Longer term efficacy of lanreotide autogel/depot (LAN) for symptomatic treatment of carcinoid syndrome (CS) in neuroendocrine tumor (NET) patients from the ELECT open label study

Abstract

Background: In ELECT, LAN significantly reduced the need for short-acting octreotide rescue medication for symptomatic control of CS in NET patients vs placebo (PBO) in the 16-wk double-blind (DB) phase (primary result). Here we compare patient-reported symptoms in the DB vs 32-wk initial open-label phase (IOL). Methods: Adults with histopathologically confirmed NET and history of CS with/without prior somatostatin analog (SSA) use were randomized to DB LAN 120 mg or PBO every 4 wks for 16 wks followed by a 32-wk IOL on LAN. Patients recorded daily the frequency and severity of diarrhea and/or flushing by Interactive Voice (Web) Response System for 1 month pre-randomization through IOL.Mean composite symptom scores (frequency x severity) in DB vs IOL were analyzed posthoc. Analysis of covariance models (ANCOVA) were used for these analyses with baseline symptoms, prior SSA, and country as factors. Urinary 5-hydroxyindoleacetic acid (u5HIAA) values were log transformed. Results: Of 115 randomized (n = 59 LAN, n = 56 PBO), 56 LAN- and 45 PBO-treated patients, switched to LAN, were available for IOL analysis. Among patients initially on LAN, composite diarrhea scores improved significantly from DB to IOL (mean difference 0.7, 95% CI: 0.22, 1.20; p = 0.005) and were not significantly different for flushing (mean difference -0.2, 95% CI: -1.25, 0.80) or diarrhea and flushing (mean difference 0.5, 95% CI: -0.69, 1.67). As expected, the mean difference in composite scores for diarrhea (1.1, 95% CI: 0.49, 1.65), flushing (1.1, 95% CI: 0.19, 1.93), and diarrhea / flushing (2.1, 95% CI: 0.91, 3.35) reflected significant improvement from DB to IOL for patients initially on PBO (P-values <0.05). Mean (95% CI) differences in u5HIAA between DB wk 12 and IOL wk 48 were -14.75 mumol/d (-27.02, 56.51) for LAN (DB) - LAN (IOL) and 73.96 mumol/d (-11.77, 159.7) for PBO (DB) - LAN (IOL). Frequency of treatment-emergent adverse events (AEs) during IOL by DB group (LAN, PBO) was 69.6% vs 71.1%. The AE profile during IOL was similar to DB. Conclusions: Improved control of diarrhea and flushing in CS patients during initial 16 wks of LAN was sustained through wk 48 of this phase 3 study.