Relationship Between Body Weight and Leukopenia in Non-Kidney Solid Organ Transplant Recipients With Normal Renal Function Who Are Receiving Valganciclovir for CMV Prophylaxis

BACKGROUND

Cytomegalovirus (CMV) disease causes significant morbidity among solid organ transplant (SOT) recipients. To prevent CMV disease, eligible recipients are frequently started on valganciclovir (VGC) prophylaxis post-transplant. Leukopenia has been documented as a primary adverse events of the drug (1). This study's primary aim was to determine whether a patient's weight at the start of VGC prophylaxis was associated with the development of leukopenia.

METHODS

This was a single center, retrospective cohort study that included adults > 18 years of age, who had received an organ transplant (heart, liver, or lung) at an academic transplant center from January 1, 2018 through December 31, 2022. A creatinine clearance of > 60 mL/min was required.

RESULTS

All 294 included patients received 900 mg/day of VGC for CMV prophylaxis, without dose adjustment. Fifty-two percent of the patients developed leukopenia while receiving VGC prophylaxis. The mean weight at initiation of VGC was higher in patients who did not develop leukopenia (97.9 kg) compared to those who did (90.7 kg; p = 0.0112). It was found that with each 1 kg increase in body weight, the likelihood of developing leukopenia decreased by 1.7% (p = 0.004, odds ratio = 0.983, 95% confidence interval [CI], 0.972-0.994). Patients with a baseline body-mass index (BMI) > 25 had a longer median freedom time from leukopenia after initiation of VGC as compared to the group with baseline BMI < 25 (log-rank p = 0.035).

CONCLUSION

These data suggest that in SOT recipients with normal renal function, receiving a fixed dose of VGC resulted in a significant, inverse relationship between body weight and the development of leukopenia.

Kidney function assessment using cystatin C and serum creatinine in heart transplantation recipients: Implications for valganciclovir dosing

BACKGROUND

Among heart transplantation (HT) recipients, the accuracy of serum creatinine (sCr)-based estimated glomerular filtration rate (eGFR) may be limited by fluctuations in muscle mass. Cystatin C (cysC) is less influenced by muscle mass, but its levels may increase with obesity and steroid use. Herein, we (1) longitudinally compared eGFRcysC and eGFRsCr among HT recipients; (2) investigated the association of body mass index (BMI), steroid use, and muscle mass with discrepancies between eGFRs; and (3) explored the implications of eGFRcysC use on valganciclovir (VGC) dosing.

METHODS

cysC and sCr were measured in 294 blood samples obtained from 80 subjects. Intraindividual differences between eGFRs (eGFRdiffcysC-sCr) were calculated with negative values corresponding to eGFRsCr > eGFRcysC and positive values to eGFRcysC > eGFRsCr. In a patient subset (n = 21), pectoralis muscle measures were obtained.

RESULTS

Marked differences between eGFRcysC and eGFRsCr were observed, particularly early post-HT (1-week post-HT, median eGFRdiffcysC-sCr -28 ml/min/1.73 m2). eGFRcysC demonstrated stability following a transient postoperative decline, while eGFRsCr decreased in the first year post-HT. Lower BMI and higher prednisone dose displayed a modest association with more negative eGFRdiffcysC-sCr values. Pectoralis muscle measures indicative of greater muscle mass and better tissue quality exhibited a stronger association with more positive eGFRdiffcysC-sCr values. The use of eGFRcysC would have led to VGC dose adjustment in 46% of samples, predominantly resulting in dose reduction.

CONCLUSIONS

Among HT recipients, eGFRcysC and eGFRsCr markedly differ with implications for VGC dosing. The observed discrepancies may reflect changes in body composition and steroid use.

Impact of early surgical complications on kidney transplant outcomes

BACKGROUND

Kidney transplantation (KT) improves clinical outcomes of patients with end stage renal disease. Little has been reported on the impact of early post-operative surgical complications (SC) on long-term clinical outcomes following KT. We sought to determine the impact of vascular complications, urological complications, surgical site complications, and peri-graft collections within 30 days of transplantation on patient survival, graft function, and hospital readmissions.

METHODS

We conducted a single-centre, observational cohort study examining adult patients (≥ 18 years) who received a kidney transplant from living and deceased donors between January 1st, 2005 and December 31st, 2015 with follow-up until December 31st, 2016 (n = 1,334). Univariable and multivariable analyses were performed with Cox proportional hazards models to analyze the outcomes of SC in the early post-operative period after KT.

RESULTS

The cumulative probability of SC within 30 days of transplant was 25%, the most common SC being peri-graft collections (66.8%). Multivariable analyses showed significant relationships between Clavien Grade 1 SC and death with graft function (HR 1.78 [95% CI: 1.11, 2.86]), and between Clavien Grades 3 to 4 and hospital readmissions (HR 1.95 [95% CI: 1.37, 2.77]).

CONCLUSIONS

Early SC following KT are common and have a significant influence on long-term patient outcomes.

Real world experience with conversion from valganciclovir to letermovir for cytomegalovirus prophylaxis: Letermovir reverses leukopenia and avoids mycophenolate dose reduction

PURPOSE

Valganciclovir (VGC) is the gold-standard for cytomegalovirus (CMV) prophylaxis (PPX) after solid organ transplant (SOT). Letermovir (LTV) was recently approved in high-risk kidney transplant and has reduced myelosuppressive toxicity. Conversion from VGC to LTV may be pursued in the setting of leukopenia. It is unknown if this strategy is effective.

METHODS

Adult patients receiving abdominal SOT were included if converted from VGC to LTV between January 1, 2018 and January 31, 2023. Primary objective was to describe the impact of LTV conversion as measured by WBC recovery, mycophenolate modification, and use of GCSF, and prophylaxis efficacy assessed by course completion and breakthrough DNAemia. Secondary objective was to evaluate rates of post-prophylaxis CMV.

RESULTS

Seventy five SOT recipients met inclusion criteria. Mean change in WBC in response to LTV conversion by day 14 was +2.02 ± 2.52 k/uL. 75%(56/75) of the population did not require mycophenolate adjustment or had their dose increased after conversion. GCSF was required in 38.7%(29/75) prior to conversion; only 21.3%(16/75) of patients required GCSF after conversion. Early termination was uncommon, 14.7%(11/75) stopped due to lack of ongoing insurance approval, only one patient stopped due to adverse effects (1.3%). One patient had clinically significant breakthrough (1.3%) that was successfully managed with VGC. Incidence of post prophylaxis CMV was 40%.

CONCLUSION

Withholding of VGC with LTV conversion may improve leukopenia without need for additional supportive measures. Most importantly, this strategy avoided additional mycophenolate modifications. In our study, LTV was associated with low rates of breakthrough. Post-prophylaxis CMV was similar to VGC prophylaxis.

Gaining consensus around patient risk groups and prognostic profiles to guide CMV management among patients with solid organ transplant: Insights from a Delphi panel with SOT experts

INTRODUCTION

This study aimed to characterize patient risk groups and respective prognostic profiles to optimize clinical decision-making and guide appropriate medical cytomegalovirus (CMV) management among patients with solid organ transplant (SOT).

METHODS

Between September 2021 and February 2022, a three-round modified Delphi study was conducted to generate consensus among 14 international experts in virology and organ transplantation. Experts were asked about treatment and prognoses for patients in seven distinct clinical scenarios. Furthermore, experts were asked to risk-stratify patients by pre-/post-transplant characteristics. Consensus around opting for/against a treatment was observed if ≥75% or <25% of experts reported ≥50% likelihood to recommend or if treatments were ranked inside/outside the top two options and ≥75% of experts were within 1 standard deviation of the mean rank.

RESULTS

Experts agreed on several unmet needs in CMV disease management post-SOT, particularly avoidance of treatment-limiting toxicities with conventional CMV therapy and emergence of both primary refractory and drug resistant treatment failures. Experts considered CMV viral load, resistance profile, and route of administration as critical to treatment selection. For newer CMV therapeutic options, experts listed lack of long-term use data, concerns over potential resistance, high cost and limited availability as challenges restricting adoption, and successful patient management.

CONCLUSION

Experts achieved consensus around patient risk stratifications and factors influencing therapeutic options. Recommendations emerging from this Delphi study may support practicing physicians when confronted with challenging CMV scenarios in SOT patients, but additional experiences with newer anti-CMV agents are needed to re-validate expert consensus and update post-transplant CMV guidelines.

Burden of neutropenia and leukopenia among adult kidney transplant recipients: A systematic literature review of observational studies

BACKGROUND

Leukopenia and neutropenia (L/N) may affect treatment decisions, potentially resulting in poor clinical and economic outcomes among kidney transplant recipients (KTRs). The burden of L/N is poorly quantified systematically. This systematic literature review aimed to summarize the incidence of, risk factors for, and clinical and economic outcomes associated with L/N post-KT.

METHODS

We systematically searched MEDLINE, Embase, and the Cochrane Library (from database inception-June 14, 2021) and conferences (past 3 years) to identify observational studies examining epidemiology, risk factors, or outcomes associated with L/N among adult KTRs.

RESULTS

Of 2081 records, 82 studies met inclusion criteria. Seventy-three studies reported the epidemiology of L/N post-KT. Pooled incidence of neutropenia, defined as absolute neutrophil counts (ANC) <1000/μl, ranged from 13% to 48% within 1-year post-transplant; ANC <500/μl ranged from 15% to 20%. Leukopenia, defined as white blood cell counts <3500/μl, was 19% to 83%. Eleven studies reported independent risk factors associated with L/N post-KT. D+/R- cytomegalovirus status, mycophenolic acid (MPA), and tacrolimus use were the most consistent risk factors across studies. Fourteen studies reported L/N-associated clinical outcomes. We noted a trend toward a positive association between neutropenia and acute rejection/opportunistic infections. Mixed findings were noted on the association between L/N and graft failure or mortality. Dosage modifications of valganciclovir, MPA, cotrimoxazole, and anti-thymoglobulin and the need for granulocyte colony-stimulating factor (G-CSF) use were common with L/N.

CONCLUSION

Findings suggest post-transplant L/N were common and associated with frequent modifications of immunosuppressive agents, requiring G-CSF use, and rejection or opportunistic infections. Findings highlight the need for interventions to reduce risk of L/N post-KT.

Outcomes among CMV-mismatched and highly sensitized kidney transplants recipients who develop neutropenia

Limited data exist on the incidence and clinical outcomes of neutropenia among kidney transplant recipients. Our study included 572 adults who received a kidney transplant at the University of California, San Francisco Medical Center between 2012 and 2018, and were CMV-mismatched or had a PRA ≥ 80%. Recipients with HIV, Hepatitis B and C, and primary non-function were excluded. Participants were followed for at least one year after transplantation. Neutropenia was defined as absolute neutrophil count < 1000 cells/μL. Cox proportional hazards regression models using neutropenia as a time-varying predictor were used to determine the risk of mycophenolic acid and valganciclovir changes, rejection, hospitalizations and use of granulocyte colony stimulating factor. Models were adjusted for demographics and transplant characteristics. Mean follow-up was 3.7 (SD, 1.8) years. The mean age of the cohort was 50.4 (13.1) years, and 57.5% were female. A total of 208 (36.3%) participants had neutropenia. Neutropenia was associated with an increased risk of valganciclovir or MPA dose reductions or discontinuations [adjusted hazard ratio, aHR: 7.78, 95% CI: 4.73- 12.81], rejection [aHR 2.00, 95% CI: 1.10-3.64] and hospitalizations [aHR 3.32, 95% CI: 2.12-5.19]. Neutropenia occurs frequently after kidney transplantation and leads to more medication changes and adverse clinical outcomes. This article is protected by copyright. All rights reserved.

Safety of Valganciclovir 450 mg 3 Times Weekly for Cytomegalovirus Prophylaxis in Solid Organ Transplant Recipients Requiring Hemodialysis

Background

Valganciclovir is the most commonly used antiviral for cytomegalovirus (CMV) prophylaxis in solid organ transplant recipients. However, there are limited clinical outcomes-supported data available to guide valganciclovir dosing in patients on hemodialysis (HD). This study aimed to assess the safety of our institution's current dosing strategy of valganciclovir 450 mg 3 times weekly post-HD.

Methods

This was a single-center retrospective review of all adult nonkidney transplant recipients between May 2016 and June 2018. Patients with end-stage renal disease requiring HD for >28 days posttransplant receiving valganciclovir 450 mg 3 times weekly post-HD were matched with non-HD patients receiving valganciclovir prophylaxis dosed per renal function. The primary endpoints were incidence of leukopenia, neutropenia, and thrombocytopenia while on valganciclovir prophylaxis.

Results

A total of 465 nonkidney transplants were performed during the study period, with 37 patients included in the HD group who were matched to 111 control patients in the non-HD group. Liver transplant recipients comprised 84% and 72% of each group, with none being CMV D+/R-. The rates of leukopenia (51.4% vs 51.4%, P = 1.00), severe neutropenia (absolute neutrophil count <500 cells/µL, 15.8% vs 14.0%, P = .85), and thrombocytopenia (24.3% vs 20.7%, P = .64) were similar in both HD and non-HD groups. There were no cases of CMV infection while on valganciclovir prophylaxis in either group.

Conclusions

Valganciclovir 450 mg 3 times weekly was found to have similar rates of leukopenia, neutropenia, thrombocytopenia, and CMV infection in comparison to valganciclovir dosed per renal function in non-HD transplant recipients.

Predictors and Complications of Post Kidney Transplant Leukopenia

BACKGROUND

Leukopenia occurs frequently following kidney transplantation and is associated with adverse clinical outcomes including increased infectious risk. In this study we sought to characterize the causes and complications of leukopenia following kidney transplantation.

METHODS

In a cohort of adult patients (≥18 years) who underwent kidney transplant from Jan 2006-Dec 2017, we used univariable Cox proportional Hazards models to identify predictors of post-transplant leukopenia (WBC < 3500 mm³). Factors associated with post-transplant leukopenia were then included in a multivariable backwards stepwise selection process to create a prediction model for the outcome of interest. Cox regression analyses were subsequently used to determine if post-transplant leukopenia was associated with complications.

RESULTS

Of 388 recipients, 152 (39%) developed posttransplant leukopenia. Factors associated with leukopenia included antithymocyte globulin as induction therapy (HR 3.32, 95% CI 2.25-4.91), valganciclovir (HR 1.84, 95% CI 1.25-2.70), tacrolimus (HR 3.05, 95% CI 1.08-8.55), prior blood transfusion (HR 1.17 per unit, 95% CI 1.09- 1.25), and donor age (HR 1.02 per year, 95% CI 1.00-1.03). Cytomegalovirus infection occurred in 26 patients with leukopenia (17.1%). Other than cytomegalovirus, leukopenia was not associated with posttransplant complications.

CONCLUSION

Leukopenia commonly occurred posttransplant and was associated with modifiable and non-modifiable pretransplant factors.

Evaluation of cytomegalovirus prophylaxis in low and intermediate risk kidney transplant recipients receiving lymphocyte-depleting induction

Cytomegalovirus (CMV) is a significant cause of morbidity in kidney transplant recipients (KTR). Historically at our institution, KTR with low and intermediate CMV risk received 6 months of valganciclovir if they received lymphocyte depleting induction therapy. This study evaluates choice and duration of CMV prophylaxis based on donor (D) and recipient (R) CMV serostatus and the incidence of post-transplant CMV viremia in low (D-/R-) and intermediate (R+) risk KTR receiving lymphocyte-depleting induction therapy. A protocol utilizing valacyclovir for 3 months for D-/R- and valganciclovir for 3 months for R+ was evaluated. Adult D-/R- and R+ KTR receiving anti-thymocyte globulin, rabbit or alemtuzumab induction from 8/20/2016 to 9/30/2018 were evaluated through 1 year post-transplant. Patients were excluded if their CMV serostatus was D+/R-, received a multi-organ transplant, or received basiliximab. Seventy-seven subjects met the inclusion criteria: 25 D-/R- (4 historic group, 21 experimental group) and 52 R+ (31 historic, 21 experimental). No D-/R- patients experienced CMV viremia. Among the R+ historic and experimental groups, there was no significant difference in viremia incidence (35.5% vs 52.4%; P = .573). Of these cases, the peak viral load was similar between the groups (median [IQR], 67 [<200-444] vs <50 [<50-217]; P = .711), and there was no difference in the incidence of CMV syndrome (16.1% vs 14.3%; P = 1.000) or CMV related hospitalization (12.9% vs 14.3%; P = 1.000). No patient experienced tissue invasive disease. These results suggest limiting valganciclovir exposure may be possible in low and intermediate risk KTR receiving lymphocyte-depleting induction therapy with no apparent impact on CMV-related outcomes.

Emerging Role of Compartmentalized G Protein-Coupled Receptor Signaling in the Cardiovascular Field

G protein-coupled receptors (GPCRs) are cell surface receptors that for many years have been considered to function exclusively at the plasma membrane, where they bind to extracellular ligands and activate G protein signaling cascades. According to the conventional model, these signaling events are rapidly terminated by β-arrestin (β-arr) recruitment to the activated GPCR resulting in signal desensitization and receptor internalization. However, during the past decade, emerging evidence suggest that many GPCRs can continue to activate G proteins from intracellular compartments after they have been internalized. G protein signaling from intracellular compartments is in general more sustained compared to G protein signaling at the plasma membrane. Notably, the particular location closer to the nucleus is beneficial for selective cellular functions such as regulation of gene transcription. Here, we review key GPCRs that undergo compartmentalized G protein signaling and discuss molecular considerations and requirements for this signaling to occur. Our main focus will be on receptors involved in the regulation of important physiological and pathological cardiovascular functions. We also discuss how sustained G protein activation from intracellular compartments may be involved in cellular functions that are distinct from functions regulated by plasma membrane G protein signaling, and the corresponding significance in cardiovascular physiology.

A Comparison of Different Valgancyclovir Formulations in the Universal 6-Month Prophylaxis Against CMV Infection in Renal Transplant Recipients: A Randomized Single-Centre Study

INTRODUCTION

Cytomegalovirus (CMV) is the most common opportunistic infective pathogen in kidney transplant recipients. Valganciclovir (VAL) is commonly used for prophylaxis, especially in high-risk recipients. Generic VAL formulations have become available, but the data about their safety and efficacy are lacking.

METHODS

Consecutive de novo kidney transplant patients were randomized to generic VAL Valganciklovir Teva® (VT group)(24 patients) or Alvanocyte® (A group), Alvogen (19 patients) or to Valcyte® (V group), Roche (23 patients) in a 18-month open-label study. Universal prophylaxis was used for 6 months after the transplantation. CMV DNA levels were measured at 1,3,6,9,12 and 18 months after the transplantation. All positive measurements of CMV DNA were recorded.

RESULTS

Groups did not differ regarding the clinical characteristics or the risk for developing CMV infection in the post-transplant period. CMV replications were most common at 9 months after the transplantation with rates of 9% for the V, 13% for the VT and 26% for the A group (p=0.26). At 12 months, positive CMV DNA was recorded in 22%, 8% and 11 % of patients taking V, VT and A, respectively (p=0.37). Rates of biopsy-proven acute rejection, adverse events, and serious adverse events were similar for all formulations. Lymphocele occurred most commonly in the V group (35%) compared to 17% in VT and 17% in the A group (p=0.23). One patient from each of the A and VT groups developed CMV disease. Additionally, they were the only two patients with CMV DNA copies above 656 IU/ml. Glomerular filtration rates were similar in all groups at all time points, while proteinuria was significantly higher at 12 months in patients who received V 0.32 g/day (0.18 - 0.42), compared to patients on VT 0.2 (0.1 - 0.2), or A 0.2 (0.2 - 0.3), p=0.04.

CONCLUSION

Valgancyclovir efficacy and safety in this limited data set is similar with early administration of V, VT and A after kidney transplantation. Additional studies aimed at elucidating the effectiveness of this treatment regimen in patients who are at high risk for developing CMV infection are necessary to draw further conclusions.

High frequency of valganciclovir underdosing for cytomegalovirus prophylaxis after renal transplantation

Background

The correct valganciclovir dose for cytomegalovirus (CMV) prophylaxis depends on renal function estimated by the Cockcroft–Gault (CG) estimated creatinine clearance (CG-CrCl) formula. Patients with delayed or rapidly changing graft function after transplantation (tx) will need dose adjustments.

Methods

We performed a retrospective investigation of valganciclovir dosing in renal transplant patients receiving CMV prophylaxis between August 2003 and August 2011, and analysed valganciclovir dosing, CG-CrCl, CMV viraemia (CMV-PCR <750 copies/mL), leucopenia (<3500/µL) and neutropenia (<1500/µL) in the first year post-transplant. On Days 30 and 60 post-transplant, dosing pattern in relation to estimated creatinine clearance was analysed regarding CMV viraemia, leucopenia and neutropenia.

Results

Six hundred and thirty-five patients received valganciclovir prophylaxis that lasted 129 ± 68 days with a mean dose of 248 ± 152 mg/day of whom 112/635 (17.7%) developed CMV viraemia, 166/635 (26.1%) leucopenia and 48/635 (7.6%) neutropenia. CMV resistance within 1 year post-transplant was detected in three patients. Only 137/609 (22.6%) patients received the recommended dose, while n = 426 (70.3%) were underdosed and n = 43 (7.1%) were overdosed at Day 30 post-tx. Risk factors for CMV viraemia were donor positive D (+)/receptor negative R (−) status and short prophylaxis duration, but not low valganciclovir dose. Risk factors for developing leucopenia were D+/R− status and low renal function. No significant differences in dosing frequency were observed in patients developing neutropenia or not (P = 0.584).

Conclusion

Most patients do not receive the recommended valganciclovir dose. Despite obvious underdosing in a large proportion of patients, effective prophylaxis was maintained and it was not associated as a risk factor for CMV viraemia or leucopenia.