Analyses of Pretherapy Peripheral Immunoscore and Response to Vaccine Therapy

Peripheral immune biomarkers for immune checkpoint inhibition of solid tumours

BACKGROUND

With the rapid adoption of immunotherapy for the treatment of cancer comes the pressing need for readily accessible biomarkers to guide immunotherapeutic strategies and offer insights into outcomes with specific treatments. Regular sampling of solid tumour tissues outside of melanoma for immune monitoring is not often feasible; conversely, routine, frequent interrogation of circulating immune biomarkers is entirely possible. As immunotherapies and immune checkpoint inhibitors, in particular, are more widely used in first-line, neoadjuvant, and metastatic settings, the discovery and validation of peripheral immune biomarkers are urgently needed across solid tumour types for improved prediction and prognostication of clinical outcomes in response to immunotherapy, as well as elucidation of mechanistic underpinnings of the intervention. Careful experimental design, encompassing both retrospective and prospective studies, is required in such biomarker identification studies, and concerted efforts are essential for their advancement into clinical settings.

CONCLUSION

In this review, we summarize shared immune features between the tumour microenvironment and systemic circulation, evaluate exploratory peripheral immune biomarker studies, and discuss associations between candidate biomarkers with clinical outcomes. We also consider integration of multiple peripheral immune parameters for better prediction and prognostication and discuss considerations in study design to further evaluate the clinical utility of candidate peripheral immune biomarkers for immunotherapy of solid tumours.

HIGHLIGHTS

Peripheral immune biomarkers are critical for improved prediction and prognostication of clinical outcomes for patients with solid tumours treated with immune checkpoint inhibition. Candidate peripheral biomarkers, such as cytokines, soluble factors, and immune cells, have potential as biomarkers to guide immunotherapy of solid tumours. Multiple peripheral immune parameters may be integrated to improve prediction and prognostication. The potential of peripheral immune biomarkers to guide immunotherapy of solid tumours requires critical work in biomarker discovery, validation, and standardization.

Adjuvant nivolumab, capecitabine or the combination in patients with residual triple-negative breast cancer: the OXEL randomized phase II study

Chemotherapy and immune checkpoint inhibitors have a role in the post-neoadjuvant setting in patients with triple-negative breast cancer (TNBC). However, the effects of nivolumab, a checkpoint inhibitor, capecitabine, or the combination in changing peripheral immunoscore (PIS) remains unclear. This open-label randomized phase II OXEL study (NCT03487666) aimed to assess the immunologic effects of nivolumab, capecitabine, or the combination in terms of the change in PIS (primary endpoint). Secondary endpoints included the presence of ctDNA, toxicity, clinical outcomes at 2-years and association of ctDNA and PIS with clinical outcomes. Forty-five women with TNBC and residual invasive disease after standard neoadjuvant chemotherapy were randomized to nivolumab, capecitabine, or the combination. Here we show that a combination of nivolumab plus capecitabine leads to a greater increase in PIS from baseline to week 6 (91%) compared with nivolumab (47%) or capecitabine (53%) alone (log-rank p = 0.08), meeting the pre-specified primary endpoint. In addition, the presence of circulating tumor DNA (ctDNA) is associated with disease recurrence, with no new safety signals in the combination arm. Our results provide efficacy and safety data on this combination in TNBC and support further development of PIS and ctDNA analyses to identify patients at high risk of recurrence.

Adjuvant nivolumab, capecitabine or the combination in patients with residual triple-negative breast cancer: the OXEL randomized phase II study

Chemotherapy and immune checkpoint inhibitors have a role in the post-neoadjuvant setting in patients with triple-negative breast cancer (TNBC). However, the effects of nivolumab, a checkpoint inhibitor, capecitabine, or the combination in changing peripheral immunoscore (PIS) remains unclear. This open-label randomized phase II OXEL study (NCT03487666) aimed to assess the immunologic effects of nivolumab, capecitabine, or the combination in terms of the change in PIS (primary endpoint). Secondary endpoints include the presence of ctDNA, toxicity, clinical outcomes at 2-years and association of ctDNA and PIS with clinical outcomes. Forty-five women with TNBC and residual invasive disease after standard neoadjuvant chemotherapy were randomized to nivolumab, capecitabine, or the combination. Here we show that a combination of nivolumab plus capecitabine leads to a greater increase in PIS from baseline to week 6 (91%) compared with nivolumab (47%) or capecitabine (53%) alone (log-rank p = 0.08), meeting the pre-specified primary endpoint. In addition, the presence of circulating tumor DNA (ctDNA) was associated with disease recurrence, with no new safety signals in the combination arm. Our results provide efficacy and safety data on this combination in TNBC and support further development of PIS and ctDNA analyses to identify patients at high risk of recurrence.

Blood immune cells as potential biomarkers predicting relapse-free survival of stage III/IV resected melanoma patients treated with peptide-based vaccination and interferon-alpha

Introduction

Despite the recent approval of several therapies in the adjuvant setting of melanoma, tumor relapse still occurs in a significant number of completely resected stage III-IV patients. In this context, the use of cancer vaccines is still relevant and may increase the response to immune checkpoint inhibitors. We previously demonstrated safety, immunogenicity and preliminary evidence of clinical efficacy in stage III/IV resected melanoma patients subjected to a combination therapy based on peptide vaccination together with intermittent low-dose interferon-α2b, with or without dacarbazine preconditioning (https://www.clinicaltrialsregister.eu/ctr-search/search, identifier: 2008-008211-26). In this setting, we then focused on pre-treatment patient immune status to highlight possible factors associated with clinical outcome.

Methods

Multiparametric flow cytometry was used to identify baseline immune profiles in patients' peripheral blood mononuclear cells and correlation with the patient clinical outcome. Receiver operating characteristic curve, Kaplan-Meier survival and principal component analyses were used to evaluate the predictive power of the identified markers.

Results

We identified 12 different circulating T and NK cell subsets with significant (p ≤ 0.05) differential baseline levels in patients who later relapsed with respect to patients who remained free of disease. All 12 parameters showed a good prognostic accuracy (AUC>0.7, p ≤ 0.05) and 11 of them significantly predicted the relapse-free survival. Remarkably, 3 classifiers also predicted the overall survival. Focusing on immune cell subsets that can be analyzed through simple surface staining, three subsets were identified, namely regulatory T cells, CD56^dimCD16^- NK cells and central memory γδ T cells. Each subset showed an AUC>0.8 and principal component analysis significantly grouped relapsing and non-relapsing patients (p=0.034). These three subsets were used to calculate a combination score that was able to perfectly distinguish relapsing and non-relapsing patients (AUC=1; p=0). Noticeably, patients with a combined score ≥2 demonstrated a strong advantage in both relapse-free (p=0.002) and overall (p=0.011) survival as compared to patients with a score <2.

Discussion

Predictive markers may be used to guide patient selection for personalized therapies and/or improve follow-up strategies. This study provides preliminary evidence on the identification of peripheral blood immune biomarkers potentially capable of predicting the clinical response to combined vaccine-based adjuvant therapies in melanoma.

A Mutated Prostatic Acid Phosphatase (PAP) Peptide-Based Vaccine Induces PAP-Specific CD8+ T Cells with Ex Vivo Cytotoxic Capacities in HHDII/DR1 Transgenic Mice

BACKGROUND

Current treatments for castrate (hormone)-resistant prostate cancer (CRPC) remain limited and are not curative, with a median survival from diagnosis of 23 months. The PAP-specific Sipuleucel-T vaccine, which was approved by the FDA in 2010, increases the Overall Survival (OS) by 4 months, but is extremely expensive. We have previously shown that a 15 amino accid (AA) PAP sequence-derived peptide could induce strong immune responses and delay the growth of murine TRAMP-C1 prostate tumors. We have now substituted one amino acid and elongated the sequence to include epitopes predicted to bind to several additional HLA haplotypes. Herein, we present the immunological properties of this 42mer-mutated PAP-derived sequence (MutPAP42mer).

METHODS

The presence of PAP-135-143 epitope-specific CD8⁺ T cells in the blood of patients with prostate cancer (PCa) was assessed by flow cytometry using Dextramer™ technology. HHDII/DR1 transgenic mice were immunized with mutated and non-mutated PAP-derived 42mer peptides in the presence of CAF^®09 or CpG ODN1826 (TLR-9 agonist) adjuvants. Vaccine-induced immune responses were measured by assessing the proportion and functionality of splenic PAP-specific T cells in vitro.

RESULTS

PAP-135-143 epitope-specific CD8⁺ T cells were detected in the blood of patients with PCa and stimulation of PBMCs from patients with PCa with mutPAP42mer enhanced their capacity to kill human LNCaP PCa target cells expressing PAP. The MutPAP42mer peptide was significantly more immunogenic in HHDII/DR1 mice than the wild type sequence, and immunogenicity was further enhanced when combined with the CAF^®09 adjuvant. The vaccine induced secretory (IFNγ and TNFα) and cytotoxic CD8⁺ T cells and effector memory splenic T cells.

CONCLUSIONS

The periphery of patients with PCa exhibits immune responsiveness to the MutPAP42mer peptide and immunization of mice induces/expands T cell-driven, wild-type PAP immunity, and therefore, has the potential to drive protective anti-tumor immunity in patients with PCa.

Evaluation of Immune Infiltration Based on Image Plus Helps Predict the Prognosis of Stage III Gastric Cancer Patients with Significantly Different Outcomes in Northeastern China

Gastric cancer (GC) might have significantly different outcomes within the same AJCC/UICC-TNM stage. The purpose of this study is to help predict the different prognosis through the pattern of immune cell infiltration. We retrospectively analyzed 2605 patients who underwent radical gastrectomy in the Harbin Medical University Cancer Hospital between 2002 and 2013. For stage III with significantly different survival probability, we analyzed the relationship between immune cell surface antigen and survival in TCGA dataset. Furthermore, 200 cases in stage III GC with different survival outcomes were randomly selected for immunohistochemical verification. Image Plus software was used to evaluate the area of immune cell infiltration. We found that patients in stage III had significantly different outcomes. Bioinformatics analysis showed that there was a significant negative correlation between the expression of immune cell surface antigen and prognosis. In order to investigate whether immune infiltration can distinguish GC patients in stage III with differences in prognosis, we verified by immunohistochemistry that CD4+ T cells, CD20+ B cells, and CD177+ neutrophils infiltrated more in group B with better prognosis; CD8+ T cells, CD68+ macrophages, and CD117+ mast cells infiltrated more in group A with poor prognosis. CD117+ mast cells have the same trend of predicting significance for prognosis in the RNA and protein levels. In conclusion, patients with GC in northeastern China have significant prognostic differences only in stage III. CD117+ mast cells may be important evaluation factors in further studies of Immunoscore.

Interrogation of the cellular immunome of cancer patients with regard to the COVID-19 pandemic

While vaccines directed against the SARS-CoV-2 spike protein will have varying degrees of effectiveness in preventing SARS-CoV-2 infections, the severity of infection will be determined by multiple host factors including the ability of immune cells to lyse virus-infected cells. This review will discuss the complexity of both adaptive and innate immunomes and how a flow-based assay can detect up to 158 distinct cell subsets in the periphery. This assay has been employed to show the effect of age on differences in specific immune cell subsets, and the differences in the immunome between healthy donors and age-matched cancer patients. Also reviewed are the numerous soluble factors, in addition to cytokines, that may vary in the pathogenesis of SARS-CoV-2 infections and may also be employed to help define the effectiveness of a given vaccine or other antiviral agents. Various steroids have been employed in the management of autoimmune adverse events in cancer patients receiving immunotherapeutics and may be employed in the management of SARS-CoV-2 infections. The influence of steroids on multiple immune cells subsets will also be discussed.

Immune Activation in Patients with Locally Advanced Cervical Cancer Treated with Ipilimumab Following Definitive Chemoradiation (GOG-9929)

PURPOSE

A phase I clinical trial (GOG-9929) examined the safety and efficacy of adjuvant immune-modulation therapy with the checkpoint inhibitor ipilimumab [anti-CTL antigen-4 (anti-CTLA-4)] following chemoradiation therapy (CRT) for newly diagnosed node-positive human papillomavirus (HPV)-related cervical cancer. To better understand the mechanism of action and to identify predictive biomarkers, immunologic and viral correlates were assessed before, during, and after treatment.

PATIENTS AND METHODS

Twenty-one patients who received CRT and ≥2 doses of ipilimumab and 5 patients who received CRT only were evaluable for translational endpoints. Circulating T-cell subsets were evaluated by multiparameter flow cytometry. Cytokines were evaluated by multiplex ELISA. HPV-specific T cells were evaluated in a subset of patients by IFNγ ELISpot.

RESULTS

Expression of the activation markers ICOS and PD-1 significantly increased on T-cell subsets following CRT and were sustained or increased following ipilimumab treatment. Combined CRT/ipilimumab treatment resulted in a significant expansion of both central and effector memory T-cell populations. Genotype-specific E6/E7-specific T-cell responses increased post-CRT in 1 of 8 HPV16⁺ patients and in 2 of 3 HPV18⁺ patients. Elevation in levels of tumor-promoting circulating cytokines (TNFα, IL6, IL8) post-CRT was significantly associated with worse progression-free survival.

CONCLUSIONS

Our data indicate that CRT alone and combined with ipilimumab immunotherapy show immune-modulating activity in women with locally advanced cervical cancer and may be a promising therapeutic option for the enhancement of antitumor immune cell function after primary CRT for this population at high risk for recurrence and metastasis. Several key immune biomarkers were identified that were associated with clinical response.

Intratumoral HLA-DR-/CD33+/CD11b+ Myeloid-Derived Suppressor Cells Predict Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

Capecitabine-based neoadjuvant chemoradiation therapy (nCRT) is currently the mainstay of treatment for locally advanced rectal cancer (LARC), prior to surgical tumor removal. While response to this treatment is partial, it carries significant risk of side effects. As of today, there is no accepted model to predict tumor response, and allow for patient stratification. The level of circulating Myeloid-derived suppressor cells (MDSCs), a subpopulation of early myeloid cells (EMCs), has been shown to correlate with prognosis and response to therapy in advanced colon cancer, but their role in LARC is not clear. We sought to study the effect of intratumoral and circulating levels of different EMCs subpopulations including MDSCs on response to nCRT. We analyzed tumor, normal mucosa, and peripheral blood samples from 25 LARC patients for their different EMCs subpopulation before and after nCRT, and correlated them with degree of pathologic response, as determined postoperatively. In addition, we compared LARC patient to 10 healthy donors and 6 metastatic patients. CD33⁺HLA-DR⁻CD16⁻CD11b⁺EMCs in the circulation of LARC patients were found to inhibit T-cell activation. Furthermore, elevated levels of CD33⁺HLA-DR⁻ myeloid cells were found in the tumor relative to normal mucosa, but not in the circulation when compared to healthy subjects. Moreover, intratumoral, but not circulating levels of MDSCs correlated with clinical stage and response to therapy in patients treated with nCRT, with high levels of MDSCs significantly predicting poor response to nCRT. Importantly, therapy by itself, had significant differential effects on MDSC levels, leading to increased circulating MDSCs, concomitantly with decreasing intratumoral MDSCs. Our results suggest that high levels of intratumoral, but not circulating MDSCs may confer drug resistance due to immunomodulatory effects, and serve as a biomarker for patient stratification and decision-making prior to nCRT.

A randomized phase 2 trial of pembrolizumab versus pembrolizumab and acalabrutinib in patients with platinum-resistant metastatic urothelial cancer

Background

Inhibition of the programmed cell death protein 1 (PD‐1) pathway has demonstrated clinical benefit in metastatic urothelial cancer (mUC); however, response rates of 15% to 26% highlight the need for more effective therapies. Bruton tyrosine kinase (BTK) inhibition may suppress myeloid‐derived suppressor cells (MDSCs) and improve T‐cell activation.

Methods

The Randomized Phase 2 Trial of Acalabrutinib and Pembrolizumab Immunotherapy Dual Checkpoint Inhibition in Platinum‐Resistant Metastatic Urothelial Carcinoma (RAPID CHECK; also known as ACE‐ST‐005) was a randomized phase 2 trial evaluating the PD‐1 inhibitor pembrolizumab with or without the BTK inhibitor acalabrutinib for patients with platinum‐refractory mUC. The primary objectives were safety and objective response rates (ORRs) according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included progression‐free survival (PFS) and overall survival (OS). Immune profiling was performed to analyze circulating monocytic MDSCs and T cells.

Results

Seventy‐five patients were treated with pembrolizumab (n = 35) or pembrolizumab plus acalabrutinib (n = 40). The ORR was 26% with pembrolizumab (9% with a complete response [CR]) and 20% with pembrolizumab plus acalabrutinib (10% with a CR). The grade 3/4 adverse events (AEs) that occurred in ≥15% of the patients were anemia (20%) with pembrolizumab and fatigue (23%), increased alanine aminotransferase (23%), urinary tract infections (18%), and anemia (18%) with pembrolizumab plus acalabrutinib. One patient treated with pembrolizumab plus acalabrutinib had high MDSCs at the baseline, which significantly decreased at week 7. Overall, MDSCs were not correlated with a clinical response, but some subsets of CD8+ T cells did increase during the combination treatment.

Conclusions

Both treatments were generally well tolerated, although serious AE rates were higher with the combination. Acalabrutinib plus pembrolizumab did not improve the ORR, PFS, or OS in comparison with pembrolizumab alone in mUC. Baseline and on‐treatment peripheral monocytic MDSCs were not different in the treatment cohorts. Proliferating CD8+ T‐cell subsets increased during treatment, particularly in the combination cohort. Ongoing studies are correlating these peripheral immunome findings with tissue‐based immune cell infiltration.

In this randomized phase 2 study of metastatic urothelial cancer, a combination of pembrolizumab and a Bruton tyrosine kinase inhibitor (acalabrutinib) does not improve clinical outcomes in comparison with pembrolizumab alone. Comprehensive flow cytometry is used to evaluate circulating immune cells during treatment.

Predictive Value of Postoperative Peripheral CD4+ T Cells Percentage in Stage I-III Colorectal Cancer: A Retrospective Multicenter Cohort Study of 1028 Subjects

Objective

Association of postoperative peripheral CD4+ T cells percentage and recurrence in colorectal cancer (CRC) remains to be explored. Therefore, we aimed to investigate the association between the postoperative peripheral CD4+ T cells percentage and recurrence in CRC patients.

Patients and Methods

Consecutive stage I–III CRC patients without neoadjuvant treatment undergoing curative resection from January 2010 to July 2016 were identified in two Chinese centers. The association between the postoperative CD4+ T cells percentage, measured within 12 weeks after surgery, and recurrence-free survival (RFS) was analyzed.

Results

A total of 1028 patients were identified (training set: 913 patients, validation set: 115 patients). In the training set, the 5-year RFS rate of the 441 patients with abnormal postoperative CD4+ T cells percentage was significantly lower than that of those with normal percentage (70.3% [95% CI 65.7–75.2%] vs 77.6% [95% CI 73.7–81.7%] and unadjusted hazard ratio [HR] 1.36 [95% CI 1.04–1.78], P=0.02). The result was confirmed in the validation set. Multivariable Cox regression analysis demonstrated that the association of postoperative CD4+ T cells percentage with 5-year RFS was independent both in the training and validation sets. In propensity score matching analysis, patients with normal postoperative CD4+ T cells percentage were found to have a favourable response to adjuvant chemotherapy (HR 0.29 [95% CI 0.12–0.72], P=0.008).

Conclusion

Postoperative peripheral CD4+ T cells percentage is a predictive biomarker for RFS in patients with CRC, which can identify those who will benefit from adjuvant chemotherapy.

Immunoscore: a novel prognostic tool. Association with clinical outcome, response to treatment and survival in several malignancies

The predictive accuracy of the traditional staging system for cancer, the American Joint Committee on Cancer/Union Internationale Centre le Cancer (AJCC/UICC) classification of malignant tumors, is based on disease progression as a tumor cell-autonomous process, regardless the effects of the host immune response. The natural history of a tumor includes different phases of growth, migration and invasion. During these phases, tumor cells interact with their microenvironment and are influenced by signals from stromal, endothelial, inflammatory and immune cells. Indeed, tumors are often infiltrated by defensive cells such as lymphocytes, macrophages or mast cells and it has been shown extensively that lymphocytes may control cancer outcome, as evidenced in several human malignancies. Increasing evidence suggests that cancer progression is strongly influenced by host immune response, which is represented by immune cell infiltrates. The T-lymphocyte-based immunoscore (IS) has proved to be a prognostic factor in human malignancies such as colon, pancreas and lung cancer, hepatocellular carcinoma, melanoma and even brain metastases. Although the IS was initially established to evaluate the prognosis of stage I/II/III colon cancer patients, its association with clinical outcomes and survival has been shown in other malignancies. The aim of this review is to analyze the association of IS with prognosis, survival and response to therapy in different tumor types.

Clinical Relevance and Immunosuppressive Pattern of Circulating and Infiltrating Subsets of Myeloid-Derived Suppressor Cells (MDSCs) in Epithelial Ovarian Cancer

Myeloid-derived suppressor cells (MDSCs) expansion is a hallmark of cancer. Three major MDSC subsets defined as monocytic (M)-MDSCs, polymorphonuclear (PMN)-MDSCs and early stage (e)MDSCs can be revealed in human diseases. However, the clinical relevance and immunosupressive pattern of these cells in epithelial ovarian cancer (EOC) are unknown. Therefore, we performed a comprehensive analysis of each MDSC subset and immunosupressive factors in the peripheral blood (PB), peritoneal fluid (PF), and the tumor tissue (TT) samples from EOC and integrated this data with the patients' clinicopathological characteristic. MDSCs were analyzed using multicolor flow cytometry. Immunosuppressive factors analysis was performed with ELISA and qRT-PCR. The level of M-MDSCs in the PB/PF/TT of EOC was significantly higher than in healthy donors (HD); frequency of PMN-MDSCs was significantly greater in the TT than in the PB/PF and HD; while the level of eMDSCs was greater in the PB compared with the PF and HD. Elevated abundance of tumor-infiltrating M-MDSCs was associated with advanced stage and high grade of EOC. An analysis of immunosuppressive pattern showed significantly increased blood-circulating ARG/IDO/IL-10-expressing M- and PMN-MDSCs in the EOC patients compared with HD and differences in the accumulation of these subsets in the three tumor immune microenvironments (TIME). This accumulation was positively correlated with levels of TGF-β and ARG1 in the plasma and PF. Low level of blood-circulating and tumor-infiltrating M-MDSCs, but neither PMN-MDSCs nor eMDSCs was strongly associated with prolonged survival in ovarian cancer patients. Our results highlight M-MDSCs as the subset with potential the highest clinical significance.

Failed immune responses across multiple pathologies share pan-tumor and circulating lymphocytic targets

Rationale Tumor infiltrating lymphocytes are widely associated with positive outcomes, yet carry key indicators of a systemic failed immune response against unresolved cancer. Cancer immunotherapies can reverse their tolerance phenotypes, while preserving tumor-reactivity and neoantigen-specificity shared with circulating immune cells. Objectives We performed comprehensive transcriptomic analyses to identify gene signatures common to circulating and tumor infiltrating lymphocytes in the context of clear cell renal cell carcinoma. Modulated genes also associated with disease outcome were validated in other cancer types. Findings Using bioinformatics, we identified practical diagnostic markers and actionable targets of the failed immune response. On circulating lymphocytes, three genes, LEF1, FASLG, and MMP9, could efficiently stratify patients from healthy control donors. From their associations with resistance to cancer immunotherapies and microbial infections, we uncovered not only pan-cancer, but pan-pathology failed immune response profiles. A prominent lymphocytic matrix metallopeptidase cell migration pathway, is central to a panoply of diseases and tumor immunogenicity, correlates with multi-cancer recurrence, and identifies a feasible, non-invasive approach to pan-pathology diagnoses. Conclusions The non-invasive differently expressed genes we have identified warrant future investigation towards the development of their potential in precision diagnostics and precision pan-disease immunotherapeutics.

Dissecting the Immune Landscape of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a molecularly heterogeneous hematological malignancy with variable response to treatment. Recurring cytogenetic abnormalities and molecular lesions identify AML patient subgroups with different survival probabilities; however, 50⁻70% of AML cases harbor either normal or risk-indeterminate karyotypes. The discovery of better biomarkers of clinical success and failure is therefore necessary to inform tailored therapeutic decisions. Harnessing the immune system against cancer with programmed death-1 (PD-1)-directed immune checkpoint blockade (ICB) and other immunotherapy agents is an effective therapeutic option for several advanced malignancies. However, durable responses have been observed in only a minority of patients, highlighting the need to gain insights into the molecular features that predict response and to also develop more effective and rational combination therapies that address mechanisms of immune evasion and resistance. We will review the state of knowledge of the immune landscape of AML and identify the broad opportunity to further explore this incompletely characterized space. Multiplexed, spatially-resolved immunohistochemistry, flow cytometry/mass cytometry, proteomic and transcriptomic approaches are advancing our understanding of the complexity of AML-immune interactions and are expected to support the design and expedite the delivery of personalized immunotherapy clinical trials.

Blood-based analyses of cancer: Circulating myeloid-derived suppressor cells - is a new era coming?

Progress in cancer treatment made by the beginning of the 21st century has shifted the paradigm from one-size-fits-all to tailor-made treatment. The popular vision, to study solid tumors through the relatively noninvasive sampling of blood, is one of the most thrilling and rapidly advancing fields in global cancer diagnostics. From this perspective, immune-cell analysis in cancer could play a pivotal role in oncology practice. This approach is driven both by rapid technological developments, including the analysis of circulating myeloid-derived suppressor cells (cMDSCs), and by the increasing application of (immune) therapies, the success or failure of which may depend on effective and timely measurements of relevant biomarkers. Although the implementation of these powerful noninvasive diagnostic capabilities in guiding precision cancer treatment is poised to change the ways in which we select and monitor cancer therapy, challenges remain. Here, we discuss the challenges associated with the analysis and clinical aspects of cMDSCs and assess whether the problems in implementing tumor-evolution monitoring as a global tool in personalized oncology can be overcome.

HER2-Based Immunotherapy for Breast Cancer

Resistance to therapies and disease recurrences after surgery or treatment are common challenges in breast cancer management in clinic. Active immunotherapy using human epidermal growth factor receptor 2 (HER2)-targeted vaccines represents an attractive option in combating breast cancer. Different HER2-derived vaccines have been developed over the years. Many clinical trials have been carried out in evaluating HER2-based vaccines. The authors reviewed current literature on HER2-based vaccines in clinical trials. The trials covered in this mini-review represent some of the major trials published in the past 20 years regarding the clinical use and test of HER2 vaccines. Their focus is on trials using HER2 peptide vaccines as the majority of clinical trials initiated or published used HER2 peptide-based vaccines. Findings from combination therapy trials of HER2 peptide vaccines with other treatment modalities are also presented.

Immunotherapy for metastatic prostate cancer: immuno-cold or the tip of the iceberg?

PURPOSE OF REVIEW

Metastatic castration-resistant prostate cancer is in critical need of new and innovative treatment strategies. Since the approval of sipuleucel-T, the investigatory climate of prostate cancer immunotherapy has been rapidly evolving with promising developments in vaccine and immune checkpoint therapies.

RECENT FINDINGS

Sipuleucel-T remains the first and only therapeutic cancer vaccine approved for its survival benefit in metastatic castration-resistant prostate cancer. Additional cancer vaccines are currently being evaluated, with the most promising being a peptide vaccine encoding prostate-specific antigen, known as prostate-specific antigen-TRICOM. Emerging data supports combinatorial strategies for vaccine therapy and a potential role for implementation in earlier stages of advanced disease. Immune checkpoint therapies have demonstrated limited success in prostate cancer with negative late phase trials for ipilimumab monotherapy and discouraging early phase results for programmed cell death protein 1 blockade. Novel immune-modulatory targets and rational combination strategies aim to produce more favorable results. Recent progress has been made to determine biologic predictors for response and toxicity in prostate cancer immunotherapy aiming to improve patient selection and safety.

SUMMARY

Steady progress is anticipated in the field of prostate cancer immunotherapy including ongoing development of novel cancer vaccines, immune checkpoint therapies, and combinatorial strategies.

Developing anti-HER2 vaccines: Breast cancer experience

Breast cancer accounts for more than one million new cases annually and is the leading cause of death in women globally. HER2 overexpression induces cellular and humoral immune responses against the HER2 protein and is associated with higher tumor proliferation rates. Trastuzumab-based therapies are effectively and widely used as standard of care in HER2-amplified/overexpressed breast cancer patients; one cited mechanism of action is the induction of passive immunity and antibody-dependent cellular cytotoxicity against malignant breast cancer cells. These findings drove the efforts to generate antigen-specific immunotherapy to trigger the patient's immune system to target HER2-overexpressing tumor cells, which led to the development of various vaccines against the HER2 antigen. This article discusses the various anti-HER2 vaccine formulations and strategies and their potential role in the metastatic and adjuvant settings.

Correlates of immune and clinical activity of novel cancer vaccines

Cancer vaccines are solely meant to amplify the pool of type 1 cytokine oriented CD4+ and CD8+ T cells that recognize tumor antigen and ultimately foster control and destruction of a growing tumor. They are not designed to deal with all aspects of immune ignorance, exclusion, suppression and escape that are generally in place in patients with cancer and may prevent the T cells to enter the tumor or to exert their effector function. This simple fact prompted for a reappraisal of the many recent trials in which therapeutic cancer vaccines have been examined as monotherapy. In this review, I focus on trials examining therapeutic cancer vaccines at different stages of existing disease. The analysis of vaccine-induced immune responses and clinical activity of therapeutic cancer vaccines revealed four levels of evidence for vaccine efficacy. The lowest levels, reflect the many trials in which the strength of the tumor-reactive T cell response of vaccinated patients is associated with better clinical outcome or change in tumor marker. The highest levels indicate occasional regressions of tumors and metastases after vaccination or reflect a stronger clinical impact of vaccine in a randomized trial. A whole series of trials in which vaccine-induced tumor immunity correlates with the clinical impact of cancer vaccines in premalignant diseases, settings of low tumor burden or tumor regressions in patients with cancer, form an attest to the fact that cancer vaccines work. While the current number of true clinical responders in each cancer trial is too low for firm conclusions on immune correlates of clinical reactivity in cancer, extrapolation of the results from vaccinated patients with pre-cancers suggest a requirement of broad type 1 T cell reactivity.

An NK cell line (haNK) expressing high levels of granzyme and engineered to express the high affinity CD16 allele

Natural killer (NK) cells are known to play a role in mediating innate immunity, in enhancing adaptive immune responses, and have been implicated in mediating anti-tumor responses via antibody-dependent cell-mediated cytotoxicity (ADCC) by reactivity of CD16 with the Fc region of human IgG1 antibodies. The NK-92 cell line, derived from a lymphoma patient, has previously been well characterized and adoptive transfer of irradiated NK-92 cells has demonstrated safety and shown preliminary evidence of clinical benefit in cancer patients. The NK-92 cell line, devoid of CD16, has now been engineered to express the high affinity (ha) CD16 V158 FcγRIIIa receptor, as well as engineered to express IL-2; IL-2 has been shown to replenish the granular stock of NK cells, leading to enhanced perforin- and granzyme-mediated lysis of tumor cells. The studies reported here show high levels of granzyme in haNK cells, and demonstrate the effects of irradiation of haNK cells on multiple phenotypic markers, viability, IL-2 production, and lysis of a spectrum of human tumor cells. Studies also compare endogenous irradiated haNK lysis of tumor cells with that of irradiated haNK-mediated ADCC using cetuximab, trastuzumab and pertuzumab monoclonal antibodies. These studies thus provide the rationale for the potential use of irradiated haNK cells in adoptive transfer studies for a range of human tumor types. Moreover, since only approximately 10% of humans are homozygous for the high affinity V CD16 allele, these studies also provide the rationale for the use of irradiated haNK cells in combination with IgG1 anti-tumor monoclonal antibodies.

The need for immune biomarkers for treatment prognosis and response in genitourinary malignancies

Immune biomarkers encompass a wide range of blood-borne and cell-associated molecules whose detection or expression may change in response to an immune therapy. These immune therapies encompass a range of platforms including autologous cellular products, in other words, dendritic cells, prime boost DNA vaccines, chimeric antigen receptor (CAR) T cells and checkpoint inhibitors. The response to checkpoint inhibitors by a particular cancer may not be necessarily associated with a change in a particular immune biomarker; other immune biomarkers are needed to assess their association with treatment response or a change in the biology that can impact on the immunologic milieu. How these potential biomarkers can be incorporated into clinical trial design, and their role in interrogating the immunologic milieu will be discussed.

Discovery and application of immune biomarkers for hematological malignancies

INTRODUCTION

Hematological malignancies originate and progress in primary and secondary lymphoid organs, where they establish a uniquely immune-suppressive tumour microenvironment. Although high-throughput transcriptomic and proteomic approaches are being employed to interrogate immune surveillance and escape mechanisms in patients with solid tumours, and to identify actionable targets for immunotherapy, our knowledge of the immunological landscape of hematological malignancies, as well as our understanding of the molecular circuits that underpin the establishment of immune tolerance, is not comprehensive. Areas covered: This article will discuss how multiplexed immunohistochemistry, flow cytometry/mass cytometry, proteomic and genomic techniques can be used to dynamically capture the complexity of tumour-immune interactions. Moreover, the analysis of multi-dimensional, clinically annotated data sets obtained from public repositories such as Array Express, TCGA and GEO is crucial to identify immune biomarkers, to inform the rational design of immune therapies and to predict clinical benefit in individual patients. We will also highlight how artificial neural network models and alternative methodologies integrating other algorithms can support the identification of key molecular drivers of immune dysfunction. Expert commentary: High-dimensional technologies have the potential to enhance our understanding of immune-cancer interactions and will support clinical decision making and the prediction of therapeutic benefit from immune-based interventions.

Pretreatment antigen-specific immunity and regulation - association with subsequent immune response to anti-tumor DNA vaccination

BACKGROUND

Immunotherapies have demonstrated clinical benefit for many types of cancers, however many patients do not respond, and treatment-related adverse effects can be severe. Hence many efforts are underway to identify treatment predictive biomarkers. We have reported the results of two phase I trials using a DNA vaccine encoding prostatic acid phosphatase (PAP) in patients with biochemically recurrent prostate cancer. In both trials, persistent PAP-specific Th1 immunity developed in some patients, and this was associated with favorable changes in serum PSA kinetics. In the current study, we sought to determine if measures of antigen-specific or antigen non-specific immunity were present prior to treatment, and associated with subsequent immune response, to identify possible predictive immune biomarkers.

METHODS

Patients who developed persistent PAP-specific, IFNγ-secreting immune responses were defined as immune "responders." The frequency of peripheral T cell and B cell lymphocytes, natural killer cells, monocytes, dendritic cells, myeloid derived suppressor cells, and regulatory T cells were assessed by flow cytometry and clinical laboratory values. PAP-specific immune responses were evaluated by cytokine secretion in vitro, and by antigen-specific suppression of delayed-type hypersensitivity to a recall antigen in an in vivo SCID mouse model.

RESULTS

The frequency of peripheral blood cell types did not differ between the immune responder and non-responder groups. Non-responder patients tended to have higher PAP-specific IL-10 production pre-vaccination (p = 0.09). Responder patients had greater preexisting PAP-specific bystander regulatory responses that suppressed DTH to a recall antigen (p = 0.016).

CONCLUSIONS

While our study population was small (n = 38), these results suggest that different measures of antigen-specific tolerance or regulation might help predict immunological outcome from DNA vaccination. These will be prospectively evaluated in an ongoing randomized, phase II trial.

Identifying baseline immune-related biomarkers to predict clinical outcome of immunotherapy

As cancer strikes, individuals vary not only in terms of factors that contribute to its occurrence and development, but as importantly, in their capacity to respond to treatment. While exciting new therapeutic options that mobilize the immune system against cancer have led to breakthroughs for a variety of malignancies, success is limited to a subset of patients. Pre-existing immunological features of both the host and the tumor may contribute to how patients will eventually fare with immunotherapy. A broad understanding of baseline immunity, both in the periphery and in the tumor microenvironment, is needed in order to fully realize the potential of cancer immunotherapy. Such interrogation of the tumor, blood, and host immune parameters prior to treatment is expected to identify biomarkers predictive of clinical outcome as well as to elucidate why some patients fail to respond to immunotherapy. To approach these opportunities for progress, the Society for Immunotherapy of Cancer (SITC) reconvened the Immune Biomarkers Task Force. Comprised of an international multidisciplinary panel of experts, Working Group 4 sought to make recommendations that focus on the complexity of the tumor microenvironment, with its diversity of immune genes, proteins, cells, and pathways naturally present at baseline and in circulation, and novel tools to aid in such broad analyses.

Analyses of the peripheral immunome following multiple administrations of avelumab, a human IgG1 anti-PD-L1 monoclonal antibody

Background

Multiple anti-PD-L1/PD-1 checkpoint monoclonal antibodies (MAb) have shown clear evidence of clinical benefit. All except one have been designed or engineered to omit the possibility to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) as a second potential mode of anti-tumor activity; the reason for this is the concern of lysis of PD-L1 positive immune cells. Avelumab is a fully human IgG1 MAb which has been shown in prior in vitro studies to mediate ADCC versus a range of human tumor cells, and clinical studies have demonstrated anti-tumor activity versus a range of human cancers. This study was designed to investigate the effect on immune cell subsets in the peripheral blood of cancer patients prior to and following multiple administrations of avelumab.

Methods

One hundred twenty-three distinct immune cell subsets in the peripheral blood of cancer patients (n = 28) in a phase I trial were analyzed by flow cytometry prior to and following one, three, and nine cycles of avelumab. Changes in soluble (s) CD27 and sCD40L in plasma were also evaluated. In vitro studies were also performed to determine if avelumab would mediate ADCC of PBMC.

Results

No statistically significant changes in any of the 123 immune cell subsets analyzed were observed at any dose level, or number of doses, of avelumab. Increases in the ratio of sCD27:sCD40L were observed, suggesting potential immune activation. Controlled in vitro studies also showed lysis of tumor cells by avelumab versus no lysis of PBMC from five donors.

Conclusions

These studies demonstrate the lack of any significant effect on multiple immune cell subsets, even those expressing PD-L1, following multiple cycles of avelumab. These results complement prior studies showing anti-tumor effects of avelumab and comparable levels of adverse events with avelumab versus other anti-PD-1/PD-L1 MAbs. These studies provide the rationale to further exploit the potential ADCC mechanism of action of avelumab as well as other human IgG1 checkpoint inhibitors.

Trial registration

ClinicalTrials.gov identifier: NCT01772004 (first received: 1/14/13; start date: January 2013) and NCT00001846 (first received date: 11/3/99; start date: August 1999).

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0220-y) contains supplementary material, which is available to authorized users.

Meeting Report From the Prostate Cancer Foundation Scientific Working Group on Radium-223

INTRODUCTION

The Prostate Cancer Foundation (PCF) convened a Scientific Working Group Meeting on Radium-223 on September 8, 2016, at The Sidney Kimmel Center for Prostate and Urologic Cancers, Memorial Sloan Kettering Cancer Center.

METHODS

The meeting was attended by 18 investigators with expertise in radium-223, bone biology, molecular imaging, biomarkers, and prostate cancer clinical trials. The goal of this meeting was to discuss the known and unknown surroundings the therapeutic effects of the bone targeting agent radium-223, in bone metastatic prostate cancer therapy, and to outline the most critical studies needed to improve the clinical use of this agent.

RESULTS

Three major topic areas were discussed: (1) the basic science of radium; (2) immuno-adjuvant properties of radium therapy; and (3) high impact clinical trials and correlative science.

DISCUSSION

This article reviews the major topics discussed at the meeting for the purpose of accelerating studies that will improve the use of radium-223 in the treatment of prostate cancer patients. Prostate 77:245-254, 2017. © 2016 Wiley Periodicals, Inc.