C2 monitoring in maintenance renal transplant recipients: is it worthwhile?

Presently, there is little knowledge regarding cyclosporine (CsA) concentration at 2 hr post-dose (C2) monitoring in maintenance patients. This study evaluates the actual C2 range in stable renal transplant recipients (who underwent transplantation >12 months ago). In addition, we investigated whether underexposure or overexposure to CsA (assessed by C2) affects graft function (as measured by serum [S]-creatinine). All renal transplant recipients in Norway receiving CsA were asked to participate; 1447 fulfilled the criteria. Valid C2 and CsA trough concentration (C0) measurements were performed in 1032 renal transplant recipients (71%) monitored by C0. Target C0 level was 75 to 125 mumol/L. CsA levels were measured using a Cloned Enzyme Donor Immunoassay method, and all analyses were performed in the same laboratory (overall mean [+/-standard deviation] CsA C0=112+/-31 mug/L, CsA C2=697+/-211 mug/L [range 81-1580 mug/L], CsA dose [mg/day]=208+/-61, CsA dose [mg/kg/day]=2.8+/-1.1, and S-creatinine=141+/-58 mumol/L). A univariate analysis of variance showed that patients with C2 levels between 700 and 800 mug/L (n=203, S-creatinine=136+/-49 mumol/L) had significantly lower S-creatinine levels compared with patients with C2 levels greater than 950 mug/L (n=94, S-creatinine=152+/-56 mumol/L) (P<0.02). The same was true for patients with C2 levels less than 450 mug/L (n=95, S-creatinine 141+/-72 mumol/L) (P<0.05) when compared with patients with C2 levels greater than 950 mug/L. There was no significant difference in S-creatinine between patients in the low and intermediate C2 group; 666 patients had C0 levels in the therapeutic range (75-125 mumol/L). A linear regression showed a significant relation between S-creatinine and C2 for these patients (P=0.03). The corresponding relation between S-creatinine and C0 was nonsignificant (P=0.3). Monitoring of C2 in maintenance patients is a valuable tool to detect overexposure to CsA. Until results from prospective studies are available, we recommend C0 in the therapeutic range and reduction in CsA in overexposed patients, aiming at a C2 value between 700 and 800 mug/L.

Individualized T cell monitored administration of ATG versus OKT3 in steroid-resistant kidney graft rejection.

Acute steroid-resistant rejection episodes are recommended to be treated with set doses of anti-thymocyte globulin (ATG) or anti-CD3 monoclonal antibody (OKT3). Individualized T cell monitoring has been proposed as a tool for dose finding. A randomized study comparing the efficacy and safety of ATG (n = 27) with OKT3 (n = 28) in the treatment of biopsy verified acute steroid-resistant rejection (ASRR) when both drugs were administered on the basis of daily individualized T cell measurements. A drop to below 50 cells/mm3 CD2+ T cells was considered adequate and used to guide the dose of ATG/OKT3. Demographic, clinical and histopathological severities of rejections were equal in the two groups. During the 10 days of T cell monitoring and antibody treatment, 13 patients were in need of dialysis (ATG = 7/OKT3 = 6). Two grafts did not respond to antibody treatment and were lost due to rejection (ATG = 1/OKT3 = 1). There were 26 biopsy verified re-rejections (ATG = 12/OKT3 = 14) within the first 3 months following antibody treatment. Mean serum creatinine (micromol/L) was similar in the two groups (ATG/OKT3: before rejection 157 +/- 72/151 +/- 88, at start of antibody treatment 308 +/- 125/330 +/- 94, end of antibody treatment 254 +/- 122/246 +/- 144 and at follow-up after a mean of 32 months 166 +/- 55 (n = 24)/164 +/- 57(n = 23)). To keep the T cell count below 50 cells/mm3, average dose ATG given was 354 +/- 151 mg (2.3 administrations, range 1-4) and average OKT3 was 32.5 +/- 6.8 mg in 10 doses. In conclusion, individualized T cell monitored administration of ATG and OKT3 is safe and seems as effective as a standard set dose in treatment of ASRR. Tailoring the dose for each individual patient lowers the cost.