Will T-cell therapy for cancer ever be a standard of care?

CD4-/CD8- double-negative tumor-infiltrating lymphocytes expanded from solid tumor tissue suppress the proliferation of tumor cells in an MHC-independent way

PURPOSE

Tumor-infiltrating lymphocytes (TILs) have shown remarkable clinical responses in some patients with advanced solid tumors. As a rare subset of TILs, CD4^-/CD8^- double-negative T cells (DNTs) were poorly known. This study aims to investigate the characteristics and function of CD3⁺CD4^-CD8^- TILs (double-negative TIL, DN-TILs) derived from solid tumor.

METHODS

DN-TILs were derived and expanded ex vivo from resected gastric carcinoma tissue and phenotyped by flow cytometry. The cytotoxicity of DN-TILs was determined against established tumor cell lines in vitro or through in vivo adoptive transfer into xenograft models. K562 cells were transferred with the HLA gene to verify whether the cytotoxicity of DN-TILs was MHC-independent.

RESULTS

Flow cytometric analysis revealed a high-purity population of DN-TILs (> 97%) within CD3⁺ TILs, which expanded more than 800-folds in 2 weeks, consisting of a mixture of alpha-beta (αβ) and gamma-delta (γδ) T-cell receptor (TCR)-expressing cells (with the majority being αβ-TCR, > 95%). Using single-cell RNA sequencing, the expanded DN-TILs were categorized into four main subsets, Natural Killer T cells (approximately 80%, 5563 in 7028), Progenitor cells, Germ cells and T helper2 cells. DN-TILs exhibited a broad anticancer cytotoxicity in a donor-unrestricted manner against various cancer cell lines derived from pancreatic cancer (Panc-1), gastric cancer (HGC-27), ovarian cancer (SKOV-3), malignant melanoma (A375). The cytotoxicity was MHC-independent, which was not altered in K562 transferring with HLA gene or not. DN-TILs significantly reduced tumor volume in xenograft models with superior tumor-homing ability and low off-target toxicity.

CONCLUSION

Gastric carcinoma derived DN-TIL can target tumor cells in vitro and in vivo. DN-TILs have the potential to be used as a adoptive cell therapy for solid cancers with both the advantages of DNT and TIL.

Methods and Process Optimization for Large-Scale CAR T Expansion Using the G-Rex Cell Culture Platform

The G-Rex cell culture platform is based on a gas-permeable membrane technology that provides numerous advantages over other systems. Conventional bioreactor platform technologies developed for large scale mammalian cell expansion are typically constrained by the mechanics of delivering oxygen to an expanding cell population. These systems often utilize complex mechanisms to enhance oxygen delivery, such as stirring, rocking, or perfusion, which adds to expense and increases their overall risk of failure. On the other hand, G-Rex gas-permeable membrane-based bioreactors provide a more physiologic environment and avoid the risk and cost associated with more complex systems. The result is a more robust, interacting cell population established through unlimited oxygen and nutrients that are available on demand. By removing the need to actively deliver oxygen, these bioreactors can hold larger medium volumes (more nutrients) which allows the cells to reach a maximum density without complexity or need for media exchange. This platform approach is scaled to meet the needs of research through commercial production with a direct, linear correlation between small and large devices. In the G-Rex platform, examples of cell expansion (9-14 day duration) include; CAR-T cells, which have atypical harvest density of 20-30 × 10⁶/cm² (or 2-3 × 10⁹ cells in a 100 cm² device); NK cells, which have a typical harvest density of 20-30 × 10⁶/cm² (or 2-3 × 10⁹ cells in a 100 cm² device) and numerous other cell types that proliferate without the need for intervention or complex processes normally associated with large scale culture. Here we describe the methods and concepts used to optimize expansion of various cell types in the static G-Rex bioreactor platform.

Antigen-independent killer cells prepared for adoptive immunotherapy: One source, divergent protocols, diverse nomenclature

Adoptive cell therapy (ACT) using tumor antigen-independent killer cells has been widely used in clinical trials of cancer treatment. Circumventing the need for identification of a particular tumor-associated antigen on tumor cells, the approach has opened possibilities for the extension of ACT immunotherapy to patients with a wide variety of cancer types. Namely, Natural Killer (NK), Lymphokine-activated Killer (LAK) cells and Cytokine-induced killer (CIK) cells are the most commonly used cell types in antigen-independent adoptive immunotherapy of cancer. They all originate from peripheral blood mononuclear cells and share several common features in their killing mechanisms. However, despite broad application in clinical settings, the boundaries between these cell types are not very clearly defined. The current study aims to review different aspects of these cell populations in terms of phenotypical characteristic and preparation media, to clarify how the boundaries are set.

Are clinical trials with mesenchymal stem/progenitor cells too far ahead of the science? Lessons from experimental hematology

The cells referred to as mesenchymal stem/progenitor cells (MSCs) are currently being used to treat thousands of patients with diseases of essentially all the organs and tissues of the body. Strikingly positive results have been reported in some patients, but there have been few prospective controlled studies. Also, the reasons for the beneficial effects are frequently unclear. As a result there has been a heated debate as to whether the clinical trials with these new cell therapies are too far ahead of the science. The debate is not easily resolved, but important insights are provided by the 60-year history that was required to develop the first successful stem cell therapy, the transplantation of hematopoietic stem cells. The history indicates that development of a dramatically new therapy usually requires patience and a constant dialogue between basic scientists and physicians carrying out carefully designed clinical trials. It also suggests that the field can be moved forward by establishing better records of how MSCs are prepared, by establishing a large supply of reference MSCs that can be used to validate assays and compare MSCs prepared in different laboratories, and by continuing efforts to establish in vivo assays for the efficacy of MSCs. Stem Cells2014;32:3055–3061

Past, present and future targets for immunotherapy in ovarian cancer

Ovarian cancer is the leading cause of death from gynecologic malignancy in the US. Treatments have improved with conventional cytotoxic chemotherapy and advanced surgical techniques but disease recurrence is common and fatal in nearly all cases. Current evidence suggests that the immune system and its ability to recognize and eliminate microscopic disease is paramount in preventing recurrence. Ovarian cancer immunotherapy is targeting tumors through active, passive and adoptive approaches. The goal of immunotherapy is to balance the activation of the immune system against cancer while preventing the potential for tremendous toxicity elicited by immune modulation. In this paper we will review the different immunotherapies available for ovarian cancer as well as current ongoing studies and potential future directions.

Towards a commercial process for the manufacture of genetically modified T cells for therapy

The recent successes of adoptive T-cell immunotherapy for the treatment of hematologic malignancies have highlighted the need for manufacturing processes that are robust and scalable for product commercialization. Here we review some of the more outstanding issues surrounding commercial scale manufacturing of personalized-adoptive T-cell medicinal products. These include closed system operations, improving process robustness and simplifying work flows, reducing labor intensity by implementing process automation, scalability and cost, as well as appropriate testing and tracking of products, all while maintaining strict adherence to Current Good Manufacturing Practices and regulatory guidelines. A decentralized manufacturing model is proposed, where in the future patients' cells could be processed at the point-of-care in the hospital.

Gene therapy on the move

The first gene therapy clinical trials were initiated more than two decades ago. In the early days, gene therapy shared the fate of many experimental medicine approaches and was impeded by the occurrence of severe side effects in a few treated patients. The understanding of the molecular and cellular mechanisms leading to treatment- and/or vector-associated setbacks has resulted in the development of highly sophisticated gene transfer tools with improved safety and therapeutic efficacy. Employing these advanced tools, a series of Phase I/II trials were started in the past few years with excellent clinical results and no side effects reported so far. Moreover, highly efficient gene targeting strategies and site-directed gene editing technologies have been developed and applied clinically. With more than 1900 clinical trials to date, gene therapy has moved from a vision to clinical reality. This review focuses on the application of gene therapy for the correction of inherited diseases, the limitations and drawbacks encountered in some of the early clinical trials and the revival of gene therapy as a powerful treatment option for the correction of monogenic disorders.

Immunotherapeutic strategies to target prognostic and predictive markers of cancer

Throughout the last century medical advances in cancer treatment in the fields of surgery, radiation therapy and chemotherapy have greatly impacted patients' survival rates. Nevertheless, cancer remains a significant cause of mortality, with an estimated 7.6 million deaths worldwide in 2008, reflecting the inability of existing therapies to effectively cure disease. The emergence of vaccines and their successes in preventing the spread of infectious diseases has demonstrated the unique specificity and therapeutic potential of the immune system. This potential has driven the development of novel cancer immunotherapeutics. This review focuses on the current status of the use of immunologic effectors to target known biomarkers in cancer.

Randomized selection design trial evaluating CD8+-enriched versus unselected tumor-infiltrating lymphocytes for adoptive cell therapy for patients with melanoma

PURPOSE

Adoptive cell therapy (ACT) with autologous tumor-infiltrating lymphocytes (TILs) and high-dose interleukin-2 (IL-2) administered to lymphodepleted patients with melanoma can cause durable tumor regressions. The optimal TIL product for ACT is unknown.

PATIENTS AND METHODS

Patients with metastatic melanoma were prospectively assigned to receive unselected young TILs versus CD8(+)-enriched TILs. All patients received lymphodepleting chemotherapy and high-dose IL-2 therapy and were assessed for response, toxicity, survival, and immunologic end points.

RESULTS

Thirty-four patients received unselected young TILs with a median of 8.0% CD4(+) lymphocytes, and 35 patients received CD8(+)-enriched TILs with a median of 0.3% CD4(+) lymphocytes. One month after TIL infusion, patients who received CD8(+)-enriched TILs had significantly fewer CD4(+) peripheral blood lymphocytes (P = .01). Twelve patients responded to therapy with unselected young TILs (according to Response Evaluation Criteria in Solid Tumors [RECIST]), and seven patients responded to CD8(+)-enriched TILs (35% v 20%; not significant). Retrospective studies showed a significant association between response to treatment and interferon gamma secretion by the infused TILs in response to autologous tumor (P = .04), and in the subgroup of patients who received TILs from subcutaneous tumors, eight of 15 patients receiving unselected young TILs responded but none of eight patients receiving CD8(+)-enriched TILs responded.

CONCLUSION

A randomized selection design trial was feasible for improving individualized TIL therapy. Since the evidence indicates that CD8(+)-enriched TILs are not more potent therapeutically and they are more laborious to prepare, future studies should focus on unselected young TILs.

Collapse of the tumor stroma is triggered by IL-12 induction of Fas

Engineering CD8⁺ T cells to deliver interleukin 12 (IL-12) to the tumor site can lead to striking improvements in the ability of adoptively transferred T cells to induce the regression of established murine cancers. We have recently shown that IL-12 triggers an acute inflammatory environment that reverses dysfunctional antigen presentation by myeloid-derived cells within tumors and leads to an increase in the infiltration of adoptively transferred antigen-specific CD8⁺ T cells. Here, we find that local delivery of IL-12 increased the expression of Fas within tumor-infiltrating macrophages, dendritic cells, and myeloid-derived suppressor cells (MDSC), and that these changes were abrogated in mice deficient in IL-12-receptor signaling. Importantly, upregulation of Fas in host mice played a critical role in the proliferation and antitumor activity of adoptively transferred IL-12-modified CD8⁺ T cells. We also observed higher percentages of myeloid-derived cell populations within tumors in Fas-deficient mice, indicating that tumor stromal destruction was dependent on the Fas death receptor. Taken together, these results describe the likely requirement for costimulatory reverse signaling through Fasl on T cells that successfully infiltrate tumors, a mechanism triggered by the induction of Fas expression on myeloid-derived cells by IL-12 and the subsequent collapse of the tumor stroma.

An efficient low cost method for gene transfer to T lymphocytes

Gene transfer to T lymphocytes has historically relied on retro and lentivirus, but recently transposon-based gene transfer is rising as a simpler and straight forward approach to achieve stable transgene expression. Transfer of expression cassettes to T lymphocytes remains challenging, being based mainly on commercial kits.

AIMS

We herein report a convenient and affordable method based on in house made buffers, generic cuvettes and utilization of the widely available Lonza nucleofector II device to promote efficient gene transfer to T lymphocytes.

RESULTS

This approach renders high transgene expression levels in primary human T lymphocytes (mean 45%, 41-59%), the hard to transfect murine T cells (mean 38%, 36-42% for C57/BL6 strain) and human Jurkat T cell line. Cell viability levels after electroporation allowed further manipulations such as in vitro expansion and Chimeric Antigen Receptor (CAR) mediated gain of function for target cell lysis.

CONCLUSIONS

We describe here an efficient general protocol for electroporation based modification of T lymphocytes. By opening access to this protocol, we expect that efficient gene transfer to T lymphocytes, for transient or stable expression, may be achieved by an increased number of laboratories at lower and affordable costs.