5025 Background: Letrozole is a potent oral aromatase inhibitor which rapidly suppresses circulating estrogen levels by 99% in postmenopausal women. By comparison with cytotoxic agents it is very well tolerated. We previously demonstrated an ‘endocrine sensitive’ subgroup of ovarian cancer patients with ER histoscore cutoff of ≥150 (Bowman et al, Clin Can Res 2002). Methods: This was a phase II study with a planned sample size of 33 patients. Eligible patients had relapsed EOC or primary peritoneal cancer with an ER histoscore of ≥150 and a rising CA125 that had progressed according to Rustin’s criteria. Patients were treated with letrozole 2.5mg daily until clinical or marker evidence of disease progression. The primary endpoint was response according to CA125 and RECIST criteria. Biomarker analysis by tissue microarray is also being performed. Results: 46 patients were accrued, 45 of whom were eligible. The median age was 61 (range 39–81). 24, 10 and 10 patients had received 1,2 and >2 previous lines of chemotherapy respectively. Of 43 patients evaluable for CA125 response, 7 (16%) had a response (decrease of >50%) and 16 (37%) patients had not progressed (doubling of CA125) following 12 weeks on treatment. In the CA125 responders, the nadir CA125 ranged from 0.7–49% of baseline (actual % of baseline: 0.7, 2.6, 11.1, 17.6, 23.6, 42.6, 49). Of the 7 responding patients, 5 had received only one previous line of chemotherapy. The time taken to achieve the nadir CA125 value ranged from 10 to 36 weeks, with a median of 13 weeks. Of 33 patients evaluable for radiological response, 3 (9%) had a PR and 14 (42%) had stable disease at 12 weeks. Overall, 11 patients (26%) had a PFS of >6 months and 2 patients (5%) had a PFS of ≥2 years. Conclusions: To our knowledge this is the first study of a hormonal agent in a selected ER +ve population of ovarian cancer patients. Promising efficacy of the agent is demonstrated in this population of pre-treated patients, many with a considerable bulk of disease. Given the median time of 13 weeks to response, we suggest that this strategy should be tested in ER+ve ovarian cancer patients in the adjuvant setting following first line chemotherapy No significant financial relationships to disclose.
A multicentre phase II study of AZD1775 plus chemotherapy in patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer