The study was terminated based results of other studies and use of the new vaccine.

The researchers are doing this study to find out whether the study drug hydroxychloroquine can prevent infection with the COVID-19 virus, compared with placebo, in people who are receiving radiation therapy for their cancer. The placebo used in this study is a tablet that looks the same as the study drug and is taken in the same way, but it does not contain any active ingredients.

Inclusion Criteria:

• Age ≥ 18

• ECOG 0-3

• For patients who have not started radiation at the time of screening: patients are required to have a plan in place for a minimum of 10 radiation treatments with or without concurrent systemic therapy

• For patients who have already started radiation at the time of screening: patients must complete enrollment such that they are able to receive at least 10 radiation treatments with hydroxychloroquine.

• Disease Site

• Mandatory inclusion criteria:

• No COVID-19 symptoms within 14 days of enrollment:

  • (Temp >38C in addition to sore throat, cough, wheezing, chest tightness, shortness of breath, body aches, chills, diarrhea, and anosmia)
  • If symptoms are present within 14 days of enrollment, patients with a negative COVID-19 PCR or COVID-19 serology assay are eligible for inclusion.

• No close contact with confirmed COVID-19 person

• Close contact defined as:

  • Within 6 feet for prolonged period
  • Cohabitating

• Optional laboratory criteria (Recommended if available)

  • Negative pre-treatment SARS-CoV-2 rapid antigen test result (within 1 week of enrollment)
  • Negative pre-treatment SARS-CoV-2 PCR test result (within 1 week of enrollment) using MSKCC laboratory or outside laboratory assay
  • Negative pre-treatment Standard Q COVID-19 IgM/IgG rapid serology result (within 1 week of enrollment)
  • Blood serum for SARS-CoV-2 serology tests (being validated by MSKCC)

• Disease site meets following criteria:

  • Head and Neck / High-Risk Skin Cancer
  • Lung Cancer
  • Breast Cancer
  • Prostate Cancer
  • Central Nervous System Tumors
  • Gastrointestinal System Cancer
  • Gynecologic cancer
  • Other disease sites permitted at PI discretion

Exclusion Criteria:

• Previous positive test for SARS-CoV-2

• Previous positive serology test for SARS-CoV-2

• Recent Chest CT meeting CT exclusion criteria

• Live in a skilled nursing facility with COVID-19 symptoms (Temp >38 C in addition to sore throat, cough, wheezing, chest tightness, shortness of breath, body aches or chills, diarrhea, anosmia)

• Known hypersensitivity to hydroxychloroquine or 4-aminoquinoline derivatives

• Pre-existing retinopathy

• Known chronic kidney disease, stage 4 or 5, or receiving dialysis

• Breast Feeding

• Tamoxifen

• Absolute neutrophil Count <1,000/ml at registration

• Concurrent use of any other quinine derivative

• Antiarrhythmic medications: amiodarone, sotalol, dofetilide, procainamide, quinidine, flecainide

• Glucose-6-phosphate dehydrogenase deficiency

• Pre-treatment corrected QT interval (QTc) ≥470 milliseconds**

• Prisoners

• Inability to participate

• Psoriasis

• History of suicidal ideation

• CT Criteria for Enrollment Exclusion (Optional - only for patients who received a diagnostic CT as part of standard of care or a thoracic CT as part of radiation simulation): All patients with COVID-19 typical radiographic findings on CT Chest as defined by the RSNA will be excluded. Patients with any NEW COVID-19 indeterminate radiographic findings on CT Chest that are concerning for COVID-19 will be excluded. COVID-19 indeterminate features are permitted if they can be demonstrated as STABLE on prior (>14 calendar days) CT Chest or PET/CT. If no prior comparison is available AND any intermediate or typical feature is present, the patient is not eligible.

• COVID-19 Atypical Features

  • Isolated lobar or segmental consolidation without GGO
  • Discrete small nodules (centrilobular, "tree-in-bud")
  • Lung cavitation
  • Smooth interlobular septal thickening with pleural effusion

• COVID-19 Indeterminate Features

  • Multifocal, diffuse, perihilar, or unilateral GGO with or without consolidation lacking a specific distribution and are non-rounded or non-peripheral
  • Few very small GGO with a non-rounded and non-peripheral distribution

• COVID-19 Typical Features

  • Peripheral, bilateral GGO with or without consolidation or visible intralobular lines ("crazy paving")
  • Multifocal GGO of rounded morphology with or without consolidation or visible intralobular lines ("crazy paving")
  • Reverse Halo sign or other findings of organizing pneumonia ** If pre-treatment QTC can be decreased to <470, the patient can be re-considered for trial.

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.