Targeted nanoliposomes of oncogenic protein degraders: Significant inhibition of tumor in lung-cancer bearing mice

With 60 % of non-small cell lung cancer (NSCLC) expressing epidermal growth factor receptor (EGFR), it has been explored as an important therapeutic target for lung tumors. However, even the well-established EGFR inhibitors tend to promptly develop resistance over time. Moreover, strategies that could impede resistance development and be advantageous for both EGFR-Tyrosine kinase inhibitor (TKI)-sensitive and mutant NSCLC patients are constrained. Based on the critical relationship between EGFR, c-MYC, and Kirsten rat sarcoma virus (K-Ras), simultaneous degradation of EGFR and Bromodomain-containing protein 4 (BRD4) using "Proteolysis Targeting Chimeras (PROTACs)" could be a promising approach. PROTACs are emerging class of oncoprotein degraders but very challanging to deliver in vivo. Compared to individual IC50s, strong synergism was observed at 1:1 ratio of BPRO and EPRO in NSCLC cell lines with diverse mutation. Significant inhibition of cell growth with higher cellular apoptosis was observed in 2D and 3D-based cell assays in nanomolar concentrations. EGFR activation assay revealed 47.60 % EGFR non-expressing cells confirming EGFR-degrading potential of EPRO. A lung cancer specific nanoliposomal formulation of EGFR and BRD4-degrading PROTACs (EPRO and BPRO) was prepared and characetrized. Successful encapsulation of the two highly lipophilic molecules was achieved in EGFR-targeting nanoliposomal carriers (T-BEPRO) using a modified hydration technique. T-BEPRO revealed a particle size of 109.22 ± 0.266 nm with enhanced cellular uptake and activity. Remarkably, parenterally delivered T-BEPRO in tumor-bearing mice showed a substantially higher % tumor growth inhibition (TGI) of 77.6 % with long-lasting tumor inhibitory potential as opposed to individual drugs.