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

This study is testing whether low doses of the drug avelumab (an immunotherapy), hydroxychloroquine (a drug that may prevent dormant cancer cells from hiding), or palbociclib (a targeted therapy) can eliminate remaining hidden breast cancer cells in the bone marrow in women with hormone-receptor-positive, HER2-negative breast cancer who have no obvious signs of recurrence. **You may be eligible if:** - You have stage II or III hormone receptor-positive, HER2-negative breast cancer - You have finished all primary treatment (surgery, chemotherapy, radiation) except ongoing hormone therapy - A bone marrow test found detectable tumor cells - You are currently on adjuvant hormone therapy and enrolled within 2–7 years of starting it - You are 18 or older **You may NOT be eligible if:** - You have a history of another invasive breast cancer - You have uncontrolled diabetes, active autoimmune disease, severe heart or lung disease, or liver cirrhosis - You have an abnormal heart rhythm (QTc over 480 ms) - You are pregnant or breastfeeding - You are on high-dose steroids or immunosuppressants Talk to your doctor to see if this trial is right for you.