Abstract 4741: Targeting tumor growth in a medullary thyroid carcinoma mouse model using a combinatorial treatment with a tyrosine kinase inhibitor and histone deacetylase inhibitor

Abstract

Abstract Neuroendocrine tumors are rare forms of cancers arising from hormone-producing cells that are scattered throughout the body. Medullary thyroid carcinoma (MTC) originates from the thyroid gland parafollicular cells. Treatment options for progressive, metastatic MTC patients are limited to the recently FDA-approved tyrosine kinase inhibitors (TKIs), Vandetanib and Cabozantinib, which target multiple receptor tyrosine kinases, including VEGFR2. However, the efficacy of TKIs is limited and development of TKI resistance is common. Here we examined, the effect of a combinatorial drug therapy using the TKI, Nintedanib, and the histone deacetylase (HDAC) inhibitor, Romidepsin, on MTC growth in the NSE/p25-gfp bi-transgenic mouse line, an inducible MTC mouse model (see Pozo et al. 2013). The TKI- and HDAC inhibitors were administered intraperitoneally for 3 weeks and tumor growth progression was monitored using a T2 weighted magnetic resonance imaging on a 7 Tesla system. Tumor tissues were analyzed for oncogenic signaling pathways by immunoblotting and immunohistochemistry. We find that co-administration of Nintedanib and Romidepsin stops tumor growth and increases the number of necrotic foci within the tumor tissue. Interestingly, Nintedanib treatment alone reduced tumor vascularization as shown by decreased density of the vascular marker, CD31, but did not stop parafollicular cell proliferation. Taken together, these results suggest that a combinatorial drug therapy with a TKI- and an HDAC inhibitor may be a more efficient strategy to target MTC progression and overcome recurrence. Citation Format: Karine Pozo, Stefan Zahler, Chunfeng Tan, Keisuke Ishimatsu, Masaya Takahashi, James Bibb. Targeting tumor growth in a medullary thyroid carcinoma mouse model using a combinatorial treatment with a tyrosine kinase inhibitor and histone deacetylase inhibitor. [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 4741.