Novel biological strategies to enhance the radiation therapeutic ratio

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Metformin and Breast Cancer: Where Are We Now?

Breast cancer is the most prevalent cancer and the leading cause of cancer-related death among women worldwide. Type 2 diabetes–associated metabolic traits such as hyperglycemia, hyperinsulinemia, inflammation, oxidative stress, and obesity are well-known risk factors for breast cancer. The insulin sensitizer metformin, one of the most prescribed oral antidiabetic drugs, has been suggested to function as an antitumoral agent, based on epidemiological and retrospective clinical data as well as preclinical studies showing an antiproliferative effect in cultured breast cancer cells and animal models. These benefits provided a strong rationale to study the effects of metformin in routine clinical care of breast cancer patients. However, the initial enthusiasm was tempered after disappointing results in randomized controlled trials, particularly in the metastatic setting. Here, we revisit the current state of the art of metformin mechanisms of action, critically review past and current metformin-based clinical trials, and briefly discuss future perspectives on how to incorporate metformin into the oncologist’s armamentarium for the prevention and treatment of breast cancer.

MnTnHex-2-PyP5+, Coupled to Radiation, Suppresses Metastasis of 4T1 and MDA-MB-231 Breast Cancer via AKT/Snail/EMT Pathways

Tumor migration and invasion induced by the epithelial-to-mesenchymal transition (EMT) are prerequisites for metastasis. Here, we investigated the inhibitory effect of a mimic of superoxide dismutase (SOD), cationic Mn(III) ortho-substituted N-n-hexylpyridylporphyrin (MnTnHex-2-PyP⁵⁺, MnHex) on the metastasis of breast cancer in cellular and animal models, focusing on the migration of tumor cells and the factors that modulate this behavior. Wound healing and Transwell migration assays revealed that the migration of mouse mammary carcinoma 4T1 cells was markedly reduced during the concurrent treatment of MnHex and radiation therapy (RT) compared with that of the control and RT alone. Bioluminescence imaging showed that MnHex/RT co-treatment dramatically reduced lung metastasis of 4T1 cells in mice, compared with the sham control and both single treatments. Western blotting and immunofluorescence showed that MnHex treatment of 4T1 cells reversed the RT-induced EMT via inhibiting AKT/GSK-3β/Snail pathway in vitro, thereby decreasing cell migration and invasion. Consistently, histopathological analyses of 4T1 tumors showed that MnHex/RT reduced Snail expression, blocked EMT, and in turn suppressed metastases. Again, in the human metastatic breast cancer MDA-MB-231 cell line, MnHex inhibited metastatic potential in vitro and in vivo and suppressed the RT-induced Snail expression. In addition to our previous studies showing tumor growth inhibition, this study demonstrated that MnHex carries the ability to minimize the metastatic potential of RT-treated cancers, thus overcoming their radioresistance.

Clinical Significance of Systemic Inflammation Markers in Newly Diagnosed, Previously Untreated Hepatocellular Carcinoma

This study aimed to investigate the clinical significance of systemic inflammation markers (SIMs)-including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR)-in patients with newly diagnosed, previously untreated hepatocellular carcinoma (HCC). The present study was performed using prospectively collected registry data of newly diagnosed, previously untreated HCC from a single institution. The training set included 6619 patients from 2005 to 2013 and the validation set included 2084 patients from 2014 to 2016. The SIMs as continuous variables significantly affected the overall survival (OS), and the optimal cut-off value of NLR, PLR, and LMR was 3.0, 100.0, and 3.0, respectively. There were significant correlations between SIMs and the albumin-bilirubin grade/Child-Turcotte-Pugh class (indicative of liver function status) and the staging system/portal vein invasion (indicative of the tumor burden). The OS curves were well stratified according to the prognostic model of SIMs and validated using the bootstrap method (1000 times, C-index 0.6367, 95% confidence interval (CI) 0.6274-0.6459) and validation cohort (C-index 0.6810, 95% CI 0.6570-0.7049). SIMs showed significant prognostic ability for OS, independent of liver function and tumor extent, although these factors were significantly correlated with SIMs in patients with newly diagnosed, previously untreated HCC.

Outcomes of Radiotherapy for Mesenchymal and Non-Mesenchymal Subtypes of Gastric Cancer

Background: The purpose of this study was to evaluate the clinical outcomes following postoperative chemotherapy (XP) versus chemoradiotherapy (XP-RT) according to mesenchymal subtype based on RNA sequencing in gastric cancer (GC) in a cohort of the Adjuvant chemoRadioTherapy In Stomach Tumor (ARTIST) trial. Methods: Of the 458 patients enrolled in the ARTIST trial, formalin-fixed, paraffin-embedded (FFPE) specimens were available from 106 (23.1%) patients for RNA analysis. The mesenchymal subtype was classified according to a previously reported 71-gene MSS/EMT signature using the NanoString assay. Results: Of the 106 patients analyzed (50 in XP arm, 56 in XP-RT arm), 36 (34.0%) patients were categorized as mesenchymal subtype by NanoString assay. Recurrence-free survival (RFS, p = 0.009, hazard ratio (HR) = 2.11, 95% confidence interval (CI): 1.21-3.70) and overall survival (OS, p = 0.003, HR = 2.28, 95% CI: 1.31-3.96) were significantly lower in the mesenchymal subtype than in the non-mesenchymal subtype. In terms of post-operative radiotherapy (RT), mesenchymal subtype was not an independent variable to predict RFS or OS regardless to the assigned arm (XP with or without RT) in this patient cohort. However, there was a trend in the adjuvant XP arm, which showed higher OS than the XP-RT arm for the mesenchymal subtype and lower OS than the XP-RT arm for the non-mesenchymal subtype. Conclusions: We could not determine any significant differences between the mesenchymal and non-mesenchymal subtypes with respect to the effects of adjuvant XP with or without RT in gastric cancer following curative surgery.

Clinical significance of radiotherapy before and/or during nivolumab treatment in hepatocellular carcinoma

Background

This study aimed to investigate the clinical significance of previous and/or concurrent application of radiotherapy (RT) in the course of nivolumab treatment for advanced hepatocellular carcinoma (HCC).

Methods

Patients with advanced HCC who received nivolumab treatment between March 2017 and May 2018. were included. Nivolumab treatment was indicated in patients who did not respond to conventional therapy including locoregional therapy and/or sorafenib. RT was performed when necessary for curative/palliative purpose.

Results

Among the 76 HCC patients who received nivolumab, 54 (71.1%) had received RT for HCC before and/or during the treatment. The period from initial HCC diagnosis to nivolumab treatment was significantly longer (P = .007) and the rate of undergoing transarterial chemoembolization (TACE; P = .006) and sorafenib treatment (P = .007) was significantly higher in patients who received previous/concurrent RT than in those who did not. Nivolumab‐related toxicities were generally tolerable regardless of the history of RT. During the follow‐up, 39 (51.3%) patients died and 54 (71.1%) patients experienced disease progression according to the RECIST v1.1. Patients who had received previous/concurrent RT had a significantly longer progression‐free survival (PFS; P = .008) and overall survival (OS; P = .007) than those who did not receive RT; however, this trend was not observed in patients with a history of radiofrequency ablation or TACE (all P > .05).

Conclusion

Previous and/or concurrent application of RT in the course of nivolumab treatment was related with longer PFS and OS in advanced HCC patients. Nonetheless, further clinical studies are warranted to confirm our findings.

Identification of FES as a Novel Radiosensitizing Target in Human Cancers

PURPOSE

The identification of novel targets for developing synergistic drug-radiation combinations would pave the way to overcome tumor radioresistance. We conducted cell-based screening of a human kinome siRNA library to identify a radiation-specific kinase that has a synergistic toxic effect with radiation upon inhibition and is not essential for cell survival in the absence of radiation.

EXPERIMENTAL DESIGN

Unbiased RNAi screening was performed by transfecting A549 cells with a human kinome siRNA library followed by irradiation. Radiosensitizing effects of a target gene and involved mechanisms were examined.

RESULTS

We identified the nonreceptor protein tyrosine kinase FES (FEline Sarcoma oncogene) as a radiosensitizing target. The expression of FES was increased in response to irradiation. Cell viability and clonogenic survival after irradiation were significantly decreased by FES knockdown in lung and pancreatic cancer cell lines. In contrast, FES depletion alone did not significantly affect cell proliferation without irradiation. An inducible RNAi mouse xenograft model verified in vivo radiosensitizing effects. FES-depleted cells showed increased apoptosis, DNA damage, G₂-M phase arrest, and mitotic catastrophe after irradiation. FES depletion promoted radiation-induced reactive oxygen species formation, which resulted in phosphorylation of S6K and MDM2. The radiosensitizing effect of FES knockdown was partially reversed by inhibition of S6K activity. Consistent with the increase in phosphorylated MDM2, an increase in nuclear p53 levels was observed, which appears to contribute increased radiosensitivity of FES-depleted cells.

CONCLUSIONS

We uncovered that inhibition of FES could be a potential strategy for inducing radiosensitization in cancer. Our results provide the basis for developing novel radiosensitizers.

Targeted Therapies and Immune-Checkpoint Inhibition in Head and Neck Squamous Cell Carcinoma: Where Do We Stand Today and Where to Go?

With an increased understanding of the tumor biology of squamous cell carcinoma of the head and neck (SCCHN), targeted therapies have found their way into the clinical treatment routines against this entity. Nevertheless, to date platinum-based cytostatic agents remain the first line choice and targeting the epidermal growth factor-receptor (EGFR) with combined cetuximab and radiation therapy remains the only targeted therapy approved in the curative setting. Investigation of immune checkpoint inhibitors (ICI), such as antibodies targeting programmed cell death protein 1 (PD-1) and its ligand PD-L1, resulted in a change of paradigms in oncology and in the first approval of new drugs for treating SCCHN. Nivolumab and pembrolizumab, two anti-PD-1 antibodies, were the first agents shown to improve overall survival for patients with metastatic/recurrent tumors in recent years. Currently, several clinical trials investigate the role of ICI in different therapeutic settings. A robust set of biomarkers will be an inevitable tool for future individualized treatment approaches including radiation dose de-escalation and escalation strategies. This review aims to summarize achieved goals, the current status and future perspectives regarding targeted therapies and ICI in the management of SCCHN.