This Perspective explores and explains the fundamental dogma of nanoparticle delivery to tumours and answers two central questions: ‘how many nanoparticles accumulate in a tumour?’ and ‘how does this number affect the clinical translation of nanomedicines?’

/pdf/analysis-of-nanoparticle-delivery-to-tumours-kovi4y80u2.pdf

Analysis of nanoparticle delivery to tumours

Extracellular vesicles (EVs) have emerged as important mediators of intercellular communication in a diverse range of biological processes. For future therapeutic applications and for EV biology research in general, understanding the in vivo fate of EVs is of utmost importance. Here we studied biodistribution of EVs in mice after systemic delivery. EVs were isolated from 3 different mouse cell sources, including dendritic cells (DCs) derived from bone marrow, and labelled with a near-infrared lipophilic dye. Xenotransplantation of EVs was further carried out for cross-species comparison. The reliability of the labelling technique was confirmed by sucrose gradient fractionation, organ perfusion and further supported by immunohistochemical staining using CD63-EGFP probed vesicles. While vesicles accumulated mainly in liver, spleen, gastrointestinal tract and lungs, differences related to EV cell origin were detected. EVs accumulated in the tumour tissue of tumour-bearing mice and, after introduction of the rabies virus glycoprotein-targeting moiety, they were found more readily in acetylcholine-receptor-rich organs. In addition, the route of administration and the dose of injected EVs influenced the biodistribution pattern. This is the first extensive biodistribution investigation of EVs comparing the impact of several different variables, the results of which have implications for the design and feasibility of therapeutic studies using EVs.

https://www.tandfonline.com/doi/pdf/10.3402/jev.v4.26316

Extracellular vesicle in vivo biodistribution is determined by cell source, route of administration and targeting

Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell types and participate in physiological and pathophysiological processes. EVs mediate intercellular communication as cell-derived extracellular signalling organelles that transmit specific information from their cell of origin to their target cells. As a result of these properties, EVs of defined cell types may serve as novel tools for various therapeutic approaches, including (a) anti-tumour therapy, (b) pathogen vaccination, (c) immune-modulatory and regenerative therapies and (d) drug delivery. The translation of EVs into clinical therapies requires the categorization of EV-based therapeutics in compliance with existing regulatory frameworks. As the classification defines subsequent requirements for manufacturing, quality control and clinical investigation, it is of major importance to define whether EVs are considered the active drug components or primarily serve as drug delivery vehicles. For an effective and particularly safe translation of EV-based therapies into clinical practice, a high level of cooperation between researchers, clinicians and competent authorities is essential. In this position statement, basic and clinical scientists, as members of the International Society for Extracellular Vesicles (ISEV) and of the European Cooperation in Science and Technology (COST) program of the European Union, namely European Network on Microvesicles and Exosomes in Health and Disease (ME-HaD), summarize recent developments and the current knowledge of EV-based therapies. Aspects of safety and regulatory requirements that must be considered for pharmaceutical manufacturing and clinical application are highlighted. Production and quality control processes are discussed. Strategies to promote the therapeutic application of EVs in future clinical studies are addressed.

/pdf/applying-extracellular-vesicles-based-therapeutics-in-2o6zkamf5c.pdf

Applying extracellular vesicles based therapeutics in clinical trials - an ISEV position paper

The sustained growth, invasion, and metastasis of cancer cells depend upon bidirectional cell-cell communication within complex tissue environments. Such communication predominantly involves the secretion of soluble factors by cancer cells and/or stromal cells within the tumour microenvironment (TME), although these cell types have also been shown to export membrane-encapsulated particles containing regulatory molecules that contribute to cell-cell communication. These particles are known as extracellular vesicles (EVs) and include species of exosomes and shed microvesicles. EVs carry molecules such as oncoproteins and oncopeptides, RNA species (for example, microRNAs, mRNAs, and long non-coding RNAs), lipids, and DNA fragments from donor to recipient cells, initiating profound phenotypic changes in the TME. Emerging evidence suggests that EVs have crucial roles in cancer development, including pre-metastatic niche formation and metastasis. Cancer cells are now recognized to secrete more EVs than their nonmalignant counterparts, and these particles can be isolated from bodily fluids. Thus, EVs have strong potential as blood-based or urine-based biomarkers for the diagnosis, prognostication, and surveillance of cancer. In this Review, we discuss the biophysical properties and physiological functions of EVs, particularly their pro-metastatic effects, and highlight the utility of EVs for the development of cancer diagnostics and therapeutics.

Extracellular vesicles in cancer - implications for future improvements in cancer care.

Extracellular vesicles for drug delivery.

Biodistribution and delivery efficiency of unmodified tumor-derived exosomes.

Ga-68-labeled prostate-specific membrane antigen (PSMA) ligands have been used clinically for positron emission tomography (PET) imaging of prostate cancer. However, F-18-labeled compounds offer several advantages, including the potential for delayed imaging, high starting activities enabling multidose preparation, and improved spatial resolution in PET. For F-18 labeling of peptides conjugated with a suitable chelator, a fast and feasible method is the use of [Al18F]2+. In the present study, the radiofluorinations of a well-known PSMA ligand Glu-NH-CO-NH-Lys(Ahx)-HBED-CC (PSMA-HBED) via [Al18F]2+ were performed with respect to various reaction parameters, along with the biological evaluations in a cell experiment. [Al18F]PSMA-HBED was prepared by adding Na[18F]F into a vial containing 0.026 μmol peptide (in 0.05 M NaOAc buffer) and 0.03 μmol AlCl3⋅6H2O (in 0.05 M NaOAc buffer). Then, it was stirred at different temperatures from 1 to 30 min. Afterwards, purification was carried out by solid phase extraction. Biological evaluations were performed in PSMA-positive cell lines LNCaP C4-2, along with a negative control using PC-3 cell lines. The best labeling results (81 ± 0.5 %, n = 4) were observed with 0.026 μmol peptide (30 °C, 5 min). For preclinical experiments, the production of [Al18F]PSMA-HBED at 35 °C including purification by solid phase extraction (SPE) succeeded within 45 min, resulting in a radiochemical yield of 49 ± 1.2 % (decay-corrected, n = 6, radiochemical purity ≥98 %) at EOS. The labeled peptide revealed serum stability for 4 h as well as a promising binding coefficient (K
 D) value of 10.3 ± 2.2 nM in cell experiments with PSMA-positive LNCaP C4-2 cells. An efficient and one-pot method for the radiosynthesis of [Al18F]PSMA-HBED was developed (0.26 μmol of precursor at 35 °C). In cell culture studies, the K
 D suggests [Al18F]PSMA-HBED as a potential PSMA ligand for future investigations in vivo and clinical applications afterwards.

Radiofluorination of PSMA-HBED via Al(18)F(2+) Chelation and Biological Evaluations In Vitro.

In peptide receptor radionuclide therapy with 90Y-labeled DOTATATE, the kidney absorbed dose limits the maximum amount of total activity that can be safely administered in many patients. A higher tumor-to-kidney absorbed dose ratio might be achieved by optimizing the amount of injected peptide and activity, as recent studies have shown different degrees of receptor saturation for normal tissue and tumor. The aim of this work was to develop and implement a modeling method for treatment planning to determine the optimal combination of peptide amount and pertaining therapeutic activity for each patient. Methods: A whole-body physiologically based pharmacokinetic (PBPK) model was developed. General physiologic parameters were taken from the literature. Individual model parameters were fitted to a series (n = 12) of planar γ-camera and serum measurements (111In-DOTATATE) of patients with meningioma or neuroendocrine tumors (NETs). Using the PBPK model and the individually estimated parameters, we determined the tumor, liver, spleen, and red marrow biologically effective doses (BEDs) for a maximal kidney BED (20 Gy2.5) for different peptide amounts and activities. The optimal combination of peptide amount and activity for maximal tumor BED, considering the additional constraint of a red marrow BED less than 1 Gy15, was individually quantified. Results: The PBPK model describes the biokinetic data well considering the criteria of visual inspection, the coefficients of determination, the relative standard errors (

https://jnm.snmjournals.org/content/jnumed/57/4/503.full.pdf

Optimized Peptide Amount and Activity for ⁹⁰Y-Labeled DOTATATE Therapy.

Radiosynthesis of a new PSMA targeting ligand ([18F]FPy-DUPA-Pep).

Up to now, many radiolabeled ligands targeting prostate-specific membrane antigen (PSMA) have been synthesized. To carry out radiofluorinations, there have been several approaches mainly involving two steps of radiosynthesis. However, in case of labelings with high activities, one radiosynthetic step (‘one pot synthesis’) is highly desirable. As an alternative, radiofluorinations of peptides coupled to the NOTA complex via Al18F appear to be very promising, both in terms of feasible labelling procedure and stability in vivo. Therefore, in the present study, we synthesized a new PSMA-ligand, that is, NOTA-DUPA-Pep, labeled with Al18F and examined the reaction kinetics in dependence on temperature, time, concentration of precursor, and AlCl3 solution. Highest radiochemical yields of 83 ± 1.1% were obtained at 105 °C after 15 min of reaction time. At the end of synthesis, [Al18F]NOTA-DUPA-Pep was prepared with a radiochemical purity of ≥98% with an overall yield of 79 ± 0.7% (n = 3) (decay uncorrected) within 55 min. Copyright © 2012 John Wiley & Sons, Ltd.

Noeen Malik

Papers

Biodistribution and delivery efficiency of unmodified tumor-derived exosomes.

Radiofluorination of PSMA-HBED via Al(18)F(2+) Chelation and Biological Evaluations In Vitro.

Optimized Peptide Amount and Activity for ⁹⁰Y-Labeled DOTATATE Therapy.

Radiosynthesis of a new PSMA targeting ligand ([18F]FPy-DUPA-Pep).

One pot radiofluorination of a new potential PSMA ligand [Al18F]NOTA-DUPA-Pep