Pathology Core

PROJECT SUMMARY/ABSTRACT The Pathology Core will be co-led by Dr. Marisa Nucci, a pathologist with expertise in gynecologic neoplasia, and by Dr. Geoffrey Shapiro, who brings experience with biomarker development for DNA repair inhibitor-based preclinical and clinical work. The core will provide support for all of the projects, focused on targeting replication

stress and DNA damage response in women with advanced endometrial cancer, including (1) WEE1 inhibition in uterine serous or TP53-mutant uterine cancers; (2) combined ATR/PI3K inhibition in uterine cancers; and (3) induction of replication stress to activate the cGAS/STING pathway to generate anti-tumor immunity in uterine

cancers. The Core will ensure quality control of data generated from human and mouse tissues in each of the projects and carry out unbiased analyses of results utilizing proper controls. The goal of Aim 1 is to provide histologic assessment and confirmation of experimental models via the application of standard criteria for

endometrial cancer diagnosis, along with immunohistochemical analyses to confirm Mullerian origin and histologic subtype in both parental tumors and in organoid or patient-derived xenograft models generated from those tumors. Models will be assessed serially to ensure that they retain fidelity to the primary tumors from

which they were derived. The primary objective of Aim 2 is to analyze immunohistochemical biomarkers of DNA damage (g-H2AX, pKAP1), replication stress (pRPA, pKAP1), ATM deficiency, oncogene activation (cyclin E, MYC) and homologous recombination repair proficiency (RAD51 foci). The characterization of models and

tumors pre- and on-treatment with the WEE1 inhibitors adavosertib and ZN-c3 or with a combination of the PI3K inhibitor copanlisib and the ATR inhibitor elimusertib will determine if these biomarkers are predictive of response and will confirm target engagement by these agents. In Aim 3, models and primary tumors subjected to WEE1

and ATR inhibitor-based treatments will be interrogated for changes in the immune microenvironment using a validated multiple immunofluorescence platform that will quantify T-cell infiltrates and subtypes along with immune checkpoint protein expression. Changes in the immune microenvironment will be correlated with DNA

damage and replication stress biomarkers, activation of the cGAS/STING pathway and with clinical outcomes.