Introduction:
Kidney transplantation is the best available treatment option for patients with end-stage renal disease (ESRD). It surpasses dialysis in terms of survival, patient quality of life and cost-effectiveness. The kidney transplantation program in developing countries is greatly hindered by financial problems, mainly due to costly newer immunosuppressive medications. The Kidney Disease Improving Global Outcomes (KDIGO) clinical practice guidelines suggest using Tacrolimus as the first-line calcineurin inhibitor (CNI) for maintenance therapy of kidney transplant recipients. High cost, chronic nephrotoxicity and other side effects proved significant challenges for the long-term use of these drugs. Ketoconazole, an imidazole antifungal drug, was reported to increase blood levels of Tacrolimus and cyclosporine by inhibiting cytochrome P450 microsomal enzymes in the liver and gut and has financial benefits in combination. A few studies have reported the ketoconazole-cyclosporine combination's short- and long-term safety and financial benefits. Despite the tremendous financial benefits of the ketoconazole-tacrolimus combination, clinical trials studying this combination still need to be made available. Furthermore, long-term follow-up data are not available. In the current study, we analyzed the long-term outcome of patients who received co-administration of Ketoconazole and Tacrolimus in kidney transplant recipients, including the prevalence of biopsy-proven and clinically treated acute rejection rate along with the quality of graft function and patient and kidney graft survival.
Methods:
A retrospective cohort study included all live-related and deceased donor transplant recipients on tacrolimus-based immunosuppression from the pool of kidney transplant patients between 2015 and 2023 in the Department of Nephrology, Christian Medical College, Vellore, Tamil Nadu, India.
Inclusion criteria
Patients who were on tacrolimus-based immunosuppression protocol
Stable graft function with serum creatinine value <2.5 mg/dl.
Study design:
A retrospective cohort study of patients who underwent a primary kidney transplant at our center was conducted, and patients were identified using the transplant center database at the Department of Nephrology, Christian Medical College Vellore, Tamil Nadu, India. Those fulfilling the inclusion criteria were included. Patients were divided into two age-matched groups. Group 1 (Ketoconazole group) patients received Ketoconazole in addition to their Tacrolimus-based triple immunosuppressive treatment, while group 2 served as a control. A combination of Tacrolimus, Mycophenolate Mofetil (MMF) and steroids was maintenance therapy in all patients. Blood pressure, graft function, infections and drug tolerance were assessed retrospectively. Laboratory evaluation included monitoring graft function by serum creatinine, estimated glomerular filtration rate (eGFR), creatinine clearance, urine analysis, and 24-hour urine protein, which was done retrospectively. Other laboratory evaluations considered were haemoglobin and packed cell volume, liver function tests, serum electrolytes, calcium, phosphorous and uric acid, fasting and post-prandial blood sugar, and fasting lipid profile. Tacrolimus whole blood trough level was estimated by liquid chromatography-tandem mass spectrometry (LCMS/MS) and Mycophenolic acid area under curve (MPA-AUC) by high-performance liquid chromatography (HPLC). Cytomegalovirus (CMV) and BK polyomavirus (BK) quantitative PCR was done three months post-transplant and when indicated. A graft biopsy was performed for patients who experienced unexplained graft dysfunction. The graft biopsy was evaluated using the Banff working classification.
Immunosuppressive therapy: High immunological risk patients defined as (KDIGO clinical practice guidelines for the care of kidney transplant recipients) peak panel reactive antibody > 0%, presence of donor-specific antibodies, blood group incompatibility, delayed onset graft function, cold ischemia time > 24 hours and the number of human leukocyte antigen mismatch received Injection Grafalon as induction agent at 9 mg/kg followed by standard triple immunosuppression of Tacrolimus, mycophenolate mofetil (MMF) and prednisolone. Corticosteroid was administered as Methylprednisolone 1 gram intravenously (IV) intraoperatively, followed by Injection Dexamethasone at 0.2 mg/kg on postoperative days 1 and 2. The dose was reduced to 0.1 mg/kg on postoperative days 3 and 4. Oral prednisolone was started at 0.3 mg/kg from postoperative days 5 to 13, followed by 0.2 mg/kg from postoperative days 14 to 20. Postoperative day 21 onwards, oral prednisolone was continued at 0.15 mg/kg. Injection of 20 mg of basiliximab intravenous (IV) over 1 hour was used as an induction agent for low immunologic risk patients. The same dose was repeated on day four post-transplant. Corticosteroid was administered as Methylprednisolone 1 gm IV intraoperatively, followed by Inj. Dexamethasone at 0.2 mg/kg on postoperative days 1 and 2. The dose was reduced to 0.1 mg/kg on postoperative days 3 and 4. Oral prednisolone was started at 0.3 mg/kg from postoperative day 5 to 6 and continued at 5 mg/day after that. Tacrolimus was started at 0.13 mg/kg/day in two doses. Mycophenolate mofetil at 40 mg/kg or Mycophenolate sodium at 30 mg/kg in two divided doses was started irrespective of immunological risk. The target tacrolimus whole blood trough level was 8-11 ng/ml immediately post-transplant, 5-9 ng/ml during the first month to third-month post-transplant and 4-5 ng/ml more than three months post renal transplant. Mycophenolate mofetil (MMF) and Mycophenolic acid area under the curve (MPA-AUC) aimed for 45-60 mg.h/L in the first three months and 30-60 mg.h/L afterwards. The tacrolimus and MMF doses were adjusted according to the drug level. The decision to add Ketoconazole was typically made within the first week of transplant surgery to achieve targeted trough levels before discharge. Ketoconazole was usually started at 100 mg daily and increased to 200 mg daily to maintain the desired trough level.
Infection prophylaxis: All patients received sulfamethoxazole/trimethoprim at the dose of 480 mg once daily for six months post-transplant as prophylaxis for pneumocystis pneumonia and bacterial infections. Cytomegalovirus prophylaxis was given to all transplant patients. The regimen included Tab Valganciclovir 450 mg once daily for six months post-transplant for high immunological risk patients while for three months post-transplant for low immunological risk patients.
Rejection: Acute rejection was presumed when the patient had a sudden increase in serum creatinine that other clinical causes could not explain. Kidney biopsy performed before treatment. The severity of rejection was defined according to Banff criteria. Acute cellular rejection (ACR) was treated initially with IV methylprednisolone for three days. Thymoglobulin was used for steroid-resistant cellular rejection. Acute antibody-mediated rejection (AMR) was treated with a course of 5 to 7 plasmapheresis and replacement intravenous immunoglobulin (IVIG) (150 mg/Kg) in addition to Injection Rituximab at the dose of 1 gm.
Primary Outcomes:
1. Biopsy proven and clinically treated acute rejection rate.
Secondary Outcomes:
1. Quality of graft function
2. Patient and kidney graft survival
3. Incidence of clinically treated infections
Statistical methods: Data from the case report form (CRF) were entered using EPIDATA software and screened for outliers and extreme values using a Box-Cox plot and histogram (for the shape of the distribution). Summary statistics were used to report demographic and clinical characteristics. T-test was used to analyze continuous data with normal distribution, and the Mann-Whitney U test was used for data with non-normal distribution in Groups 1 and 2. A chi-square test was performed for categorical variables with groups. Multivariable logistic regression analysis was done based on the univariate analysis of variable selection used for examining acute rejection risk factors and planned for propensity score analysis. Differences were considered significant at p<0.05. All the statistical analyses were performed using SPSS 25.0.
Results:
Interim analysis was done on 200 patients who underwent kidney transplants at a single centre. Both groups were age-matched and comparable in their baseline characteristics. Ketoconazole was added to Tacrolimus primarily because of inadequate trough level, and initial doses of Tacrolimus were significantly higher in the Ketoconazole group. Ketoconazole augmentation to group 1 resulted in a significant reduction of the Tacrolimus dose that persisted throughout the follow-up period compared to the control group. For each group, Tacrolimus dose at two years and till their last follow-up was lower than that at the commencement of the study. The reduction in Tacrolimus dose was highly significant in the Ketoconazole group. The cumulative dose of Tacrolimus was significantly lower in the Ketoconazole group than in the control group. All patients in the Ketoconazole group showed a reduction in Tacrolimus dose. It remained high or unchanged in some patients in the control group, though the majority showed dose reduction. Dose reduction was insignificant in the control group as compared to the Ketoconazole group. The percentage reduction in Tacrolimus dose was maximal between 3 and 6 months in both groups. Tacrolimus trough level and tacrolimus level fluctuation were comparable in both groups throughout the study. The percentage reduction in Tacrolimus cost was significantly higher in the Ketoconazole group than in the control group. Throughout the study, tolerance to Ketoconazole was good, and there were no side effects associated with Ketoconazole.
Serum creatinine at the start of the study was higher in the Ketoconazole group but comparable with the control group at two years and their last follow-up. Serum Cystatin levels were also comparable in both groups. Estimated glomerular filtration rate (eGFR) showed a declining trend in both groups at two years and at their last follow-up, but it was comparable. The prevalence of proteinuria was comparable in both groups.
Graft biopsies were performed in both groups, given graft dysfunction during follow-up, and the percentage of graft biopsies in both groups was comparable. At least one graft biopsy was performed for each patient. The percentage of graft biopsy was significantly higher in the control group, given clinical suspicion of acute rejection. Evidence of Tacrolimus toxicity was higher in the control group as compared to Ketoconazole group. Chronic Tacrolimus toxicity contributing to chronic allograft nephropathy was evident in both groups and was comparable.
Post-transplant anemia was comparable in both groups. The cause of anemia was nutritional in most patients in both groups. Fasting and post-prandial blood sugar were comparable in both groups. Post-transplant diabetes mellitus was evident within the first three months in both groups, and the percentages in both groups were comparable. Both groups were comparable in new-onset hypertension and the overall prevalence of hypertension. Serum bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein and albumin were comparable in both groups throughout the follow-up period. Elevated transaminases, dyslipidemia and dyselectrolytemia, were comparable in both groups.
Urinary tract infections were comparable in both groups; most were asymptomatic bacteriuria. Other bacterial infections were comparable in both groups, and the most common organ involved was the lung in both groups.
Superficial fungal skin infection was significantly higher in the Ketoconazole group than in the control group. Viral infections, including cytomegalovirus, BK virus and other viral infections, were comparable. SARS-COV2 infection was comparable in both groups.
Complications, including transplant renal artery stenosis, post-transplant erythrocytosis and post-transplant lymphoproliferative disorders, were comparable in both groups.
Bacterial infection with septicemia and septic shock was the most common cause of death in both groups. Chronic antibody-mediated rejection was the leading cause of death censored graft loss in both groups, and the percentages were comparable.
Conclusions:
Ketoconazole augmented Tacrolimus in kidney transplant recipients is associated with significant Tacrolimus dose reduction while maintaining therapeutic immunosuppressive levels and is safe with no side effects. It improves the long-term outcome and does not affect estimated graft and patient survival.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.