In vivo evaluation of the novel calcineurin inhibitor ISATX247 in non-human primates.
BACKGROUND
ISA(TX)247 is a novel calcineurin inhibitor that has shown more potency than cyclosporine in vitro. This is the first in vivo study of the effects of ISA(TX)247 on lymphocyte functions in non-human primates.


METHODS
Groups of cynomolgus monkeys were treated orally twice daily for 7 days, each dose consisting of 25 mg/kg cyclosporine (n = 5), 25 mg/kg ISA(TX)247 (n = 6) or 50 mg/kg ISA(TX)247 (n = 6). Levels of cyclosporine and ISA(TX)247 in whole blood were measured by liquid chromatography/mass spectrometry. After mitogen stimulation, lymphocyte proliferation was assessed by tritium-labeled thymidine incorporation and by flow cytometry (expression of proliferating cell nuclear antigen in cells in S/G(2)M phase). Flow cytometry was also used to assess production of intracellular cytokines by T cells (interleukin-2, interferon-gamma, tumor necrosis factor-alpha) and expression of T-cell surface activation antigens (CD25, CD71, CD11a, CD95, CD154).


RESULTS
Trough (C(14 hr)) and peak (C(3 hr)) drug levels, as well as area under the concentration-time curve, were significantly higher for cyclosporine than ISA(TX)247 (370 ng/ml vs 70 ng/ml, 877 ng/ml vs 303 ng/ml and 6,262 ng. h/ml vs 1,979 ng. h/ml, respectively). On Day 7 at C(14 hr), lymphocyte proliferation had been suppressed by approximately 50% in all groups compared with proliferation before treatment. Three hours after dosing, lymphocyte proliferation was inhibited significantly more by ISA(TX)247 (approximately 80%, with no differences between the two ISA(TX)247 dose levels) than by cyclosporine (65% inhibition). Similar differences between the immunosuppressive effects of ISA(TX)247 and cyclosporine were found for inhibition of expression of T-cell surface activation antigens. Despite lower ISA(TX)247 exposures compared with cyclosporine, the cyclosporine treatment only rarely suppressed cytokine production more than treatment with ISA(TX)247.


CONCLUSIONS
In non-human primates, ISA(TX)247 produces a greater or similar inhibition of lymphocyte proliferation, expression of T-cell activation surface antigens, and cytokine production when compared with cyclosporine, despite ISA(TX)247's lower blood levels and total exposure. We conclude that ISA(TX)247 suppresses diverse T-cell functions more potently than cyclosporine in non-human primates in vivo.
Stalder
Mario
M
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
Bîrsan
Tudor
T
Hubble
Richard W
RW
Paniagua
Ricardo T
RT
Morris
Randall E
RE
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D065095:Calcineurin Inhibitors; D016572:Cyclosporine / Q000494:pharmacology*; D016207:Cytokines / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008252:Macaca fascicularis; D008297:Male; D023421:Models, Animal; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology
D015703:Antigens, CD; D065095:Calcineurin Inhibitors; D016207:Cytokines; D007166:Immunosuppressive Agents; C484071:voclosporin; D016572:Cyclosporine