Administration of neomycin resistance gene marked EBV specific cytotoxic T-lymphocytes to patients with relapsed EBV-positive Hodgkin disease

Novel agents positively impact chemotherapy and transplantation in Hodgkin lymphoma

INTRODUCTION

Majority of patients with Hodgkin lymphoma (HL) can be successfully cured with frontline conventional therapeutics. Approximately 50-60% of those whose disease recur or is refractory to conventional treatment, can be cured with salvage therapies followed by autologous hematopoietic cell transplantation (AHCT). Conventional treatments, however, may cause significant long-term toxicities. Areas covered: This article reviews the treatment advances in HL with the incorporation of novel and targeted agents that are aimed to improve cure rates while reducing toxicities. Expert opinion: Brentuximab vedotin (BV) and checkpoint inhibitors have demonstrated clear clinical benefit in HL. Majority of patients receive BV before or directly after AHCT as part of salvage or maintenance regimens. In patients who relapse after AHCT, checkpoint inhibitors are the treatment of choice, either as a stand-alone therapy or more commonly as a bridge to a potentially curative allogeneic hematopoietic cell transplantation (alloHCT). A multitude of other targeted agents and combinations, as well as cellular and immunotherapeutic in HL, are under investigation.

Novel agents may positively impact chemotherapy and transplantation in subsets of diffuse large B-cell lymphoma

Introduction: Molecular and biologic heterogeneity in diffuse large B-cell lymphoma (DLBCL) has resulted in a broad range of clinical outcomes. While standard frontline chemoimmunotherapy cures majority of patients with DLBCL, treatment failure in certain DLBCL subsets remains high. Prognosis in these patients is dismal. Therefore, optimization of front-line therapy, as well as development of more effective salvage treatments, is an unmet medical need. Areas covered: This article reviews the treatment advances in DLBCL with novel and targeted agents that are aimed to improve efficacy especially in those with high-risk features. Expert opinion: Incorporation of novel therapies such as immunomodulatory agents and Bruton tyrosine kinase (BTK) inhibitors in the treatment of higher-risk DLBCL subgroups have shown to be effective; however, confirmatory data are required to change the standard of care. While autologous chimeric antigen receptor (CAR) T-cell therapy targeting CD19-positive B-cells have revolutionized the outcomes of refractory DLBCL, the complexity of its production, post-infusion care, and the associated cost, currently has limited its use to select academic centers in the US. A multitude of other targeted agents and combinations as well as cellular and immunotherapeutic agents are under investigation.

Sustained complete responses in patients with lymphoma receiving autologous cytotoxic T lymphocytes targeting Epstein-Barr virus latent membrane proteins

PURPOSE

Tumor cells from approximately 40% of patients with Hodgkin or non-Hodgkin lymphoma express the type II latency Epstein-Barr virus (EBV) antigens latent membrane protein 1 (LMP1) and LMP2, which represent attractive targets for immunotherapy. Because T cells specific for these antigens are present with low frequency and may be rendered anergic by the tumors that express them, we expanded LMP-cytotoxic T lymphocytes (CTLs) from patients with lymphoma using autologous dendritic cells and EBV-transformed B-lymphoblastoid cell lines transduced with an adenoviral vector expressing either LMP2 alone (n = 17) or both LMP2 and ΔLMP1 (n = 33).

PATIENTS AND METHODS

These genetically modified antigen-presenting cells expanded CTLs that were enriched for specificity against type II latency LMP antigens. When infused into 50 patients with EBV-associated lymphoma, the expanded CTLs did not produce infusional toxicities.

RESULTS

Twenty-eight of 29 high-risk or multiple-relapse patients receiving LMP-CTLs as adjuvant therapy remained in remission at a median of 3.1 years after CTL infusion. None subsequently died as a result of lymphoma, but nine succumbed to complications associated with extensive prior chemoradiotherapy, including myocardial infarction and secondary malignancies. Of 21 patients with relapsed or resistant disease at the time of CTL infusion, 13 had clinical responses, including 11 complete responses. T cells specific for LMP as well as nonviral tumor-associated antigens (epitope spreading) could be detected in the peripheral blood within 2 months after CTL infusion, but this evidence for epitope spreading was seen only in patients achieving clinical responses.

CONCLUSION

Autologous T cells directed to the LMP2 or LMP1 and LMP2 antigens can induce durable complete responses without significant toxicity. Their earlier use in the disease course may reduce delayed treatment-related mortality.

Immunotherapy targeting EBV-expressing lymphoproliferative diseases

Epstein-Barr virus (EBV) is associated with non-Hodgkin's lymphoma (NHL), occurring in immunocompetent individuals as well as those with immunodeficiency. In patients with immunodeficiency, the nature of EBV infection in the malignant cell determines the pattern of antigen expression and the associated presence of targets for cellular immunotherapy. EBV-expressing lymphoma cells in the setting of immunodeficiency express type III latency, characterized by expression of all nine latent-cycle EBV antigens, and strategies to restore EBV-specific immune responses have resulted in effective anti-tumour activity. In contrast, EBV-associated NHL in immunocompetent individuals is characterized by type II latency, where a more restricted array of EBV-associated antigens is expressed. In this setting, T-cell therapies are limited by inadequate persistence of transferred T cells and by tumour-evasion strategies. A number of strategies to genetically modify the infused T cells and modulate the host environment are under evaluation.

Engineering human tumor-specific cytotoxic T cells to function in a hypoxic environment

Hypoxia occurs in many tumors and reduces the effectiveness of radio- and chemotherapy. Hypoxia also impedes immune responses to tumors, reducing T lymphocyte production of cytokines such as interleukin-2 (IL-2) and interferon gamma, as well as the survival and proliferation of these cells. We constructed a lentiviral vector encoding a bidirectional hypoxia-inducible responsive element (HRE) derived from human vascular endothelial growth factor, which drives the hIL-2 gene and a marker gene. We used a model of human B cell lymphoma to show that tumor-specific T cells modified with this vector upregulate hIL-2 expression when oxygen tension is low in vitro and in vivo. The consequence of this effect is to increase T-cell survival and proliferation whilst sustaining effector function, even in O(2) concentrations as low as 1%. The phenotype of the transduced cells is unchanged, as is their ability to migrate to tumor. HRE-IL-2-modified cytotoxic T lymphocytes (CTLs) produce faster and more complete tumor regression than parental CTLs and increase overall survival. Hypoxia-resistant T cells may thus be of value in the treatment of human tumors in which areas of hypoxia may otherwise account for resistance to this therapeutic strategy.

Complete responses of relapsed lymphoma following genetic modification of tumor-antigen presenting cells and T-lymphocyte transfer

Epstein-Barr virus (EBV)-associated tumors developing in immunocompetent individuals present a challenge to immunotherapy, since they lack expression of immunodominant viral antigens. However, the tumors consistently express viral proteins including LMP2, which are immunologically "weak" but may nonetheless be targets for immune T cells. We previously showed that a majority of cytotoxic T lymphocytes (CTLs) reactivated using EBV-transformed B-lymphoblastoid cells lines (LCLs) contained minor populations of LMP2-specific T cells and homed to tumor sites. However, they did not produce remissions in patients with bulky disease. We have now used gene transfer into antigen-presenting cells (APCs) to augment the expression and immunogenicity of LMP2. These modified APCs increased the frequency of LMP2-specific CTLs by up to 100-fold compared with unmodified LCL-APCs. The LMP2-specific population expanded and persisted in vivo without adverse effects. Nine of 10 patients treated in remission of high-risk disease remain in remission, and 5 of 6 patients with active relapsed disease had a tumor response, which was complete in 4 and sustained for more than 9 months. It is therefore possible to generate immune responses to weak tumor antigens by ex vivo genetic modification of APCs and the CTLs so produced can have substantial antitumor activity. This study is registered at http://www.cancer.gov/clinicaltrials (protocol IDs: BCM-H-9936, NCT00062868, NCT00070226).

In vivo expansion of LMP 1- and 2-specific T-cells in a patient who received donor-derived EBV-specific T-cells after allogeneic stem cell transplantation

Immunotherapy approaches with antigen-specific cytotoxic T lymphocytes (CTLs) have provided safe and effective prophylaxis and treatment of Epstein-Barr virus (EBV)-associated lymphomas arising after bone marrow transplantation. EBV is also associated with other malignancies including approximately 40% of cases of Hodgkin's disease, making this tumor another potential target for EBV-targeted immunotherapy. This study describes a patient with multiple relapsed EBV positive Hodgkin's Disease who received both autologous and allogeneic EBV CTL lines. After multiple chemotherapeutic and radiotherapy regimens including two autologous stem cell transplants, he received two doses of gene-marked autologous EBV-specific CTL which resulted in disease stabilization for 6 months. The gene-marked EBV-CTL persisted for 12 months in the peripheral blood after which he proceeded to unrelated donor stem cell transplant followed by immunotherapy with donor-derived EBV-specific CTL. Despite low levels of donor chimerism, the patient remains in complete remission 5 years post-allogeneic SCT. Comparison of the autologous and the donor-derived CTL lines showed that the donor line had specificity for two tumor-associated EBV antigens, latent membrane protein (LMP)1 and 2 compared to the autologous line, which only had specificity for LMP2 epitopes. Following infusion of the donor-derived CTL, functional analyses showed that T-cells reactive with both LMP1 and LMP2 epitopes expanded in the peripheral blood, suggesting that strategies to increase their frequency may result in a broader cytotoxic response against EBV+ Hodgkin tumors.

Induction of therapeutic T-cell responses to subdominant tumor-associated viral oncogene after immunization with replication-incompetent polyepitope adenovirus vaccine

The EBV-encoded latent membrane proteins (LMP1 and LMP2), which are expressed in various EBV-associated malignancies have been proposed as a potential target for CTL-based therapy. However, the precursor frequency for LMP-specific CTL is generally low, and immunotherapy based on these antigens is often compromised by the poor immunogenicity and potential threat from their oncogenic potential. Here we have developed a replication- incompetent adenoviral vaccine that encodes multiple HLA class I-restricted CTL epitopes from LMP1 and LMP2 as a polyepitope. Immunization with this polyepitope vaccine consistently generated strong LMP-specific CTL responses in HLA A2/K(b) mice, which can be readily detected by both ex vivo and in vivo T-cell assays. Furthermore, a human CTL response to LMP antigens can be rapidly expanded after stimulation with this recombinant polyepitope vector. These expanded T cells displayed strong lysis of autologous target cells sensitized with LMP1 and/or LMP2 CTL epitopes. More importantly, this adenoviral vaccine was also successfully used to reverse the outgrowth of LMP1-expressing tumors in HLA A2/K(b) mice. These studies demonstrate that a replication-incompetent adenovirus polyepitope vaccine is an excellent tool for the induction of a protective CTL response directed toward multiple LMP CTL epitopes restricted through common HLA class I alleles prevalent in different ethnic groups where EBV-associated malignancies are endemic.

Therapeutic LMP1 polyepitope vaccine for EBV-associated Hodgkin disease and nasopharyngeal carcinoma

Development of an epitope-based vaccination strategy designed to enhance Epstein-Barr virus (EBV)-specific CD8(+) cytotoxic T lymphocytes (CTLs) is increasingly being considered as a preferred approach for the treatment of EBV-associated relapsed Hodgkin disease (HD) and nasopharyngeal carcinoma (NPC). EBV-encoded latent membrane proteins, LMP1 and LMP2, are the only target antigens available for therapeutic augmentation of CTL responses in patients with HD and NPC. Here, we describe preclinical studies using a recombinant poxvirus vaccine that encodes a polyepitope protein comprising 6 HLA A2-restricted epitopes derived from LMP1. Human cells infected with this recombinant polyepitope construct were efficiently recognized by LMP1-specific CTL lines from HLA A2 healthy individuals. Furthermore, immunization of HLA A2/K(b) mice with this polyepitope vaccine consistently generated strong LMP1-specific CTL responses to 5 of the 6 epitopes, which were readily detected by both ex vivo and in vitro assays. More important, this polyepitope vaccine successfully reversed the outgrowth of LMP1-expressing tumors in HLA A2/K(b) mice. These studies provide an important platform for the development of an LMP-based polyepitope vaccine as an immunotherapeutic tool for the treatment of EBV-associated HD and NPC.

Gene Therapy for Pediatric Cancer: State of the Art and Future Perspectives

While modern treatments have led to a dramatic improvement in survival for pediatric malignancy, toxicities are high and a significant proportion of patients remain resistant. Gene transfer offers the prospect of highly specific therapies for childhood cancer. "Corrective" genes may be transferred to overcome the genetic abnormalities present in the precancerous cell. Alternatively, genes can be introduced to render the malignant cell sensitive to therapeutic drugs. The tumor can also be attacked by decreasing its blood supply with genes that inhibit vascular growth. Another possible approach is to modify normal tissues with genes that make them more resistant to conventional drugs and/or radiation, thereby increasing the therapeutic index. Finally, it may be possible to attack the tumor indirectly by using genes that modify the behavior of the immune system, either by making the tumor more immunogenic, or by rendering host effector cells more efficient. Several gene therapy applications have already been reported for pediatric cancer patients in preliminary Phase 1 studies. Although no major clinical success has yet been achieved, improvements in gene delivery technologies and a better understanding of mechanisms of tumor progression and immune escape have opened new perspectives for the cure of pediatric cancer by combining gene therapy with standard therapeutic available treatments.

Role of LMP1 in immune control of EBV infection

The Epstein-Barr virus (EBV) encoded latent membrane protein (LMP1) plays a crucial role in the long-term persistence of this virus within the cells of the immune system. Not only is this protein critical for the transformation of resting B cells by EBV, it also displays pleiotropic effects on various cellular proteins expressed in the host cell. These include up-regulation of expression of B cell activation antigens, adhesion molecules and various components of the antigen processing pathway. Here we discuss how LMP1 acts like an expression 'switch' which, depending on the stage of EBV infection, manoeuvres various pathways that either modulate the immune system towards or against its survival.

Gene transfer and the treatment of haematological malignancy

Gene therapy offers an additional therapeutic modality for treating haematological malignancy. Because gene therapies could be truly specific for the malignancy, they should ultimately prove both safe and effective. We have far to go before this full potential is realized, but gene transfer strategies are already showing therapeutic promise. Gene transfer may be used to correct the genetic defect in the tumour, to render it more susceptible to conventional therapies, or the normal host cells more resistant, to induce or amplify an antitumour immune response, or simply as a means of tracking the tumour or cells used for treatment. This article describes examples of each approach and discusses future prospects for the field.

HIV-specific cytotoxic T lymphocytes traffic to lymph nodes and localize at sites of HIV replication and cell death

We have tracked the in vivo migration and have identified in vivo correlates of cytotoxic T-lymphocyte (CTL) activity in HIV-seropositive subjects infused with autologous gene-marked CD8(+) HIV-specific CTL. The number of circulating gene-marked CTL ranged from 1.6 to 3.5% shortly after infusion to less than 0.5% 2 weeks later. Gene-marked CTL were present in the lymph node at 4.5- to 11-fold excess and colocalized within parafollicular regions of the lymph node adjacent to cells expressing HIV tat fusion transcripts, a correlate of virus replication. The CTL clones expressed the CCR5 receptor and localized among HIV-infected cells expressing the ligands MIP-1alpha and MIP-1beta, CC-chemokines produced at sites of virus replication. Aggregates of apoptotic cells and cells expressing granzyme-B localized within these same sites. In contrast, lymph node sections from untreated HIV-seropositive subjects, all with significant viral burden (> 50,000 HIV RNA copies/mL plasma), showed no CC-chemokine expression and exhibited only sporadic and randomly distributed cells expressing granzymes and/or apoptotic cells. These studies show that the infused CTL specifically migrate to sites of HIV replication and retain their antigen-specific cytolytic potential. Moreover, these studies provide a methodology that will facilitate studies of both the magnitude and functional phenotype of Ag-specific CD8(+) T cells in vivo.

Vaccine strategies against Epstein-Barr virus-associated diseases: lessons from studies on cytotoxic T-cell-mediated immune regulation

Development of a vaccine against Epstein-Barr virus (EBV) is constrained by the latency phenotypes adopted by different EBV-associated diseases. Over the last few years an immense body of information on the pattern of viral gene expression in EBV-associated diseases and the role of cytotoxic T cells in the control of these diseases has accumulated. It would seem reasonable to suggest that emerging technologies are at a level where vaccine trials aimed at controlling infectious mononucleosis, post-transplant lymphoproliferative disease, nasopharyngeal carcinoma and Hodgkin's disease are justified. On the other hand, a more cautious approach may be required for the development of vaccines or immunotherapeutic strategies against Burkitt's lymphoma.

AIDS-associated malignancies: research perspectives

The appearance in 1981 of a usually rare malignancy, Kaposi's sarcoma, in homosexual men [1] was one of the first harbingers of an epidemic caused by a retrovirus, human immunodeficiency virus (HIV), which causes the acquired immunodeficiency syndrome (AIDS). Lymphoid and other malignancies were also increased, most strikingly non-Hodgkin's lymphoma and primary central nervous system (CNS) lymphoma. Advances in molecular biology, immunology, virology, and anti-viral therapy have combined to create unique research opportunities. One developing theme is the role of viral co-infection and malignancy. Human herpes virus 8 (HHV8), Epstein-Barr virus (EBV) and papilloma virus each may have a causal role in the development of HIV-associated malignancy. New antiretroviral therapies are able to substantially reverse or delay the profound immunosuppression of HIV infection. The changes in the epidemiology of malignancies, and understanding the mechanism of action of these new therapeutics provide research opportunities to understand the pathogenesis of these malignancies. The opportunities to discover the consequences of T-cell based immunodeficiency and the interactions with specific viral pathogens will likely lead to progress in HIV treatment and new strategies for other malignancies.