MON-314 Analysis of Adverse Events in Adult Patients with Acromegaly Receiving Oral Octreotide Capsules: Results from the Phase 3, Randomized, Double-Blind, Placebo-Controlled CHIASMA OPTIMAL Study

Distinguishing non-specific signs and symptoms of acromegaly from treatment emergent adverse events (TEAEs) in patients treated with somatostatin receptor ligands has proven difficult given limited data from placebo-controlled studies. The phase 3 Octreotide capsules versus Placebo Treatment In MultinationAL centers (OPTIMAL) study provides a novel data set to evaluate the incidence of adverse events from patients randomized to octreotide capsules or placebo. A multinational, randomized, placebo-controlled study was conducted in 56 adult patients with active acromegaly. Eligible patients were ≥18 years of age, had active disease (IGF-I ≥1.3 x ULN after last pituitary surgery), and an average IGF-I ≤1.0 x ULN in response to a stable dose of somatostatin receptor ligand injection. Patients were randomized to octreotide capsule or placebo (28 per group) for 36 weeks, followed by an optional open-label extension for up to 1 year. Safety and tolerability were evaluated based on incidence of AEs, including incidence of new or worsening adverse events of special interest (AESIs). In this study, the safety profile of octreotide capsules was consistent with the known safety profile of injectable octreotide (Melmed et al 2015). No new or unexpected safety signals were detected. Nearly all patients (55/56) experienced a TEAE (28 patients [100.0%] in the octreotide capsule group and 27 patients [96.4%] in the placebo group). Thirty-three patients (58.9%) experienced a TEAE considered to be related to study drug by the blinded PI (64.3% of the octreotide capsule group [18 patients, 40 events] and 53.8% of the placebo group [15 patients, 41 events]). TEAEs with an incidence ≥5% that were more common in the octreotide capsule group vs placebo group included GI disorders, increased blood glucose, sinusitis, osteoarthritis, and cholelithiasis. TEAEs with an incidence ≥5% that were more common in the placebo group vs octreotide capsule group included arthralgia, headache, fatigue, hyperhidrosis, and peripheral swelling. GI disorders were the most common TEAE, reported in 64% of all patients (36/56) and at similar rates between octreotide capsule (68%) and placebo groups (61%). AESIs (defined as new or worsening signs of acromegaly) were observed in 15 patients (53.6%, 34 events total) in the octreotide capsule group and more frequently in 26 patients (92.9%, 82 events total) in the placebo group. In this study, the safety profile of octreotide capsules was consistent with the known safety profile of injectable octreotide. Most patients receiving octreotide capsules or placebo demonstrated TEAEs, although the profile of most common TEAEs varied between groups. TEAEs observed in the placebo group may be indicative of underlying disease activity. Further analysis may elucidate the difference between treatment related AEs and signs/symptoms of active disease in acromegaly.