Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are serious, life-changing blood cancers. Patients with MDS and AML commonly experience complications related to infection, which affect patient quality-of-life and can sometimes lead to hospitalization or death. The investigators will conduct a randomized controlled trial to evaluate the effectiveness and safety of levofloxacin (antibiotic) in MDS and AML patients to safely reduce the risk of infection. In this study 50% of patients will be randomized (like a flip of a coin) to receive levofloxacin and the other 50% will receive usual care (control). The primary objective of the trial is to demonstrate the feasibility of a pragmatic pilot trial necessary to inform our planned phase 3 trial. Additionally, the investigators will monitor both groups of patients to see if the investigators improve the risk and/or severity of infection. Levofloxacin is commonly used in other clinical settings but has not been studied in patients with MDS or AML receiving outpatient chemotherapy (ie, chemotherapy that can be given from clinic, rather than a hospital).

STUDY OBJECTIVES: The primary objective of this trial is to demonstrate the feasibility of a pragmatic pilot trial necessary to inform our planned phase 3 trial. TRIAL DESIGN: The investigators will conduct a 75-patient multicentre randomized open-label pilot feasibility trial evaluating levofloxacin versus usual care in patients diagnosed with myelodysplastic syndrome and acute myeloid leukemia receiving outpatient therapy. The intervention group will be levofloxacin 500mg orally daily over the 90-day trial period. Patients will take the levofloxacin daily regardless of their neutrophil count. The control group will be usual care and routine antibiotic prophylaxis is not permitted. OUTCOMES: Our primary outcome will assess the feasibility of a large, multicentre trial of antibiotic prophylaxis in patients with MDS and AML at risk for infectious complications. Our primary measure of feasibility will be the ability to enroll a median of 1 patient per site per month (10 patients / month when all sites are active). SITES AND DURATION: The investigators will initially enroll patients from 10-15 sites across Canada. The expected duration of enrollment is 2 years. SIGNIFICANCE: The trial will evaluate the feasibility of studying antibiotic prophylaxis to optimize supportive care and minimize disease-related complications in patients with MDS and AML. If antibiotic prophylaxis reduces infectious complications, the results of the trial will represent a paradigm shift in how outpatients with MDS and AML are supported and will directly impact practice throughout the world. The initial infrastructure established from this feasibility study will be leveraged to create platform trial infrastructure that will function as a patient-centred learning health system to advance knowledge and improve outcomes for patients with MDS and AML.

Inclusion Criteria:

Master platform inclusion criteria:

1. Age ≥ 18 years
2. Diagnosis of myelodysplastic syndrome, myelodysplastic/myeloproliferative neoplasm, or acute myeloid leukemia

MYELO-CAN ABX inclusion criteria:

1. Initiation of hypomethylating agent-based chemotherapy

Exclusion Criteria:

Master platform exclusion criteria:

1. Participant is deemed unlikely to survive >30 days (as determined by clinical team)
2. Participant unable to provide informed consent

MYELO-CAN ABX exclusion criteria:

1. Fever/infection within 1 month of chemotherapy initiation
2. C-difficile infection within 12 months of chemotherapy initiation
3. Known sensitivity/allergy to fluoroquinolones
4. History of tendon disorders related to fluoroquinolone administration
5. Seizure disorder
6. Myasthenia gravis
7. Pregnancy and/or breastfeeding