A Study of the Drug Letermovir (LTV) as Prevention for Recurrent of Cytomegalovirus (CMV) Infection

Inclusion Criteria

• Age >/= 12 years (any weight)
• Have received allogenic HCT
• Have received preemptive therapy for clinically significant CMV infection post-HCT and have completed preemptive therapy no longer than 7 days prior to enrollment. Preemptive treatment includes ganciclovir, valganciclovir, foscarnet or cidofovir. Clinically significant CMV infection is defined as CMV viremia requiring preemptive therapy or CMV EOD. Patients who have received LTV prophylaxis prior to onset of clinically significant CMV infection prior to enrollment (see also exclusion criteria below).
• Have one or more risk factors for recurrent CMV infection:
• Human leukocyte antigen (HLA) mismatch
• HLA-related (sibling) donor with at least one mismatch at the HLA-A, -B or -DR gene loci
• Haploidentical donor
• Unrelated donor with at least one mismatch at the HLA-A, -B, -C or -DRC1gene loci, or
• Cord blood as stem cell source
• Acute or chronic GVHD requiring either topical steroids for gastrointestinal GVHD and/or systemic steroid treatment (>/= 1mg/kg/day of prednisone or equivalent dose of another corticosteroid) within 14 days prior to enrollment
• T-cell-depleted allograft ex-vivo or in-vivo T-cell depleting agents including but not limited to ATG, alemtuzimab and post HCT cyclophosphamide.
• For adult patients, able to provide written consent and complete the informed consent. For patients under 18 years, the patient's parent(s) or legal guardian(s) must provide informed consent and the patient must provide written assent to participation in the study.
• Willing and able to comply with trial instructions and requirements
• Male and female patients of childbearing potential must be willing to use a highly effective method of contraception for the course of the study. Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the patient.

Subject eligibility criteria for the observational cohort:

• Age 18 years or older
• First allogenic peripheral blood or marrow HCT
• LTV prophylaxis starting 800 mg twice daily), valacyclovir (doses of > 500mg twice daily), or famciclovir (doses > 500mg/day) for varicella zoster virus (VZV)/herpes simplex virus prophylaxis; limited treatment courses at higher doses for VZV infections are permissible if treatment duration dose not exceed 14 days total. Short courses of IV cidofovir for adeno virus (ADV) are permissible
• Suspected or known hypersensitivity to active or inactive ingredients of LTV formulations
• Patients treated with a medication whose administration with LTV is ontraindicated and whose discontinuation is not possible. Contraindicated medications include pimozide, ergot alkaloids and pitavastatin or simvastatin when co-administered with cyclosporine.
• Imminent demise (expected survival 0.5mg/kg for 2 weeks or longer) within 3 weeks prior to enrollment