Inclusion Criteria:
1. Age ≥ 18 years at the time of informed consent
2. Ability to provide written informed consent and HIPAA authorization
3. Diagnosis of DCIS or stage I, II, or III breast cancer
4. Currently receiving adjuvant aromatase inhibitor therapy (anastrozole, letrozole or exemestane) for ≥ 4 weeks prior to enrollment Note: Concurrent use of ovarian suppression is allowed Note: Concurrent use of CDK4/6 inhibitors is not allowed due to cytopenia risk
5. New or worsening self-reported musculoskeletal pain that began or significantly worsened after initiation of AI therapy
6. BPI average pain score of ≥ 4 during screening
7. ECOG PS 0-2
8. Adequate organ function:
1. Absolute neutrophil count ≥1,500/µL
2. Hemoglobin ≥11.0 g/dL
3. Platelet count ≥100,000/µL
4. Serum creatinine ≤1.5× upper limit of normal (ULN) or eGFR ≥60 mL/min/1.73m2
5. Total bilirubin ≤1.5× ULN (except in patients with documented Gilbert's disease, who must have a total bilirubin \< 3.0 mg/dL)
6. AST and ALT ≤1.5× ULN
9. Must agree to maintain stable doses of any analgesic medications or other AIMSS related therapies during the study period Note: rescue doses of acetaminophen or ibuprofen allowed on a non-daily basis, unless not new
Exclusion Criteria:
1. Current or prior use of hydroxychloroquine or chloroquine within 6 months
2. Known hypersensitivity to hydroxychloroquine, chloroquine, or 4-aminoquinoline compounds
3. History of retinopathy or retinal vein occlusion issues Note: While there is an association between retinopathy and HCQ use, this occurs rarely and with long term use with higher cumulative doses that used here. Other clinical trials have not required retinal exam (example: CTO-TBCRC04627, approved by IU IRB)
4. History of congestive heart failure (any NYHA class)
5. QTc prolongation (\>450 msec) at screening or history of significant arrhythmias requiring treatment
6. Moderate to severe renal impairment (eGFR \<60 mL/min/1.73m2)
7. Use of a prohibited concomitant medication (refer to Section 6.3.2) that cannot be discontinued or changed to an alternate therapy
8. Known glucose-6-phosphate dehydrogenase (G6PD) deficiency
9. History of porphyria
10. History of psoriasis
11. History of antiepileptic medications
12. Known history of inflammatory arthritis (example: rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis) or connective tissue disease (example: systemic lupus erythematosus, scleroderma, polymyositis)
13. Recent initiation or dose change (within 4 weeks) of medications for pain management (NSAIDs, duloxetine, gabapentin, pregabalin, opioids) Note: Patients on stable doses for \>4 weeks are eligible
14. Patients currently receiving or planned to receive high dose systemic treatment with corticosteroids defined as: cortisone \>50mg; hydrocortisone \>40mg, prednisone \>10mg, methylprednisolone \>8mg or dexamethasone \>1.5mg; or another immunosuppressive agent Note: Topical or inhaled corticosteroids are allowed
15. Other active malignancy other than breast cancer requiring systemic therapy
16. Pregnant or lactating
17. Co-enrollment in another clinical trial Note: Patients may co-enroll in other clinical trial(s) if the trial(s) does not interfere with the objectives of this trial
18. Significant psychiatric illness, in the opinion of the investigator, that would limit compliance with study requirements
19. Any active suicidality or history of active suicidal ideation/behavior/attempt within 1 year prior to screening
20. Any other condition that, in the opinion of the investigator, would make the patient unsuitable for study participation
