Tacrolimus Pharmacodynamics and Pharmacogenetics along the Calcineurin Pathway in Human Lymphocytes

Abstract

BACKGROUND Although therapeutic drug monitoring has improved the clinical use of immunosuppressive drugs, there is still interpatient variability in efficacy and toxicity that pharmacodynamic monitoring may help to reduce. To select the best biomarkers of tacrolimus pharmacodynamics, we explored the strength and variability of signal transduction and the influence of polymorphisms along the calcineurin pathway. METHODS Peripheral blood mononuclear cells from 35 healthy volunteers were incubated with tacrolimus (0.1–50 ng/mL) and stimulated ex vivo. Inhibition of NFAT1 (nuclear factor of activated T cells 1) translocation to the nucleus and intracellular expression of interleukin-2 in CD4+ and CD8+ T cells and the surface activation marker CD25 in CD3+ cells were measured by flow cytometry. We sequenced the promoter regions of immunophilins and calcineurin subunits and characterized selected single nucleotide polymorphisms in the genes of the calcineurin pathway with allelic discrimination assays. RESULTS All responses closely fitted an I/Imax sigmoid model. Large interindividual variability (n = 30) in I0 and IC50 was found for all biomarkers. Moreover, strong and statistically significant associations were found between tacrolimus pharmacodynamic parameters and polymorphisms in the genes coding cyclophilin A, the calcineurin catalytic subunit α isoenzyme, and CD25. CONCLUSIONS This study demonstrates the consistency and large interindividual variability of signal transduction along the calcineurin pathway, as well as the strong influence of pharmacogenetic polymorphisms in the calcineurin cascade on both the physiological activity of this route and tacrolimus pharmacodynamics.

Pharmacogenetic—Whole blood and intracellular pharmacokinetic—Pharmacodynamic (PG-PK2-PD) relationship of tacrolimus in liver transplant recipients

“…Moreover, another determinant of the complex relationship between CaN activity and exposure to TAC could be SNPs in the promoter region of the catalytic subunit of CaN (e.g. PPP3CA, rs45441997), as highlighted by the work of Noceti et al [41]. Unfortunately, genetic analysis of gene involved in the pharmacodynamic pathway of TAC could not be performed in our work.…”

Exploring genetic and non‐genetic risk factors for delayed graft function, acute and subclinical rejection in renal transplant recipients

“…However, no pharmacogenetic risk factors for subclinical rejection have been reported for renal transplant recipients on CsA therapy. Genetic variability in genes coding for calcineurin could alter the susceptibility for CsA as has been shown previously for tacrolimus . Polymorphisms in these genes could potentially be related to acute rejection and/or subclinical rejection .…”

Association of the <em>PPP3CA</em> c.249G&gt;A variant with clinical outcomes of tacrolimus-based therapy in kidney transplant recipients

“…Biomarkers may be useful as they can quantitatively reflect the effects of a given drug on its target and also predict the clinical response to a drug 25. As the quantity of genetic data grows, genotyping will increasingly yield these useful biomarkers 26…”

“…Noceti et al25 suggested a strong association between TAC pharmacodynamic parameters and polymorphisms in PPP3CA . The authors reported that, in ex vivo TAC-treated peripheral blood mononuclear cells from 35 volunteers, the PPP3CA rs45441997 variant was associated with variability in intracellular IL-2 expression in CD4 + T cells 25.…”

“…The authors reported that, in ex vivo TAC-treated peripheral blood mononuclear cells from 35 volunteers, the PPP3CA rs45441997 variant was associated with variability in intracellular IL-2 expression in CD4 + T cells 25. IL-2, discovered as a T cell growth factor, is a cytokine produced after antigen activation that plays pivotal roles in the immune response 27.…”