Extension of Letermovir (LET) From Day 100 to Day 200 Post-transplant for the Prevention of Cytomegalovirus (CMV) Infection in Hematopoietic Stem Cell Transplant (HSCT) Participants (MK-8228-040)

Study Overview
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Brief Summary
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The purpose of this study was to evaluate the safety and efficacy of letermovir (LET) versus placebo when cytomegalovirus (CMV) prophylaxis was extended from 100 days to 200 days post-transplant in CMV seropositive participants who received an allogenic hematopoietic stem cell transplant (HSCT). It was hypothesized that LET is superior to placebo in the prevention of clinically-significant CMV infection when LET prophylaxis is extended from 100 to 200 days.

Official Title
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A Phase 3 Randomized, Double-blind, Placebo-controlled Clinical Trial to Evaluate the Safety and Efficacy of Letermovir (LET) Prophylaxis When Extended From 100 Days to 200 Days Post-transplant in Cytomegalovirus (CMV) Seropositive Recipients (R+) of an Allogenic Hematopoietic Stem Cell Transplant (HSCT)

Conditions
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Cytomegalovirus Infection

Intervention / Treatment
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* Drug: Letermovir
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: have documented positive CMV serostatus (CMV immunoglobulin G [IgG] seropositive) for recipient (R+) at the time of transplant has a history of allogeneic HSCT (bone marrow, peripheral blood stem cell, or cord blood transplant) within  100 days prior to randomization has undetectable CMV deoxyribonucleic acid (DNA) or detectable/not quantifiable CMV DNA from a plasma sample collected within 14 days prior to randomization has received LET as primary prophylaxis that started within 28 days of HSCT and continued through Week 14 post-transplant (± 1 week) prior to randomization is at high risk of CMV disease, defined as meeting one or more of the following criteria: has a related donor with at least 1 mismatch at 1 of the specified 3 human leukocyte antigen (HLA) gene loci (HLA-A, B, or DR) has an unrelated donor with at least one mismatch at one of the specified four HLA gene loci (HLA-A, B, C, and DRB1) has a haploidentical donor has umbilical cord blood as the stem-cell source has ex-vivo T-cell-depleted grafts has received anti-thymocyte globulin has received alemtuzumab has graft versus host disease (GVHD) or other conditions, requiring the use of systemic prednisone (or equivalent) at a dose of ≥1 mg/kg of body weight per day within 6 weeks of randomization for female participants, is not pregnant or breastfeeding, and is either not a woman of childbearing potential (WOCBP) or is a WOBCP who agrees to use acceptable contraception during the treatment period and for ≥28 days after the last dose of study drug. Exclusion Criteria: has a history of CMV end-organ disease or preemptive treatment therapy for CMV after HSCT prior to randomization has a history of >14 days total of LET interruption during the first 100 days post-transplant prior to randomization has suspected or known hypersensitivity to active or inactive ingredients of LET formulations has severe hepatic insufficiency defined as Child-Pugh Class C within 14 days prior to randomization. has serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >5× the upper limit of normal (ULN) within 14 days prior to randomization has end-stage renal impairment with a creatinine clearance less than 10 mL/min, as calculated by the Cockcroft-Gault equation using serum creatinine within 14 days prior to randomization has both moderate hepatic insufficiency AND moderate-to-severe renal insufficiency has an uncontrolled infection on the day of enrollment requires mechanical ventilation or is hemodynamically unstable at the time of enrollment has a documented positive result for a human immunodeficiency virus antibody (HIV-Ab) test at any time prior to screening, or for hepatitis C virus antibody (HCV-Ab) with detectable HCV ribonucleic acid (RNA), or hepatitis B surface antigen (HBsAg) within 6 months prior to screening. has active solid tumor malignancies with the exception of localized basal cell or squamous cell skin cancer or the condition under treatment (eg, lymphomas) has received cidofovir or CMV immunoglobulin with 30 days prior to screening is currently participating or has participated in a study with an unapproved investigational compound, monoclonal antibody, or device within 28 days or 5× half-life of the investigational compound or monoclonal antibody, whichever is longer, of initial dosing in this study has previously participated in this study or any other study involving LET, or is currently participating in any study involving administration of a CMV vaccine or another CMV investigational agent, or is planning to participate in a study of a CMV vaccine or another CMV investigational agent during the course of this study is pregnant or expecting to conceive, is breastfeeding, or plans to breastfeed from the time of consent through 28 days after the last dose of study therapy is expecting to donate eggs starting from the time of consent through 28 days after the last dose of study therapy has clinically relevant drug or alcohol abuse within 12 months of screening that may interfere with participant treatment, assessment, or compliance with the protocol as assessed by the investigator has a history or current evidence of any condition, therapy, lab abnormality, or other circumstance that might confound the results of the study, interfere with the participant's participation for the full duration of the study, or would be put at undue risk as judged by the investigator, such that it is not in the best interest of the participant to participate in this study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Letermovir<br>Participants who received HSCT transplant and 100 days of LET prophylaxis were randomized to an additional 100 days of LET (480 mg once daily alone or 240 mg once daily for participants on cyclosporin A) treatment. | Drug: Letermovir<br>* LET tablet or intravenous infusion at a total daily dose of 240 mg (when given with cyclosporin A) or 480 mg (when given alone).<br>* Other names: PREVYMIS™, MK-8228;|
| Placebo Comparator: Placebo<br>Participants who received HSCT transplant and 100 days of LET prophylaxis were randomized to an additional 100 days of placebo treatment. | Drug: Placebo<br>* Placebo was administered as tablets matched to LET or as inactive (saline or dextrose) intravenous infusion.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With Clinically Significant CMV Infection From Week 14 ( 100 Days) Post-transplant Through Week 28 ( 200 Days) Post-transplant | Clinically significant CMV infection is either the onset of probable or proven CMV end-organ disease or initiation of anti-CMV preemptive therapy (PET) with approved anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) based on documented CMV viremia and the clinical condition of the participant. Missing values were handled by the observed failure (OF) approach where failure was defined as all participants who develop clinically significant CMV infection or discontinue prematurely from the study with CMV viremia from week 14 ( 100 days) through week 28 post-transplant. It was hypothesized that LET is superior to placebo in the prevention of clinically significant CMV infection when LET prophylaxis is extended from 100 to 200 days. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants Experiencing ≥1 Adverse Events (AEs) From Week 14 ( 100 Days) Post-transplant Through Week 28 ( 200 Days) Post-transplant | An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Percentage of Participants Withdrawing From Study Drug Due to an AE From Week 14 ( 100 Days) Post-transplant Through Week 28 ( 200 Days) Post-transplant | An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Percentage of Participants With Clinically Significant CMV Infection From Week 14 Post-transplant Through Week 38 Post-transplant | Clinically significant CMV infection is either the onset of probable or proven CMV end-organ disease or initiation of anti-CMV PET with approved anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) based on documented CMV viremia and the clinical condition of the participant. Missing values were handled by the OF approach where failure was defined as all participants who develop clinically significant CMV infection or discontinue prematurely from the study with CMV viremia from week 14 ( 100 days) through week 38 post-transplant. | From Week 14 post-transplant to Week 38 post-transplant (approximately 24 weeks) | 
| Percentage of Participants With Clinically Significant CMV Infection From Week 14 Post-transplant Through Week 48 Post-transplant | Clinically significant CMV infection is either the onset of probable or proven CMV end-organ disease or initiation of anti-CMV PET with approved anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) based on documented CMV viremia and the clinical condition of the participant. Missing values were handled by the OF approach where failure was defined as all participants who develop clinically significant CMV infection or discontinue prematurely from the study with CMV viremia from week 14 ( 100 days) through week 48 post-transplant. | From Week 14 post-transplant to Week 48 post-transplant (approximately 34 weeks) | 
| Time to Onset of Clinically Significant CMV Infection From Week 14 Post-transplant to Week 28 Post-transplant | Clinically significant CMV infection is either the onset of probable or proven CMV end-organ disease or initiation of anti-CMV PET with approved anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) based on documented CMV viremia and the clinical condition of the participant. Time to onset of clinically significant CMV infection is the elapsed time from transplant to the onset of CMV end-organ disease or to the initiation of anti-CMV PET. Time to onset was determined from the Kaplan-Meier method for censored data. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Time to Onset of Clinically Significant CMV Infection From Week 14 Post-transplant to Week 48 Post-transplant | Clinically significant CMV infection is either the onset of probable or proven CMV end-organ disease or initiation of anti-CMV PET with approved anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) based on documented CMV viremia and the clinical condition of the participant. Time to onset of clinically significant CMV infection is the elapsed time from transplant to the onset of CMV end-organ disease or to the initiation of anti-CMV PET. Time to onset was determined from the Kaplan-Meier method for censored data. | From Week 14 post-transplant to Week 48 post-transplant (approximately 34 weeks) | 
| Percentage of Participants With CMV Viremia Who Started PET From Week 14 Post-transplant to Week 28 Post-transplant | The percentage of participants with CMV viremia who initiated PET of anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) was determined. Missing values were handled with the OF approach, where failure was defined as all participants who develop clinically significant CMV infection or discontinue prematurely from the study with CMV viremia from week 14 through week 28 post-transplant. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Percentage of Participants With CMV Viremia Who Started PET From Week 14 Post-transplant to Week 48 Post-transplant | The percentage of participants with CMV viremia who initiated PET of anti-CMV agents (ganciclovir, valganciclovir, foscarnet, and/or cidofovir) was determined. Missing values were handled with the OF approach, where failure was defined as all participants who develop clinically significant CMV infection or discontinue prematurely from the study with CMV viremia from week 14 through week 48 post-transplant. | From Week 14 post-transplant to Week 48 post-transplant (approximately 34 weeks) | 
| Percentage of Participants With All-cause Mortality From Week 14 Post-transplant to Week 28 Post-transplant | The percentage of participants who died due to any cause (all-cause mortality) from Week 14 to Week 28 was determined. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Percentage of Participants With All-cause Mortality From Week 14 Post-transplant to Week 48 Post-transplant | The percentage of participants who died due to any cause (all-cause mortality) from Week 14 to Week 48 was determined. | From Week 14 post-transplant to Week 48 post-transplant (approximately 34 weeks) | 
| Time to All-cause Mortality From Week 14 Post-transplant to Week 28 Post-transplant | Time to all-cause mortality is the time elapsed after Week 14 post-transplant and death due to any cause, and was determined from the Kaplan-Meier method for censored data. | From Week 14 post-transplant to Week 28 post-transplant (approximately 14 weeks) | 
| Time to All-cause Mortality From Week 14 Post-transplant to Week 48 Post-transplant | Time to all-cause mortality is the time elapsed after Week 14 post-transplant and death due to any cause, and was determined from the Kaplan-Meier method for censored data. | From Week 14 post-transplant to Week 48 post-transplant (approximately 34 weeks) |