Testing efficacy of administration of the antiaging drug rapamycin in a nonhuman primate, the common marmoset

Abstract

This report is the first description of dosing procedures, pharmacokinetics, biochemical action, and general tolerability of the antiaging drug rapamycin in the common marmoset, a small and short-lived monkey. Eudragit-encapsulated rapamycin was given orally to trained marmosets in a short-term (3 weeks) and a long-term (14 months) study. Circulating trough rapamycin levels (mean = 5.2 ng/mL; 1.93-10.73 ng/mL) achieved at roughly 1.0 mg/kg/day was comparable to those reported in studies of rodents and within the therapeutic range for humans. Long-term treated animals (6/8) indicated a reduction in mammalian target of rapamycin complex 1 signaling as noted by a decrease in the phospho rpS6 to total rpS6 ratio after 2 weeks of treatment. All long-term treated subjects had detectable concentrations of rapamycin in liver (4.7-19.9 pg/mg) and adipose tissue (2.2-32.8 pg/mg) with reduced mammalian target of rapamycin signaling in these tissues. There was no evidence of clinical anemia, fibrotic lung changes, or mouth ulcers. The observed death rate in the long-term study was as expected given the animals' ages. The ability to rapidly and reliably dose socially housed marmosets with an oral form of rapamycin that is well tolerated and that demonstrates a suppression of the mammalian target of rapamycin pathway leads us to conclude that this species offers a viable model for rapamycin testing to establish safety and efficacy for long-term antiaging intervention.

Keywords: Marmoset; Nonhuman primate.; Rapamycin; mTOR.

© The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1.

Concentrations of rapamycin in yogurt collected every 24 hours following mixing for 1 week to determine the stability of e-rapamycin in a semisolid food item.

Figure 2.

Whole blood rapamycin concentration over a 24-hour time course for animals tested in Trial 1.

Figure 3.

(A) Whole blood rapamycin concentrations over the 3-week dosing phase for four animals tested in Trial 1; (B) marmoset integrated intensity-PBMC fraction phospho-rpS6/total-rpS6 ratio for four animals tested in Trial 1; and (C) Western blots associated with 3-B; see Table 1 for further information on specific subjects. Subjects 5–6 were dosed at 0.20mg/day and subjects 7–8 at 0.40mg/day. A single blot was run and probed with the antibodies listed at the right. The blot was then stripped and reprobed with rpS6 (2217). The 3T3L1 cell line treated with dimethyl sulfoxide/rapamycin/BEZ235 is included as a control.

Figure 3.

(A) Whole blood rapamycin concentrations over the 3-week dosing phase for four animals tested in Trial 1; (B) marmoset integrated intensity-PBMC fraction phospho-rpS6/total-rpS6 ratio for four animals tested in Trial 1; and (C) Western blots associated with 3-B; see Table 1 for further information on specific subjects. Subjects 5–6 were dosed at 0.20mg/day and subjects 7–8 at 0.40mg/day. A single blot was run and probed with the antibodies listed at the right. The blot was then stripped and reprobed with rpS6 (2217). The 3T3L1 cell line treated with dimethyl sulfoxide/rapamycin/BEZ235 is included as a control.

Figure 3.

(A) Whole blood rapamycin concentrations over the 3-week dosing phase for four animals tested in Trial 1; (B) marmoset integrated intensity-PBMC fraction phospho-rpS6/total-rpS6 ratio for four animals tested in Trial 1; and (C) Western blots associated with 3-B; see Table 1 for further information on specific subjects. Subjects 5–6 were dosed at 0.20mg/day and subjects 7–8 at 0.40mg/day. A single blot was run and probed with the antibodies listed at the right. The blot was then stripped and reprobed with rpS6 (2217). The 3T3L1 cell line treated with dimethyl sulfoxide/rapamycin/BEZ235 is included as a control.

Figure 4.

Trough whole blood rapamycin concentrations for animals tested in Trial 2.

Figure 5.

Concentrations of rapamycin in liver and adipose tissue collection following the 11 month dosing in Trial 2 in controls, obese e-rapamycin subjects, and nonobese e-rapamycin subjects.

Figure 6.

Representative blot for phosphorylation of rpS6 in PBMC for animals treated in Trial 2.

Figure 7.

Relative change in phosphorylation of rpS6 in PBMC for control and e-rapamycin-treated animals (including the two obese subjects) before dosing and after 2 weeks of daily dosing in Trial 2.

Figure 8.

Phosphorylation of rpS6 in liver and adipose following the 14-month dosing in Trial 2 (A) Western blots; (B and C) ratios for controls, obese e-rapamycin subjects, and nonobese e-rapamycin subjects.