Phase II study of ibrutinib in advanced carcinoid and pancreatic neuroendocrine tumors.

Abstract

434 Background: Ibrutinib is an orally administered, inhibitor of Bruton’s tyrosine kinase (Btk). Preclinical data suggest that mast cells are recruited with neuroendocrine tumors (NETs) where they remodel the stroma and stimulate angiogenesis, driving macroscopic tumor expansion. Ibrutinib inhibits mast cell degranulation, and has been associated with regression of a mouse insulinoma model. Methods: A prospective, phase II trial evaluated patients with advanced GI/lung NETs and pNETs who had evidence of progression within 12 months of study entry on at least one prior therapy. Patients received ibrutinib 560mg daily until unacceptable toxicity, progression of disease, or withdrawal of consent. Primary endpoint was objective response rate. Results: 20 patients were enrolled on protocol from November 2015 – December 2017 (15 carcinoid and five pNETs). No patients experienced objective response. Median PFS was 3.1 months. A total of 43 drug related AEs were captured as probably or definitely associated with ibrutinib. Five patients experienced probably or definitely related grade 3 AEs and one patient experienced a probably related grade 4 AE. Five patients discontinued treatment prior to radiographic assessment. Conclusions: Ibrutinib does not show significant evidence of activity when compared to other agents (e.g. Everolimus) in well-differentiated gastroenteropancreatic and lung NETs. Clinical trial information: 02575300.