Cancer immunotherapy has attracted increasing attention over the last few years. Programmed cell death protein 1 (PD-1) promotes self-tolerance and inhibits immune responses by modulating the T-cell function. The interaction between PD-1 and programmed cell death ligand-1 (PD-L1) leads to immune exhaustion, protecting cancer cells from destruction. Here, we computationally designed a novel ligand named 1508 that binds to an unprecedented PD-1 cavity identified by MixMD and defined by amino acid residues Lys78 to Val97. We showed through a set of MD simulations totaling 12.5 μs that ligand 1508 establishes frequent cation−π and hydrogen bonding interactions with amino acid residues Lys78 and Arg86, respectively, and stabilizes the PD-1 C′D loop in a conformation that does not favor PD-1−PD-L1 complex formation. This study highlights the power of MixMD in exposing new cavities prone to protein−protein complex inhibition and establishes the basis for the design of new molecules that target the PD-1 C′D cavity as an alternative for exploring the modulation of the PD-1−PD-L1 complex in cancer therapy.

Integrins are transmembrane receptors that play a critical role in many biological processes which can be therapeutically modulated using integrin blockers, such as peptidomimetic ligands. This work aimed to develop new potential β1 integrin antagonists using modeled receptors based on the aligned crystallographic structures and docked with three lead compounds (BIO1211, BIO5192, and TCS2314), widely known as α4β1 antagonists. Lead-compound complex optimization was performed by keeping intact the carboxylate moiety of the ligand, adding substituents in two other regions of the molecule to increase the affinity with the target. Additionally, pharmacokinetic predictions were performed for the ten best ligands generated, with the lowest docking interaction energy obtained for α4β1 and BIO5192. Results revealed an essential salt bridge between the BIO5192 carboxylate group and the Mg2+ MIDAS ion of the integrin. We then generated more than 200 new BIO5192 derivatives, some with a greater predicted affinity to α4β1. Furthermore, the significance of retaining the pyrrolidine core of the ligand and increasing the therapeutic potential of the new compounds is emphasized. Finally, one novel molecule (1592) was identified as a potential drug candidate, with appropriate pharmacokinetic profiles, similar dynamic behavior at the integrin interaction site compared with BIO5192, and a higher predicted affinity to VLA-4.

Flavonoids are a class of natural products widely available in medicinal and dietary plants. Their pharmacological use has shown the potential to reduce the risk of different types of cancer, among other prevalent diseases. Their molecular scaffold inhibits the PD-1/PD-L1 axis, an important pathway related to the adaptive immune resistance of cancer cells already targeted for developing new cancer immunotherapy. However, despite the availability of kinetic and thermodynamic experimental data on the flavonoid–PD-1/PD-L1 interaction, there is still a lack of reliable information about their binding mode at the atomic level. Thus, we aimed to computationally predict the binding mode of flavonoid molecules with PD-1 and/or PD-L1 proteins using unbiased computational methodologies such as blind docking and supervised molecular dynamics simulation. The molecular interactions and dynamics of these predicted poses of protein-flavonoid complexes were further analyzed through multiple molecular dynamics simulations. This information, corroborated with the IC50 and KD values from available literature, was used to perform molecular matched-pair analysis to comprehensively describe the main interactions governing the inhibition of the complex PD-1/PD-L1 by the flavonoid scaffold. By analyzing the effect of substitutions in such a scaffold, we observed a clear correspondence with literature binding assays. Thus, we propose, for dimeric PD-L1, that the 7-O-glucoside forces the molecule displacement in the dimer interface. Furthermore, the 3-OH plays an essential role in stabilizing the buried binding mode by water-bridged hydrogen bonds with Asp122 and Gln66 in both extremities of the pocket. In PD-1, we suggest that flavonoids could bind through the BC loop by inducing a flip of Phe56 after a conformational change of the Asn58 glycosylation. Hence, our results introduced unprecedented information on flavonoid interaction and dynamics when complexed with PD-1 checkpoint pathway proteins and can pave the road for developing new flavonoid derivatives with selective anticancer activity.

Resumo A aplicação de lipossomas para a administração controlada de fármacos tem tido um grande impacto em muitas áreas biomédicas. Verificou-se que eles são benéficos para a estabilização de compostos terapêuticos, superação de obstáculos à absorção celular e de tecidos e melhoria da biodistribuição de compostos para locais-alvo in vivo. Essa prospecção teve como objetivo analisar as patentes que tratam da utilização de lipossomas como veículos de drug delivery. A busca foi realizada nos bancos de dados do INPI e do EPO. As patentes encontradas foram analisadas quanto a quantidade, datas de publicação, país de origem dos depositantes e dos inventores, país Revista GEINTEC

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