Study of the correlation between two methods used to monitor thymoglobulin therapy in renal transplantation

Polyclonal anti T-lymphocyte antibody therapy monitoring in kidney transplant recipients: comparison of CD3+ T cell and total lymphocyte counts

Objective:

To investigate the correlation between total lymphocyte and CD3⁺ T cell counts in peripheral blood in renal transplant patients treated with anti-thymocyte globulin, and discuss related outcomes.

Methods:

A single-center, retrospective study involving 226 patients submitted to kidney transplant between 2008 and 2013, and treated with anti-thymocyte globulin for induction or treatment of cellular rejection. Doses were adjusted according to CD3⁺ T cell or total lymphocyte counts in peripheral blood.

Results:

A total of 664 paired samples were analyzed. The Spearman's correlation coefficient was 0.416 (p<0.001) for all samples combined; the overall Kappa coefficient was 0.267 (p<0.001). Diagnostic parameters estimated based on total lymphocyte counts were also calculated using the number of CD3⁺ T cells (gold standard), with a cut off of >20 cells/mm³.

Conclusion:

Total lymphocyte and CD3⁺ T cell counts in peripheral blood are not equivalent monitoring strategies in anti-thymocyte globulin therapy.

Role for immune monitoring to tailor induction prophylaxis in pediatric heart recipients

rATG is used for HTx induction but is costly and associated with infection and PTLD.

HYPOTHESIS

Tailoring rATG induction with CD3 monitoring results in less infection, reduced costs, and similar rejection. Retrospective review of HTx recipients receiving rATG induction. Control cases received "usual" rATG dosing (1.5 mg/kg/day typically × 5 days). Starting in October 2009, absolute CD3 monitoring (target <25 cells/mm(3) ) guided rATG dosing (study cases). Outcomes included first-year incidence of infection/rejection, direct costs of therapy, and incidence of PTLD/death. Study cases (n = 32) received fewer doses of rATG (median 4 vs. 5, p < 0.001) and less total rATG (median 3.2 vs. 7.4 mg/kg, p < 0.001) compared with controls (n = 17). There was no difference in incidence of infection, rejection, or patient survival during the first year post-HTx. There was one early death in both groups and one late case of PTLD in the control group. Drug savings were significant (median drug cost per patient $2718 vs. $4756, p < 0.001). CD3-tailored rATG induction in HTx recipients is associated with reduced drug costs and similar rates of rejection/infection. Longer follow-up will determine whether extended benefits are associated with this induction monitoring strategy.

Clinical and Economic Analysis of Delayed Administration of Antithymocyte Globulin for Induction Therapy in Kidney Transplantation

Context

The increasing number of marginal deceased kidney donors and an aging recipient population, prolonged hospitalization, and increased costs have destabilized the economic viability of kidney transplants.

Objective

To determine if a delay in the administration of the day-of-discharge dose of rabbit antithymocyte globulin would result in equivalent clinical outcomes with cost savings.

Design

Single-center, prospective, observational before-and-after study of adult kidney transplant recipients who received induction with rabbit antithymocyte globulin. Intervention—Patients who received a transplant between June 2006 and February 2009 and received rabbit antithymocyte globulin served as the control group. Patients who received a transplant between March 2009 and August 2010 and received rabbit antithymocyte globulin had the day-of-discharge dose delayed to the following day and administered in the clinic. A total of 231 patients (146 in the control group, 85 in the study group) were included. Baseline demographic and clinical characteristics were similar in the 2 groups.

Results

Patients who had delayed administration of rabbit antithymocyte globulin had shorter stays (3.9 vs 3.1 days, P .001) and reduced inpatient costs for rabbit antithymocyte globulin (mean $860/patient); these changes were achieved without affecting acute rejection rates (5% vs 5%, P>> .99) or readmission rates. In conclusion, delayed inpatient administration of rabbit antithymocyte globulin provided identical clinical outcomes while helping to reduce inpatient costs and increase timely discharges.

Pharmacodynamics in the development of new immunosuppressive drugs

Over the past 10-20 years a number of immunosuppressive drugs, such as cyclosporine A, tacrolimus, sirolimus, or mycophenolate mofetil have been approved for clinical use and have been highly successful in preventing or delaying graft rejection. Nevertheless, there is an incessant need for better and safer drugs to improve short-term and long-term outcomes following transplantation. A number of low-molecular-weight molecules that interfere with immune cell functions are in development. These include molecules that inhibit the janus protein tyrosine kinase JAK3, compounds that alter lymphocyte trafficking (the sphingosine-1-phosphate receptor antagonist FTY720), and new malononitrilamides (FK778). All seem to show promising therapeutic potential. Among the biologic agents, there are high expectations for antibodies or recombinant chimeric molecules targeting costimulatory surface molecules or pathways involved in the migration of immune cells. The list of such targets includes the ligand pairs CD28:B7, CD154:CD40, LFA-1:ICAM-1, ICOS:B7RP-1, and VLA-4:VCAM-1. However, the clinical development of drugs for transplantation has proved to be difficult, complex, and time consuming. Therefore, newly emerging drug candidates will also demand better methods for monitoring their efficacy as well as their side effects in vivo. Pharmacokinetics (PK) and pharmacodynamics (PD) are complementary approaches used to select drugs on the basis of their in vivo efficacy as well as safety. Whereas PK monitors the handling of the drug by the body, PD focuses on the biologic effect of the drug on its target. Therefore, PD studies of in vivo efficacy are useful for clinical decisions to determine the optimal dose and type of immunosuppressant. At the preclinical stage, PD is aimed at accelerating the selection of lead compounds via PD-controlled trials in animals. Moreover, PD can help to discover new mechanisms of action for a drug or a drug candidate. However, its full potential has not been used, mainly because of laborious and time-consuming methodology. This review focuses on established and novel PD/PK approaches to assess immunosuppressive compounds in the context of new evolving drugs or drug combinations.