Feasibility of testing core needle biopsies ex vivo in the ChemoFx assay

20073 Background: Multiple chemotherapy options exist for the treatment of primary breast cancer. While response rates are good, many patients are treated with unnecessary or ineffective chemotherapy. Inadequate treatments are partly due to the lack of accurate predictors of response in individual patients. To predict an individual’s response to therapy, ex vivo chemosensitivity and resistance assays (CSRAs) have long been evaluated, but have been limited by technical difficulties, including the need for large (1–2 gm) amounts of fresh tissue. However, these problems have largely been overcome with new technology. Novel methods used in Precision Therapeutics’ ChemoFx assay allow for testing smaller amounts of tissue (35 mg). The reduced tissue requirement is crucial in the breast cancer setting, as the diagnosis is often made by percutaneous biopsy. The goals of the study were to determine the growth success rate of culturing epithelial cells from breast tissue core needle biopsies and the feasibility of testing the cells in the assay. Methods: A prospective feasibility study involving women with invasive primary breast cancer. One to four core needle biopsy specimens were collected using a 14 gauge needle (est. per patient yield <50 mg) and submitted to Precision Therapeutics. A primary culture of each specimen was established and the ex vivo chemoresponse profiles of each culture were evaluated. Drugs tested included capecitabine, cisplatin, cyclophosphamide, docetaxel, doxorubicin, epirubicin, etoposide, 5-fluorouracil, gemcitabine, irinotecan, paclitaxel, and vinorelbine. Results: 21 of 25 (84%, 95% CI: 68% to 97%) specimens grew successfully; all 21 were tested for chemoresponsiveness with the assay. Of the 4 subjects with unsuccessful ex vivo cultures, 2 had no growth, 1 failed plating for culture, and 1 failed IHC testing due to overgrowth of non-epithelial cells. The average number of drugs tested for each specimen was 7 (range: 1–15). Conclusions: This study demonstrates that core needle biopsies from primary breast tumors can be successfully cultured and tested for chemoresponsiveness using the ChemoFx assay. The ability to perform ex vivo chemoresponse testing on core needle biopsies greatly increases the utility of the assay in adjuvant or neoadjuvant primary breast cancer settings. [Table: see text]