Katherine M. Audsley

The efficacy of chimeric antigen receptor (CAR) T cell therapy in solid tumours is limited by immunosuppression and antigen heterogeneity1–3. To overcome these barriers, ‘armoured’ CAR T cells, which secrete proinflammatory cytokines, have been developed4. However, their clinical application has been limited because of toxicity related to peripheral expression of the armouring transgene5. Here, we have developed a CRISPR knock-in strategy that leverages the regulatory mechanisms of endogenous genes to drive transgene expression in a tumour-localized manner. By screening endogenous genes with tumour-restricted expression, we have identified the NR4A2 and RGS16 promoters as promising candidates to support the delivery of cytokines such as IL-12 and IL-2 directly to the tumour site, leading to enhanced antitumour efficacy and long-term survival of mice in both syngeneic and xenogeneic models. This effect was concomitant with improved CAR T cell polyfunctionality, activation of endogenous antitumour immunity and a favourable safety profile, and was applicable in CAR T cells from patients. A CRISPR knock-in strategy that uses endogenous gene regulatory mechanisms can engineer ‘armoured’ CAR T cells that secrete proinflammatory cytokines directly within a tumour without causing toxicity, leading to prolonged survival in mice.

The use of dendritic cells (DCs) to generate effective anti-tumor T cell immunity has garnered much attention over the last thirty-plus years. Despite this, limited clinical benefit has been demonstrated thus far. There has been a revival of interest in DC-based treatment strategies following the remarkable patient responses observed with novel checkpoint blockade therapies, due to the potential for synergistic treatment. Cross-presenting DCs are recognized for their ability to prime CD8+ T cell responses to directly induce tumor death. Consequently, they are an attractive target for next-generation DC-based strategies. In this review, we define the universal classification system for cross-presenting DCs, and the vital role of this subset in mediating anti-tumor immunity. Furthermore, we will detail methods of targeting these DCs both ex vivo and in vivo to boost their function and drive effective anti-tumor responses.

Natural killer (NK) cells play a significant and vital role in the first line of defense against infection through their ability to target cells without prior sensitization. They also contribute significantly to the activation and recruitment of both innate and adaptive immune cells through the production of a range of cytokines and chemokines. In the context of cytomegalovirus (CMV) infection, NK cells and CMV have co-evolved side by side to employ several mechanisms to evade one another. However, during this co-evolution the discovery of a subset of long-lived NK cells with enhanced effector potential, increased antibody-dependent responses and the potential to mediate immune memory has revolutionized the field of NK cell biology. The ability of a virus to imprint on the NK cell receptor repertoire resulting in the expansion of diverse, highly functional NK cells to this day remains a significant immunological phenomenon that only occurs in the context of CMV. Here we review our current understanding of the development of these NK cells, commonly referred to as adaptive NK cells and their current role in transplantation, infection, vaccination and cancer immunotherapy to decipher the complex role of CMV in dictating NK cell functional fate.

Cancer vaccination drives the generation of anti-tumor T cell immunity and can be enhanced by the inclusion of effective immune adjuvants such as type I interferons (IFNs). Whilst type I IFNs have been shown to promote cross-priming of T cells, the role of individual subtypes remains unclear. Here we systematically compared the capacity of distinct type I IFN subtypes to enhance T cell responses to a whole-cell vaccination strategy in a pre-clinical murine model. We show that vaccination in combination with IFNβ induces significantly greater expansion of tumor-specific CD8 + T cells than the other type I IFN subtypes tested. Optimal expansion was dependent on the presence of XCR1 + dendritic cells, CD4 + T cells, and CD40/CD40L signaling. Therapeutically, vaccination with IFNβ delayed tumor progression when compared to vaccination without IFN. When vaccinated in combination with anti-PD-L1 checkpoint blockade therapy (CPB), the inclusion of IFNβ associated with more mice experiencing complete regression and a trend in increased overall survival. This work demonstrates the potent adjuvant activity of IFNβ, highlighting its potential to enhance cancer vaccination strategies alone and in combination with CPB.

Immunotherapies harnessing T cell immunity have shown remarkable clinical success for the management of cancer. However, only a proportion of patients benefit. The presence of type I interferon (IFN) within the tumour microenvironment is critical for driving effective tumour-specific T cell immunity. Individuals can produce 12 distinct subtypes of IFNα, which all signal through a common receptor. Despite reported differences in anti-viral potencies, the concept that distinct IFNα subtypes can improve anti-cancer treatments remains unclear. We tested whether expression of unique IFNα subtypes confined to the tumour microenvironment enhances tumour control. This was systematically evaluated by transplantation of B16 murine melanoma cells secreting five unique IFNα subtypes (B16_IFNα2; B16_IFNα4; B16_IFNα5; B16_IFNα6; B16_IFNα9) into a pre-clinical murine model. We show that IFNα2 and IFNα9 are the only subtypes capable of completely controlling tumour outgrowth, with this protection dependent on the presence of an adaptive immune response. We next determined whether these differences extended to other model systems and found that the adoptive transfer of tumour-specific CD8+ T cells engineered to secrete IFN9 delays tumour growth significantly and improves survival, whereas no enhanced survival was observed using T cells secreting IFN4. Overall, our data shows that the expression of distinct IFNα subtypes within the tumour microenvironment results in different anti-tumour activities, and differentially affects the efficacy of a cancer therapy targeting established disease.