MMP inhibitor(Paratek Pharmaceuticals)

Treatment of cancer patients with anthracyclines is known to cause dose‐dependent cardiotoxicity through several mechanisms including enhanced oxidative stress, ultimately resulting in defective excitation–contraction coupling. Loss of junctophilin‐2 (JPH‐2), which tethers transverse tubules (T‐tubules) to the sarcoplasmic reticulum, is a feature of doxorubicin‐induced cardiotoxicity, yet the protease involved in unclear. As activation of matrix metalloproteinase‐2 (MMP‐2) is known to contribute to doxorubicin‐induced cardiotoxicity, we investigated here the role of MMP‐2 in JPH‐2 proteolysis and defective calcium transients in it.

C57BL/6J mice were treated with doxorubicin for 4 weeks with or without the MMP inhibitor (doxycycline), MMP‐2 preferring inhibitor (ONO‐4817) or vehicle, and cardiac function was assessed using echocardiography. JPH‐2 levels in ventricular extracts were measured. Calcium transients and JPH‐2 levels were measured in neonatal rat ventricular cardiomyocytes treated with doxorubicin and ONO‐4817.

Both MMP inhibitors attenuated doxorubicin‐induced cardiac systolic and diastolic dysfunction. Doxorubicin treatment resulted in JPH‐2 cleavage in mouse hearts as evidenced by the appearance of lower molecular weight products of 63 and 25 kDa, which was prevented by MMP inhibitors. Loss of JPH‐2 and impaired calcium transients were observed in neonatal rat ventricular cardiomyocytes treated with doxorubicin, while ONO‐4817 attenuated these changes. In silico analysis predicted cleavage sites between JPH‐2 MORN repeats and within its unstructured region.

These results reveal that JPH‐2 proteolysis is a consequence of MMP‐2 activation and highlight the beneficial prophylactic action of two orally available MMP inhibitors in preventing doxorubicin‐induced cardiotoxicity.

Glioblastoma presents a significant treatment challenge due to the blood-brain barrier (BBB) hindering drug delivery, and the overexpression of matrix metalloproteinases (MMPs), which promotes tumor invasiveness. This study introduces a novel nanostructured lipid carrier (NLC) system designed for the delivery of batimastat, an MMP inhibitor, across the BBB and into the glioblastoma microenvironment. The NLCs were functionalized with epidermal growth factor (EGF) and a transferrin receptor-targeting construct to enhance BBB penetration and entrapment within the tumor microenvironment. NLCs were prepared by ultrasonicator-assisted hot homogenization, followed by surface functionalization with EGF and the construct though carbodiimide chemistry. The construct was successfully conjugated with an efficiency of 81%. Two functionalized NLC formulations, fMbat and fNbat, differing in the surfactant amount, were characterized. fMbat had a size of 302 nm, a polydispersity index (PDI) of 0.298, a ζ-potential (ZP) of -27.1 mV and an 85% functionalization efficiency (%FE), whereas fNbat measured 285 nm, with a PDI of 0.249, a ZP of -28.6 mV and a %FE of 92%. Both formulations achieved a drug loading of 0.42 μg/mg. In vitro assays showed that fNbat was cytotoxic and failed to cross the BBB, while fMbat showed cytocompatibility at concentrations 10 times higher than the drug's IC50. Additionally, fMbat inhibited MMP-2 activity between 11 and 62% across different cell lines and achieved a three-fold increase in BBB penetration upon functionalization. Our results suggest that the fMbat formulation has potential for enhancing GB treatment by overcoming current drug delivery limitations and may be combined with other therapeutic strategies for improved outcomes.