Biocept, Inc. announces a collaboration agreement to participate in an investigator-initiated, non-therapeutic pilot study to evaluate the cerebrospinal fluid tumor and immune cell microenvironment in patients with metastatic breast cancer and brain metastases and/or leptomeningeal disease. The study is designed to identify biomarkers associated with central nervous system (CNS) metastasis, enabling a better understanding of treatment response, prognosis, and treatment resistance that may improve the management of CNS disease in patients with metastatic breast cancer. The study is being conducted by breast oncologists Michelle E. Melisko, M.D. and Laura A. Huppert, M.D. at the University of California, San Francisco (UCSF) under a grant from the California Breast Cancer Research Program and the UCSF Brain Spore.

Results from cerebrospinal fluid using Biocept's CNSide assay and matched patient blood samples will be analyzed and compared to detect and characterize cancer in the cerebrospinal fluid with the goal of identifying new targets and to guide therapeutic decisions. In addition, Drs. Huppert and Melisko will work with Dr. Chris Im in the laboratory of Dr. Max Krummel at UCSF to examine the immune-cell microenvironment in a companion study, and the results will be analyzed together.

The pilot study will collect cerebrospinal fluid and blood samples from 20 patients with metastatic breast cancer and brain metastases and/or leptomeningeal disease. The samples will be analyzed for the presence, quantity and mutational profile of cerebrospinal fluid ctDNA and cerebrospinal fluid tumor cells, which will be paired with results from peripheral blood mononuclear cell samples. Exploratory analysis of changes in cerebrospinal fluid DNA, tumor cell, and immune cell characteristics will be performed over time in a limited number of serial samples.

The cerebrospinal fluid findings will then be correlated with clinical outcomes, including CNS disease progression and survival. One of the most devastating complications of metastatic breast cancer is the development of CNS disease, including brain metastases and/or leptomeningeal disease. Among patients with metastatic breast cancer, approximately 15-45% develop brain metastases and approximately 5-10% develop leptomeningeal disease during the course of their disease, resulting in significant morbidity and mortality.

As patient outcomes improve with better systemic treatment options, control of CNS disease has become increasingly important to reduce morbidity and prolong survival. Patients with leptomeningeal disease are often excluded from clinical trials and there are few effective treatments. In order to develop better tools for the diagnosis and treatment of metastatic breast cancer with CNS disease, it is critical to better understand the biology of this condition.

Specifically, the profiling of the cerebrospinal fluid tumor and immune microenvironment in patients with brain metastases and/or leptomeningeal disease will enable a better understanding of the characteristics that may contribute to the development and progression of CNS disease.