A Phase II Study of Ibrutinib in Advanced Neuroendocrine Neoplasms.

Ibrutinib is an orally administered inhibitor of Bruton's tyrosine kinase (Btk). Preclinical data suggest that mast cells are recruited within neuroendocrine neoplasms (NENs) where they stimulate angiogenesis and tumor growth. Ibrutinib inhibits mast cell degranulation and has been associated with regression of tumors in a mouse insulinoma model.A prospective, phase II trial evaluated patients with advanced GI/lung NENs and pancreatic NENs (pNENs) 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.20 patients were enrolled on protocol from November 2015 - December 2017 (15 advanced GI/lung NENs and 5 pNENs). No patients reached an objective response. Median PFS was 3.0 months. A total of 44 drug-related AEs were captured as probably- or definitely-associated with ibrutinib. 5 patients experienced probably- or definitely-related grade 3 AEs, and 1 patient experienced a probably-related grade 4 AE. Five patients discontinued treatment prior to radiographic assessment.Ibrutinib does not show significant evidence of activity in well-differentiated gastroenteropancreatic and lung NENs.