209P Efficacy and feasibility of long acting every three months goserelin for premenopausal breast cancer patients during COVID pandemic

Monthly Goserelin demonstrated safety and efficacy for treating pre-menopausal hormone receptor positive breast cancer patients in both adjuvant and metastatic settings. Although, every 3 months Goserelin 10.8 mg was already approved for the treatment of localized and metastatic prostatic carcinoma, it is not currently approved for use in breast cancer patients. The aim of this study is to evaluate safety and efficacy of goserelin 10.8 mg for breast cancer patients. Cohort A: Patients received 10.8 mg goserelin every 12 weeks. Cohort B: Retrospective review of patients' files who received monthly Goserelin. A daily oral dose of tamoxifen 20 mg or aromatase inhibitor were added. During the period between February 2020 and March 2021, 45 patients (cohort A) and 42 patients (cohort B) were included, median age were 37y and 35y respectively. Cohort A vs B: stage II (21.9% vs 21.4%), stage III (48.8% vs 52.4%) and stage IV (29.3% vs 26.2%). Luminal A (34.1% vs 30.9%), B1 (56.1% vs 57.1%) and B2 (9.8 vs 11.9%). Cohort A base line mean E2 level was 254.9 pg/dl. The median follow up duration was 21 months. The mean E2 levels for cohort A were 15.4 ng/dl, 10.8 ng/dl and 9.6 ng/dl at weeks 12, 24, and 36 respectively. All patients in both cohorts developed amenorrhea. For non-metastatic patients DFS was 86.2% for cohort A (n=29) and 87.1% for cohort B (n=31) without statistically significant difference (p=0.71). Metastatic patients PFS was 66.7% for cohort A (n= 12) and 63.6% for cohort B (n= 11) without statistically significant difference (p=0.88). All patients are alive, no serious adverse events (Grade 1 – II) were observed in both groups, hot flushes (65.8 % vs 66.7%), headache (36.6 % vs 40.5%), arthralgia (26.8% vs 28.5%), and hyperhidrosis (7.3 % vs 7.1%). Every 3 months goserelin is safe and effective as monthly formula with less frequent hospital visits that reduces exposure and transmission of infection especially during COVID pandemic.