Immunosuppressive therapy sirolimus

Sirolimus is currently the only FDA-approved ToR inhibitor. One of its derivatives, everolimus, is in phase III clinical trials and has been approved for use in some European countries.30 Sirolimus is a macrolide antibiotic that has no effect on cal-cineurin phosphatase.11,31,32 Sirolimus inhibits T cell activation and proliferation by binding to and inhibiting the activation of the mammalian ToR, which suppresses cellular response to IL-2 and other cytokines (i.e., IL-4 and IL-15J.11,31 Studies have shown that sirolimus may be used safely and effectively with either cyclosporine or tacrolimus as a replacement for either azathioprine or mycophenolate mofetil.33 However, when using both sirolimus and cyclosporine as part of a patient s immunosuppressant therapy, because of a drug interaction between the two resulting in a marked increase in sirolimus concentrations, it is recommended to separate the sirolimus and cyclosporine doses by at least 4 hours. Sirolimus also can be used as an alternative agent for patients who do not tolerate calcineurin inhibitors due to nephrotoxicity or other adverse events.34... 

Increased susceptibility to infection and the possible development of lymphoma may result from immunosuppression. Only physicians experienced in immunosuppressive therapy and management of renal transplant patients should use sirolimus. Manage patients receiving the drug in facilities equipped and staffed with adequate laboratory and supportive medical resources. The physician responsible for maintenance therapy should have complete information needed for the follow-up of the patient. Liver transplantation-excess mortality, graft loss, and hepatic artery thrombosis (HAT) The use of sirolimus in combination with tacrolimus was associated with excess mortality and graft loss in a study in de novo liver transplant recipients. Many of these patients had evidence of infection at or near the time of death. 

Lung transplantation-bronchial anastomotic dehiscence Cases of bronchial anastomotic dehiscence, most fatal, have been reported in de novo lung transplant patients when sirolimus has been used as part of an immunosuppressive regimen. The safety and efficacy of sirolimus as immunosuppressive therapy have not been established in liver or lung transplant patients, and therefore, such use is not recommended. 

Immunosuppressive therapy is utilized in chronic severe asthma, where cyclosporine is often effective and sirolimus is another alternative. Omalizumab (anti-IgE antibody) has recently been approved for the treatment of severe asthma (see previous section). Tacrolimus is currently under clinical investigation for the management of autoimmune chronic active hepatitis and of multiple sclerosis, where IFN-3 has a definitive role. 

Systemic immunosuppressive therapies in the treatment of restenosis sirolimus and sirolimus analogs in experimental and clinical data... 

Immunosuppression has concomitant risks of opportunistic infections and secondary tumors. Therefore, the ultimate goal of research on organ transplantation and autoimmune diseases is to induce and maintain immunologic tolerance, the active state of antigen-specific nonresponsiveness. If attainable, tolerance would represent a true cure for conditions discussed above without the side effects of the various immunosuppressive therapies. The calcineurin inhibitors prevent tolerance induction in some, but not aU, preclinical models. In these same model systems, sirolimus does not prevent tolerance and may even promote tolerance induction. 

Clinical uses and pharmacokinetics Use of these immunosuppressants is a major factor in the success of solid organ transplantation. Cyclosporine is used in solid organ transplantation and in graft-versus-host syndrome in bone marrow transplants. Tacrolimus is used in liver and kidney transplant recipients and may be effective as rescue therapy in patients who fail standard therapy. Sirolimus is used alone or in combination with cyclosporine in kidney and heart transplantation. The agents, particularly cyclosporine, may also be effective in immune diseases, including rheumatoid arthritis, uveitis, psoriasis, asthma, and type 1 diabetes. 

Ozcan D, Seckin D, Ada S, Haberal M. Mucocutaneous disorders in renal transplant recipients receiving sirolimus-based immunosuppressive therapy a prospective, case-control study. Clin Transplant 2013 Sep-Oct 27(5) 742-8. PubMed PMID 23991694. Epub 2013/09/03. eng. 

FIGURE 52-2. Center-specific protocols may use RATG, an IL-2RA, or no induction therapy. In any situation, patients receive IV methylprednisolone prior to, during, or immediately following the transplant operation. The patient then will begin the maintenance immunosuppressive regimen. The center-specific protocol will specify which calcineurin inhibitor (cyclosporine or tacrolimus) is used in combination with mycophenolate mofetil or sirolimus with or without steroids. Patients then are monitored for signs and symptoms of rejection. 

Although tacrolimus therapy is associated with increasing blood pressure, studies have found that tacrolimus has less dramatic effects on GFR and RBF than cyclosporine. In some clinical trials, tacrolimus caused less severe HTN and required significantly fewer antihypertensive medications at both 24 and 60 months after transplantation than cyclosporine.61-63 Thus conversion from cyclosporine-based immunosuppression to tacrolimus-based immunosuppression may be one way to minimize blood pressure increases in transplant recipients. Conversion to sirolimus also may be an alternative to the calcineurin inhibitors in patients with difficult-to-treat HTN because sirolimus therapy is less associated with increased blood pressure. Additionally, withdrawal or tapering of steroid therapy may be an effective strategy for lowering blood pressure. 

The first two DES to be commercialized incorporated sirolimus (rapamycin Rapamune , Wyeth Pharmaceuticals, Inc, Collegeville, Pennsylvania, U.S.A.), an immunosuppressive agent used for the prevention of transplanted organ rejection, or paclitaxel (Taxol , Bristol-Myers Squibb, Princeton, New Jersey, U.S.A.) an agent with an extensive history as an anti-cancer therapy. 

Cyclosporine is an important drug in preventing rejection after kidney, hver, heart and other organ transplantation (Haberal et al., 2004). Cyclosporine usually is combined with other immunosuppressives especially glucocorticoids and either azathioprine or mycophenolate mofedl and sirolimus (Krensky et al., 2005). In renal alio transplants it has improved graft acceptance in most clinics to 95 percent. In addition to its use in transplantation cyclosporine is used for the treatment of a number of autoimmune diseases. In autoimmune diseases, as might be anticipated, cyclosporine is most effective in those which are T cell mediated. These include several forms of psoriasis, rheumatoid arthritis refractive to all other therapy, uveitis, nephrotic syndrome and type I diabetes mellitus. 

Outpatient immunosuppressive medications—most commonly, azathioprine, cyclosporine, mycophenolate, prednisone, sirolimus, and tacrolimus—are covered by Medicare Part B. Currently, medicare pays for 80% of immunosuppressive drug therapy. The other 20% is the patient s responsibility. To qualify for Medicare immunosuppressive coverage, the patient must have the following ... 

Monoclonal and polyclonal antibodies directed at reactive T cells are important adjunct therapies and provide a unique opportunity to target specifically immune-reactive cells. Finally, newer small molecules and antibodies have expanded the arsenal of immunosuppressives. In particular, mTOR (mammalian target of rapamycin) inhibitors (sirolimus, everolimus) and anti-CD25 (interleukin [IL]-2 receptor) antibodies (basiliximab, daclizumab) target growth factor pathways, substantially limiting clonal expansion and potentially promoting tolerance. 

A retrospective study of lung and heart transplant patients who received sirolimus-based immunosuppression as a second-line agent after initial therapy with calcinemin inhibitors showed nine patients with cavitatory lung disease. Some patients showed complete resolution, whereas others had... 

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