Endocrine Abstracts

Background: The LANTERN study (NCT02493517) has demonstrated that lanreotide autogel (LAN ATG) was non-inferior to lanreotide prolonged release (LAN PR) in Chinese patients with active acromegaly. This post hoc analysis of the LANTERN study assessed the impact of tumor size on treatment effect.

Design: In the LANTERN study, LAN ATG was started at 90 mg and subsequently titrated according to GH and IGF-1 levels for 32 weeks. Tumor diameters > 10 mm were classified as macroadenoma (Group I) and ≤ 10 mm as microadenomas (Group II) using centralized blinded review of magnetic resonance imaging (MRI) scans. This post hoc analysis focuses on the efficacy of LAN ATG in Group I vs Group II.

Results: There were 38 patients in Group I and 14 patients in Group II. Group I had higher Baseline GH level than group II [median (Q1,Q3): 21.57(8.05, 32.06) vs 6.02 (4.27, 15.02); P = 0.004]. Meanwhile, mean Baseline age-adjusted IGF-1 SDS was comparable between Group I and Group II [15.76 ± 6.20 vs 13.67 ± 6.17; P = 0.285]. For change from Ba seline at week 32, GH levels decrease in Group I was approximately half of that in Group II [–9.39 (95% CI –14.89, –3.88) vs –16.48 (95% CI – 25.77,–7.19); pw = 0.202]; IGF-1 SDS score decrease was significantly lower in Group I than in Group II [–4.95 (95% CI –6.81, –3.10) vs –10.01 (95% CI –13.09, –6.94); P = 0.007]. Furthermore, a lower proportion of patents in group I attained GH level ≤ 2.5 µg/l vs Group II (13.16%, 5/38 vs 50.00%, 7/14, P = 0.015); a smaller proportion of patients in Group I achieved normalized IGF-1 levels than in Group II (7.9%, 3/38 vs 35.7%, 5/14; P = 0.042). In patients with evaluable MRI results both at Baseline and post-treatment, 36.1% (13/36) patients in Group I achieved ≥ 20% reduction in tumor volume vs 46.2% (6/13) in Group II (P = 0.524). The rate of treatment-emergent adverse events (TEAEs) was 94.7% in Group I and 92.9% in Group II. The rate of severe and moderate TEAEs was 57.9% in Group I and 50% in Group II. No treatment-emergent deaths were reported.

Conclusion: In this post hoc anaylsis, LAN ATG provided similar reductions in tumor volume ≥ 20% in patients with acromegaly regardless of tumor size(i.e. marcoadenoma or microadenoma). Biochemical control appeared to be better in patients with microadenoma than in those with macroadenoma, potentially due to imbalance in Baseline GH levels between the two groups. The safety profile of LAN ATG was consistent with previously reported data.