Purpose: There is currently no standard
therapy for
anaplastic thyroid cancer (ATC) and poorly differentiated
thyroid cancer (
PDTC), which account for two-thirds of
thyroid cancer-related deaths. Driver mutations in the PI3K/AKT and RAF/RAS/MEK/ERK pathways are common in ATC and
PDTC.
Histone deacetylases (HDAC) regulate
cancer initiation and progression. Our aim was to determine the therapeutic efficacy of simultaneously targeting these pathways in
thyroid cancer with a single agent and to evaluate
biomarkers of treatment response.Experimental Design:
CUDC-907 is a first-in-class compound, functioning as a dual inhibitor of HDACs and the PI3K/AKT pathway. We investigated its antiproliferative effect in vitro and in vivoResults:
CUDC-907 significantly inhibited cellular proliferation in
thyroid cancer cell lines, induced G2-M arrest with decreased levels of the checkpoint regulators
cyclin B1,
AURKA, AURKB, PLK1, and increased p21 and p27. Treatment induced apoptosis with increased
caspase-3/7 activity and decreased
survivin levels and decreased cellular migration and invasion.
CUDC-907 treatment caused H3 hyperacetylation and decreased HDAC2 expression. HDAC2 was upregulated in ATC and other
thyroid cancer histologic subtypes.
CUDC-907 treatment reduced both p-AKT and p-ERK1/2 levels. Finally,
CUDC-907 treatment, in a metastatic mouse model of
thyroid cancer, showed significant inhibition of growth and
metastases, and
tumors from treated mice had decreased HDAC2 expression, suggesting that this may be a useful
biomarker of response.Conclusions: Dual inhibition of HDAC and the
tyrosine kinase signaling pathways with
CUDC-907 is a promising treatment strategy for advanced, metastatic
thyroid cancer. Clin
Cancer Res; 23(17); 5044-54. ©2017 AACR.