Promising new agents in the prevention of transplant rejection

Promising immunosuppressive drugs designed to prevent rejection have been developed recently. Two monoclonal antibodies directed against the interleukin-2 (IL-2) receptor, daclizumab and basiliximab, have been shown to significantly reduce the incidence of acute rejection without increasing adverse events. Sirolimus (rapamycin), an agent that inhibits T- and B-response at a later stage than cyclosporin, has been shown to be synergistic with cyclosporin in experimental and clinical studies. Ongoing clinical trials have reported that in renal transplantation high doses of sirolimus are as effective as cyclosporin. SDZ-RAD, a derivative of sirolimus, is also under investigation. FTY-720 another promising drug, prolonged the survival of allografts and synergised with cyclosporin and sirolimus in experimental models. Gusperimus (deoxyspergualin), which inhibits IL-1 synthesis, was useful in reversing early and late acute rejection in clinical trials. Antisense oligonucleotides which interfere with intercellular adhesion molecules which are important in rejection, gave encouraging results in primate renal allografts. The availability of these new drugs will be able to further abate the risk of rejection in organ transplantation. However, caution is warranted with their use in order to avoid the risks of over immunosuppression. Today excellent results can be obtained with the available drugs. Newer immunosuppressive schedules should be designed, not only to reduce the risk of rejection, but also to obtain a better therapeutic index that allows a further improvement of the graft survival while minimising the comorbidity and drug-related toxicity.