ABSTRACT
Epithelial ovarian cancer (EOC) is among the top ten causes of cancer deaths worldwide, and is one of the most lethal gynecological malignancies in high income countries, with incidence and death rates expected to rise particularly in Asian countries where ovarian cancer is among the 5 most common cancers. Despite the plethora of randomised clinical trials investigating various systemic treatment options in EOC over the last few decades, both progression-free and overall survival have remained at approximately 16 and 40 months respectively. To date the greatest impact on treatment has been made by the use of poly (ADP-ribose) polymerase (PARP) inhibitors in women with advanced EOC and a BRCA1/2 mutation. Inhibition of PARP, the key enzyme in base excision repair, is based on synthetic lethality whereby alternative DNA repair pathways in tumor cells that are deficient in homologous recombination is blocked, rendering them unviable and leading to cell death. The Australia New Zealand Gynaecological Oncology Group (ANZGOG) is the national gynecological cancer clinical trials organization for Australia and New Zealand. ANZGOG's purpose is to improve outcomes and quality of life for women with gynecological cancer through cooperative clinical trials and undertaking multidisciplinary research into the causes, prevention and treatments of gynecological cancer. This review summarizes current ovarian cancer research and treatment approaches presented by Australian and New Zealand experts in the field at the 2020 ANZGOG webinar series entitled “Ovarian Cancer systems of Care”.
ABSTRACT
OBJECTIVE: A subset of patients with recurrent ovarian cancer (ROC) may benefit from antiestrogen therapy with higher response rates reported in tumors that are strongly estrogen receptor (ER)-positive (ER+). PARAGON is a basket trial that incorporates 7 phase 2 trials investigating the activity of anastrozole in patients with ER+ and/or progesterone receptor (PR)-positive (PR+) recurrent/metastatic gynecological cancers. METHODS: Postmenopausal women with ER+ and/or PR+ ROC, who were asymptomatic and had cancer antigen 125 (CA125) progression after response to first line chemotherapy, where chemotherapy was not clinically indicated. Patients received anastrozole 1 mg daily until progression or unacceptable toxicity. RESULTS: Fifty-four patients were enrolled (52 evaluable). Clinical benefit at three months (primary endpoint) was observed in 18 patients (34.6%; 95% confidence interval [CI]=23%–48%). Median progression-free survival (PFS) was 2.7 months (95% CI=2.1–3.1). The median duration of clinical benefit was 6.5 months (95% CI=2.8–11.7). Most patients progressed within 6 months of starting anastrozole but 12 (22%) continued treatment for longer than 6 months. Anastrozole was well tolerated. In the exploratory analysis, ER histoscores and the intensity of ER staining did not correlate with clinical benefit rate or PFS. CONCLUSION: A subset of asymptomatic patients with ER+ and/or PR+ ROC and CA125 progression had durable clinical benefit on anastrozole, with acceptable toxicity. Anastrozole may delay symptomatic progression and the time to subsequent chemotherapy. The future challenge is to identify the subset of patients most likely to benefit from an aromatase inhibitor and whether the clinical benefit could be increased by the addition of other agents.