Abstract P6-18-38: Treatment patterns and sequences among pre-menopausal women with HR+/HER2- metastatic breast cancer: A chart review study

Background: Recently, a novel class of treatments, CDK4/6 inhibitors, has been approved, and is now recommended for pre-menopausal women with HR+/HER2- metastatic breast cancer (mBC). This study examined prevailing treatment patterns and sequencing among premenopausal women with mBC treated in clinical practice. Methods: Patient-level data were collected from patient charts in May 2018 from 30 oncologists, mostly from community practice, in the US. Treatment sequences and patterns were assessed for pre-menopausal women diagnosed with HR+/HER2- mBC between January 2015 and January 2017 (with a minimum of 1 year of follow-up). Results: Data were collected on 201 pre-menopausal women with HR+/HER2- mBC. In first-line therapy for mBC, 52.7% of the patients received a CDK4/6 inhibitor-based regimen, 23.4% received endocrine monotherapy, 20.9% received a chemotherapy-based regimen, and the remaining 3.0% received an everolimus-based regimen. The majority of patients who received a CDK4/6 inhibitor received it in combination with an AI (73.6%), fulvestrant (11.3%), or tamoxifen (6.6%). Approximately half of all patients (51.2%) received an ovarian suppression agent during first-line therapy. Overall, median time on treatment from Kaplan Meier (KM) analysis for first-line therapy was 16.1 months. Most common reason for discontinuing first line was disease progression or suboptimal response (79.0% of patients who discontinued); another common reason was the completion of the planned duration of therapy (12.6%). Among the 106 patients who received a CDK4/6 inhibitor in the first line, median time on treatment from KM analysis was 26.8 months. Main reason for CDK4/6 inhibitor discontinuation was disease progression or suboptimal response (90.2% of patients who discontinued). For the 109 patients for whom we observed a second-line therapy, treatment sequences are presented in Table 1. Median time on treatment for second and third line therapy was 9.6 and 7.8 months, respectively. Conclusion: Following the introduction of novel CDK4/6 inhibitor treatments in the mBC setting, we observed that approximately half of pre-menopausal patients received a CDK4/6-based regimen in the first line of therapy. Top 5 treatment sequences in pre-menopausal HR+/HER2- mBC patients (n=109)Treatment SequenceN(%)CDK4/6 - ET -> Everolimus - ET21(19.3%)Chemo -> Chemo16(14.7%)CDK4/6 - ET -> Chemo13(11.9%)ET -> CDK4/6 - ET13(11.9%)Chemo -> CDK4/6 - ET10(9.2%)ET: endocrine therapy; Chemo: chemotherapy; -> indicates a change to the next line of therapy. Percentages calculated among patients with at least 2 lines of therapy Citation Format: Dalal AA, Goldschmidt D, Romdhani H, Kelkar S, Guerin A, Wang H, Caria N, Sawhney A, O'Shaughnessy J. Treatment patterns and sequences among pre-menopausal women with HR+/HER2- metastatic breast cancer: A chart review study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-38.