Endometrial cancer (EC) is rising both in incidence and mortality, is involving younger women, and is leading in the US for gynecologic cancer incidence. The application of molecular characterization and targeting treatment to selected molecular types of EC is exemplified by the marked benefit of mismatch repair deficient (dMMR) EC to immune checkpoint inhibitor (ICI) treatment. However, the response to immunotherapy has been less significant in other EC molecular types. We reported previously on the public health relevance of molecular analysis of endometrial cancer types to direct treatment considerations and discussed the limitation in biomarkers predictive of response to immunotherapy or available to examine for treatment selection, outside of mismatch repair deficiency. The current follow-on commentary addresses how new thinking can lead to optimization of immunotherapy applications for endometrial cancer molecular types, how to consider timing and sequencing of immunotherapy with other interventions, and directions for novel immunotherapy combinations. This report outlines key background studies and preclinical observations, directions to overcome inherent resistance, how to leverage ICI to augment clinical response to standard treatments, and considerations for how and when to re-expose patients to ICI treatment(s). The discussions led to potential clinical trial concepts now under development.