Description

Purpose

The purpose of this study is to learn more about the rate of CMV breakthrough in lung transplant patients who are CMV mismatched and receiving prophylaxis. The rates of negative side effects caused by the antiviral prophylaxis will also be monitored. For patients who do have a breakthrough of CMV viremia while on study the investigator will also evaluate the rate of resistance mutations.

Hypothesis

The investigator wants to demonstrate that breakthrough CMV DNAemia is common in CMV mismatch lung transplant recipients on ganciclovir/valganciclovir prophylaxis. In addition, the investigator will show that leukopenia and neutropenia related to prolonged prophylaxis is very common and discontinuation of ganciclovir/valganciclovir prophylaxis because of side effects explains most cases of breakthrough CMV DNAemia. The investigators findings will be relevant because they will answer the following questions:

1. Prophylaxis with ganciclovir/valganciclovir in mismatch lung transplant patients should include intensive CMV DNA monitoring.
2. Side effects related to the use of ganciclovir/valganciclovir can result in potential life-threatening infections due to the development of neutropenia and increased cost due to the use of granulocyte-colony stimulating factor.
3. Alternative prophylaxis with new antivirals with safer profile of side effects would result in a safer profile of adverse events. As resistance to ganciclovir may lead to death, the development of CMV infection in patients receiving antivirals targeting different enzymes than those targeted by ganciclovir/valganciclovir will not prevent future use of ganciclovir/valganciclovir to treat CMV infection or disease.

   Justification

Cytomegalovirus (CMV) infection is the most common opportunistic infection in lung transplantation leading to direct and indirect effects that can result in life threatening complications. The risk of CMV infection is highest in CMV seronegative lung recipients from CMV seropositive donor (CMV mismatch). Antiviral prophylaxis for 6 to12 months with valganciclovir is indicated in CMV mismatch lung transplant recipients according to International Guidelines. Despite prolonged antiviral prophylaxis, the risk of CMV infection post-prophylaxis is high in this group of patients. Valganciclovir was approved for antiviral prophylaxis in organ transplant patients in 2004. Rates of breakthrough CMV infection may be higher after 6 months of prophylaxis due to an increased risk of bone marrow toxicity and neutropenia from Valganciclovir that may lead to temporary prophylaxis discontinuation.

Resistance to ganciclovir is a major complication in all solid organ transplant patients, but lung transplant recipients are the subgroup of patients at highest risk. The rate of ganciclovir-resistant CMV infection in CMV mismatch lung transplant recipients is the highest among all organ transplants and its occurrence is associated with increased risk of death. Although CMV mismatch lung transplantation has been found to be a risk factor for ganciclovir-resistant CMV infection in most of the studies, the underlying pathophysiological mechanisms are not fully understood. Discontinuation of valganciclovir can lead to CMV replication with exposure to sub-therapeutic levels of ganciclovir in blood, and this may lead to the development of antiviral resistance.

Objectives

1. To evaluate the incidence of breakthrough CMV infection in CMV mismatch lung transplant patients receiving 6-12 months antiviral prophylaxis with ganciclovir/valganciclovir.
2. To evaluate the rates of leukopenia, neutropenia and antiviral prophylaxis discontinuation due to side effects of antiviral prophylaxis with ganciclovir/valganciclovir in CMV mismatch lung transplant patients.
3. To evaluate the rates of ganciclovir/valganciclovir resistance mutations in CMV DNA from mismatch lung transplant patients with breakthrough CMV viremia.

Research Method/Procedures:

This will be a prospective, multicenter, non-randomized, non-interventional study in 40 CMV mismatch lung transplant patients receiving standard of care prophylaxis according to each center. At baseline the patients medical history will be reviewed with them. Post transplant weeks 1 to 24 or 52 a CMV Polymerase chain reaction (PCR) will be done every two weeks. Standard of care blood work and the patients chart will be monitored to look for any relevant side effects or changes in medication. In case CMV viremia is detected during prophylaxis, the local PI can decide either to treat the CMV infection with therapeutic dose of antivirals (ganciclovir, valganciclovir or Foscarnet) or to maintain prophylaxis and CMV PCR monitoring. In all cases of CMV breakthrough viremia, a whole blood or plasma sample will be sent to Provincial Microbiology Lab in Edmonton to perform antiviral resistance by next-generation sequencing. From post transplant weeks 24 to 36 or 52 to 64 weekly CMV PCR will be done as per standard of care, all other standard of care blood work will also be monitored. Chart reviews will be completed to look for any relevant side effects.

Plan for Data Analysis:

For the analysis of data the investigator will have the support of the Northern Alberta Clinical Trials and Research Centre (NACTRC). Incidence rate of breakthrough CMV viremia, leukopenia, neutropenia and severe neutropenia will be calculated as number of case per 1,000 patients/week. The percentage of CMV infection post-prophylaxis in patients with and without breakthrough CMV infection will be compared by Fisher's exact test. Cox-regression analysis will be performed to identify independent variables associated with CMV breakthrough viremia.