Decreased incidence of cytomegalovirus infection with sirolimus in a post hoc randomized, multicenter study in lung transplantation.

BACKGROUND: Cytomegalovirus (CMV) is the most common opportunistic infection in lung transplantation. A recent multicenter, randomized trial (the AIRSAC study) comparing sirolimus to azathioprine in lung transplant recipients showed a decreased incidence of CMV events in the sirolimus cohort. To better characterize this relationship of decreased incidence of CMV events with sirolimus, we examined known risk factors and characteristics of CMV events from the AIRSAC database. METHODS: The AIRSAC database included 181 lung transplant patients from 8 U.S.-based lung transplant centers that were randomized to sirolimus or azathioprine at 3 months post-transplantation. CMV incidence, prophylaxis, diagnosis and treatment data were all prospectively collected. Prophylaxis and treatment of CMV were at the discretion of each institution. RESULTS: The overall incidence of any CMV event was decreased in the sirolimus arm when compared with the azathioprine arm at 1 year after lung transplantation (relative risk [RR] = 0.67, confidence interval [CI] 0.55 to 0.82, p < 0.01). This decreased incidence of CMV events with sirolimus remained significant after adjusting for confounding factors of CMV serostatus and CMV prophylaxis. CONCLUSIONS: These data support results from other solid-organ transplantation studies and suggest further investigation of this agent in the treatment of lung transplant recipients at high risk for CMV events.

Interobserver variability in grading transbronchial lung biopsy specimens after lung transplantation.

BACKGROUND: Acute rejection remains a major source of morbidity after lung transplantation. Given the importance of this diagnosis, an international grading system was developed to standardize the diagnosis of acute lung-allograft rejection. The reliability of this grading system has not been adequately assessed by previous studies. METHODS: We examined the level of agreement in grading transbronchial biopsy specimens obtained from a large multicenter study (AIRSAC [Comparison of a Tacrolimus/Sirolimus/Prednisone Regimen vs Tacrolimus/Azathioprine/Prednisone Immunosuppressive Regimen in Lung Transplantation] trial). Biopsy specimens were initially graded for acute rejection and lymphocytic bronchiolitis by the site pathologist and subsequently graded by a central pathologist. Reliability of interobserver grading was evaluated using Cohen κ coefficients. RESULTS: A total of 481 transbronchial biopsy specimens were graded by both the site and central pathologists. The overall concordance rates were 74% and 89% for grade A and grade B biopsy specimens, respectively. When samples from biopsies performed at different time points after transplantation were assessed, there was a higher level of agreement early (≤ 6 weeks) after transplant compared with later time points for acute rejection. However, there was still only moderate agreement for both grade A (κ score 0.479; 95% CI, 0.29-0.67) and grade B (κ score 0.465; 95% CI, 0.08-0.85) rejection. CONCLUSIONS: These results expand upon previous reports of interobserver variability in grading transbronchial biopsy specimens after lung transplantation. Given the variability in grading these specimens, we advocate further education of the histopathologic findings in lung transplant biopsy specimens, as well as revisiting the current criteria for grading transbronchial biopsy specimens to improve concordance among lung transplant pathologists. TRIAL REGISTRY: ClinicalTrials.gov; No. NCT00321906; URL: www.clinicaltrials.gov.

Increased risk of venous thromboembolism with a sirolimus-based immunosuppression regimen in lung transplantation.

BACKGROUND: Sirolimus (rapamycin) is a potent anti-proliferative agent with immunosuppressive properties that is increasingly being used in solid-organ and hematopoietic stem cell transplantation. In addition, this drug is being investigated for treatment of a broad range of disorders, including cardiovascular disease, malignancies, tuberous sclerosis, and lymphangeioleiomyomatosis. In this study, we found an increased risk of venous thromboembolism (VTE) in lung transplant recipients treated with a sirolimus (SIR)-based immunosuppressive regimen. METHODS: One hundred eighty-one lung transplant recipients were enrolled in a prospective, multicenter, randomized, open-label trial comparing a tacrolimus (TAC)/SIR/prednisone immunosuppression regimen with a TAC/azathioprine (AZA)/prednisone immunosuppressive regimen. The differences in rates of VTE were examined. RESULTS: There was a significantly higher occurrence of VTE in the SIR cohort [15 of 87 (17.2%)] compared with the AZA cohort [3 of 94 (3.2%)] (stratified log-rank statistic = 7.44, p < 0.01). When adjusted for pre-transplant diagnosis and stratified by transplant center, this difference remained essentially unchanged (hazard ratio for SIR vs AZA = 5.2, 95% confidence interval 1.4 to 19.5, p = 0.01). CONCLUSION: Clinicians prescribing SIR should maintain a high level of vigilance for VTE, particularly among patients with other risk factors for this complication.

Comparison of sirolimus with azathioprine in a tacrolimus-based immunosuppressive regimen in lung transplantation.

RATIONALE: Lung transplantation has evolved into a life-saving therapy for select patients with end-stage lung diseases. However, long-term survival remains limited because of chronic rejection. Sirolimus is beneficial in preventing cardiac rejection and may decrease rejection after lung transplantation. OBJECTIVES: To determine the potential benefit versus risk of sirolimus in lung transplantation. METHODS: We conducted a multicenter randomized, open label controlled trial comparing sirolimus (SIR) with azathioprine (AZA) in a tacrolimus-based immunosuppressive regimen in lung transplantation. The primary end point was the incidence of acute rejection at 1 year after transplantation between the two study groups. MEASUREMENTS AND MAIN RESULTS: One hundred eighty-one patients were randomized to be included in this study. At 1 year after transplantation, there was no significant difference in the incidence of grade A acute rejection between the two study groups. Similarly, the incidence of chronic rejection and graft survival was no different between the two study groups. Cytomegalovirus infection was decreased in the SIR arm compared with the AZA arm (relative risk, 0.67 [95% confidence interval, 0.55, 0.82]; P < 0.01). There was a higher rate of adverse events leading to early discontinuation of SIR (64%) compared with AZA (49%) during the course of this study. CONCLUSIONS: Sirolimus, an mTOR inhibitor, did not decrease the incidence of acute rejection at 1 year compared with azathioprine in lung transplantation. These results differ from previous results in cardiac and renal transplantation and emphasize the need for multicenter randomized controlled trials in lung transplantation. Clinical trial registered with www.clinicaltrials.gov (NCT 00321906).