The VE-PTP Inhibitor AKB-9778 Improves Antitumor Activity and Diminishes the Toxicity of Interleukin 2 (IL-2) Administration Administration of interleukin (IL)-2 has led to a durable response in patients with advanced renal cancer and melanoma but is restricted for clinical application because of adverse effects, including the vascular leak syndrome (VLS). VLS is associated with increased circulating levels of the Tie2 antagonist ligand, angiopoietin 2, and decreased Tie2 receptor phosphorylation and downstream signaling in endothelial cells (ECs). Given that vascular endothelial protein tyrosine phosphatase (VE-PTP) is a specific membrane phosphatase in ECs that dephosphorylates Tie2, the effects of targeting VE-PTP by a selective inhibitor AKB-9778 (AKB) in terms of VLS and antitumor efficacy were examined in this study. The authors found, by targeting VE-PTP, that the antitumor effects induced by IL-2 were augmented [tumor-free 44% (IL-2 alone) vs. 87.5% (IL-2+AKB)], associated with enhanced immune cell infiltrate (90% increase for CD8 T cells and natural killer cells). In addition, the side effects of IL-2 therapy were lessened, as demonstrated by diminished lung weight (less vascular leakage) as well as reduced cytokine levels (serum HMGB1 from 137.04±2.69 to 43.86±3.65 pg/mL; interferon-γ from 590.52±90.52 to 31.37±1.14 pg/mL). The authors further sought to determine the potential mechanism of the action of AKB-9778. The findings suggest that AKB-9778 may function through reducing serum angiopoietin 2 level and regulating EC viability. These findings provide insights into the targeting VE-PTP to improve tolerance and efficacy of IL-2 therapy and highlight the clinical potential of AKB-9778 for treating patients with VLS and cancer.

Identification of a Promiscuous Epitope Peptide Derived From HSP70 We previously found that heat-shock protein 70 (HSP70) is expressed on hepatocellular carcinoma cells and developed an HSP70 mRNA-transfected dendritic cell therapy for treating unresectable or recurrent hepatocellular carcinoma. The phase I trial was completed successfully. The purpose of this study is to identify a promiscuous epitope peptide derived from HSP70 for the purpose of developing a novel cancer peptide vaccine. Using a computational algorithm to analyze the specificity of previously reported major histocompatibility complex class I–binding peptides, we selected candidates that bound to >2 of the 3 HLA types. Twenty-nine HSP70-derived peptides (9-mers) that bound to HLA-class I was selected. The peptides were prioritized based on the results of peptide binding experiments. Using dendritic cells stimulated with the candidate peptide described previously as stimulators and CD8+ T cells as effectors, an ELISPOT assay was performed. Cytotoxicity of CD8 lymphocytes stimulated with the candidate peptides toward HSP70-expressing cancer cells was analyzed using an xCELLigence System. Peptides were administered to HLA-A 24 transgenic mice as vaccines, and peptide-specific T-cell induction was measured in vivo. We identified a multi-HLA-class I–binding epitope peptide that bound to HLA-A*02:01, *02:06, and *24:02 in vitro using an interferon-γ ELISPOT immune response induction assay. Cytotoxicity was confirmed in vitro, and safety and immune response induction were confirmed in vivo using HLA-A 24 transgenic mice. Our study demonstrated that the promiscuous HSP70-derived peptide is applicable to cancer immunotherapy in patients with HLA-A*24:02-positive, *02:01-positive, and *02:06-positive HSP70-expressing cancers.

Prognostic Significance of Hematological Indices in Malignant Melanoma Treated With Immune Checkpoint Inhibitors Local and systemic inflammation significantly effects tumor progression and its response to therapy. We aim to evaluate the prognostic significance of inflammatory cells, their ratios, and a change in these indices while patients are receiving immune checkpoint inhibitors (ICIs). We retrospectively reviewed 120 malignant melanoma patients who had received any ICIs from 2011 until December 2017 and evaluated the effect of hematological indices on survival and radiographic responses. We followed the trends of these indices at 0, 6, and 12 weeks while on ICIs. Univariate and multivariate survival analyses were performed. The Student t tests and logistic regression were performed as well. Patients with neutrophil to lymphocyte ratio (NLR) <5 and derived neutrophil to lymphocyte ratio (dNLR) <3 had better overall survival and progression-free survival. The objective response rate was significantly higher in patients with absolute neutrophil count (ANC) <5 and dNLR<3 at baseline. Responder to ICIs had downtrending median ANC, NLR, dNLR, and an uptrending median lymphocyte to monocyte ratio compared with those of nonresponders. Moreover, in responders, the decrease in mean ANC, NLR, and dNLR were statistically significant compared with that of nonresponders at 6 and 12 weeks while on ICIs. Hematological indices can predict the response to ICIs and prognosis in malignant melanoma. Besides, the changes in these indices from their baseline values could be monitored in real-time to predict an earlier response even before a radiographic evaluation. However, the prospective and validation studies are needed before these models can be used in routine clinical practices.

A Brief Communication on Circulating PD-1-positive T-Regulatory Lymphocytes in Melanoma Patients Undergoing Adjuvant Immunotherapy With Nivolumab Upregulation of T-regulatory lymphocytes (Tregs) is one of numerous immune escape mechanisms of malignancies. In the present pilot study we aimed to study the effect of adjuvant nivolumab during the initiation of treatment on circulating Tregs subpopulations in patients with stage III melanoma. We subsequently recruited patients with stage III melanoma who had the indication for adjuvant anti-programmed death 1 (PD-1) treatment with nivolumab. Blood collections were performed before the initiation of nivolumab and before every 2-week therapy cycle. Flow cytometry was performed for the determination of circulating CD4+CD25highCD127−PD-1+(PD-1+Tregs) and CD4+CD25highCD127−CTLA-4+ (CTLA-4+Tregs) Treg populations. Circulating PD-1+Tregs [18.1% (range, 2.9%–41.7%) vs. 4.2% (0.4%–9.8%), P=0.0001] significantly decreased after the first cycle of immunotherapy and maintained decreased during a 3-month course of treatment. By contrast, CTLA-4+Tregs significantly increased after the first nivolumab dose when compared with CTLA-4+Tregs before the second treatment [0.75 (0–45.5) vs. 2.1 (0.1–90.8), P=0.0002]. Blood levels of PD-1+Tregs and CTLA-4+Tregs remained more or less decreased and increased during a 3-month therapy with nivolumab, respectively. Data of PD-1+Tregs as well as CTLA-4+Tregs was not significantly associated with frequencies of immune-related adverse events (P<0.05). In conclusion, we have demonstrated that circulating PD-1+Tregs of melanoma patients in stage III rapidly and continuously decline after the initiation of adjuvant treatment with the PD-1 blocking antibody nivolumab. By contrast, this decline is paralleled with an increase of CTLA-4+Tregs. The expression of PD-1 and CTLA-4 on Tregs might be a potential biomarker for the efficacy of immune checkpoint blockade in melanoma.

PD-L1 Expression in De Novo Metastatic Castration-sensitive Prostate Cancer De novo metastatic castration-sensitive prostate cancer (mCSPC) is small subgroup of prostate cancer associated with poor prognosis. The aim of our study was to assess the expression of programmed death-ligand 1 (PD-L1) in tumor cells of de novo mCSPC patients. Patients referred to our institution from January 2007 to October 2017 with de novo mCSPC and available diagnostic tissue were included. We tested the PD-L1 pharmaDx qualitative immunohistochemical assay, a monoclonal rabbit anti-PD-L1, clone 28-8 intended for use in the detection of PD-L1 protein in formalin-fixed paraffin-embedded. Kaplan-Meier method was used to estimate survivals according to the expression of PD-L1. The study population included 32 de novo mCSPC patients, analyzed for PD-L1 expression using 2 cut-off values (1% and 5%) to define the positivity. Total of 46.9% of cases had tumor PD-L1 expression ≥1%, and 31.3% had expression ≥5%. No differences were found between the PD-L1 expression ≥1% and the involvement of liver, lung, and number of bone metastases, and the disease volume based on CHAARTED classification. PD-L1− tumors had higher incidence of Gleason score ≥8 compared with PD-L1+ tumors (P=0.037), while the incidence of lymph node metastases was higher in PD-L1+ tumors (P=0.044). No difference in the median overall survival (mOS) was observed between the PD-L1− population and the PD-L1+ patients (43.8 vs. 29.6 mo; P=0.88). The tumor PD-L1 expression cannot be considered a prognostic factor for de novo mCSPC, even if its prognostic and predictive significance have to be thoroughly investigated to better define the selected group of prostate cancer patients that might benefit from checkpoint blockade immunotherapy.

Metastatic Mixed Adenoneuroendocrine Carcinoma of the Colon with Response to Immunotherapy with Pembrolizumab: A Case Report Mixed adenoneuroendocrine carcinoma (MANEC) is a rare, aggressive tumor arising from different localizations along the gastrointestinal tract with generally poor prognosis. We present the case of a 51-year-old female patient with histopathologically confirmed diagnosis of a MANEC of the descending colon. At presentation, the tumor had already spread to the liver causing extensive hepatic metastases. Immunohistochemical examination showed 5%–10% of tumor cells to express the programmed cell death receptor ligand 1 and FoundationOne testing revealed a high mutational tumor burden with 149 Muts/Mb. The patient responded very well clinically and radiologically to anti-programmed death 1 receptor monoclonal antibody pembrolizumab therapy after having undergone 3 previous systemic treatment regimens as well as selective internal radiation therapy of her hepatic metastases. Clinical improvement was evident after the first infusion already and is ongoing for 10 months so far with very little side effects including initial and short lived skin irritation as well as muscle pain. To our knowledge, this is the first published case where a MANEC was successfully treated with immunotherapy targeting the programmed death 1 receptor.