Successful treatment with reduced-intensity stem cell transplantation in a case of relapsed refractory central nervous system lymphoma

Natural Killer Cells: Development, Maturation, and Clinical Utilization

Natural killer (NK) cells are the predominant innate lymphocyte subsets that mediate anti-tumor and anti-viral responses, and therefore possess promising clinical utilization. NK cells do not express polymorphic clonotypic receptors and utilize inhibitory receptors (killer immunoglobulin-like receptor and Ly49) to develop, mature, and recognize “self” from “non-self.” The essential roles of common gamma cytokines such as interleukin (IL)-2, IL-7, and IL-15 in the commitment and development of NK cells are well established. However, the critical functions of pro-inflammatory cytokines IL-12, IL-18, IL-27, and IL-35 in the transcriptional-priming of NK cells are only starting to emerge. Recent studies have highlighted multiple shared characteristics between NK cells the adaptive immune lymphocytes. NK cells utilize unique signaling pathways that offer exclusive ways to genetically manipulate to improve their effector functions. Here, we summarize the recent advances made in the understanding of how NK cells develop, mature, and their potential translational use in the clinic.

Engineering Hematopoietic Cells for Cancer Immunotherapy: Strategies to Address Safety and Toxicity Concerns

Advances in cancer immunotherapies utilizing engineered hematopoietic cells have recently generated significant clinical successes. Of great promise are immunotherapies based on chimeric antigen receptor-engineered T (CAR-T) cells that are targeted toward malignant cells expressing defined tumor-associated antigens. CAR-T cells harness the effector function of the adaptive arm of the immune system and redirect it against cancer cells, overcoming the major challenges of immunotherapy, such as breaking tolerance to self-antigens and beating cancer immune system-evasion mechanisms. In early clinical trials, CAR-T cell-based therapies achieved complete and durable responses in a significant proportion of patients. Despite clinical successes and given the side effect profiles of immunotherapies based on engineered cells, potential concerns with the safety and toxicity of various therapeutic modalities remain. We discuss the concerns associated with the safety and stability of the gene delivery vehicles for cell engineering and with toxicities due to off-target and on-target, off-tumor effector functions of the engineered cells. We then overview the various strategies aimed at improving the safety of and resolving toxicities associated with cell-based immunotherapies. Integrating failsafe switches based on different suicide gene therapy systems into engineered cells engenders promising strategies toward ensuring the safety of cancer immunotherapies in the clinic.

Developing T-cell therapies for lymphoma without receptor engineering

T-cell therapy has emerged from the bench for the treatment of patients with lymphoma. Responses to T-cell therapeutics are regulated by multiple factors, including the patient's immune system status and disease stage. Outside of engineering of chimeric antigen receptors and artificial T-cell receptors, T-cell therapy can be mediated by ex vivo expansion of antigen-specific T cells targeting viral and/or nonviral tumor-associated antigens. These approaches are contributing to enhanced clinical responses and overall survival. In this review, we summarize the available T-cell therapeutics beyond receptor engineering for the treatment of patients with lymphoma.

Developing T-cell therapies for lymphoma without receptor engineering

T-cell therapy has emerged from the bench for the treatment of patients with lymphoma. Responses to T-cell therapeutics are regulated by multiple factors, including the patient's immune system status and disease stage. Outside of engineering of chimeric antigen receptors and artificial T-cell receptors, T-cell therapy can be mediated by ex vivo expansion of antigen-specific T cells targeting viral and/or nonviral tumor-associated antigens. These approaches are contributing to enhanced clinical responses and overall survival. In this review, we summarize the available T-cell therapeutics beyond receptor engineering for the treatment of patients with lymphoma.

Graft versus tumor effect in the brain of a child with recurrent metastatic medulloblastoma

Marrow ablative chemotherapy (MAC) with autologous hematopoietic stem cell transplantation (HSCT) is limited by poor bone marrow reserve after chemotherapy and/or radiotherapy, and the extent of bone/bone marrow disease. We report a child with recurrent metastatic medulloblastoma who received an allogeneic HSCT while in relapse and subsequently achieved radiological resolution of disease and favorable marrow minimal residual disease (MRD) response. Disease recurred intra-cranially at 304 days post-HSCT. Tumor biopsy 488 days post-HSCT showed infiltration with donor lymphocytes demonstrating graft-versus-tumor (GVT) effect. The patient remained alive >2 years post-HSCT. Allogeneic HSCT may be a consideration for high-risk recurrent medulloblastoma.

Rescue by hematopoietic progenitor cells derived from engrafted cord blood unit in a child with brain tumor after transplantation for T-cell acute lymphoblastic leukemia

An 8-year-old boy with T-cell acute lymphoblastic leukemia received unrelated cord blood transplantation in April 2006. His course was uneventful until February 2007, when a hyperintense lesion was noted in the pons. A subsequent bone marrow examination confirmed that he was in remission with full donor chimerism. He was therefore diagnosed with an inoperable brain tumor after cord blood transplantation. Despite radiotherapy for the brain lesion, his neurological status worsened. High-dose chemotherapy with "autologous" progenitor cell rescue was adopted, although the fact that these cells were originally derived from engrafted umbilical cord unit. He was in apparent remission of his brain tumor for 3 years.

Regression of the tumor after withdrawal of cyclosporine in relapsed extranodal natural killer/T cell lymphoma following allogeneic hematopoietic stem cell transplantation

The prognosis of patients with advanced-stage extranodal natural killer/T cell lymphoma, nasal type (ENKL) has been generally poor, and several anecdotal reports have suggested the role of allogeneic hematopoietic stem cell transplantation (HSCT). A potential advantage of allogeneic HSCT may be the graft-versus-lymphoma (GVL) effect. The susceptibility to the GVL effect, however, has been shown to vary according to histologic subtypes, and it has been hardly documented yet whether ENKL is susceptible to the GVL effect. Here we report a patient with advanced-stage ENKL who underwent allogeneic HSCT from an HLA one-allele mismatched related donor, whose clinical course after HSCT suggested the potent GVL effect against ENKL. A 43-year-old female underwent allogeneic HSCT for advanced-stage, chemorefractory ENKL, and achieved complete response. In 4 months after the transplantation, however, the ENKL relapsed in multiple sites. These lesions markedly responded to the discontinuation of immunosuppressive agents and disappeared. Except for a temporal exacerbation of bronchiolitis obliterans organizing pneumonia, she has been free from disease for more than a year without other treatments against lymphoma. The clinical course of the current patient suggests the potent GVL effect against ENKL. Allogeneic HSCT, including that with reduced-intensity regimens, is a promising treatment option for high-risk ENKL.

Intrathecal donor lymphocyte infusion for the treatment of suspected refractory lymphomatous meningitis: a case report

A 43-year-old female with large T-cell non-Hodgkin's lymphoma and central nervous system (CNS) involvement underwent HLA-identical-sibling peripheral blood stem cell transplantation (SCT) during her third complete remission. She presented a possible refractory CNS relapse 5 months after the transplant. She was then treated with intrathecal (IT) donor lymphocyte infusions (DLI). No side effects were observed after three DLI injections. The patient died 13 months later from infectious complications with no evidence of progressive disease. To our knowledge, this is the first case report of IT DLI for possible refractory lymphomatous meningitis.

The graft-versus-lymphoma effect: clinical review and future opportunities

Numerous lines of preclinical and clinical evidence support the existence of a graft-versus-leukemia effect, but less evidence supporting a comparable graft-versus-lymphoma effect exists. We review here current clinical data addressing the graft-versus-lymphoma effect, including comparisons of autologous, syngeneic, and allogeneic transplantation; responses to immunomodulation; and responses to nonmyeloablative stem cell transplantation. Despite several limitations of the data, we believe that there is sufficient evidence suggesting a significant graft-versus-lymphoma effect. In addition, we discuss approaches for clinical management of lymphoma patients, opportunities for mechanistic studies afforded by donor leukocyte infusions and nonmyeloablative transplantation, and suggestions for clinical studies to further define the magnitude and applicability of the graft-versus-lymphoma effect.

Diagnosis and Treatment of Central Nervous System Involvement in Non-Hodgkin's Lymphoma

The diagnosis of lymphoma of the central nervous system (CNS) has been facilitated by advances in neuroimaging and laboratory analysis of cerebrospinal fluid. The most common form of central nervous system CNS involvement in non-Hodgkin's lymphoma (NHL) is leptomeningeal disease. After a diagnosis is established, the use of intrathecal or systemic chemotherapy and radiotherapy can improve survival and palliate symptoms. High-dose systemic chemotherapy with hematopoietic stem cell transplantation is an important treatment option at central nervous system relapse of NHL and for primary CNS lymphoma. The prognosis for disease-free survival and cure is better for patients who have treatment of CNS disease before transplantation than for patients who have active central nervous system disease at the time of transplant.

Leukemic relapse in the central nervous system after allogeneic stem cell transplantation with complete remission in the bone marrow and donor-type chimerism: report of two cases

We studied two cases with leukemia that relapsed in the central nervous system (CNS) after allogeneic stem cell transplantation. One patient underwent peripheral blood stem cell transplantation (SCT) from a related, yet haplotype-mismatched, donor for chronic myelomonocytic leukemia. She was kept in complete remission (CR) in the bone marrow (BM) for 7 months, until relapse in the cerebrospinal fluid (CSF) was evident. In the other patient, with acute lymphoblastic leukemia, systemic relapse occurred when he was still on immunosuppression 6 months after SCT from an unrelated donor. After induction chemotherapy following cessation of immunosuppression, the BM examination proved CR. During consolidation chemotherapy, however, he developed leukemic dissemination in the CSF, despite the fact that the BM was in CR. Chimerism status in the BM mononuclear cells and fractionated peripheral blood (PB) cells (granulocytes, T-lymphocytes, and the others) was assessed by short tandem repeat analysis. In both patients, the BM cells and all the fractions of the PB cells proved donor-type chimeras. These results seem to suggest that the graft-versus-leukemia effects might not be as effective in the CNS as in the BM, even when complete T-lymphoid chimerism is achieved.