Basiliximab

Introduction: Posttransplant lymphoproliferative disorder (PTLD) is a relatively infrequent but devastating complication that occurs after solid-organ transplantation. Although the optimal treatment for this condition is unknown, rituximab, a murine/human chimeric monoclonal antibody, has shown promise in the treatment of PTLD. In this report, we define the incidence, clinical features at presentation, and response to treatment of all cases of PTLD observed at our institution over a 10-year period, including four patients who received treatment with rituximab.

Methods: A review of all patients who underwent lung or heart-lung transplant at Duke University from 1992 to 2002 was performed (n = 400), and demographic and clinical outcome data were extracted.

Results: PTLD was observed in 10 of 400 patients (2.5%). Patients who acquired PTLD were predominately > 55 years old (8 of 10 patients) and with a native disease of COPD (7 of 10 patients). Diagnosis of PTLD was made a median of 343 days after transplant. The type of transplant and Epstein-Barr virus (EBV) status prior to transplant did not appear to influence the risk for PTLD. Patients presented with thoracic organ involvement (7 of 10 patients), extrapulmonary disease (2 of 10 patients), or both (1 of 10 patients). Histologic subtypes included polymorphic B cell (n = 4), monomorphic B cell (n = 3), B cell without further classification (n = 2), and anaplastic T cell (n = 1). Only one patient responded to reduced immunosuppression alone. Patients treated with surgery or radiation (n = 2) or rituximab (n = 4) had favorable responses to therapy. Both patients treated with chemotherapy died related to complications of treatment and PTLD.

Conclusions: Presentation and histologic appearance of PTLD varies considerably among lung transplant recipients. PTLD was more frequent among older patients with COPD, regardless of pretransplant EBV serology. Rituximab appears effective as a first-line therapy for PTLD, but additional studies are needed in order to define its efficacy and side effect profile in this population of patients.

Key words: anti-CD20 monoclonal antibody; heart-lung transplant; lung transplant; posttransplant lymphoproliferative disorder; rituximab

Abbreviations: CHOP = cytoxan, adriamycin, vincristine, and rednisone; EBNA = Epstein-Barr virus nuclear antigen; EBV = Epstein-Barr virus; FDG-PET = F-18 fluorodeoxyglucose-positron emission tomography; LMP = latent membrane protein; PTLD = posttransplant lymphoproliferative disorder

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Posttransplant lymphoproliferative disorder (PTLD) is a relatively infrequent but devastating complication that occurs after solid-organ transplantation. The reported incidence of PTLD in lung transplant recipients varies between 1.8% and 20%. (1-5) PTLD is a histologically heterogeneous disease that varies from a cytologically benign polyclonal lymphoid proliferation to a monoclonal proliferation with features of frank lymphoma. Most cases are of B-cell origin. A major risk factor for the development of PTLD is thought to be EBV-negative serology prior to transplantation and EBV seroconversion after transplantation. (2,6) Aggressive immunosuppression regimens are also thought to play an etiologic role, particularly the use of induction agents at the time of transplantation (7); however, knowledge of the clinical, radiographic, and histologic patterns of PTLD in lung transplant recipients remains limited.

Due to the morphologic spectrum of PTLD and its rare occurrence, determination of the best treatment modality has been challenging. Historically, the treatment of PTLD has been decreased immunosuppression alone or in combination with other treatment options, including surgical resection, antiviral agents, radiation, and chemotherapy. Standard chemotherapy treatments, however, can result in significant morbidity in transplant populations due to myelosuppression and sepsis, resulting in poor long-term outcomes. (8) Rituximab, a murine/human chimeric monoclonal antibody specific for CD20, a cell-surface molecule primarily expressed by B cells, has shown promise in the treatment of PTLD in kidney and liver transplant recipients. (9,10) Experience in lung transplant recipients, however, is limited. (11,12) In this report, we retrospectively reviewed all cases of PTLD in 400 consecutive lung or heart-lung transplant recipients at our institution in order to better define the clinical, radiographic, and histologie features of this disorder. In addition, we sought to determine if outcomes were improved in those patients treated with rituximab, as compared to more conventional chemotherapy and/or radiation.

MATERIALS AND METHODS

We performed a retrospective review of all lung and heart-lung transplant recipients with a diagnosis of PTLD since the inception of our lung transplant program in 1992. Of a total of 400 lung of heart-lung transplant recipients who underwent transplantation from 1992 until July 1, 2002, 10 patients received a diagnosis of PTLD. The demographic information for these patients is shown in Table 1; the data were obtained by medical record review.

Patients who acquired PTLD received postoperative immunosuppression with cyclosporine A (5 to 10 mg/kg/d) [n = 6] or tacrolimus (0.05 to 0.1 mg/kg/d) [n = 4], azathioprine (1 to 2 mg/kg/d), and corticosteroids (methylprednisolone, 125 mg q12h for the first 48 h, followed by prednisone, 20 mg/d). Prednisone was tapered to 5 mg/d over the following year. One patient received induction immunosuppression with rabbit antithymocyte globulin, and four patients received a monoclonal interleukin-2 receptor antibody (daclizumab or basiliximab) as induction immunosuppression. Patients who underwent transplantation during the study period who did not acquire PTLD received similar immunosuppressive combinations. Episodes of acute allograft rejection were treated with methylprednisolone, 500 mg/d for 3 days, followed by a 2 week oral prednisone taper.

All patients at risk for cytomegalovirus infection (positive donor of recipient serology) received prophylaxis with at least 4 weeks of IV ganciclovir. All patient received Pneumocystis carinii prophylaxis indefinitely. Patients also received aerosolized amphotericin B (either liposomal or conventional) for at least 2 weeks after transplant for antifungal prophylaxis. (13) Vancomycin and ceftazidime were used for bacterial infection prophylaxis during the first 2 weeks after transplant, except in patients with septic lung disease, where antibiotic choice was guided by pretransplant culture findings. Each cycle of rituximab was 375 mg/[m.sup.2] per dose administered IV weekly for 4 weeks.

At time of presentation with PTLD, 9 of 10 patients underwent diagnostic CT of the chest. Four of 10 patients also underwent CT of the abdomen and pelvis performed as part of their staging evaluation. F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) was performed in four patients, [sup.67]Ga scintigraphy was performed in four patients, and CT of the neck was performed in two patients. One patient, whose lymphoma was discovered at autopsy, did not undergo staging evaluation. All radiologic studies were reviewed by an experienced thoracic radiologist (H.P.M.).

Histopathologic examination of tissue from all patients confirmed the diagnosis of PTLD; all cases were reviewed by an experienced pathologist (D.N.H.). Diagnoses were made based on biopsy findings in nine patients (lung biopsy in seven patients, tongue and duodenal biopsies in one patient, and supraclavicular lymph node biopsy in one patient). Of the seven lung biopsies showing PTLD, taro were transbronchial biopsies and five were thoracoscopic wedge biopsies. For patient 10, the recipient of a single lung transplant for COPD, a diagnosis of PTLD involving both the transplanted and native lung was established at autopsy.

In most cases, deseriptive statistics were used. In eases of comparisons between PTLD and non-PTLD lung recipients, the Fisher exact test, [chi square] analysis, of two-tailed t testing was performed, as appropriate.

RESULTS

The most common indications for transplant in our population were as follows: COPD (50%), cystic fibrosis (25%), pulmonary fibrosis (14%), and sarcoidosis (5%). Demographic information, treatment regimens and outcomes are shown in Table 2. The mean ([+ or -] SD) age of our patients with PTLD was 53.8 [+ or -] 15.4 years, and 80% were > 55 years old. In contrast, only 39% (152 of 390 transplant recipients) without PTLD were > 55 years old (p = 0.02, Fisher exact test). There was a trend toward more transplants for COPD in the patients with PTLD (70%), as compared to remainder of the population (49%; p = 0.20, Fisher exact test). In contrast, patients who acquired PTLD were not significantly different than the remainder of the population in terms of type of transplant operation or induction/ maintenance immunosuppression regimens. Although incomplete Epstein-Barr virus (EBV) serologic data were available on the population, the development of PTLD did not appear clearly associated with negative EBV serologic findings in our population, as at least five patients with positive serologic findings acquired PTLD (Table 2).

The mean duration from transplantation to the diagnosis of PTLD was 339 days (median, 343 days; range, 113 to 800 days). Radiologic findings at presentation are summarized in Table 3. Seven patients had PTLD confined to their allograft. In these cases, PTLD manifested on chest radiographs or CT as solitary lung mass or nodule in four patients, as multiple masses or nodules in two patients, and as a hilar mass in one patient. Three of the 10 patients presented with disseminated disease.

Histopathologic and immunohistochemical findings are shown in Table 4. hi nine patients, the proliferating cells were of the B-lymphocytic lineage. This was assessed by immunoperoxidase staining with antibody against the pan-B-cell antigen CD20 and supplemented in some eases with staining for other B-cell-specific markers. In these nine cases, positive immunostaining was documented for EBV nuclear antigen (EBNA)-2 (Fig 1, top left, A), and staining for latent membrane protein (LMP) [Fig 1, top right, B] was present in all except patient 1. The tumor of patient 6 stained for CD30, as well as the pan-T-cell marker CD3, and was classified as an anaplastic large cell (Ki-1) lymphoma. Staining for EBNA-2 and LMP was negative for patient 6.

[FIGURE 1 OMITTED]

Of the nine eases of B-lymphocytic PTLD, four eases were classified as polymorphic (Fig 1, bottom left, C) and three eases were classified as monomorphic/large B-cell lymphoma (Fig 1, bottom right, D) based on histologic criteria. (14) Insufficient viable tissue was available for subclassification for patient 1 and patient 8. Information on clonality was available in four cases. Flow cytometry identified monoclonal (light chain positive B cell) populations in two eases (patient 2 and patient 4). Ig gene rearrangement studies in two additional cases (patient 5 and patient 9) showed a clonal rearrangement. Flow cytometry was performed in one additional ease (patient 3), but was inconclusive. Thus, four patients had definite monoclonal PTLD.

[FIGURE 1 OMITTED]

Treatment

For the treatment of PTLD, all patients received reduced immunosuppression. Some patients received antiviral. prophylaxis with IV or oral ganciclovir. Two patients received multiple cycles of cytoxan, adriamycin, vincristine, and prednisone (CHOP). CHOP therapy was unsuccessful in one of the two patients treated with chemotherapy, and this patient received three cycles of rescue therapy with mesna, ifosfamide, mitoxantrone, and etoposide. Treatment was unsuccessful in both patients who received chemotherapy, and they died of sepsis complicated by refractory PTLD. Patient 7 and patient 8, who received only radiation and surgical resection, respectively, in addition to reduced immunosuppression, did not have a recurrence of PTLD. Patient 5 received only reduced immunosuppression without recurrence of PTLD.

Four patients received treatment with rituximab. All had B-cell PTLD. PTLD was diagnosed in patient 1 when chest CT revealed a lobulated 5-cm left lower lobe mass (Fig 2, top), intensely hypermetabolic on FDG-PET imaging. Transbronchial biopsy confirmed the diagnosis of an EBV-associated, CD20+, B-cell lymphoma. Staging evaluation showed no other sites of disease. A follow-up chest CT obtained 2 months after the first cycle of rituximab therapy showed a reduction in the size of the left lower lobe mass to 2 cm. A follow-up chest CT (Fig 2, bottom) 2 months after a second cycle of rituximab showed only a residual sear in the left lower lobe. Follow-up FDG-PET performed the same day showed no increased metabolic activity in the residual nodule.

[FIGURE 2 OMITTED]

Disseminated PTLD was diagnosed in patient 2. Chest, abdomen, and pelvis CT showed multiple lung nodules, as well as multiple low-attenuation lesions in the liver and small-bowel wall thickening. Follow-up CT 1 month after the completion of the first cycle of rituximab demonstrated marked improvement in the size and number of lung lesions, as well as resolution of the liver lesions and bowel wall thickening. The most recent follow-up lung biopsy, 9 months following the diagnosis of PTLD and after a second cycle of rituximab, showed no evidence of residual disease.

Patient 3 had a right lower lobe mass and multiple bilateral lung nodules on chest CT (Fig 3, top). FDG-PET imaging showed multiple foci of hyper-metabolism in the lungs corresponding to the nodules and masses, but no evidence of extrathoracic disease. Follow-up CT 1 month after the completion of the first cycle of rituximab therapy showed decreased size and number of lung nodules. Chest CT, 6 months following the diagnosis of PTLD and a second cycle of rituximab, demonstrated almost complete resolution of the nodules (Fig 3, bottom). Follow-up lung biopsies have shown no evidence of residual PTLD.

[FIGURE 3 OMITTED]

Patient 4 presented with a mass in the neck and left tongue base. CT of the chest, abdomen, and pelvis showed diffuse small-bowel wall thickening without evidence of intrathoracic disease. Four cycles of rituximab were administered because of a limited response to the initial treatment and the disseminated nature of disease. In the months that followed, multiple infectious complications developed, including viral pneumonia, fungal liver abscess, recurrent ileus, and small-bowel obstruction. The patient became increasingly malnourished and dependent on total parenteral nutrition, and ultimately died of bacterial and fungal sepsis 371 days after the initial diagnosis of PTLD. Radiographic studies demonstrated no obvious signs of recurrent disease, and a portion of small bowel resected 8 months after the initial diagnosis showed ulceration and necrosis, but no evidence of residual tumor. No other patients had any infectious or other complications after treatment with rituximab.

DISCUSSION

Our results demonstrate a low incidence of PTLD in a large cohort of lung transplant recipients. Patients with PTLD tended to be > 55 years old and with a native disease of COPD; PTLD in our population appeared unrelated to pretransplant EBV status of immunosuppressive regimen. Presentation with single or multiple nodules of masses in the thorax was most common, although extrapulmonary, disease was seen in a few patients. Most patients had histologic evidence of monomorphic or polymorphic B-cell PTLD, although one case of anaplastic T-cell lymphoma was observed.

The reported incidence of PTLD in lung transplant recipients ranges from 1.8 to 20%. At our institution, l0 of 400 lung or heart-lung transplant recipients (2.5%) have received a diagnosis of PTLD, a low percentage despite our aggressive approach to immunosuppression. Our results, however, are consistent with a recent report by Levine and colleagues (1) who also found a low incidence of PTLD at their institution, 1.8% (2 of 109 patients). Variability in the incidence of PTLD may reflect differences in immunosuppression protocols, age of the population studied, rates of primary EBV infections, and cytomegalovirus prophylaxis. For example, among our population of 400 lung or heart-lung recipients, there were very few adolescent EBV-naive patients. Some have suggested that the routine use of ganciclovir prophylaxis after lung transplant has favorably influenced rates of posttransplant lymphoma. (1)

Several clinical, radiographic, and histologic features at presentation appear to influence the prognosis in lung transplant recipients with PTLD. (15,16) PTLD was diagnosed in most patients in our study within the first year after transplantation; time to diagnosis of PTLD ranged from 113 to 800 days. The significance of early vs late onset of PTLD was examined by Paranjothi and colleagues, (15) who identified PTLD in 30 of their recipients over 1,687 patient-years (6.1% incidence). More patients were identified in the first year following transplant, as compared to later years, consistent with our results. Although early vs late presentation was not a significant factor in prognosis, early patients tended have disease confined to the allograft. In that series, PTLD confined to the allograft was associated with improved survival as compared to disseminated disease.

The radiographic pattern of disease at presentation is associated with different outcomes in PTLD after lung transplant. In one series, the finding of a solitary pulmonary nodule was associated with a more favorable course, as compared to other radiographic patterns, such as multiple nodules or hilar/ mediastinal adenopathy (1-year survival of 89% vs 35%, respectively. (17)

The histologic pattern of disease at diagnosis is also thought to influence prognosis. Prognosis is generally worse in patients with monoclonal, monomorphic B-cell lymphoma. However, in a series (18) from the Cleveland Clinic, patients did equally poorly with monomorphic vs polymorphic disease, suggesting that a subset of polyclonal lesions can have a more aggressive course.

Treatment options for PTLD include reduced immunosuppression, surgical resection, radiation, and chemotherapy. In our series, only one patient responded to reduced immunosuppression alone, and two patients had favorable responses following resection and/or radiation and reduction in immunosuppression. In contrast, the two patients who received chemotherapy were considered treatment failures and experienced considerable toxicities. Toxicities secondary to chemotherapy for the treatment of PTLD are reported elsewhere in the literature. (8) Swinnen et al (8) reported sepsis and cardiac toxicity in a series of heart transplant recipients who received prednisone, doxorubicin, cyclophosphamide, and etoposide followed by cytarabine, bleomycin, vincristine, methotrexate, and leucovorin.

Concerns with toxicities associated with chemotherapy in the treatment of PTLD have led to interest in less toxic alternative treatments. Immunotherapy offers a more attractive therapeutic option in transplant patients who are already plagued by infections and renal insufficiency. Rituximab is a chimeric murine/human monoclonal antibody directed against the CD20 antigen. The exact mechanism by which it eliminates tumor cells in vivo is not completely understood, but it is thought to involve antibody-dependent cell-mediated cytotoxicity, as well as complement-mediated cytotoxicity and induction of apoptosis. (19)

In 1999, Cook et al (11) reported successful regression of PTLD in two of three lung transplant recipients with progressive, treatment-refractory PTLD after treatment with standard doses of rituximab over 4 weeks. Most recently, Verschuuren et al (12) reported their experience with the use of rituximab in three patients. One of the three patients treated with rituximab is in complete remission 16 months after rituximab treatment (375 mg/[m.sub.2] per dose on days 7, 14, 21, and 28). A second patient relapsed after 2 months with a partly CD-20-negative PTLD, and another patient died of infections complications. (20)

In our analysis, four patients received treatment with rituximab. All of the rituximab-treated patients had regression of disease. Three of the four patients appear to be cured. Our findings are particularly striking considering some had evidence for extrapulmonary organ involvement (patient 2 and patient 4), multiple nodules (patient 2 and patient 3), and monoclonality on flow cytometry (patient 2 and patient 4)--findings typically associated with poor prognosis and limited survival. Our data suggest that rituximab is a reasonable first-line therapy in the treatment of PTLD in lung recipients regardless of clinical, radiographic, or histologic findings at presentation.

Although there have been reports of hypogammaglobulinemia and multiple fungal and viral infections in organ transplant recipients treated with rituximab, only one of our four patients experienced any infectious complications; in addition, that patient had malnutrition requiring total parenteral nutrition (12,20-22) Furthermore, that patient received a higher total dose of therapy (through four cycles) because of concern for progressive disease contributing to GI obstruction. Ultimately, bowel histology demonstrated no residual GI disease. Previous reports (21,22) make the true incidence of infectious complications with rituximab alone difficult to define because of concurrent chemotherapy.

In conclusion, PTLD should be considered in any lung transplant recipient who presents with one or more pulmonary nodules, regardless of age or EBV serology. Although the optimal treatment of PTLD after lung transplant is unknown, our experience adds to the current literature and suggests that rituximab may be at least as effective as other approaches. This may be particularly true in patients at high risk for a poor outcome, such as those with disseminated or monoclonal disease at presentation. Additional prospective research is needed to better define the role of rituximab in the treatment of PTLD, as well as to determine complications that may be specific to lung transplant patients. Identification of patients most likely to respond to specific treatments based on clinical and/or histologic features of the disease should be a major focus of future research.

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* From the Departments of Pharmacy (Dr. Reams), Radiology (Dr. McAdams), and Pathology (Dr. Howell); Division of Pulmonary and Critical Care Medicine (Drs. Steele and Palmer), Department of Medicine; and Division of Cardiothoracic Surgery (Dr. Davis), Department of Surgery, Duke University Medical Center, Durham, NC.

Manuscript received November 26, 2002; revision accepted March 27, 2003.

Correspondence to: Scott M. Palmer, MD, MHS, FCCP, Medical Director, Lung Transplantation Program, Box 3876, Duke University Medical Center, Durham, NC 27710; e-mail: Palme002@mc.duke.edu

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