Clinicopathological characteristics, molecular landscape, and biomarker landscape for predicting the efficacy of PD-1/PD-L1 inhibitors in Chinese population with mismatch repair deficient urothelial carcinoma: a real-world study.

Urothelial carcinoma (UC) with deficient mismatch repair (dMMR) is a specific subtype of UC characterized by the loss of mismatch repair (MMR) proteins and its association with Lynch syndrome (LS). However, comprehensive real-world data on the incidence, clinicopathological characteristics, molecular landscape, and biomarker landscape for predicting the efficacy of PD-1/PD-L1 inhibitors in the Chinese patients with dMMR UC remains unknown. We analyzed 374 patients with bladder urothelial carcinoma (BUC) and 232 patients with upper tract urothelial carcinoma (UTUC) using tissue microarrays, immunohistochemistry, and targeted next-generation sequencing. Results showed the incidence of dMMR UC was higher in the upper urinary tract than in the bladder. Genomic analysis identified frequent mutations in KMT2D and KMT2C genes and LS was confirmed in 53.8% of dMMR UC cases. dMMR UC cases displayed microsatellite instability-high (MSI-H) (PCR method) in 91.7% and tumor mutational burden-high (TMB-H) in 40% of cases. The density of intratumoral CD8+ T cells correlated with better overall survival in dMMR UC patients. Positive PD-L1 expression was found in 20% cases, but some patients positively responded to immunotherapy despite negative PD-L1 expression. Our findings provide valuable insights into the characteristics of dMMR UC in the Chinese population and highlights the relevance of genetic testing and immunotherapy biomarkers for treatment decisions.

Ma YT ，Hua F ，Zhong XM ，Xue YJ ，Li J ，Nie YC ，Zhang XD ，Ma JW ，Lin CH ，Zhang HZ ，He W ，Sha D ，Zhao MQ ，Yao ZG ... -  《Frontiers in Immunology》

Case Report: Potential Predictive Value of MMR/MSI Status and PD-1 Expression in Immunotherapy for Urothelial Carcinoma.

Immune checkpoint inhibitors (ICIs) have shown encouraging outcomes against Lynch syndrome (LS)-associated colorectal cancer (CRC) and endometrial cancer with mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H). However, there is as yet no clarity on the safety and efficacy of immunotherapy combined with chemotherapy in LS-associated urothelial carcinoma (UC). Here, we report a patient with recurrent and metastatic LS-associated UC who achieved sustained response to programmed death protein 1 (PD-1) inhibitor combined with chemotherapy over 31 months, during which the side effects of immunotherapy could be controlled and managed. Our findings indicate that the dMMR/MSI status and PD-1 expression in UC may have potential predictive value for the response to PD-1-targeted immunotherapy. Our case supports the inclusion of such combination and/or monotherapy for UC in clinical studies and using dMMR/MSI status and PD-1 expression as potential predictive biomarkers for assessment of the therapeutic response.

Ma YT ，Yang HL ，Yan L ，Hua F ，Wang DG ，Xu GY ，Li Y ，Xue YJ ，Qin YJ ，Sha D ，Ning H ，Zhao MQ ，Yao ZG ... -  《-》

ESMO recommendations on microsatellite instability testing for immunotherapy in cancer, and its relationship with PD-1/PD-L1 expression and tumour mutational burden: a systematic review-based approach.

Cancers with a defective DNA mismatch repair (dMMR) system contain thousands of mutations most frequently located in monomorphic microsatellites and are thereby defined as having microsatellite instability (MSI). Therefore, MSI is a marker of dMMR. MSI/dMMR can be identified using immunohistochemistry to detect loss of MMR proteins and/or molecular tests to show microsatellite alterations. Together with tumour mutational burden (TMB) and PD-1/PD-L1 expression, it plays a role as a predictive biomarker for immunotherapy. To define best practices to implement the detection of dMMR tumours in clinical practice, the ESMO Translational Research and Precision Medicine Working Group launched a collaborative project, based on a systematic review-approach, to generate consensus recommendations on the: (i) definitions related to the concept of MSI/dMMR; (ii) methods of MSI/dMMR testing and (iii) relationships between MSI, TMB and PD-1/PD-L1 expression. The MSI-related definitions, for which a consensus frame-work was used to establish definitions, included: 'microsatellites', 'MSI', 'DNA mismatch repair' and 'features of MSI tumour'. This consensus also provides recommendations on MSI testing; immunohistochemistry for the mismatch repair proteins MLH1, MSH2, MSH6 and PMS2 represents the first action to assess MSI/dMMR (consensus with strong agreement); the second method of MSI/dMMR testing is represented by polymerase chain reaction (PCR)-based assessment of microsatellite alterations using five microsatellite markers including at least BAT-25 and BAT-26 (strong agreement). Next-generation sequencing, coupling MSI and TMB analysis, may represent a decisive tool for selecting patients for immunotherapy, for common or rare cancers not belonging to the spectrum of Lynch syndrome (very strong agreement). The relationships between MSI, TMB and PD-1/PD-L1 expression are complex, and differ according to tumour types. This ESMO initiative is a response to the urgent questions raised by the growing success of immunotherapy and provides also important insights on the relationships between MSI, TMB and PD-1/PD-L1.

Luchini C ，Bibeau F ，Ligtenberg MJL ，Singh N ，Nottegar A ，Bosse T ，Miller R ，Riaz N ，Douillard JY ，Andre F ，Scarpa A ... -  《-》

A Comprehensive Biomarker Analysis of Microsatellite Unstable/Mismatch Repair Deficient Colorectal Cancer Cohort Treated with Immunotherapy.

Élez E ，Mulet-Margalef N ，Sanso M ，Ruiz-Pace F ，Mancuso FM ，Comas R ，Ros J ，Argilés G ，Martini G ，Sanz-Garcia E ，Baraibar I ，Salvà F ，Noguerido A ，Cuadra-Urteaga JL ，Fasani R ，Garcia A ，Jimenez J ，Aguilar S ，Landolfi S ，Hernández-Losa J ，Braña I ，Nuciforo P ，Dienstmann R ，Tabernero J ，Salazar R ，Vivancos A ... -  《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》

Mismatch repair-deficient colorectal cancer: a model of immunogenic and immune cell-rich tumor despite nonsignificant programmed cell death ligand-1 expression in tumor cells.

Mismatch repair-deficient (dMMR) colorectal cancers (CRCs) are good responders to anti-programmed cell death ligand-1 (PD-L1) immunotherapy, but the value of PD-L1 testing remains unclear. We studied PD-L1 expression and the tumor immune microenvironment in dMMR CRC as a model of good responders to immunotherapy. We examined 35 dMMR and 34 mismatch repair-proficient (pMMR) CRCs using immune cell markers (CD3, CD4, CD8, CD20, CD68, and FOXP3) as well as programmed cell death receptor-1 (PD-1) and PD-L1 immunohistochemistry staining in whole tumor specimens and tissue microarray slides to compare 4 PD-L1 immunohistochemistry clones (SP142, E1L3N, 22C3, and 28.8). We observed no significant difference in PD-L1 expression between dMMR and pMMR CRCs. Only 2 dMMR tumors had membranous PD-L1 staining. Expression of PD-L1 was greater in stromal immune cells of dMMR CRC, which also contained more numerous intraepithelial (CD3+, CD8+, FOXP3+, and PD-1+) and stromal (CD8+, PD-1+) lymphocytes than did pMMR tumors. Immune cell quantification discriminated better between dMMR and pMMR tumors than did PD-L1 expression. Tumor heterogeneity and variations in PD-L1 expression were noted with different antibodies, especially for PD-L1+ immune cells, which were more numerous at the invasion margin. Given the poor correlation with mismatch repair status and technical limitations, the value of PD-L1 testing to accompany the development of anti-PD-1/PD-L1 immunotherapy remains unclear. Further clinical trials are required to determine which parameters are valuable predictive biomarkers of the response to immunotherapy among mismatch repair status, PD-L1 expression, and immune cell quantification in CRC.

Le Flahec G ，Badic B ，Guibourg B ，Doucet L ，Bail JP ，Marcorelles P ，Schick U ，Uguen A ... -  《-》