Use of a tumor-cell enrichment column for the enhanced detection of minimal residual disease in the BM or apheresis peripheral blood transplant products of breast-cancer patients

Background: Contaminating tumor cells present in the BM or apheresis peripheral blood (APB) autologous transplant products have been shown to contribute to relapse following high-dose chemotherapy and stem-cell rescue (HDC/ASCR). Enhanced methods for tumor detection in BM or APB products for breast-cancer patients are required. Methods: We evaluated a laboratory-scale tumor-cell enrichment column (TEC) as an enhanced method of detecting tumor cells in APB or BM of breast-cancer patients. Seventeen women with breast cancer (14 Stage IV and three Stage III) were evaluated using the TEC for residual tumor cells present in 20 samples of APB or BM biopsies following HDC/ASCR. Results: Using conventional histological staining methods (without TEC), only one patient had evidence of tumor cells present in the BM biopsy, while 16 patients had negative biopsies. Using the TEC for tumor cell capture and immunocytochemical (ICC) staining with anti-cytokeratin MAb (CAM 5.2) for tumor detection, we were able to positively identify tumor cells in 20 samples (14 BM aspirates and six APB products). In 15 samples (nine BM and six APB), we used CAM 5.2 to positively identify cytokeratin⁺ cells prior to using the TEC. However, positive cells were detected only after using the TEC in the remaining five samples. The level of sensitivity was significantly enhanced (p ≤ 0.05) by 100-400 fold in the post-TEC (absorbed) fraction compared with the pre-TEC (post-Ficoll) fraction. Discussion: We conclude from this study that the use of TEC improves our ability to detect residual breast-cancer cells in the APB or BM and could be potentially utilized to purge contaminating tumor cells from the stem-cell transplant.