Date of Award

2026

Document Type

Dissertation

Degree Name

Pharmaceutical Sciences (Ph.D.)

Department

Pharmaceutical Sciences

First Advisor

Ketan Patel

Second Advisor

Zhe-Sheng Chen

Third Advisor

Sandra Reznik

Abstract

Non-small cell lung cancer (NSCLC) accounts for the majority of lung cancer cases and is frequently driven by dysregulation of oncogenic pathways involving epidermal growth factor receptor (EGFR), c-MYC, and KRAS. The emergence of acquired resistance to targeted therapies remains a major clinical challenge, necessitating the development of innovative treatment strategies. Proteolysis Targeting Chimeras (PROTACs) represent a novel therapeutic modality that induces selective degradation of disease-driving proteins via the ubiquitin–proteasome system. In this research, a dual-targeting strategy was employed to achieve simultaneous degradation of EGFR and bromodomain-containing protein 4 (BRD4), with the objective of overcoming resistance mechanisms and enhancing therapeutic efficacy in NSCLC. The specific aims were to: (i) evaluate the anticancer activity of BRD4-targeting PROTAC (BPRO), EGFR-targeting PROTAC (EPRO), and their combination (BE-PRO) in two-dimensional (2D) and three-dimensional (3D) NSCLC models; (ii) develop and characterize a BE-PRO-loaded in situ depot formulation (BERD) using a Design of Experiment (DoE) approach; and (iii) determine the in vivo anticancer efficacy of BERD in an NSCLC xenograft model. BE-PRO exhibited potent and synergistic anticancer activity in both EGFR TKI–sensitive (HCC4006) and gefitinib-resistant (HCC4006/GR) cell lines, significantly inhibiting migration, clonogenic growth, and spheroid growth while inducing significant apoptosis. Dual BRD4 and EGFR degradation was more pronounced in sensitive cells but retained strong efficacy in resistant cells, highlighting BE-PRO’s potential to overcome EGFR TKI resistance. BERD was developed as an in situ depot system enabling sustained release of both PROTACs for six days, thereby enhancing therapeutic efficacy at lower doses while maintaining physicochemical stability and injectability. In vivo, BERD achieved the highest tumor growth inhibition, significantly reducing tumor volume and weight while exhibiting minimal systemic toxicity. Histological and immunohistochemical analyses confirmed decreased proliferation (Ki-67), reduced angiogenesis (CD31), diminished EGFR expression, and pronounced disruption of tumor cell architecture in BERD-treated tumors compared to controls. Collectively, these findings demonstrate the potential of BE-PRO and its long-acting BERD formulation as a promising therapeutic approach for both sensitive and resistant NSCLC, offering a foundation for future translational and clinical development.

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