CD19-Targeted chimeric antigen receptor-modified T-cell immunotherapy for B-cell malignancies.

Chimeric antigen receptors (CARs) comprise a tumor-targeting moiety, often in the form of a single chain variable fragment derived from a monoclonal antibody, fused to one or more intracellular T-cell signaling sequences. Lymphodepletion chemotherapy followed by infusion of T cells that are genetically modified to express a CD19-specific CAR is a promising therapy for patients with refractory CD19(+) B-cell malignancies, producing rates of complete remission that are remarkably high in acute lymphoblastic leukemia and encouraging in non-Hodgkin lymphoma and chronic lymphocytic leukemia. Responses are often durable, although additional studies are needed to define the role of CAR-T cell immunotherapy in the context of other treatments. CAR-modified T-cell immunotherapy can be complicated by cytokine release syndrome and neurologic toxicity, which in most cases are manageable and reversible. Here we review recent clinical trial data and discuss issues for the field.

Chimeric antigen receptor-modified T cells derived from defined CD8+ and CD4+ subsets confer superior antitumor reactivity in vivo.

Adoptive T-cell therapy with gene-modified T cells expressing a tumor-reactive T-cell receptor or chimeric antigen receptor (CAR) is a rapidly growing field of translational medicine and has shown success in the treatment of B-cell malignancies and solid tumors. In all reported trials, patients have received T-cell products comprising random compositions of CD4(+) and CD8(+) naive and memory T cells, meaning that each patient received a different therapeutic agent. This variation may have influenced the efficacy of T-cell therapy, and complicates comparison of outcomes between different patients and across trials. We analyzed CD19 CAR-expressing effector T cells derived from different subsets (CD4(+)/CD8(+) naive, central memory, effector memory). T cells derived from each of the subsets were efficiently transduced and expanded, but showed clear differences in effector function and proliferation in vitro and in vivo. Combining the most potent CD4(+) and CD8(+) CAR-expressing subsets, resulted in synergistic antitumor effects in vivo. We show that CAR-T-cell products generated from defined T-cell subsets can provide uniform potency compared with products derived from unselected T cells that vary in phenotypic composition. These findings have important implications for the formulation of T-cell products for adoptive therapies.

Practical blood dendritic cell vaccination for immunotherapy of multiple myeloma.

Therapeutic vaccination combined with new drugs may cure multiple myeloma (MM). We have developed a bio-process to purify CMRF-56 monoclonal antibody (mAb) and a standard operating procedure to immunoselect blood dendritic cells (BDC). Leucopheresed mononuclear cells were cultured overnight, labelled with CMRF-56 mAb and BDC prepared using a clinical scale immunoselection system. The mean BDC yield from healthy donors was 48% (n = 6, purity 28%). Preparations from MM patients (n = 6, yield 47%, purity 35%) primed cytotoxic T lymphocytes (CTL) to clinically relevant MM antigens. This procedure can be performed readily by clinical cell manufacturing units to facilitate BDC vaccination studies.

DC in multiple myeloma immunotherapy.

Therapy for patients with multiple myeloma (MM) is currently unsatisfactory and most patients eventually succumb to relapsed disease. DCs are a subset of leukocytes with the capacity to initiate and control the adaptive immune response against many cancers, including MM. In MM patients, in vivo DC function is often abnormal, however, it appears that it can be restored by in vitro manipulation. This has led to the development of DC immunotherapy for MM patients. We review the background research leading to the recognition of an anti-MM immune response, and discuss abnormalities in DC function, potential tumor-associated Ags, and the results of clinical trials of DC immunotherapy in MM patients.

The immune response to breast cancer, and the case for DC immunotherapy.

The long-held belief that breast cancer is a weakly immunogenic tumor and a poor candidate for immunotherapy should be reappraised. There is ample evidence for the existence of an immune response, which is, however, attenuated by multiple inhibitory factors. Many tumor-associated antigens (TAA) have been identified in breast cancer, some of which appear to play a critical role in tumorigenesis and may be attractive targets for immunotherapy. There is evidence for DC recruitment and activation within breast cancers, and the presence of intratumoral activated DCs impacts favorably upon survival. Furthermore, there is a striking paucity of activated DCs within the primary draining or sentinel lymph nodes of breast cancers. Tumor infiltrating lymphocytes (TIL) are often documented, however, their function is impaired by inhibitory cytokines, increased regulatory T lymphocyte activity, tumor cell MHC molecule alterations, and aberrant Fas ligand expression, amongst others. DCs are recognized as one of the critical interfaces between a cancer and the immune system, and have emerged as a promising platform for cancer vaccination via ex vivo immunomodulation. Clinical evaluation of DC vaccination in breast cancer is still relatively limited, although evolving. This article details evidence for the immune response in breast cancer and its many failings, and reviews the clinical trials and significant preclinical data which, taken together, validate the concept of DC vaccination in breast cancer.

Dendritic cells in tumor immunology and immunotherapy.

Despite rapid advances in cancer therapeutics, relapsed disease due to failed immunosurveillance remains a major problem in many cancers. Dendritic cells are recognized as key to the induction of immune responses to cancer and intensive study is underway to facilitate their use in cancer immunotherapy. In initial clinical trials, dendritic cell preparations were, with the benefit of hindsight, largely sub-optimal, yet encouraging results have been seen. The challenge now is to expand our knowledge of the interactions between tumors and the immune system, through basic scientific research and coordinated large-scale clinical studies. This review focuses on the anti-tumor immune response, human dendritic cell biology and the results of recent clinical studies of dendritic cell immunotherapy for cancer.