Endocrine Abstracts

Introduction: The PRIMARYS study demonstrated primary treatment with lanreotide Autogel 120 mg could achieve favourable tumour and hormone response rates in a large cohort of acromegalic patients. Here, we further interrogate the PRIMARYS database on the relationship between the tumour volume responsiveness and hormonal control.

Methods: PRIMARYS was an international, multicentre, open-label, single-arm study of 90 treatment-naïve acromegalic patients with pituitary macroadenoma receiving primary therapy with lanreotide Autogel 120 mg every 28 days for 48 weeks. Tumour volume reduction (TVR) and hormonal status were measured at 12, 24, and 48 weeks after treatment initiation. The primary endpoint was % of patients with therapeutic tumour response (i.e., ≥20% TVR from baseline) at week 48. Correlation analyses of GH and IGF1 vs TV changes at 48 weeks were performed. Descriptive statistics were used to assess shifts in therapeutic tumour response rates based on hormonal control status at each time point.

Results: Correlation analyses showed that the greater the reduction in GH or IGF1 level, the greater the reduction in tumour volume (correlation coefficients, 0.51 and 0.49, respectively; P<0.0001 for both). At each study visit, more patients with hormone control (GH <2.5 ng/ml and normal IGF1) achieved tumour response than those without hormone control (Fig. 1). The TVR response rates did not change greatly over consecutive visits: ranging from 69 to 73% of patients with hormone control, and 41 to 50% of those without hormone control.

Conclusions: These data suggest there is a relationship between tumour and hormone responses to primary lanreotide Autogel 120 mg treatment in acromegalic patients. The data also suggest the relationship may exist as early as 12 weeks and may not necessarily be dependent on longer treatment duration.