Photothermal therapy (PTT) has shown significant potential for cancer therapy. However, developing nanomaterials (NMs)-based photothermal agents (PTAs) with satisfactory photothermal conversion efficacy (PTCE) and biocompatibility remains a key challenge. Herein, a new generation of PTAs based on two-dimensional (2D) antimonene quantum dots (AMQDs) was developed by a novel liquid exfoliation method. Surface modification of AMQDs with polyethylene glycol (PEG) significantly enhanced both biocompatibility and stability in physiological medium. The PEG-coated AMQDs showed a PTCE of 45.5%, which is higher than many other NMs-based PTAs such as graphene, Au, MoS2, and black phosphorus (BP). The AMQDs-based PTAs also exhibited a unique feature of NIR-induced rapid degradability. Through both in vitro and in vivo studies, the PEG-coated AMQDs demonstrated notable NIR-induced tumor ablation ability. This work is expected to expand the utility of 2D antimonene (AM) to biomedical applications through the development of an entirely novel PTA platform.

The application of nanoparticles (NPs) to drug delivery has led to the development of novel nanotherapeutics for the treatment of various diseases including cancer. However, clinical use of NP‐mediated drug delivery has not always translated into improved survival of cancer patients, in part due to the suboptimal properties of NP platforms, such as premature drug leakage during preparation, storage, or blood circulation, lack of active targeting to tumor tissue and cells, and poor tissue penetration. Herein, an innovative reactive oxygen species (ROS)‐responsive polyprodrug is reported that can self‐assemble into stable NPs with high drug loading. This new NP platform is composed of the following key components: (i) polyprodrug inner core that can respond to ROS for triggered release of intact therapeutic molecules, (ii) polyethylene glycol (PEG) outer shell to prolong blood circulation; and (iii) surface‐encoded internalizing RGD (iRGD) to enhance tumor targeting and tissue penetration. These targeted ROS‐responsive polyprodrug NPs show significant inhibition of tumor cell growth both in vitro and in vivo.

Antimonene (AM) is a recently described two-dimensional (2D) elemental layered material. In this study, a novel photonic drug-delivery platform based on 2D PEGylated AM nanosheets (NSs) is developed. The platform's multiple advantages include: i) excellent photothermal properties, ii) high drug-loading capacity, iii) spatiotemporally controlled drug release triggered by near-infrared (NIR) light and moderate acidic pH, iv) superior accumulation at tumor sites, v) deep tumor penetration by both extrinsic stimuli (i.e., NIR light) and intrinsic stimuli (i.e., pH), vi) excellent multimodal-imaging properties, and vii) significant inhibition of tumor growth with no observable side effects and potential degradability, thus addressing several key limitations of cancer nanomedicines. The intracellular fate of the prepared NSs is also revealed for the first time, providing deep insights that improve cellular-level understanding of the nano-bio interactions of AM-based NSs and other emerging 2D nanomaterials. To the best of knowledge, this is the first report on 2D AM-based photonic drug-delivery platforms, possibly marking an exciting jumping-off point for research into the application of 2D AM nanomaterials in cancer theranostics.

No abstract

With the capability of specific silencing of target gene expression, RNA interference (RNAi) technology is emerging as a promising therapeutic modality for the treatment of cancer and other diseases. One key challenge for the clinical applications of RNAi is the safe and effective delivery of RNAi agents such as small interfering RNA (siRNA) to a particular nonliver diseased tissue (e.g., tumor) and cell type with sufficient cytosolic transport. In this work, we proposed a multifunctional envelope-type nanoparticle (NP) platform for prostate cancer (PCa)-specific in vivo siRNA delivery. A library of oligoarginine-functionalized and sharp pH-responsive polymers was synthesized and used for self-assembly with siRNA into NPs with the features of long blood circulation and pH-triggered oligoarginine-mediated endosomal membrane penetration. By further modification with ACUPA, a small molecular ligand specifically recognizing prostate-specific membrane antigen (PSMA) receptor, this envelope-type nanoplatform with multifunctional properties can efficiently target PSMA-expressing PCa cells and silence target gene expression. Systemic delivery of the siRNA NPs can efficiently silence the expression of prohibitin 1 (PHB1), which is upregulated in PCa and other cancers, and significantly inhibit PCa tumor growth. These results suggest that this multifunctional envelope-type nanoplatform could become an effective tool for PCa-specific therapy.

The programmed cell death 1 (PD-1) receptor on the surface of immune cells is an immune checkpoint molecule that mediates the immune escape of tumor cells. Consequently, antibodies targeting PD-1 have shown efficacy in enhancing the antitumor activity of T cells in some types of cancers. However, the potential effects of PD-1 on tumor cells remain largely unknown. Here, we show that PD-1 is expressed across a broad range of tumor cells. The silencing of PD-1 or its ligand, PD-1 ligand 1 (PD-L1), promotes cell proliferation and colony formation in vitro and tumor growth in vivo. Conversely, overexpression of PD-1 or PD-L1 inhibits tumor cell proliferation and colony formation. Moreover, blocking antibodies targeting PD-1 or PD-L1 promote tumor growth in cell cultures and xenografts. Mechanistically, the coordination of PD-1 and PD-L1 activates its major downstream signaling pathways including the AKT and ERK1/2 pathways, thus enhancing tumor cell growth. This study demonstrates that PD-1/PD-L1 is a potential tumor suppressor and potentially regulates the response to anti-PD-1/PD-L1 treatments, thus representing a potential biomarker for the optimal cancer immunotherapeutic treatment.

Current antiangiogenic therapy is limited by its cytostatic nature and systemic side effects. To address these limitations, we have unveiled the role of RhoJ, an endothelial-enriched Rho GTPase, during tumor progression. RhoJ blockade provides a double assault on tumor vessels by both inhibiting tumor angiogenesis and disrupting the preformed tumor vessels through the activation of the RhoA-ROCK (Rho kinase) signaling pathway in tumor endothelial cells, consequently resulting in a functional failure of tumor vasculatures. Moreover, enhanced anticancer effects were observed when RhoJ blockade was employed in concert with a cytotoxic chemotherapeutic agent, angiogenesis-inhibiting agent, or vascular-disrupting agent. These results identify RhoJ blockade as a selective and effective therapeutic strategy for targeting tumor vasculature with minimal side effects.

Recently, phage display technology has been announced as the recipient of Nobel Prize in Chemistry 2018. Phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the screening of peptide with high affinity and selectivity. In this review, we will first discuss the modifications in phage display techniques used to isolate various cancer-specific ligands by in situ, in vitro, in vivo, and ex vivo screening methods. We will then discuss prominent examples of solid tumor targeting-peptides; namely peptide targeting tumor vasculature, tumor microenvironment (TME) and over-expressed receptors on cancer cells identified through phage display screening. We will also discuss the current challenges and future outlook for targeting peptide-based therapeutics in the clinics.