Cyclosporine Trough (C0) and 2-Hour Postdose (C2) Levels: Which One Is a Predictor of Graft Loss?

A review of landmark studies on maintenance immunosuppressive regimens in kidney transplantation

Immunosuppressive medications play a pivotal role in kidney transplantation, and the calcineurin inhibitors (CNIs), including cyclosporine A (CsA) and tacrolimus (TAC), are considered as the backbone of maintenance immunosuppressive regimens. Since the introduction of CNIs in kidney transplantation, the incidence of acute rejection has decreased, and allograft survival has improved significantly. However, CNI nephrotoxicity has been a major concern, believed to heavily impact long-term allograft survival and function. To address this concern, several CNI-sparing regimens were developed and studied in randomized, controlled, clinical trials, aiming to reduce CNI exposure and preserve long-term allograft function. However, more recent information has revealed that CNI nephrotoxicity is not the primary cause of late allograft failure, and its histopathology is neither specific nor pathognomonic. In this review, we discuss the historical development of maintenance immunosuppressive regimens in kidney transplantation, covering the early era of transplantation, the CNI-sparing era, and the current era where the alloimmune response, rather than CNI nephrotoxicity, appears to be the major contributor to late allograft failure. Our goal is to provide a chronological overview of the development of maintenance immunosuppressive regimens and summarize the most recent information for clinicians caring for kidney transplant recipients (KTRs).

Immunosuppression Monitoring-What Clinician Needs to Know?

The liver is well known for its immunotolerance, but rejection without immunosuppression is frequently encountered post liver transplantation, especially in humans.1 Indeed, the amount of immunosuppression required post liver transplant is less compared to other organ transplants like kidney, heart, and intestine.2 Reports of successful weaning of immunosuppression have been reported but are not practiced for fear of unwanted alloimmune response leading to rejection. Life-long immunosuppression is needed in most patients for graft survival but is associated with side effects like renal dysfunction, metabolic abnormalities, or risk of de novo malignancies. Also, the appropriate dose of immunosuppression to achieve adequate graft function and prevention of toxicities is very important. One shoe does not fit all. There are significant individual variations in response and side effect profile. Also, the level of immunosuppression varies with the underlying liver disease like autoimmune disease requires higher immunosuppression. Thus, monitoring the adequate immunosuppression with the minimization of drug toxicity is imperative post-transplant. Unfortunately, the current methods for immunosuppression monitoring rely on testing the immunosuppressive drug levels rather than the immune system activity. We have discussed the concept of alloreactivity, available methods of immunosuppression and drug monitoring and investigational methods in this review.

Association Between Blood and Lymphocyte Levels of Cyclosporin A and Infectious Complications in Renal Transplant Patients

Objectives

This study aims to investigate a potential association between whole blood and lymphocyte Cyclosporin A (CyA) levels and the occurrence and frequency of infectious complications in kidney transplant patients.

Methods

The study involves 130 kidney transplant recipients who received CyA in addition to Mycophenolate Mofetil and steroids. CyA whole blood trough and maximum level (CyA BL₀ and CyA BLm) as well as the corresponding levels in the lymphocytes (CyA L₀ and CyA Lm) were measured for 6 months post-transplantation.

Results

Cytomegalovirus (CMV) as well as urinary tract infections (UTIs) were the most commonly diagnosed with an incidence of 24.6% and 26.2%, respectively. Only CyA L₀ showed a significant association with CMV infection occurrence (adjusted OR = 1.051, 95% CI .997–1.025, P-value 0.046). A positive linear correlation was found between CyA BL₀, CyA BLm and CyA Lm and the number of CMV episodes per patient.

Conclusion

We showed an association between the CMV infections occurrence and the trough lymphocyte level of CyA (CyA L₀). Both lymphocyte CyA levels also correlated with the frequency of CMV infections. Further studies are needed to establish the optimal range of both CyA blood and lymphocyte levels and decrease the risk of opportunistic infections in high risk patients.

Optical sensing in POCT: the contribution of the Institute of Applied Physics of the Italian CNR

The activity developed at the Institute of Applied Physics “Nello Carrara” in strict collaboration with physicians is described with particular attention to the measurement of bile-containing refluxes in the gastroesophageal apparatus, to the detection of gastric carbon dioxide in intensive care patients, to the measurement of sepsis biomarkers in serum samples and to the measurements of immunosuppressants in transplanted patients.

Lipid parameters, doses and blood levels of calcineurin inhibitors in renal transplant patients

The calcineurin inhibitors (CNIs) [cyclosporin A (CsA) and tacrolimus (Tac)] are currently the most widely prescribed drugs for maintenance of immunosuppression after renal transplantation. These immunosuppressants are associated with side effects such as hyperlipidemia. We evaluated the differential effects of different CNIs on serum lipid parameters in renal transplant patients. Moreover, the aim of this study is to investigate the relationships between doses and blood levels of CNIs, and blood levels of CNIs and lipid parameters retrospectively. Two groups of 98 non-diabetic renal transplant patients, each treated with different CNIs, were studied: group A (n = 50, mean age: 31 ± 10 years), CsA, mycophenolate mofetil/azathioprin, steroid; group B (I = 48, mean age: 34 ± 12 years), Tac, mycophenolate mofetil/azathioprin, steroid. In renal transplant patients, CNIs blood levels and doses were examined at 1, 3, 6, 9, and 12 months after transplantation. Biochemical laboratory parameters including plasma lipids [total-cholesterol (CHOL), low-density lipoprotein (LDL)-CHOL, high-density lipoprotein (HDL)-CHOL, and triglycerides (TG)], CNI levels and doses were examined at 1, 3, 6, 9, and 12 months after transplantation. None of the patients received anti-lipidemic drugs during the study period. Blood levels of CNIs were detectable in all whole-blood samples by Cloned- Enzyme-Donor Immunoassay (CEDIA). The relationship between CNIs blood levels and CHOL, (LDL)-CHOL, HDL-CHOL, TG were evaluated. The mean serum CHOL levels and LDL-CHOL levels of patients in group A were found significantly higher than the patients in group B during the 12 month of follow up (p < 0.05). There was no significant difference in TG and HDL-CHOL plasma levels between group A and group B (p > 0.005). In group A the daily dose of CsA was significantly correlated with the mean blood levels of CsA at the 1st and 3rd months (r = 0.387, p = 0.005; r = 0.386, p = 0.006), respectively. In group A, the daily dose of CsA was significantly correlated with the mean serum TG levels during the 12 month of follow up (r = 0.420, p = 0.003). In group B, the daily dose of Tac was significantly correlated with the mean blood level of Tac (r = 0.335, p = 0.020) at the 1st month. No correlation was found between mean Tac blood levels and lipid parameters during the 12-month of follow up (p > 0.05). Significant positive correlation was observed between the CsA blood levels and LDL-CHOL levels (r = 0.338, p = 0.027) at the 3rd month. In the renal transplant patients with well functioning grafts, CsA therapy is associated with increased CHOL and LDL-CHOL ratio which represents an increased atherogenic risk tended to be associated with CsA. Serum LDL-CHOL levels may be effected by blood CsA levels.

Is the lower cyclosporine concentration at 2 hours after dosing safe in kidney transplant recipients?

OBJECTIVE

To determine the correlation between cyclosporine blood concentration at 2 hours after dosing (C2) and renal allograft function.

MATERIALS AND METHODS

From 2008 to 2010, 1191 kidney transplant recipients (718 male and 473 female patients) were studied. The correlation between serum creatinine concentration and C2 blood concentration was stratified as 400, 600, 800, and 1000 ng/mL.

RESULTS

The mean (SD) C2 was 620 (235) ng/mL, and serum creatinine concentration was 1.49 (0.68) mg/dL. At multivariate regression analysis, no significant correlation was observed between serum creatinine concentration and C2 blood concentrations of 600, 800, or 1000 ng/mL (P=.18, .57, and .76, respectively); however, it was associated at 400 ng/mL (P=.03). Moreover, 36.1% of 3159 samples demonstrated satisfactory renal allograft function despite low C2 blood concentration between 400 and 600 ng/mL.

CONCLUSION

During maintenance therapy, C2 blood concentration between 400 and 600 ng/mL is effective and safe for providing prophylaxis against rejection, and can improve long-term survival by decreasing cyclosporine toxicity.