Targeting Pf CLK3 with Covalent Inhibitors: A Novel Strategy for Malaria Treatment

J Med Chem. 2024 Nov 14;67(21):18895-18910. doi: 10.1021/acs.jmedchem.4c01300. Epub 2024 Oct 23.

Abstract

Malaria still causes over 600,000 deaths annually, with rising resistance to frontline drugs by Plasmodium falciparum increasing this number each year. New medicines with novel mechanisms of action are, therefore, urgently needed. In this work, we solved the cocrystal structure of the essential malarial kinase PfCLK3 with the reversible inhibitor TCMDC-135051 (1), enabling the design of covalent inhibitors targeting a unique cysteine residue (Cys368) poorly conserved in the human kinome. Chloroacetamide 4 shows nanomolar potency and covalent inhibition in both recombinant protein and P. falciparum assays. Efficacy in parasites persisted after a 6 h washout, indicating an extended duration of action. Additionally, 4 showed improved kinase selectivity and a high selectivity index against HepG2 cells, with a low propensity for resistance (log MIR > 8.1). To our knowledge, compound 4 is the first covalent inhibitor of a malarial kinase, offering promising potential as a lead for a single-dose malaria cure.

MeSH terms

  • Antimalarials* / chemical synthesis
  • Antimalarials* / chemistry
  • Antimalarials* / pharmacology
  • Crystallography, X-Ray
  • Hep G2 Cells
  • Humans
  • Malaria, Falciparum / drug therapy
  • Malaria, Falciparum / parasitology
  • Models, Molecular
  • Plasmodium falciparum* / drug effects
  • Plasmodium falciparum* / enzymology
  • Protein Kinase Inhibitors* / chemistry
  • Protein Kinase Inhibitors* / pharmacology
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / metabolism
  • Protozoan Proteins / antagonists & inhibitors
  • Protozoan Proteins / metabolism
  • Structure-Activity Relationship

Substances

  • Antimalarials
  • Protein Kinase Inhibitors
  • Protozoan Proteins
  • Protein Serine-Threonine Kinases