Claudia Rossig

Virus-specific T cells engineered to coexpress tumor-specific receptors: persistence and antitumor activity in individuals with neuroblastoma

Cytotoxic T lymphocytes (CTLs) directed to nonviral tumor–associated antigens do not survive long term and have limited antitumor activity in vivo, in part because such tumor cells typically lack the appropriate costimulatory molecules. We therefore engineered Epstein-Barr virus (EBV)-specific CTLs to express a chimeric antigen receptor directed to the diasialoganglioside GD2, a nonviral tumor–associated antigen expressed by human neuroblastoma cells. We reasoned that these genetically engineered lymphocytes would receive optimal costimulation after engagement of their native receptors, enhancing survival and antitumor activity mediated through their chimeric receptors. Here we show in individuals with neuroblastoma that EBV-specific CTLs expressing a chimeric GD2-specific receptor indeed survive longer than T cells activated by the CD3-specific antibody OKT3 and expressing the same chimeric receptor but lacking virus specificity. Infusion of these genetically modified cells seemed safe and was associated with tumor regression or necrosis in half of the subjects tested. Hence, virus-specific CTLs can be modified to function as tumor-directed effector cells.

Antitumor activity and long-term fate of chimeric antigen receptor–positive T cells in patients with neuroblastoma

We generated MHC-independent chimeric antigen receptors (CARs) directed to the GD2 antigen expressed by neuroblastoma tumor cells and treated patients with this disease. Two distinguishable forms of this CAR were expressed in EBV-specific cytotoxic T lymphocytes (EBV-CTLs) and activated T cells (ATCs). We have previously shown that EBV-CTLs expressing GD2-CARs (CAR-CTLs) circulated at higher levels than GD2-CAR ATCs (CAR-ATCs) early after infusion, but by 6 weeks, both subsets became low or undetectable. We now report the long-term clinical and immunologic consequences of infusions in 19 patients with high-risk neuroblastoma: 8 in remission at infusion and 11 with active disease. Three of 11 patients with active disease achieved complete remission, and persistence of either CAR-ATCs or CAR-CTLs beyond 6 weeks was associated with superior clinical outcome. We observed persistence for up to 192 weeks for CAR-ATCs and 96 weeks for CAR-CTLs, and duration of persistence was highly concordant with the percentage of CD4(+) cells and central memory cells (CD45RO(+)CD62L(+)) in the infused product. In conclusion, GD2-CAR T cells can induce complete tumor responses in patients with active neuroblastoma; these CAR T cells may have extended, low-level persistence in patients, and such persistence was associated with longer survival. This study is registered at www.clinialtrials.gov as #NCT00085930.

Targeting of GD2‐positive tumor cells by human T lymphocytes engineered to express chimeric T‐cell receptor genes

Genetic engineering of human T lymphocytes to express tumor antigen‐specific chimeric immune receptors is an attractive means for providing large numbers of effector cells for adoptive immunotherapy while bypassing major mechanisms of tumor escape from immune recognition. We have applied this strategy to the targeting of a GD2‐positive tumor, neuroblastoma, which is the commonest extracranial solid tumor of childhood. Chimeric immune receptors were generated by joining an extracellular antigen‐binding domain derived from either of the 2 ganglioside GD2‐specific antibodies sc7A4 and sc14.G2a to a cytoplasmic signaling domain. The variable domains of hybridoma antibody 14.G2a were cloned and selected using a phage display approach. Upon coincubation with GD2‐expressing tumor cell targets, human T lymphocytes transduced with recombinant retroviruses encoding chimeric receptors based on sc14.G2a, but not sc7A4, secreted significant levels of cytokines in a pattern comparable to the cytokine response obtained by engagement of the CD3 receptor. T cells transduced with the sc14.G2a‐based chimeric T‐cell receptors also displayed specific lysis of GD2‐positive neuroblastoma cells, which was blocked in the presence of monoclonal antibody 14.G2a. In the absence of nonspecific stimulation of transduced cells, their functionality declined over time and antigenic stimulation of the chimeric receptor alone did not induce commitment to proliferation. These results support the feasibility of redirecting human T lymphocytes to a tumor‐associated ganglioside epitope but emphasize that successful chimeric receptor‐mediated adoptive immunotherapy will require additional strategies that overcome functional inactivation of gene‐modified primary T lymphocytes.

2B4 (CD244) signaling by recombinant antigen-specific chimeric receptors costimulates natural killer cell activation to leukemia and neuroblastoma cells.

Purpose: Novel natural killer (NK) cell–directed strategies in cancer immunotherapy aim at specifically modulating the balance between NK cell receptor signals toward tumor-specific activation. The signaling lymphocyte activation molecule–related receptor 2B4 (CD244) is an important regulator of NK cell activation. We investigated whether 2B4-enhanced activation signals can redirect the cytolytic function of human NK cells to NK cell–resistant and autologous leukemia and tumor targets. Experimental Design: In vitro–stimulated NK cells from healthy donors and pediatric leukemia patients were gene modified with CD19 or GD2-specific chimeric receptors containing either the T-cell receptor ζ or 2B4 endodomain alone or combined. Results: Chimeric 2B4 signaling alone failed to induce interleukin-2 receptor up-regulation and cytokine secretion but triggered a specific degranulation response. Integration of the 2B4 endodomain into T-cell receptor ζ chimeric receptors significantly enhanced all aspects of the NK cell activation response to antigen-expressing leukemia or neuroblastoma cells, including CD25 up-regulation, secretion of IFN-γ and tumor necrosis factor-α, release of cytolytic granules, and growth inhibition, and overcame NK cell resistance of autologous leukemia cells while maintaining antigen specificity. Conclusion: These data indicate that the 2B4 receptor has a potent costimulatory effect in NK cells. Antigen-specific 2B4ζ-expressing NK cells may be a powerful new tool for adoptive immunotherapy of leukemia and other malignancies.

Relapsed or Refractory Anaplastic Large-Cell Lymphoma in Children and Adolescents After Berlin-Frankfurt-Muenster (BFM)–Type First-Line Therapy: A BFM-Group Study

PURPOSE To evaluate risk factors for outcome in children and adolescents with relapse of anaplastic large-cell lymphoma (ALCL) after comparable first-line therapy. PATIENTS AND METHODS We analyzed a population-based cohort of 74 children with relapsed ALCL after Berlin-Frankfurt-Muenster-type first-line therapy between April 1990 and December 2003. The recommended salvage strategy was reinduction chemotherapy followed by autologous hematopoietic stem-cell transplantation (SCT). RESULTS With a median follow-up time of 8.4 years (range, 4.5 to 16.4 years), the 5-year overall survival (OS) rate after first relapse was 57% ± 6%. Survival correlated with time of relapse and clinically advanced dissemination. Five-year OS of 16 patients who experienced progression during first-line therapy was 25% ± 11% compared with 66% ± 6% for 58 patients with a later relapse (P = .002). Five-year OS of 11 patients with bone marrow or CNS involvement was 27% ± 13% compared with 62% ± 6% for 63 patients without involvement (P = .001). Five-year event-free survival (EFS) and OS of 39 children who received the recommended autologous SCT were 59% ± 8% and 77% ± 7%, respectively. EFS after autologous SCT was significantly associated with time to relapse (progression: n = 3; EFS, 0; later relapse: n = 36; EFS, 64% ± 8%; P = .014) and CD3 expression (CD3 negative: n = 25; EFS, 72% ± 9%; CD3 positive: n = 11; EFS, 18% ± 12%; P < .001), but not with site of relapse, conditioning regimen, or graft manipulation. No relapses occurred among 10 patients with relapsed CD3-positive ALCL treated with allogeneic SCT. CONCLUSION Reinduction chemotherapy followed by autologous SCT proved feasible and efficacious for patients with a first relapse of CD3-negative ALCL after first-line therapy. Patients with progression during first-line therapy or relapsed CD3-positive ALCL may benefit from allogeneic SCT.

Adoptive T-cell therapy with hexon-specific Th1 cells as a treatment of refractory adenovirus infection after HSCT

Hematopoietic stem cell transplantation (HSCT) has improved over the last few decades. However, viral infections are often refractory to pharmacologic treatment and require alternative treatment strategies such as immunotherapy. Adenovirus (AdV) is th predominant disease-causing pathogen in pediatric HSCT. In a clinical trial, we analyzed safety and efficacy of ex vivo adoptive T-cell transfer (ACT) with hexon-specific T cells, predominantly of the T-helper cell 1 (Th1) phenotype, in 30 patients with AdV disease or viremia. ACT was feasible with no acute toxicities or significant onset of graft-versus-host disease. ACT led to in vivo antiviral immunity for up to 6 months with viral control, resulting in complete clearance of viremia in 86% of patients with antigen-specific T-cell responses. After ACT and a follow-up of 6 months, overall survival was markedly increased in responders (mean, 122 days; 15 survivors) compared with nonresponders who all died shortly after ACT (mean, 24 days; no survivors). AdV-related mortality was 100% in nonresponders compared with 9.5% in responders (≥1 log reduction of DNA copies per milliliter after ACT). In summary, ex vivo ACT of AdV-specific Th1 cells was well tolerated and led to successful and sustained restoration of T-cell immunity correlated with virologic response and protection from virus-related mortality. This cellular immunotherapy is a short-term available and broadly applicable treatment. The study is registered at European Union Clinical Trials Register as 2005-001092-35.

Human γδ T cells as mediators of chimaeric‐receptor redirected anti‐tumour immunity

Human peripheral blood γδ T cells (Vγ9+ Vδ2+) can be selectively expanded in vivo by the systemic administration of aminobisphosphonates without prior antigen priming. To assess the potential of human γδ T cells to serve as effector cells of specific anti‐tumour immunity, we expanded peripheral blood‐derived γδ T cells and transduced them with recombinant retrovirus encoding GD2‐ or CD19‐specific chimaeric receptors. Flow cytometric analysis of T cells from four individual donors cultured in the presence of zoledronate at day 14 of culture showed selective enrichment of the γδ T cell population (Vγ9+ Vδ2+ CD3+ CD4− CD8−) to 73–96% of total CD3+ T cells. Retroviral gene transfer resulted in chimaeric receptor surface expression in 73 ± 12% of the population. Transduced γδ T cells efficiently recognized antigen‐expressing tumour cell targets, as demonstrated by target‐specific upregulation of CD69 and secretion of interferon‐α. Moreover, transduced γδ T cells efficiently and specifically lysed the antigen‐expressing tumour targets. They could be efficiently expanded in vitro and maintained in culture for prolonged periods. Zoledronate‐activated human γδ T cells expressing chimaeric receptors may thus serve as potent and specific anti‐tumour effector cells. Their responsiveness to stimulation with aminobisphosphonates may enable the selective re‐expansion of adoptively transferred T cells in vivo, permitting long lasting anti‐tumour immune control.

Dexamethasone vs prednisone in induction treatment of pediatric ALL: results of the randomized trial AIEOP-BFM ALL 2000

Induction therapy for childhood acute lymphoblastic leukemia (ALL) traditionally includes prednisone; yet, dexamethasone may have higher antileukemic potency, leading to fewer relapses and improved survival. After a 7-day prednisone prephase, 3720 patients enrolled on trial Associazione Italiana di Ematologia e Oncologia Pediatrica and Berlin-Frankfurt-Münster (AIEOP-BFM) ALL 2000 were randomly selected to receive either dexamethasone (10 mg/m(2) per day) or prednisone (60 mg/m(2) per day) for 3 weeks plus tapering in induction. The 5-year cumulative incidence of relapse (± standard error) was 10.8 ± 0.7% in the dexamethasone and 15.6 ± 0.8% in the prednisone group (P < .0001), showing the largest effect on extramedullary relapses. The benefit of dexamethasone was partially counterbalanced by a significantly higher induction-related death rate (2.5% vs 0.9%, P = .00013), resulting in 5-year event-free survival rates of 83.9 ± 0.9% for dexamethasone and 80.8 ± 0.9% for prednisone (P = .024). No difference was seen in 5-year overall survival (OS) in the total cohort (dexamethasone, 90.3 ± 0.7%; prednisone, 90.5 ± 0.7%). Retrospective analyses of predefined subgroups revealed a significant survival benefit from dexamethasone only for patients with T-cell ALL and good response to the prednisone prephase (prednisone good-response [PGR]) (dexamethasone, 91.4 ± 2.4%; prednisone, 82.6 ± 3.2%; P = .036). In patients with precursor B-cell ALL and PGR, survival after relapse was found to be significantly worse if patients were previously assigned to the dexamethasone arm. We conclude that, for patients with PGR in the large subgroup of precursor B-cell ALL, dexamethasone especially reduced the incidence of better salvageable relapses, resulting in inferior survival after relapse. This explains the lack of benefit from dexamethasone in overall survival that we observed in the total cohort except in the subset of T-cell ALL patients with PGR. This trial was registered at www.clinicaltrials.gov (BFM: NCT00430118, AIEOP: NCT00613457).

A high proportion of bone marrow T cells with regulatory phenotype (CD4+CD25hiFoxP3+) in Ewing sarcoma patients is associated with metastatic disease

Immunosuppressive CD4+CD25hiFoxP3+ T cells (Treg cells) have been found at increased densities within the tumor microenvironment in many malignancies and interfere with protective antitumor immune responses. Osseous Ewing sarcomas (ESs) are thought to derive from a bone marrow (BM) mesenchymal cell of origin, and microscopic marrow involvement defines a subpopulation of patients at a high risk of relapse. We hypothesized that BM‐resident T cells may contribute to a permissive milieu for immune escape of ESs. Using 6‐color‐flow cytometry, we investigated the pattern of immune cell subset distribution including NK cells, γδ T cells, central and effector memory CD8+ and CD4+ T cells as well as T cells with regulatory phenotype (Treg cells) in BM obtained at diagnosis from 45 primary or relapsed ES patients treated within standardized protocols. Although patients at relapse had an inverted CD4:CD8 T‐cell ratio, neither CD8+ effector/memory T‐cell subsets nor Treg cells significantly differed from patients at diagnosis. No significant associations of innate and effector/memory T‐cell subpopulations with known risk factors were found, including age, gender, tumor site, primary metastases and histological tumor response. By contrast, Treg cells were found at significantly higher frequencies in patients with primary metastatic disease compared with localized ESs (5.0 vs. 3.3%, p = 0.01). Thus, increased BM Treg cells in patients with metastasized ES may reflect an immune escape mechanism that contributes to the development of metastatic disease. Immunotherapeutic strategies will have to adequately consider the regulatory milieu within areas of Ewing tumor‐immune interactions.

Effective childhood cancer treatment: The impact of large scale clinical trials in Germany and Austria

In Germany and Austria, more than 90% of pediatric cancer patients are enrolled into nationwide disease‐specific first‐line clinical trials or interim registries. Essential components are a pediatric cancer registry and centralized reference laboratories, imaging review, and tumor board assistance. The five‐year overall survival rate in countries where such infrastructures are established has improved from <20% before 1950 to >80% since 1995. Today, treatment intensity is tailored to the individual patients risk to provide the highest chances of survival while minimizing deleterious late effects. Multicenter clinical trials are internationalized and serve as platforms for further improvements by novel drugs and biologicals. Pediatr Blood Cancer 2013;60:1574–1581.