Exploring a mucoacting spray-dried nanoparticle-in-microparticle inhalable formulation for targeted pulmonary delivery of sorafenib in lung cancer therapy

In this study, we developed an inhalable Nano–in–Micro (NiM) system for localized delivery of Sorafenib (Sor) in non-small cell lung cancer (NSCLC) therapy. Sor was encapsulated into mucus-penetrating and folate-targeted polymeric nanoparticles (FA-PPP-NPs@Sor), produced starting from the α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA), functionalised with poly(lactic-co-glycolic acid) (PLGA), and folate-conjugated polyethylene glycol (PEG-FA) FA (DDPLGA = 3.3 mol %, DDPEG–FA ≈ 8 chains/molecule). Nanoprecipitation produced 109 nm particles, easy to redisperse, with a DL of 10 wt%, which showed a controlled release of the drug, about 8.4 wt% (pH 7.4) vs. 21.7 wt% (pH 5.5) in 24 h. A selective cytotoxicity towards A549 lung cancer cells via folate receptor-mediated internalization was found, being IC50 = 18 ± 3.2 μM, significantly lower than those found both in 16HBE cells (IC50 = 69 ± 3.1 μM and free Sor (IC50 = 17.7 ± 2.3 μM). The receptor involvement was confirmed by competitive folate blocking, which raised IC50 >100 μM. Wound healing assay performed to evaluate the ability of Sor-loaded nanoparticles to inhibit or reduce cell migration showed 27 % vs. 40 % wound closure at 48 h (NiM vs Sor). The nanoparticles were further incorporated into inhalable microparticles via spray drying (SD), using mannitol, leucine, N-acetylcysteine, and ammonium bicarbonate as functional excipients (yield 63 wt%, EE = 100 wt%, DL = 0.35 wt%). The spray dried NiMSor microparticles exhibited a MMAD and a FPF, respectively, of 2.2 μm and 76 %, suitable for deep lung delivery. Furthermore, their storage at r.t. and dissolution in water reconstitutes the nanoparticle dispersion. Rheology tests demonstrated time– and concentration– dependent mucus thinning. Overall, this study presents a promising inhalable platform for targeted lung cancer therapy, combining targeted cytotoxicity, mucus penetration, controlled release, and favourable aerosol properties.