A phase 2 study of anastrozole in patients with oestrogen receptor and/progesterone receptor positive recurrent/metastatic granulosa cell tumours/sex-cord stromal tumours of the ovary: The PARAGON/ANZGOG 0903 trial

Background Hormonal therapies are commonly prescribed to patients with metastatic granulosa cell tumours (GCT), based on high response rates in small retrospective studies. Aromatase inhibitors (AIs) are reported to have high response rates and an accepted treatment option. We report the results of a phase 2 trial of an AI in recurrent/metastatic GCTs. Methods 41 patients with recurrent ER/PR + ve GCT received anastrozole 1 mg daily until progression or unacceptable toxicity. The primary endpoint was clinical benefit rate (CBR) at 12 weeks, evaluated by RECIST1.1 criteria. Secondary endpoints included progression-free survival (PFS), CBR duration, quality of life and toxicity. Results The CBR at 12 weeks in 38 evaluable patients was 78.9%, which included one (2.6%; 95% CI: 0.5–13.5%) partial response and 76.3% stable disease. Two additional patients without measurable disease were stable, based on inhibin. Median PFS was 8.6 m (95% CI 5.5–13.5 m). There were delayed responses observed after 12 weeks with a total of 4 pts. (10.5%; 95% CI 4.2%–24.1%) with a RECIST partial response; 23 (59%) patients were progression-free at 6 months. The adverse effects were predominantly low grade. Conclusions This is the first prospective trial of hormonal therapy in GCTs. Although there was a high CBR, the objective response rate to anastrozole was much lower than the pooled response rates of >70% to AIs reported in most retrospective series and case reports. PARAGON demonstrates the importance of prospective trials in rare cancers and the need to reconsider the role of AIs as single agents in GCTs.