Antigen-specific culture of memory-like CD8 T cells for adoptive immunotherapy

Differentiation of Memory CD8 T Cells Unravel Gene Expression Pattern Common to Effector and Memory Precursors

Long-term immunological protection relies on the differentiation and maintenance of memory lymphocytes. Since the knowledge of memory generation has been centered on in vivo models of infection, there are obstacles to deep molecular analysis of differentiating subsets. Here we defined a novel in vitro CD8 T cell activation and culture regimen using low TCR engagement and cytokines to generate differentiated cells consistent with central memory-like cells, as shown by surface phenotype, gene expression profile and lack of cytotoxic function after challenge. Our results showed an effector signature expressed by in vitro memory precursors and their plasticity under specific conditions. Moreover, memory CD8 T cells conferred long-term protection against bacterial infection and slowed in vivo tumor growth more efficiently than effector cells. This model may allow further understanding of CD8 T cell memory molecular differentiation subsets and be suited for generating cells to be used for immunotherapy.

Morphological profiling of human T and NK lymphocytes by high-content cell imaging

The immunological synapse is a complex structure that decodes stimulatory signals into adapted lymphocyte responses. It is a unique window to monitor lymphocyte activity because of development of systematic quantitative approaches. Here we demonstrate the applicability of high-content imaging to human T and natural killer (NK) cells and develop a pipeline for unbiased analysis of high-definition morphological profiles. Our approach reveals how distinct facets of actin cytoskeleton remodeling shape immunological synapse architecture and affect lytic granule positioning. Morphological profiling of CD8⁺ T cells from immunodeficient individuals allows discrimination of the roles of the ARP2/3 subunit ARPC1B and the ARP2/3 activator Wiskott-Aldrich syndrome protein (WASP) in immunological synapse assembly. Single-cell analysis further identifies uncoupling of lytic granules and F-actin radial distribution in ARPC1B-deficient lymphocytes. Our study provides a foundation for development of morphological profiling as a scalable approach to monitor primary lymphocyte responsiveness and to identify complex aspects of lymphocyte micro-architecture.

Oncolytic viruses as engineering platforms for combination immunotherapy

To effectively build on the recent successes of immune checkpoint blockade, adoptive T cell therapy and cancer vaccines, it is critical to rationally design combination strategies that will increase and extend efficacy to a larger proportion of patients. For example, the combination of anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and anti-programmed cell death protein 1 (PD1) immune checkpoint inhibitors essentially doubles the response rate in certain patients with metastatic melanoma. However, given the heterogeneity of cancer, it seems likely that even more complex combinations of immunomodulatory agents may be required to obtain consistent, durable therapeutic responses against a broad spectrum of cancers. This carries serious implications in terms of toxicities for patients, feasibility for care providers and costs for health-care systems. A compelling solution is offered by oncolytic viruses (OVs), which can be engineered to selectively replicate within and destroy tumour tissue while simultaneously augmenting antitumour immunity. In this Opinion article, we argue that the future of immunotherapy will include OVs that function as multiplexed immune-modulating platforms expressing factors such as immune checkpoint inhibitors, tumour antigens, cytokines and T cell engagers. We illustrate this concept by following the trials and tribulations of tumour-reactive T cells from their initial priming through to the execution of cytotoxic effector function in the tumour bed. We highlight the myriad opportunities for OVs to help overcome critical barriers in the T cell journey, leading to new synergistic mechanisms in the battle against cancer.

Smart CARs engineered for cancer immunotherapy

PURPOSE OF REVIEW

Chimeric antigen receptors (CARs) are synthetic immunoreceptors, which can redirect T cells to selectively kill tumor cells, and as 'living drugs' have the potential to generate long-term antitumor immunity. Given their recent clinical successes for the treatment of refractory B-cell malignancies, there is a strong push toward advancing this immunotherapy to other hematological diseases and solid cancers. Here, we summarize the current state of the field, highlighting key variables for the optimal application of CAR T cells for cancer immunotherapy.

RECENT FINDINGS

Advances in CAR T-cell therapy have highlighted intrinsic CAR design and T-cell manufacturing methods as critical components for maximal therapeutic success. Similarly, addressing the unique extrinsic challenges of each tumor type, including overcoming the immunosuppressive tumor microenvironment and tumor heterogeneity, and mitigating potential toxicity, will dominate the next wave of CAR T-cell development.

SUMMARY

CAR T-cell therapeutic optimization, including intrinsic and extrinsic factors, is critical to developing effective CAR T-cell therapies for cancer. The excitement of CAR T-cell immunotherapy has just begun, and will continue with new insights revealed in laboratory research and in ongoing clinical investigations.

Enhanced local and systemic anti-melanoma CD8+ T cell responses after memory T cell-based adoptive immunotherapy in mice

Adoptive cell transfer (ACT) melanoma immunotherapy typically employs acutely activated effector CD8+ T cells for their ability to rapidly recognize and clear antigen. We have previously observed that effector CD8+ T cells are highly susceptible to melanoma-induced suppression, whereas memory CD8+ T cells are not. Although memory T cells have been presumed to be potentially advantageous for ACT, the kinetics of local and systemic T cell responses after effector and memory ACT have not been compared. B16F10 melanoma cells stably transfected to express very low levels of the lymphocytic choriomeningitis virus (LCMV) peptide GP33 (B16GP33) were inoculated into syngeneic C57BL/6 mice. Equal numbers of bona fide naïve, effector, or memory phenotype GP33-specific CD8+ T cells were adoptively transferred into mice 1 day after B16GP33 inoculation. The efficacy of ACT immunotherapy was kinetically assessed using serial tumor measurements and flow cytometric analyses of local and systemic CD8+ T cell responses. Control of B16GP33 tumor growth, persistence of adoptively transferred CD8+ cells, intratumoral infiltration of CD8+ T cells, and systemic CD8+ T cell responsiveness to GP33 were strongest after ACT of memory CD8+ T cells. Following surgical tumor resection and melanoma tumor challenge, only mice receiving memory T cell-based ACT immunotherapy exhibited durable tumor-specific immunity. These findings demonstrate how the use of non-expanded memory CD8+ T cells may enhance ACT immunotherapeutic efficacy.