Serum CCL27 predicts the response to Bacillus Calmette-Guerin immunotherapy in non-muscle-invasive bladder cancer

The prediction of the response to Bacillus Calmette-Guerin (BCG) can help identify non-muscle-invasive bladder cancer (NMIBC) patients that may be better served with alternative therapy. Several cytokine profiles present promising results, but they are difficult to use in clinical practice. In this prospective, longitudinal study, we tried to identify reliable serum cytokines/chemokines to predict the response to BCG using samples collected before and during BCG induction therapy. We used the Bio-plex multiplex assays to identify potential BCG failure-related serum cytokines/chemokines in the discovery set (n = 13). After screening, we identified CCL27 as the top candidate biomarker for predicting the response to BCG (P = .003). In the validation set, we found that the AUC of the baseline CCL27 was 0.730 (95% CI 0.515–0.945, P = .040) along with 67% sensitivity, 78% specificity. The changes from baseline to last timepoint can also distinguish BCG responders from non-responders (AUC: 0.726, 95% CI 0.474–0.979, P = .044). Moreover, the combination score of serum CCL27 (CS(CCL27)), based on the baseline and changes of CCL27, could further improve the predictive accuracy with an AUC of 0.897 (95% CI 0.790–1.000, P < .001). The correlations between CCL27 and local/systemic immunologic parameters were further analyzed. The level of serum CCL27 was strongly correlated with regulatory T cells (Tregs) in the tumor microenvironment (P = .002), indicating that CCL27 may promote the recruitment of Tregs into the tumor microenvironment. Our results show that serum CCL27 may represent a practical and reliable marker for the prediction of the response to BCG in NMIBC.