Modified versions of these tetracyclines were developed for applications directed toward the specific inhibition of calpains

SUMMARY: Calpains are intracellular proteases which play a key role in cell death. The deregulation of their bio-modulating activities has been implicated in a variety of pathological conditions. Using a drug repositioning strategy, two tetracycline- derivatives, chlortetracycline and demeclocycline, have demonstrated an ability to protect mouse neurons against glutamate toxicity and cerebral ischemia through inhibition of calpains. Furthermore, modified versions of these tetracyclines were developed for applications directed toward the specific inhibition of calpains.

APPLICATIONS: Provide a new therapeutic avenue to treat disorders cause by calpain-mediated protein degradation (e.g. strokes, neurological disorders and injuries, inflammatory and infectious diseases, cancer, etc.). Develop modified tetracyclines to modulate their pharmacological properties, adapt these drugs to the treatment of a particular disease and attain selective calpain inhibition.

CONCEPT: Calpains are validated drug targets for a large number of human pathologies; however novel approaches to treat these disorders and reduce cell death effectively are needed since current options are limited. An important trend in drug development consists in finding unexploited potential in existing drugs. Such an approach allowed the identification and validation of chlortetracycline (CTC) and demeclocycline (DMC) as potent calpain inhibitors and neuroprotective compounds. The effective protection of cerebral neurons in an in vitro model of glutamate-mediated excitoxicity and in a mouse model of focal cerebral ischemia (brain stroke) by these two tetracyclines was associated with calpains inhibition. Furthermore, derivatives which retain the antioxidant/antiglycation activities of tetracyclines but lack their antibiotic and matrix metalloproteinases (MMP) inhibitory activities were developed. These derivatives are aimed at novel calpain inhibitory applications as they may be used at higher doses and for longer period of time without unessential or unwanted consequences (e.g. emergence of resistant microorganisms).

FEATURES AND BENEFITS: Powerful drug repositioning strategy - The drug repositioning of tetracyclines as calpain inhibitors offers the advantages of low risk and high reward. Indeed, these compounds which are among the most extensively used antimicrobials, have well-documented pharmacokinetic profiles (ADMET). Furthermore, tetracyclines are excellent candidates for further optimization through strategies such as our proprietary "Drug Evolution at Hot Spot" (NRC no. 11374). Currently, over thirty-five tetracycline-derivatives are ready to be screened against diseases in which calpains were validated as targets. Validated therapeutic effectiveness - The therapeutic effectiveness of CTC and DMC against brain stroke was confirmed in a mouse model (see Figure, arrows indicate ischemic infarction - white-colored region on the brain slice). The ability of these tetracyclines to cross the blood- brain barrier and to effectively protect neurons against cell death make these compounds suitable for treating brain stroke and other neurological disorders. Non-toxicity and potential synergy - Even at high concentrations, CTC and DMC demonstrated no overt toxicity while effectively protecting primary neurons culture and mice against glutamate-induced neuronal death. Minocycline, a tetracycline known to protect neurons through caspase inhibition may act synergistically with CTC and DMC since calpains activation acts upstream of the caspase cascade in the cell death pathway.

Tetracyclines and their use as calpain inhibitors (NRC no. 11570). United States, Application number 60/547,780 , Filed 2004-02- 27 Patent Cooperation Treaty, Application number PCT/CA05/000279 , Filed 2005-02-25