Treatments Outcomes in Histological Variants and Non-Urothelial Bladder Cancer: Results of a Multicenter Retrospective Study.

Less than one-third of bladder cancers are non-pure urothelial carcinoma [with variant histological (VH) or non-urothelial carcinoma (non-UC)] for which no treatment guidelines are available. We aim to evaluate the efficacy of systemic treatments in VH or non-UC bladder cancers.

Multicenter retrospective analysis of patients treated for advanced or metastatic VH or non-UC bladder cancers. Primary endpoint was overall response rate (ORR) according to treatment line, regimen and histology subtype. Secondary endpoints were progression-free survival (PFS) and overall survival (OS).

Between 2005 and 2020, 46 patients from seven centers were included. The median age was 66 years (58.75; 74.75), 65.2% were male and 67.2% presented VH. At first line, the ORR for the entire population was 54.4% and median OS was 21.6 months (95% confidence interval [CI]: 14.2-38.6). The ORR of the 37 patients treated with chemotherapy at first line was 62.2% with median PFS and OS of 7.3 (95% CI: 4.5-8.6) and 21.6 months (95% CI: 14.2-35.7), respectively. Dose dense MVAC and platinum doublet chemotherapy had the highest ORR (71.4% and 65.2%). The 9 patients treated with immunotherapy at first line had an ORR of 22.2%, a median PFS of 3.3 months (95% CI:2.3-NR) and the median OS was not reached (95% CI:13.8-NR). Response to treatment varied depending on the histological sub-types and on the treatment type.

Chemotherapy and immunotherapy have shown to be effective in VH or non-UC cancers, a rare histological subtype for which we currently have very little data in the literature.

Frontiers in oncology. 2021 May 20*** epublish ***

Nicolas Epaillard, Pauline Parent, Yohann Loriot, Pernelle Lavaud, E-B Vera-Cea, Nieves Martinez-Chanza, Alejo Rodriguez-Vida, Clement Dumont, Rebeca Lozano, Casilda Llácer, Raffaele Ratta, Stephane Oudard, Constance Thibault, Edouard Auclin

Medical Oncology Department, Hôpital Européen Georges Pompidou, AP-HP, Université de Paris, Paris, France., Gustave Roussy, Université Paris-Sud, Université Paris-Saclay, Villejuif, France., Medical Oncology Department, Hospital del Mar, IMIM Research Institute, Barcelona, Spain., Medical Oncology Departments, Jules Bordet Institute, Université Libre de Bruxelles, Brussels, Belgium., Medical Oncology Department, Hôpital Saint Louis, AP-HP, Université de Paris, Paris, France., Prostate Cancer Clinical Research Unit, Spanish National Cancer Research Centre, Madrid, Spain., Genitourinary Oncology Translational Research Group, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain., Medical Oncology Department, Hopital Foch, Suresnes, France.