In our dataset, a threshold concentration of 370 pg/mL revealed the optimal combination of specificity (80%) and sensitivity (56%) in predicting SVR patients. We then determined our optimal IP-10 level to correctly predict both SVR as well as nonresponse. A threshold value of 550 pg/mL yielded the

highest rate of true positives or negatives (69%), and correlated well with the 600 pg/mL cutoff (68% true positives or negatives predicted in our dataset). Finally, logistic regression analysis PLX4032 in vivo of pretreatment IP-10 concentrations enabled fitting the probability of SVR for specific IP-10 levels measured in individual patients, and demonstrated a highly significant effect of IP-10 (P< 0.0001; Supporting Fig. 1, gray curve). When comparing pretreatment IP-10 serum levels of CA and AA patients, no significant differences were observed in separate analyses of responders (P = 0.75) and nonresponders (P = 0.97) (Table 1).

The significant (P = 0.015) difference in baseline serum IP-10 level between CA and AA patients that was observed in the overall Selleckchem Ponatinib study cohort can most likely be explained by the unbalanced composition of the cohort (IFN treatment response rate in the CA subgroup was 75% versus 40% in the AA subgroup). The highly significant difference in IP-10 serum level between responders and nonresponders to IFN therapy was found both in CA and AA patients (Table 1). Logistic regression analyses of baseline IP-10 levels were used to generate treatment response curves for CA and AA patients (Supporting Fig. 1). The response curves for AA and CA patients revealed a significant effect of both IP-10 (P< 0.0001) and race (P< 0.0001), but no significant interaction between IP-10 and race (P = 0.08). Of the 210 patients genotyped, 30% were CC, 49% were CT, and 21% were TT. A significant association between IL28B

MCE genotype and treatment response was observed: corresponding SVR rates were 87% for CC, 50% for CT, and 39% for TT (P< 0.0001) (Table 2). For CA patients, 49% were CC with an SVR of 91%, 41% were CT with an SVR of 67%, and 10% were TT with an SVR of 45% (P< 0.001). For AA patients, only 9% were CC with an SVR of 67%, 58% were CT with an SVR of 35%, and 33% were TT with an SVR of 36% (P = 0.20). Mean serum IP-10 levels were similar for all patients regardless of IL28B genotype both in CA patients (P = 0.27) and AA patients (P = 0.58) (Fig. 2). This lack of correlation between serum IP-10 and IL28B genotype indicates that the associations with SVR observed for both of these markers are independent. Using the 600 pg/mL cutoff for pretreatment IP-10 levels, the SVR rate for our cohort of patients with both serum IP-10 and IL28B genotype data available (n = 210) was 69% for those with a low IP-10 level (<600 pg/mL) and 35% for those with a high IP-10 level (>600 pg/mL) (P< 0.0001).