15 Sirolimus (rapamycin) for treatment of steroid-refractory chronic graft versus host disease

Sirolimus-Itraconazole Interaction in a Hematopoietic Stem Cell Transplant Recipient

Interactions between azole antifungal agents and immunosuppressants that are metabolized by cytochrome P450 3A4 (chiefly calcineurin inhibitors) are well documented. Interactions between itraconazole and sirolimus are known to occur in patients after solid organ transplantation, but interactions in hematopoietic stem cell transplant (HSCT) recipients have yet to be reported in the literature. We describe an allogeneic HSCT recipient who experienced supratherapeutic trough levels of sirolimus as a result of its coadministration with itraconazole. This patient was a 20-year-old African-American man who underwent HSCT for treatment of myelodysplastic syndrome with severe aplastic anemia. After several regimen changes, the patient received oral itraconazole 200 mg every 12 hours and sirolimus at a dosage of 7 mg/day on days 76-80 and 5 mg/day on days 81 and 82. His sirolimus whole blood trough levels were 17.5 and 35.6 ng/ml on days 80 and 82, respectively (therapeutic range 5-15 ng/ml). An interaction between itraconazole and sirolimus was suspected, and sirolimus was withheld on days 83-90. On day 90, the patient's sirolimus trough level had normalized to 4.4 ng/ml. Sirolimus was resumed at 1-2 mg/day, with adjustments as needed to maintain trough levels of 10-15 ng/ml. Both the itraconazole and sirolimus were eventually were discontinued. The patient died, however, from a disseminated adenovirus infection leading to end-organ failure. Sirolimus is extremely sensitive to the inhibitory potential of azole antifungals. We propose that itraconazole also has a potent effect on sirolimus metabolism. Preemptive sirolimus dosage reduction and close monitoring of its whole blood trough levels are required whenever this combination is considered to avoid immunosuppressant toxicity in already critically ill patients.

Sirolimus and thrombotic microangiopathy after allogeneic hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) may occur after allogeneic hematopoietic stem cell transplantation (HSCT) and is related in part to calcineurin inhibitor toxicity. We observed a higher-than-expected rate of TMA when calcineurin inhibitors were combined with sirolimus. To determine the incidence of and risk factors for TMA after HSCT, we performed a retrospective cohort analysis of myeloablative allogeneic HSCT recipients between 1997 and 2003. TMA diagnosis required the simultaneous occurrence of (1) creatinine increase >2 mg/dL or >50% above baseline, (2) schistocytosis, (3) increased lactate dehydrogenase, and (4) no evidence of disseminated intravascular coagulopathy. A total of 111 sirolimus-exposed subjects were compared with 216 nonexposed subjects after HSCT. TMA occurred in 10.8% of the sirolimus group and 4.2% in the nonsirolimus group (odds ratio, 2.79; P=.03). Sirolimus exposure was associated with TMA earlier than in nonsirolimus patients (25 versus 58 days; P=.04). Only the use of sirolimus (exact odds ratio, 3.49; P=.02) and grade II to IV acute graft-versus-host disease (exact odds ratio, 6.60; P=.0002) were associated with TMA in regression analyses. Treatment of TMA varied among affected individuals. Renal recovery was complete in 92% of sirolimus-treated patients. Overall survival after TMA diagnosis was better for sirolimus subjects than for nonsirolimus subjects (58.3% versus 11.1%; P=.02). Sirolimus seems to potentiate the effects of calcineurin inhibitors on TMA after HSCT. TMA associated with sirolimus seems reversible and has a favorable prognosis when compared with TMA associated with calcineurin inhibitors alone. A careful monitoring strategy for TMA should be used with a sirolimus-containing graft-versus-host disease prophylaxis regimen.

Rapamycin (sirolimus) for treatment of chronic graft-versus-host disease

We conducted a phase II trial in 19 chronic graft-versus-host disease (cGVHD) patients with rapamycin, calcineurin inhibitors, and prednisone with the goals of controlling cGVHD, reducing prednisone use, and defining the safety of this regimen. Rapamycin was begun as second-line (n = 9) or more than second-line (n = 10) therapy. With a median follow-up of 42 months, 16 patients were evaluable for response. Nine patients discontinued rapamycin because of poor compliance/patient request (n = 2) or an adverse event (n = 7), 3 of whom were not evaluable because of withdrawal at < or =1 month or noncompliance. The adverse events included serum creatinine > or =2.4 mg/dL (n = 4), hemolytic uremic syndrome (n = 2), and relapse of malignancy (n = 1). Fifteen of 16 evaluable patients had a clinical response. Five of the 16 discontinued the drug, and 1 died of relapsed leukemia. Of the 10 patients who continued rapamycin, 2 discontinued and 1 successfully tapered all systemic immunosuppression. Three of the 10 developed progressive cGVHD with tapering immunosuppression; all responded to resumption of prior medications. Four of the 10 patients required alternate therapy for persistent or progressive cGVHD while receiving rapamycin; prednisone was discontinued (n = 2) or tapered at the time of progressive disease (n = 2). Seventeen of 19 original patients were alive. One death was due to relapsed malignancy, and 1 was due to congestive heart failure. In this report of rapamycin as cGVHD therapy, there is evidence of rapamycin's efficacy. Given the significant toxicities described, investigation of altered administration of rapamycin and calcineurin inhibitors should be pursued in future cGVHD trials.

Treatment of Gastrointestinal Acute Graft-Versus-Host Disease

Therapy of acute graft-versus-host disease (GVHD) aims to selectively alter the graft- host interactions to foster antitumor effect and minimize antihost effects. The immunosuppression produced by the various therapies ranges from broad, nonselective effects to relatively narrow targeted impact. Despite advances in understanding the pathophysiology of GVHD, newer agents with more selective effects have not yet produced therapeutic advances. The newer targeted agents continue to produce a degree of immunosuppression in which infection and relapse of malignancy are all too common. High-dose systemic steroids remain, as they have for two decades, the initial treatment of choice. Patients failing to respond to steroids continue to represent a challenge, as no second-line therapy is clearly superior to the others. However, some of the new agents appear to be particularly effective in certain organs involved with acute GVHD. For those patients with steroid-refractory GVHD involving primarily the gut, we favor infliximab with concomitant antifungal therapy. For those with primarily skin or liver disease, we favor extracorporeal photochemotherapy.

Sirolimus for GVHD prophylaxis in allogeneic stem cell transplantation

Sirolimus is a novel macrolide immunosuppressant widely used in solid organ transplantation. We have conducted three clinical trials using this compound as prophylaxis against GVHD after allogeneic stem cell transplantation. Our studies have demonstrated excellent GVHD control even when mismatched and unrelated donors were used. The morbidity and mortality associated with transplantation were reduced due to the omission or reduction in methotrexate dose. Furthermore, CMV reactivation and fungal infection rates were low. However, we have noted that sirolimus may be associated with increased rates of thrombotic microangiopathy after transplantation. Sirolimus has other uses, such as the treatment of established acute and chronic GVHD, and may be useful for treatment of post transplant lymphoproliferative disorder and perhaps as an antineoplastic agent against a wide variety of hematologic and solid neoplasms.

Sirolimus and tacrolimus without methotrexate as graft-versus-host disease prophylaxis after matched related donor peripheral blood stem cell transplantation

Methotrexate in combination with a calcineurin inhibitor is a standard graft-versus-host disease (GVHD) prophylactic regimen in allogeneic stem cell transplantation. However, methotrexate is associated with delayed engraftment, mucositis, idiopathic pneumonia syndrome, and other transplant-related complications. Sirolimus, a novel immunosuppressant without methotrexate's toxicities, has been used successfully in solid organ transplantation. We hypothesized that replacing methotrexate with sirolimus would preserve effective prophylaxis of GVHD while minimizing transplant-related toxicity after allogeneic peripheral blood stem cell transplantation. We enrolled 30 patients in a phase II study to test the efficacy of tacrolimus in combination with sirolimus in lieu of methotrexate in preventing GVHD after allogeneic peripheral blood stem cell transplantation from HLA-matched related donors. Grade II GVHD occurred in 3 patients (10%), and no patient developed grade III or IV GVHD. Neutrophil and platelet engraftment were prompt, occurring on days 14 and 13, respectively. All patients survived to hospital discharge (median, 18 days), and peritransplantation toxicity was mild. Four patients developed thrombotic microangiopathy, and 3 patients developed hepatic veno-occlusive disease. Chronic GVHD occurred in 11 patients. Relapse-free and overall survival at 100 days were 93% and 97%, respectively, and were 71% and 67% at 1 year. Causes of death included relapse (n = 6), veno-occlusive disease (n = 1), and late pulmonary toxicity (n = 1). Sirolimus in combination with tacrolimus is a promising alternative to methotrexate-based regimens for GVHD prophylaxis after matched related donor peripheral blood stem cell transplantation. Mucositis was modest, engraftment was prompt, and transplant-related toxicity was modest. Methotrexate-free, sirolimus-based GVHD prophylactic regimens should be tested in randomized trials against the current standard of care.