Abstract
PurposePRIMARYS (NCT00690898) was a 48-week, open-label, phase 3b study, evaluating treatment with the somatostatin receptor ligand lanreotide autogel (stable dose: 120 mg/28 days) in treatment-naïve patients with growth hormone (GH)-secreting pituitary macroadenoma. This post hoc analysis aimed to evaluate factors predictive of long-term responses.MethodsPotential predictive factors evaluated were: sex, age, and body mass index at baseline; and GH, insulin-like growth factor-1 (IGF-1), and tumor volume (TV) at baseline and week 12, using univariate regression analyses. Treatment responses were defined as hormonal control (GH ≤ 2.5 µg/L and age- and sex-normalized IGF-1), tight hormonal control (GH < 1.0 µg/L and normalized IGF-1), or ≥ 20% TV reduction (TVR). Receiver-operating-characteristic (ROC) curves were constructed using predictive factors significant in univariate analyses. Cut-off values for predicting treatment responses at 12 months were derived by maximizing the Youden index (J).ResultsAt baseline, older age, female sex, and lower IGF-1 levels were associated with an increased probability of achieving long-term hormonal control. ROC area-under-the curve (AUC) values for hormonal control were high for week-12 GH and IGF-1 levels (0.87 and 0.93, respectively); associated cut-off values were 1.19 μg/L and 110% of the upper limit of normal (ULN), respectively. Results were similar for tight hormonal control (AUC values: 0.92 [GH] and 0.87 [IGF-1]; cut-off values: 1.11 μg/L and 125% ULN, respectively). AUC and J values associated with TVR were low.ConclusionsThe use of predictive factors at baseline and week 12 of treatment could inform clinical expectations of the long-term efficacy of lanreotide autogel.
Highlights
Is a disease characterized by the hypersecretion of growth hormone (GH)/insulin-like growth hormone-1 (IGF-1), typically as a result of a benign pituitary adenoma [1]
A total of 90 patients were enrolled in the PRIMARYS study and received treatment, and 18 of these withdrew due to an insufficient IGF-1 response [4]
Post-hoc analyses were undertaken with data from the PRIMARYS study to determine whether treatment responses to lanreotide autogel at 12 months could be predicted from baseline characteristics and/or from week-12 hormone concentrations and tumor volume (TV)
Summary
Is a disease characterized by the hypersecretion of growth hormone (GH)/insulin-like growth hormone-1 (IGF-1), typically as a result of a benign pituitary adenoma [1]. Long-acting forms of first-generation somatostatin receptor ligands (SRLs) are a well-established medical treatment for acromegaly. They are recommended in patients who do not achieve an adequate response following surgery, as well as in the first-line treatment of patients who are not suitable for or who refuse surgery [2, 3]. Long-acting SRLs have proven benefits in patients with acromegaly, reducing tumor volume (TV), decreasing GH and IGF-1 levels, and improving comorbidities [4,5,6,7,8]. Not all patients respond to SRL treatment.
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