Endocrine Abstracts

Introduction: PRIMARYS provided evidence for TVR with monthly LAN-ATG 120 mg in treatment-naïve acromegalic patients (63% achieved TVR ≥20% with a favourable safety profile). To help clinicians with therapeutic management of acromegaly, tumour responsive over time needs to be further explored.

Methods: PRIMARYS was an international, multicentre, open-label, single-arm study of 90 treatment-naïve acromegalic patients with pituitary macroadenoma receiving primary therapy with LAN-ATG 120 mg every 28 days for 48 weeks. TVR was measured at 12, 24, and 48 weeks on MRI central assessments. The primary endpoint was % of patients with relevant tumour responses (≥20% TVR from baseline) at week 48. Correlation analyses of baseline TV, TVRs at 12 and 24 weeks vs TVR at 48 weeks were performed. Descriptive statistics were used to assess shifts in TVR rates at various time points, and TVR over time stratified by TVR subgroups.

Results: There was a strong and statistically significant correlation between TVR at 12 and 24 vs 48 weeks (correlation coefficient 0.79 and 0.76, respectively; P<0.0001 for both). There was no correlation between baseline TV and TVR at 48 weeks. Among patients achieving a tumour response (TVR≥20%) at 12 and at 24 weeks, the majority maintained a response at 48 weeks (43/46 (93%) and 42/45 (93%) still responders at week 48). In patients with ≥20%TVR at last visit/week 48, the TVR changes at each previous study visit were consistently greater than those in patients with TVR<20% at last visit/week 48 (Fig. 1).

Conclusions: The current analyses suggest tumour responses to primary LAN-ATG 120 mg treatment after 12 and 24 weeks were equally-reliable predictors of tumour response after 48 weeks. The predictive value for longer term tumour response of TVR after only 12 weeks with LAN-ATG may help inform further treatment for an individual patient.