For many years now, targeting deregulation within cancer cells’ metabolism has appeared as a promising strategy for the development of more specific and efficient cancer treatments. Recently, numerous reports highlighted the crucial role of the serine synthetic pathway, and particularly of the phosphoglycerate dehydrogenase (PHGDH), the first enzyme of the pathway, to sustain cancer progression. Yet, because of very weak potencies usually in cell-based settings, the inhibitors reported so far failed to lay ground on the potential of this approach. In this paper, we report a structure–activity relationship study of a series of α-ketothioamides that we have recently identified. Interestingly, this study led to a deeper understanding of the structure–activity relationship (SAR) in this series and to the identification of new PHGDH inhibitors. The activity of the more potent compounds was confirmed by cellular thermal shift assays and in cell-based experiments. We hope that this research will eventually provide a new entry point, based on this promising chemical scaffold, for the development of therapeutic agents targeting PHGDH.

The serine biosynthetic pathway is a key element contributing to tumor proliferation. In recent years, targeting of phosphoglycerate dehydrogenase (PHGDH), the first enzyme of this pathway, intensified and revealed to be a promising strategy to develop new anticancer drugs. Among attractive PHGDH inhibitors are the α-ketothioamides. In previous work, we have demonstrated their efficacy in the inhibition of PHGDH in vitro and in cellulo. However, the precise site of action of this series, which would help the rational design of new inhibitors, remained undefined. In the present study, the detailed mechanism-of-action of a representative α-ketothioamide inhibitor is reported using several complementary experimental techniques. Strikingly, our work led to the identification of an allosteric site on PHGDH that can be targeted for drug development. Using mass spectrometry experiments and an original α-ketothioamide diazirine-based photoaffinity probe, we identified the 523Q-533F sequence on the ACT regulatory domain of PHGDH as the binding site of α-ketothioamides. Mutagenesis experiments further documented the specificity of our compound at this allosteric site. Our results thus pave the way for the development of new anticancer drugs using a completely novel mechanism-of-action.

The adenosine A_2A receptor (A_2AR) has been identified as a therapeutic target for treating neurodegenerative diseases and cancer. In recent years, we have highlighted the 2-aminoquinazoline heterocycle as an promising scaffold for designing new A_2AR antagonists, exemplified by 6-bromo-4-(furan-2-yl)quinazolin-2-amine 1 (K_i (hA_2AR) = 20 nM). Here, we report the synthesis of new 2-aminoquinazoline derivatives with substitutions at the C6- and C7-positions, and the introduction of aminoalkyl chains containing tertiary amines at the C2-position to enhance antagonist activity and solubility properties. Compound 5m showed a high affinity for hA_2AR with a K_i value of 5 nM and demonstrated antagonist activity with an IC₅₀ of 6 µM in a cyclic AMP assay. Introducing aminopentylpiperidine and 4-[(piperidin-1-yl)methyl]aniline substituents maintained the binding affinities (9x, K_i = 21 nM; 10d, K_i = 15 nM) and functional antagonist activities (9x, IC₅₀ = 9 µM; 10d, IC₅₀ = 5 µM) of the synthesized compounds while improving solubility. This study provides insights into the future development of A_2AR antagonists for therapeutic applications.

Multiple Sclerosis (MS) is an autoimmune demyelinating and neurodegenerative disease of the central nervous system (CNS). Current management strategies suppress or modulate immune function, all with consequences and known side effects. They demonstrate a high level of success in limiting new relapses. However, the neurodegenerative process still affects both grey and white matter in the central nervous system. The sigma1 (S1R) ligand-regulated chaperone is implicated in many biological processes in various CNS-targeted diseases, acting on neural plasticity, myelination and neuroinflammation. Among the proteins involved in MS, S1R has therefore emerged as a promising new target. Standard and robust methods have been adopted to analyze the adsorption, distribution, metabolism, excretion (ADME) properties, safety pharmacology and toxicology of a previously synthetized simple benzamide-derived compound with nanomolar affinity for S1R, high selectivity, no cytotoxicity and good metabolic stability. The compound was also characterized as an agonist based on well-validated assays prior to in vivo investigations. Interestingly, we found that the oral administration of this compound resulted in an overall significant reduction in clinical progression in an MS experimental model. This effect is mediated through S1R action. Our results further suggest the potential use of this compound in the treatment of MS.

Central nervous system (CNS) disorders such as neurodegenerative diseases, multiple sclerosis, or even brain ischemia represent major therapeutic challenges with limited effective treatments. The sigma-1 receptor (S1R), a unique ligand-operated molecular chaperone enriched at mitochondria-associated membranes, has emerged as a promising drug target due to its role in neuroprotection and neuroinflammation. Building upon our previously identified S1R ligand (compound 1), we designed and synthesized six novel benzamide derivatives through pharmacomodulation to optimize affinity, selectivity, and safety profiles. Among these, compound 2 demonstrated superior S1R affinity, improved selectivity over the sigma-2 receptor (S2R), and favorable ADME properties, including enhanced permeability and markedly reduced in vitro cardiac toxicity compared to the lead compound. Functional assays confirmed the agonist activity of key derivatives, while safety evaluations revealed low cytotoxicity and minimal off-target receptor interactions. Collectively, these findings support compound 2 as a promising candidate for further preclinical development in S1R-related CNS disorders.

Lipid metabolism affects many cellular processes essential for homeostasis, and its disruption is linked to various diseases. A key enzyme in these processes, acyl-coenzyme A synthetase long-chain family member 4 (ACSL4), is a promising target for treating conditions involving ferroptosis and certain cancers. Rosiglitazone (ROSI) is a known ACSL4 inhibitor but its potent activity on peroxisome proliferator-activated receptor gamma (PPARγ), a nuclear receptor strongly involved in lipid metabolism constitutes an important limitation. This study focuses on developing novel ACSL4 inhibitors derived from ROSI, which lack PPARγ activity. Binding of the most potent compound of this series (9) relies on the prior binding of ATP. Hydrogen-Deuterium Exchange Mass Spectrometry (HDx-MS) demonstrated that ATP binding stabilizes the ACSL4 C-terminus, an effect enhanced by compound 9, which also alters important peptide sequences, including the fatty acid gate-domain. Photoaffinity Labeling (PAL) with a diazirine-based probe identified residue A329 in the fatty acid pocket. Molecular dynamics simulations and site-directed mutagenesis highlighted Q302 as critical for compound 9 binding. Thus, compound 9 (LIBX-A401) is a promising tool for studying ACSL4 in ferroptosis-related diseases and cancer, and the elucidation of its binding mode paves the way to the rational design of optimized inhibitors