Historically, treatment of patients with cancer using chemotherapeutic agents has been associated with debilitating and systemic toxicities, poor bioavailability, and unfavorable pharmacokinetics. Nanotechnology-based drug delivery systems, on the other hand, can specifically target cancer cells while avoiding their healthy neighbors, avoid rapid clearance from the body, and be administered without toxic solvents. They hold immense potential in addressing all of these issues, which has hampered further development of chemotherapeutics. Furthermore, such drug delivery systems will lead to cancer therapeutic modalities that are not only less toxic to the patient but also significantly more efficacious. In addition to established therapeutic modes of action, nanomaterials are opening up entirely new modalities of cancer therapy, such as photodynamic and hyperthermia treatments. Furthermore, nanoparticle carriers are also capable of addressing several drug delivery problems that could not be effectively solved in the past and include overcoming formulation issues, multidrug-resistance phenomenon, and penetrating cellular barriers that may limit device accessibility to intended targets, such as the blood–brain barrier. The challenges in optimizing design of nanoparticles tailored to specific tumor indications still remain; however, it is clear that nanoscale devices carry a significant promise toward new ways of diagnosing and treating cancer. This review focuses on future prospects of using nanotechnology in cancer applications and discusses practices and methodologies used in the development and translation of nanotechnology-based therapeutics. Clin Cancer Res; 18(12); 3229–41. ©2012 AACR.

Nanoparticle (NP) delivery to solid tumors has recently been questioned. To better understand the magnitude of NP tumor delivery, we reanalyzed published murine NP tumor pharmacokinetic (PK) data used in the Wilhelm et al. study. Studies included in their analysis reporting matched tumor and blood concentration versus time data were evaluated using classical PK endpoints and compared to the unestablished percent injected dose (%ID) in tumor metric from the Wilhelm et al. study. The %ID in tumor was poorly correlated with standard PK metrics that describe NP tumor delivery (AUC_tumor/AUC_blood ratio) and only moderately associated with maximal tumor concentration. The relative tumor delivery of NPs was ~100-fold greater as assessed by the standard AUC_tumor/AUC_blood ratio than by %ID in tumor. These results strongly suggest that PK metrics and calculations can influence the interpretation of NP tumor delivery and stress the need to properly validate novel PK metrics against traditional approaches.

Major advances in therapeutic proteins, including antibody–drug conjugates (ADCs), have created revolutionary drug delivery systems in cancer over the past decade. While these immunoconjugate agents provide several advantages compared to their small-molecule counterparts, their clinical use is still in its infancy. The considerations in their development and clinical use are complex, and consist of multiple components and variables that can affect the pharmacologic characteristics. It is critical to understand the mechanisms employed by ADCs in navigating biological barriers and how these factors affect their biodistribution, delivery to tumors, efficacy, and toxicity. Thus, future studies are warranted to better understand the complex pharmacology and interaction between ADC carriers and biological systems, such as the mononuclear phagocyte system (MPS) and tumor microenvironment. This review provides an overview of factors that affect the pharmacologic profiles of ADC therapies that are currently in clinical use and development.

Nanoparticles (NPs) provide several advantages over the small molecule drugs including prolonged circulation time and enhanced delivery to targeted sites. Once a NP enters the body, it interacts with host’s immune system and is engulfed by cells of the mononuclear phagocyte system (MPS). The interaction between NPs and the immune cells can result in immunosuppression or immunostimulation, which may enhance or reduce the treatment effects of NPs. Therefore, it is critical to understand the interactions between NPs and the immune system in order to optimize the treatment benefit and minimize the undesirable toxicities of NPs. This review elaborates on the interaction between NP and the MPS and its impacts on the pharmacokinetics (PK) and pharmacodynamics (PD) of NPs and applications for inflammatory diseases. This review also encompasses an overview of NPs being developed for treatment of inflammatory diseases.

Purpose: Tumor cells are surrounded by a complex microenvironment. The purpose of our study was to evaluate the role of heterogeneity of the tumor microenvironment in the variability of nanoparticle (NP) delivery and efficacy. Experimental Designs: C3(1)-T-Antigen genetically engineered mouse model (C3-TAg) and T11/TP53^Null orthotopic syngeneic murine transplant model (T11) representing human breast tumor subtypes basal-like and claudin-low, respectively, were evaluated. For the pharmacokinetic studies, non-liposomal doxorubicin (NL-doxo) or polyethylene glycol tagged (PEGylated) liposomal doxorubicin (PLD) was administered at 6 mg/kg i.v. x1. Area under the concentration versus time curve (AUC) of doxorubicin was calculated. Macrophages, collagen, and the amount of vasculature were assessed by IHC. Chemokines and cytokines were measured by multiplex immunochemistry. NL-doxo or PLD was administered at 6 mg/kg i.v. weekly x6 in efficacy studies. Analyses of intermediary tumor response and overall survival were performed. Results: Plasma AUC of NL-doxo and PLD encapsulated and released doxorubicin was similar between two models. However, tumor sum total AUC of PLD was 2-fold greater in C3-TAg compared with T11 (P < 0.05). T11 tumors showed significantly higher expression of CC chemokine ligand (CCL) 2 and VEGF-a, greater vascular quantity, and decreased expression of VEGF-c compared with C3-TAg (P < 0.05). PLD was more efficacious compared with NL-doxo in both models. Conclusion: The tumor microenvironment and/or tumor cell features of breast cancer affected NP tumor delivery and efficacy, but not the small-molecule drug. Our findings reveal the role of the tumor microenvironment in variability of NP delivery and therapeutic outcomes. Clin Cancer Res; 20(23); 6083–95. ©2014 AACR.