Prediction of pathologic response of colorectal liver metastases (CRLM) to transcatheter hepatic therapy with irinotecan-eluting beads by hepatic activation of irinotecan

438 Background: For patients with CRLM, good pathologic response to neoadjuvant chemotherapy is associated with improved overall survival. However, systemic therapy can increase postoperative morbidity and mortality. DEBIRI gives sustained delivery of drug directly to tumor, maximising response and reducing systemic exposure. Predictive markers of response would allow selection of patients most likely to benefit. This study assessed drug metabolism within normal hepatic parenchyma as a predictor of pathologic response of CRLM to DEBIRI. Methods: Patients with resectable CRLM received single targeted DEBIRI (up to 200mg) 1 month pre-hepatectomy. Hepatic parenchyma was harvested at resection. Parenchymal drug metabolism and protein expression were characterised with a novel LC-MS/MS assay and western blot, and correlated with pathologic tumour response. Results: Ten patients assessed. Median residual tumour 30% (range 10-50%), necrosis 40% (range 40-60%) and fibrosis 20% (range 10-40%). Microsomal formation...