Biological activity In vitro, absorption, BBB penetration and toxicity of nanoformulation of BT44, a RET agonist with disease-modifying potential for the treatment of neurodegeneration

Abstract

BT44 is a novel, second generation glial cell line-derived neurotropic factor (GDNF) mimetic, with improved biological activity and a lead compound for the treatment of neurodegenerative disorders. Like many other small molecules, it suffers from intrinsic poor aqueous solubility, posing significant hurdles at various levels for its preclinical development and clinical translation. Herein, we report a novel poly(2-oxazoline)s (POx) based BT44 micellar nanoformulation with ultra-high drug loading capacity of 47 wt.%. The BT44 nanoformulations were comprehensively characterized by 1H-NMR spectroscopy, differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), dynamic light scattering (DLS) and cryo-transmission/scanning electron microscopy (cryo-TEM/SEM). The DSC, XRD and redispersion studies collectively confirmed that the BT44 formulation can be stored as a lyophilized powder and can be redispersed when needed. The DLS further suggested that the redispersed formulation is suitable for parenteral administration (Dh ≈ 70nm). The cryo-TEM analysis revealed the presences of worm like structures. The BT44 formulation retains biological activity in immortalized cells and in cultured dopamine neurons. The micellar formulation of BT44 exhibited improved absorption and blood-brain barrier (BBB) penetration and produced no acute toxic effects in mice. In conclusion, herein, we have developed an ultra-high BT44 loaded aqueous injectable nanoformulation, which can be used to pave way for its preclinical and clinical development for the management of neurodegenerative disorders.

Development of Poly(2-oxazoline)s and poly(2-oxazine)s based formulation library and estimation of polymer/drug compatibility.

“…Recently, the polymer A-pPentOx-A was reported to have ultrahigh LC of 47 wt.% for new investigational molecule i.e. BT-44 [44]. The targeted block length for each block in triblock copolymer is A35-B20-A35.…”

“…The targeted block length for each block in triblock copolymer is A35-B20-A35. For synthesis and characterization of four triblock copolymers, the readers are referred to previous reports [30,34,44]. These four polymers represent two pairs of structural isomers.…”

“…Compared to the other triblock copolymers used in this study, A-pPentOx-A has been been much less explored for formulation development. Recently, an ultra-high drug loaded A-pPentOx-A/BT-44 formulations (BT-44 solubility ≈ 9 g/L at 10 g/L polymer feed) [44] was reported. At all the tested ratios, the solubility of BT-44 was decreased by 90% by day 30.…”