Abstract A173: Long-term responders to epigenetic modulators: abexinostat and pazopanib

Characterization of long-term responders in a phase I trial evaluating the role of epigenetic modulation of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor by using a histone deacetylase abexinostat in combination with pazopanib to enhance response and reverse resistance. Patients and Methods: Pazopanib was administered once a day on days 1 to 28 and abexinostat was administered orally twice a day on days 1 to 5, 8 to 12, and 15 to 19 (schedule A) or on days 1 to 4, 8 to 11, and 15 to 18 (schedule B). Dose escalation (3 + 3 design) in all solid tumors was followed by dose expansion in renal cell carcinoma (RCC). Histone acetylation and HDAC2 expression were correlated long-term responders, u003e1y). Results: Fifty-one patients including RCC (N = 22) were enrolled, including 30 (59%) with one or more lines of prior VEGF-targeting therapy. Toxicities and PK studies were reported previously. 7 pts had response u003e 23 months (23-60+), including 5/22 patients with RCC, and one patient with medullary thyroid and thymic neurondocrine cancer. Long-term response was associated with high HDAC2 expression in PBMCs, increased histone acetylation, and modulation of VEGF level. Conclusion: Epigenetic modulation with HDAC inhibitors is strongly dependent on host factors to promote long-term benefit to abexinostat and pazopanib in pretreated patients. Citation Format: Rahul Aggarwal, Nela Pawlowsk, Jennifer Grabowsky, Armand Harb, Kamran Abri-Lavasani, Scott Thomas, Pamela N. Munster. Long-term responders to epigenetic modulators: abexinostat and pazopanib [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A173.