Sirolimus-induced pneumonitis: three cases and a review of the literature

A Pediatric Case of Sirolimus-Associated Pneumonitis After Kidney Transplantation

Sirolimus is an immunosuppressive medication often used in solid organ transplantation. It has been associated with severe side effects, including pulmonary toxicity. In adult patients, a single center study found that 14% of those treated with sirolimus developed pulmonary pneumonitis; however, the incidence in the pediatric population is not known. Most reports in adult patients indicate that elevated drug concentrations and a prolonged duration of use are associated with pulmonary toxicity. We report a case of a 17-year-old male kidney transplant recipient who developed rapid-onset respiratory failure, necessitating mechanical ventilation and acute renal replacement therapy for ultrafiltration secondary to sirolimus-induced pneumonitis. He had been treated for acute rejection with corticosteroids 17 days prior to the development of pneumonitis. His symptoms developed within 1 week of initiation of sirolimus and with a serum concentration of 1.1 ng/mL. Sirolimus was discontinued, and, following aggressive diuresis and ventilatory support, his respiratory status returned to baseline. Sirolimus-induced pneumonitis is an important diagnosis to be considered in any transplant recipient receiving sirolimus with new onset fever, cough, or dyspnea without an identifiable source, especially if there is a preceding history of treatment with high-dose corticosteroids.

Immune Modulation of Head and Neck Squamous Cell Carcinoma and the Tumor Microenvironment by Conventional Therapeutics

Head and neck squamous cell carcinoma (HNSCC) accounts for more than 600,000 cases and 380,000 deaths annually worldwide. Although human papillomavirus (HPV)-associated HNSCCs have better overall survival compared with HPV-negative HNSCC, loco-regional recurrence remains a significant cause of mortality and additional combinatorial strategies are needed to improve outcomes. The primary conventional therapies to treat HNSCC are surgery, radiation, and chemotherapies; however, multiple other targeted systemic options are used and being tested including cetuximab, bevacizumab, mTOR inhibitors, and metformin. In 2016, the first checkpoint blockade immunotherapy was approved for recurrent or metastatic HNSCC refractory to platinum-based chemotherapy. This immunotherapy approval confirmed the critical importance of the immune system and immunomodulation in HNSCC pathogenesis, response to treatment, and disease control. However, although immuno-oncology agents are rapidly expanding, the role that the immune system plays in the mechanism of action and clinical efficacy of standard conventional therapies is likely underappreciated. In this article, we focus on how conventional and targeted therapies may directly modulate the immune system and the tumor microenvironment to better understand the effects and combinatorial potential of these therapies in the context and era of immunotherapy.

Inhibition of mTOR Signaling and Clinical Activity of Rapamycin in Head and Neck Cancer in a Window of Opportunity Trial

PURPOSE

We studied the impact of mTOR signaling inhibition with rapamycin in head and neck squamous cell carcinoma (HNSCC) in the neoadjuvant setting. The goals were to evaluate the mTOR pathway as a therapeutic target for patients with advanced HNSCC, and the clinical safety, antitumor, and molecular activity of rapamycin administration on HNSCC.

PATIENTS AND METHODS

Patients with untreated stage II-IVA HNSCC received rapamycin for 21 days (day 1, 15 mg; days 2-12, 5 mg) prior to definitive treatment with surgery or chemoradiation. Treatment responses were assessed clinically and radiographically with CT and FDG-PET. Pre- and posttreatment biopsies and blood were obtained for toxicity, immune monitoring, and IHC assessment of mTOR signaling, as well as exome sequencing.

RESULTS

Sixteen patients (eight oral cavity, eight oropharyngeal) completed rapamycin and definitive treatment. Half of patients were p16 positive. One patient had a pathologic complete response and four (25%) patients met RECIST criteria for response (1 CR, 3 PR, 12 SD). Treatment was well tolerated with no grade 4 or unexpected toxicities. No significant immune suppression was observed. Downstream mTOR signaling was downregulated in tumor tissues as measured by phosphorylation of S6 (P < 0.0001), AKT (P < 0.0001), and 4EBP (P = 0.0361), with a significant compensatory increase in phosphorylated ERK in most patients (P < 0.001). Ki67 was reduced in tumor biopsies in all patients (P = 0.013).

CONCLUSIONS

Rapamycin treatment was well tolerated, reduced mTOR signaling and tumor growth, and resulted in significant clinical responses despite the brief treatment duration, thus supporting the potential role of mTOR inhibitors in treatment regimens for HNSCC.

Evaluation after Orthotopic Heart Transplant: What the Radiologist Should Know

Orthotopic heart transplant (OHT) is the treatment of choice for end-stage heart disease. As OHT use continues and postoperative survival increases, multimodality imaging evaluation of the transplanted heart will continue to increase. Although some of the imaging is performed and interpreted by cardiologists, a substantial proportion of images are read by radiologists. Because there is little to no consensus on a systematic approach to patients after OHT, radiologists must become familiar with common normal and abnormal posttreatment imaging features. Intrinsic transplant-related complications may be categorized on the basis of time elapsed since transplant into early (0-30 days), intermediate (1-12 months), and late (>12 months) stages. Although there can be some overlap between stages, it remains helpful to consider the time elapsed since surgery, because some complications are more common at certain stages. Recognition of differing OHT surgical techniques and their respective postoperative imaging features helps to avoid image misinterpretation. Expected early postoperative findings include small pneumothoraces, pleural effusions, pneumomediastinum, pneumopericardium, postoperative atelectasis, and an enlarged cardiac silhouette. Early postoperative complications also can include sternal dehiscence and various postoperative infections. The radiologist's role in the evaluation of allograft failure and rejection, endomyocardial biopsy complications, cardiac allograft vasculopathy, and posttransplant malignancy is highlighted. Because clinical manifestations of disease may be delayed in transplant recipients, radiologists often recognize postoperative complications on the basis of imaging and may be the first to suggest a specific diagnosis and thus positively affect patient outcomes. Online supplemental material is available for this article. ^©RSNA, 2019.

mTOR co-targeting strategies for head and neck cancer therapy

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. There is an urgent need to develop effective therapeutic approaches to prevent and treat HNSCC. Recent deep sequencing of the HNSCC genomic landscape revealed a multiplicity and diversity of genetic alterations in this malignancy. Although a large variety of specific molecules were found altered in each individual tumor, they all participate in only a handful of driver signaling pathways. Among them, the PI3K/mTOR pathway is the most frequently activated, which plays a central role in cancer initiation and progression. In turn, targeting of mTOR may represent a precision therapeutic approach for HNSCC. Indeed, mTOR inhibition exerts potent anti-tumor activity in HNSCC experimental systems, and mTOR targeting clinical trials show encouraging results. However, advanced HNSCC patients may exhibit unpredictable drug resistance, and the analysis of its molecular basis suggests that co-targeting strategies may provide a more effective option. In addition, although counterintuitive, emerging evidence suggests that mTOR inhibition may enhance the anti-tumor immune response. These new findings raise the possibility that the combination of mTOR inhibitors and immune oncology agents may provide novel precision therapeutic options for HNSCC.

Sirolimus-Induced Combined Posterior Reversible Encephalopathy Syndrome and Lymphocytic Pneumonitis in a Renal Transplant Recipient: Case Report and Review of the Literature

The mammalian target of rapamycin inhibitor sirolimus was introduced into clinical transplant practice in 1999. Dose-related myelosuppression and hyper lipidemia are the most common adverse effects. Pulmonary toxicity has been reported since 2004 and can cause interstitial pneumonitis, organizing pneumonia, and alveolar hemorrhage. Moreover, it can occasionally induce posterior reversible encephalopathy syndrome, as documented in scarce reports. To our knowledge; this is the 1st report of combined posterior reversible encephalopathy syndrome and lymphocytic pneumonitis to be induced by sirolimus. Here, we present a renal transplant recipient with reversible sirolimus-induced brain lesions who was diagnosed after exclusion of infections (viral, bacterial, and fungal), tumors, sarcoidosis, and autoimmune disorders. Both brain lesions and pneumonitis resolved completely after sirolimus discontinuation with excellent patient and graft outcome. Early and gradual sirolimus withdrawal can reverse posterior reversible encephalopathy syndrome and lymphocytic pneumonitis with preservation of stable graft function.

Control of PD-L1 Expression by Oncogenic Activation of the AKT-mTOR Pathway in Non-Small Cell Lung Cancer

Alterations in EGFR, KRAS, and ALK are oncogenic drivers in lung cancer, but how oncogenic signaling influences immunity in the tumor microenvironment is just beginning to be understood. Immunosuppression likely contributes to lung cancer, because drugs that inhibit immune checkpoints like PD-1 and PD-L1 have clinical benefit. Here, we show that activation of the AKT-mTOR pathway tightly regulates PD-L1 expression in vitro and in vivo. Both oncogenic and IFNγ-mediated induction of PD-L1 was dependent on mTOR. In human lung adenocarcinomas and squamous cell carcinomas, membranous expression of PD-L1 was significantly associated with mTOR activation. These data suggest that oncogenic activation of the AKT-mTOR pathway promotes immune escape by driving expression of PD-L1, which was confirmed in syngeneic and genetically engineered mouse models of lung cancer where an mTOR inhibitor combined with a PD-1 antibody decreased tumor growth, increased tumor-infiltrating T cells, and decreased regulatory T cells.

Interstitial Lung Disease Associated with mTOR Inhibitors in Solid Organ Transplant Recipients: Results from a Large Phase III Clinical Trial Program of Everolimus and Review of the Literature

Interstitial lung disease (ILD) has been reported with the use of mammalian target of rapamycin inhibitors (mTORi). The clinical and safety databases of three Phase III trials of everolimus in de novo kidney (A2309), heart (A2310), and liver (H2304) transplant recipients (TxR) were searched using a standardized MedDRA query (SMQ) search for ILD followed by a case-by-case medical evaluation. A literature search was conducted in MEDLINE and EMBASE. Out of the 1,473 de novo TxR receiving everolimus in Phase III trials, everolimus-related ILD was confirmed in six cases (one kidney, four heart, and one liver TxR) representing an incidence of 0.4%. Everolimus was discontinued in three of the four heart TxR, resulting in ILD improvement or resolution. Outcome was fatal in the kidney TxR (in whom everolimus therapy was continued) and in the liver TxR despite everolimus discontinuation. The literature review identified 57 publications on ILD in solid organ TxR receiving everolimus or sirolimus. ILD presented months or years after mTORi initiation and symptoms were nonspecific and insidious. The event was more frequent in patients with a late switch to mTORi. In most cases, ILD was reversed after prompt mTORi discontinuation. ILD induced by mTORi is an uncommon and potentially fatal event warranting early recognition and drug discontinuation.

Pulmonary toxicity in a renal transplant recipient treated with amiodarone and everolimus: a case of hypothetical synergy and a proposal for a screening protocol

Pneumotoxic drugs like amiodarone and m-TOR inhibitors (m-TORi) may be administered contemporaneously in therapy for patients who had renal transplants. We present a case of amiodarone pulmonary toxicity (APT) in a patient treated with amiodarone and everolimus. A 57-year-old Caucasian male, under treatment with both everolimus (for 3 years) and amiodarone (for 2 months), presented with fever, dyspnoea and a negative chest X-ray after his second kidney transplant with suboptimal serum creatinine (3 mg/dl). A non-contrastive high-resolution CT scan showed bilateral interstitial lung disease with an associated reduction in carbon monoxide diffusing capacity. Bronchoalveolar lavage (BAL) was negative for an infection, but BAL cytology was suitable for APT (50% of ‘foamy’ macrophages). A complete recovery was achieved after amiodarone interruption and an oral steroid therapy increase. Everolimus was continued. His kidney function remained unchanged in the upcoming months. In conclusion, we suggest a possible synergistic effect between m-TORi and amiodarone. Furthermore, we propose a diagnostic algorithm that can be used as a surveillance tool to identify a potential initial lung damage in patients treated with 1 or more pneumotoxic drugs.

Low dose rapamycin exacerbates autoimmune experimental uveitis

Background

Rapamycin, a potent immune modulator, is used to treat transplant rejection and some autoimmune diseases. Uveitis is a potentially severe inflammatory eye disease, and 2 clinical trials of treating uveitis with rapamycin are under way. Unexpectedly, recent research has demonstrated that low dose rapamycin enhances the memory T cell population and function. However, it is unclear how low dose rapamycin influences the immune response in the setting of uveitis.

Design and Methods

B10.RIII mice were immunized to induce experimental autoimmune uveitis (EAU). Ocular inflammation of control and rapamycin-treated mice was compared based on histological change. ELISPOT and T cell proliferation assays were performed to assess splenocyte response to ocular antigen. In addition, we examined the effect of rapamycin on activation-induced cell death (AICD) using the MitoCapture assay and Annexin V staining.

Results

Administration of low dose rapamycin exacerbated EAU, whereas treating mice with high dose rapamycin attenuated ocular inflammation. The progression of EAU by low dose rapamycin coincided with the increased frequency of antigen-reactive lymphocytes. Lastly, fewer rapamycin-treated T cells underwent AICD, which might contribute to exaggerated ocular inflammation and the uveitogenic immune response.

Conclusion

These data reveal a paradoxical role for rapamycin in uveitis in a dose-dependent manner. This study has a potentially important clinical implication as rapamycin might cause unwanted consequences dependent on dosing and pharmacokinetics. Thus, more research is needed to further define the mechanism by which low dose rapamycin augments the immune response.

Sirolimus-induced pneumonitis complicated by pentamidine-induced phospholipidosis in a renal transplant recipient: a case report

The proliferation signal inhibitors (PSIs)-sirolimus, everolimus, and temsirolimus-have been associated with a noninfectious pneumonitis characterized by lymphocytic alveolitis and bronciolitis obliterans with organizing pneumonia (BOOP). This condition usually occurs within the first year. Herein we presented a case of a deceased donor renal transplant with interstitial pneumonitis developing 6 years after a switch from tacrolimus to sirolimus due to chronic graft dysfunction. After the addition of intravenous pentamidine due to the suspicion of Pneumocystis pneumonia, there was marked clinical deterioration requiring intubation. Open lung biopsy revealed sirolimus-induced pulmonary toxicity (BOOP) with the additional finding of a drug-induced phospholipidosis (DIPL) that we ascribe to pentamidine treatment. After cessation of both drugs and application of corticosteroid therapy, there was only partial improvement. Eight months later the residual interstitial fibrosis demands supplemental home oxygen. We review the literature on PSI-induced pneumonitis and discuss the pathophysiology of a potential interaction with pentamidine. We caution against its use in the setting of PSI-induced pneumonitis. It is currently unknown whether these concerns also apply to prescription of other more commonly used medications associated with DIPL, eg, amiodarone and aminoglycosides.

An investigator-driven study of everolimus in surgical lung biopsy confirmed idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

We evaluated the efficacy and safety of everolimus, a macrocyclic proliferation signal inhibitor with anti-fibroproliferative activity to prevent disease progression or death in patients with IPF, a progressive, fatal disease with no known effective therapy.

METHODS

Eighty-nine patients with surgical lung biopsy confirmed IPF were enrolled in a 3-year investigator-driven, placebo-controlled, double-blinded, multicentre study of everolimus.

RESULTS

The everolimus (n = 44) and placebo (n = 45) groups were matched for demographic variables (gender, P = 0.46) and baseline lung function parameters (FVC, P = 0.29; TLC, P = 0.45; DL(CO) , P = 0.41 and PaO(2) , P = 0.34). Independent risks for disease progression were everolimus (hazard ratio (HR) 2.37, 95% CI: 1.40-4.00, P < 0.01, log rank) and male gender (HR 2.76, 95% CI: 1.47-5.17, P < 0.01, log rank). Three-year transplant-free survival was 36 ± 7% (everolimus) versus 51 ± 8% (placebo) (Kaplan-Meier, P = 0.11, log rank). Independent risks for transplant-free survival were male gender (HR 2.33, 95% CI: 1.07-5.05, P = 0.03, log rank) and baseline DL(CO) (% predicted) (HR 0.96, 95% CI: 0.93-0.99, P = 0.02, log rank).

CONCLUSIONS

Everolimus use was associated with more rapid disease progression in a well-defined cohort of patients with IPF confirmed by surgical lung biopsy followed for 3 years.

Indications and effectiveness of the mammalian target of rapamycin in liver transplantation

BACKGROUND

The mammalian target of rapamycin (mTOR) inhibitors are new immunosuppressive drugs for organ transplantation. They are interesting for liver transplantation because of their absence of nephrotoxicity and potential antitumor effects, because calcineurin inhibitors (CNI) are associated with renal dysfunction post-CNI and tumors. We sought to analyze the indications, safety, and efficacy of mTOR among liver transplant patients at our center.

METHODS

We retrospectively identified patients who were treated with mTOR for their indications for liver transplantation, type of immunosuppressive therapy, acute rejection episodes, and evolution of kidney function.

RESULTS

We identified 43 (19.02%) patients treated with mTOR including 35 (81.4%) males and 8 (18.6%) females of overall average age of 56.7 (range, 44-68). In 30% of patients, the drug was introduced for kidney failure, and in 23% for actual or a high risk of hepatocellular carcinoma (HCC) recurrence. The average time to introduction of the mTOR was 6.4 months (range, 1-46). The final immunosuppressive regimen was mTOR alone (73%), or mTOR plus CNI (23%), or mTOR plus mycophenolate mofetil (4%). The average values of creatinine and urea were lower after conversion to mTOR (P < .05) with a 6.9% incidence of acute rejection episodes.

CONCLUSION

The mTOR immunosuppressive drugs are safe for liver transplant patients, effectively controlling renal dysfunction. They can be used in other indications, such as neurotoxicity, de novo tumors, and high risk of HCC recurrence. More studies are needed to clarify their long-term effectiveness.

[Pneumocystis jiroveci infection associated with organizing pneumonia in a kidney transplant patient]

The authors report the association of organizing pneumonia (OP) and a Pneumocystis jiroveci infection in a woman who benefited from a kidney transplant 13 years before and was under corticoids, cyclosporine and mycophenolate mofetil. The diagnosis was based on progressive dyspnoea with fever with an alteration in the general state associated with diffuse micronodular pneumopathy suggesting bronchiolitis. The conformation was obtained by the analysis of the alveolar bronchial washings and the histological examination of the distal biopsies revealing endo-alveolar vegetant fibromas. Transbronchial biopsies may be used for the diagnosis and thereby, avoid an invasive surgical pulmonary biopsy. The aetiology of OP may be related to the immunosuppressant treatment or infection by Pneumocystis jiroveci. The evolution in this case was favourable with trimethoprime and sulfamethoxazole associated with a transient increase in the corticoid treatment. This association is rarely described in patients undergoing solid organ transplants.

Overview of immunosuppression in liver transplantation

Continued advances in surgical techniques and immunosuppressive therapy have allowed liver transplantation to become an extremely successful treatment option for patients with end-stage liver disease. Beginning with the revolutionary discovery of cyclosporine in the 1970s, immunosuppressive regimens have evolved greatly and current statistics confirm one-year graft survival rates in excess of 80%. Immunosuppressive regimens include calcineurin inhibitors, anti-metabolites, mTOR inhibitors, steroids and antibody-based therapies. These agents target different sites in the T cell activation cascade, usually by inhibiting T cell activation or via T cell depletion. They are used as induction therapy in the immediate peri- and post-operative period, as long-term maintenance medications to preserve graft function and as salvage therapy for acute rejection in liver transplant recipients. This review will focus on existing immunosuppressive agents for liver transplantation and consider newer medications on the horizon.

The use of everolimus in renal-transplant patients

Despite advances in immunosuppressive therapy, long-term renal-transplantation outcomes have not significantly improved over the last decade. The nephrotoxicity of calcineurin inhibitors (CNIs) is an important cause of chronic allograft nephropathy (CAN), the major driver of long-term graft loss. Everolimus is a proliferation signal inhibitor with a mechanism of action that is distinct from CNIs. The efficacy and tolerability of everolimus in renal-transplant recipients have been established in a wide range of clinical trials. Importantly, synergism between everolimus and the CNI cyclosporine (CsA) permits CsA dose reduction, enabling nephrotoxicity to be minimized without compromising efficacy. Currently, everolimus is being investigated in regimens where reduced exposure CNIs are used from the initial post-transplant period to improve renal function and prevent CAN. By inhibiting the proliferation of smooth muscle cells, everolimus may itself delay the progression or development of CAN. Although everolimus is associated with specific side effects, these can generally be managed. By targeting the main causes of short- and long-term graft loss, everolimus has a key role to play in renal transplantation, which is being explored further in a number of ongoing Phase III–IV trials.

An unusual presentation of sirolimus associated cough in a renal transplant recipient

Sirolimus-associated pulmonary problems are rare but life threatening. Pulmonary problems due to sirolimus treatment are interstitial pneumonitis, bronchiolitis obliterans organizing pneumonia (BOOP), and alveolar hemorrhage. We present a case of sirolimus-related cough in the absence of any pulmonary radiological findings. A 55-year-old man with a history of 4 years of hemodialysis therapy because of end-stage renal disease of unknown etiology underwent cadaveric renal transplantation in June 2006. Three days following the initiation of sirolimus therapy he complained of dry cough and fever. There were no clinical or laboratory findings compatible with specific pulmonary disease. After switching sirolimus to tacrolimus, the cough improved within 1-2 days and resolved in 5 days. Sirolimus should be considered in the differential diagnosis of pulmonary problems in the early posttransplantation period even in the absence of radiological findings.

Sirolimus-induced Alveolar Hemorrhage

Sirolimus is a well-known, potent immunosuppressant that is widely used in solid-organ transplantation, but it is not without potential side effects. A rare but devastating adverse effect is sirolimus-associated pulmonary toxicity. We report a case of sirolimus-induced diffuse alveolar hemorrhage confirmed by bronchoscopic findings (after other possible etiologies were ruled out) and by clinical and radiographic resolution of the pulmonary signs and symptoms a few days after sirolimus administration was stopped. This case and the existing literature on this topic suggest that sirolimus-induced pulmonary toxicity should be suspected in any patient taking immunosuppressants and who develops unexplained pulmonary symptoms.

Case Report of a Kidney Transplant Recipient Converted to Everolimus Due to Malignancy: Resolution of Bronchiolitis Obliterans Organizing Pneumonia Without Everolimus Discontinuation

The use of proliferative signal inhibitors (PSIs) in immunosuppression-related malignancies opens new roads for increasing the survival and quality of life in patients with solid organ transplantation. A 56-year-old female recipient of a living donor renal allograft (1990), who was immunosuppressed with cyclosporine (CsA; Neoral), azathioprine, and steroids, did initially well with acceptable renal function. During the last 5 years she required local therapy due to posterior vaginal lip human papillomavirus (HPV) lesions. In 2000, she discontinued azathioprine and the CsA doses were reduced to 100 mg daily. The local lesion showed a good response to reduced immunosuppression. In February 2005, the lesion reappeared and a biopsy showed malignancy. Local surgery was performed and CsA was replaced by everolimus (EVL; Certican). Two months after treatment initiation, the patient developed cough, dyspnea, and low-grade fever. Chest X-ray showed a lesion at the base of the left lung compatible with pneumonitis. After fiberbronchoscopy a diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP) was obtained. She was treated with increased doses of oral steroids. EVL was never discontinued. The radiological lesion disappeared and the malignancy is currently in remission. In summary, a case of gynecological cancer in a renal transplant recipient was treated by surgical removal. After 1 year of immunosuppression with EVL, no recurrence has been observed. The adverse event (BOOP) was probably related to the PSI treatment and was controlled with an increased dose of steroids without discontinuing EVL.

Pulmonary toxicity associated with sirolimus treatment in kidney transplantation

INTRODUCTION

An important side effect of sirolimus, a drug often used in organ transplantation, is pulmonary toxicity.

MATERIALS AND METHODS

We present five kidney transplant patients who developed this toxicity associated with sirolimus. All underwent chest radiography computed tomography, fiberoptic bronchoscopy with bronchoalveolar lavage (BAL), microbiological studies of the bronchial aspirate, blood, and sputum, and cytomegalovirus (CMV) polymerase chain reaction (PCR) in blood as well as two had transbronchial biopsies.

RESULTS

All five were men of mean age 54.8 +/- 10.3 years. In two sirolimus formed part of de novo therapy, and three were converted from calcineurin inhibitors. The mean treatment time was 16.6 +/- 13.7 months, with trough levels of 11.3 +/- 3 ng/mL. The patients presented with fever, cough, dyspnea, anemia, and dyslipidemia. The radiological pattern was diffuse alveolointerstitial (n = 2), or bilateral basal interstitial (n = 2), or bilateral basal alveolar (n = 1). The cell count in the BAL was 95% to 99% macrophages. In two patients cultures for bacteria were positive: Hemophilus and Pseudomonas. Tests for fungi, mycobacteria, pneumocystis, and legionella, as well as PCR for CMV were all negative. Transbronchial biopsy yielded insufficient material in one patient and a deposit of fibrinoid material and nonnecrotizing granuloma in the other. Antibacterial therapy was started, three with cotrimoxazole and two with ganciclovir, with no response. The respiratory symptoms improved after withdrawal of sirolimus (mean, 2.4 +/- 1.5 days). The mean hospital stay was 19.8 +/- 14.1 days.

CONCLUSION

Pulmonary toxicity due to sirolimus should be included in the differential diagnosis of kidney transplant patients who display signs of interstitial pneumonia. Its diagnosis is difficult requiring exclusion of other pulmonary diseases. Resolution of the symptoms was quick after suspension of the drug.

Pharmacologic approaches to composite tissue allograft

This article discusses the pharmacologic approaches and the most promising new compounds for composite tissue allograft tolerance. Although some approaches rely on a combination of immunosuppressive agents that act synergistically against rejection, other strategies use immunologic manipulation, including major histocompatibility complex matching, induction of chimerism, and use of monoclonal antibodies to abrogate the immune response. There is still a need, however, to reproduce these findings in species phylogenetically closer to humans. This may be the target of future research efforts, which may overcome the challenge of limb and face transplant rejection.

Toxicidad pulmonar asociada a sirolimus en el trasplante hepático

Sirolimus is a potent immunosuppressive drug that began to be used in the last few years. This drug was initially used in renal transplantation but its use in other solid organ transplantations such as liver, heart, lung and pancreas, has been increasing. Sirolimus is indicated in rescue therapies and to reduce the secondary toxic effects of calcineurin inhibitors. However, this drug has been associated with infrequent but severe pulmonary toxicity and cases of interstitial pneumonitis, bronchiolitis obliterans with organizing pneumonia, and alveolar proteinosis have been described. We present the case of a male liver transplant recipient who developed interstitial pneumonitis associated with sirolimus use.

Perioperative management of immunosuppression

Current immunosuppressive regimens typically consist of two phases: induction phase (medications given at the time of the initial transplant) and maintenance therapy. Induction medications are given to decrease the occurrence of early acute rejection, avoid or minimise corticosteroids, and potentially induce long-term favourable immunoregulatory effects. As tolerance remains an elusive goal, life-long maintenance immunosuppression is required after all solid-organ transplantations. The various agents used in these two phases of immunosuppression are reviewed in this article. The similarities and differences between the agents within each class, with respect to efficacy and tolerability, are discussed.

Resolution of sirolimus-induced pneumonitis after conversion to everolimus

BACKGROUND

Sirolimus-induced pneumonitis usually requires the complete cessation of sirolimus. Herein we have reported five cases of recovery from sirolimus pneumonitis after conversion from sirolimus to everolimus.

PATIENTS

All five cases were comparable with regard to their clinical conditions. The ages were between 46 and 64 years. They had received kidney transplants 3 to 18 years earlier. In four cases, the reason for sirolimus therapy was toxicity due to calcineurin inhibitors on a transplant biopsy; three of the patients also displayed malignant tumors: renal cell carcinoma, spinocellular carcinoma, or melanoma. Their serum creatinine levels were elevated between 150 and 350 micromol/L. In all five cases, bronchoscopy disclosed lymphocytic pneumonitis and bronchiolitis obliterans. The immunosuppressive co-medications were prednisolone in three, azathioprine in one, and mycophenolate mofetil in four cases. The previous sirolimus dose was 1 to 4 mg/day, with sirolimus trough levels between 5 and 12 ng/mL. The patients were switched to everolimus at doses between 1 x 0.25 and 2 x 0.75 mg/day to achieve trough concentrations between 3 and 8 ng/mL. Pulmonary symptoms and radiological findings resolved completely within 1 to 4 weeks.

CONCLUSION

Everolimus is more hydrophilic by virtue of differing from sirolimus by one hydroxyl group. Sirolimus-induced pneumonitis improved after conversion to everolimus.

Pneumopathie organisée au sirolimus : un diagnostic à évoquer chez le patient transplanté d'organe

INTRODUCTION

Sirolimus is a new immunosuppressive drug used in organ transplantation, particularly in renal transplantation. In the future, it could replace calcineurin inhibitors such as cyclosporine. It is currently associated with side effects, such as thrombocytopenia and hyperlipidemia. Several interstitial pneumonitis associated with sirolimus has been previously described in renal transplant recipients associated with marked general symptoms.

EXEGESIS

We report on a 65-year-old renal recipient presenting with a non typical case of sirolimus interstitial pneumonitis. He presented with fever and marked general symptoms for several months. CT scan showed a unilateral interstitial pneumonitis. After infectious, inflammatory and tumoral diseases were ruled out, sirolimus associated interstitial pneumonitis was evoked. The patient improved quickly after discontinuation of sirolimus.

CONCLUSION

It is important to evoke, after eliminating other aetiologies, sirolimus induced pneumonitis in face of an organ transplant recipient presenting with marked general symptoms even if the pulmonary symptoms are not predominant.

Sirolimus-associated interstitial pneumonitis in solid organ transplant recipients

Sirolimus is a potent immunosuppressive agent used with increasing frequency in solid organ transplantation (SOT). However, it has been associated with rare but devastating pulmonary toxicity. We describe a case of pulmonary toxicity associated with the use of sirolimus in a 64-yr-old heart transplant recipient. We also review all reported cases of sirolimus-associated lung toxicity among SOT recipients in an effort to better understand the pathophysiology, risk factors, and outcomes of this rare but serious complication. A total of 64 cases have been reported since January 2000 including the present case. These consisted of 52 kidney, four lung, three liver, three heart, one heart-lung and one islet cell transplants. In most cases, patients presented with a constellation of symptoms consisting of fever, dyspnea, fatigue, cough, and occasionally hemoptysis. Although the risk factors for this association have not been clearly established, high dose, late exposure to the drug and male gender have been noticed among most. In almost all of the reported cases, sirolimus was added later in the course of immunosuppressive therapy, usually in an effort to attenuate the nephrotoxic effects of a previous regimen containing a calcineurin inhibitor. There were three deaths (4.8%) among 62 patients with known status at follow up; all deaths were among heart transplant recipients. Most patients (95%) resolved their clinical and radiographic findings with discontinuation or dose-reduction of the drug. Sirolimus-induced pulmonary toxicity is a rare but serious entity that should be considered in the differential diagnosis of a transplant recipient presenting with respiratory compromise. Dose-reduction or discontinuation of the drug can be life saving.

Immunosuppressive agents in solid organ transplantation: Mechanisms of action and therapeutic efficacy

Effective immunosuppression is an essential pre-requisite for successful organ transplantation and improvements in outcome after transplantation have to a large extent been dependent on developments in immunosuppressive therapy. Here we provide an overview of the different immunosuppressive agents currently used in solid organ transplantation. A historical perspective on the development of immunosuppression for organ transplantation is followed by a review of the individual agents, with a focus on their mechanism of action and efficacy. Steroids, anti-proliferative agents (azathioprine and mycophenolate), calcineurin inhibitors (cyclosporine and tacrolimus) and TOR inhibitors (sirolimus and everolimus) are discussed along with both polyclonal and monoclonal antibody preparations. Many of the key clinical trials that underpin current clinical usage of these agents are described and side-effects of the different agents are highlighted. Finally, a number of newer agents still in various stages of clinical development are briefly considered.

Noninfectious Pulmonary Complications of Liver, Heart, and Kidney Transplantation

Because of their chronically immunosuppressed status, solid organ transplant recipients are continually at risk for infectious pulmonary complications. In addition, however, a number of noninfectious pulmonary complications plague the transplant recipient. These complications arise because of numerous factors, including the underlying conditions that preceded transplantation, the transplant surgery itself, and toxicity of post-transplantation medications. This article focuses on noninfectious pulmonary complications in the three largest recipient populations: liver, kidney, and heart.

What we CAN do about chronic allograft nephropathy: Role of immunosuppressive modulations

Given the potency of modern immunosuppressive agents, kidney transplantation across alloantingen barriers is a routine phenomenon with excellent 1-year graft survival in most centers. However, the improvement in 1-year graft survival has not been matched by improvements in long-term graft function and chronic allograft nephropathy (CAN) remains the second commonest cause of graft attrition over time. Calcineurin inhibitors, namely cyclosporine A (CyA) and tacrolimus, have been implicated as causal agents in the development of the fibrotic processes that are the hallmarks of CAN. Many studies have, therefore, concentrated on the improvement of long term graft function through the modulation of immunosuppressive therapy. It is the purpose of this review to describe and appraise the available evidence for the prevention and management of CAN through modulation of immunosuppressive agents.

Exogenous administration of immunomodulatory therapies in hematopoietic cell transplantation: an infectious diseases perspective

PURPOSE OF REVIEW

In contrast to the recipient of a solid organ transplantation, the immunological competence of recipients of hematopoietic cell transplantation does not correlate well with the administration of non-corticosteroid immunosuppressive agents. This apparent paradox reflects the unique and dynamic conglomeration of factors that affect immune reconstitution after hematopoietic cell transplantation. The following is the second part of a review of the recent primary literature regarding exogenous immunomodulatory influences as they pertain to infections in the setting of hematopoietic cell transplantation.

RECENT FINDINGS

The main themes of published primary research from 2004 to the present include the influence of exogenously administered immunomodulatory agents on infectious complications after hematopoietic cell transplantation.

SUMMARY

The use of immunomodulatory agents such as monoclonal antibodies directed against lymphocyte antigens in the treatment of hematopoietic malignancy has greatly expanded during the past decade. Separate trials of the potential utility of these agents, particularly in the reduction of graft-versus-host disease, in the setting of hematopoietic cell transplantation have yielded encouraging results. Given the infancy of these new approaches, it is not possible to make definitive statements regarding the relative risk of serious infection with each therapy. It is clear that a reduction in regimen-related non-infectious complications or mortality does not necessarily ensure a reduction in clinically significant infections. Improvements in early diagnostic and therapeutic options for these infections now bring us to an era of understanding pathogens such as cytomegalovirus as probes of the functional reconstitution of immunity.

Sirolimus for solid organ transplantation in children

Sirolimus represents a major advancement in the field of solid organ transplantation and is being used as a rescue agent for acute and chronic rejection as well as for primary immunosuppression with good graft outcome. Although initial studies with sirolimus were in adults, now significant data have accumulated on the role of sirolimus in pediatric solid organ transplantation. This article reviews the current status of sirolimus in pediatric transplantation.

BOOP is common in cardiac transplant recipients switched from a calcineurin inhibitor to sirolimus

While bronchiolitis obliterans organizing pneumonia (BOOP) has been associated with the use of sirolimus (SIR), the incidence in a consecutive group of patients given SIR to replace a calcineurin-inhibitor (CI) is unknown. Twenty-nine consecutive cardiac transplant recipients were switched from a CI to SIR to ameliorate CI-associated nephropathy or coronary graft atherosclerosis. Seven patients (24%) developed BOOP. The clinical characteristics and biopsy results of these patients are presented. The clinical course and response to withdrawal of SIR in all and steroids in four of seven patients suggested the diagnosis of BOOP. Chest X-rays and CT scans showed typical findings of BOOP in all seven patients. Infection was excluded in all patients. Biopsy results were characteristic of BOOP in six of seven patients. Six patients recovered and one died. BOOP is a common and potentially serious adverse event in cardiac transplant patients switched from a CI to SIR, especially when SIR is started late post-transplantation.

Low-dose mycophenolate mofetil is an effective and safe treatment to permit phased reduction in calcineurin inhibitors in chronic allograft nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN) is the most common cause of long-term renal-allograft dysfunction and the second most common cause of transplant loss. There are concerns that prolonged patient exposure to calcineurin inhibitors (CNIs) exacerbates or promotes the process of CAN.

METHODS

In our unit, we carried out an observational study over the period 2000 to 2003 using low-dose mycophenolate mofetil (MMF) to facilitate a phased reduction in the dose of CNI in a group of patients with CAN. Low doses of MMF were chosen to minimize adverse effects and to reduce levels of CNIs without the attendant risks of under-immunosuppression.

RESULTS

A step-wise reduction in mean reciprocalised creatinine was evident over the run-in period (mean 1/creatinine before MMF=0.005739-0.000083*month; R=0.77) with a step-wise monthly improvement postintroduction of MMF and dose reduction of CNI (mean 1/creatinine after MMF=0.004609+0.000049*month; R=0.74) (P<0.0001). The mean Cockroft-Gault estimated creatinine clearances were 47.1+/-24.2, 37.2+/-16.3, and 41.6+/-21.1 mL/min at time [t]=-12, t=0 and t=+12 months, respectively. Low-dose MMF therapy was well tolerated (only 7/89 patients stopped MMF because of side-effects in the first 12 months), and acute rejection was noted in only one patient. At latest follow-up, only 17 transplant losses had occurred, of which 6 patients had died with a functioning graft.

CONCLUSIONS

Low-dose MMF was well tolerated and resulted in prolonged graft survival.

Benefit-Risk Assessment of Sirolimus in Renal Transplantation

Sirolimus (rapamycin) is a macrocyclic lactone isolated from a strain of Streptomyces hygroscopicus that inhibits the mammalian target of rapamycin (mTOR)-mediated signal-transduction pathways, resulting in the arrest of cell cycle of various cell types, including T- and B-lymphocytes. Sirolimus has been demonstrated to prolong graft survival in various animal models of transplantation, ranging from rodents to primates for both heterotopic, as well as orthotopic organ grafting, bone marrow transplantation and islet cell grafting. In human clinical renal transplantation, sirolimus in combination with ciclosporin (cyclosporine) efficiently reduces the incidence of acute allograft rejection. Because of the synergistic effect of sirolimus on ciclosporin-induced nephrotoxicity, a prolonged combination of the two drugs inevitably leads to progressive irreversible renal allograft damage. Early elimination of calcineurin inhibitor therapy or complete avoidance of the latter by using sirolimus therapy is the optimal strategy for this drug. Prospective randomised phase II and III clinical studies have confirmed this approach, at least for recipients with a low to moderate immunological risk. For patients with a high immunological risk or recipients exposed to delayed graft function, sirolimus might not constitute the best therapeutic choice--despite its ability to enable calcineurin inhibitor sparing in the latter situation--because of its anti-proliferative effects on recovering renal tubular cells. Whether lower doses of sirolimus or a combination with a reduced dose of tacrolimus would be advantageous in these high risk situations remains to be determined. Clinically relevant adverse effects of sirolimus that require a specific therapeutic response or can potentially influence short- and long-term patient morbidity and mortality as well as graft survival include hypercholesterolaemia, hypertriglyceridaemia, infectious and non-infectious pneumonia, anaemia, lymphocele formation and impaired wound healing. These drug-related adverse effects are important determinants in the choice of a tailor-made immunosuppressive drug regimen that complies with the individual patient risk profile. Equally important in the latter decision is the lack of severe intrinsic nephrotoxicity associated with sirolimus and its advantageous effects on arterial hypertension, post-transplantation diabetes mellitus and esthetic changes induced by calcineurin inhibitors. Mild and transient thrombocytopenia, leukopenia, gastrointestinal adverse effects and mucosal ulcerations are all minor complications of sirolimus therapy that have less impact on the decision for choosing this drug as the basis for tailor-made immunosuppressive therapy. It is clear that sirolimus has gained a proper place in the present-day immunosuppressive armament used in renal transplantation and will contribute to the development of a tailor-made immunosuppressive therapy aimed at fulfilling the requirements outlined by the individual patient profile.

Pulmonary complications of solid organ and hematopoietic stem cell transplantation

The ability to successfully transplant solid organs and hematopoietic stem cells represents one of the landmark medical achievements of the twentieth century. Solid organ transplantation has emerged as the standard of care for select patients with severe vital organ dysfunction and hematopoietic stem cell transplantation has become an important treatment option for patients with a wide spectrum of nonmalignant and malignant hematologic disorders, genetic disorders, and solid tumors. Although advances in surgical techniques, immunosuppressive management, and prophylaxis and treatment of infectious diseases have made long-term survival an achievable goal, transplant recipients remain at high risk for developing a myriad of serious and often life-threatening complications. Paramount among these are pulmonary complications, which arise as a consequence of the immunosuppressed status of the recipient as well as from such factors as the initial surgical insult of organ transplantation, the chemotherapy and radiation conditioning regimens that precede hematopoietic stem cell transplantation, and alloimmune mechanisms mediating host-versus-graft and graft-versus-host responses. As the population of transplant recipients continues to grow and as their care progressively shifts from the university hospital to the community setting, knowledge of the pulmonary complications of transplantation is increasingly germane to the contemporary practice of pulmonary medicine.