Avelumab or Hydroxychloroquine With or Without Palbociclib to Eliminate Dormant Breast Cancer

The overarching goal of this clinical trial is to reduce the incidence of incurable recurrent metastatic breast cancer by targeting the precursors of these recurrences, bone marrow disseminated tumor cells (DTCs) present after definitive treatment. This trial targets unique mechanisms by which DTCs maintain a dormant phenotype (autophagy) and by which they escape dormancy (upregulation of the cyclin-dependent kinase4/6 (CDK4/6) pathway and microenvironmental factors such as immune evasion). The selection of these agents is based upon strong preclinical data demonstrating the relevance of autophagy (inhibited by HCQ), the CDK4/6 pathway (inhibited by palbociclib) and the programmed cell death-1 (PD-1)/Programmed death-ligand 1 (PD-L1) immune checkpoint pathway (blocked by avelumab) as critical mechanisms of cellular and immunological tumor dormancy. The phase II trial is designed to provide "proof of concept" and estimates of effect of various combinations and durations of these therapies on bone marrow DTCs as a surrogate for ultimate reduction in recurrence. The correlative science aims will provide additional insight into the relationship between the primary tumor and both the biology of DTCs and host immune surveillance for target validation and development, as well as evaluate the role of additional biomarkers both in the bone marrow (with a novel flow-based assay), and in the peripheral circulation (including both circulating tumor cells and cell-free DNA), to identify patients with minimal residual disease (MRD) and targets for intervention and measurement of DTC response.