American Association for Cancer Research
ccr-22-0533_supplemental_figure_6_suppfs6.pdf (1.17 MB)

Supplemental Figure 6 from Myosin Light-Chain Kinase Inhibition Potentiates the Antitumor Effects of Avapritinib in PDGFRA D842V-Mutant Gastrointestinal Stromal Tumor

Download (1.17 MB)
journal contribution
posted on 2023-06-01, 08:21 authored by Ferdinand Rossi, Mengyuan Liu, Andrew Tieniber, Mark S. Etherington, Andrew Hanna, Gerardo A. Vitiello, Nesteene J. Param, Kevin Do, Laura Wang, Cristina R. Antonescu, Shan Zeng, Jennifer Q. Zhang, Ronald P. DeMatteo

Supplemental Figure 6.Cell survival of GIST T1 cells treated with imatinib or avapritinib for 72h in complete media.Each data point represents an average of 10 wells.


National Institutes of Health (NIH)

David Foundation (קרן דוד)

Betsy Levine-Brown and Marc Brown

GIST Cancer Research Fund (GCRF)



To create an in vivo model of PDGFRA D842V-mutant gastrointestinal stromal tumor (GIST) and identify the mechanism of tumor persistence following avapritinib therapy. We created a patient-derived xenograft (PDX) of PDGFRA D842V-mutant GIST and tested the effects of imatinib, avapritinib, and ML-7, an inhibitor of myosin light-chain kinase (MYLK). Bulk tumor RNA sequencing and oncogenic signaling were evaluated. Apoptosis, survival, and actin cytoskeleton were evaluated in GIST T1 cells and isolated PDX cells in vitro. Human GIST specimens were analyzed for MYLK expression. The PDX was minimally responsive to imatinib but sensitive to avapritinib. Avapritinib therapy increased tumor expression of genes related to the actin cytoskeleton, including MYLK. ML-7 induced apoptosis and disrupted actin filaments in short-term cultures of PDX cells and decreased survival in GIST T1 cells in combination with imatinib or avapritinib. Combined therapy with ML-7 improved the antitumor effects of low-dose avapritinib in vivo. Furthermore, MYLK was expressed in human GIST specimens. MYLK upregulation is a novel mechanism of tumor persistence after tyrosine kinase inhibition. Concomitant MYLK inhibition may enable the use of a lower dose of avapritinib, which is associated with dose-dependent cognitive side effects.

Usage metrics

    Clinical Cancer Research





    Ref. manager