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

Required: HER2 (ERBB2) negative (negative)

Required: ESR1 positive (positive)

Must have received: surgery — definitive

Patients must have completed all primary and adjuvant therapy (including surgery, chemotherapy, and radiation) with the exception of adjuvant endocrine therapy.

Must have received: chemotherapy — adjuvant

Patients must have completed all primary and adjuvant therapy (including surgery, chemotherapy, and radiation) with the exception of adjuvant endocrine therapy.

Must have received: radiation therapy — adjuvant

Patients must have completed all primary and adjuvant therapy (including surgery, chemotherapy, and radiation) with the exception of adjuvant endocrine therapy.

Must have received: endocrine therapy — adjuvant

Patients must be receiving adjuvant endocrine therapy at the time of enrollment. Patients are eligible to enroll within 2-7 years after initiation of adjuvant endocrine therapy.

Cannot have received: CDK4/6 inhibitor (palbociclib)

Exception: Patients may have received prior CDK4/6 inhibitor therapy with an agent other than Palbociclib. Patients must have discontinued CDK4/6 inhibitor at least 6 months prior to screening.

Patients may have received prior CDK4/6 inhibitor therapy with an agent other than Palbociclib. Patients must have discontinued CDK4/6 inhibitor at least 6 months prior to screening.

Cannot have received: endocrine therapy (tamoxifen)

Exception: Use of tamoxifen as adjuvant endocrine therapy during study treatment is not allowed on hydroxychloroquine arms due to the potential drug-drug interaction with hydroxychloroquine. However, patients on tamoxifen at the time of screening may enroll on the treatment trial if switched to an aromatase inhibitor at least 21 days prior to starting study therapy in the event patient is randomized to a hydroxychloroquine containing arm.

Use of tamoxifen as adjuvant endocrine therapy during study treatment is not allowed on hydroxychloroquine arms due to the potential drug-drug interaction with hydroxychloroquine. However, patients on tamoxifen at the time of screening may enroll on the treatment trial if switched to an aromatase inhibitor at least 21 days prior to starting study therapy in the event patient is randomized to a hydroxychloroquine containing arm.

Cannot have received: endocrine therapy

Exception: Patients on any other adjuvant endocrine therapy, including any investigational therapy, are ineligible.

Patients on any other adjuvant endocrine therapy, including any investigational therapy, are ineligible.