Characterization of ASKP1240, a fully human antibody targeting human CD40 with potent immunosuppressive effects.

Blocking the CD40-CD154 interaction is reported to be effective for transplantation management and autoimmune disease models in rodents and nonhuman primates. However, clinical trials with anti-CD154 mAbs were halted because of high incidence of thromboembolic complications. Thus, we generated and characterized a fully human anti-CD40 mAb ASKP1240, as an alternative to anti-CD154 mAb. In vitro ASKP1240 concentration-dependently inhibited human peripheral blood mononuclear cell proliferation induced by soluble CD154. In addition, ASKP1240 did not destabilize platelet thrombi under physiological high shear conditions while mouse anti-human CD154 mAb (mu5C8) did. And ASKP1240 itself did not activate platelet and endothelial cells. In vivo administration of ASKP1240 (1 or 10 mg/kg, intravenously) to cynomolgus monkeys, weekly for 3 weeks, significantly attenuated both delayed-type hypersensitivity and specific antibody formation evoked by tetanus toxoid. The immunosuppressive effect was well correlated with the CD40 receptor saturation. Thus, these results suggest that ASKP1240 is immunosuppressive but not prothromboembolic, and as such appears to be a promising therapeutic candidate for the management of solid organ transplant rejection and autoimmune diseases therapy.

ASKP1240, a fully human anti-CD40 monoclonal antibody, prolongs pancreatic islet allograft survival in nonhuman primates.

A strategy for inhibiting CD40 has been considered as an alternative approach for immunosuppression because of undesirable effects of anti-CD154 monoclonal antibodies (mAbs). Previously, we demonstrated that ASKP1240, which is a fully human anti-CD40 mAb, significantly prolonged kidney and liver allograft survival in cynomolgus monkeys without causing thromboembolic complications. Herein, we evaluated the effect of ASKP1240 on pancreatic islet transplantation (PITx) in cynomolgus monkeys. Diabetes was induced by total pancreatectomy, and islet allografts were transplanted into the liver. Following PITx (8201-12 438 IEQ/kg), blood glucose levels normalized promptly in all animals. Control islet allografts were rejected within 9 days (n = 3), whereas ASKP1240 (10 mg/kg) given on postoperative days 0, 4, 7, 11 and 14 (induction treatment, n = 5) significantly prolonged graft survival time (GST) to >15, >23, 210, 250 and >608 days, respectively. When ASKP1240 (5 mg/kg) was administered weekly thereafter up to post-PITx 6 months (maintenance treatment, n = 4), GST was markedly prolonged to >96, >115, 523 and >607 days. During the ASKP1240 treatment period, both anti-donor cellular responses and development of anti-donor antibodies were abolished, and no serious adverse events were noted. ASKP1240 appears to be a promising candidate for immunosuppression in clinical PITx.

Long-term hepatic allograft acceptance based on CD40 blockade by ASKP1240 in nonhuman primates.

Blockade of the CD40-CD154 costimulatory signal is an attractive strategy for immunosuppression and tolerance induction in organ transplantation. Treatment with anti-CD154 monoclonal antibodies (mAbs) results in potent immunosuppression in nonhuman primates (NHPs). Despite plans for future clinical use, further development of these treatments was halted by complications. As an alternative approach, we have been focusing on the inhibition of the counter receptor, CD40 and have shown that a novel human anti-CD40 mAb, ASKP1240, markedly prolongs renal allograft survival in NHPs, although allografts eventually underwent chronic allograft nephropathy. On the basis of our previous findings that a CD40-CD154 costimulation blockade induces tolerance to hepatic, but not cardiac, allografts in rodents, we tested here our hypothesis that a blockade of CD40 by ASKP1240 allows acceptance of hepatic allografts in NHPs. A 2-week ASKP1240 induction treatment prolonged liver allograft survival in NHPs; however, the graft function deteriorated due to chronic rejection. In contrast, a 6-month ASKP1240 maintenance monotherapy efficiently suppressed both cellular and humoral alloimmune responses and prevented rejection on the hepatic allograft. No serious side effects, including thromboembolic complications, were noted in the ASKP1240-treated monkeys. We conclude that CD40 blockade by ASKP1240 would be a desirable immunosuppressant for clinical liver transplantation.

A human anti-CD40 monoclonal antibody, 4D11, for kidney transplantation in cynomolgus monkeys: induction and maintenance therapy.

Blockade of CD40-CD154 signaling pathway is an attractive strategy to induce potent immunosuppression and tolerance in organ transplantation. Due to its strong immunosuppressive effect shown in nonhuman primate experiments, anti-CD154 monoclonal antibodies (mAbs) have been tried in clinical settings, but it was interrupted by unexpected thromboembolic complications. Thus, inhibition of the counter molecule, CD40, has remained an alternative approach. In the previous preliminary study, we have shown that 4D11, a novel fully human anti-CD40 mAb, has a fairly potent immunosuppressive effect on kidney allograft in nonhuman primates. In this study, we aimed to confirm the efficacy and untoward events of the 2-week induction and 180-day maintenance 4D11 treatments. In both, 4D11 significantly suppressed T-cell-mediated alloimmune responses and prolonged allograft survival. Addition of weekly 4D11 administration after the induction treatment further enhanced graft survival. Complete inhibition of both donor-specific Ab and anti-4D11 Ab productions was obtained only with higher-dose maintenance therapy. No serious side effect including thromboembolic complications was noted except for a transient reduction of hematocrit in one animal, and decrease of peripheral B-cell counts in all. These results indicate that the 4D11 appears to be a promising candidate for immunosuppression in clinical organ transplantation.

Study on surfactin, a cyclic depsipeptide. II. Synthesis of surfactin B2 produced by Bacillus natto KMD 2311.

The total synthesis of surfactin B2, a cyclic depsipeptide isolated from Bacillus natto KMD 2311, was achieved to elucidate the absolute configuration of its fatty acid moiety. This is the first chemical confirmation of the absolute configuration of a surfactin homolog. Two possible diastereoisomers of surfactin B2, cyclo[D- and L-3-(Glu-Leu-D-Leu-Val-Asp-D-Leu-Leu-O)-n-tetradecanoyl] (1a and b), were synthesized by a solution method using mainly active ester and azide fragment condensation methods. Cyclization reaction of the partially protected linear depsipeptide containing the C-terminal N-succinimidyl active ester in pyridine by the high dilution method at room temperature for 3d gave the desired cyclic depsipeptide in a high yield of about 70%. The synthetic product 1a, containing the D-isomer of 3-hydroxytetradecanoic acid as a fatty acid moiety, was identical with natural surfactin B2.

Contractile activity of porcine neuromedin U-25 and various neuromedin U-related peptide fragments on isolated chicken crop smooth muscle.

Contractile activity of porcine neuromedin U-25 (p-NMU-25) and various neuromedin U (NMU) peptide fragment amides was examined on chicken crop smooth muscle preparation. The relative activity (expressed as RA value) of p-NMU-25 to porcine neuromedin U-8 (p-NMU-8) was 5.51 +/- 0.09, and p-NMU-25 (15-25) was the most potent fragment with an RA value of 7.78 +/- 0.05. All C-terminal 11-peptide amides of rat, rabbit, and frog NMU peptides retained activity about three-fold higher than the corresponding C-terminal 8-peptide amides. The peptide segment Asn15-Arg-Arg17 of p-NMU-25, as well as the corresponding positions of various NMU peptides: Ser13-Gly-Gly15 of rat NMU and Ser15-Arg-Gly17 of rabbit and frog NMUs, appeared to be involved in the structural requirements for increased contractile activity in the assay system.

Agonistic and antagonistic activities of neuromedin U-8 analogs substituted with glycine or D-amino acid on contractile activity of chicken crop smooth muscle preparations.

To study the structure-activity relationships of neuromedin U-8 (NMU-8) (H-Tyr-Phe-Leu-Phe-Arg-Pro-Arg-Asn-NH2) and to develop a NMU-8 antagonist, twenty-three NMU-8 analogs substituted with Gly or the corresponding D-amino acid(s) at positions 1-8 were synthesized by solid-phase techniques. On isolated chicken crop preparations, the contractile activity of the synthetic NMU-8 analogs was compared with that of NMU-8 and their antagonistic activity was assayed against NMU-8. The replacement of Phe2, Phe4, Arg5, Pro6, Arg7 or Asn8 with Gly brought about a drastic decrease of the agonistic activities. Substitution of the corresponding D-amino acid residue for Phe2, Phe4, Arg5, Pro6 or Asn8 caused a marked decrease of the agonistic activities, while the replacement of Tyr1 with D-form enhanced the activity. It was further revealed that [D-Pro6]-NMU-8 and [D-Leu3, D-Pro6]-NMU-8 exerted a non-competitive antagonistic activity against NMU-8 with x values of 5.22 +/- 0.12 and 5.34 +/- 0.09, respectively. [D-Phe2, D-Pro6]-NMU-8, [D-Arg5, D-Pro6]-NMU-8 and [D-Pro6, D-Asn8]-NMU-8 showed a very weak antagonism. The results indicated that 1) the side chain of each amino acid at positions 2, 4, 5, 6, 7 and 8 of NMU-8 is of relative importance for the expression of the contractile activity, and 2) [D-Pro6]-NMU-8 and its four analogs acted as an antagonist against NMU-8.

Structure-activity relationships of rat neuromedin U for smooth muscle contraction.

Rat neuromedin U (r-NMU) and its fragment peptide amides were synthesized by solid-phase methodology. Using a chicken crop smooth muscle contraction assay, the potency of r-NMU and its fragments relative to porcine neuromedin U-8 (p-NMU-8) was r-NMU: 10.25 +/- 2.88, r-NMU (6-23): 8.01 +/- 1.04, r-NMU (10-23): 2.76 +/- 0.46, r-NMU (13-23): 2.81 +/- 0.52, and r-NMU (16-23): 0.88 +/- 0.19, respectively. Two heptapeptides, r-NMU (17-23) and r-NMU (16-22), had a relative potency of 0.61 and 0.03 respectively, and elicited maximal contraction at a dose of 10 microM to a similar degree to p-NMU-8. The other shorter C-terminal fragments did not elicit the maximal contraction or any activity. In a rat uterus contraction assay, r-NMU (13-23), but not r-NMU (16-23), at a dose of 4 nM retained as high a stimulatory activity as r-NMU itself. r-NMU (17-22) was the smallest peptide fragment to elicit the maximal sustained contraction at 10 microM. These results indicate that the amino acid sequence Phe-Leu-Phe-Arg-Pro-Arg, corresponding to positions 17 to 22 of r-NMU, may be essential for contractile activity. N-terminal peptide segments Tyr-Gln-Gly-Pro corresponding to positions 6 to 9, and Ser-Gly-Gly corresponding to positions 13 to 15, appear to be of special importance for potent activity.