Use of NSCLC cell models to identify drug combinations active on <i>LKB1</i>-mutated NSCLCs

In the context of the lack of effective therapies for <i>LKB1</i>-mutated NSCLC, this thesis aimed to identify a valuable therapeutic strategy to manage these patients and improve their prognosis. Our previous research highlighted the sensitivity of <i>LKB1</i>-mutated NSCLC to the pharmacological inhibition of ERK. However, the presence of additional mutations that activate parallel ERK pathways abolished the effect of this drug, limiting its clinical use as monotherapy. This thesis project comprises three main parts. In the first section, using high throughput screening and drug repurposing strategies, the project identified ERK inhibitor (ERKi)-Entrectinib combination as a possible effective and specific therapeutic strategy for <i>LKB1</i>-mutated cell lines. The efficacy of this combination was confirmed, in the second section, both <i>in vitro</i> with different cell viability assay and <i>in vivo</i> where a significant slowdown of <i>LKB1</i>-mutated tumor growth was highlighted. Moreover, initial <i>in vitro</i> characterisation of the mechanism of action behind this combination activity showed that it induces deregulation of p-S6, a downstream mTOR protein, specifically in <i>LKB1</i>-mutated NSCLC cell lines. However, further studies are necessary to investigate the role of Entrectinib targets. Finally, the ERKi-Entrectinib combination treatment induced activation of apoptotic programmed cell death only in <i>LKB1</i>-mutated cell lines. The third section of this work, instead, aimed at generating NSCLC 3D models, specifically Patient-Derived Xenograft (PDX)-derived Organoids (PDXO), which better mimic the 3D structure of the tumor mass and could bridge the gap between 2D cell lines and PDXs. Through the optimization and implementation of new method this thesis confirmed the technical feasibility, management and utility of PDXOs. This <i>ex vivo</i> model, indeed, fully recapitulate the characteristics of the NSCLC tumor of origin in terms of genetic fingerprinting, human lung epithelial cell composition, histological and mutational profile, and are suitable for pharmacological treatment test.