Combination Letermovir and Standard of Care Antiviral for Enhanced Antiviral Response in Cytomegalovirus Infection in Lung Transplant Recipients (CLEAR-CMV)

Combination Letermovir and Standard of Care Antiviral for Enhanced Antiviral Response in Cytomegalovirus Infection in Lung Transplant Recipients: A Pilot Trial

The primary objective of the CLEAR-CMV trial is to evaluate the efficacy of letermovir therapy plus standard of care (SOC) antiviral compared to SOC plus placebo in achieving clearance of CMV viremia by week 3 in lung transplant recipients with active CMV infection.

Study Overview

• Status: Recruiting
• Conditions: CMV; Lung Transplant Recipient
• Intervention / Treatment: Drug: Placebo; Drug: Valganciclovir/Ganciclovir; Drug: Letermovir

Detailed Description

Lung transplant recipients are particularly susceptible to CMV infection due to intensive immunosuppressive regimens required to prevent graft rejection. CMV viremia is associated with increased morbidity, including CMV pneumonitis, and may contribute to chronic lung allograft dysfunction (CLAD).Approximately 30-50% of lung transplant recipients develop CMV infection within the first year post-transplant, with higher rates in CMV-seronegative recipients receiving organs from seropositive donors (D+/R-).

Current standard treatment for CMV infection in transplant recipients involves ganciclovir or its oral prodrug, valganciclovir, which inhibit CMV DNA polymerase. While effective, prolonged use is associated with toxicities, including myelosuppression, and the emergence of resistant strains in some cases. Letermovir, a novel antiviral targeting the CMV terminase complex, has shown efficacy in CMV prophylaxis in hematopoietic stem cell transplant recipients, and in kidney transplant recipients. It has now been extensively studied for use in prophylaxis but there are limited data in treatment. It is an attractive drug in transplant recipients because it has an excellent safety profile and requires no dose adjustment for renal dysfunction. However, data on the use of letermovir for treatment (as opposed to prophylaxis) are more limited. A multicenter study of letermovir use for treatment showed reasonable response rates especially in patients with low viral loads. The use of combination therapy for CMV treatment represents an attractive option, as there is extensive experience with other viruses (e.g. HIV , HCV) to show that this strategy leads to improved response rates and lessens the emergence of antiviral resistance. The use of ganciclovir plus letermovir is attractive because they target two different viral enzymes and both have oral options facilitating outpatient treatment. The most recently published international CMV consensus guidelines reports that the use of combination antiviral therapy is a key research need.

The investigators plan to conduct a pilot trial to determine the efficacy of letermovir plus standard of care (SOC) antiviral therapy in clearing CMV infection. The trial will be conducted in compliance with the protocol, Good Clinical Practices (GCP) and the applicable regulatory requirements.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Atul Humar, MD, FRCPC; Phone Number: 416-340-4241; Email: atul.humar@uhn.ca

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5G 2C4
      • Recruiting
      • University Health Network, Toronto General Hospital
      • Contact: Ilona Bahinskaya, MSc, CCRP; Phone Number: 4328 416-340-4800; Email: Ilona.Bahinskaya@uhn.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Recipient of a lung transplant.
• Has confirmed CMV viremia with a viral load ≥ 1000 IU/mL and will receive or has just started SOC antiviral treatment in the past 72h as per the decision of the treating physician.

Exclusion Criteria:

• Renal failure with Creatinine clearance <15 mL/min or requiring dialysis
• Severe hepatic impairment (Child-Pugh Class C)
• Participating in another interventional clinical trial
• Combined transplant (e.g heart-lung, lung-liver)
• Known allergy or contraindication to any of the antiviral medications
• Known antiviral resistance.
• Patient receiving cyclosporin, pimozide or ergot alkaloids (due to significant drug interaction with letermovir).
• Patient receiving or expected to receive CMV immunoglobulin or IVIG during the initial three week treatment phase

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: SOC antiviral plus placebo; Patients will receive the standard of care (SOC) antiviral therapy along with a placebo drug. The placebo drug will be administered for three weeks, while the SOC antiviral duration and dosage will be at the discretion of the treating physician.	Drug: Placebo; Placebo will be dosed the same as letermovir: one tablet every 12 hours for the first 24 hours, then one tablet per day for total treatment duration of 21 days.; Drug: Valganciclovir/Ganciclovir; Ganciclovir or its oral prodrug, valganciclovir will be administered as the standard of care antiviral therapy. Its duration will be at the discretion of the treatment physician but is typically given until clearance of viremia. The clinical definition of viral clearance is one negative viral load or two viral loads one week apart that are <200 IU/mL
Experimental: SOC antiviral plus letermovir active drug; Patients will receive the standard of care (SOC) antiviral therapy in combination with letermovir. The letermovir active drug will be administered for three weeks, while the SOC antiviral treatment duration and dosage will be at the discretion of the treating physician.	Drug: Valganciclovir/Ganciclovir; Ganciclovir or its oral prodrug, valganciclovir will be administered as the standard of care antiviral therapy. Its duration will be at the discretion of the treatment physician but is typically given until clearance of viremia. The clinical definition of viral clearance is one negative viral load or two viral loads one week apart that are <200 IU/mL; Drug: Letermovir; Letermovir (480mg) will be given orally as a loading dose every 12 hours for the first 24 hours, then one tablet per day for a total treatment duration of 21 days. Letermovir treatment will be started within 72 hours of starting SOC antiviral treatment as per the decision of the treating physician.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of patients achieving clearance of CMV viremia by week 3, as measured by quantitative PCR.	Viral clearance is described by a plasma CMV viral load < 200 IU/mL, the UHN clinically used threshold	From time of enrollment until 3 weeks after enrolment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of patients achieving an undetectable viral load	The limit of detection for plasma CMV viral load is 35 IU/mL	At week 3 and by month 6 after enrolment
Proportion of patients achieving CMV viral load <137 IU/mL (lower limit of quantification of the assay)	Lower limit of viral quantitation	At week 3 from enrolment and at 6 months
Time to clearance of CMV viremia	Clearance of CMV viremia is defined as plasma CMV viral load < 200 IU/mL as measured by quantitative PCR	From enrolment until clearance of CMV viremia, up to 6 months after enrolment
Time to resolution of symptoms if present		From enrolment until clearance of symptoms, up to 6 months after enrolment
Development of antiviral resistance	Incidence of antiviral resistance development to letermovir or SOC antivirals at the discretion of the treatment physician	From enrolment until up to 6 months after enrolment
Incidence of adverse events	Incidence of adverse effects (e.g., myelosuppression, renal dysfunction) will be recorded for the duration of the study.	From enrolment until up to 6 months after enrolment
Proportion of patients with clinically significant CMV recurrence within 6months, as determined by quantitative PCR or symptomatic CMV disease	Clinically significant CMV recurrence will be determined by a qPCR viral load ≥1000 IU/mL or symptomatic CMV disease	From enrollment until 6 months.
Monthly enrollment rate as a measure of recruitment feasibility	The investigators will aim for a target enrollment rate of 2 participants per month	From start of enrollment until up to 6 months after the final patient is enrolled

Collaborators and Investigators

• Sponsor: University Health Network, Toronto

Study record dates

Study Major Dates

• Study Start (Actual): December 24, 2025
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): August 1, 2027

Study Registration Dates

• First Submitted: November 13, 2025
• First Submitted That Met QC Criteria: November 17, 2025
• First Posted (Actual): November 19, 2025

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 12, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Lung Transplant; CMV Disease
• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Guanine; Hypoxanthines; Purinones; Purines; Acyclovir; Valganciclovir; Ganciclovir; letermovir
• Other Study ID Numbers: 25-5760

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No