A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity

Within the innate immune system, effector lymphocytes known as natural killer (NK) cells play an essential role in host defense against aberrant cells, specifically eliminating tumoral and virally infected cells. Approximately 30 known monogenic defects, together with a host of other pathological conditions, cause either functional or classic NK cell deficiency, manifesting in reduced or absent cytotoxic activity. Historically, cytotoxicity has been investigated with radioactive methods, which are cumbersome, expensive and potentially hazardous. This article describes a streamlined, clinically applicable flow cytometry-based method to quantify NK cell cytotoxic activity. In this assay, peripheral blood mononuclear cells (PBMCs) or purified NK cell preparations are co-incubated at different ratios with a target tumor cell line known to be sensitive to NK cell-mediated cytotoxicity (NKCC). The target cells are pre-labeled with a fluorescent dye to allow their discrimination from the effector cells (NK cells). After the incubation period, killed target cells are identified by a nucleic acid stain, which specifically permeates dead cells. This method is amenable to both diagnostic and research applications and, thanks to the multi-parameter capabilities of flow cytometry, has the added advantage of potentially enabling a deeper analysis of NK cell phenotype and function.

Enhancement of Immunotherapies in Head and Neck Cancers Using Biomaterial-Based Treatment Strategies

Head and neck squamous cell carcinoma (HNSCC) is a challenging disease to treat because of typically late-stage diagnoses and tumor formation in difficult-to-treat areas, sensitive to aggressive or invasive treatments. To date, HNSCC treatments have been limited to surgery, radiotherapy, and chemotherapy, which may have significant morbidity and often lead to long-lasting side effects. The development of immunotherapies has revolutionized cancer treatment by providing a promising alternative to standard-of-care therapies. However, single-agent immunotherapy has been only modestly effective in the treatment of various cancers, including HNSCC, with most patients receiving no overall benefit or increased survival. In addition, single-agent immunotherapy's limitations, namely immune-related side effects and the necessity of multidose treatments, must be addressed to further improve treatment efficacy. Biocompatible biomaterials, in combination with cancer immunotherapies, offer numerous advantages in the concentration, localization, and controlled release of drugs, cancer antigens, and immune cells. Biomaterial structures are diverse, and their design can generally be customized to enhance immunotherapy response. In preclinical settings, the use of biomaterials has shown great promise in improving the efficacy of single-agent immunotherapy. Herein, we provide an overview of current immunotherapy treatments for HNSCC and their limitations, as well as the potential applications of biomaterials in enhancing cancer immunotherapies. Impact Statement Advances in anticancer immunotherapies for the past 30 years have yielded exciting clinical results and provided alternatives to long-standing standard-of-care treatments, which are associated with significant toxicities and long-term morbidity. However, patients with head and neck squamous cell carcinoma (HNSCC) have not benefited from immunotherapies as much as patients with other cancers. Immunotherapy limitations include systemic side effects, therapeutic resistance, poor delivery kinetics, and limited patient responses. Biomaterial-enhanced immunotherapies, as explored in this review, are a potentially powerful means of achieving localized drug delivery, sustained and controlled drug release, and immunomodulation. They may overcome current treatment limitations and improve patient outcomes and care.

Localized intratumoral delivery of immunomodulators for oral cancer and oral potentially malignant disorders

Immunotherapy has developed into an important modality of modern cancer treatment. Unfortunately, checkpoint inhibitor immunotherapies are currently delivered systemically and require frequent administration, which can result in toxicity and severe, sometimes fatal, adverse events. Localized delivery of immunomodulators for oral cancer and oral potentially malignant disorders offers the promise of maximum therapeutic potential and reduced systemic adverse effects. This review will discuss the limitations of current standard-of-care systemic therapies and highlight research advances in localized, intratumoral delivery platforms for immunotherapy for oral cancer and oral potentially malignant disorders.