Preclinical Development Of Dual Egfr Dna Targeting Agent In Glioblastoma

Download or read book Preclinical Development of Dual EGFR/DNA Targeting Agent in Glioblastoma written by Zeinab Sharifi and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Glioblastoma (GBM) is one of the most frequent, invasive and devastating primary brain tumors with a median overall survival rate of about 15 months despite aggressive multimodality treatment with surgery, concurrent radiation therapy (RT) and chemotherapy (TMZ). Characteristics such as heterogeneity, invasion, acquired resistance, presence of tumor stem cells that lead to recurrence of these tumors are among the reasons that has made GBM the most difficult brain cancer to treat and has left scientists and clinicians with limited therapy options. Importantly, overcoming the complexity seen in GBM with single-targeted drugs has proven to be challenging. It is in this context that we are using a multi-targeted approach termed “combi-targeting” or “combi-molecules” to target more than one oncogenic driver in tumors cells. Epidermal growth factor receptor (EGFR) dysregulation plays a critical role in GBM progression and DNA repair. Likewise, targeting DNA in tumor cells has been of a great interest in clinical management of solid tumors. We therefore investigated the strategy to combine a quinazoline ring (EGFR inhibitory arm) along with a chloromethyl group (DNA damaging arm) in one combi-molecule. By using this approach, we aim to not only enhance the potency of chemotherapeutic agents by simultaneously damaging DNA and inhibiting the EGFR pathway but also we aimed to target DNA repair by inhibition of the EGFR pathway which is known to be involved in DNA repair. Here, we showed that oral administration of the dual EGFR-DNA damaging combi-molecule ZR2002 at doses up to 150mg/kg using either alternate or continuous treatment schedule was safe in athymic mice that have intact DNA repair pathway. ZR2002 was detected in the brain and plasma of mice using HPLC and LC/MS analysis. Interestingly, MALDI IMS confirmed the presence of ZR2002 and its metabolite (ZR01) in the brain of nude mice with intracranial tumors. Given the central role of GBM stem cells (GSCs) in tumor progression, chemo- and radioresistance and tumor relapse, we used patient-derived GSC neurosphere cultures, as a model to also examine the effects of ZR2002. ZR2002, inhibited neurosphere formation of GSCs cultures and induced significant DNA damage in these cell lines starting at a low concentration (1 μM). Interestingly, this novel combi-molecule hindered the proliferation of TMZ-sensitive and resistant mesenchymal in vivo derived GSC sublines. We also tested for the first time and elucidated the mechanism of action of ZR2002 and studied its ability to kill GBM established cell lines with different EGFR levels. ZR2002 induced potent submicromolar growth inhibitory effects in U87/EGFR isogenic cell lines and hindered their clonogenic potential. ZR2002 was also able to induce significant DNA damage in these cell lines at a low concentration (0.6 μM). ZR2002 inhibited EGF-induced autophosphorylation of EGFR/EGFRvIII and downstream Erk1/2 phosphorylation, significantly increased DNA strand breaks and induced wild-type TP53 activation in the established and stem cell lines tested. Its cytotoxic effects were mediated through a p53-dependent mechanism. Most importantly, oral administration of ZR2002 significantly increased survival in both the U87/EGFRvIII and TMZ-resistant GSC intracranial models. In sum, ZR2002, a unique binary EGFR/DNA combi-molecule with submicromolar potency imparts direct inhibition of EGFRvIII-induced proliferation and tumor growth. Its broad anti-proliferative, DNA-damaging activity in GSCs and in vivo anti-tumor activity provide proof-of-concept for its clinical evaluation in GBM"--