational immunotherapy MPDL3280A was safe, tolerable, and showed early signs of durable clinical activity in patients with metastatic triple-negative breast cancer, according to data from a first-in-human phase I clinical trial presented at the AACR Annual Meeting 2015, held April 18 to 22 in Philadelphia (Abstract 2859).
“The emergence of approaches for harnessing the immune system to fight cancer is creating a lot of excitement for oncologists and immunologists, because many of the responses that are being achieved are prolonged,” said Leisha A. Emens, MD, PhD, Johns Hopkins Associate Professor of Oncology and Member of the Cancer Immunology and the Breast and Ovarian Cancer Programs at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center.
Study Findings
“The latest analysis of our data revealed a 24-week progression-free survival rate of 27%, with an objective response rate of 19%, and three of four responses are ongoing,” continued Dr. Emens. “This is very exciting, because longer responses are not typical of what occurs when patients with metastatic triple-negative breast cancer are treated with chemotherapy, which is the standard of care for this population. However, we need to validate these findings in larger cohorts of patients.”
Dr. Emens explained that the immunotherapy MPDL3280A is a monoclonal antibody, blocking the interaction between the PD-1 protein and its ligand PD-L1, which are found on T cells. She said that normally this interaction shuts off the ability of T cells to attack cancers and that blocking the interaction with MPDL3280A allows the T cells to once again eliminate tumor cells.
The phase I clinical trial is evaluating MPDL3280A as a potential treatment for a variety of advanced solid tumors. Dr. Emens and colleagues enrolled 54 patients with metastatic triple-negative breast cancer in the study, 69% having PD-L1 on 5% or more of immune cells infiltrating samples of their tumors and considered to have PD-L1–positive disease. Twenty-one of these PD-L1-positive patients could be assessed for signs of clinical activity.
Of the 54 patients (both PD-L1–negative and PD-L1–positive) who could be assessed for side effects, 63% experienced at least one drug-related adverse event, with 11% experiencing at least one grade 3 event. One patient experienced a grade 4 event. The most common drug-related adverse events were fatigue, fever, nausea, and loss of appetite.
This study was funded by Genentech.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
