RF13 | PMON159 Long-term Efficacy and Safety Data for Oral Octreotide Capsules in Acromegaly: MPOWERED Trial Open-Label Extension Phase

BACKGROUND: Oral octreotide capsules (OOC) are a treatment option for patients with acromegaly in the United States. The MPOWERED trial (NCT02685709) showed that OOC were noninferior to injectable somatostatin receptor ligands (iSRLs; octreotide or lanreotide) in maintenance of biochemical control in patients previously responding to both treatments, as well as demonstrated improvements in patient-reported outcomes among patients receiving OOC. OBJECTIVE: Report long-term safety and efficacy outcomes with OOC from the open-label extension (OLE) of MPOWERED. METHODS: Patients were eligible for and could voluntarily enroll into the OLE if they had completed the 15-month core treatment phase of MPOWERED (6-month Run-in phase plus 9-month randomized controlled treatment [RCT] phase or, for OOC nonresponders during/at end of Run-in at participating sites, combination sub-study evaluating OOC in combination with cabergoline) and were adequately biochemically controlled per investigator assessment. Maintenance of response (definition: IGF-I <1.3×ULN; single timepoint) was assessed in each year of the OLE in patients responding at the start of that year. Additional analyses were performed on patients switching to OOC in the OLE from iSRLs in the core study. RESULTS: Sixty patients elected to enroll in the OLE (35 who received OOC and 19 who received iSRLs in the RCT phase, 6 from the combination sub-study). Median and maximal OOC exposure durations in the OLE were 2.2 and 3.5 years, respectively. A total of 94%, 90%, and 93% of patients receiving OOC monotherapy maintained biochemical response at the end of years 1, 2, and 3 of the OLE, respectively (using last observation carried forward imputation). Of patients switching from iSRLs to OOC during the OLE, 79% reported very good (47%) or excellent (32%) symptom control at the end of the OLE, compared with 47% (42% very good, 5% excellent) at the end of the RCT phase while receiving iSRLs. Patients switching from iSRLs also experienced significant improvements in the treatment convenience and treatment satisfaction domains (both P<0.05) of the Acromegaly Treatment Satisfaction Questionnaire. Median OOC compliance rate during the OLE was 99%. OOC safety during the OLE was consistent with that observed during the core study, with no new safety signals observed with long-term exposure. CONCLUSIONS: The OLE of MPOWERED demonstrated a high percentage (≥90%) of patients maintaining biochemical response while receiving OOC monotherapy with a favorable long-term safety profile of OOC. Those who switched from iSRLs to OOC demonstrated improvements in symptom control, treatment convenience, and treatment satisfaction. Presentation: Sunday, June 12, 2022 1:12 p.m. - 1:17 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.