Multicomponent reactions (MCRs) have emerged as a powerful strategy in synthetic organic chemistry due to their widespread applications in drug discovery and development. MCRs are flexible transformations in which three or more substrates react to form structurally complex products with high atomic efficiency. They are being increasingly appreciated as a highly exploratory and evolutionary tool by the medicinal chemistry community, opening the door to more sustainable, cost-effective and rapid synthesis of biologically active molecules. In recent years, MCR-based synthetic strategies have found extensive application in the field of drug discovery, and several anticancer drugs have been synthesized through MCRs. In this review, we present an overview of representative and recent literature examples documenting different approaches and applications of MCRs in the development of new anticancer drugs.

The four receptors that signal for adenosine, A₁, A_2A, A_2B and A₃ ARs, belong to the superfamily of G protein-coupled receptors (GPCRs). They mediate a number of (patho)physiological functions and have attracted the interest of the biopharmaceutical sector for decades as potential drug targets. The many crystal structures of the A_2A, and lately the A₁ ARs, allow for the use of advanced computational, structure-based ligand design methodologies. Over the last decade, we have assessed the efficient synthesis of novel ligands specifically addressed to each of the four ARs. We herein review and update the results of this program with particular focus on molecular dynamics (MD) and free energy perturbation (FEP) protocols. The first in silico mutagenesis on the A₁AR here reported allows understanding the specificity and high affinity of the xanthine-antagonist 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX). On the A_2AAR, we demonstrate how FEP simulations can distinguish the conformational selectivity of a recent series of partial agonists. These novel results are complemented with the revision of the first series of enantiospecific antagonists on the A_2BAR, and the use of FEP as a tool for bioisosteric design on the A₃AR.

Background: Adenosine is a metabolite that suppresses antitumor immune response of T and NK cells via extracellular binding to the two subtypes of adenosine-2 receptors, A₂ARs. While blockade of the A_2AARs subtype effectively rescues lymphocyte activity, with four A_2AAR antagonists currently in anticancer clinical trials, less is known for the therapeutic potential of the other A_2BAR blockade within cancer immunotherapy. Recent studies suggest the formation of A_2AAR/A_2BAR dimers in tissues that coexpress the two receptor subtypes, where the A_2BAR plays a dominant role, suggesting it as a promising target for cancer immunotherapy. Methods: We report the synthesis and functional evaluation of five potent A_2BAR antagonists and a dual A_2AAR/A_2BAR antagonist. The compounds were designed using previous pharmacological data assisted by modeling studies. Synthesis was developed using multicomponent approaches. Flow cytometry was used to evaluate the phenotype of T and NK cells on A_2BAR antagonist treatment. Functional activity of T and NK cells was tested in patient-derived tumor spheroid models. Results: We provide data for six novel small molecules: five A_2BAR selective antagonists and a dual A_2AAR/A_2BAR antagonist. The growth of patient-derived breast cancer spheroids is prevented when treated with A_2BAR antagonists. To elucidate if this depends on increased lymphocyte activity, immune cells proliferation, and cytokine production, lymphocyte infiltration was evaluated and compared with the potent A_2AAR antagonist AZD-4635. We find that A_2BAR antagonists rescue T and NK cell proliferation, IFNγ and perforin production, and increase tumor infiltrating lymphocytes infiltration into tumor spheroids without altering the expression of adhesion molecules. Conclusions: Our results demonstrate that A_2BAR is a promising target in immunotherapy, identifying ISAM-R56A as the most potent candidate for A_2BAR blockade. Inhibition of A_2BAR signaling restores T cell function and proliferation. Furthermore, A_2BAR and dual A_2AAR/A_2BAR antagonists showed similar or better results than A_2AAR antagonist AZD-4635 reinforcing the idea of dominant role of the A_2BAR in the regulation of the immune system.