We will develop and validate a new assay system to replace existing immunocytochemical assays for detecting occult micrometastases in bone marrow of patients with primary breast cancer. This assay would offer simplicity, low cost, and a quantitative end point. The assay is based on an innovative amplification mechanism, the bacterial chain reaction (BCR), which is potentially capable of lowering the detection limit to one micrometastasis in 10 million bone marrow cells. The BCR utilizes living cells of an autosyntrophic strain of Escherichia coil to amplify signals from reporter molecules, e.g., enzyme labeled monoclonal antibodies.Under the BCR conditions, reporter molecules trigger nearby autosyntrophic cells to initiate a proliferative chain reaction resulting in discrete visible bacterial colonies clustered around tumor cells. Phase I will optimize the BCR assay and assess its detection limits of using a model system. For Phase II, the BCR assay will be validated by applying it to detection and enumeration of occult micrometastases in bone marrow specimens from patients with primary breast cancer. The final objective is to produce a BCR assay kit to be marketed as a diagnostic tool in the clinic.Commercial ApplicationsThe major commercial application of the BCR assay would be to identify at the time of initial surgery individual breast cancer patients who are at high risk of relapsing within a 5 year period. The assay has the potential to become a prescribed preclinical procedure if, as current clinical studies indicate, occult micrometastases in the patients' bone marrow are reliable predictors of subsequent relapse.National Cancer Institute (NCI)
