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T-cell-mediated anti-tumoral responses may have significant clinical relevance as a biomarker for response to immunotherapy. The value of peripheral blood pre-existing tumor antigen-specific T cells (PreI + ) as a predictive immunotherapy biomarker in NSCLC patients was investigated, along with the frequency of various circulating immune cells. Fifty-two treatment-naïve, stage III/IV NSCLC patients, treated with front-line immune checkpoint inhibitors (ICI)-containing regimens were enrolled. PreI was calculated as the percentages of CD3 + IFNγ + cells after in vitro co-cultures of PBMCs with peptides against four different Tumor-Associated Antigens (TAA). Immunophenotyping of peripheral blood immune cells was performed using multicolor flow cytometry. PreI + T cells were detected in 44% of patients. Median overall survival (OS) was significantly higher in PreI + patients compared to PreI - patients (not reached vs. 321 days, respectively; p = 0.014). PreI + patients had significantly higher numbers of possible exhausted CD3 + CD8 + PD-1 + cells and lower percentages of immunosuppressive Tregs compared to PreI - patients. Additionally, patients with PreI + and low numbers of peripheral blood M-MDSCs had a significant survival advantage compared to the rest of the patients. Thus, combining pre-existing tumor antigen-specific immunity before initiation of ICI in NSCLC patients with selected immune-suppressive cells could identify patients who have a favorable clinical outcome when treated with ICI-containing regimens.

Using next-generation sequencing (NGS), we investigated DNA mutations in the plasma tumor cell-free circulating DNA (ctDNA) of 38 patients with inoperable squamous cell head neck cancer (SCHNC) before and after the completion of chemoradiotherapy (CRT). Baseline mutations of the TP53 were recorded in 10/38 (26.3%) and persisted in 4/10 patients after CRT. ΤP53 mutations were further detected post CRT in 7/38 additional patients with undetectable mutations at baseline (overall rate 44.7%). Furthermore, 4/38 patients exhibited baseline mutations of the EGFR , AR , FGFR3 , and FBXW3, and four new gene mutations were detected after CRT ( MTOR , EGFR3 , ALK , and SF3B1) . Τ4 stage was related with a significantly higher rate of mutations ( TP53 and overall). Mutations were observed in 8/30 (26.6%) responders (complete/partial response) vs. in 6/8 (75%) of the rest of the patients ( p = 0.03). Significant poorer LRFS was noted for patients with mutations detected before and after CRT ( p = 0.02). Patients who had detectable mutations either before or after CRT had significantly worse DMFS ( p = 0.04 overall, and p = 0.02 for TP53 mutations). It was concluded that assessment of mutations before and after the end of CRT is essential to characterize patients with a high risk of locoregional recurrence or metastatic progression.

Recently, we have shown that HLA-A*02:01 and HLA-A*24:02 in de novo metastatic prostate cancer (MPCa) have an important role in disease progression. Since de novo MPCa represents a small group among patients diagnosed with prostate cancer (PCa), it was obvious to try to extend the validity of our results to larger cohorts of PCa patients. Herein, we analyzed patients irrespective of their disease status at diagnosis to include, besides patients with MPCa, those with localized PCa (LPCa). Our goal was to specify the prognostic value of HLA-A*02:01 and HLA-A*24:02 for overall survival (OS) prospectively and for early biochemical recurrence (BCR) and castrate resistance (CR) as additional clinical endpoints in a prospective/retrospective manner, to improve clinical decisions for patients covering all stages of PCa. On univariate analysis, HLA-A alleles were significantly associated as prognostic biomarkers with early BCR ( p = 0.028; HR = 1.822), OS ( p = 0.013; HR = 1.547) and showed a trend for CR ( p = 0.150; HR = 1.239). On multivariate analysis, HLA-A alleles proved to be independent prognosticators for early BCR ( p = 0.017; HR = 2.008), CR ( p = 0.005; HR = 1.615), and OS ( p = 0.002; HR = 2.063). Kaplan-Meier analyses revealed that patients belonging to the HLA-A*02:01 + HLA-A*24:02 - group progressed much faster to BCR and CR and had also shorter OS compared to HLA-A*24:02 + patients. Patients being HLA-A*02:01 - HLA-A*24:02 - exhibited varying clinical outcomes, pointing to the presence of additional HLA-A alleles with potential prognostic value. Our data underline the HLA-A alleles as valuable prognostic biomarkers for PCa that may assist with the appropriate treatment and follow-up schedule based on the risk for disease progression to avoid over-diagnosis and over-treatment.

Prostate cancer (PCa) is one of the most common male cancers worldwide and one of the deadliest if unsuccessfully treated. Τhe need for reliable, easily accessible immune-related molecular biomarkers that could be combined with clinically defined criteria, including PSA and Gleason score, to accurately predict PCa patients' clinical outcomes is emerging. Herein, we describe for the first time a blood-identified immune-related gene signature comprising eight upregulated multi-functional genes associated with poor prognosis. Next-generation sequencing (NGS) analysis of PCa patients' peripheral blood samples revealed a more than three-fold upregulation of each of the eight genes as compared to samples originating from healthy donors. The construction of gene and protein interaction networks revealed different extents of the functional implications of these genes in the regulation of cell proliferation and immune responses. Analysis of the available data from The Cancer Genome Atlas (TCGA) regarding gene expression and survival of prostate adenocarcinoma (PRAD) and pan-cancer (PANCAN) patients revealed that intra-tumoral upregulation of this eight-gene signature (8-GS) was associated with poor 5-year progression-free intervals in PCa patients, even in those with high Gleason scores, and also with an unfavorable prognosis for cancer patients irrespective of the cancer type and even in the early stages. These observations suggest that further investigation of the 8-GS prospectively in randomized clinical trials, in which clinical benefit in terms of evaluating time to disease progression can be assessed, is warranted.

HER-2/ neu is the human epidermal growth factor receptor 2, which is associated with the progression of prostate cancer (PCa). HER-2/ neu -specific T cell immunity has been shown to predict immunologic and clinical responses in PCa patients treated with HER-2/ neu peptide vaccines. However, its prognostic role in PCa patients receiving conventional treatment is unknown, and this was addressed in this study. The densities of CD8+ T cells specific for the HER-2/ neu (780-788) peptide in the peripheral blood of PCa patients under standard treatments were correlated with TGF-β/IL-8 levels and clinical outcomes. We demonstrated that PCa patients with high frequencies of HER-2/ neu (780-788) -specific CD8+ T lymphocytes had better progression-free survival (PFS) as compared with PCa patients with low frequencies. Increased frequencies of HER-2/ neu (780-788) -specific CD8+ T lymphocytes were also associated with lower levels of TGF-β and IL-8. Our data provide the first evidence of the predictive role of HER-2/ neu -specific T cell immunity in PCa.

Head and neck cancer (HNC) is a term collectively used to describe a heterogeneous group of tumors that arise in the oral cavity, larynx, nasopharynx, oropharynx, and hypopharynx, and represents the sixth most common type of malignancy worldwide. Despite advances in multimodality treatment, the disease has a recurrence rate of around 50%, and the prognosis of metastatic patients remains poor. HNCs are characterized by a high degree of genomic instability, which involves a vicious circle of accumulating DNA damage, defective DNA damage repair (DDR), and replication stress. Nonetheless, the damage that is induced on tumor cells by chemo and radiotherapy relies on defective DDR processes for a successful response to treatment, and may play an important role in the development of novel and more effective therapies. This review summarizes the current knowledge on the genes and proteins that appear to be deregulated in DDR pathways, their implication in HNC pathogenesis, and the rationale behind targeting these genes and pathways for the development of new therapies. We give particular emphasis on the therapeutic targets that have shown promising results at the pre-clinical stage and on those that have so far been associated with a therapeutic advantage in the clinical setting.

Acquired immune resistance (AIR) describes a situation in which cancer patients who initially responded clinically to immunotherapies, after a certain period of time, progress with their disease. Considering that AIR represents a feedback response of the tumor against the immune attack generated during the course of immunotherapies, it is conceivable that AIR may also occur before treatment initiation as a mechanism to escape endogenous adaptive antitumor immunity (EAAI). In the present study, we assessed the EAAI in paraffin-embedded breast primary tumor tissue samples and drew correlations with the clinical outcomes. In particular, we analyzed densities of CD8+ cells as elements mediating antitumor cytotoxicity, and of CD163+ and FoxP3+ cells as suppressor elements. We found a direct correlation between the densities of CD8+ cells and of CD163+ and/or FoxP3+ cells in the vast majority of patients' tumors. Importantly, the vast majority of patients whose tumors were overpopulated by CD8+ cells developed AIR, which was characterized by high intratumoral CD163+ and/or FoxP3+ cell densities and reduced overall survival (OS). We also showed that AIR depends on the levels of CD8+ cell-ratios in the tumor center to the invasive margin. Our data suggest that tumors develop AIR only when under a robust endogenous immune pressure.

Radiotherapy for localized prostate cancer has increased the cure and survival rates of patients. Besides its local tumoricidal effects, ionizing radiation has been linked to mechanisms leading to systemic immune activation, a phenomenon called the abscopal effect. In this study, we performed gene expression analysis on peripheral blood from prostate cancer patients obtained post- radiotherapy and showed that 6 genes, including CCR7 , FCGR2B , BTLA , CD6 , CD3D , and CD3E , were down-regulated by a range of 1.5-2.5-fold as compared to pre-radiotherapy samples. The expression of the signature consisting of these six genes was also significantly lower post- vs. pre-radiotherapy. These genes are involved in various tumor-promoting immune pathways and their down-regulation post-radiotherapy could be considered beneficial for patients. This is supported by the fact that low mRNA expression levels for the 6-gene signature in the prostate tumor tissue was linked to better survival. Importantly, we report that this 6-gene signature strongly correlated with a favorable prognosis regardless of poor standard clinicopathological parameters (i.e., Gleason score ≥ 8 and T3 (including T3a and T3b). Our pioneering data open the possibility that the 6-gene signature identified herein may have a predictive value, but this requires further long-term studies.

Head and neck cancers (HNCs) comprise a heterogeneous group of tumors that extend from the oral cavity to the upper gastrointestinal tract. The principal etiologic factors for oral tumors include tobacco smoking and alcohol consumption, while human papillomavirus (HPV) infections have been accused of a high incidence of pharyngeal tumors. Accordingly, HPV detection has been extensively used to categorize carcinomas of the head and neck. The diverse nature of HNC highlights the necessity for novel, sensitive, and precise biomarkers for the prompt diagnosis of the disease, its successful monitoring, and the timely prognosis of patient clinical outcomes. In this context, the identification of certain microRNAs (miRNAs) and/or the detection of alterations in their expression patterns, in a variety of somatic fluids and tissues, could serve as valuable biomarkers for precision oncology. In the present review, we summarize some of the most frequently studied miRNAs (including miR-21, -375, -99, -34a, -200, -31, -125a/b, -196a/b, -9, -181a, -155, -146a, -23a, -16, -29, and let-7), their role as biomarkers, and their implication in HNC pathogenesis. Moreover, we designate the potential of given miRNAs and miRNA signatures as novel diagnostic and prognostic tools for successful patient stratification. Finally, we discuss the currently ongoing clinical trials that aim to identify the diagnostic, prognostic, or therapeutic utility of miRNAs in HNC.

Radiotherapy (RT) is a therapeutic modality that aims to eliminate malignant cells through the induction of DNA damage in the irradiated tumor site. In addition to its cytotoxic properties, RT also induces mechanisms that result in the promotion of antitumor immunity both locally within the irradiation field but also at distant tumor lesions, a phenomenon that is known as the "abscopal" effect. Because the immune system is capable of sensing the effects of RT, several treatment protocols have been assessing the synergistic role of radiotherapy combined with immunotherapy, collectively referred to as radioimmunotherapy. Herein, we discuss mechanistic insights underlying RT-based immunomodulation, which also enhance our understanding of how RT regulates antitumor T-cell-mediated immunity. Such knowledge is essential for the discovery of predictive biomarkers and for the improvement of clinical trials investigating the efficacy of radio-immunotherapeutic modalities in cancer patients.

Therapeutic cancer vaccines have been at the forefront of cancer immunotherapy for more than 20 years, with promising results in phase I and-in some cases-phase II clinical trials, but with failures in large phase III studies. After dozens of clinical studies, only Dendreon's dendritic cell vaccine Sipuleucel-T has succeeded in receiving US FDA approval for the treatment of metastatic castrate-resistant prostate cancer. Although scientists working on cancer immunotherapy feel that this is an essential breakthrough for the field, they still expect that new vaccine regimens will yield better clinical benefits compared to the four months prolonged median overall survival (OS) Sipuleucel-T demonstrated in the IMPACT phase III clinical trial. Clinical development of cancer vaccines has been unsuccessful due to failures either in randomized phase II or-even worse-phase III trials. Thus, rigorous re-evaluation of these trials is urgently required in order to redefine aspects and optimize the benefits offered by therapeutic cancer vaccines. The scope of this review is to provide to the reader our thoughts on the key challenges in maximizing the therapeutic potentials of cancer vaccines, with a special focus on issues that touch upon clinical trial design., Competing Interests: The authors declare no conflict of interest.

The prognostic value of human leukocyte antigen (HLA) class I molecules in prostate cancer (PCa) remains unclear. Herein, we investigated the prognostic relevance of the most frequently expressed HLA-A alleles in Greece (A*02:01 and HLA-A*24:02) in de novo metastatic hormone-sensitive PCa (mPCa), which is a rare and aggressive disease characterized by a rapid progression to castration-resistance (CR) and poor overall survival (OS), contributing to almost 50% of PCa-related deaths. We identified 56 patients who had either progressed to CR (these patients were retrospectively analyzed for the time to the progression of CR and prospectively for OS) or had at least three months' follow-up postdiagnosis without CR progression and, thus, were prospectively analyzed for both CR and OS. Patients expressing HLA-A*02:01 showed poor clinical outcomes vs. HLA-A*02:01 - negative patients. HLA-A*24:02 - positive patients progressed slower to CR and had increased OS. Homozygous HLA-A*02:01 patients progressed severely to CR, with very short OS. Multivariate analyses ascribed to both HLA alleles significant prognostic values for the time to progression (TTP) to CR and OS. The presence of HLA-A*02:01 and HLA-A*24:02 alleles in de novo mPCa patients are significantly and independently associated with unfavorable or favorable clinical outcomes, respectively, suggesting their possible prognostic relevance for treatment decision-making in the context of precision medicine.