Effects of ASKP1240 combined with tacrolimus or mycophenolate mofetil on renal allograft survival in Cynomolgus monkeys

Abstract

Background: Blocking the CD40-CD154 signal pathway has previously shown promise as a strategy to prevent allograft rejection. In this study, the efficacy of a novel fully human anti-CD40 monoclonal antibody-ASKP1240, administered as a monotherapy or combination therapy (subtherapeutic dose of tacrolimus or mycophenolate mofetil), on the prevention of renal allograft rejection was evaluated in Cynomolgus monkeys.

Methods: Heterotopic kidney transplants were performed in ABO-compatible, stimulation index 2.5 or higher in the two-way mixed lymphocyte reaction monkey pairs. Animals were divided into 12 groups and observed for a maximum of 180 days. Histopathologic, hematology, and biochemistry analyses were conducted in all groups. Cytokine release (interleukin [IL]-2, IL-4, IL-5, IL-6, tumor necrosis factor, and interferon-γ) was investigated in several groups.

Results: ASKP1240 prolonged renal allograft survival in a dose-dependent manner in monotherapy. Low-dose (2 mg/kg) or high-dose (5 mg/kg) ASKP1240, in combination with mycophenolate mofetil (15 mg/kg) or tacrolimus (1 mg/kg), showed a significantly longer allograft survival time compared with monotherapy groups. No obvious side effects including drug-related thromboembolic complications were found. Cytokine release was not induced by ASKP1240 administration.

Conclusion: The present study indicates that ASKP1240, alone or in combination with other immunosuppressive drugs, could be a promising antirejection agent in organ transplantation.

FIGURE 1

Renal allograft survival in each group. For comparison, each ASKP1240 combination therapy group and the relevant control groups were replicated in panels A to F. The curves represent renal graft survival in naive control (gray solid line), tacrolimus or MMF monotherapy (black dot dash line), ASKP1240 monotherapy (gray dotted line), and combination therapy (black dashed line) group. (Tac 0.5=tacrolimus 0.5 mg/kg, Tac 1.0=tacrolimus 1.0 mg/kg, ASKP 2.0=ASKP1240 2.0 mg/kg, ASKP 5.0=ASKP1240 5.0 mg/kg, MMF=15 mg/kg; *P<0.05 ASKP1240 combination group vs. Tacrolimus or MMF monotherapy group, **P<0.01 ASKP1240 combination group versus tacrolimus or MMF monotherapy group, ^#P<0.05 ASKP1240 combination group vs. ASKP1240 monotherapy group). 127×152 mm (600×600 DPI). MMF, mycophenolate mofetil.

FIGURE 2

Renal graft function. A, Mean (±SD) serum creatinine level in each group. The elevation of sCr level was consistent with the occurrence of acute allograft rejection. B, Mean (±SD) BUN level in all groups. Changes of mean BUN levels were similar to sCr. 93×89 mm (600×600 DPI). BUN, blood urea nitrogen, SD, standard deviation; sCr, serum creatinine.

FIGURE 3

Pharmacokinetic evaluation. A, The mean (±SD) serum trough levels of ASKP1240 in groups 3 to 6, 8, and 9, as well as mean (±SD) serum concentration transitions of ASKP1240 in groups 11 and 12. Serum concentrations of ASKP1240 increased in a dose-dependent manner and decreased to relative lower levels 2 weeks after drug administration in maintenance phases. (56BA=before ASKP1240 administration on day 56, 56AA=1 hr after ASKP1240 administration on day 56, day 59=3 days after ASKP1240 administration, day 63=7 days after ASKP1240 administration). B, The mean (±SD) whole blood tacrolimus trough levels increased in a dose-related manner. C, Mean (±SD) plasma trough levels of mycophenolic acid. In general, in the induction phrase, plasma trough levels of mycophenolic acid revealed relatively higher level that was associated with the frequency of MMF administration. The plasma trough levels of mycophenolic acid were stable in maintenance phases. Tac 0.5, tacrolimus 0.5 mg/kg; Tac 1.0, tacrolimus 1.0 mg/kg; ASKP 2.0, ASKP1240 2.0 mg/kg; ASKP 5.0, ASKP1240 5.0 mg/kg; MMF, mycophenolate mofetil 15 mg/kg; SD, standard deviation. 118×157 mm (600×600 DPI).

FIGURE 4

Proportions of histologic types in each group. Acute rejection (red and pink bars) was the only histologic type in Naive and Tac 0.5 groups, and was also the primary histologic type in ASKP 2.0, ASKP 2.0+Tac 0.5, ASKP 5.0+Tac 0.5, and MMF groups. Varying degree of chronic allograft nephropathy (bars with baby blue, cobalt blue or navy blue) constituted the main parts of pathologic findings in the remaining groups. NR, no rejection; NC, nonspecific changes; BC, borderline changes; AR, acute rejection; CAN, chronic allograft nephropathy; Tac 0.5, tacrolimus 0.5 mg/kg; Tac 1.0, tacrolimus 1.0 mg/kg; ASKP 2.0, ASKP1240 2.0 mg/kg; ASKP 5.0, ASKP1240 5.0 mg/kg; MMF, mycophenolate mofetil 15 mg/kg. 117×75 mm (300×300 DPI).