Targeted delivery of HSP90 inhibitors for efficient therapy of CD44-positive acute myeloid leukemia and solid tumor-colon cancer.

Heat shock protein 90 (HSP90) is overexpressed in numerous cancers, promotes the maturation of numerous oncoproteins and facilitates cancer cell growth. Certain HSP90 inhibitors have entered clinical trials. Although less than satisfactory clinical effects or insurmountable toxicity have compelled these trials to be terminated or postponed, these results of preclinical and clinical studies demonstrated that the prospects of targeting therapeutic strategies involving HSP90 inhibitors deserve enough attention. Nanoparticulate-based drug delivery systems have been generally supposed as one of the most promising formulations especially for targeting strategies. However, so far, no active targeting nano-formulations have succeeded in clinical translation, mainly due to complicated preparation, complex formulations leading to difficult industrialization, incomplete biocompatibility or nontoxicity. In this study, HSP90 and CD44-targeted A6 peptide functionalized biomimetic nanoparticles (A6-NP) was designed and various degrees of A6-modification on nanoparticles were fabricated to evaluate targeting ability and anticancer efficiency. With no excipients, the hydrophobic HSP90 inhibitor G2111 and A6-conjugated human serum albumin could self-assemble into nanoparticles with a uniform particle size of approximately 200 nm, easy fabrication, well biocompatibility and avoidance of hepatotoxicity. Besides, G2111 encapsulated in A6-NP was only released less than 5% in 12 h, which may avoid off-target cell toxicity before entering into cancer cells. A6 peptide modification could significantly enhance uptake within a short time. Moreover, A6-NP continues to exert the broad anticancer spectrum of Hsp90 inhibitors and displays remarkable targeting ability and anticancer efficacy both in hematological malignancies and solid tumors (with colon tumors as the model cancer) both in vitro and in vivo. Overall, A6-NP, as a simple, biomimetic and active dual-targeting (CD44 and HSP90) nanomedicine, displays high potential for clinical translation.

Enhanced Cancer-targeted Drug Delivery Using Precoated Nanoparticles.

While protein coronas (PCs) are an important barrier in the clinical application of nanomedicines, the specific effects of PCs on nanoparticles (NPs) in vivo are unclear. Herein, we demonstrated that PCs from clinical sources greatly influenced the active targeting capacities of transferrin-modified NPs (Tf-NPs). Compared to PCs from healthy volunteers, PCs from the plasma of patients with nonsmall cell lung cancer (NSCLC) decreased the A549 uptake of Tf-NPs to a greater degree. The PC proteome revealed that this difference may be mediated by certain proteins in plasma. To attenuate the negative influence of PCs from patients, precoating Tf-NPs with PCs derived from healthy mice significantly enhanced active targeting capacities. Paclitaxel-loaded Tf-NPs with PCs derived from healthy mice showed the strongest antitumor effects in mice with NSCLC. This work illustrates the influence of PCs of ligand-modified NPs in clinical practice and proposes the use of corona-enabled active targeting for precision nanomedicine.

Combination drug delivery via multilamellar vesicles enables targeting of tumor cells and tumor vasculature.

Blood vessel development is critical for the continued growth and progression of solid tumors and, therefore, makes an attractive target for improving cancer therapy. Indeed, vascular-targeted therapies have been extensively explored but they have shown minimal efficacy as monotherapies. Combretastatin A4 (CA-4) is a tubulin-binding vascular disrupting agent that selectively targets the established tumor endothelium, causing rapid vascular beak down. Despite its potent anticancer potential, the drug has dose-limiting side effects, particularly in the form of cardiovascular toxicity. Furthermore, its poor aqueous solubility and the resulting limited bioavailability hinder its antitumor activity in the clinic. To improve the therapeutic efficacy of CA-4, we investigated its application as a combination therapy with doxorubicin (Dox) in a tumor vasculature targeted delivery vehicle: peptide-modified cross-linked multilamellar liposomal vesicles (cMLVs). In vitro cell culture studies showed that a tumor vasculature-targeting peptide, RIF7, could facilitate higher cellular uptake of drug-loaded cMLVs, and consequently enhance the antitumor efficacy in both drug resistant B16 mouse melanoma and human MDA-MB-231 breast cancer cells. In vivo, upon intravenous injection, targeted cMLVs could efficiently deliver both Dox and CA-4 to significantly slow tumor growth through the specific interaction of the targeting peptide with its receptor on the surface of tumor vasculature. This study demonstrates the potential of our novel targeted combination therapy delivery vehicle to improve the outcome of cancer treatment.

Transport Mechanisms of Butyrate Modified Nanoparticles: Insight into "Easy Entry, Hard Transcytosis" of Active Targeting System in Oral Administration.

The intestinal epithelium constitutes a major barrier for orally delivered nanoparticles (NPs). Although surface ligand modification can increase cellular uptake of NPs, the transepithelial transport of active targeting NPs is relatively limited. The phenomenon is described as "easy entry, hard transcytosis". However, underlying mechanisms and potential solutions of this phenomenon are unclear. Here, butyrate modified polyethylene glycol coated NPs (Bu-PEG NPs) were chosen as the model active targeting NPs. Transport mechanism studies were performed to get a better understanding of intracellular trafficking and exocytosis fate. Results showed that after active binding to monocarboxylate transporter-1 (MCT-1), Bu-PEG NPs went through endolysosomal pathways, endoplasmic reticulum/Golgi recycling routes, and microtubule-dependent shuttling within Caco-2 cells. Then a larger proportion of Bu-PEG NPs was exocytosed from apical side. Notably, increasing the basal expression of MCT-1 by leptin facilitated basal exocytosis and transcytosis of Bu-PEG NPs, which confirmed that enhanced receptor recognition could promote "basal exit". In addition to the effect of receptor recognition, surface properties also influenced the bidirectional exocytosis of Bu-PEG NPs. When surface hydrophobicity increased, Bu-PEG NPs were dominantly exocytosed from basal membrane. Hence, two strategies may help to overcome "hard transcytosis" of active targeting NPs. One is to enhance their affinity with basal membrane by reinforcing the receptor-ligand interaction; the other is to weaken apical exocytosis by optimizing surface hydrophobicity. Thereby, this study might provide important implications for the rational design of NPs to further increase transepithelial transport efficiency.

DR5 mAb-conjugated, DTIC-loaded immuno-nanoparticles effectively and specifically kill malignant melanoma cells in vivo.

We combined chemo- and immunotherapies by constructing dual therapeutic function immuno-nanoparticles (NPs) consisting of death receptor 5 monoclonal antibody (DR5 mAb)-conjugated nanoparticles loaded with dacarbazine (DTIC) (DTIC-NPs-DR5 mAb). We determined the in vivo targeting specificity of DTIC-NPs-DR5 mAb by evaluating distribution in tumor-bearing nude mice using a real-time imaging system. Therapeutic efficacy was assessed in terms of its effect on tumor volume, survival time, histomorphology, microvessel density (MVD), and apoptotic index (AI). Systemic toxicity was evaluated by measuring white blood cells (WBC) counts, alanine aminotransferase (ALT) levels, and creatinine clearance (CR).In vivo and ex vivo imaging indicates that DR5 mAb modification enhanced the accumulation of NPs within the xenograft tumor. DTIC-NPs-DR5 mAb inhibited tumor growth more effectively than DTIC or DR5 mAb alone, indicating that combining DTIC and DR5 mAb through pharmaceutical engineering achieves a better therapeutic effect. Moreover, the toxicity of DTIC-NPs-DR5 mAb was much lower than that of DTIC, implying that DR5 mAb targeting reduces nonspecific uptake of DTIC into normal tissue and thus decreases toxic side effects. These results demonstrate that DTIC-NPs-DR5 mAb is a safe and effective nanoparticle formulation with the potential to improve the efficacy and specificity of melanoma treatment.

Combined Tumor- and Neovascular-"Dual Targeting" Gene/Chemo-Therapy Suppresses Tumor Growth and Angiogenesis.

A rational combination is critical to achieve efficiently synergistic therapeutic efficacy for tumor treatment. Hence, we designed novel antitumor combinations (T-NPs) by integrating the tumor vascular and tumor cells dual-targeting ligand with antiangiogenesis/antitumor agents. The truncated bFGF peptide (tbFGF), which could effectively bind to FGFR1 overexpressed on tumor neovasculature endothelial cells and tumor cells, was selected to modify PLGA nanoparticles (D/P-NPs) simultaneously loaded with PEDF gene and paclitaxel in this study. The obtained T-NPs with better pharmaceutical properties had elevated cytotoxicity and enhanced expression of PEDF and α-tubulin on FGFR1-overexpressing cells. The uptake of T-NPs increased in C26 cells, probably mediated by tbFGF via specific recognization of the overexpressed FGFR1. T-NPs dramatically disrupted the tube formation of primary human umbilical vein endothelial cells (HUVECs) and displayed improved antiangiogenic activity in the transgenic zebrafish model and the alginate-encapsulated tumor cell model. More importantly, T-NPs achieved a markedly higher antitumor efficacy in the C26 tumor-bearing mice model. The antitumor effect involved the inhibition of tumor cell proliferation and angiogenesis, induction of apoptosis, and down-regulation of FGFR1. The enhanced antitumor activity of T-NPs probably resulted from the raised distribution in tumor tissues. In addition, T-NPs had no obvious toxicity as evaluated by weight monitoring, serological/biochemical analyses, and H&E staining. These results revealed that T-NPs, an active targeting gene/chemo-therapy, indeed had superior antitumor efficacy and negligible side effect, suggesting that this novel combination is a potential tumor therapy and a new treatment strategy and that the tbFGF modified nanoparticles could be applied to a wide range of tumor-genetic therapies and/or tumor-chemical therapies.

Anti-DR5 monoclonal antibody-mediated DTIC-loaded nanoparticles combining chemotherapy and immunotherapy for malignant melanoma: target formulation development and in vitro anticancer activity.

BACKGROUND: The increased incidence of malignant melanoma in recent decades, along with its high mortality rate and pronounced resistance to therapy pose an enormous challenge. Novel therapeutic strategies, such as immunotherapy and targeted therapy, are urgently needed for melanoma. In this study, a new active targeting drug delivery system was constructed to combine chemotherapy and active specific immunotherapy. METHODS: The chemotherapeutic drug, dacarbazine (DTIC), that induces apoptosis through the intrinsic pathway which typically responds to severe DNA damage, was used as a model drug to prepare DTIC-loaded polylactic acid (PLA) nanoparticles (DTIC-NPs), which were covalently conjugated to a highly specific targeting functional TRAIL-receptor 2 (DR5) monoclonal antibody (mAb) that can contribute directly to cancer cell apoptosis or growth inhibition through the extrinsic pathway. RESULTS: Our in vitro experiments demonstrated that DTIC-PLA-DR5 mAb nanoparticles (DTIC-NPs-DR5 mAb) are an active targeting drug delivery system which can specifically target DR5-overexpressing malignant melanoma cells and become efficiently internalized. Most strikingly, compared with conventional DTIC-NPs, DTIC-NPs-DR5 mAb showed significantly enhanced cytotoxicity and increased cell apoptosis in DR5-positive malignant melanoma cells. CONCLUSION: The DTIC-NPs-DR5 mAb described in this paper might be a potential formulation for targeting chemotherapy and immunotherapy to DR5-overexpressing metastatic melanoma.