Molecular Subtype Not Immune Response Drives Outcomes in Endometrial Carcinoma

PURPOSE: Tumors with high mutation load are thought to engender stronger immune responses, which in turn promote prolonged patient survival. To investigate this, we assessed tumor-infiltrating lymphocytes (TILs) and immunosuppressive factors across the 4 molecular subtypes of endometrial cancer, which have characteristic mutation rates ranging from low to ultra-high. EXPERIMENTAL DESIGN: mutant (POLE), p53 abnormal (p53abn), and p53 wild-type (p53wt). Immune markers (CD3, CD8, CD79a, CD138, PD-1, PD-L1, FoxP3, IDO-1) were quantified by multiplex IHC and tested for associations with ProMisE subtype, survival, and other clinicopathologic parameters. RESULTS: tumors were generally devoid of immunologic features and were more prevalent in p53abn and p53wt endometrial cancers, yet were also seen in MMRd and POLE subtypes. In multivariable models involving ProMisE subtype, T-cell markers, and TIL clusters, only ProMisE showed independent prognostic significance. CONCLUSIONS: .