Humanized anti-CD154 antibody therapy for the treatment of allograft rejection in nonhuman primates.

The anti-CD154 antibody hu5C8 prevents acute allograft rejection and prolongs allograft survival after withdrawal of therapy in nonhuman primates. This study describes the use of hu5C8 as a rescue agent for rejection developing after the withdrawal of hu5C8. Twelve rhesus monkeys that had received renal allografts under hu5C8 induction and subsequently rejected were studied. Rescue with hu5C8 was analyzed based on the histological character of the rejection (acute versus chronic) and whether conventional therapy was received at the time of rescue or induction. The diagnosis of rejection and response to therapy was based on allograft function and histology. Four monkeys that had acute rejection associated with conventional immunosuppression and hu5C8 were not reversed by hu5C8 rescue. Four animals with isolated chronic rejection following prolonged rejection-free survival after the withdrawal of hu5C8 did not respond to hu5C8 rescue therapy. Hu5C8 rescue therapy effectively reversed acute rejection occurring in two monkeys after hu5C8 withdrawal. One of two animals with combined acute on chronic rejection responded to hu5C8 rescue therapy. Hu5C8 effectively reverses acute but not chronic allograft rejection and appears to have no synergistic effect with conventional rescue agents.

Combination induction therapy with monoclonal antibodies specific for CD80, CD86, and CD154 in nonhuman primate renal transplantation.

BACKGROUND: Antibodies and fusion proteins specific for CD80, CD86, and CD154 have shown promise as agents capable of inducing donor-specific tolerance in rodents. These agents have also been shown to be synergistic with one another in many settings of counter-adaptive immunity. In the nonhuman primate, monoclonal antibodies specific for CD80 and CD86 have prolonged the time to rejection of renal allografts but have not resulted in tolerance. A monoclonal antibody specific for CD154 has resulted in markedly prolonged survival of kidney, islet, cardiac, and skin allografts, but again most animals have eventually developed rejection after prolonged periods of rejection-free survival off therapy. METHODS: A combination of monoclonal antibodies specific for CD80, CD86, and CD154 were used in a mismatched nonhuman primate renal-allograft model. Doses used were based on optimized treatment protocols for each agent individually. RESULTS: Treatment of four rhesus macaques with this combination yielded a mean rejection-free survival of 565 days (311-911 days), significantly greater than untreated controls (mean survival=7.0 days, P=0.001) and animals treated with only a combination of anti-CD80 and CD86 (mean survival=191 days, P=0.01). The survival of animals treated with this combination of monoclonal antibodies was not significantly greater than those treated with anti-CD154 alone, but the production of alloantibody was delayed compared with monotherapy anti-CD154. CONCLUSION: These data suggest that a synergy exists between these agents, particularly with regard to T-dependent B-cell responses, but that they fail to induce durable tolerance in nonhuman primates.