Explore the vast range of titles available.

Nanoparticle-based experimental therapeutics are currently being investigated in numerous human clinical trials. CALAA-01 is a targeted, polymer-based nanoparticle containing small interfering RNA (siRNA) and, to our knowledge, was the first RNA interference (RNAi)—based, experimental therapeutic to be administered to cancer patients. Here, we report the results from the initial phase I clinical trial where 24 patients with different cancers were treated with CALAA-01 and compare those results to data obtained from multispecies animal studies to provide a detailed example of translating this class of nanoparticles from animals to humans. The pharmacokinetics of CALAA-01 in mice, rats, monkeys, and humans show fast elimination and reveal that the maximum concentration obtained in the blood after i.v. administration correlates with body weight across all species. The safety profile of CALAA-01 in animals is similarly obtained in humans except that animal kidney toxicities are not observed in humans; this could be due to the use of a predosing hydration protocol used in the clinic. Taken in total, the animal models do appear to predict the behavior of CALAA-01 in humans.

Nanoparticles are being investigated for numerous medical applications and are showing potential as an emerging class of carriers for drug delivery. Investigations on how the physicochemical properties (e.g., size, surface charge, shape, and density of targeting ligands) of nanoparticles enable their ability to overcome biological barriers and reach designated cellular destinations in sufficient amounts to elicit biological efficacy are of interest. Despite proven success in nanoparticle accumulation at cellular locations and occurrence of downstream therapeutic effects (e.g., target gene inhibition) in a selected few organs such as tumor and liver, reports on effective delivery of engineered nanoparticles to other organs still remain scarce. Here, we show that nanoparticles of ~75 ± 25-nm diameters target the mesangium of the kidney. These data show the effects of particle diameter on targeting the mesangium of the kidney. Because many diseases originate from this area of the kidney, our findings establish design criteria for constructing nanoparticle-based therapeutics for targeting diseases that involve the mesangium of the kidney.

Despite being engineered to avoid renal clearance, many cationic polymer (polycation)-based siRNA nanoparticles that are used for systemic delivery are rapidly eliminated from the circulation. Here, we show that a component of the renal filtration barrier—the glomerular basement membrane (GBM)—can disassemble cationic cyclodextrin-containing polymer (CDP)-based siRNA nanoparticles and, thereby, facilitate their rapid elimination from circulation. Using confocal and electron microscopies, positron emission tomography, and compartment modeling, we demonstrate that siRNA nanoparticles, but not free siRNA, accumulate and disassemble in the GBM. We also confirm that the siRNA nanoparticles do not disassemble in blood plasma in vitro and in vivo. This clearance mechanism may affect any nanoparticles that assemble primarily by electrostatic interactions between cationic delivery components and anionic nucleic acids (or other therapeutic entities).

Human RNAi therapy The ability to downregulate specific genes using systemically delivered short RNA molecules and the cellular mechanism known as RNA interference has been shown previously in mouse and non-human primate models. Davis et al . have now demonstrated for the first time in humans that a short interfering RNA (siRNA) molecule can be systemically delivered using nanoparticles to a solid tumour. The siRNA mediates directed cleavage of its target mRNA, thereby also reducing the protein level. This proof-of-principle study confirms the potential of this technology as a human therapeutic. It has previously been shown in mice and non-human primates that systemically delivered short RNA molecules can inhibit gene expression. Here it is shown that a short interfering RNA (siRNA) can be systemically delivered, using nanoparticles, to a solid tumour in humans. The siRNA mediates cleavage of its target mRNA, thereby also reducing levels of the encoded protein. This proof-of-principle study confirms the potential of this technology for treating human disease. Therapeutics that are designed to engage RNA interference (RNAi) pathways have the potential to provide new, major ways of imparting therapy to patients 1 , 2 . Long, double-stranded RNAs were first shown to mediate RNAi in Caenorhabditis elegans 3 , and the potential use of RNAi for human therapy has been demonstrated by the finding that small interfering RNAs (siRNAs; approximately 21-base-pair double-stranded RNA) can elicit RNAi in mammalian cells without producing an interferon response 4 . We are at present conducting the first in-human phase I clinical trial involving the systemic administration of siRNA to patients with solid cancers using a targeted, nanoparticle delivery system. Here we provide evidence of inducing an RNAi mechanism of action in a human from the delivered siRNA. Tumour biopsies from melanoma patients obtained after treatment show the presence of intracellularly localized nanoparticles in amounts that correlate with dose levels of the nanoparticles administered (this is, to our knowledge, a first for systemically delivered nanoparticles of any kind). Furthermore, a reduction was found in both the specific messenger RNA (M2 subunit of ribonucleotide reductase ( RRM2 )) and the protein (RRM2) levels when compared to pre-dosing tissue. Most notably, we detect the presence of an mRNA fragment that demonstrates that siRNA-mediated mRNA cleavage occurs specifically at the site predicted for an RNAi mechanism from a patient who received the highest dose of the nanoparticles. Together, these data demonstrate that siRNA administered systemically to a human can produce a specific gene inhibition (reduction in mRNA and protein) by an RNAi mechanism of action.

Traditional histochemical staining of post-mortem samples often confronts inferior staining quality due to autolysis caused by delayed fixation of cadaver tissue, and such chemical staining procedures covering large tissue areas demand substantial labor, cost and time. Here, we demonstrate virtual staining of autopsy tissue using a trained neural network to rapidly transform autofluorescence images of label-free autopsy tissue sections into brightfield equivalent images, matching hematoxylin and eosin (H&E) stained versions of the same samples. The trained model can effectively accentuate nuclear, cytoplasmic and extracellular features in new autopsy tissue samples that experienced severe autolysis, such as COVID-19 samples never seen before, where the traditional histochemical staining fails to provide consistent staining quality. This virtual autopsy staining technique provides a rapid and resource-efficient solution to generate artifact-free H&E stains despite severe autolysis and cell death, also reducing labor, cost and infrastructure requirements associated with the standard histochemical staining. Conventional staining of post-mortem samples can be affected by several factors, including tissue autolysis. Here, the authors demonstrate a virtual staining tool using a trained neural network to turn autofluorescence images of label-free autopsy tissue into brightfield equivalent images.

The histological analysis of tissue samples, widely used for disease diagnosis, involves lengthy and laborious tissue preparation. Here, we show that a convolutional neural network trained using a generative adversarial-network model can transform wide-field autofluorescence images of unlabelled tissue sections into images that are equivalent to the bright-field images of histologically stained versions of the same samples. A blind comparison, by board-certified pathologists, of this virtual staining method and standard histological staining using microscopic images of human tissue sections of the salivary gland, thyroid, kidney, liver and lung, and involving different types of stain, showed no major discordances. The virtual-staining method bypasses the typically labour-intensive and costly histological staining procedures, and could be used as a blueprint for the virtual staining of tissue images acquired with other label-free imaging modalities. Deep learning can be used to virtually stain autofluorescence images of unlabelled tissue sections, generating images that are equivalent to the histologically stained versions.

Nanoparticles are currently being investigated in a number of human clinical trials. As information on how nanoparticles function in humans is difficult to obtain, animal studies that can be correlative to human behavior are needed to provide guidance for human clinical trials. Here, we report correlative studies on animals and humans for CRLX101, a 20-to 30-nm-diameter, multifunctional, polymeric nanoparticle containing camptothecin (CPT). CRLX101 is currently in phase 2 clinical trials, and human data from several of the clinical investigations are compared with results from multispecies animal studies. The pharmacokinetics of polymer-conjugated CPT (indicative of the CRLX101 nanoparticles) in mice, rats, dogs, and humans reveal that the area under the curve scales linearly with milligrams of CPT per square meter for all species. Plasma concentrations of unconjugated CPT released from CRLX101 in animals and humans are consistent with each other after accounting for differences in serum albumin binding of CPT. Urinary excretion of polymer-conjugated CPT occurs primarily within the initial 24 h after dosing in animals and humans. The urinary excretion dynamics of polymer-conjugated and unconjugated CPT appear similar between animals and humans. CRLX101 accumulates into solid tumors and releases CPT over a period of several days to give inhibition of its target in animal xenograft models of cancer and in the tumors of humans. Taken in total, the evidence provided from animal models on the CRLX101 mechanism of action suggests that the behavior of CRLX101 in animals is translatable to humans.

Key Points Several Phase I trials evaluating the use of siRNA for the treatment of solid cancers have now been completed. All trials to date have used nanoparticle-based delivery systems to transport therapeutic siRNA to tumours following systemic administration. Despite concerns about potential overwhelming immunostimulation following systemic siRNA administration in humans, the data reported to date for clinically evaluated siRNA therapeutics (both naked and chemically modified siRNA) have shown these therapeutics to be well tolerated, with only modest and treatable immunostimulatory reactions. Successful delivery of functional siRNA to human tumours has been demonstrated in multiple trials, providing proof-of-principle for RNAi- based therapeutics in humans. Results from these trials show that safe target gene inhibition can be achieved in patients, when systemically treated twice per week with either lipid- or polymer-based nanoparticle formulations containing siRNAs at doses in the 0.5–1.0 mg siRNA per kg range. Several Phase I trials evaluating systemically administered siRNA-based therapeutics for cancer have recently been completed. Here, Zuckerman and Davis critically assess these studies and discuss key lessons learnt and implications for the future development of siRNA-based therapeutics and clinical trial design. Small interfering RNA (siRNA)-based therapies are emerging as a promising new anticancer approach, and a small number of Phase I clinical trials involving patients with solid tumours have now been completed. Encouraging results from these pioneering clinical studies show that these new therapeutics can successfully and safely inhibit targeted gene products in patients with cancer, and have taught us important lessons regarding appropriate dosages and schedules. In this Review, we critically assess these Phase I studies and discuss their implications for future clinical trial design. Key challenges and future directions in the development of siRNA-containing anticancer therapeutics are also considered.

There is an urgent need for new therapies that can halt or reverse the course of chronic kidney disease with minimal side-effect burden on the patient. Small interfering RNA (siRNA) nanoparticles are new therapeutic entities in clinical development that could be useful for chronic kidney disease treatment because they combine the tissue-specific targeting properties of nanoparticles with the gene-specific silencing effects of siRNA. Recent reports have emerged demonstrating that the kidney, specifically the glomerulus, is a readily accessible site for nanoparticle targeting. Here, we explore the hypothesis that intravenously administered polycationic cyclodextrin nanoparticles containing siRNA (siRNA/CDP-NPs) can be used for delivery of siRNA to the glomerular mesangium. We demonstrate that siRNA/CDP-NPs localize to the glomerular mesangium with limited deposition in other areas of the kidney after intravenous injection. Additionally, we report that both mouse and human mesangial cells rapidly internalize siRNA/CDP-NPs in vitro and that nanoparticle uptake can be enhanced by attaching the targeting ligands mannose or transferrin to the nanoparticle surface. Lastly, we show knockdown of mesangial enhanced green fluorescent protein expression in a reporter mouse strain following iv treatment with siRNA/CDP-NPs. Altogether, these data demonstrate the feasibility of mesangial targeting using intravenously administered siRNA/CDP-NPs.

Idiopathic multicentric Castleman disease (iMCD) is a rare lymphadenopathic disorder characterized by hyperplasia of multiple lymph nodes and can be associated with a wide range of symptoms and presentations, from mild disease to life-threatening organ failure. Varied histopathological features and heterogeneous presentation of this rare entity can make the diagnosis quite challenging for both hematologists and other specialists who may encounter patients at various stages of disease progression. We analyze five different clinical presentations at our institution to demonstrate challenging routes of diagnosis and treatment complexities of iMCD. We aim to raise awareness to the importance of early diagnosis and appropriate management of this rare condition. All patients in this series presented with symptomatic lymphadenopathy. We highlight one rare instance of thrombocytopenia, anasarca/ascites, fever, reticulin fibrosis or renal dysfunction, and organomegaly (TAFRO) syndrome with elusive iMCD, which illustrates the challenges in the diagnosis of this rare condition and the importance of early recognition of its symptoms to avoid decompensation of patients. We also review established treatment guidelines and response criteria to siltuximab as outlined in the international consensus treatment guidelines. These cases highlight the heterogeneity and challenging diagnosis of this rare cytokine-driven hematological disorder and the role of siltuximab in the treatment of iMCD.