Abstract
Although elevated serum levels of soluble CD40 ligand (sCD40L) were reported in patients with cancer, the importance of high sCD40L levels in clinical oncology remains unknown. We conducted a post hoc analysis of the AMATERASU randomized clinical trial of vitamin D3 supplementation (2000 IU/day) in patients with digestive tract cancer to assess its significance. Serum sCD40L levels were measured by ELISA in 294 residual samples, and were divided into tertiles. In patients with colorectal cancer (CRC), 5-year relapse-free survival (RFS) rates in the middle and highest tertiles were 61.6% and 61.2%, respectively, which was significantly lower than 83.8% in the lowest tertile. A Cox proportional hazard analysis showed that the lowest tertile had a significantly lower risk of relapse or death than the highest tertile even with multivariate adjustment (hazard ratio (HR), 0.30; 95% confidence interval (CI), 0.11-0.80; p = 0.016). In the subgroup of CRC patients with the highest tertile of sCD40L, the 5-year RFS rate in the vitamin D group was 77.9%, which was significantly higher than 33.2% in the placebo group (HR, 0.30; 95% CI, 0.11-0.81; p = 0.018 [Pinteraction = 0.04]). In conclusion, elevated sCD40L might be a biomarker of poor prognosis in patients with CRC, but vitamin D supplementation might improve RFS in patients with high sCD40L.