[Cytomegalovirus effects in solid organ transplantation and the role of antiviral prophylaxis]

Among CMV-positive renal transplant patients receiving non-T-cell depleting induction, the absence of CMV disease prevention is a safe strategy: A retrospective cohort of 372 patients

Cytomegalovirus (CMV) is the most common opportunistic pathogen affecting renal transplant recipients, especially in the first months. CMV-seropositive renal transplant recipients (CMV R+) are at intermediate risk for CMV disease, but this risk is enhanced among CMV R+ receiving T-cell depleting induction, compared to CMV R+ receiving non-depleting induction. In this second group, data in favor of prophylactic antiviral treatment with valganciclovir to reduce CMV disease is sparse. In this retrospective and multicentric trial, we included 372 CMV R+ transplanted between January 2012 and April 2015 and receiving non-depleting induction. During the first year following transplantation, CMV disease occurred in 5/222 patients (2.25%) in the prophylaxis group and 9/150 (6%) in the no-prophylaxis group (difference +3.7; 95% CI: 0.5-8; P = .002 for non-inferiority). The incidence of allograft rejection and other infectious diseases was similar between the two groups. Graft and patient survival were similar at the end of follow-up. In conclusion, the absence of prophylaxis did not appear to have a deleterious effect for CMV diseases among CMV R+ receiving non-depleting induction.

Immune Monitoring of Infectious Complications in Transplant Patients: an Important Step towards Improved Clinical Management

Immune reconstitution following organ transplantation is absolutely critical in preventing infectious complications. However, understanding the kinetics of immune reconstitution and its potential impact on the clinical management of transplant patients remains a significant challenge. Over the last decade, various platform technologies have emerged which have provided important insights into the immune reconstitution kinetics in transplant patients. However, many of these technologies are too complicated and cumbersome to implement in a clinical setting. In this issue of the Journal of Clinical Microbiology, Chiereghin et al. (J. Clin. Microbiol. 56:e01040-17, 2018, https://doi.org/10.1128/JCM.01040-17) report the results of their evaluation of the QuantiFERON-CMV (QFN-CMV) assay to assess human cytomegalovirus (CMV)-specific CD8⁺ T-cell immunity in heart transplant recipients as a prognostic tool. These studies showed that patients with absence of global immune reactivity in the QFN-CMV assay were at a higher risk of developing CMV after discontinuing antiviral prophylaxis. Furthermore, failure to reconstitute CMV-specific immunity after resolution of the first episode of viremia was associated with viral relapse. These observations, along with other recent clinical studies utilizing the QFN-CMV assay, demonstrate that systematic monitoring of antiviral immunity can be successfully used as a prognostic tool and also to guide changes to the clinical management of transplant patients.

Liquid chromatography tandem mass spectrometry quantitation of intracellular concentrations of ganciclovir and its phosphorylated forms

Ganciclovir (GCV) is prescribed for cytomegalovirus infection which is a major issue in immunodepressed patients. It is however characterized by hematological toxicity. A better understanding of GCV concentration-effects relationships implies the measurement of intracellular forms. The objective of this study was to develop a method to measure GCV and its derivatives in cells. A four-stage procedure was developed with the following strategy: (1) to separate into different fractions the different intracellular forms of GCV (GCV itself and its phosphorylated forms) by solid-phase extraction (SPE) from blood cells, (2) to dephosphorylate the different phosphorylated forms into GCV, (3) to perform a second SPE to desalt samples and concentrate GCV, and (4) to measure GCV concentrations in the different extracts using a triple-quadrupole, linear ion trap mass spectrometer. Finally, the procedure was tested in 17 patients receiving GCV. From lysed cells, the different forms of GCV were fractionated, the phosphorylated forms were eluted with different KCl solutions, and the obtained fractions were treated with acid phosphatase to transform the phosphorylated metabolites back into GCV. The method was validated from 5 to 500 μg L(-1) with a limit of detection of 1 μg L(-1). The whole procedure was validated according to the US Food and Drug Administration guidelines and successfully applied in 17 patients receiving GCV. The method liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) allowing the measurement of GCV and its phosphorylated forms in blood cells was developed and can be used in developing clinical studies to explore the role of these biomarkers in the event of toxicity.