The role of adoptive immunotherapy in the prevention and treatment of lymphoproliferative disease following transplantation

Generation of Epstein-Barr virus-specific cytotoxic T lymphocytes resistant to the immunosuppressive drug tacrolimus (FK506)

Adoptive transfer of autologous Epstein-Barr virus-specific cytotoxic T lymphocytes (EBV-CTLs) to solid organ transplant (SOT) recipients has been shown safe and effective for the treatment of EBV-associated posttransplantation lymphoproliferative disorders (PTLDs). SOT recipients, however, require the continuous administration of immunosuppressive drugs to prevent graft rejection, and these agents may significantly limit the long-term persistence of transferred EBV-CTLs, precluding their use as prophylaxis. Tacrolimus (FK506) is one of the most widely used immunosuppressive agents in SOT recipients, and its immunosuppressive effects are largely dependent on its interaction with the 12-kDa FK506-binding protein (FKBP12). We have knocked down the expression of FKBP12 in EBV-CTLs using a specific small interfering RNA (siRNA) stably expressed from a retroviral vector and found that FKBP12-silenced EBV-CTLs are FK506 resistant. These cells continue to expand in the presence of the drug without measurable impairment of their antigen specificity or cytotoxic activity. We confirmed their FK506 resistance and anti-PTLD activity in vivo using a xenogenic mouse model, suggesting that the proposed strategy may be of value to enhance EBV-specific immune surveillance in patients at high risk of PTLD after transplantation.

Ex vivo generation of cytokine-induced killer cells (CD3+ CD56+) from post-stem cell transplant pediatric patients against autologous-Epstein-Barr virus-transformed lymphoblastoid cell lines

EBV-PTLDs affect as high as 20% of SCT recipients especially those with T-cell depleted grafts while high mortality rates were also noted. Adoptive allogeneic and autologous CTLs have a therapeutic potential in this setting. However, the process of expansion of these cells is tedious and time consuming in both allogeneic and autologous CTL generation. For the allogeneic SCT, another major obstacle is unavailability of donors especially in an unrelated SCT setting. The aim of the present study was therefore to investigate the efficacy of autologous CIK cells (CD3+ CD56+) against autologous EBV-LCLs from post-SCT pediatric patients. We could demonstrate that CIK cells can be generated within two wk and did show the significant cytotoxicity against autologous EBV-LCLs. CIK cells may provide a potent tool for use in post-transplantation adoptive immunotherapy.

Posttransplant lymphoproliferative disorder of the lung in a renal transplant recipient treated successfully with surgery

Posttransplant lymphoproliferative disorders (PTLDs) are a heterogeneous group of lymphoid diseases that occur after solid organ and bone marrow transplantation. Lung-located PTLD has been reported in recipients of the heart, cord blood stem cells, lungs, and bone marrow transplants, but only four cases were reported previously after kidney transplantation. Thoracic location of PTLD must be regarded as an especially dangerous complication. The pathogenesis, and clinical and histological features of PTLD remain poorly defined but predisposing risk factors are becoming better understood. Namely, Epstein-Barr virus (EBV) and immunosuppressive agents appear to be such risk factors. There has been marginal success in treating PTLD using a number of treatment modalities, including combination chemotherapy with anti-CD20 or high-dose chemotherapy with stem cell rescue. We report a renal allograft recipient transplanted in March 2000, diagnosed with EBV-associated and lung-located PTLD. His initial immunosuppression consisted of tacrolimus, azathioprine, and steroids. Azathioprine was withdrawn in September 2001. In November 2001 a high-resolution computed tomography scan revealed two round masses in the right lung. The patient underwent right thoracotomy and resection of the lower and middle lobe. The diagnosis of PTLD was settled by intraoperative histopathological evaluation. The postoperative histological assessment confirmed the diagnosis and revealed positive staining for EBV. The patient remained in complete remission for 3 years with a well-functioning renal allograft, with current serum creatinine of 1.2 mg%. This case illustrates that the treatment of lung-located PTLD may be successful, but it depends on a combination of prompt diagnosis, reduction of immunosuppression, and of course surgery.

Epstein-Barr virus associated post-transplantation lymphoproliferative disorder with hemophagocytosis in a child with Wiskott-Aldrich syndrome

A 23-month-old boy with Wiskott-Aldrich syndrome (WAS) received human leukocyte antigen (HLA)-one locus mismatched, unmanipulated allogeneic bone marrow graft from his mother. An Epstein-Barr virus (EBV)-associated post-transplantation lymphoproliferative disorder (PTLD) of donor cell origin and hemophagocytosis syndrome with fever, lymphadenopathy, hepatosplenomegaly, seizures, involuntary movements and pancytopenia developed 52 days after transplantation. It was difficult to decide on the treatment strategy because the patient presented with B-cell hyperplasia that morphologically appeared malignant but was oligoclonal by heavy-chain analyses. Despite of donor leukocyte transfusion, low dose chemotherapy, and anti-B cell monoclonal antibody immunotherapy, the patient died 107 days after transplantation.

Viral prophylaxis in organ transplant patients

Viral pathogens have emerged as the most important microbial agents having deleterious effects on solid organ transplant (SOT) recipients. Antiviral chemoprophylaxis involves the administration of medications to abort transmission of, avoid reactivation of, or prevent progression to disease from, active viral infection. Cytomegalovirus (CMV) is the major microbial pathogen having a negative effect on SOT recipients. CMV causes infectious disease syndromes, augments iatrogenic immunosuppression and is commonly associated with opportunistic superinfection. CMV has also been implicated in the pathogenesis of rejection. Chemoprophylactic regimens for CMV have included oral aciclovir (acyclovir) at medium and high doses, intravenous and oral ganciclovir, and the prodrugs valaciclovir (valacyclovir) and valganciclovir. CMV prophylactic strategies should be stratified, with the highest-risk patients receiving the most 'potent' prophylactic regimens. Herpes simplex virus (HSV) reactivation in SOT recipients is more frequent, may become more invasive, takes longer to heal, and has greater potential for dissemination to visceral organs than it does in the immunocompetent host. Prophylactic regimens for CMV are also effective chemoprophylaxis against HSV; in the absence of CMV prophylaxis, aciclovir, valaciclovir or famciclovir should be used as HSV prophylaxis in seropositive recipients. Primary varicella-zoster virus (VZV) after SOT is rare and most commonly seen in the paediatric transplant population because of VZV epidemiology. Zoster occurs in 5-15% of patients, usually after the sixth post-transplant month. Prophylactic regimens for zoster are neither practical nor cost effective after SOT because of the late onset of disease and low proportion of affected individuals. All SOT recipients should receive VZV immune globulin after contact with either varicella or zoster. Epstein-Barr virus has its most significant effect in SOT as the precipitating factor in the development of post-transplant lymphoproliferative disorders. Antiviral agents that could be effective are the same as those used for CMV, but indications for and effectiveness of prophylaxis are poorly established. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are important pathogens in the SOT population as indications for transplantation. So-called 'prophylaxis' for recurrent HBV and HCV after liver transplantation is controversial, suppressive rather than preventive, and potentially lifelong. Influenza infection after SOT is acquired by person-to-person contact. During epidemic periods of influenza, transplant populations experience a relatively high frequency of infection, and influenza may affect immunosuppressed SOT recipients more adversely than immunocompetent individuals. Antiviral medications for prevention of influenza are administered as post-exposure prophylaxis to SOT recipients, in addition to yearly vaccine, in circumstances such as influenza epidemics and nosocomial outbreaks, and after exposure to a symptomatic individual during 'flu season'.

Viruses and tumours--an update

In the 40 years since the publication of the article by Harris (Eur J Cancer 1965, 1, 183-188), considerable progress has been made towards the understanding of the contribution of infectious agents to the development of tumours. It is estimated that 15-20% of human malignancies may have an infectious aetiology. This article attempts to summarise the current level of our knowledge with respect to tumour-associated viruses, and to place this in the context of the earlier article by Harris (Eur J Cancer 1965, 1, 183-188).

Establishment and characterization of a bank of cytotoxic T lymphocytes for immunotherapy of epstein-barr virus-associated diseases

Adoptive immunotherapy using Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTL) generated ex vivo can be an effective treatment of EBV-positive posttransplantation lymphoproliferative disease (PTLD). We describe the establishment of a cryopreserved repository of allogeneic virus-specific CTL lines, to our knowledge the first of its kind in the world. CTL lines were grown by weekly stimulation with autologous EBV immortalized lymphoblastoid cell lines (LCLs) from 96 EBV-seropositive blood donors. Analysis of 60 CTL lines grown continuously for 7 to 10 weeks showed an average proportional weekly increase in cell numbers of 1.4, with an overall increase ranging from 1.1 to 83.4. The greatest increase occurred during the early culture period. After four rounds of stimulation, killing of autologous LCLs was generally high (mean 48%); however, most lines required 9 or 10 stimulations to reduce the killing of nonspecific targets. Overall, 79% of CTLs generated showed acceptable levels of specific killing. Phenotypically, the CTL lines consisted of TCRalpha beta+, CD8+ T cells (medians 97% and 90% respectively) with a minority population of CD4+ T cells (median 2%). Most cells expressed the activation and differentiation markers, HLA-DR, CD26, CD45RO, CD69, and CD150. Favorable results have been obtained in an open trial using partially HLA-matched, allogeneic CTLs from this bank to treat PTLD patients. This now represents a single resource that can provide therapeutic CTLs rapidly on a countrywide basis, superseding the time-consuming, expensive practice of generating autologous CTLs from each patient requiring treatment. Additionally, other patient groups, such as those with EBV-positive Hodgkin disease, may benefit from CTL treatment.

Adoptive T-cell therapy for EBV-associated post-transplant lymphoproliferative disease

Increased understanding of the mechanisms by which T lymphocytes recognize virus and tumor-specific antigens has fueled the use of adoptive immunotherapy for viral and malignant diseases. An ideal candidate for such treatment is Epstein-Barr virus (EBV). EBV-associated post-transplant lymphoproliferative disorder (PTLD) is a serious complication post-solid organ transplant (SOT) or hematopoietic stem cell transplant (HSCT). The disease is essentially the result of suppression of cytotoxic T-cell function and despite various treatment strategies the course may still be fulminant and lethal. Therefore, an adoptive immunotherapeutic approach using ex vivo derived EBV-specific CTL offers a promising solution not only for the treatment but also as prophylaxis for PTLD. The infusion of EBV-CTL has been demonstrated to be safe and effective in allogeneic HSCT recipients and their use post-SOT is being evaluated.

Epstein-Barr virus (EBV) load and interleukin-10 in EBV-positive and EBV-negative post-transplant lymphoproliferative disorders

Post-transplant lymphoproliferative disorders (PTLDs) are heterogeneous severe complications occurring in 1-10% of transplanted patients. In most cases, PTLDs are associated with Epstein-Barr virus (EBV) infection but, recently, some clinical studies have reported an increasing number of EBV-negative PTLDs. Several studies have emphasized the critical role of the early identification of patients at risk for PTLD, in prompting the adoption of either pre-emptive strategies or timely treatment. To this purpose, monitoring of EBV DNA load in peripheral blood mononuclear cells is considered to be a useful test. Moreover, recently, the role of interleukin (IL)-10 in EBV-related diseases has been remarked, and high levels of IL-10 have been detected in PTLD patients. In this study, both EBV load and IL-10 were monitored in 38 PTLD patients at diagnosis and during follow-up, as well as in a control group, in order to establish the diagnostic role of the two tests, their relationship with the different PTLD subsets (EBV-positive and EBV-negative) and their behaviour during treatment. Results of our study suggest that the usefulness of IL-10 assay for early diagnosis of PTLD is similar to that of EBV load quantification, and its clinical diagnostic value is lower in EBV-negative than in EBV-positive PTLDs.

Risk of lymphoid neoplasia after cardiothoracic transplantation: the influence of underlying disease and human leukocyte antigen type and matching

BACKGROUND

It has been known for more than 20 years that there is an increased risk of lymphoid neoplasia after cardiothoracic transplantation. Recent studies have demonstrated the importance of primary Epstein-Barr virus (EBV) infection and type of immunosuppressive therapy to the cause of these neoplasms, but the contribution of other factors remains equivocal.

METHODS

The authors followed 1,562 patients undergoing cardiothoracic transplantation at Harefield Hospital, United Kingdom, and used standard cohort methods of analysis to examine whether posttransplant lymphoma risk was related to the underlying disease requiring transplantation or the human leukocyte antigen (HLA) type and matching. Lymphomas were categorized into EBV-associated lymphoproliferative disease (LPD) and EBV-negative non-Hodgkin's lymphoma (NHL), and the authors carried out separate analyses of these.

RESULTS

The authors found no significant association between the underlying disease necessitating transplantation and the risk of lymphoid neoplasia. There was also no evidence of a relation of lymphoma risk with the presence or absence of any particular HLA antigen, although significant protective effects of HLA-B14 and -B57 were found when analyses were conducted without adjustment for multiple testing. Risk of LPD was not associated with degree of HLA mismatching, but there was a significant effect of mismatching on risk of EBV-negative tumors.

CONCLUSIONS

The differential effect of HLA mismatching on the risks of LPD and EBV-negative NHL provides further evidence that these two tumors are distinct etiologic entities. The authors' results suggest that the immunologic cause of EBV-negative NHL may be different from that of LPD. Investigation of the relation of risk of EBV-negative NHL to degree of immunosuppression is needed.

Treatment of Epstein-Barr-virus-positive post-transplantation lymphoproliferative disease with partly HLA-matched allogeneic cytotoxic T cells

BACKGROUND

Epstein-Barr virus (EBV)-associated post-transplantation lymphoproliferative disease (PTLD) is a common, often fatal, complication of bone-marrow and solid-organ transplantation. Since tumour growth results from inadequate T-cell control of latent EBV, new immunotherapeutic approaches to treatment are being pioneered.

METHODS

In a phase 1/2 trial, eight patients with progressive PTLD unresponsive to conventional treatment were given one to six infusions of partly HLA-matched allogeneic EBV-specific cytotoxic T lymphocytes (CTLs) from a frozen bank of CTLs derived from healthy blood donors.

FINDINGS

Of the five patients who completed treatment, three had complete remission and two had no clinical response. One patient partly responded after two infusions. No graft-versus-host disease or allo-specific antibodies were detected, and graft function improved in three cases. Tumour responses were mainly seen in those with early, localised, polyclonal disease. EBV load in peripheral blood fell to undetectable levels in all patients who responded to treatment, but was more variable in those who did not.

INTERPRETATION

Treatment of EBV-associated PTLD with partly HLA-matched CTLs grown from unrelated donors is effective. Spontaneous remission is very unlikely to account for tumour regression in our patients; however, a larger, controlled trial is needed to assess this treatment further. The frozen bank of allogeneic CTLs is less prohibitively labour intensive and expensive for wide scale use than treatment with autologous CTLs. Such banks could be established to treat other infectious and neoplastic diseases in many patients.

Identification and prevalence of CD8(+) T-cell responses directed against Epstein-Barr virus-encoded latent membrane protein 1 and latent membrane protein 2

Epstein-Barr virus (EBV) is associated with several human malignancies that each show different viral gene expression profiles. In malignancies such as Hodgkin's disease and nasopharyngeal carcinoma only Epstein-Barr nuclear antigen 1 (EBNA1) and varying levels of latent membrane proteins 1 and 2 (LMP1 and -2) are expressed. Since endogenously expressed EBNA1 is protected from CTL recognition, LMP1 and LMP2 are the most likely target antigens for anti-tumor immunotherapy. Therefore, we sought to identify in a systematic way CD8(+) T-cell responses directed against eptitopes derived from LMP1 and LMP2. Using IFNgamma-ELISPOT assays of interferon-gamma release, peripheral blood mononuclear cells (PBMC) of healthy donors were screened with peptide panels (15 mer overlapping by 10) spanning the LMP1 and LMP2 sequences of the prototype EBV strain B95.8. When positive responses were found, CD4(+) or CD8(+) T cells were depleted from donor PBMC to determine the origin of the responder population. We detected CD8(+) T-cell responses to LMP1 in 9/50(18%) donors and to LMP2 in 15/28 (54%) donors. In addition to the already described epitopes, 3 new LMP1- and 5 new LMP2-derived CD8(+) epitopes were identified. In most donors LMP1- and LMP2-specific CD8(+) precursor frequencies were low compared with precursors against immunodominant EBV epitopes from latent (EBNA3A, -3B and -3C) and lytic cycle antigens. These results demonstrate that CD8(+) memory T cell responses to LMP1 and especially to LMP2 do exist in Caucasians, albeit at low levels and could potentially be exploited for therapeutic use.

Non-myeloablative bone marrow transplantation in an adult with Wiskott-Aldrich syndrome

Early bone marrow transplant is now standard treatment for infants with severe immunodeficiencies such as Wiskott-Aldrich Syndrome (WAS), but results in older children and adults are poor. Non-myeloablative transplant has shown promise in the treatment of older children, who are likely to have active infections and organ damage. We describe a non-myeloablative transplant of a 26-year-old man with WAS, undertaken because of severe infections and vasculitis. Partial engraftment and immunorestoration were achieved. The patient is well 1 year post transplantation.

Complete regression of posttransplant lymphoproliferative disease using partially HLA-matched Epstein Barr virus-specific cytotoxic T cells

BACKGROUND

Adoptive immunotherapy with autologous and donor-derived cytotoxic T lymphocytes (CTL) has recently been used to treat Epstein Barr virus (EBV)-positive posttransplant lymphoproliferative disease (PTLD).

METHODS AND RESULTS

We report complete regression of EBV-positive PTLD in an 18-month-old small bowel and liver transplant recipient after one infusion of partially human leukocyte antigen (HLA)-matched EBV-specific CTL grown ex vivo from an EBV seropositive unrelated blood donor. No infusion-related toxicity or evidence of graft-versus-host disease was observed. The tumor showed signs of regression within 1 week and EBV load in peripheral blood dropped to undetectable levels. Limiting dilution analyses (LDA) detected no EBV-specific CTL precursor (CTLp) cells before the infusion, and high numbers of CTLp at 4 hr and 24 hr post-CTL infusion. There was a reversal of the CD4/8 ratio in peripheral blood and an increase in HLA-DR positive CD8 cells. The patient has been in complete remission for 24 months.

CONCLUSION

If this success is repeated in more PTLD patients, then stored CTL could be used for antiviral and antitumor therapies in immunocompromised patients.

Generation of autologous Epstein-Barr virus-specific cytotoxic T cells for adoptive immunotherapy in solid organ transplant recipients

BACKGROUND

Epstein-Barr virus (EBV)-driven posttransplant lymphoproliferative disorders (PTLD) affect 2%-27% of solid organ transplant (SOT) recipients. Adoptive immunotherapy may have therapeutic potential in this setting, but there is little experience in generating autologous EBV-specific cytotoxic T-cell lymphocytes (EBV-CTLs) from SOT recipients, and their efficacy and persistence in an immunosuppressed environment is unknown.

METHODS

EBV-CTLs were generated from eight SOT recipients, using weekly stimulations with autologous lymphoblastoid cell lines (LCLs) and interleukin-2. CTL phenotype and function were evaluated in the presence of therapeutic concentration of cyclosporin A or FK506.

RESULTS

In all cases, CTLs expanded with normal kinetics. The majority was CD3+CD8+ (mean, 76%), with less than 3% of natural killer cells. All ex vivo-generated CTLs produced significantly higher killing of autologous LCLs than of HLA-mismatched LCLs (mean, 56% vs. 14% at 20:1 ratio). No lysis of autologous or allogeneic PHA blasts was observed. The CTL expansion rate was reduced in a concentration-dependent manner in the presence of immunosuppressive drugs; however, neither lytic activity nor phenotype was affected.

CONCLUSIONS

Using methods that are approved for clinical application, EBV-CTLs can be generated from SOT recipients, even those with frank lymphoma, or who are receiving immunosuppressive drugs. These CTLs retain their function in the presence of immunosuppressive agents. Although in vivo efficacy, safety, and persistence can be assessed only in clinical trials, our results suggest that CTLs can be effective for the treatment of PTLD, even when immunosuppression cannot be reduced because of the high risk of graft rejection.

Induction of the Epstein-Barr virus thymidine kinase gene with concomitant nucleoside antivirals as a therapeutic strategy for Epstein-Barr virus-associated malignancies

Lymphoproliferative diseases (LPDs) associated with the Epstein-Barr virus (EBV) include non-Hodgkin lymphomas, which occur in the setting of immunosuppression, including that induced by human immunodeficiency virus, and posttransplant lymphoproliferative disorders. These LPDs are characterized by actively proliferating, latently infected EBV-positive B lymphocytes and often follow a rapidly progressive fatal clinical course. Pharmacologic treatment for herpesvirus infections has targeted the virus-specific enzyme, thymidine kinase (TK), with nucleoside analogs. The lack of viral TK expression in EBV-positive tumors, caused by viral latency, however, makes antiviral therapy alone ineffective as an antineoplastic therapy. Arginine butyrate selectively activates the EBV TK gene in latently infected EBV-positive tumor cells. We have developed a strategy for treatment of EBV-associated lymphomas using pharmacologic induction of the latent viral TK gene and enzyme in tumor cells using arginine butyrate, followed by treatment with ganciclovir. A phase I/II trial, using an intrapatient dose escalation of arginine butyrate combined with ganciclovir, is underway. This combination therapy has produced complete clinical responses in 5 of 10 previously refractory patients, with partial responses occurring in 2 additional patients. This virus-targeted antitumor strategy may provide a new therapeutic approach to EBV-associated neoplasms.

Diagnosis and management of posttransplant lymphoproliferative disorder in solid-organ transplant recipients

The Epstein-Barr virus (EBV) has a pivotal pathophysiologic role in the development of most lymphoproliferative disorders that occur after solid-organ transplantation. The term "EBV-associated posttransplant lymphoproliferative disorder" (PTLD) includes all clinical syndromes of EBV-associated lymphoproliferation, ranging from uncomplicated posttransplant infectious mononucleosis to true malignancies that contain clonal chromosomal abnormalities. PTLDs are historically associated with a high mortality rate in patients who have a monoclonal form of the disorder. Recently described approaches to pathology, diagnosis, treatment, and preventive strategies of PTLD, however, have the potential to improve outcome.

Functional CD4(+) and CD8(+) T-cell responses induced by autologous mitomycin C treated Epstein-Barr virus transformed lymphoblastoid cell lines

Epstein-Barr virus (EBV) gene expression in tumor cells of posttransplant lymphoproliferative disorder (PTLD) patients resembles that of EBV transformed B-cell lines (LCL). EBV-specific cytotoxic T-lymphocytes can be generated by stimulating peripheral blood lymphocytes with autologous LCL. We describe a standardized method for the growth inactivation and cryopreservation of LCL for optimal T-cell stimulation and analyzed the function and phenotype of responding T-cells. LCL growth was completely blocked by mitomycin C treatment (McLCL) and McLCL could be cryopreserved while retaining excellent APC function. McLCL stimulated both CD4(+) and CD8(+) T-cells as measured by HLA-DR and CD25 expression using FACS analysis. EBV-specific CTL activity and T-cell proliferation were induced and immunocytochemical staining showed CD4(+) and (granzyme B positive) CD8(+) T-cells rosetting with McLCL. Granzymes A and B, IFN-gamma, and IL-6 were detected at significant levels in the supernatant. Thus, ex vivo T-cell activation with cryopreserved McLCL results in activation of both CD4(+) and CD8(+) T-cells producing a Th1-like cytokine profile, making this a suitable protocol for adoptive therapy of PTLD.