Effect of Antacids on the Survival of Patients With Metastatic Urothelial Carcinoma Treated With Pembrolizumab.

INTRODUCTION: Concomitant medications can affect the efficacy of immune checkpoint inhibitors. The association between histamine-2 receptor antagonists (H2RAs), major antacids similar to proton pump inhibitors (PPIs), and the efficacy of pembrolizumab for metastatic urothelial carcinoma (mUC) treatment has been poorly evaluated. We evaluated the impact of PPIs and H2RAs on oncological outcomes in mUC patients treated with pembrolizumab. PATIENTS AND METHODS: This retrospective multicenter study included patients with mUC treated with pembrolizumab. Patients prescribed PPIs or H2RAs within 30 days before and after the initial administration were extracted. The overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), and objective response rates (ORR) were assessed. Kaplan-Meier survival curve analysis and multivariable Cox proportional hazard models were employed to assess the association between PPIs or H2RAs and survival outcomes. RESULTS: Overall, 404 patients were eligible for this study; 121 patients (29.9%) used PPIs, and 34 (8.4%) used H2RAs. Kaplan-Meier analysis showed significantly worse OS, CSS, and PFS in patients using PPIs compared to no PPIs (P = .010, .018, and .012, respectively). In multivariable analyses, the use of PPIs was a significant prognostic factor for worse OS (HR = 1.42, 95% CI 1.08-1.87, P = .011), CSS (HR = 1.45, 95% CI 1.09-1.93, P = .011), and PFS (HR = 1.35, 95% CI 1.05-1.73, P = .020). PPIs were not associated with ORRs. The use of H2RAs was not associated with survival or ORRs. CONCLUSION: PPIs were significantly associated with worse survival of patients with mUC treated with pembrolizumab, and H2RAs could be an alternative during administration. Both the oncological and gastrointestinal implications should be carefully considered when switching these antacids.

Prognostic impact of radiological tumor burden in patients with metastatic urothelial carcinoma treated with pembrolizumab.

PURPOSE: Radiological tumor burden has been reported to be prognostic in many malignancies in the immunotherapy era, yet whether it is prognostic in patients with metastatic urothelial carcinoma (mUC) treated with pembrolizumab remains uninvestigated. We sought to assess the predictive and prognostic value of radiological tumor burden in patients with mUC. METHODS: We performed a retrospective analysis of 308 patients with mUC treated with pembrolizumab. Radiological tumor burden was represented by baseline tumor size (BTS) and baseline tumor number (BTN). Optimal cut-off value of BTS was determined as 50 mm using the Youden index (small BTS: n = 194, large BTS: n = 114). Overall (OS), cancer-specific (CSS), progression-free survival (PFS), and objective response rate (ORR) were compared. Non-linear associations between BTS and OS and CSS were evaluated using restricted cubic splines. RESULTS: Patients with large BTS were less likely to have undergone the surgical resection of the primary tumor (P = 0.01), and more likely to have liver metastasis (P < 0.001) and more metastatic lesions (P < 0.001). On multivariable analyses controlling for the effects of confounders (resection of primary tumor, metastatic site, number of metastases and lactate dehydrogenase level), large BTS and high BTN were independently associated with worse OS (HR 1.52; P = 0.015, and HR 1.69; P = 0.018, respectively) and CSS (HR 1.59; P = 0.01, and HR 1.66; P = 0.031, respectively), but not PFS. Restricted cubic splines revealed BTS was correlated with OS and CSS in linear relationships. Additionally, large BTS was significantly predictive of lower ORR and complete response rate on univariable analyses (P = 0.041 and P = 0.032, respectively), but its association disappeared on multivariable analyses. CONCLUSION: Radiological tumor burden has independent prognostic value with a linear relationship in pembrolizumab-treated patients with mUC and might help drive the earlier introduction of second-line pembrolizumab and/or switching to subsequent therapies.