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Endocrine Abstracts (2020) 70 AEP612 | DOI: 10.1530/endoabs.70.AEP612

ECE2020 Audio ePoster Presentations Pituitary and Neuroendocrinology (217 abstracts)

IGF-I variability and its association with demographic and clinical characteristics in patients with acromegaly treated with injectable somatostatin receptor ligands (SRLs); results from OPTIMAL, an international prospective phase 3 study

Susan Samson 1 , Lisa Nachtigall 2 , Maria Fleseriu 3 , Ehud Ur 4 , Mark E Molitch 5 , William Ludlam 6 , Gary Patou 7 , Asi Haviv 7 , Yossi Gilgun-Sherki 7 , Nienke Biermasz 8 , Christian J Strasburger 9 , Laurence Kennedy 10 & Shlomo Melmed 11


1Baylor College of Medicine, Houston, United States; 2MGH Neuroendocrine Clinical Center, Chestnut Hill, United States; 3Oregon Health & Science University, Portland, United States; 4UBC, Vancouver, Canada; 5Northwestern University, Evanston, United States; 6Chiasma, Mountain Lakes, United States; 7Chiasma, Waltham, United States; 8Leiden University Medical Center (LUMC), Leiden, Netherlands; 9Charité – Campus Mitte (Berlin), Berlin, Germany; 10Cleveland Clinic Foundation, Cleveland, United States; 11Cedars-Sinai Medical Center, Los Angeles, United States


Background: Most patients responding to injectable somatostatin receptor ligands exhibit IGF-I variability around the upper limit of normal (ULN) during long-term follow up. These fluctuations are thought to result from assay variability, nutrition, comorbid conditions, concomitant medications and other unknown factors. The magnitude and factors affecting this variability arenot well understood in patients with acromegaly treated with injectable SRLs.

Methods: IGF-I levels of patients responding to and stably treated with injectable SRLs were measured over time in the CHIASMA OPTIMAL phase 3 study. Two time periods were assessed – Period 1, three assessments during screening before randomization to octreotide capsules (n = 56); and Period 2, multiple assessments up to week 36, in patients rescued with SRL injections for ≥ 12 weeks (n = 21).Time from last injection to each assessment in period 1 [Screening visits 1 and 2 (SV1 & SV2) and Baseline] was on average 6.8 ± 10.7 (s.d.), 15.8 ±2.7, and 29.0 ± 1.8 days, respectively. Correlation with demographics and Baseline characteristics including age, gender, weight, BMI, and residual tumor size to IGF-I variability was assessed. Percent change for each individual patient from Minimal to Maximal IGF-I values within each period was computed. The overall population mean was calculated (lowest value as the denominator and all other values as a percentage above this value).

Results: Overallmean within-patient percent change of IGF-I levelsduring Period 1 was 20.48 ± 15.56 (range: 0.6–81). Mean IGF-I levels for SV1, SV2 and Baseline were 0.78 ± 0.18,0.79 ± 0.18, and 0.85 ± 0.22 × ULN respectively. Overall increase in mean IGF-I levels from SV1 to Baseline (longest time interval) was statistically significant (P = 0.0002; paired T-test). Overall mean within-patient percent change of IGF-I levels during Period 2 was 15.27 ± 12.20 (range: 0–41.5). Mean duration of follow up during this period, after patients were already treated for 12 weeks with oral SRL, was 4.38 months (range: 2.67–7.47). The variability in Period 2 was similar to that observed in the entire sample evaluated in Period 1. No significant correlation was found between individual IGF-I percent change and any demographic and Baseline characteristics examined.

Conclusion: IGF-I levels fluctuate in patients with acromegaly responsive to injectable SRLs. These fluctuations can be up to 81% higher than the lowest (most controlled) value, with an average increase of approximately 20%. Significant IGF-I increases were observed at the end of the injection interval of long acting SRLs.

Volume 70

22nd European Congress of Endocrinology

Online
05 Sep 2020 - 09 Sep 2020

European Society of Endocrinology 

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