A phase II study of combretastatin A4-phosphate (CA4P) in the treatment of well-differentiated, low- to intermediate-grade, unresectable, recurrent, or metastatic pancreatic, or GI neuroendocrine tumors/carcinoid (GI-NETs/PNETs) with elevated biomarkers.

Abstract

432 Background: GI-NETs/PNETs are highly vascular tumors. CA4P, a vascular disrupting agent (VDA), occludes tumor vasculature resulting in ischemic necrosis. Pre-clinical studies of CA4P have shown activity in GI-NETs/PNETs. Methods: OX4218s is a phase II, single-arm, open-label study (NCT02132468) of CA4P in patients (pts) with GI-NETs/PNETs with elevated biomarkers who relapsed during or after standard-of-care treatment. Pts received CA4P 60 mg/m2 IV on days 1, 8, and 15 of a 21-day cycle for 3 cycles. Primary endpoint was change in biomarkers from baseline. Secondary endpoints were safety, tolerability, symptoms, and QOL. Exploratory endpoints were ORR (RECIST 1.1). Pts achieving biomarker or symptom response were eligible for a rollover study. Results: 18 pts were enrolled; 7 subsequently entered the rollover study. Pts were on average aged 58 years, white (89%), male (50%) with ECOG status of 0-1. The majority (94%) had well-differentiated disease (GI-NETS 78%) and received prior Tx (94%). There were no meaningful changes in biomarkers. Eleven (61%) pts had stable disease (SD) and 1 (6%) had a partial response (PR). In the rollover study, 5 (71%) had SD, and 1 had SD for 14 cycles prior to progression (PD). 77% of pts had treatment-related AEs. Key grade 3-5 AEs (> 10%): anemia, abdominal pain, fatigue, hypertension, ALT and AST increases, with 1 grade 5 carcinoid syndrome. Conclusions: The primary endpoint was not met. However, the number of pts entering the rollover study and ORR suggest that CA4P conferred some activity and was generally safe and well tolerated. These findings suggest that due to their inherent variability, tumor biomarkers may not be an ideal endpoint for this population. Clinical trial information: NCT02132468. [Table: see text]