Preladenant

Immunotherapy is a promising cancer treatment strategy. In contrast, programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitors are associated with low response rates and are only useful in a small group of cancer patients. A combination of treatments may be effective for overcoming this clinical issue. Preladenant is an adenosine (ADO) receptor inhibitor that can block the ADO pathway and improve the tumor microenvironment (TME), thereby enhancing the immunotherapeutic effect of PD-1 inhibitors. However, its poor water solubility and low targeting limit its clinical applications. We designed a PEG-modified thermosensitive-liposome (pTSL) loaded with ADO small molecule inhibitor preladenant (P-pTSL) to overcome these problems and enhance the effect of PD-1 inhibitor on breast cancer immunotherapy. The prepared P-pTSL was round and uniformly distributed with a particle size of (138.9 ± 1.22) nm, PDI: 0.134 ± 0.031, and zeta potential (-10.1 ± 1.63) mV; preladenant was released slowly at 37 °C but released fast at 42 °C from P-pTSL, which was 76.52 ± 0.44%. P-pTSL has good long-term and serum stability and excellent tumor-targeting ability in mice. Moreover, the combination with PD-1 inhibitor significantly enhanced the anti-tumor effect, and the improvement of related factors in serum and lymph was more obvious under the condition of 42 °C thermotherapy in vitro.

The G protein‐coupled adenosine A2A receptor (A2AAR) is an important new (potential) drug target in immuno‐oncology, and for neurodegenerative diseases. Preladenant and its derivatives belong to the most potent A2AAR antagonists displaying exceptional selectivity. While crystal structures of the human A2AAR have been solved, mostly using the A2A‐StaR2 protein that bears 9 point mutations, co‐crystallization with Preladenant derivatives has so far been elusive. We developed a new A2AAR construct harboring a single point mutation (S913.39K) which renders it extremely thermostable. This allowed the co‐crystallization of two novel Preladenant derivatives, the polyethylene glycol‐conjugated (PEGylated) PSB‐2113, and the fluorophore‐labeled PSB‐2115. The obtained crystal structures (2.25 Å and 2.6 Å resolution) provide explanations for the high potency and selectivity of Preladenant derivatives. They represent the first crystal structures of a GPCR in complex with PEG‐ and fluorophore‐conjugated ligands. The applied strategy is predicted to be applicable to further class A GPCRs.