ABSTRACT
BACKGROUND: Nonsurgical treatment options are increasingly needed for endometrial atypical hyperplasia (AH) and endometrioid endometrial cancer (EEC). Despite promising initial response rates, prospective long-term data and determinants for relapse are limited. METHODS: Follow-up data from patients in our prospective phase II trial of LIUD for AH/G1EEC were collected from medical records. Spatial transcriptomics (Nanostring GeoMX digital spatial profiling) with in silico cell type deconvolution and pathway analyses were employed on longitudinal biopsy samples from five patients across pre-treatment, on-treatment, and relapse. RESULTS: Of 43 participants exhibiting initial response to LIUD, 41 had follow-up data. Sixteen (39%) experienced relapse. Clinical factors associated with shorter response duration included younger age, initial diagnosis of G1EEC, lack of response at six months, premenopausal status, and Hispanic ethnicity (p<0.05), but only six-month response status remained a significant predictor in a multivariate model (p=0.023). LIUD increased abundance of NK cells (DMCP-counter score=46.13, FDR=0.004) and cytotoxic lymphocytes (DMCP-counter score=277.67, FDR=0.004), as well as lymphocyte cytotoxicity markers PRF1 (log2FC=1.62, FDR=0.025) and GZMA (log2FC=2.47, FDR=0.008). NK cells were reduced at relapse (DMCP-counter score=-55.96, FDR=0.02). Immune-related pathways (IFNα-response and TGFß-signaling) were enriched at relapse (FDR<0.05). IDO1 expression, reflecting immune exhaustion, was upregulated at relapse (FDR<0.05). CONCLUSIONS: Upfront resistance and relapse after initial response to LIUD for AH/G1EEC impacts nearly half of patients, remaining a major hurdle for non-surgical treatment of AH/G1EEC. Molecular studies evaluating longitudinal biopsies from a small cohort implicate immune mechanisms at relapse, including reversal of progestin-related immunomodulation and increased immune exhaustion.
ABSTRACT
Lynch syndrome (LS) is defined by inherited mutations in DNA mismatch repair genes, including MSH2, and carries 60% lifetime risk of developing endometrial cancer (EC). Beyond hypermutability, specific mechanisms for LS-associated endometrial carcinogenesis are not well understood. Here, we assessed the effects of MSH2 loss on EC pathogenesis using a novel mouse model (PR-Cre Msh2 flox/flox , abbreviated Msh2KO), primary cell lines established from this model, human tissues, and human EC cell lines with isogenic MSH2 knockdown. Beginning at eight months of age, 30% of Msh2KO mice exhibited endometrial atypical hyperplasia (AH), a precancerous lesion. At 12 to 16 months of age, 47% of Msh2KO mice exhibited either AH or ECs with histologic features similar to human LS-related ECs. Transcriptomic profiling of EC from Msh2KO mice revealed a transcriptomic signature for mitochondrial dysfunction. Studies in vitro and in vivo revealed mitochondrial dysfunction based upon two mechanisms: marked mitochondrial content reduction, along with pronounced disruptions to the integrity of retained mitochondria. Human LS-related ECs also exhibited mitochondrial content reduction compared with non-LS-related ECs. Functional studies revealed metabolic reprogramming of MSH2-deficient EC cells in vitro , including reduced oxidative phosphorylation and increased susceptibility to glycolysis suppression. We are the first to identify mitochondrial dysfunction and metabolic disruption as a consequence of MSH2 deficiency-related EC. Mitochondrial and metabolic aberrations should be evaluated as novel biomarkers for endometrial carcinogenesis or risk stratification and could serve as targets for cancer interception in women with LS. Significance: This is the first study to report mitochondrial dysfunction contributing to MSH2-deficient endometrial cancer development, identifying a noncanonical pathway for MSH2 deficient carcinogenesis, which also imparts vulnerability to metabolic targeting.
