Hypofractionated Irradiation Suppressed the Off-Target Mouse Hepatocarcinoma Growth by Inhibiting Myeloid-Derived Suppressor Cell-Mediated Immune Suppression

Radiation and Immune Checkpoint Inhibitors: Combination Therapy for Treatment of Hepatocellular Carcinoma

The liver tumor immune microenvironment has been thought to possess a critical role in the development and progression of hepatocellular carcinoma (HCC). Despite the approval of immune checkpoint inhibitors (ICIs), such as programmed cell death receptor 1 (PD-1)/programmed cell death ligand 1 (PD-L1) and cytotoxic T lymphocyte associated protein 4 (CTLA-4) inhibitors, for several types of cancers, including HCC, liver metastases have shown evidence of resistance or poor response to immunotherapies. Radiation therapy (RT) has displayed evidence of immunosuppressive effects through the upregulation of immune checkpoint molecules post-treatment. However, it was revealed that the limitations of ICIs can be overcome through the use of RT, as it can reshape the liver immune microenvironment. Moreover, ICIs are able to overcome the RT-induced inhibitory signals, effectively restoring anti-tumor activity. Owing to the synergetic effect believed to arise from the combination of ICIs with RT, several clinical trials are currently ongoing to assess the efficacy and safety of this treatment for patients with HCC.

Advances in radiotherapy and immunity in hepatocellular carcinoma

Primary liver cancer is one of the most common malignant tumours worldwide; it caused approximately 830,000 deaths in 2020. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, accounting for over 80% of all cases. Various methods, including surgery, chemotherapy, radiotherapy, and radiofrequency ablation, have been widely used in the treatment of HCC. With the advancement of technology, radiotherapy has become increasingly important in the comprehensive treatment of HCC. However, due to the insufficient sensitivity of tumour cells to radiation, there are still multiple limitation in clinical application of radiotherapy. In recent years, the role of immunotherapy in cancer has been increasingly revealed, and more researchers have turned their attention to the combined application of immunotherapy and radiotherapy in the hope of achieving better treatment outcomes. This article reviews the progress on radiation therapy in HCC and the current status of its combined application with immunotherapy, and discusses the prospects and value of radioimmunotherapy in HCC.

Strategies to Optimize Treatment for Locally Advanced Rectal Cancer

Neoadjuvant long-course concurrent chemoradiation plus surgery, followed by optional adjuvant chemotherapy, is a standard of care for locally advanced rectal cancer (LARC). However, this traditional approach has several limitations, including low pathological complete response (pCR) (10-25%), high metastasis rate (30-35%), and highly inconsistent compliance with adjuvant chemotherapy (25-75%). Treatment modalities for LARC have dramatically evolved in recent years. Multiple clinical trials have focused on optimizing strategies to achieve a win-win situation for oncologic outcomes and functions. Here, we review the latest studies into optimizing neoadjuvant treatment for LARC.

Myeloid-Derived Suppressor Cells and Radiotherapy

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of pathologically activated, mostly immature, myeloid cells that exert robust immunosuppressive functions. MDSCs expand during oncogenesis and have been linked to accelerated disease progression and resistance to treatment in both preclinical tumor models and patients with cancer. Thus, MDSCs stand out as promising targets for the development of novel immunotherapeutic regimens with superior efficacy. Here, we summarize accumulating preclinical and clinical evidence indicating that MDSCs also hamper the efficacy of radiotherapy (RT), as we critically discuss the potential of MDSC-targeting strategies as tools to achieve superior immunotherapeutic tumor control by RT in the clinic.

Neutrophils as potential therapeutic targets in hepatocellular carcinoma

The success of atezolizumab plus bevacizumab treatment contributed to a shift in systemic therapies for hepatocellular carcinoma (HCC) towards combinations that include cancer immunotherapeutic agents. Thus far, the principal focus of cancer immunotherapy has been on interrupting immune checkpoints that suppress antitumour lymphocytes. As well as lymphocytes, the HCC environment includes numerous other immune cell types, among which neutrophils are emerging as an important contributor to the pathogenesis of HCC. A growing body of evidence supports neutrophils as key mediators of the immunosuppressive environment in which some cancers develop, as well as drivers of tumour progression. If neutrophils have a similar role in HCC, approaches that target or manipulate neutrophils might have therapeutic benefits, potentially including sensitization of tumours to conventional immunotherapy. Several neutrophil-directed therapies for patients with HCC (and other cancers) are now entering clinical trials. This Review outlines the evidence in support of neutrophils as drivers of HCC and details their mechanistic roles in development, progression and metastasis, highlighting the reasons that neutrophils are well worth investigating despite the challenges associated with studying them. Neutrophil-modulating anticancer therapies entering clinical trials are also summarized.

Epidemiological and anatomopathological profile of breast cancer in the region of North-West of Tunisia

INTRODUCTION

Breast cancer is a common and serious disease. It represents the first cause of mortality and morbidity from cancer of Tunisian women and worldwide.

AIM

To analyze the clinico-pathological and evolutionary characteristics of the patients followed at the carcinology's pole in the region of the North-West of Tunisia.

METHODS

We conducted a retrospective descriptive study of 114 patients, who were diagnosed with non metastatic breast cancers over a 6-year period, from January 2011 to December 2016.

RESULTS

Among the 289 patients treated in the medical carcinology department of the Jendouba regional hospital for invasive breast carcinoma over a period of 6 years, 114 patients had localized breast carcinoma, they were the subject of our study. The average age was 51 years. Nonspecific invasive cancer was the most frequent histological type (95.6%). The mean histological size was 29.3 mm. SBR grade II was most prevalent. Histological lymph node involvement was observed in 50.9%. Lymphovascular invasion was detected in 23.9% of cases and perineural sheaths was detected in 21.9% of cases. The most common molecular subtype was Luminal B. After discussion in a multidisciplinary concertation meeting, the patients received locoregional treatment: surgery, radiotherapy and systemic treatment: chemotherapy, endocrine hormone therapy. After a median follow-up of 45 months, OS and PFS at 5 years were 85.6% and 79.2% respectively.

CONCLUSION

In the region of the North-West of Tunisia, breast cancer is characterized by its occurrence at a young age, the importance of tumor size, the importance of lymph node involvement, the frequency of inflammatory breast carcinoma and especially by the predominance of the molecular groups Luminal B and HER2 neu.

Immunomodulatory effects of G-CSF in cancer: Therapeutic implications

Numerous preclinical studies have reported a pro-tumour role for granulocyte colony-stimulating factor (G-CSF) that is predominantly mediated by neutrophils and MDSCs, the major G-CSF receptor expressing populations. In the presence of G-CSF (either tumour-derived or exogenous) these myeloid populations commonly exhibit a T cell suppressive phenotype. However, the direct effects of this cytokine on other immune lineages, such as T and NK cells, are not as well established. Herein we discuss the most recent data relating to the effect of G-CSF on the major immune populations, exclusively in the context of cancer. Recent publications have drawn attention to the other tumour-promoting effects of G-CSF on myeloid cells, including NETosis, promotion of cancer stemness and skewed differentiation of bone marrow progenitors towards myelopoiesis. Although G-CSF is safely and commonly used as a supportive therapy to prevent or treat chemotherapy-associated neutropenia in cancer patients, we also discuss the potential impacts of G-CSF on other anti-cancer treatments. Importantly, considerations for immune checkpoint blockade are highlighted, as many publications report a T cell suppressive effect of G-CSF that may diminish the effectiveness of this immunotherapy.

Lattice or Oxygen-Guided Radiotherapy: What If They Converge? Possible Future Directions in the Era of Immunotherapy

Palliative radiotherapy has a great role in the treatment of large tumor masses. However, treating a bulky disease could be difficult, especially in critical anatomical areas. In daily clinical practice, short course hypofractionated radiotherapy is delivered in order to control the symptomatic disease. Radiation fields generally encompass the entire tumor mass, which is homogeneously irradiated. Recent technological advances enable delivering a higher radiation dose in small areas within a large mass. This goal, previously achieved thanks to the GRID approach, is now achievable using the newest concept of LATTICE radiotherapy (LT-RT). This kind of treatment allows exploiting various radiation effects, such as bystander and abscopal effects. These events may be enhanced by the concomitant use of immunotherapy, with the latter being ever more successfully delivered in cancer patients. Moreover, a critical issue in the treatment of large masses is the inhomogeneous intratumoral distribution of well-oxygenated and hypo-oxygenated areas. It is well known that hypoxic areas are more resistant to the killing effect of radiation, hence the need to target them with higher aggressive doses. This concept introduces the "oxygen-guided radiation therapy" (OGRT), which means looking for suitable hypoxic markers to implement in PET/CT and Magnetic Resonance Imaging. Future treatment strategies are likely to involve combinations of LT-RT, OGRT, and immunotherapy. In this paper, we review the radiobiological rationale behind a potential benefit of LT-RT and OGRT, and we summarize the results reported in the few clinical trials published so far regarding these issues. Lastly, we suggest what future perspectives may emerge by combining immunotherapy with LT-RT/OGRT.

Radiation-induced abscopal effect and its enhancement by programmed cell death 1 blockade in the hepatocellular carcinoma: A murine model study

BACKGROUND/AIMS

The abscopal effect, a rare phenomenon induced by radiation, can be reinforced by immunotherapy. Although radiation therapy and immunotherapy are increasingly being utilized for the treatment of hepatocellular carcinoma (HCC), whether immunotherapy could boost the abscopal effect remains unclear. In this study, we aimed to elucidate the immunological mechanisms underlying the abscopal effect induced by the combination of irradiation and immunotherapy in a murine HCC model.

METHODS

A syngeneic HCC mouse model was established by transplanting murine Hepa 1-6 HCC cells into both hind legs of immunocompetent C57BL/6 mice. The tumors on the right hind legs were irradiated, and abscopal effects were observed in the non-irradiated tumors on the left hind leg with or without the coadministration of anti-programmed cell death 1 (PD-1) antibodies. Flow cytometric analyses were performed to analyze the distributions of immune cells infiltrating both irradiated and non-irradiated tumors and the tumor-draining lymph nodes (TDLNs).

RESULTS

Administration of 16 Gy in two fractions more effectively inhibited the growth of both irradiated and nonirradiated tumors with higher tumor infiltration of cytotoxic T cells than 8 Gy did in a single fraction. The higher dose also increased activated dendritic cells in TDLNs, which had higher expression of the programmed cell death ligand 1. Coadministration of anti-PD-1 antibodies significantly enhanced the abscopal effect and increased infiltration of activated cytotoxic T cells in both irradiated and non-irradiated tumors.

CONCLUSION

Our findings show that adding anti-PD-1 therapy to radiation enhanced the abscopal effect in a syngeneic murine model of HCC.

The New Era of Cancer Immunotherapy: Targeting Myeloid-Derived Suppressor Cells to Overcome Immune Evasion

Suppression of antitumor immune responses is one of the main mechanisms by which tumor cells escape from destruction by the immune system. Myeloid-derived suppressor cells (MDSCs) represent the main immunosuppressive cells present in the tumor microenvironment (TME) that sustain cancer progression. MDSCs are a heterogeneous group of immature myeloid cells with a potent activity against T-cell. Studies in mice have demonstrated that MDSCs accumulate in several types of cancer where they promote invasion, angiogenesis, and metastasis formation and inhibit antitumor immunity. In addition, different clinical studies have shown that MDSCs levels in the peripheral blood of cancer patients correlates with tumor burden, stage and with poor prognosis in multiple malignancies. Thus, MDSCs are the major obstacle to many cancer immunotherapies and their targeting may be a beneficial strategy for improvement the efficiency of immunotherapeutic interventions. However, the great heterogeneity of these cells makes their identification in human cancer very challenging. Since both the phenotype and mechanisms of action of MDSCs appear to be tumor-dependent, it is important to accurately characterized the precise MDSC subsets that have clinical relevance in each tumor environment to more efficiently target them. In this review we summarize the phenotype and the suppressive mechanisms of MDSCs populations expanded within different tumor contexts. Further, we discuss about their clinical relevance for cancer diagnosis and therapy.

Deciphering the Intricate Roles of Radiation Therapy and Complement Activation in Cancer

The complement system consists of a collection of serum proteins that act as the main frontline effector arm of the innate immune system. Activation of complement can occur through 3 individual induction pathways: the classical, mannose-binding lectin, and alternative pathways. Activation results in opsonization, recruitment of effector cells through potent immune mediators known as anaphylatoxins, and cell lysis via the formation of the membrane attack complex. Stringent regulation of complement is required to protect against inappropriate activation of the complement cascade. Complement activation within the tumor microenvironment does not increase antitumoral action; instead, it enhances tumor growth and disease progression. Radiation therapy (RT) is a staple in the treatment of malignancies and controls tumor growth through direct DNA damage and the influx of immune cells, reshaping the makeup of the tumor microenvironment. The relationship between RT and complement activity in the tumor microenvironment is uncertain at best. The following review will focus on the complex interaction of complement activation and the immune-modulating effects of RT and the overall effect on tumor progression. The clinical implications of complement activation in cancer and the use of therapeutics and potential biomarkers will also be covered.