Association of response to first-line chemotherapy with the efficacy of atezolizumab in patients with metastatic urothelial carcinoma.
Authors: Deniz Tural, Omer Fatih Olmez, Ahmet Taner Sümbül, Mehmet Artac, Nail Ozhan, Emre Akar, Burcu Cakar, Osman Kostek, Meltem Ekenel, Hasan Senol Coskun, Fatih Selcukbiricik, Özge Keskin, Fatma Paksoy Turkoz, kerem oruc, Selami Bayram, Ugur Yilmaz, Irem Bilgetekin, Birol Yildiz, Mehmet Ali Nahit Sendur, Mustafa Erman
Journal: Journal of Clinical Oncology (2021)

409 Background: In the current study, we evaluated whether the response first-line chemotherapy could impact atezolizumab benefit in terms of response rate and overall survival in patients with metastatic urothelial carcinoma. Methods: In this study, we present the retrospective analysis of 105 patients with urothelial cancer treated with ATZ after progression on first-line chemotherapy. The association between response to first-line chemotherapy and ATZ was assessed using Fisher’s exact test. Overall survival (OS) was estimated by using the Kaplan-Meier method. Univariate analysis was used to identify clinical and laboratory factors that significantly impact OS. Variables were retained for multivariate analysis if they had a statistical relationship with OS (p˂0.1) and then included the final model if p˂0.05. Results: Best response to first-line chemotherapy was complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD) in 5(4.8%), 38(36.2%), 16(15.2%), 46(43.8%) patients, respectively. Best response to atezolizumab was CR, PR, SD, PD in 9(8.6%), 22(21%), 23(21,9%), 51(48,5%). Forty (74.1%) of patients who benefited from first-line chemotherapy also benefited from atezolizumab, while only 14 (25.9%) of patients with initial PD after first-line chemotherapy subsequently experienced clinical benefit with atezolizumab (Fisher’s exact test, p=0.001). Patients with clinical benefit from first-line chemotherapy had a higher OS. The median OS of atezolizumab were 14.8 and 3.4 months for patients with clinical benefit and progressive disease in response to first-line chemotherapy, respectively (log-rank p=0.001). In univariate analysis, Patients with clinical benefit from first-line chemotherapy, liver metastases, baseline creatinine clearance less (GFR)than 60 ml/min, Eastern Cooperative Oncology Group (ECOG) performance status (1 ≥), and hemoglobin levels below 10 mg/dl were all significantly associated with OS. Three of the adverse prognostic factors according to the Bellmunt criteria were independent factor of short survival: liver metastases (Hazard Ratio [HR]= 0.6; 95% CI 0.174-0.60; p=0.04), ECOG PS≥1 (HR= 0.36; 95% CI 0.2-0.66; p=0.001), and Hemoglobin level below 10 mg/dl (HR= 0.36; 95% CI 0.2-0.66; p &lt;0.001). In addition, Patients with clinical benefit from first-line chemotherapy (HR= 0.39; 95% CI 0.24-0.65; p &lt;0.001) maintained a significant association with OS in multivariate analysis. Conclusions: Our study demonstrated that clinical benefit from first-line chemotherapy was independent prognostic factor on OS in patients' use of atezolizumab as second-line treatment in metastatic bladder cancer. Furthermore, these findings are important for stratification factors for future immunotherapy study design in patients with bladder cancer who have progressed after first-line chemotherapy.