Development and applicability of integrative tumor response assays for metastatic colorectal cancer

Aim: The present study investigated how well the results of integrative tumor-response assay (ITRA) compared to those of clinical response to chemotherapy in patients with metastatic colorectal cancer (CRC). Patients and Methods: A total of 129 patients with metastatic CRC were prospectively enrolled. ITRA consisted of two sequential histoculture drug-response assays (HDRAs). First-stage HDRAs were performed using 5-fluorouracil with leucovorin and oxaliplatin (FX), or with irinotecan (FR). Second-stage HDRAs (ITRA) were performed for cells surviving after the first-stage HDRA, using FX, FR, and their combinations with bevacizumab and cetuximab. Results: Among 129 patients, 42 (32.6%) completed second-line chemotherapy, results that correlated with those of ITRA. The accuracy of ITRA for predicting response to second-line chemotherapy was 61.9% (26/42), with a sensitivity of 44.4% (8/18) and a specificity of 75% (18/24). Conclusion: Despite its relatively low accuracy, ITRA might be a useful technique for predicting therapeutic efficacy and selecting for appropriate first-line and second-line anticancer regimens for patients.