RESUMEN
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.
RESUMEN
BACKGROUND: Pemetrexed, a multi-folate inhibitor combined with a platinum compound is the first-line treatment of malignant mesothelioma, but median survival is still one year. Intrinsic and acquired resistance to pemetrexed is common, but its biological basis is obscure. Here we report for the first time a genome-wide profile of acquired resistance in the tumour from an exceptional case with advanced pleural mesothelioma and almost six years survival after 39 cycles of second-line pemetrexed/carboplatin treatment. METHODOLOGY AND PRINCIPAL FINDINGS: Genome-wide analysis with Illumina BeadChip Kit of 25,000 genes was performed on mRNA from pre-treatment and post-resistance biopsies from this individual as well on case and control samples from our previously published study (in total 17 samples). Cell specific expression of proteins encoded by selected genes were analysed by immunohistochemistry. Serial serum levels of CA125, CYFRA21-1 and SMRP levels were examined. TS protein, the main target of pemetrexed was overexpressed. Proteins and genes related to DNA damage response, elongation and telomere extension and repair related directly and indirectly to platinum resistance were overexpressed, as the CHK1 protein and the genes CHEK2, LIG3, POLD1, POLA2, FANCD2, PRPF19, RECQ5 respectively, the last two not previously described in mesothelioma. We observed a down-regulation of leukocyte transendothelial migration and cell adhesion molecules pathways. Silencing of NT5C in two mesothelioma cell lines did not sensitize the cells to Pemetrexed. Proposed resistance markers are TS, KRT7/ CK7, TYMP/ thymidine phosphorylase and down-regulated SPARCL1 and CDKN1B. Moreover, comparison of the primary expression of the sensitive versus a primary resistant case showed multi-fold overexpressed DNA repair, cell cycle, cytokinesis, and spindle formation in the latter. Serum CA125 and SMRP reflected the clinical and radiological course and tumour burden. CONCLUSIONS: Genome-wide microarray of mesothelioma pre- and post-resistance biopsies indicated a novel resistance signature to pemetrexed/carboplatin that deserve validation in a larger cohort.
