This case indicates the potential existence of an endometrial cancer subtype that is sensitive to immune checkpoint blockade based on mechanisms other than those driven by MMR deficiency or PD-L1 positivity.
A higher prevalence of PD-L1-positive cases was observed among esophageal specimens compared with gastric ones (p = 0.0003), in high-grade and adenocarcinoma samples in comparison with low-grade dysplasia (p < 0.0001), and in lesions with mismatch repair deficiency (p = 0.028).
This review focuses on the recent development of biomarkers for assessing the efficacy of anti-PD1 antibodies using routine blood tests such as the neutrophil-to-lymphocyte ratio, eosinophil ratio, serum markers such as lactate dehydrogenase, programmed cell death ligand 1 (PD-L1) expression on melanoma cells, microsatellite instability and mismatch repair deficiency assays, as well as soluble CD163, and tumor-associated macrophage-related chemokines (e.g., CXCL5, CXCL10).
A positive association was identified for PD-L1 expression with mismatch repair deficiency and EBV status; however, no association was revealed with HER2 status.
However, the prognostic value of PD-L1 expression and the systemic inflammatory response for patients with MMR deficiency has not been fully investigated.
Pembrolizumab has been approved for relapsed cervical cancer with programmed death ligand 1 positivity and relapsed solid tumors with mismatch repair deficiency, which applies to 30% of endometrial cancers.
Two key biologically important predictive tissue biomarkers, specifically, PD-L1 and mismatch repair deficiency, have been FDA-approved in conjunction with the checkpoint inhibitor, pembrolizumab.
Although recent literature has been flooded with studies on ICI predictive biomarkers, available data show that currently approved companion diagnostics either leave out many possible responders, as in the case of PD-L1 testing for first-line metastatic lung cancer, or apply to a small subset of patients, such as the recently approved treatment for microsatellite instability-high or mismatch repair deficiency tumors.
A comprehensive miRNA screening using The Cancer Genome Atlas (TCGA) dataset (<i>n</i> = 260) combined with eight different miRNA target prediction programs resulted in the identification of a tumor suppressive miRNA, miR-148a-3p, as a potential negative regulator of PD-L1 expression, particularly in dMMR/MSI-H colorectal cancer.
PD-L1 was positive in 70%, epithelial IDO in 58%, stromal IDO in 91%, epithelial WARS in 67%, stromal WARS in 100%, epithelial GBP5 in 53% and stromal GBP5 in 71%.MMR-deficiency was found in 22%.
There is a biological rationale to evaluate immune-checkpoint inhibitors in refractory GCCs, as PD-L1 is often expressed and refractory tumors often display mismatch repair deficiency or microsatellite instability.
Tumor lymphocytic infiltration (TIL) and programed cell death ligand-1 (PD-L1) have been associated with prognosis in different malignancies while DNA mismatch-repair deficiency (MMR-D) has been associated with response to check-point inhibitors.
PD-L1 is expressed in a significant proportion of EC and is associated with mismatch repair deficiency, potentially representing a mechanism of tumor immune evasion and a therapeutic target in EC.