Major Durable Response of Pembrolizumab in Chemotherapy Refractory Small Cell Bladder Cancer: A Case Report

Abstract

Small cell carcinoma of the urinary bladder is a rare subtype (incidence of 1–9/1,000,000), characterized by an aggressive behavior with early metastasis and poor prognosis. Chemotherapy, radiation, and surgery are the usual treatment options, but to date, no accepted standard treatment exists. Since small cell bladder cancer shares similar clinicopathological features with small cell lung cancer, the same type of chemotherapy has been used. Recently, immune checkpoint inhibitors have shown effect in small cell lung cancer, but data regarding small cell bladder cancer is insufficient. Here we present a case where a 73-year-old male with chemorefractory metastatic small cell bladder cancer received a successful treatment with immune checkpoint inhibitor pembrolizumab resulting in a major durable response and no side effects. To our knowledge, this is the second case report on successful treatment of the rare subtype of small cell bladder cancer with an immune checkpoint inhibitor, supporting the use of pembrolizumab as a therapeutic option for small cell bladder cancer. Serum neuron-specific enolase was a useful biomarker both for chemo- and immunotherapy response.

Effect of chemotherapy alone or combined with immunotherapy for locally advanced or metastatic genitourinary small cell carcinoma: a real-world retrospective study

“…A phase II study of nivolumab and ipilimumab for patients with advanced rare genitourinary malignancies demonstrated responses in 7 out of 19 patients, with responses observed in 2 of 3 patients with GSCC (one with CR) [ 17 ]. Several case reports were published also showing good responses to ICIs in patients with SCCB [ 18 – 20 ]. In accordance with the results mentioned above, our study also found that GSCC was associated with superior survival outcomes when adding immunotherapy to chemotherapy.…”

A Rare but Real Entity: Bladder Neuroendocrine Cancer

“…PD-1 (programmed cell death protein 1) and PD-L1 (programmed death-ligand 1) inhibitors have also been tested in this disorder, and although they have generally not been successful, positive results have been described in case reports. Clinical trials with adequate evidence are ongoing [11,[30][31][32].…”

A Case of Bladder Large Cell Carcinoma with Review of the Literature

“…Based on these observations, a role of checkpoint inhibitors for NEC of the bladder was hypothesized. Although direct experience with bladder LCNEC is nearly absent so far, results obtained in few patients with SCNEC of the urinary system are promising and could lead to new treatment option for patients affected by this rare malignancy [67][68][69]. Moreover, investigating targetable genomic alterations in these patients may help improve their multimodal treatment [6,[70][71][72].…”