Pharmacology of Adenosine Receptors: Recent Advancements

Ectonucleotidase inhibitors: an updated patent review (2017-2023)

INTRODUCTION

The main enzymes that hydrolyzes nucleotides at the cell surface are nucleoside triphosphate diphosphohydrolases (NTPDases), ecto-nucleotide pyrophosphatases/phosphodiesterases (ENPPs), alkaline phosphatases (APs) and ecto-5'- nucleotidase (e5'NT, CD73) and by regulating the concentration of nucleotides at the cell surface, these enzymes have the potential to affect various conditions such as fibrosis, cancer metastasis, pruritus, inflammation, and autoimmune diseases. Thus, they represent a prospective therapeutic target.

AREA COVERED

A number of molecules, including nucleoside/nucleotide and non-nucleoside analogues, and bicyclic compounds, have shown strong potential as ectonucleotidase inhibitors. This review covers the chemistry and clinical uses of ectonucleotidase inhibitors patented between 2017 and 2023.

EXPERT OPINION

By binding to their specific P1 and P2 receptors at the cell surface, nucleosides and nucleotides regulate a number of pathophysiological events such as inflammation, fibrosis, cancer, and autoimmune diseases. Interestingly, these nucleotides can be hydrolyzed to nucleosides by several cell surface enzymes called ectonucleotidases. The development of small molecules that modulate ectonucleotidase activity is, therefore, of therapeutic value. This review provides valuable insights into recent advancements, including combination therapy and enhanced selectivity, which are poised to shape the future of ectonucleotidase inhibition through a comprehensive analysis of patents.

Development of Preladenant-Based Radiotracers for Imaging A2AR in Tumors

Activation of the adenosine 2A receptor (A2AR) can lead to tumor immunosuppression, which results in poor prognosis of immunotherapy. The aim of this study was to design novel 18F-labeled probes ([18F]F-PFP2 and [18F]F-PFP4) to visualize A2AR in the tumor. The uptake of radioprobes in A2AR-negative 4T1 breast tumor was lower than that of A2AR-positive B16F10 melanoma at 1 h p.i. (1.22 ± 0.36% ID/g vs 2.80 ± 0.72% ID/g), 2 h p.i. (1.09 ± 0.20% ID/g vs 2.93 ± 0.76% ID/g) and 3 h p.i. (0.89 ± 0.27% ID/g vs 2.73 ± 0.58% ID/g), respectively. B16F10 lung metastasis models were employed to expand the application scenarios, observing significantly higher uptake of [18F]F-PFP2 in metastatic lesions compared to normal lung tissue (5.55 ± 2.18% ID/g vs 1.89 ± 0.65% ID/g, tumor/lung ratio ∼3). It is given that [18F]F-PFP2 might lay the foundation for establishing an A2AR-targeted imaging evaluation system for tumors, which will provide more precise guidance for personalized treatment.