Abstract Background Somatostatin receptor ligands (SRLs) are the mainstay pharmacotherapy for acromegaly. Patients report symptoms towards the end of the injection cycle. However, the correlation between IGF-I and patient-reported outcomes (PROMs) has not been evaluated in this context. Objective To determine IGF-I, PROMs, and SRL concentration variability in patients with acromegaly receiving long-acting SRLs. Methods Quality of life surveys, early and late phase (weeks 1 and 4 after SRL injection) biochemical markers, and SRL concentrations were obtained in 20 patients receiving monthly SRLs during two injection cycles. All IGF-I levels were measured using both mass spectrometry (LC-MS) and an immunoassay (IDS-iSYS). Results IGF-I concentrations were higher during late vs. early phase of cycle 2 using LC-MS (179.5±85.6 ng/mL vs. 154.8±80.2 ng/mL, p=0.045) and IDS-iSYS (201.2±86.3 ng/mL vs. 165.5±75.8 ng/mL, p=0.023) assays. In cycle 1, PASQ scores worsened in week 4 (18.10±11.96) compared to week 2 (15.53±9.94; p=0.011) and week 3 (15.00±12.49; p=0.021). SRL concentrations were lower during late phase (3563±1444 pg/mL vs. 2588±1085 pg/mL; p=0.008). Change in (Δ)SRL negatively correlated with ΔIGF-I IDS-iSYS (r=-0.385, p=0.047). ΔACROQoL physical significantly correlated with ΔIGF-I. Δsoluble alpha-klotho (sαKL) corelated with ΔPASQ score (r=0.337, p=0.034) and swelling (r=0.335, p=0.035). Conclusions IGF-I concentrations increased according to time since SRL injection. PROMs fluctuated, correlating with IGF-I and sαKL changes. Measuring IGF-I at the end of the injection cycle is advisable. Decreases in SRL concentration suggest phase-based differences in IGF-I concentrations. These findings inform personalized approaches to acromegaly, with titration of therapy based on individual IGF-I and/or PROMs fluctuation.
Remba-Shapiro et al. (Fri,) studied this question.