Targeting dihydroorotate dehydrogenase (hDHODH) beyond the barrier: discovery of MEDS700 as blood-brain barrier permeable hDHODH inhibitor

  • Eur J Med Chem. 2026 Sep 15:314:118896. doi: 10.1016/j.ejmech.2026.118896.
Stefano Sainas  1 ,  Chiara Vigato  2 ,  Paola Circosta  3 ,  Manuela Zonfrillo  4 ,  Tiziana Servidei  5 ,  Marta Alberti  6 ,  Martina Rescigno  4 ,  Riccardo Miggiano  6 ,  Valentina Gaidano  7 ,  Nicoletta Vitale  8 ,  Alice Passoni  9 ,  Alessia Lanno  9 ,  Barbara Buccinnà  10 ,  Marco Piccinini  10 ,  Martina Lorenzati  11 ,  Serena Gentile  5 ,  Gianluca Sferrazza  12 ,  Alessandro Sgambato  13 ,  Giuseppe Saglio  14 ,  Marta Giorgis  1 ,  Donatella Boschi  1 ,  Marco L Lolli  15
Affiliations
  • 1. Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, Turin, 10125, Italy; Drug Discovery and Clinic s.r.l., Via Gioacchino Quarello 15/A, Torino, 10135, Italy.
  • 2. Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, Turin, 10125, Italy.
  • 3. Drug Discovery and Clinic s.r.l., Via Gioacchino Quarello 15/A, Torino, 10135, Italy; Department of Clinical and Biological Sciences, University of Turin, Regione Gonzole 10, Orbassano, Turin, 10043, Italy; Molecular Biotechnology Center, University of Turin, Via Nizza 52, Turin, 10126, Italy.
  • 4. Translational Pharmacology Institute of Rome (IFT), Research National Council (CNR), Via Fosso del Cavaliere 100, Rome, 00133, Italy.
  • 5. Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy.
  • 6. Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via G. Bovio 6, Novara, 28100, Italy.
  • 7. Division of Hematology and Cell Therapy, AO Ordine Mauriziano, Largo Filippo Turati, 62, Turin, 10128, Italy.
  • 8. Department of Molecular Biotechnologies and Health Science, University of Turin, Via Nizza 52, Turin, 10126, Italy.
  • 9. Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, Milan, 20156, Italy.
  • 10. Department of Oncology, University of Turin, Via Michelangelo Buonarroti 27/B, Turin, 10125, Italy.
  • 11. Department of Neuroscience Rita Levi-Montalcini, University of Torino, Via Cherasco 15, Torino, 10126, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), University of Torino, Regione Gonzole 43, Orbassano, 10043, Italy.
  • 12. Department of Biomedical Sciences, Research National Council (CNR), Piazzale Aldo Moro 7, Rome, 00185, Italy.
  • 13. Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, 00168, Italy; Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, 00168, Italy.
  • 14. Drug Discovery and Clinic s.r.l., Via Gioacchino Quarello 15/A, Torino, 10135, Italy.
  • 15. Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, Turin, 10125, Italy; Drug Discovery and Clinic s.r.l., Via Gioacchino Quarello 15/A, Torino, 10135, Italy. Electronic address: [email protected].
PMID: 42119261 DOI: 10.1016/j.ejmech.2026.118896
Abstract

Targeting Cancer metabolism, particularly de novo nucleotide biosynthesis, has emerged as a promising and innovative therapeutic strategy for both hematologic and solid malignancies, including those of the Central Nervous System (CNS). Glioblastoma Cancer stem-like cells are especially vulnerable to pyrimidine synthesis inhibition, highlighting human Dihydroorotate Dehydrogenase (hDHODH), a rate-limiting enzyme in the de novo pathway, as a potential therapeutic target. MEDS433 is a best-in-class hDHODH inhibitor, that shows efficacy in vivo after oral administration but lacks efficient penetration of the blood-brain barrier (BBB), limiting its utility against CNS tumors. Its lipophilic analogue MEDS613 showed enhanced cellular potency, but its poor metabolic stability and rapid conversion to hydroxylated metabolites precluded its future clinical development. In this study, we aimed to design a novel BBB-permeable hDHODH inhibitor, capable of effectively targeting CNS-localized hDHODH. We began by identifying the metabolic soft spots present in the propyloxy side chain of MEDS613 using this information to develop a metabolically stable analogue, MEDS700 (compound 3, as named in the manuscript), that was shown to inhibit hDHODH in the low nanomolar range (IC50hDHODH 1.5 nM). Subsequently, MEDS700 was fully profiled, including detailed analysis of its crystallographic binding mode, pan-antitumor activities in cell-based assays and in vitro cytotoxicity on Peripheral Blood Mononuclear Cells (PBMC). An in vivo pharmacokinetic experiment demonstrated that MEDS700 was able to cross the blood-brain barrier, maintaining therapeutically relevant intracerebral concentrations for up to 24 h after oral administration. Our findings establish MEDS700 as a potent, safe, metabolically stable hDHODH inhibitor, indicating it as a promising candidate for the treatment of hard-to-reach brain tumors.

Keywords
2-Hydroxypyrazolo[1,5-a]pyridine; Bioisosterism; Blood-brain barrier; Brequinar; Dihydroorotate dehydrogenase (DHODH) inhibitors; Gliomas; MEDS433; Metabolism.
Products