Skin immunization for effective treatment of multifocal melanoma refractory to PD1 blockade and Braf inhibitors.

BACKGROUND: Despite the remarkable benefits associated with the interventional treatment of melanomas (and other solid cancers) with immune checkpoint and Braf inhibitors (Brafi), most patients ultimately progress on therapy. The presence of multifocal/disseminated disease in patients increases their mortality risk. Hence, the development of novel strategies to effectively treat patients with melanomas that are resistant to anti-PD1 mAb (αPD1) and/or Brafi, particularly those with multifocal/disseminated disease remains a major unmet clinical need. METHODS: Mice developing induced/spontaneous BrafV600E/Pten-/- melanomas were treated by cutaneous immunization with a DNA vaccine encoding the melanoma-associated antigen TRP2, with Brafi or αPD1 alone, or with a combination of these treatments. Tumor progression, tumor-infiltration by CD4+ and CD8+ T cells, and the development of TRP2-specific CD8+ T cells were then monitored over time. RESULTS: Vaccination led to durable antitumor immunity against PD1/Brafi-resistant melanomas in both single lesion and multifocal disease models, and it sensitized PD1-resistant melanomas to salvage therapy with αPD1. The therapeutic efficacy of the vaccine was associated with host skin-resident cells, the induction of a systemic, broadly reactive IFNγ+CD8+ T cell repertoire, increased frequencies of CD8+ TIL and reduced levels of PD1hi/intCD8+ T cells. Extended survival was associated with improved TIL functionality, exemplified by the presence of enhanced levels of IFNγ+CD8+ TIL and IL2+CD4+ TIL. CONCLUSIONS: These data support the use of a novel genetic vaccine for the effective treatment of localized or multifocal melanoma refractory to conventional αPD1-based and/or Brafi-based (immune)therapy.

Extracellular ATP and IL-23 Form a Local Inflammatory Circuit Leading to the Development of a Neutrophil-Dependent Psoriasiform Dermatitis.

Psoriasis is a chronic inflammatory skin disease dependent on the IL-23/IL-17 axis, a potent inflammatory pathway involved in pathogen clearance and autoimmunity. Several triggers have been proposed as initiators for psoriasis, including alarmins such as adenosine triphosphate. However, the role of alarmins in psoriasis pathogenesis and cutaneous inflammation has not been well addressed. Studies show that signaling through the P2X7 receptor (P2X7R) pathway underlies the development of psoriasiform inflammation. In this regard, psoriasiform dermatitis induced by IL-23 is dependent on P2X7R signaling. Furthermore, direct activation of the P2X7R is sufficient to induce a well-characterized psoriasiform dermatitis. Mechanistic studies determined that P2X7R-induced inflammation is largely dependent on the IL-1ß/NLRP3 inflammasome pathway and neutrophils. In conclusion, this work provides basic mechanistic insight into local inflammatory circuits induced after purinergic P2X7R signaling that are likely involved in the pathogenesis of many inflammatory diseases, such as psoriasis.

Tumor-derived high-mobility group box 1 and thymic stromal lymphopoietin are involved in modulating dendritic cells to activate T regulatory cells in a mouse model.

High-mobility group box 1 (HMGB1) is involved in the tumor-associated activation of regulatory T cells (Treg), but the mechanisms remain unknown. In a mouse tumor model, silencing HMGB1 in tumor cells or inhibiting tumor-derived HMGB1 not only dampened the capacity of tumor cells to produce thymic stromal lymphopoietin (TSLP), but also aborted the tumor-associated modulation of Treg-activating DC. Tumor-derived HMGB1 triggered the production of TSLP by tumor cells. Importantly, both tumor-derived HMGB1 and TSLP were necessary for modulating DC to activate Treg in a TSLP receptor (TSLPR)-dependent manner. In the therapeutic model, intratumorally inhibiting tumor-derived HMGB1 (causing downstream loss of TSLP production) attenuated Treg activation, unleashed tumor-specific CD8 T cell responses, and elicited CD8α+/CD103+DC- and T cell-dependent antitumor activity. These results suggest a new pathway for the activation of Treg involving in tumor-derived HMGB1 and TSLP, and have important implications for incorporating HMGB1 inhibitors into cancer immunotherapy.

Topical electrophilic nitro-fatty acids potentiate cutaneous inflammation.

Endogenous electrophilic fatty acids mediate anti-inflammatory responses by modulating metabolic and inflammatory signal transduction and gene expression. Nitro-fatty acids and other electrophilic fatty acids may thus be useful for the prevention and treatment of immune-mediated diseases, including inflammatory skin disorders. In this regard, subcutaneous (SC) injections of nitro oleic acid (OA-NO2), an exemplary nitro-fatty acid, inhibit skin inflammation in a model of allergic contact dermatitis (ACD). Given the nitration of unsaturated fatty acids during metabolic and inflammatory processes and the growing use of fatty acids in topical formulations, we sought to further study the effect of nitro-fatty acids on cutaneous inflammation. To accomplish this, the effect of topically applied OA-NO2 on skin inflammation was evaluated using established murine models of contact hypersensitivity (CHS). In contrast to the effects of subcutaneously injected OA-NO2, topical OA-NO2 potentiated hapten-dependent inflammation inducing a sustained neutrophil-dependent inflammatory response characterized by psoriasiform histological features, increased angiogenesis, and an inflammatory infiltrate that included neutrophils, inflammatory monocytes, and γδ T cells. Consistent with these results, HPLC-MS/MS analysis of skin from psoriasis patients displayed a 56% increase in nitro-conjugated linoleic acid (CLA-NO2) levels in lesional skin compared to non-lesional skin. These results suggest that nitro-fatty acids in the skin microenvironment are products of cutaneous inflammatory responses and, in high local concentrations, may exacerbate inflammatory skin diseases.

Intratumoral delivery of tumor antigen-loaded DC and tumor-primed CD4+ T cells combined with agonist α-GITR mAb promotes durable CD8+ T-cell-dependent antitumor immunity.

The progressive tumor microenvironment (TME) coordinately supports tumor cell expansion and metastasis, while it antagonizes the survival and (poly-)functionality of antitumor T effector cells. There remains a clear need to develop novel therapeutic strategies that can transform the TME into a pro-inflammatory niche that recruits and sustains protective immune cell populations. While intravenous treatment with tumor-primed CD4+ T cells combined with intraperitoneal delivery of agonist anti-glucocorticoid-induced TNF receptor (α-GITR) mAb results in objective antitumor responses in murine early stage disease models, this approach is ineffective against more advanced tumors. Further subcutaneous co-administration of a vaccine consisting of tumor antigen-loaded dendritic cells (DC) failed to improve the antitumor efficacy of this approach. Remarkably, these same three therapeutic agents elicited significant antitumor benefits when the antitumor CD4+ T cells and tumor antigen-loaded DC were co-injected directly into tumors along with intratumoral or intraperitoneal delivery of α-GITR mAb. This latter protocol induced the production of an array of antitumor cytokines and chemokines within the TME, supporting increased tumor-infiltration by antitumor CD8+ T cells capable of mediating tumor regression and extended overall survival.

Genetic vaccines to potentiate the effective CD103+ dendritic cell-mediated cross-priming of antitumor immunity.

The development of effective cancer vaccines remains an urgent, but as yet unmet, clinical need. This deficiency is in part due to an incomplete understanding of how to best invoke dendritic cells (DC) that are crucial for the induction of tumor-specific CD8(+) T cells capable of mediating durable protective immunity. In this regard, elevated expression of the transcription factor X box-binding protein 1 (XBP1) in DC appears to play a decisive role in promoting the ability of DC to cross-present Ags to CD8(+) T cells in the therapeutic setting. Delivery of DNA vaccines encoding XBP1 and tumor Ag to skin DC resulted in increased IFN-α production by plasmacytoid DC (pDC) from skin/tumor draining lymph nodes and the cross-priming of Ag-specific CD8(+) T cell responses associated with therapeutic benefit. Antitumor protection was dependent on cross-presenting Batf3(+) DC, pDC, and CD8(+) T cells. CD103(+) DC from the skin/tumor draining lymph nodes of the immunized mice appeared responsible for activation of Ag-specific naive CD8(+) T cells, but were dependent on pDC for optimal effectiveness. Similarly, human XBP1 improved the capacity of human blood- and skin-derived DC to activate human T cells. These data support an important intrinsic role for XBP1 in DC for effective cross-priming and orchestration of Batf3(+) DC-pDC interactions, thereby enabling effective vaccine induction of protective antitumor immunity.