Relationship between MLH1, PMS2, MSH2 and MSH6 gene-specific alterations and tumor mutational burden in 1057 microsatellite instability-high solid tumors

Microsatellite instability-high (MSI-H) and tumor mutational burden (TMB) are predictive biomarkers for immune-checkpoint inhibitors (ICIs). Still, the relationship between the underlying cause(s) of MSI and TMB in tumors remains poorly defined. We investigated associations of TMB to mismatch repair (MMR) protein expression patterns by immunohistochemistry (IHC) and MMR mutations in a diverse sample of tumors. Hypothesized differences were identified by the protein/gene affected/mutated and the tumor histology/primary site. Overall, 1057 MSI-H tumors were identified from the 32 932 tested. MSI was examined by NGS using 7000+ target microsatellite loci. TMB was calculated using only nonsynonymous missense mutations sequenced with a 592-gene panel; a subset of MSI-H tumors also had MMR IHC performed. Analyses examined TMB by MMR protein heterodimer impacted (loss of MLH1/PMS2 vs. MSH2/MSH6 expression) and gene-specific mutations. The sample was 54.6% female; mean age was 63.5 years. Among IHC tested tumors, loss of co-expression of MLH1/PMS2 was more common (n = 544/705, 77.2%) than loss of MSH2/MSH6 (n = 81/705, 11.5%; P < .0001), and was associated with lower mean TMB (MLH1/PMS2: 25.03 mut/Mb vs MSH2/MSH6 46.83 mut/Mb; P < .0001). TMB also varied by tumor histology: colorectal cancers demonstrating MLH1/PMS2 loss had higher TMBs (33.14 mut/Mb) than endometrial cancers (20.60 mut/Mb) and other tumors (25.59 mut/Mb; P < .0001). MMR gene mutations were detected in 42.0% of tumors; among these, MSH6 mutations were most common (25.7%). MSH6 mutation patterns showed variability by tumor histology and TMB. TMB varies by underlying cause(s) of MSI and tumor histology; this heterogeneity may contribute to differences in response to ICI.     

Feasibility and safety of irreversible electroporation (IRE) in patients with small renal masses: Results of a prospective study

Background

Irreversible electroporation (IRE) has the potential to overcome limitations of thermal ablation, enabling small renal mass (SRM) ablation near vital structures.

Assessing the utility of yearly pre-season laboratory screening for athletes on a major professional sports team

Objectives

Professional athletes undergo annual pre-season laboratory screening, although clinical evidence supporting the practice is limited and no uniform set of guidelines on pre-season laboratory screening exists. The aim of this study was to assess the clinical value of annual pre-season laboratory screening tests for a major professional sports team over multiple years.

Bolus 5-fluorouracil (5-FU) In Combination With Oxaliplatin Is Safe and Well Tolerated in Patients Who Experienced Coronary Vasospasm With Infusional 5-FU or Capecitabine

Introduction

Coronary vasospasm associated with fluoropyrimidine (FP)-based chemotherapy is a potentially serious complication and reported to occur more often with infusional 5-fluorouracil (5-FU) or capecitabine than with bolus 5-FU. Given the additional benefit of oxaliplatin over FP alone in the management of colorectal cancer, retaining oxaliplatin in the treatment regimen is desirable, but the safety of combining bolus 5-FU with oxaliplatin in patients with FP-induced vasospasm is not well established. We performed a retrospective review to explore the safety of substituting FLOX (bolus 5-FU, oxaliplatin, leucovorin) for FOLFOX (infusional 5-FU, oxaliplatin, leucovorin) and CAPOX (capecitabine, oxaliplatin) in patients who had FP-induced coronary vasospasm.