Novel Bifunctional Conjugates Targeting PD-L1/PARP7 as Dual Immunotherapy for Potential Cancer Treatment.

Bifunctional conjugates targeting PD-L1/PARP7 were designed, synthesized, and evaluated for the first time. Compounds B3 and C6 showed potent activity against PD-1/PD-L1 interaction (IC50 = 0.426 and 0.342 µM, respectively) and PARP7 (IC50 = 2.50 and 7.05 nM, respectively). They also displayed excellent binding affinity with hPD-L1, approximately 100-200-fold better than that of hPD-1. Both compounds restored T-cell function, leading to the increase of IFN-γ secretion. In the coculture assay, B3 and C6 enhanced the killing activity of MDA-MB-231 cells by Jurkat T cells in a concentration-dependent manner. Furthermore, B3 and C6 displayed significant in vivo antitumor efficacy in a melanoma B16-F10 tumor mouse model, more than 5.3-fold better than BMS-1 (a PD-L1 inhibitor) and RBN-2397 (a PARP7i clinical candidate) at the dose of 25 mg/kg, without observable side effects. These results provide valuable insight and understanding for developing bifunctional conjugates for potential anticancer therapy.

Design, Synthesis, and Structure-Activity Relationship of Novel Pyridazinone-Based PARP7/HDACs Dual Inhibitors for Elucidating the Relationship between Antitumor Immunity and HDACs Inhibition.

Histone deacetylases (HDACs) inhibitors such as vorinostat (SAHA) has been used to treat hematologic malignancies (rather than solid tumors) and have been found to suppress the JAK/STAT, a critical signal pathway for antitumor immunity, while PARP7 inhibitor RBN-2397 could activate the type I interferons (IFN-I) pathway, facilitating downstream effects such as STAT1 phosphorylation and immune activation. To elucidate whether simultaneous inhibition of these two targets could interfere with these two signal pathways, a series of pyridazinone-based PARP7/HDACs dual inhibitors have been designed, synthesized, and evaluated in vitro and in vivo experiments. Compound 9l was identified as a potent and balanced dual inhibitor for the first time, exhibiting excellent antitumor capabilities both in vitro and in vivo. This suggests that 9l can be used as a valuable tool molecule for investigating the relationship between anticancer immunity and HDAC inhibition.

Recent progress in discovery of novel AAK1 inhibitors: from pain therapy to potential anti-viral agents.

Adaptor associated kinase 1 (AAK1), a member of the Ark1/Prk1 family of Ser/Thr kinases, is a specific key kinase regulating Thr156 phosphorylation at the µ2 subunit of the adapter complex-2 (AP-2) protein. Due to their important biological functions, AAK1 systems have been validated in clinics for neuropathic pain therapy, and are being explored as potential therapeutic targets for diseases caused by various viruses such as Hepatitis C (HCV), Dengue, Ebola, and COVID-19 viruses and for amyotrophic lateral sclerosis (ALS). Centreing on the advances of drug discovery programs in this field up to 2023, AAK1 inhibitors are discussed from the aspects of the structure-based rational molecular design, pharmacology, toxicology and synthetic routes for the compounds of interest in this review. The aim is to provide the medicinal chemistry community with up-to-date information and to accelerate the drug discovery programs in the field of AAK1 small molecule inhibitors.

Design, Synthesis and Biological Evaluation of Histone Deacetylase Inhibitors Based on Pyrrolo[2,3-d]pyrimidine and Pyrrolo[2,3-b]pyridine Scaffolds.

Histone deacetylases (HDACs) are validated targets for the development of anticancer drugs in epigenetics. We have designed and synthesized a series of novel HDAC inhibitors based on pyrrolo[2,3-d]pyrimidine and pyrrolo[2,3-b]pyridine scaffolds. Compound B3 {(E)-3-(4-(((1-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)piperidin-4-yl)amino)methyl)phenyl)-N-hydroxyacrylamide} exhibits potent inhibitory activity against HDACs 1, 2, 3, 6, and 8 with IC50 values of 5.2, 6.0, 8.8, 4.4, and 173.0 nM, respectively. It exhibited potent antiproliferative effects against three tumour cell lines (IC50 values of 0.13, 0.37, and 1.11 µM, against MV-4-11, K562, and WSU-DLCL-2 cells, respectively) with two- to sixfold improvement relative to suberoylanilide hydroxamic acid (SAHA). Mechanistic studies on WSU-DLCL-2 cells revealed that B3 exhibits anticancer effects through the induction of G0 /G1 -phase arrest and promotion of apoptosis. The results of this study warrant further investigation of this compound series for the treatment of hematological malignancy.

Design, synthesis and biological evaluation of novel histone deacetylase (HDAC) inhibitors derived from ß-elemene scaffold.

ß-Elemene is the major active ingredient of TCM anticancer drug elemene extracts. To further improve its antitumor activity and poor solubility, a polar HDACi pharmacophore was incorporated its scaffold. Systematic SAR studies led to the discovery of compounds 27f and 39f, which exhibited potent inhibitory activity against HDACs (HDAC1: IC50 = 22 and 9 nM; HDAC6: 8 and 14 nM, respectively). In cellular levels, 27f and 39f significantly inhibited cell proliferation of five tumour cell lines (IC50: 0.79 - 4.42 µM). Preliminary mechanistic studies indicated that 27f and 39f efficiently induced cell apoptosis. Unexpectedly, compound 39f could also stimulate cell cycle arrest in G1 phase. Further in vivo study in WSU-DLCL-2 xenografted mouse model validated the antitumor activities of 27f, without significant toxicity. The results suggest the therapeutic potential of these HDACs inhibitors in lymphoma and provide valuable insight and understanding for further structural optimisation around ß-elemene scaffold.

Recent Progress in Fragmentation of Katritzky Salts Enabling Formation of C-C, C-B, and C-S Bonds.

Since their discovery in 1970s, Katritzky salts have emerged as one of the most important classes of building blocks for use in organic synthesis and drug discovery. These bulky pyridinium salts derived from alkylamine can readily generate alkyl radical and undergo a variety of organic transformation reactions such as alkylation, arylation, alkenylation, alkynylation, carbonylation, sulfonylation, and borylation. Through these transformations, complexed molecules bearing new C-C, C-B, or C-S bonds can be constructed in easy ways and in simple steps. This review aims to summarize recent advances in these versatile building blocks in well-classified categories. Representative examples and their reaction mechanisms are discussed. The hope is to provide the scientific community with convenient access to collective information and accelerate further research.

Recent Advances in Synergistic Antitumor Effects Exploited from the Inhibition of Ataxia Telangiectasia and RAD3-Related Protein Kinase (ATR).

As one of the key phosphatidylinositol 3-kinase-related kinases (PIKKs) family members, ataxia telangiectasia and RAD3-related protein kinase (ATR) is crucial in maintaining mammalian cell genomic integrity in DNA damage response (DDR) and repair pathways. Dysregulation of ATR has been found across different cancer types. In recent years, the inhibition of ATR has been proven to be effective in cancer therapy in preclinical and clinical studies. Importantly, tumor-specific alterations such as ATM loss and Cyclin E1 (CCNE1) amplification are more sensitive to ATR inhibition and are being exploited in synthetic lethality (SL) strategy. Besides SL, synergistic anticancer effects involving ATRi have been reported in an increasing number in recent years. This review focuses on the recent advances in different forms of synergistic antitumor effects, summarizes the pharmacological benefits and ongoing clinical trials behind the biological mechanism, and provides perspectives for future challenges and opportunities. The hope is to draw awareness to the community that targeting ATR should have great potential in developing effective anticancer medicines.

Discovery of small-molecule ATR inhibitors for potential cancer treatment: a patent review from 2014 to present.

INTRODUCTION: Ataxia telangiectasia and RAD3-related kinase (ATR) is one of the key phosphatidylinositol 3-kinase-related kinase family members important for DNA damage response and repair pathways. Targeting ATR kinase for potential cancer therapy has attracted a great deal of attention to both pharmaceutical industries and academic community. AREA COVERED: This article surveys the patents published since 2014 aiming to analyze the structural features of scaffolds and the patent space. It also discusses the recent clinical developments and provides perspectives on the challenges and the future directions. EXPERT OPINION: ATR kinase appears to be a viable drug target for anticancer therapy. Similar to DNA-PK inhibitors, the clinical investigation of an ATRi employs both monotherapy and combination strategy. In the combination strategy, an ATRi is typically combined with a radiation or a targeted drug such as chemotherapy agent poly (ADP-ribose) polymerase (PARP) inhibitor, etc. Diverse structures comprising different scaffolds from mono-heteroaryl to bicyclic heteroaryl to tricyclic heteroaryl to macrocycle are capable of achieving good ATR inhibitory activity and good ATR selectivity over other closely related enzymes. There are eight ATR inhibitors currently being evaluated in clinics, with the hope to get approval in the near future.

An updated patent review of protein arginine N-methyltransferase inhibitors (2019-2022).

Protein arginine methyltransferases (PRMTs), enzymes catalyzing the methylation of target proteins, play an essential role in maintaining functional homeostasis in normal physiology. Aberrant expressions and enhanced enzymatic activities of PRMTs have been closely associated with pathological states such as cancer, inflammatory, immune, metabolic, and neurodegenerative diseases. Therefore, the development of inhibitors targeting PRMTs has attracted a great deal of attention in both pharmaceutical industries and academic community. This review focuses on the small-molecule inhibitors targeting PRMTs in cancer therapy in the patents published since 2019. The recent clinical development is also discussed here. In recent years, the discovery of small-molecule PRMT inhibitors, especially PRMT5 inhibitors has become a rapidly expanding research area for cancer therapy. Although a number of potent PRMT inhibitors with different chemical scaffolds have been developed and nine of them have entered into clinical trials, their scaffolds are relatively less diverse. Sub-type selectivity should be considered in drug discovery as nonselective inhibition of PRMTs may cause undesirable pharmacological effects. Hence, the development of new effective inhibitors with isoform-specific and tumor-biased distributions remains an important area for further studies.