Abstract 273: KDM1A inhibition enhances chemotherapy response in glioblastoma via downregulation of DNA repair pathways
Authors: Palacios Bridgitte E. , Pitta-Venkata Prabhakar , Chen Yihong , Viswanadhapalli Suryavathi , Pratap Uday P. , Gruslova Aleksandra , Suzuki Takayoshi , Vadlamudi Ratna K. , Brenner Andrew , Sareddy Gangadhara R. 
Published: August 2019

Abstract
Background: Glioblastomas (GBM) have dismal survival rates (1 year-34.6% and 5 year-4.75%) and affect 13,000 patients yearly. Standard of care treatment consists of surgical resection, external beam radiation therapy, adjuvant chemotherapy with temozolomide (TMZ), and tumor treating fields. Despite heavy investment in therapy, all patients will eventually succumb to their disease. Oncogenic and epigenetic signaling mechanisms may modulate DNA damage response (DDR) in tumors and contribute to chemo and radiation therapy resistance. Recently, we have shown that lysine-specific histone demethylase 1A (KDM1A), an epigenetic regulator, is overexpressed in GBM. In this study, we tested the hypothesis that KDM1A is essential for DDR, and that inhibition of KDM1A induces DNA repair deficiency and sensitizes GBM to TMZ therapy.
Methods: To study the role of KDM1A in GBM cells, we have generated KDM1A knockout (KDM1A-KO) cells using the CRISPR/Cas9 system and KDM1A-shRNA transfected primary GBM cells (KDM1A-KD). Effect of KDM1A-KO, -KD or KDM1A inhibitor (NCD-38) on TMZ sensitization was studied using cell viability and survival assays. Mechanistic studies were conducted using RNA-seq, RT-qPCR and western blot analysis. The blood-brain barrier (BBB) permeability of NCD-38 was studied by pharmacokinetic (PK) and brain bioavailability studies. Further, the in vivo efficacy of KDM1A inhibitor was studied using orthotopic models of GBM.
Results: Cell viability and survival assays showed that knockout or pharmacological inhibition of KDM1A sensitized GBM cells to TMZ treatment. KDM1A expression is increased in GBM cells after treatment with TMZ. RNA-seq analysis revealed a decreased expression of several genes involved in DNA repair, including MGMT, RAD51, and MRE11A in NCD-38 treated cells compared to control. PK and brain bioavailability studies following a single intravenous dose (IV, 1 mg/kg) and per oral administration (PO, 10 mg/kg) of NCD-38 demonstrated that NCD-38 has favorable PK properties and exhibited a significant penetration of the BBB, with a total brain/plasma ratio of more than two at all tested time points. Further, KDM1A inhibition significantly reduced the in vivo tumor progression in established and primary GBM orthotopic models.
Conclusions: Our results provide evidence that KDM1A contributes to chemotherapy resistance in GBM by modulating DNA repair pathways and the use of KDM1A inhibitor in conjunction with standard chemotherapy will serve as novel therapy for GBM patients.
Citation Format: Bridgitte E. Palacios, Prabhakar Pitta-Venkata, Yihong Chen, Suryavathi Viswanadhapalli, Uday P. Pratap, Aleksandra Gruslova, Takayoshi Suzuki, Ratna K. Vadlamudi, Andrew Brenner, Gangadhara R. Sareddy. KDM1A inhibition enhances chemotherapy response in glioblastoma via downregulation of DNA repair pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 273.