Intrinsic modulation of lymphocyte function by stromal cell network: advance in therapeutic targeting of cancer

Immune checkpoint blockade for hematologic malignancies: a review

Immune checkpoint blockade has revolutionized the treatment of cancer, with impressive responses seen in a broad variety of tumor types. Blockade of immune checkpoints and immune signaling antibodies has shown promise in multiple types of hematologic malignancies (HMs), with dramatic single agent responses for pembrolizumab and nivolumab in Hodgkin lymphoma (HL). In this review, we outline the current state of immune checkpoint blockade drug development in HMs, and discuss mechanisms of activity and resistance, and highlight potential targets in the immune tumor microenvironment (TME). Blockade of T-cell checkpoint molecules PD-1/PD-L1 and CTLA-4 are the most clinically mature of the immune checkpoint strategies. Novel and upcoming strategies for immune checkpoint blockade drug development in HMs using innovative combinations to modulate immunologic targets shows significant promise as a way to expand the number of patients with blood cancers who could benefit from immunotherapy.

Adoptive immunotherapy for cancer

Recent clinical success has underscored the potential for immunotherapy based on the adoptive cell transfer (ACT) of engineered T lymphocytes to mediate dramatic, potent, and durable clinical responses. This success has led to the broader evaluation of engineered T-lymphocyte-based adoptive cell therapy to treat a broad range of malignancies. In this review, we summarize concepts, successes, and challenges for the broader development of this promising field, focusing principally on lessons gleaned from immunological principles and clinical thought. We present ACT in the context of integrating T-cell and tumor biology and the broader systemic immune response.

Tumor-promoting immune-suppressive myeloid-derived suppressor cells in the multiple myeloma microenvironment in humans

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous, immature myeloid cell population with the ability to suppress immune responses. MDSCs have been characterized in infections, inflammatory diseases, and solid tumors; however, their presence and role in the tumor-promoting, immune-suppressive microenvironment in hematologic malignancies remains unclear. We assessed the presence, frequency, and functional characteristics of MDSCs in patients with newly diagnosed, relapsed, and relapsed/refractory multiple myeloma (MM) compared with healthy donors. Additionally, we evaluated the immunomodulatory effects of lenalidomide and bortezomib on MDSCs in MM. CD11b(+)CD14(-)HLA-DR(-/low)CD33(+)CD15(+) MDSCs were significantly increased in both the peripheral blood and the bone marrow of patients with active MM compared with healthy donors. Furthermore, MDSCs induced MM growth while suppressing T-cell-mediated immune responses. Conversely, MM cells induced the development of MDSCs from healthy donor peripheral blood mononuclear cells, confirming a bidirectional interaction between MDSCs and MM cells and immune effector cells. Our results further suggest that MDSCs may be associated with the activity of disease in MM. Importantly, our studies suggest that inhibition of the tumor-promoting and immune-suppressive functions of MDSCs in MM may represent a promising novel immune-based therapeutic strategy.

Immune activation and antitumor response of ar-turmerone on P388D1 lymphoblast cell implanted tumors

Aromatic turmerone (ar-turmerone) has been reported to have a cytotoxic effect on L-1210 and HL-60 cells. In the present study, we investigated the anticancer responses and immune activities in implanted tumor cells. Our study found that ar-turmerone inhibited the increase in the number of white blood cells, which normally increase by the injection of lymphoblast cells, or P388D1, and ar-turmerone increased lymphocyte percentage compared to the control. Tumor inhibition rate in the ar-turmerone-treated group was 11.79%, and the apoptosis indexes of the control, ar-turmerone and Glivec groups were 4.22±1.02, 5.45±1.46 and 10.01±2.01, respectively, in which only the Glivec-treated group showed a significance. The positive rates of Bcl-2 and Bax proteins which were treated by ar-turmerone did not show marked differences compared to the control group, but the Bax protein in the Glivec-treated group increased compared to the control group. The density of caspase-1, -3, -6, -9, Bcl-2, Bax, p21 and p53 mRNA in the control, ar-turmerone and Glivec groups did not change considerably, but the Bax mRNA of the Glivec-treated group increased compared to the control group. The ar-turmerone-treated group increased T-lymphocyte and B-lymphocyte proliferation activities compared to the control group, which was more significant in T-lymphocyte than in B-lymphocyte proliferation activity. The interleukin-2 (IL2) production activity of the ar-turmerone group increased compared to the control group. These findings suggest that ar-turmerone does not have a chemotherapeutic effect on tumor incidence, but it has a repressive effect on P388D1 lymphocytic leukemia. Furthermore, this protective effect of ar-turmerone from P388D1 lymphocytic leukemia resulted from the increased activity of tumor immunogenicity through increased T-lymphokine production and increased percentage of lymphocytes.

Toward integrative cancer immunotherapy: targeting the tumor microenvironment

The development of cancer has historically been attributed to genomic alterations of normal host cells. Accordingly, the aim of most traditional cancer therapies has been to destroy the transformed cells themselves. There is now widespread appreciation that the progressive growth and metastatic spread of cancer cells requires the cooperation of normal host cells (endothelial cells, fibroblasts, other mesenchymal cells, and immune cells), both local to, and at sites distant from, the site at which malignant transformation occurs. It is the balance of these cellular interactions that both determines the natural history of the cancer, and influences its response to therapy. This active tumor-host dynamic has stimulated interest in the tumor microenvironment as a key target for both cancer diagnosis and therapy. Recent data has demonstrated both that the presence of CD8⁺ T cells within a tumor is associated with a good prognosis, and that the eradication of all malignantly transformed cells within a tumor requires that the intra-tumoral concentration of cytolytically active CD8⁺ effector T cells remain above a critical concentration until every tumor cell has been killed. These findings have stimulated two initiatives in the field of cancer immunotherapy that focus on the tumor microenvironment. The first is the development of the immune score as part of the routine diagnostic and prognostic evaluation of human cancers, and the second is the development of combinatorial immune-based therapies that reduce tumor-associated immune suppression to unleash pre-existing or therapeutically-induced tumor immunity. In support of these efforts, the Society for the Immunotherapy of Cancer (SITC) is sponsoring a workshop entitled "Focus on the Target: The Tumor Microenvironment" to be held October 24-25, 2012 in Bethesda, Maryland. This meeting should support development of the immune score, and result in a position paper highlighting opportunities for the development of integrative cancer immunotherapies that sculpt the tumor microenvironment to promote definitive tumor rejection.