Resolution of Gastric Cancer-Promoting Inflammation: A Novel Strategy for Anti-cancer Therapy

The connection between inflammation and cancer was initially recognized by Rudolf Virchow in the nineteenth century. During the last decades, a large body of evidence has provided support to his hypothesis, and now inflammation is recognized as one of the hallmarks of cancer, both in etiopathogenesis and ongoing tumor growth. Infection with the pathogen Helicobacter pylori is the primary causal factor in 90% of gastric cancer (GC) cases. As we increase our understanding of how chronic inflammation develops in the stomach and contributes to carcinogenesis, there is increasing interest in targeting cancer-promoting inflammation as a strategy to treat GC. Moreover, once cancer develops and anti-cancer immune responses are suppressed, there is evidence of a substantial shift in the microenvironment and new targets for immune therapy emerge. In this chapter, we provide insight into inflammation-related factors, including T lymphocytes, macrophages, pro-inflammatory chemokines, and cytokines, which promote H. pylori-associated GC initiation and growth. While intervening with chronic inflammation is not a new practice in rheumatology or gastroenterology, this approach has not been fully explored for its potential to prevent carcinogenesis or to contribute to the treatment of GC. This review highlights current and possible strategies for therapeutic intervention including (i) targeting pro-inflammatory mediators, (ii) targeting growth factors and pathways involved in angiogenesis in the gastric tumor microenvironment, and (iii) enhancing anti-tumor immunity. In addition, we highlight a significant number of clinical trials and discuss the importance of individual tumor characterization toward offering personalized immune-related therapy.

Recent Advances in the Clinical Development of Immune Checkpoint Blockade Therapy for Mismatch Repair Proficient (pMMR)/non-MSI-H Metastatic Colorectal Cancer

Metastatic colorectal cancer (mCRC) continues to be associated with a poor prognosis, and there remains a significant unmet need for novel agents and treatment regimens. Major breakthroughs have been made with immune checkpoint blockade therapy in several disease types, including DNA mismatch repair deficient/microsatellite instability-high (MSI-H) tumors. To date, however, immune checkpoint monotherapy has not shown significant clinical activity in the treatment of patients with mismatch repair proficient (pMMR)/non-MSI-H mCRC. The immune resistance mechanisms in pMMR/non-MSI-H mCRC have not yet been clearly elucidated. Significant efforts are currently focused on identifying effective combination immunotherapy regimens for the treatment of patients with pMMR/non-MSI-H mCRC. The combination of atezolizumab with cobimetinib had shown promising clinical activity in an early-phase clinical trial. Unfortunately, the IMblaze 370 (COTEZO) phase III trial of atezolizumab/cobimetinib combination in patients with mCRC failed to show significant improvement in overall survival in patients treated with the atezolizumab/combimetinib combination in comparison with regorafenib alone. This review summarizes the recent major advances in the clinical development of immunotherapy regimens for patients with pMMR/non-MSI-H mCRC.

Redirected T Cell Cytotoxicity in Cancer Therapy

Bispecific antibodies that recruit and redirect T cells to attack tumor cells have tremendous potential for the treatment of various malignancies. In general, this class of therapeutics, known as CD3 bispecifics, promotes tumor cell killing by cross-linking a CD3 component of the T cell receptor complex with a tumor-associated antigen on the surface of the target cell. Importantly, this mechanism does not rely on a cognate interaction between the T cell receptor and a peptide:HLA complex, thereby circumventing HLA (human leukocyte antigen) restriction. Hence, CD3 bispecifics may find a key role in addressing tumors with low neoantigen content and/or low inflammation, and this class of therapeutics may productively combine with checkpoint blockade. A wide array of formats and optimization approaches has been developed, and a wave of CD3 bispecifics is proceeding into human clinical trials for a range of indications, with promising signs of therapeutic activity.

Targeting Programmed Cell Death -1 (PD-1) and Ligand (PD-L1): A new era in cancer active immunotherapy

Improved understanding of the immune system and its role in cancer development and progression has led to impressive advances in the field of cancer immunotherapy over the last decade. Whilst the field is rapidly evolving and the list of drugs receiving regulatory approval for the treatment of various cancers is fast growing, the group of PD1- PDL-1 inhibitors is establishing a leading role amongst immunomodulatory agents. PD1- PDL-1 inhibitors act against pathways involved in adaptive immune suppression resulting in immune checkpoint blockade. Within the last four years two PD-1 and three PD-L1 inhibitors have been utilized in clinical practice against a variety of malignancies. Focus was initially placed on targeting cancers considered immunogenic such as melanoma, renal and lung cancers but subsequently the application expanded to include amongst others Hodgkin Lymphoma, urothelial as well as head and neck cancer. This article provides a comprehensive review of the early and late phase trials that led to the regulatory approval of all five PD1- PDL-1 inhibitors in the corresponding cancer types. It presents available data on the combinations of PD1- PDL-1 inhibitors with other therapies (immunotherapy, targeted therapy and chemotherapy), the toxicity profile of the PD1- PDL-1 inhibitors and ongoing trials testing the efficacy of these agents in cancer types beyond those that have been addressed already. Finally, current and future challenges in the application of PD-1 and PD-L1 inhibitors are discussed with emphasis on the role of predictive biomarkers.

Drug resistance and new therapies in colorectal cancer

Colorectal cancer (CRC) is often diagnosed at an advanced stage when tumor cell dissemination has taken place. Chemo- and targeted therapies provide only a limited increase of overall survival for these patients. The major reason for clinical outcome finds its origin in therapy resistance. Escape mechanisms to both chemo- and targeted therapy remain the main culprits. Here, we evaluate major resistant mechanisms and elaborate on potential new therapies. Amongst promising therapies is α-amanitin antibody-drug conjugate targeting hemizygous p53 loss. It becomes clear that a dynamic interaction with the tumor microenvironment exists and that this dictates therapeutic outcome. In addition, CRC displays a limited response to checkpoint inhibitors, as only a minority of patients with microsatellite instable high tumors is susceptible. In this review, we highlight new developments with clinical potentials to augment responses to checkpoint inhibitors.

Rationale for Combining Bispecific T Cell Activating Antibodies With Checkpoint Blockade for Cancer Therapy

T cells have been established as core effectors for cancer therapy; this has moved the focus of therapeutic endeavors to effectively enhance or restore T cell tumoricidal activity rather than directly target cancer cells. Both antibodies targeting the checkpoint inhibitory molecules programmed death receptor 1 (PD1), PD-ligand 1 (PD-L1) and cytotoxic lymphocyte activated antigen 4 (CTLA4), as well as bispecific antibodies targeting CD3 and CD19 are now part of the standard of care. In particular, antibodies to checkpoint molecules have gained broad approval in a number of solid tumor indications, such as melanoma or non-small cell lung cancer based on their unparalleled efficacy. In contrast, the efficacy of bispecific antibody-derivatives is much more limited and evidence is emerging that their activity is regulated through diverse checkpoint molecules. In either case, both types of compounds have their limitations and most patients will not benefit from them in the long run. A major aspect under investigation is the lack of baseline antigen-specific T cells in certain patient groups, which is thought to render responses to checkpoint inhibition less likely. On the other hand, bispecific antibodies are also restricted by induced T cell anergy. Based on these considerations, combination of bispecific antibody mediated on-target T cell activation and reversal of anergy bears high promise. Here, we will review current evidence for such combinatorial approaches, as well as ongoing clinical investigations in this area. We will also discuss potential evidence-driven future avenues for testing.

Promising New Agents for Colorectal Cancer

OPINION STATEMENT

Choosing the optimal treatment approach for patients with metastatic colorectal cancer (mCRC) demands that oncologists assess both clinical and genomic variables and individualize care based upon the findings. Clinically, choices depend on assessing the side of the colon in which the primary tumor originates, the sites and burden of metastatic disease, the patient's performance status, and their individual comorbidities. Genomic assessment of the tumor to discern the mutational status of genes such as RAS/RAF, HER2, and TRK, as well as assessing whether tumors have defective mismatch repair (dMMR) or high microsatellite instability (MSI-H), all factor in to potential treatment options and can determine clinical trial eligibility. Metastasectomy may be an option for patients with a low burden of disease and accessible liver- or lung-limited metastases. In some unresectable cases, systemic therapy with a FOLFOX- or FOLFIRI-based regimen with or without a biologic agent can lead to sufficient disease reduction to make a patient eligible for resection of metastatic disease. Tumor sidedness and RAS mutational status guide which biologic we add to the initial chemotherapy backbone, with patients with left-sided, RAS wild-type (WT) tumors receiving anti-epidermal growth factor receptor (EGFR)-directed therapy and patients with right-sided tumors or those with RAS mutations receiving bevacizumab. In patients with tumors that manifest microsatellite instability or deficient mismatch repair, we typically administer checkpoint inhibitors such as pembrolizumab or nivolumab after progression on irinotecan- or oxaliplatin-based therapies. In patients with progressive disease, we routinely send tumor tissue for next generation sequencing (NGS) to assess for the presence of actionable genomic alterations such as HER2, BRAF, and TRK fusions and offer them the option of enrollment on clinical trials with agents targeting those or other identified alterations.

Atezolizumab for the treatment of colorectal cancer: the latest evidence and clinical potential

INTRODUCTION

Atezolizumab is a fully humanized, engineered monoclonal antibody that specifically targets PD-L1, key molecule in the cancer-immunity pathway. Atezolizumab is currently approved for the treatment of metastatic non-small-cell lung cancer and advanced urothelial carcinomas. Areas covered: In this review, we will present the available data supporting the efficacy of atezolizumab for the treatment of metastatic colorectal cancer (mCRC). We will also provide an update on the ongoing/future clinical trials evaluating the role of atezolizumab for the treatment of CRC in different settings (alone or in combination with other checkpoint inhibitors and/or targeted therapies). So far, a small subgroup of mCRC (those with deficiency in mismatch repair - dMMR) appears to benefit significantly from checkpoint inhibitors. As expected, further research is needed to develop biomarkers, effective therapeutic strategies and novel combinations to overcome immune escape resistance and achieve better responses with minimal toxicities. Expert opinion: Interim analyses from ongoing early-phase studies in mCRC have shown encouraging activity of atezolizumab in combination with chemotherapy and/or targeted therapies, especially with MEK inhibitor cobimetinib. Within the next few years, this PD-L1 checkpoint inhibitor will likely be included as one of the treatment options for CRC, at least for patients with dMMR.

Bispecific antibodies for cancer therapy: A review

The ability to produce monoclonal antibodies with defined and distinct specificities has resulted in a vast spectrum of therapeutic monoclonal antibodies including bispecific antibodies (BsAbs). Several types of BsAbs have been produced but the most well-known of these are trispecific antibodies (TrAbs or TrioMabs) and bispecific T cell engager antibodies (BiTE). TrAbs have two variable segments for antigen binding and an Fc component to recruit immune cells. Catumaxomab is a TrAb that has orphan drug status from the Food and Drug Administration (FDA) for EpCam positive gastric and ovarian tumors and was previously approved by the European Medicinal Agency (EMA) for the same indication. One arm of catumaxomab binds to EpCAM, the other binds to CD3 on T cells and the Fc portion recruits immune cells. Catumaxomab is no longer being produced by the manufacturer due to logistic considerations and hence not available in the European market. Blinatumomab is a BiTE that comprises of two variable segments only with one arm binding to CD19 and the other binding to CD3. Blinatumomab has been approved for relapsed or refractory B-cell precursor ALL in adults and children by the FDA. There are over 50 bispecific antibodies currently on clinical trials for various malignancies and the hope is that in the future many of these, with better understanding of principles and techniques of production, will provide treatment options for many different types of cancer.