Microphysiological systems for solid tumor immunotherapy: opportunities and challenges

Tumoral Pharmacokinetic-Pharmacodynamic Simulation of Doxorubicin-Encapsulated Polymeric Micelles Using a Tissue-Isolated Tumor Perfusion System

Pharmacokinetic (PK) elucidation of polymeric micelles delivering anticancer drugs is crucial for accurate antitumor PK-pharmacodynamic (PK-PD) simulations. Particularly, establishing a methodology to quantify the tumor inflow and outflow of anticancer drugs encapsulated in polymeric micelles is an essential challenge. General tumor biodistribution experiments are disadvantageous in that inflow quantification is easy, but outflow quantification is challenging. We addressed this issue by proposing a quantification method that combines a tissue-isolated tumor perfusion system with microdialysis. This method aims to determine tumoral drug inflow and outflow by quantifying the drugs released from the polymeric micelles via a tumor-embedded microdialysis probe and perfusate, respectively. Furthermore, we evaluated the feasibility of this method by perfusing pH-sensitive polyethylene glycol-poly(aspartate-hydrazone-doxorubicin/phenylalanine)n (PPDF-Hyd-DOX) in a tissue-isolated tumor perfusion system, and we quantified tumor inflow and outflow released DOX. Based on the quantitative results, we performed compartmental analyses by incorporating the gamma-distributed delay function and calculated the PK rate constants. These parameters were input into a tumor-bearing rat compartment model for ex vivo-in vivo extrapolation (EVIVE) of the rat plasma PPDF-Hyd-DOX concentrations and simulated intratumorally released DOX concentrations. The simulation profiles demonstrated a good fit with the Walker 256 intratumoral released DOX concentration profiles previously reported. This EVIVE-PK model was coupled with the threshold natural-growth tumor PD model, and PK-PD analysis was performed. This model exhibited a better fit to the tumor weight profile of Walker 256-bearing rats treated with PPDF-Hyd-DOX than that of our previously reported PK-PD model. Thus, EVIVE, based on a tissue-isolated tumor perfusion system with microdialysis, is a promising approach for the PK-PD simulation of polymeric micelle anticancer therapy.

Dynamic microphysiological system chip platform for high-throughput, customizable, and multi-dimensional drug screening

Spheroids and organoids have attracted significant attention as innovative models for disease modeling and drug screening. By employing diverse types of spheroids or organoids, it is feasible to establish microphysiological systems that enhance the precision of disease modeling and offer more dependable and comprehensive drug screening. High-throughput microphysiological systems that support optional, parallel testing of multiple drugs have promising applications in personalized medical treatment and drug research. However, establishing such a system is highly challenging and requires a multidisciplinary approach. This study introduces a dynamic Microphysiological System Chip Platform (MSCP) with multiple functional microstructures that encompass the mentioned advantages. We developed a high-throughput lung cancer spheroids model and an intestine-liver-heart-lung cancer microphysiological system for conducting parallel testing on four anti-lung cancer drugs, demonstrating the feasibility of the MSCP. This microphysiological system combines microscale and macroscale biomimetics to enable a comprehensive assessment of drug efficacy and side effects. Moreover, the microphysiological system enables evaluation of the real pharmacological effect of drug molecules reaching the target lesion after absorption by normal organs through fluid-based physiological communication. The MSCP could serves as a valuable platform for microphysiological system research, making significant contributions to disease modeling, drug development, and personalized medical treatment.

Rewiring the T cell-suppressive cytokine landscape of the tumor microenvironment: a new frontier for precision anti-cancer therapy

T lymphocytes that infiltrate the tumor microenvironment (TME) often fail to function as effective anti-cancer agents. Within the TME, cell-to-cell inhibitory interactions play significant roles in dampening their anti-tumor activities. Recent studies have revealed that soluble factors released in the TME by immune and non-immune cells, as well as by tumor cells themselves, contribute to the exacerbation of T cell exhaustion. Our understanding of the cytokine landscape of the TME, their interrelationships, and their impact on cancer development is still at its early stages. In this review, we aim to shed light on Interleukin (IL) -6, IL-9, and IL-10, a small group of JAK/STAT signaling-dependent cytokines harboring T cell-suppressive effects in the TME and summarize their mechanisms of action. Additionally, we will explore how advancements in scientific research can help us overcoming the obstacles posed by cytokines that suppress T cells in tumors, with the ultimate objective of stimulating further investigations for the development of novel therapeutic strategies to counteract their tumor-promoting activities.

Tumor-On-A-Chip Models for Predicting In Vivo Nanoparticle Behavior

Nanosized drug formulations are broadly explored for the improvement of cancer therapy. Prediction of in vivo nanoparticle (NP) behavior, however, is challenging, given the complexity of the tumor and its microenvironment. Microfluidic tumor-on-a-chip models are gaining popularity for the in vitro testing of nanoparticle targeting under conditions that simulate the 3D tumor (microenvironment). In this review, following a description of the tumor microenvironment (TME), the state of the art regarding tumor-on-a-chip models for investigating nanoparticle delivery to solid tumors is summarized. The models are classified based on the degree of compartmentalization (single/multi-compartment) and cell composition (tumor only/tumor microenvironment). The physiological relevance of the models is critically evaluated. Overall, microfluidic tumor-on-a-chip models greatly improve the simulation of the TME in comparison to 2D tissue cultures and static 3D spheroid models and contribute to the understanding of nanoparticle behavior. Interestingly, two interrelated aspects have received little attention so far which are the presence and potential impact of a protein corona as well as nanoparticle uptake through phagocytosing cells. A better understanding of their relevance for the predictive capacity of tumor-on-a-chip systems and development of best practices will be a next step for the further refinement of advanced in vitro tumor models.

Pharmacokinetic-Pharmacodynamic Analysis of pH-Responsive Doxorubicin-Releasing Micelles with Anticancer Activity

This study aimed to investigate the effect of in vivo pH-responsive doxorubicin (DOX) release and the targetability of pilot molecules in folic acid (FA)-modified micelles using a pharmacokinetic-pharmacodynamic (PK-PD) model. The time profiles of intratumoral DOX concentrations in Walker256 tumor-bearing rats were monitored using a microdialysis probe, followed by compartmental analysis, to evaluate intratumoral tissue pharmacokinetics. Maximal DOX was released from micelles 350 min after the administration of pH-responsive DOX-releasing micelles. However, FA modification of the micelles shortened the time to peak drug concentration to 150 min. Additionally, FA modification resulted in a 27-fold increase in the tumor inflow rate constant. Walker256 tumor-bearing rats were subsequently treated with DOX, pH-responsive DOX-releasing micelles, and pH-responsive DOX-releasing FA-modified micelles to monitor the tumor growth-time profiles. An intratumoral threshold concentration of DOX (55-64 ng/g tumor) was introduced into the drug efficacy compartment to construct a PD model, followed by PK-PD analysis of the tumor growth-time profiles. Similar results of threshold concentration and drug potency of DOX were obtained across all three formulations. Cell proliferation was delayed as the drug delivery ability of DOX was improved. The PK model, which was developed using the microdialysis method, revealed the intratumoral pH-responsive DOX distribution profiles. This facilitated the estimation of intratumoral PK parameters. The PD model with threshold concentrations contributed to the estimation of PD parameters in the three formulations, with consistent mechanisms observed. We believe that our PK-PD model can objectively assess the contributions of pH-responsive release ability and pilot molecule targetability to pharmacological effects.

Peptide nanovaccine in melanoma immunotherapy

Melanoma is an especially fatal neoplasm resistant to traditional treatment. The advancement of novel therapeutical approaches has gained attention in recent years by shedding light on the molecular mechanisms of melanoma tumorigenesis and their powerful interplay with the immune system. The presence of many mutations in melanoma cells results in the production of a varied array of antigens. These antigens can be recognized by the immune system, thereby enabling it to distinguish between tumors and healthy cells. In the context of peptide cancer vaccines, generally, they are designed based on tumor antigens that stimulate immunity through antigen-presenting cells (APCs). As naked peptides often have low potential in eliciting a desirable immune reaction, immunization with such compounds usually necessitates adjuvants and nanocarriers. Actually, nanoparticles (NPs) can provide a robust immune response to peptide-based melanoma vaccines. They improve the directing of peptide vaccines to APCs and induce the secretion of cytokines to get maximum immune response. This review provides an overview of the current knowledge of the utilization of nanotechnology in peptide vaccines emphasizing melanoma, as well as highlights the significance of physicochemical properties in determining the fate of these nanovaccines in vivo, including their drainage to lymph nodes, cellular uptake, and influence on immune responses.