Dataset Information

Exceptional Response to Pembrolizumab in a Mismatch Repair-Deficient Aggressive Prostate Cancer with Somatic EPCAM, MSH2, and MSH6 Co-Deletion: A Case Report.

ABSTRACT: Mismatch repair-deficient (dMMR) prostate cancer (PCa) is a rare (1-5%) but highly actionable molecular subgroup of PCa, vulnerable to immune checkpoint inhibitors. Our case of sporadic dMMR PCa due to large monoallelic co-deletion of EPCAM, MSH2, and MSH6 features a clinically aggressive disease presentation and a major response to pembrolizumab. We report a 65-year-old patient with primary metastatic PCa, Gleason score 5 + 5 = 10, with penile and lymph node metastases at diagnosis. Patient showed rapid progression on first-line ADT and enzalutamide. Tumor next-generation sequencing (NGS) revealed microsatellite instability and a tumor mutational burden of 40.8 mutations/megabase. Immunohistochemistry showed co-loss of MSH2 and MSH6. Review of NGS row data confirmed large monoallelic deletion in chromosome 2p, including EPCAM, MSH2, and MSH6. No germline alterations in mismatch repair genes were detected. Patient showed excellent response to pembrolizumab, which is still ongoing. We conclude that early molecular tumor profiling is essential to enable personalized management of advanced PCa, especially in patients with aggressive or atypical disease course.

SUBMITTER: Hoch D

PROVIDER: S-EPMC10622161 | biostudies-literature | 2023 Jan-Dec

REPOSITORIES: biostudies-literature

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Publications

Exceptional Response to Pembrolizumab in a Mismatch Repair-Deficient Aggressive Prostate Cancer with Somatic EPCAM, MSH2, and MSH6 Co-Deletion: A Case Report.

Hoch Dennis D Rabaglio Manuela M Grob Tobias T von Gunten Michael M Beyer Jörg J Akhoundova Dilara D

Case reports in oncology 20230101 1

Mismatch repair-deficient (dMMR) prostate cancer (PCa) is a rare (1-5%) but highly actionable molecular subgroup of PCa, vulnerable to immune checkpoint inhibitors. Our case of sporadic dMMR PCa due to large monoallelic co-deletion of EPCAM, MSH2, and MSH6 features a clinically aggressive disease presentation and a major response to pembrolizumab. We report a 65-year-old patient with primary metastatic PCa, Gleason score 5 + 5 = 10, with penile and lymph node metastas ...[more]

PMID: 37928863

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Project description:DNA mismatch repair (MMR) is an important postreplication process that eliminates mispaired or unpaired nucleotides to ensure genomic replication fidelity. In humans, Msh2-Msh6 and Msh2-Msh3 are the two mismatch repair initiation factors that recognize DNA lesions. While X-ray crystal structures exist for these proteins in complex with DNA lesions, little is known about their structures during the initial search along nonspecific double-stranded DNA, because they are short-lived and difficult to determine experimentally. In this study, various computational approaches were used to sidestep these difficulties. All-atom and coarse-grained simulations based on the crystal structures of Msh2-Msh3 and Msh2-Msh6 showed no translation along the DNA, suggesting that the initial search conformation differs from the lesion-bound crystal structure. We modeled probable search-mode structures of MSH proteins and showed, using coarse-grained molecular dynamics simulations, that they can perform rotation-coupled diffusion on DNA, which is a suitable and efficient search mechanism for their function and one predicted earlier by fluorescence resonance energy transfer and fluorescence microscopy studies. This search mechanism is implemented by electrostatic interactions among the mismatch-binding domain (MBD), the clamp domains, and the DNA backbone. During simulations, their diffusion rate did not change significantly with an increasing salt concentration, which is consistent with observations from experimental studies. When the gap between their DNA-binding clamps was increased, Msh2-Msh3 diffused mostly via the clamp domains while Msh2-Msh6 still diffused using the MBD, reproducing the experimentally measured lower diffusion coefficient of Msh2-Msh6. Interestingly, Msh2-Msh3 was capable of dissociating from the DNA, whereas Msh2-Msh6 always diffused on the DNA duplex. This is consistent with the experimental observation that Msh2-Msh3, unlike Msh2-Msh6, can overcome obstacles such as nucleosomes. Our models provide a molecular picture of the different mismatch search mechanisms undertaken by Msh2-Msh6 and Msh2-Msh3, despite the similarity of their structures.

Dataset Information

Exceptional Response to Pembrolizumab in a Mismatch Repair-Deficient Aggressive Prostate Cancer with Somatic EPCAM, MSH2, and MSH6 Co-Deletion: A Case Report.

Publications

Exceptional Response to Pembrolizumab in a Mismatch Repair-Deficient Aggressive Prostate Cancer with Somatic EPCAM, MSH2, and MSH6 Co-Deletion: A Case Report.

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