Heterogeneous fates of metastatic lesions linked to immune escape in an ovarian cancer patient

We present an exceptional responder case of a patient with high-grade serous ovarian cancer, treated with multiple chemotherapy regimens, who exhibited regression of some metastatic lesions with concomitant progression of other lesions during a treatment-free period. Using an immunogenomics approach, we found that progressing metastases were characterized by immune cell exclusion while regressing and stable metastases were infiltrated by CD8+ and CD4+ T-cells, exhibited oligoclonal expansion of specific T-cell subsets, and showed indications of neoepitope depletion. These findings imply that multiple distinct tumor immune microenvironments co-exist within a single individual and may explain in part the heterogeneous fates of metastatic lesions often observed in the clinic post therapy.