Maribavir: Mechanism of action, clinical, and translational science.

Maribavir is an oral benzimidazole riboside for treatment of post-transplant cytomegalovirus (CMV) infection/disease that is refractory to prior antiviral treatment (with or without resistance). Through competitive inhibition of adenosine triphosphate, maribavir prevents the phosphorylation actions of UL97 to inhibit CMV DNA replication, encapsidation, and nuclear egress. Maribavir is active against CMV strains with viral DNA polymerase mutations that confer resistance to other CMV antivirals. After oral administration, maribavir is rapidly and highly absorbed (fraction absorbed >90%). The approved dose of 400 mg twice daily (b.i.d.) achieves a steady-state area under the curve per dosing interval of 128 h*µg/mL and trough concentration of 4.90 µg/mL (13.0 µM). Maribavir is highly bound to human plasma proteins (98%) with a small apparent volume of distribution of 27.3 L. Maribavir is primarily cleared by hepatic CYP3A4 metabolism; its major metabolite, VP44669 (pharmacologically inactive), is excreted in the urine and feces. There is no clinically relevant impact on maribavir pharmacokinetics by age, sex, race/ethnicity, body weight, transplant type, or hepatic/renal impairment status. In phase II dose-ranging studies, maribavir showed similar rates of CMV viral clearance across 400, 800, or 1200 mg b.i.d. groups, ranging from 62.5-70% in study 202 (NCT01611974) and 74-83% in study 203 (EudraCT 2010-024247-32). In the phase III SOLSTICE trial (NCT02931539), maribavir 400 mg b.i.d. demonstrated superior CMV viremia clearance at week 8 versus investigator-assigned treatments, with lower treatment discontinuation rates. Dysgeusia, nausea, vomiting, and diarrhea were commonly experienced adverse events among patients treated with maribavir in clinical trials.

Retrospective chart review of transplant recipients with cytomegalovirus infection who received maribavir in the Phase 3 SOLSTICE trial: Data at 52 weeks post-maribavir treatment initiation.

BACKGROUND: Cytomegalovirus (CMV) infection is a frequent complication in haematopoietic cell/solid organ transplant (HCT/SOT) recipients. Previous studies report all-cause mortality rates of 31% and 50% in HCT/SOT recipients post-treatment initiation with conventional anti-CMV therapies for refractory or resistant CMV. METHODS: This was a multi-country, retrospective medical chart review study of HCT/SOT recipients with refractory CMV infection with or without resistance (R/R) who were randomized to the maribavir arm in the open-label Phase 3 SOLSTICE trial. Patients came from 21 SOLSTICE sites across 6 countries; each site randomized ≥3 patients to the maribavir arm. Patients were followed for 52 weeks (SOLSTICE trial period: 20 weeks; follow-up chart review period: 32 weeks). The primary outcomes were mortality and graft status. RESULTS: Of 234 patients who were randomized and received maribavir in SOLSTICE, chart abstraction was completed for all 109 patients enrolled across 21 trial sites (SOT, 68/142; HCT, 41/92). At 52 weeks, overall mortality was 15.6% (17/109) and survival probability was 0.84. Among SOT recipients, survival probability was 0.96, and 3 (4.4%) deaths occurred during the chart review period. For the HCT recipients, survival probability was 0.65 with 14 (34.1%) deaths; 8 occurred during SOLSTICE and 6 during the chart review period. No new graft loss or re-transplantation occurred during the chart review period. CONCLUSIONS: Overall mortality at 52 weeks post-maribavir treatment initiation in this sub-cohort of patients from the SOLSTICE trial was lower than that previously reported for similar populations treated with conventional therapies for R/R cytomegalovirus infection.

Maribavir for Refractory Cytomegalovirus Infections With or Without Resistance Post-Transplant: Results From a Phase 3 Randomized Clinical Trial.

BACKGROUND: Therapies for refractory cytomegalovirus infections (with or without resistance [R/R]) in transplant recipients are limited by toxicities. Maribavir has multimodal anti-cytomegalovirus activity through the inhibition of UL97 protein kinase. METHODS: In this phase 3, open-label study, hematopoietic-cell and solid-organ transplant recipients with R/R cytomegalovirus were randomized 2:1 to maribavir 400 mg twice daily or investigator-assigned therapy (IAT; valganciclovir/ganciclovir, foscarnet, or cidofovir) for 8 weeks, with 12 weeks of follow-up. The primary endpoint was confirmed cytomegalovirus clearance at end of week 8. The key secondary endpoint was achievement of cytomegalovirus clearance and symptom control at end of week 8, maintained through week 16. RESULTS: 352 patients were randomized (235 maribavir; 117 IAT). Significantly more patients in the maribavir versus IAT group achieved the primary endpoint (55.7% vs 23.9%; adjusted difference [95% confidence interval (CI)]: 32.8% [22.80-42.74]; P < .001) and key secondary endpoint (18.7% vs 10.3%; adjusted difference [95% CI]: 9.5% [2.02-16.88]; P = .01). Rates of treatment-emergent adverse events (TEAEs) were similar between groups (maribavir, 97.4%; IAT, 91.4%). Maribavir was associated with less acute kidney injury versus foscarnet (8.5% vs 21.3%) and neutropenia versus valganciclovir/ganciclovir (9.4% vs 33.9%). Fewer patients discontinued treatment due to TEAEs with maribavir (13.2%) than IAT (31.9%). One patient per group had fatal treatment-related TEAEs. CONCLUSIONS: Maribavir was superior to IAT for cytomegalovirus viremia clearance and viremia clearance plus symptom control maintained post-therapy in transplant recipients with R/R cytomegalovirus. Maribavir had fewer treatment discontinuations due to TEAEs than IAT. Clinical Trials Registration. NCT02931539 (SOLSTICE).

Mycophenolate mofetil versus enteric-coated mycophenolate sodium: a large, single-center comparison of dose adjustments and outcomes in kidney transplant recipients.

BACKGROUND: Although enteric-coated mycophenolate sodium (EC-MPS) was developed to reduce gastrointestinal (GI) side effects in kidney transplantation, a multicenter clinical trial of patients undergoing de novo renal transplantation found that efficacy failure and adverse GI event rates for EC-MPS were comparable with mycophenolate mofetil (MMF). A common strategy to mitigate mycophenolic acid-related GI adverse events includes dose manipulations such as split dosing, dose reduction, and discontinuation. Several studies have demonstrated that dose alterations with MMF are associated with poorer graft outcomes. METHODS: To determine whether there was a clinically significant difference in dose alterations and outcomes with EC-MPS compared with MMF, we conducted a retrospective study comparing MMF and EC-MPS in all consecutive kidney transplants (n=1709) between 2000 and 2006. RESULTS: Graft survival between MMF and EC-MPS patients was not different during the study period (P=0.9928). The incidence of biopsy-proven acute rejection at 2 years was higher in the MMF group (30.2% MMF vs. 21.9% EC-MPS, P=0.0004). The adjusted risk of dose reductions was significantly higher in MMF-treated patients (hazard ratio=1.703, P<0.0001). Similarly, the adjusted risk of drug discontinuation was higher in the MMF group (hazard ratio=1.507, P=0.0002). EC-MPS patients also demonstrated a trend toward a lower incidence of infections and a significantly lower incidence of fungal infections. CONCLUSION: EC-MPS was associated with fewer dose reductions or discontinuations, which may have translated into the observed significantly lower incidence of biopsy-proven rejection. EC-MPS has become the mycophenolic acid agent of choice at this large center.

Dual kidney transplantation: a case-control comparison with single kidney transplantation from standard and expanded criteria donors.

BACKGROUND: The purpose of this study was to perform a case-matched cohort analysis of dual kidney transplantation (DKT) from expanded criteria donors (ECDs) compared to single kidney transplantation (SKT) from concurrent ECDs and standard criteria donors (SCDs, defined as non-ECD). METHODS: Deceased donor (DD) kidney transplants (KTs) performed at a single center between October 2001 and February 2006 were reviewed retrospectively. If the calculated DD creatinine clearance (CrCl) was <65 mL/min, then the kidneys were transplanted dually into a single patient. In the case of DKT and SKT from ECDs, low risk patients were chosen and informed consent was obtained. Patients in each group were matched for age, gender, race, transplant number, and time of transplant. RESULTS: Of 294 adult DD KTs performed, 16 (5%) were DKTs, which were matched with 16 concurrent SCD and 16 ECD SKT patients. Mean donor age in years (65 DKT vs. 33 SCD vs. 61 ECD; P<0.0001) and mean donor CrCl in ml/min (54 DKT vs. 91 SCD vs. 76 ECD; P=0.002) were different between groups. Patient survival was 100% in the DKT and SCD SKT groups and 94% in the ECD SKT group (mean follow up 23-28 months); graft survival rates in the DKT, SCD, and ECD groups were 81%, 81%, and 94%, respectively (P=NS). Graft function, rejection, and morbidity were similar between groups. CONCLUSIONS: DKT using kidneys from marginal ECDs is a viable option to counteract the growing shortage of available organs. Excellent short-term results and renal function can be achieved with older, low nephron mass donors provided that both kidneys are transplanted into a single recipient.

Experience with dual kidney transplants from donors at the extremes of age.

BACKGROUND: Dual kidney transplantation (DKT) from donors at the extremes of age represents one approach to expanding the organ donor pool. The purpose of this study was to review our experience with DKT from older donors and en bloc KT (EBKT) from small pediatric donors. METHODS: Deceased donor KTs performed at our center between October 2001 and November 2005, were reviewed retrospectively. If the calculated creatinine clearance in an expanded criteria donor was <65 mL/min, then the kidneys were transplanted dually into a single adult recipient. If a pediatric donor weighed <15 kg, then the kidneys were transplanted en bloc. In both instances, low-risk recipients were chosen (primary transplant, low sensitization, body mass index <25 kg/m(2), human leukocyte antigen matching). Donor, recipient, and transplant characteristics, waiting time, and outcomes were examined. RESULTS: Of a total of 279 deceased donor KTs during the 49-month study period, 15 (5%) recipients underwent DKT and 5 (2%) underwent EBKT. Mean donor age was 65.4 years and 21.4 months in the DKT and EBKT groups, respectively. Patient survival rates in both groups were 100% with a mean follow-up of 22 months (minimum, 6 months). Kidney graft survival rates were 80% (12/15) and 60% (3/5) in the DKT and EBKT groups, respectively. The combined incidence of delayed graft function was 10%. Mean 12-month glomerular filtration rates were 46 mL/min and 66 mL/min in the DKT and EBKT groups, respectively. CONCLUSIONS: DKT using kidneys from marginal elderly donors and EBKT from small pediatric donors appear to offer a viable option to counteract the shortage of acceptable kidney donors.

Intermediate-term outcomes with expanded criteria deceased donors in kidney transplantation: a spectrum or specter of quality?

OBJECTIVE: To compare intermediate-term outcomes in adult recipients of expanded criteria (ECD) versus concurrent standard criteria (SCD) deceased donor kidney transplants at a single center using a standardized approach. SUMMARY BACKGROUND DATA: Expanded criteria donors (ECDs) are a source of kidneys that increase the donor organ pool, but the value of transplanting these kidneys has been questioned because of concerns regarding diminished survival and predicted poorer intermediate-term outcomes. METHODS: Over a 47-month period, we performed 244 deceased donor kidney transplants into adult recipients, including 143 from SCDs and 101 from ECDs. Management algorithms were implemented to preserve nephron function, and recipient selection for an ECD kidney transplant was based on low immunologic risk. All patients received depleting antibody induction in combination with tacrolimus and mycophenolate mofetil. A total of 188 patients (77%) had at least a 1-year follow-up. RESULTS: ECDs were older, had a higher BMI, had an increased incidence of cerebrovascular brain death and preexisting donor hypertension, and had a lower estimated creatinine clearance (CrCl, all P < 0.01) compared with SCDs. Cold ischemic times were similar between groups, but more ECD kidneys were preserved with pulsatile perfusion (P < 0.01). ECD kidney recipients were older, less sensitized, had a lower BMI, had fewer 0-antigen mismatches, and had a shorter waiting time (all P < 0.01) compared with SCD kidney recipients. Actual patient (93%) and kidney graft (83%) survival rates were similar between groups with a mean follow-up of 24 months. The rates of delayed graft function (DGF), acute rejection, readmissions, operative complications, major infections, and resource utilization were comparable between groups. Renal function followed longitudinally was consistently better in SCD patients (P < 0.05). Black recipients had higher rates of DGF, acute rejection, and graft loss (P < 0.05), but the effects were less pronounced in the ECD group. CONCLUSIONS: By appropriate donor and recipient profiling and the use of management algorithms to project and protect renal function, excellent intermediate-term outcomes can be achieved with ECD kidney transplants that are comparable to SCD kidney transplants.

Optimal use of older donors and recipients in kidney transplantation.

BACKGROUND: The aging donor and recipient population have led to new challenges in kidney transplantation. The purpose of this study was to review retrospectively our single center experience in deceased-donor kidney transplantation, with respect to donor and recipient age. METHODS: From October 1, 2001, through February 20, 2004, we performed 144 deceased-donor kidney transplantations, which included 37 procedures (26%) in recipients > or =60 years old and 107 procedures (74%) in recipients 19 to 59 years old. The deceased-donor pool included 57 expanded criteria donors (ECD) and 87 standard criteria donors (defined as not ECD). ECD kidneys were used by matching estimated renal functional mass to recipient size (body mass index, <25 kg/m(2)), which included the use of dual kidney transplantations (n = 9). ECD kidney recipients were further selected on the basis of age >40 years and low immunologic risk. Recipients received rabbit antithymocyte globulin or alemtuzumab induction in combination with tacrolimus, mycophenolate mofetil, and steroids. RESULTS: The mean age differed between recipient groups (65 vs 46 years; P < .001). In recipients > or =60 years old, 23 recipients (62%) received kidney transplants from ECDs compared with 34 kidney transplants from ECDs (32%; P < .001) in recipients who were <60 years old. Patient survival was 89% in recipients who were > or =60 years old, compared with 95% in recipients who were <60 years old (P = .11), with a mean follow-up time of 27 months. Kidney graft survival rates were 84% in both recipient groups. Initial and subsequent graft function, rejection, infection, reoperation, length of stay, readmission, and resource use were similar among groups. CONCLUSION: By the matching of nephron mass with recipient size and avoiding the use of ECD kidneys in recipients with a high immunologic risk, short-term outcomes that are comparable with standard criteria donor kidneys in younger patients can be achieved with either older donors or recipients, regardless of age.

Conversion to sirolimus-based maintenance immunosuppression using daclizumab bridge therapy in renal transplant recipients.

INTRODUCTION: Conversion from calcineurin inhibitor (CI)-based maintenance immunosuppression to sirolimus (SRL)-based immunosuppression may be beneficial in selected renal transplant recipients. The purpose of this study was to evaluate the safety and efficacy of a daclizumab (DAC) bridge protocol in patients converted from CI- to SRL-based maintenance immunosuppression. METHODS: We conducted a retrospective chart review of renal transplant recipients who were converted to SRL at least 2 months post-transplant. The protocol consisted of an abrupt discontinuation of either cyclosporin (CsA) or tacrolimus (TAC), initiation of SRL within 48 h of CI discontinuation, and DAC 2 mg/kg at the time of CI discontinuation and again at 14 d (depending on the SRL serum concentration). The SRL starting dose was based on risk stratification in each patient. RESULTS: Twenty-one renal transplant patients were converted to SRL (11 from TAC, 10 from CsA) between October 2001 and July 2003. Conversion occurred at a mean of 23 months post-transplant. Indications for SRL conversion included 12 for chronic allograft nephropathy (CAN), four for CI-associated neurotoxicity, two for thrombotic microangiopathy (TMA), two for post-transplant diabetes mellitus (PTDM), and one for polyomavirus interstitial nephritis (PVN). Mean follow-up was 16 months from time of conversion. Therapeutic SRL levels were reached at a mean of 14 d. Total serum cholesterol levels increased from a mean of 205 (+/- 47) to 234 (+/- 55) mg/dL (P = 0.014), and serum triglyceride levels increased from a mean of 186 (+/- 66) to 257 (+/- 88) mg/dL (P = 0.002). In addition, mean haemoglobin level decreased from 12.0 (+/- 2.3) to 10.5 (+/- 2.1) g/dL (P = 0.002); total white blood cell count decreased from 8300 (+/- 4300) to 4700 (+/- 1400)/mm(3) (P < 0.001); and platelet count decreased from 238 000 (+/- 72 800) to 186 000 (+/- 51 900)/mm(3) (P = 0.002) from before to after conversion. Patients experienced the following side-effects while taking SRL: diarrhoea (n = 6), peripheral oedema (n = 5), arthralgias (n = 4), anaemia (n = 4), oral ulcers (n = 1), deep vein thrombosis (n = 1), shortness of breath (n = 1), and mild increase in serum transaminases (n = 1). Two patients (9.5%) discontinued SRL due to side-effects, both secondary to severe arthralgias. There were two serious infections noted after conversion: one Pseudomonas aeruginosa urosepsis, and one PVN (that was ongoing prior to conversion). Patient survival was 100%, and kidney graft survival was 76%. Five patients (24%) lost their allograft after conversion due to progression of CAN (n = 2), persistent TMA in the kidney (n = 1), patient self-discontinuation of sirolimus (n = 1), and preexisting PVN unresponsive to cidofovir therapy (n = 1). Of the five patients who lost their allograft, the mean serum creatinine at the time of conversion was 3.5 (+/-1.1) mg/dL compared with 2.2 (+/- 0.8) mg/dL in patients who did not lose their allograft (P = 0.034). No acute rejection episodes occurred after conversion to sirolimus. CONCLUSIONS: DAC bridge therapy provides safe and effective immunosuppressive coverage while converting renal transplant recipients from CI- to SRL-based maintenance immunosuppressive therapy. A pharmacoeconomic analysis, however, is necessary to determine the cost-effectiveness of this conversion protocol.

Increased kidney transplantation utilizing expanded criteria deceased organ donors with results comparable to standard criteria donor transplant.

OBJECTIVE: To compare outcomes in recipients of expanded criteria donor (ECD) versus standard criteria donor (SCD) kidneys at a single center using a standardized approach with similar immunosuppression. SUMMARY BACKGROUND DATA: Expanded criteria deceased organ donors (ECD) are a source of kidneys that permit more patients to benefit from transplantation. ECD is defined as all deceased donors older than 60 years and donors older than 50 years with 2 of the following: hypertension, stroke as the cause of death, or pre-retrieval serum creatinine (SCr) greater than 1.5 mg/dl. METHODS: We retrospectively studied 90 recipients of adult deceased donor kidneys transplanted from October 1, 2001 to February 17, 2003, including 37 (41%) from ECDs and 53 (59%) from SCDs. ECD kidneys were used by matching estimated renal functional mass to recipient need, including the use of dual kidney transplants (n = 7). ECD kidney recipients were further selected on the basis of older age, HLA-matching, low allosensitization, and low body mass index. All patients received a similar immunosuppressive regimen. Minimum follow up was 9 months. RESULTS: There were significant differences in donor and recipient characteristics between ECD and SCD transplants. Patient (99%) and kidney graft survival (88%) rates and morbidity were similar between the 2 groups, with a mean follow-up of 16 months. Initial graft function and the mean 1-week and 1-, 3-, 6-, 12-, and 18-month SCr levels were similar among groups. CONCLUSIONS: The use of ECD kidneys at our center effectively doubled our transplant volume within 1 year. A systematic approach to ECD kidneys based on nephron mass matching and nephron sparing measures may provide optimal utilization with short-term outcomes and renal function comparable to SCD kidneys.

Kidney and pancreas transplantation at Wake Forest University Baptist Medical Center.

More than 1,100 transplants have been performed at WFUBMC, including 60 pediatric transplants and 40 pancreas transplants. The one-year living donor kidney graft survival rate exceeds 90% and the 2 year deceased donor kidney graft survival rate exceeds 80%. The current active waiting list includes more than 300 candidates. Despite more transplants being performed, we continue to under-serve our referral area, which has among the highest rates of hypertension, diabetes, and end stage renal disease in the country. The AOTP has experienced a period of rapid growth over the past 2 years based upon sharing of zero HLA antigen-mismatched kidneys, use of ECD kidneys, liberalization of donor and recipient selection criteria, and the continued development of the pancreas transplant and laparoscopic donor nephrectomy programs. The pancreas transplant program will continue to grow as the waiting list enlarges and matures, with a 200% increase in activity expected within the next few years. The LDKT program will expand as more emphasis is placed on our pretransplant practice, including the more liberal application of laparoscopic donor nephrectomy, which has now become a standard procedure at our WFUBMC is involved in a number of clinical research projects studying new immunosuppressive agents and regimens. In this chapter, we have presented our recent experience with KTX in the elderly, ECD kidneys, alternate day Thymoglobulin administration, valganciclovir prophylaxis, SRL conversion using daclizumab bridge therapy, and pancreas transplantation with portal-enteric drainage. We plan to initiate a number of new protocols in the immediate future, including desensitization of the highly sensitized patient, ABO incompatible transplantation, transplantation of the HIV-positive patient, steroid withdrawal and avoidance regimens, living kidney donation from the anonymous altruistic donor, paired kidney exchanges from living donors, and islet transplantation. WFUBMC remains the most active donor hospital in North Carolina, and a non-heart beating donor protocol has been successfully initiated at our facility. Although much has been accomplished, a number of challenges remain. We look forward to building on our accomplishments, confronting the challenges, and achieving a level of excellence that could only be attained by mutual commitment from a dedicated, multidisciplinary team.