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Abemaciclib Alone or in Combination with Hydroxychloroquine for the Treatment of Patients with Breast Cancer, ABBY Trial

Trial Status: active

This phase II trial studies the side effects of abemaciclib alone or in combination with hydroxychloroquine in treating patients with breast cancer and to see how well they work in reducing or eliminating disseminated tumor cells in the bone marrow. Disseminated tumor cells are breast cancer cells that are asleep (dormant) in the bone marrow. There are multiple ways in which these cells stay alive and two of these mechanisms are inhibited by abemaciclib and hydroxychloroquine. First, dormant cancer cells need a protein pathway called CDK 4/6 to wake up from sleep and to survive as an active cancer cell. Abemaciclib works by blocking the CDK 4/6 protein and by doing so may limit the dormant cancer cell from waking up or surviving. Second, dormant cancer cells also use a process called "autophagy" to generate their own nutrition, which can allow them to stay asleep. Hydroxychloroquine has been shown to prevent autophagy, which leads to starvation of the cells. Because both abemaciclib and hydroxychloroquine work on the mechanisms that keep the dormant cells alive, giving abemaciclib alone or in combination with hydroxychloroquine may be able to eliminate disseminated tumor cells.