Cellular therapy to control tumor progression:

Characterization of chemokines and adhesion molecules associated with T cell presence in tertiary lymphoid structures in human lung cancer

De novo formation of tertiary lymphoid structures (TLS) has been described in lung cancers. Intratumoral TLS seem to be functional and are associated with a long-term survival for lung cancer patients, suggesting that they represent an activation site for tumor-specific T cells. Here, we characterized T-cell recruitment to TLS in human lung cancer to identify the adhesion molecules and chemoattractants orchestrating this migration. We found that most TLS T cells were CD62L+ and mainly of CD4+ memory phenotype, but naive T cells were highly enriched in these structures as compared with the rest of the tumor. A specific gene expression signature associated with T cell presence was identified in TLS, which included chemokines (CCL19, CCL21, CXCL13, CCL17, CCL22, and IL16), adhesion molecules (ICAM-2, ICAM-3, VCAM-1, and MAdCAM-1) and integrins (alphaL, alpha4, and alphaD). The presence of the corresponding receptors on TLS T cells was confirmed. Intratumoral PNAd+ high endothelial venules also were exclusively associated with TLS and colocalized with CD62L+ lymphocytes. Together, these data bring new insights into the T-cell recruitment to intratumoral TLS and suggest that blood T cell enter into TLS via high endothelial venules, which represent a new gateway for T cells to the tumor. Findings identify the molecules that mediate migration of tumor-specific T cells into TLS where T cell priming occurs, suggesting new strategies to enhance the efficacy of cancer immunotherapies.

Feasibility and safety of adoptive immunotherapy with ex vivo-generated autologous, cytotoxic T lymphocytes in patients with solid tumor

BACKGROUND AIMS

Adoptive T-cell therapy with tumor-specific T cells has emerged as a potentially useful approach for treating patients with advanced malignancies. We have demonstrated previously the feasibility of obtaining large numbers of autologous anti-tumor-specific cytotoxic T lymphocytes (CTL) generated by stimulation of patients' peripheral blood mononuclear cells with dendritic cells pulsed with apoptotic tumor cells. Methods. Six patients with progressing metastatic solid tumors (one renal cell carcinoma, two ovarian cancers, two extraosseous peripheral neuroectodermal tumors, one soft tissue sarcoma) not eligible for conventional therapies were treated with adoptive immunotherapy. Anti-tumor CTL, proven to be reactive in vitro against patient tumor cells, but not against normal cells, were infused following lymphodepleting chemotherapy administered to favor T-cell proliferation in vivo.

RESULTS

Patients received a median of nine CTL infusions (range 2-19). The median number of CTL administered per infusion was 11 × 10(8) (range 1-55 × 10(8)). No patient experienced acute or late adverse events related to CTL infusion, even when large numbers of cells were given. Post-infusion laboratory investigations demonstrated an increase in the frequency of circulating anti-tumor T-cells and, in patients with a longer follow-up receiving two CTL infusions/year, a stabilization of these values.

CONCLUSIONS

Our study demonstrates that autologous ex vivo-generated anti-tumor CTL can be administered safely in patients with advanced solid tumors and can improve the immunologic reactivity of recipients against tumor. These preliminary results provide a rationale for evaluating the clinical efficacy of this immunotherapeutic approach in phase I/II studies.

Improving cancer immunotherapy by targeting tumor-induced immune suppression

The status of a host's immune response influences both the development and progression of a malignancy such that immune responses can have both pro- and anti-tumorigenic effects. Cancer immunotherapy is a form of treatment that aims to improve the ability of a cancer-bearing individual to reject the tumor immunologically. However, antitumor immunity elicited by the host or by immunotherapeutic strategies, can be actively attenuated by mechanisms that limit the strength and/or duration of immune responses, including the presence of immunoregulatory cell types or the production of immunosuppressive factors. As our knowledge of tumor-induced immune suppression increases, it has become obvious that these mechanisms are probably a major barrier to effective therapy. The identification of multiple mechanisms of tumor-induced immune suppression also provides a range of novel targets for new cancer therapies. Given the vital role that a host's immune response is known to play in cancer progression, therapies that target immune suppressive mechanisms have the potential to enhance anticancer immune responses thus leading to better immune surveillance and the limitation of tumor escape. In this review, mechanisms of tumor-associated immune suppression have been divided into four forms that we have designated as (1) regulatory cells; (2) cytokines/chemokines; (3) T cell tolerance/exhaustion and (4) metabolic. We discuss select mechanisms representing each of these forms of immunosuppression that have been shown to aid tumors in evading host immune surveillance and overview therapeutic strategies that have been recently devised to "suppress these suppressors."

Molecular imaging of cell-based cancer immunotherapy

Cell-based cancer immunotherapy represents a new and powerful weapon in the arsenal of anticancer treatments. Non-invasive monitoring of the disposition, migration and destination of therapeutic cells will facilitate the development of cell based therapy. The therapeutic cells can be modified intrinsically by a reporter gene or labeled extrinsically by introducing imaging probes into the cells or on the cell surface before transplant. Various advanced non-invasive molecular imaging techniques are playing important roles in optimizing cellular therapy by tracking cells and monitoring the therapeutic effects of transplanted cells in vivo. This review will summarize the application of multiple molecular imaging modalities in cell-based cancer immunotherapy.

Differential survival of γδT cells, αβT cells and NK cells upon engagement of NKG2D by NKG2DL-expressing leukemic cells

Herein, we show that γδT, CD8(+) αβT lymphocytes and natural killer (NK) cells display a different sensitivity to survival signals delivered via NKG2D surface receptor. All the three effector cell populations activate Akt1/PKBalpha through the engagement of this molecule. Upon binding to leukemic cells expressing NKG2D ligands (NKG2DL), including chronic lymphocytic leukemias treated with transretinoic acid, most γδT (>60%) and half CD8(+) αβT cells (about 50%) received a survival signal, at variance with the majority of NK cells (>80%) that underwent apoptosis by day 5. Interestingly, oligomerization of NKG2D in γδT or CD8(+) αβT cells, led to a significant rise in nuclear/cytoplasmic ratio of both NF-kBp52 and RelB, the two NF-kB subunits mainly involved in the transcription of antiapoptotic proteins of the Bcl family. Indeed, the ratio between the antiapoptotic protein Bcl-2 or Bcl-x(L) and the proapoptotic protein Bax raised in γδT or CD8(+) αβT cells following NKG2D engagement by specific monoclonal antibodies or by NKG2DL expressing leukemic cells. Conversely, nuclear translocation of NF-kBp52 or RelB did not increase, nor the Bcl-2/Bax or the Bcl-x(L) /Bax ratios changed significantly, in NK cells upon oligomerizaton of NKG2D. Of note, transcripts for α5 importin, responsible for nuclear translocation of NF-kBp52/Rel B heterodimer, are significantly higher in γδT and CD8(+) αβT cells than in NK cells. These biochemical data may explain, at least in part, why γδT and CD8(+) αβT cells are cytolytic effector cells more resistant to target-induced apoptosis than NK cells.

Immune reconstitution after allogeneic transplantation and expanding options for immunomodulation: an update

Allogeneic hematopoietic stem cell transplantation (HSCT) has advanced to a common procedure for treating also older patients with malignancies and immunodeficiency disorders by redirecting the immune system. Unfortunately, cure is often hampered by relapse of the underlying disease, graft-versus-host disease, or severe opportunistic infections, which account for the majority of deaths after HSCT. Enhancing immune reconstitution is therefore an area of intensive research. An increasing variety of approaches has been explored preclinically and clinically: the application of cytokines, keratinocyte growth factor, growth hormone, cytotoxic lymphocytes, and mesenchymal stem cells or the blockade of sex hormones. New developments of allogeneic HSCT, for example, umbilical cord blood or haploidentical graft preparations leading to prolonged immunodeficiency, have further increased the need to improve immune reconstitution. Although a slow T-cell reconstitution is regarded as primarily responsible for deleterious infections with viruses and fungi, graft-versus-host disease, and relapse, the importance of innate immune cells for disease and infection control is currently being reevaluated. The groundwork has been prepared for the creation of individualized therapy partially based on genetic features of the underlying disease. We provide an update on selected issues of development in this fast evolving field; however, we do not claim completeness.

Human serum albumin coated iron oxide nanoparticles for efficient cell labeling

A novel dopamine-plus-HSA (human serum albumin) approach was developed to functionalize iron oxide nanoparticles (IONPs), yielding nanoconjugates that are highly efficient in labeling various types of cell lines, which was demonstrated by in vivo MR imaging on xenograft and focal cerebral ischemia models.