Abstract 5042: A CRISPR/Cas9 knockout screen identify novel drug resistance genes in AML

Abstract

Abstract Acute myeloid leukemia (AML) is a malignant hematopoietic disease and the most common type of acute leukemia in adults. Despite remarkable progress made in the therapy of AML, the mainstays of treatment have not significantly changed over the last 20 years. Technological advances have greatly accelerated genomic discovery and precision medicine holds promise to better tailor medications to AML with specific mutations. Importantly, one major obstacle to greater success with target therapy of leukemia is drug resistance. But the mechanisms underlying drug resistance in AML are poorly understood. The activating mutations of FLT3 are now recognized as the most common molecular abnormality in AML and FLT3ITD mutations are found in nearly 30% of AML patients. The poor prognosis of patients harboring FLT3 mutations renders FLT3 an obvious target of therapy. Quizartinib (AC220) is a potent and selective second-generation inhibitor of FLT3. It is in clinical trials for the treatment of relapsed or refractory FLT3ITD positive and negative AML patients and as a maintenance therapy. So far, those clinical trials have showed very promising result. However, drug resistance to AC220 has also been reported through the early clinical studies. To understand the underlying mechanisms of drug resistance to AC220, we undertook an unbiased approach with a novel CRISPR pooled library to screen new genes whose loss of function confer resistance to AC220. In our screen, we identified SPRY3 and GSK3 as positive hits and the related Wnt and FGF-Ras-ERK signaling activation as the major mechanisms to cause resistance to the FLT3 inhibitor AC220. In the next step, we will explore the detailed underlying mechanisms by which SPRY3 and GSK3 mutations lead to drug resistance to AC220. We will also confirm our findings in primary AML patient samples. Taken together, our study will provide new insight into signaling pathways that contribute to the acquired resistance in AML. The knowledge learned from this study may lead to the development of more efficient therapeutic avenues for AML. Citation Format: Jian Huang. A CRISPR/Cas9 knockout screen identify novel drug resistance genes in AML. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5042.