Background: In ELECT, LAN significantly reduced the need for short-acting OCT rescue therapy for symptomatic control of CS in NET patients (pts) vs placebo (PBO) (primary result). Here we present flushing and diarrhea symptom data and biochemical response for pts with or without prior OCT use from ELECT. Methods: Adults with histopathologically-confirmed NET and history of stable CS (diarrhea and/or flushing) who were OCT-naive or responsive to OCT long-acting release (LAR) (≤30 mg q4W) or short-acting OCT (≤600 μg daily) were randomized to LAN 120 mg (SC q4W) or PBO for 16 wks. Pts administered SC OCT if needed and recorded daily frequency and severity of symptoms using Interactive Voice/Web Response System for 1 month pre-randomization and throughout the study. 24-hr urinary 5-hydroxindoleacetic acid (5HIAA) and plasma chromogranin A (CgA) were assessed at baseline and wk 12. Results: Of 115 pts randomized, 51 were OCT-naive and 64 received prior OCT. The least squares (LS) mean percentages of days with moderate/severe diarrhea and/or flushing were lower in both naive and prior OCT LAN pts vs naive and prior OCT PBO pts; LS mean difference (LAN-PBO) was significant in the naive group (Table). By week 12, 5HIAA and CgA levels dropped by ≥30% to normal in 35.3% and 15.8% of naive LAN pts and 28.6% and 4.5% of prior OCT LAN pts; 5HIAA and CgA reductions were seen in 15.4% and 21.4% of naive PBO pts and 5HIAA in 7.1% of prior OCT PBO pts. Conclusions: Pts showed improvement in CS symptoms of flushing and diarrhea and reduction in 5HIAA levels with LAN treatment, indicating efficacy of LAN regardless of prior OCT use. Transition from OCT to LAN was well tolerated among prior OCT pts in ELECT. Clinical trial information: NCT00774930