245 Background: Stereotactic body radiation therapy (SBRT) is an effective treatment for patients with hepatocellular carcinoma or liver metastases. Predictive biomarkers for liver toxicity would allow for careful patient selection and the adaptation of therapy. Prior studies have shown specific miRNAs are elevated prior to clinical signs of toxin induced liver injury. We hypothesized that miRNAs can be used to predict radiation induced liver toxicity prior to clinical manifestations. Methods: As part of an IRB approved clinical trial (NCT01522937) patients with liver tumors underwent a split course of SBRT. All patients underwent liver function testing using indocyanine green clearance (ICG) followed by three SBRT fractions. One month later ICG was reassessed and two more fractions were given if the patient did not have a decline in liver function. Plasma samples were obtained at baseline and 1 month after finishing three of five SBRT fractions for 89 patients. For this exploratory analysis, we selected the 10 patients that had a 2+ point increase in Child-Turcotte-Pugh score within 6 months of completing therapy and 19 additional patients without toxicity. The levels of 752 miRNAs were quantified for each sample using qPCR. We then used a univariate tree based classifier and the elastic net with 10-fold cross validation to calculate the AUC for predicting liver toxicity in individual and small groups of miRNAs, respectively. Results: Several miRNAs were found to be potentially predictive of toxicity on univariate tree based classifier analysis including the liver specific microRNA miR.122.3p, the epithelial specific miR.141.3p and miR.200b.3p, the neuroendocrine related miR.375 and miR.217, and miR.125a.5p which plays a role in hepatitis and regulates ERBB2 and ERBB3 signaling. The elastic net model achieved a conservative AUC estimate of 0.74 +/- 0.04 using 69 baseline miRNAs and 0.76 +/- 0.06 using 11 mid-treatment miRNAs to predict toxicity. Conclusions: Our preliminary analysis of the miRNAome from 29 patients receiving liver SBRT shows promising results for the ability of these markers to select patients at risk for radiation induced liver toxicity. Further validation in a larger patient cohort is needed. Clinical trial information: NCT01522937.
Scoring system predictive of survival for patients undergoing stereotactic body radiation therapy for liver tumors
