Immunogenic cell death is characterized by the early surface exposure of chaperones including calreticulin and HSPs, which affect dendritic cell (DC) maturation and the uptake and presentation of tumor antigens. It has also been shown that it is characterized by the late release of high mobility group box 1 (HMGB1), which acts through Toll-like receptor 4 (TLR4) and augments the presentation of antigens from dying tumor cells to DCs. Most of the data on immunogenic tumor cell death were obtained using mouse models. In this study, we investigated the capacity of clinically used chemotherapeutics to induce immunogenic cell death in human tumor cell lines and primary tumor cells. We found that only anthracyclines induced a rapid translocation of calreticulin, HSP70, and HSP90 to the cell surface and the release of HMGB1 12 hours after the treatment. The interaction of immature DCs with immunogenic tumor cells led to an increased tumor cell uptake and induces moderate phenotypic maturation of DCs. Killed tumor cell–loaded DCs efficiently stimulated tumor-specific IFN-γ–producing T cells. DCs pulsed with killed immunogenic tumor cells also induced significantly lower numbers of regulatory T cells than those pulsed with nonimmunogenic tumor cells. These data indicate that human prostate cancer, ovarian cancer, and acute lymphoblastic leukemia cells share the key features of immunogenic cell death with mice tumor cells. These data also identify anthracyclines as anticancer drugs capable of inducing immunogenic cell death in sensitive human tumor cells. Cancer Res; 71(14); 4821–33. ©2011 AACR.

Human papillomavirus (HPV) infection is one of the most important etiologic causes of oropharyngeal head and neck squamous cell carcinoma (HNSCC). Patients with HPV-positive HNSCC were reported to have a better clinical outcome than patients with HPV-negative cancers. However, little is known about the possible causes of different clinical outcomes. In this study, we analyzed a detailed immune profile of tumor samples from HNSCC patients with respect to their HPV status. We analyzed the characteristics of immune cell infiltrates, including the frequency and distribution of antigen-presenting cells and naïve, regulatory and effector T cells and the cytokine and chemokine levels in tumor tissue. There was a profound difference in the extent and characteristics of intratumoral immune cell infiltrates in HNSCC patients based on their HPV status. In contrast to HPV-negative tumor tissues, HPV-positive tumor samples showed significantly higher numbers of infiltrating IFNγ+ CD8+ T lymphocytes, IL-17+ CD8...

Recent studies have identified molecular events characteristic of immunogenic cell death (ICD), including surface exposure of calreticulin (CRT), the heat shock proteins HSP70 and HSP90, the release of high‐mobility group box protein 1 (HMGB1) and the release of ATP from dying cells. We investigated the potential of high hydrostatic pressure (HHP) to induce ICD in human tumor cells. HHP induced the rapid expression of HSP70, HSP90 and CRT on the cell surface. HHP also induced the release of HMGB1 and ATP. The interaction of dendritic cells (DCs) with HHP‐treated tumor cells led to a more rapid rate of DC phagocytosis, upregulation of CD83, CD86 and HLA‐DR and the release of interleukin IL‐6, IL‐12p70 and TNF‐α. DCs pulsed with tumor cells killed by HHP induced high numbers of tumor‐specific T cells. DCs pulsed with HHP‐treated tumor cells also induced the lowest number of regulatory T cells. In addition, we found that the key features of the endoplasmic reticulum stress‐mediated apoptotic pathway, such as reactive oxygen species production, phosphorylation of the translation initiation factor eIF2α and activation of caspase‐8, were activated by HHP treatment. Therefore, HHP acts as a reliable and potent inducer of ICD in human tumor cells.

Background Standard treatment of oropharyngeal squamous cell carcinoma (OPSCC) is associated with high morbidity, whereas immunotherapeutic approaches using PD-1:PD-L1 checkpoint blockade only show moderate response rates in OPSCC patients. Therefore, a better stratification of patients and the development of novel therapeutic protocols are crucially needed. The importance of tumor-infiltrating B cells (TIL-Bs) in shaping antitumor immunity remains unclear; therefore, we analyzed frequency, phenotype, prognostic value and possible roles of TIL-Bs in OPSCC. Methods We utilized transcriptomic analysis of immune response-related genes in 18 OPSCC samples with respect to human papillomavirus (HPV) status. The density and localization of CD20⁺, CD8⁺ and DC-LAMP⁺ cells were subsequently analyzed in 72 tissue sections of primary OPSCC samples in relation to patients’ prognosis. The immunohistochemical approach was supplemented by flow cytometry-based analysis of phenotype and functionality of TIL-Bs in freshly resected primary OPSCC tissues. Results We observed significantly higher expression of B cell-related genes and higher densities of CD20⁺ B cells in HPV-associated OPSCC samples. Interestingly, CD20⁺ TIL-Bs and CD8⁺ T cells formed non-organized aggregates with interacting cells within the tumor tissue. The densities of both intraepithelial CD20⁺ B cells and B cell/CD8⁺ T cell interactions showed prognostic significance, which surpassed HPV positivity and CD8⁺ TIL density in stratification of OPSCC patients. High density of TIL-Bs was associated with an activated B cell phenotype, high CXCL9 production and high levels of tumor-infiltrating CD8⁺ T cells. Importantly, the abundance of direct B cell/CD8⁺ T cell interactions positively correlated with the frequency of HPV16-specific CD8⁺ T cells, whereas the absence of B cells in tumor-derived cell cultures markedly reduced CD8⁺ T cell survival. Conclusions Our results indicate that high abundance of TIL-Bs and high density of direct B cell/CD8⁺ T cell interactions can predict patients with excellent prognosis, who would benefit from less invasive treatment. We propose that in extensively infiltrated tumors, TIL-Bs might recruit CD8⁺ T cells via CXCL9 and due to a highly activated phenotype contribute by secondary costimulation to the maintenance of CD8⁺ T cells in the tumor microenvironment.

Intratumoral tertiary lymphoid structures (TLSs) have been associated with improved outcome in various cohorts of patients with cancer, reflecting their contribution to the development of tumor-targeting immunity. Here, we demonstrate that high-grade serous ovarian carcinoma (HGSOC) contains distinct immune aggregates with varying degrees of organization and maturation. Specifically, mature TLSs (mTLS) as forming only in 16% of HGSOCs with relatively elevated tumor mutational burden (TMB) are associated with an increased intratumoral density of CD8⁺ effector T (T_EFF) cells and TIM3⁺PD1⁺, hence poorly immune checkpoint inhibitor (ICI)-sensitive, CD8⁺ T cells. Conversely, CD8⁺ T cells from immunologically hot tumors like non-small cell lung carcinoma (NSCLC) are enriched in ICI-responsive TCF1⁺ PD1⁺ T cells. Spatial B-cell profiling identifies patterns of in situ maturation and differentiation associated with mTLSs. Moreover, B-cell depletion promotes signs of a dysfunctional CD8⁺ T cell compartment among tumor-infiltrating lymphocytes from freshly isolated HGSOC and NSCLC biopsies. Taken together, our data demonstrate that – at odds with NSCLC – HGSOC is associated with a low density of follicular helper T cells and thus develops a limited number of mTLS that might be insufficient to preserve a ICI-sensitive TCF1⁺PD1⁺ CD8⁺ T cell phenotype. These findings point to key quantitative and qualitative differences between mTLSs in ICI-responsive vs ICI-irresponsive neoplasms that may guide the development of alternative immunotherapies for patients with HGSOC.

Purpose:In multiple oncological settings, expression of the co-inhibitory ligand PD-L1 by malignant cells and tumor infiltration by immune cells expressing co-inhibitory receptors such as PD-1, CTLA4, LAG-3 or TIM-3 conveys prognostic or predictive information. Conversely, the impact of these features of the tumor microenvironment on disease outcome amongst high-grade serous carcinoma (HGSC) patients remains controversial. Experimental Design: We harnessed a retrospective cohort of 80 chemotherapy-naïve HGSC patients to investigate PD-L1 expression and tumor infiltration by CD8⁺ T cells, CD20⁺ B cells, DC-LAMP⁺ dendritic cells as well as by PD-1⁺, CTLA4⁺, LAG-3⁺ and TIM-3⁺ cells in relation with prognosis and function orientation of the tumor microenvironment. Immunohistochemical data were complemented with transcriptomic and functional studies on a second prospective cohort of freshly resected HGSC samples. In silico analysis of publicly available RNA expression data from 308 HGSC samples was used as a confirmatory approach. Results: High levels of PD-L1 and high densities of PD-1⁺ cells in the microenvironment of HGSCs were strongly associated with an immune contexture characterized by a robust T_H1 polarization and cytotoxic orientation that enabled superior clinical benefits. Moreover, PD-1⁺TIM-3⁺CD8⁺ T cells presented all features of functional exhaustion and correlated with poor disease outcome. However, while PD-L1 levels and tumor infiltration by TIM-3⁺ cells improved patient stratification based on the intratumoral abundance of CD8⁺ T cells, the amount of PD-1⁺ cells failed to do so. Conclusion: Our data indicate that PD-L1 and TIM-3 constitute prognostically relevant biomarkers of active and suppressed immune responses against HGSC, respectively.