Administration of latent membrane protein 2-specific cytotoxic T lymphocytes to patients with relapsed Epstein-Barr virus-positive lymphoma

Constitutive Interleukin-7 Cytokine Signaling Enhances the Persistence of Epstein-Barr Virus-Specific T-Cells

The efficacy of therapeutic T-cells is limited by a lack of positive signals and excess inhibitory signaling in tumor microenvironments. We previously showed that a constitutively active IL7 receptor (C7R) enhanced the persistence, expansion, and anti-tumor activity of T-cells expressing chimeric antigen receptors (CARs), and C7R-modified GD2.CAR T-cells are currently undergoing clinical trials. To determine if the C7R could also enhance the activity of T-cells recognizing tumors via their native T-cell receptors (TCRs), we evaluated its effects in Epstein-Barr virus (EBV)-specific T-cells (EBVSTs) that have produced clinical benefits in patients with EBV-associated malignancies. EBVSTs were generated by stimulation of peripheral blood T-cells with overlapping peptide libraries spanning the EBV lymphoma antigens, LMP1, LMP2, and EBNA 1, followed by retroviral vector transduction to express the C7R. The C7R increased STAT5 signaling in EBVSTs and enhanced their expansion over 30 days of culture in the presence or absence of exogenous cytokines. C7R-EBVSTs maintained EBV antigen specificity but were dependent on TCR stimulation for continued expansion. C7R-EBVSTs produced more rapid lymphoma control in a murine xenograft model than unmodified EBVSTs and persisted for longer. The findings have led to a clinical trial, evaluating C7R-EBVSTs for the treatment of refractory or relapsed EBV-positive lymphoma (NCT04664179).

Potency assays and biomarkers for cell-based advanced therapy medicinal products

Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded in vitro, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy in vivo. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy in vivo of these cell-based drugs.

Identification of protective T-cell antigens for smallpox vaccines

Background aims

E3L is an immediate-early protein of vaccinia virus (VV) that is detected within 0.5 h of infection, potentially before the many immune evasion genes of vaccinia can exert their protective effects. E3L is highly conserved among orthopoxviruses and hence could provide important protective T-cell epitopes that should be retained in any subunit or attenuated vaccine. We have therefore evaluated the immunogenicity of E3L in healthy VV-vaccinated donors.

Methods

Peripheral blood mononuclear cells from healthy volunteers (n = 13) who had previously received a smallpox vaccine (Dryvax) were activated and expanded using overlapping E3L peptides and their function, specificity and antiviral activity was analyzed. E3L-specific T cells were expanded from 7 of 12 (58.3%) vaccinated healthy donors. Twenty-five percent of these produced CD8+ T-cell responses and 87.5% produced CD4+ T cells. We identified epitopes restricted by HLA-B35 and HLA-DR15.

Results

E3L-specific T cells killed peptide-loaded target cells as well as vaccinia-infected cells, but only CD8+ T cells could prevent the spread of infectious virus in virus inhibition assays. The epitopes recognized by E3L-specific T cells were shared with monkeypox, and although there was a single amino acid change in the variola epitope homolog, it was recognized by vaccinia-specific T-cells.

Conclusions

It might be important to include E3L in any deletion mutant or subunit vaccine and E3L could provide a useful antigen to monitor protective immunity in humans.

Highlights of the second international conference on "Immunotherapy in Pediatric Oncology"

The Second International Conference on Immunotherapy in Pediatric Oncology was held in Houston, Texas, USA, October 11-12, 2010, to discuss the progress and challenges that have occurred in cutting edge immunotherapeutic strategies currently being developed for pediatric oncology. Major topics included immune targeting of acute lymphoblastic leukemia and pediatric solid tumors, chimeric antigen receptors (CARs) for hematologic malignancies and solid tumors, enhancing graft-versus-leukemia for pediatric cancers, overcoming hurdles of immunotherapy, strategies to active the innate immune system, and moving immunotherapy beyond phase I studies. Significant progress has been made in the last 2 years both in the development of novel immunobiologics such as CARs, and in establishing survival benefits of an anti-GD2 monoclonal antibody in randomized studies. Although there is much excitement going forward, a great deal of laboratory and regulatory challenges lie ahead in improving the efficacy of each of these modalities as well as getting them to patients in a timely and cost-effective fashion. The resulting discussions will hopefully lead to new collaborations and insight for further translational and clinical studies.

Combining mTor inhibitors with rapamycin-resistant T cells: a two-pronged approach to tumor elimination

Despite activity as single agent cancer therapies, Rapamycin (rapa) and its rapalogs may have their greatest effects when combined with other therapeutic modalities. In addition to direct antitumor activity, rapalogs reverse multiple tumor-intrinsic immune evasion mechanisms. These should facilitate tumor-specific T cell activity, but since rapa directly inhibits effector T cells, this potential immune enhancement is lost. We hypothesized that if T cells were rendered resistant to rapa they could capitalize on its downregulation of tumor immune evasion. We therefore modified T cells with a rapa-resistant mutant of mTor, mTorRR, and directed them to B lymphomas by coexpressing a chimeric antigen receptor (CAR) for CD19 (CAR.CD19-28ζ). T cells expressing transgenic mTorRR from a piggyBac transposon maintain mTor signaling, proliferate in the presence of rapa and retain their cytotoxic function and ability to secrete interferon-γ (IFNγ) after stimulation, effector functions that were inhibited by rapa in control T cells. In combination, rapa and rapa-resistant-CAR.CD19-28ζ-expressing T cells produced greater antitumor activity against Burkitt's lymphoma and pre-B ALL cell lines in vitro than CAR.CD19-28ζ T cells or rapa alone. In conclusion, the combination of rapa and rapa-resistant, CAR.CD19-28ζ-expressing T cells may provide a novel therapy for the treatment of B cell malignancies and other cancers.

Biomarkers in T cell therapy clinical trials

T cell therapy represents an emerging and promising modality for the treatment of both infectious disease and cancer. Data from recent clinical trials have highlighted the potential for this therapeutic modality to effect potent anti-tumor activity. Biomarkers, operationally defined as biological parameters measured from patients that provide information about treatment impact, play a central role in the development of novel therapeutic agents. In the absence of information about primary clinical endpoints, biomarkers can provide critical insights that allow investigators to guide the clinical development of the candidate product. In the context of cell therapy trials, the definition of biomarkers can be extended to include a description of parameters of the cell product that are important for product bioactivity.

This review will focus on biomarker studies as they relate to T cell therapy trials, and more specifically: i. An overview and description of categories and classes of biomarkers that are specifically relevant to T cell therapy trials, and ii. Insights into future directions and challenges for the appropriate development of biomarkers to evaluate both product bioactivity and treatment efficacy of T cell therapy trials.

Novel treatment strategies for patients with relapsed classical Hodgkin lymphoma

Although classical Hodgkin lymphoma (HL) is considered one of the most curable human cancers, the treatment of patients with relapsed and refractory disease, especially those who relapse after autologous stem cell transplantation, remains challenging. Furthermore, because the median age of the patients is in the mid-30s, the impact of early mortality on the number of years lost from productive life is remarkable. Patients with HL whose disease relapses after stem cell transplantation are rarely cured with current treatment modalities. New drugs and novel treatment strategies that are based on our understanding of the disease biology and signaling pathways are needed to improve treatment outcome for these patients. This review will focus on emerging new treatment modalities that are currently under investigation for patients with relapsed classical HL.

Adoptive cell therapy against EBV-related malignancies: a survey of clinical results

BACKGROUND

Epstein-Barr Virus (EBV) infection is associated with a heterogeneous group of tumors, including lymphoproliferative disorders, Hodgkin's disease, nasopharyngeal carcinoma and Burkitt's lymphoma. As such neoplastic disorders express viral antigens, they can be treated by adoptive immunotherapy strategies relying mostly on in vitro generation and expansion of virus-specific cytotoxic T lymphocytes (CTL), which can be administered to patients for both prophylaxis and treatment.

OBJECTIVE

We reviewed results obtained in all clinical trials reported thus far employing anti-EBV adoptive immunotherapy for different virus-related malignancies.

METHODS

'PTLD after HSCT', 'PTLD after SOT', 'NPC', 'HD', 'SCAEBV' and 'extranodal NK/T cell lymphoma', in combination with 'Adoptive immunotherapy' and 'Adoptive transfer', were used as search keys for papers in PubMed.

CONCLUSIONS

Although the heterogeneity of different studies precludes their collection for a meta-analysis, it can be inferred that adoptive therapy with EBV-specific CTL is safe, well tolerated and particularly effective in the case of most immunogenic tumors, like post-transplant lymphoproliferative disease.

T-cell therapy after hematopoietic stem cell transplantation

PURPOSE OF REVIEW

The separation of graft versus host disease from graft versus leukaemia reactivity and the reconstitution of immunity to infectious agents are the main goals of T-cell therapy after allogeneic hematopoietic stem cell transplantation. We describe how an improved understanding of T-cell mediated graft versus leukemia and of antiviral responses is providing effective approaches to T-cell immunotherapy.

RECENT FINDINGS

Over the past several years, researchers have developed strategies to eliminate alloreactive T cells from the graft, to expand naturally occurring regulatory T cells, and to select and expand antigen-specific T cells specific for tumor-associated or viral antigens. Incorporation of suicide genes allows the selective destruction of allodepleted or antigen-selected cells after infusion, further increasing the safety and potential applicability of these approaches.

SUMMARY

In this review we describe current strategies for adoptive T-cell immunotherapy after hematopoietic stem cell transplantation.

T cell therapies following hematopoietic stem cell transplantation: surely there must be a better way than DLI?

Advances in the past few years have significantly improved adoptive immunotherapy strategies available following autologous and allogeneic hematopoietic stem cell transplantation (HSCT). Minimal residual disease, relapsed disease and viral infections remain a significant cause of mortality in patients undergoing HSCT. Novel therapies are critically needed to overcome these management dilemmas, while sparing the graft-versus-tumor effect and avoiding graft-versus-host disease. This review focuses on the T-cell strategies currently available to allay disease while minimizing toxicities in patients who have undergone HSCT.

Epstein-Barr Virus and Hodgkin Lymphoma

Epstein-Barr virus (EBV) is detected in some Hodgkin lymphoma (HL) tumor cells. Primary infection is associated with infectious mononucleosis and EBV+ HL. Vaccines and antiviral drugs show promise in modulating the clinical course of infectious mononucleosis. Their impact on HL is entirely unknown. T-cell function may be important in the pathogenesis of HL. In HIV patients, higher CD4 counts are associated with an increased incidence of EBV+ HL. One of the roles of the virus in the pathogenesis of HL may be to mimic signals associated with surface immunoglobulin molecules. New approaches to imaging EBV-associated tumors may be on the horizon. Adoptive immunotherapy and virus-specific pharmacologic therapies offer promise for future treatment.