ESR1 and ovarian cancer: December 2021 we searched clinicaltrials.gov and trialsearch for ongoing maintenance trials with Letrozole, using the search terms ‘ovarian cancer’, ‘ER’, ‘endocrine therapy’ and ‘letrozole’, identifying one other trial (NCT04095364) for ovarian cancer patients), there is only one other clinical trial evaluating aromatase inhibitors as a first line monotherapy and in the maintenance setting of LGOC (NCT04095364) whereas it has been commonly evaluated in the relapsed setting [29].