Immunotherapy has become an important part of the oncotherapy arsenal. Its applicability in various cancer types is impressive, as well as its use of endogenous mechanisms to achieve desired ends. However, off-target or on-target-off-tumor toxicity, limited activity, lack of control in combination treatments and, especially for solid tumors, low local accumulation, have collectively limited clinical use thereof. These limitations are partially alleviated by delivery systems. Lipid-based nanoparticles (NPs) have emerged as revolutionary carriers due to favorable physicochemical characteristics, with specific applications and strengths particularly useful in immunotherapeutic agent delivery. The aim of this review is to highlight the challenges faced by immunotherapy and how lipid-based NPs have been, and may be further utilized to address such challenges. We discuss recent fundamental and clinical applications of NPs in a range of areas and provide a detailed discussion of the main obstacles in immune checkpoint inhibition therapies, adoptive cellular therapies, and cytokine therapies. We highlight how lipid-based nanosystems could address these through either delivery, direct modulation of the immune system, or targeting of the immunosuppressive tumor microenvironment. We explore advanced and emerging liposomal and lipid nanoparticle (LNP) systems for nucleic acid delivery, intrinsic and extrinsic stimulus-responsive formulations, and biomimetic lipid-based nanosystems in immunotherapy. Finally, we discuss the key challenges relating to the clinical use of lipid-based NP immunotherapies, suggesting future research directions for the near term to realize the potential of these innovative lipid-based nanosystems, as they become the crucial steppingstone towards the necessary enhancement of the efficacy of immunotherapy. Graphical abstract

Cancer immunotherapy, a promising and widely applied mode of oncotherapy, makes use of immune stimulants and modulators to overcome the immune dysregulation present in cancer, and leverage the host’s immune capacity to eliminate tumors. Although some success has been seen in this field, toxicity and weak immune induction remain challenges. Liposomal nanosystems, previously used as targeting agents, are increasingly functioning as immunotherapeutic vehicles, with potential for delivery of contents, immune induction, and synergistic drug packaging. These systems are tailorable, multifunctional, and smart. Liposomes may deliver various immune reagents including cytokines, specific T-cell receptors, antibody fragments, and immune checkpoint inhibitors, and also present a promising platform upon which personalized medicine approaches can be built, especially with preclinical and clinical potentials of liposomes often being frustrated by inter- and intrapatient variation. In this review, we show the potential of liposomes in cancer immunotherapy, as well as the methods for synthesis and in vivo progression thereof. Both preclinical and clinical studies are included to comprehensively illuminate prospects and challenges for future research and application.

Cervical cancer is the fourth most common cancer in women worldwide and is caused by persistent infection with high‐risk types of human papillomavirus (HPV). HPV viral load, the amount of HPV DNA in a sample, has been suggested to correlate with cervical disease severity, and with clinical outcome of cervical cancer. In this systematic review, we searched three databases (EMBASE, PubMed, Web of Science) to examine the current evidence on the association between HPV viral load in cervical samples and disease severity, as well as clinical outcome. After exclusion of articles not on HPV, cervical cancer, or containing clinical outcomes, 85 original studies involving 173 746 women were included. The vast majority (73/85 = 85.9%) reported that a higher viral load was correlated with higher disease severity or worse clinical outcome. Several studies reported either no correlation (3/85 = 3.5%), or the opposite correlation (9/85 = 10.6%); possible reasons being different categorization of HPV viral load levels, or the use of specific sampling methods. Despite variations in study design and populations, the above findings suggest that HPV viral load is correlated to clinical outcome, and may become an important biomarker for treatment selection and response monitoring for cervical cancer.

Nanomedicines represent theragnostic alternatives to traditional candidate drugs, with increased targeting and delivery potential due to their size and functional tailorability. Biological activity typically relies on nanomaterials permeating into the intracellular environment, necessitating characterization of uptake and intracellular trafficking pathways. Spheroids’ three-dimensional architecture and heterogenous cellular distribution offer an in-vivo-representative platform to assess the biological activity of nanoparticles (NPs). This study aimed to develop an A549 alveolar carcinoma spheroid model as a NP uptake assessment platform for carboxyl–polythene glycol-functionalized gold NPs affording further biological characterization opportunities in nanomedicine. A549 spheroids were generated via the liquid overlay method, and their morphology and viability were assessed for 21 days. Cytotoxicity was assessed via lactate dehydrogenase release. NP uptake was elucidated using uptake pathway inhibition, combined with CytoViva hyperspectral imaging of sectioned spheroids to count internalized NPs. Cytotoxicity was absent for all exposure groups. Clathrin-mediated endocytosis was the primary endocytic mechanism (33.5–54.8% of uptake), which may precede lysosomal degradation. Lysosomal membrane permeabilization appears to be a potential downstream application. Low penetration into spheroids (4.5 μm) suggests the failure of NPs to traverse cellular layers in the spheroid. Although poor uptake was observed, a multicellular spheroid model of A549 alveolar carcinoma cells was established, allowing for similar future uptake assessment of various NPs.

Human papillomavirus (HPV) infection is the primary cause of cervical cancer. Higher viral load, that is, a greater abundance of HPV DNA in a tumor, has been associated with poorer clinical outcomes, and may play a role in the more accurate prediction of (non-) responders to treatment. In this study, we investigated the correlation between HPV viral load, clinical outcomes, and immune parameters related to HPV infection. HPV viral load was quantified using quantitative polymerase chain reaction on biopsies from a prospective cohort of women diagnosed with cervical cancer. Patients were categorized into 2 HPV viral load groups based on the optimal fit of a non-linear piecewise regression model. Immunohistochemical staining was used to measure tumor cell characteristics (Ki67, p16^INK4a, Pan-CK), as well as local tumor immune parameters (CD3, CD4, CD8, FOXP3) and immune checkpoint expression (PD-1, PD-L1). Kaplan-Meier curves were generated to compare recurrence-free and overall survival. In the 44 women included in our study, high HPV viral load was significantly associated with shorter overall and recurrence-free survival (p = .045 and p = .046, respectively; 2-sided) and positively correlated with an increased risk of lymph node and distant metastasis. In addition, a high HPV viral load was linked to lower percentages of tumor-infiltrating lymphocytes and reduced expression levels of PD-1 and PD-L1. The viral load of HPV in cervical cancer correlates positively to metastasis and recurrence and negatively to survival rates, potentially because of local immune suppression. These results might indicate a lower response to immune checkpoint inhibition in the high viral load group and that other treatment options should still be explored.

Gold nanoparticles (AuNPs) present with unique physicochemical features and potential for functionalization as anticancer agents. Three‐dimensional spheroid models can be used to afford greater tissue representation due to their heterogeneous phenotype and complex molecular architecture. This study developed an A549 alveolar carcinoma spheroid model for cytotoxicity assessment and mechanistic evaluation of functionalized AuNPs. A549 spheroids were generated using an agarose micro‐mold and were characterized (morphology, acid phosphatase activity, protein content) over 21 culturing days. The 72‐h cytotoxicity of carboxyl‐polyethylene glycol‐ (PCOOH‐) and amine‐polyethylene glycol‐ (PNH₂‐) functionalized AuNPs against Day 7 spheroids was assessed by determining spheroid morphology, acid phosphatase activity, protein content, caspase‐3/7 activity, and cell cycle kinetics. Spheroids remained stable over the experimental period. Although the A549 spheroids' volume increased while remaining viable over the culturing period, structural integrity decreased from Day 14 onwards. The PCOOH‐AuNPs lacked cytotoxicity at a maximum concentration of 1.2 × 10¹² nanoparticles/mL with no prominent alteration to the cellular processes investigated, while the PNH₂‐AuNPs (at a maximum of 4.5 × 10¹² nanoparticles/mL) displayed dose‐ and time‐dependent cytotoxicity with associated loss of spheroid compactness, debris formation, DNA fragmentation, and a 75% reduction in acid phosphatase activity. Differentiation between cytotoxic and non‐cytotoxic AuNPs was achieved, with preliminary elucidation of cytotoxicity endpoints. The PNH₂‐AuNPs promote cytotoxicity by modulating cellular kinetics while destabilizing the spheroid ultrastructure. The model serves as a proficient platform for more in‐depth elucidation of NP cytotoxicity at the preclinical investigation phase.