Abstract LB219: DCLK1 is a novel therapeutic target for gastric and colorectal cancers as demonstrated by patient-derived organoids assays
Authors: Qu Dongfeng , Shi Jinsen , Cao Zhiyun , BAnnerman-Menson Eddie , Weygant Nathaniel , Houchen Courtney 
Published: April 2024

Abstract
Gastrointestinal cancers, including gastric cancer (GC) and colorectal cancer (CRC), continue to be devastating diseases despite advances in screening, early detection, and removal of pre-neoplastic and early cancerous lesions. Even with advancements in targeted chemotherapy and immunotherapies, advanced and metastatic diseases continue to be responsible for the high mortality associated with GC and CRC. Newer, safer, and more effective therapies to prevent, inhibit, or reverse advanced disease progression are urgently needed. Doublecortin-like kinase 1 (DCLK1) is a microtubule associated protein kinase that has been reported to drive tumor initiation, progression, metastasis, and drug resistance in many solid tumor cancers including GC and CRC, where it is upregulated in patient tumors and associated with poor overall survival. An anti-DCLK1 monoclonal antibody has demonstrated potential therapeutic activity against CRC. In this study, we established patient-derived organoids (PDOs) to evaluate the effects of inhibiting DCLK1 kinase activity (DCLK1-IN-1) or targeting DCLK1 with a highly specific CAR-T cells on the treated PDOs. Two GC PDOs were treated with various concentrations of DCLK1 kinase inhibitor DCLK1-IN-1 (0-32 μM) for 72 hrs, viability of the PDOs were determined, histochemistry and immunohistochemistry staining were used to image the live cells and DCLK1 expression. For CRC PDOs, five CRC PDOs were cultured in the presence or absence of PBMC, treated with Mock CAR-T cells or DCLK1 CAR-T cells (three doses) for 4 days. Tumor size, tumor total area, and viability of these PDOs were determined. Here, we demonstrate that treating GC PDOs with DCLK1 kinase inhibitor resulted in a significant dose-dependent inhibition in PDO numbers in both PDOs (two-way ANOVA P&lt;0.0001), a decrease of cell viability, revealing IC50 values of 7.566 and 9.958 μM respectively, and a near total loss of GC PDO viability at 10 μM using CellTiterGlo assay. In CRC PDOs, two of five CRC PDOs showed a significant decrease in total tumor size, tumor areas, and an increase in cell death measured by the DRAQ7 method. Compared to Mock CAR-T cells, treatment with DCLK1 CAR-T cells resulted in a dose dependent decrease of tumor size and total tumor area, with more than a 50% reduction at the 50000 cells dose (p&lt;0.05). Treatment with DCLK1 CAR-T cells also resulted in a dose dependent increase in cell death, with approximately 20% cell death without PBMC, and 50% cell death with PBMC at the 50000 cells dose (p&lt;0.05). These results suggest that targeting DCLK1 represents a potential novel therapeutic strategy for GI cancers, especially in combination with FDA approved drugs: 5-fluorouracil (5-FU) or Gefitinib.
Citation Format: Dongfeng Qu, Jinsen Shi, Zhiyun Cao, Eddie BAnnerman-Menson, Nathaniel Weygant, Courtney Houchen. DCLK1 is a novel therapeutic target for gastric and colorectal cancers as demonstrated by patient-derived organoids assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB219.