Small cell carcinoma of the bladder: the characteristics of molecular alterations, treatment, and follow-up

Treatment and survival of non-metastatic small cell carcinoma of the bladder from multiple centers in China

Small cell carcinoma of the bladder (SCCB) is a rare, highly malignant neuroendocrine tumor. This study attempted to analyze tumor characteristics, treatments and clinical outcomes in China. We conducted a retrospective analysis of patients diagnosed with non-metastatic SCCB at multi-institutions between January 2007 and January 2022. The Kaplan-Meier method was used to calculate survival. A total of 20 patients were included. 10 had localized disease (T1-2N0), and 10 had locally advanced disease (≥ T3 or N+). 13 received local treatment (partial cystectomy or transurethral resection of the bladder tumor) and 7 received radical treatment (radical cystectomy or radiotherapy). A total of 18 patients (90%) received chemotherapy (CT), either neoadjuvant CT (n = 5) or adjuvant CT (n = 13). The median OS for the receiving local treatment was 65.3 months (95% CI 0 to 138 months) and the corresponding 1-year, 2-year, and 3-year OS was 77%, 54%, and 54%, respectively. The median OS for the receiving radical treatment was not reached and the corresponding 1-year, 2-year, and 3-year OS was 100%, 100%, and 75%, respectively. The median PFS for receiving local treatment was 13.8 months (95% CI 9.3 to 18.3 months) and the corresponding 1-year, 2-year, and 3-year PFS was 46%, 31%, and 31%, respectively. The median PFS for the receiving radical treatment was not reached and the corresponding 1-year, 2-year, and 3-year PFS was 83%, 56%, and 56%, respectively. This study reported the largest cohort of non-metastatic SCCB among Chinese population. Given its metastatic potential, CT remained an essential part of the treatment. The survival outcomes of radical cystectomy and RT in non-metastatic SCCB were encouraging.

Small cell neuroendocrine carcinoma and poorly differentiated rhabdomyosarcomas of the urinary bladder in adults-A comparative analysis in favor of a common histogenesis

Rhabdomyosarcoma (RMS) of the urinary bladder in adults and elderly is an exceptionally rare neoplasm that displays poorly differentiated solid (alveolar-like) small cell pattern, frequently indistinguishable from small cell neuroendocrine carcinoma (SCNEC). However, the histogenesis of RMS and SCNEC and their inter-relationship have not been well studied and remained controversial. We herein analyzed 23 SCNEC and 3 small round cell RMS of the bladder for neuroendocrine (synaptophysin + chromogranin A) and myogenic (desmin + myogenin) marker expression and for TERT promoter mutations. In addition, the RMS cohort and one SCNEC that was revised to RMS were tested for gene fusions using targeted RNA sequencing (TruSight Illumina Panel which includes FOXO1 and most of RMS-related other genes). Overall, significant expression of myogenin and desmin was observed in one of 23 original SCNEC justifying a revised diagnosis to RMS. On the other hand, diffuse expression of synaptophysin was noted in 2 of the 4 RMS, but chromogranin A was not expressed in 3 RMS tested. TERT promoter mutations were detected in 15 of 22 (68%) SCNEC and in two of three (67%) assessable RMS cases, respectively. None of the four RMS cases had gene fusions. Our data highlights phenotypic and genetic overlap between SCNEC and RMS of the urinary bladder. High frequency of TERT promoter mutations in SCNEC is in line with their presumable urothelial origin. In addition, the presence of TERT promoter mutation in 2 of 3 RMS and lack of FOXO1 and other gene fusions in all 4 RMSs suggest a mucosal (urothelial) origin, probably representing extensive monomorphic rhabdomyoblastic transdifferentiation in SCNEC.

Durable Objective Response to Lurbinectedin in Small Cell Bladder Cancer with TP53 Mutation: A Molecular-Directed Strategy

Small cell bladder cancer (SCBC) is a rare and aggressive disease, often treated with platinum/etoposide-based chemotherapy. Key molecular drivers include the inactivation of onco-suppressor genes (TP53, RB1) and amplifications in proto-oncogenes (MYC). We report a patient with SCBC who achieved an objective and prolonged response to lurbinectedin, which has been approved for metastatic small cell lung cancer, after developing disease progression on cisplatin/etoposide and nivolumab/ipilimumab. A genomic analysis of a metastatic biopsy prior to lurbinectedin initiation revealed a TP53 mutation and amplification of the cell cycle regulators E2F3 and MYCL. A repeat biopsy following the development of lurbinectedin resistance showed a new actionable ERBB2 alteration without significant change in the tumor mutation burden (six mutations/Mb). The present report suggests that lurbinectedin may be active and should be further explored in SCBC harboring TP53 mutations and amplifications in E2F3 and MYC family complexes.

Clinical Outcomes of Small Cell Carcinoma of the Genitourinary Tract and the Prognostic Significance of the Tumor Immune Microenvironment

PURPOSE

Small cell carcinoma of the genitourinary tract (GU SCC) is a rare disease with a poor prognosis. There are only limited treatment options due to insufficient understanding of the disease. In this study, we analyzed the clinical outcomes of patients with GU SCC and their association with the tumor immune phenotype.

MATERIALS AND METHODS

Patients diagnosed with GU SCC were included. Survival outcomes according to the primary location (prostate and non-prostate) and stages (limited disease [LD] and extensive disease [ED]) were analyzed. We performed multiplex immunohistochemistry (IHC) in non-prostate SCC patients and analyzed the immune cell population.

RESULTS

A total of 77 patients were included in this study. Their median age was 71 years, 67 patients (87.0%) were male, and 48 patients (62.3%) had non-prostate SCC. All patients with ED (n=31, 40.3%) received etoposide plus platinum (EP) as initial treatment and median overall survival (OS) was 9.7 months (95% confidence interval [CI], 7.1 to 18.6). Patients with LD (n=46, 59.7%) received EP followed by radiotherapy or surgery, and 24-months OS rate was 63.6% (95% CI, 49.9 to 81.0). The multiplex IHC analysis of 21 patients with non-prostate SCC showed that patients with a higher density of programmed death-ligand 1-expressing CD68+CD206+ M2-like macrophages had significantly worse OS outcomes with an adjusted hazards ratio of 4.17 (95% CI, 1.25 to 14.29; adjusted p=0.02).

CONCLUSION

Patients with GU SCC had a poor prognosis, even those with localized disease. The tumor immune phenotypes were significantly associated with survival. This finding provides new insights for treating GU SCC.

Classification of bladder cancer cell lines according to regulon activity

Bladder cancer is one of the most frequent cancers and causes more than 150.000 deaths each year. During the last decade, several studies provided important aspects about genomic characterization, consensus subgroup definition, and transcriptional regulation of bladder cancer. Still, much more research needs to be done to characterize molecular signatures of this cancer in depth. At this point, the use of bladder cancer cell lines is quite useful for the identification and test of new signatures. In this study, we classified the bladder cancer cell lines according to the activities of regulons implicated in the regulation of primary bladder tumors. Our regulon gene expression-based classification revealed three groups, neuronal-basal (NB), luminal-papillary (LP), and basal-squamous (BS). These regulon gene expression-based classifications showed a quite good concordance with the consensus subgroups assigned by the primary bladder cancer classifier. Importantly, we identified FGFR1 regulon to be involved in the characterization of the NB group, where neuroendocrine signature genes were significantly upregulated, and further β-catenin was shown to have significantly higher nuclear localization. LP groups were mainly driven by the regulons ERBB2, FOXA1, GATA3, and PPARG, and they showed upregulation of the genes involved in epithelial differentiation and urogenital development, while the activity of EGFR, FOXM1, STAT3, and HIF1A was implicated for the regulation of BS group. Collectively, our results and classifications may serve as an important guide for the selection and use of bladder cancer cell lines for experimental strategies, which aim to manipulate regulons critical for bladder cancer development.

Primary Small Cell Carcinoma of the Bladder

A 64-year-old Caucasian man with a 20 to 25-pack-year cigarette smoking history presented to his primary care provider with the chief complaint of gross hematuria after experiencing three to four months of urinary frequency and urgency. His workup consisted of laboratory blood work, a renal/bladder ultrasound (US), a CT scan without contrast, cystoscopy with biopsy (with an attempted transurethral resection of bladder tumor), and a PET scan. He was diagnosed with stage T4 small cell carcinoma of the bladder (SCCB) shortly after seeking medical care with metastases to the liver, bone, and lymph nodes. There was no evidence of lung involvement. The patient's primary concerns included difficulty urinating and sustained hematuria. He underwent palliative radiotherapy and placement of bilateral nephrostomy tubes in order to preserve his quality of life. He also received a chemotherapy regimen consisting of cisplatin, etoposide, and atezolizumab. The patient underwent hospice care and died approximately six months after the presentation.

Small cell carcinoma of the bladder with coexisting prostate adenocarcinoma: two cases report and literature review

BACKGROUND

Primary small cell carcinoma of the bladder (SCCB) is a rare disease of the genitourinary tract and reported limitedly. SCCB is very aggressive and always mixed with other histologic components, but coexistence of SCCB and prostate adenocarcinoma is extremely rare.

CASES PRESENTATION

Two aged males (72 and 58 years) were included in this study. Both of them presented with gross hematuria as initial symptom. Magnetic resonance imaging (MRI) demonstrated protruding lesions in the urinary bladder. Pathological examination after radical cystectomy and prostatectomy showed the concurrence of SCCB and prostate adenocarcinoma. One patient died of liver and lung metastasis 8 months after surgery, and the other patient was still alive after 19 months of follow-up.

CONCLUSION

In this paper, we reported two unusual cases of coexistence of SCCB and prostate adenocarcinoma, and reviewed relative literatures with respect to the epidemiology, clinical features, pathologic features, diagnosis, treatment and prognosis of SCCB.