Fig. 4.

SHR6390 combined with PTX or CDDP offered synergistic inhibitory effects in ESCC xenografts. a–d Antitumor effects of SHR6390 and PTX or CDDP alone or in combination in Eca 9706 and Eca 109 xenografts. The growth of tumors treated with SHR6390 combined with PTX or CDDP was significantly suppressed in the Eca 9706 xenografts. e, f Effects of combination therapy on the Cyclin D1-CDK4/6-Rb pathway in vivo. Tumor specimen of Eca 109 and Eca 9706 xenografts were harvested after the end of treatment followed by analysis of lysates for Rb, pRb, CDK4, CDK6, Cyclin D1. The levels of Rb, pRb, CDK4, Cyclin D1 and CDK6 were quantified by using the software Image Pro. Tumor growth inhibition (TGI) values were calculated using the following formula: TGI = ΔT/ΔC × 100% (ΔT = tumor volume change of the drug-treated group, ΔC = tumor volume change of the control group on the final day of the study). Tumor regression rate (TRR) = (pre-drug tumor volume-post-drug tumor volume) × 100%/pre-drug tumor volume. Tumor volumes are expressed as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 by one-way ANOVA or unpaired two-tailed t test