Abstract OT2-02-01: A 'real world' experience of CDK4/6 inhibition with ribociclib and endocrine therapy in hormone receptor positive metastatic breast cancer in Australia

Abstract

Background: The combination of CDK 4/6 inhibition and endocrine therapy has emerged as the new first line standard of care treatment for patients with hormone receptor (HR) +ve metastatic breast cancer (MBC)1. Ribociclib plus letrozole has been shown to improve PFS (25.3 vs 16.0 months; log-rank P=9.63x10-8) compared to letrozole alone2. More recently, this benefit has also been demonstrated in pre- and peri-menopausal women in combination with ovarian suppression and tamoxifen or an aromatase inhibitor (AI), with an improved overall survival (40.9 months vs OS not reached; HR = 0.712; p=0.00973) in the MONALEESA-7 study3. Approximately 800 patients in Australia participated in the ribociclib medicine access program (MAP) between May 2017 and June 2018, prior to government funding. Beyond eligibility criteria for the program and clinician name, no patient data was initially captured, consistent with usual practice for MAPs, due to the multiple challenges related to ethics, data ownership, security and patient privacy. We have previously demonstrated the feasibility of successful data collection alongside MAPs4 which can yield benefits for clinicians, industry and the broader medical community. Based on this we plan to retrospectively collect data for patients treated as part of the Australian ribociclib MAP. Trial Design: This is a secondary data use, non-interventional study of patients in Australia who received treatment with the combination of an AI and ribociclib, obtained via a MAP, for HR+ HER2- MBC. The target sample size is 250 patients from ~15 sites. De-identified patient data will be retrieved from the patient’s medical records and entered on to an electronic case report form. Data collection is anticipated to commence in July 2019 with the final treatment and survival outcomes collected in late 2020, thus allowing for a minimum of 24 month follow up for all patients from the start date of treatment with ribociclib and AI (May 2017 - June 2018). Study Aims: The primary aim of the study is to describe real world clinical and tumour characteristics of patients with HR+ HER2-ve MBC in Australia who are recommended and received ribociclib in combination with an aromatase inhibitor in the first line setting. Details of adjuvant therapy received and the tolerability of the treatment combination including dose interruptions, dose reductions and significant adverse events of interest related to ribociclib will be assessed. Secondary aims include time to treatment progression and progression free survival for the ribociclib and AI combination, and to explore the disease course post progression, including clinician choice of subsequent lines of therapy in routine clinical practice. References: 1. Cardoso F, Senkus E, Costa A et al. 4th ESO-ESMO International Consensus Guidelines for Advanced Breast Cancer (ABC 4). Ann Oncol 2018;29:1634-1657. 2. Hortobagyi GN, Stemmer SM, Burris HA, Yap YS, Sonke GS, Paluch-Shimon S, et al. Updated results from MONALEESA-2, a phase III trial of first-line ribociclib plus letrozole versus placebo plus letrozole in hormone receptor-positive, HER2-negative advanced breast cancer. Ann Oncol 2018;29:1541-47. 3. Im SA, Lu YS, Bardia A, et al: Overall survival with ribociclib plus endocrine therapy in breast cancer. N Engl J Med. June 4, 2019 (early release online) 4. Lok SW, De Boer R, Cordwell C et al. Demonstrating the feasibility of collecting secondary, de-identified data on Australian patients receiving treatment as part of a Medicine Access Program. Intern Med J. 2019 Feb 28. Acknowledgement We thank Novartis for providing funding for this Research Collaboration. Citation Format: Sheau Wen Lok, Sally Baron-Hay, Elgene Lim, Robert Blum, Fran Boyle, Kerrie Clarke, Katharine Cuff, Michael Green, Laeeq Malik, Kelly Mok, Nick Murray, Louise Nott, Michelle Nottage, Ali Tafreshi, Daphne Tsoi, Belinda Yeo, Peter Gibbs, Richard De Boer. A 'real world' experience of CDK4/6 inhibition with ribociclib and endocrine therapy in hormone receptor positive metastatic breast cancer in Australia [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT2-02-01.

CDK4/6 Inhibitors in HR+/HER2- Advanced/metastatic Breast Cancer: A Systematic Literature Review of Real-World Evidence Studies

“…For palbociclib plus fulvestrant, dose reduction rates were 34.3% during first-line therapy [66], 33.3% during second-and subsequent-lines of therapy [47], and ranged from 11.1 [67] to 64.6% [45] across all lines of therapy. For first-line ribociclib plus AI, dose reductions occurred in 55% of patients [49]. The lowest proportion of patients with dose reductions was reported for abemaciclib plus ET in all lines, ranging from 0 to 5.7% [48].…”

“…For palbociclib plus fulvestrant, discontinuation rates ranged from 12.7 (the lowest reported incidence of treatment discontinuations) [67] to 19.9% [45] across all lines of therapy, and was higher (60%) in second-or subsequent-line treatment [47]. For ribociclib plus AI, 38.7% discontinued first-line treatment [49]. For abemaciclib (alone or in combination with ET), 45.8% discontinued across all lines of therapy [48] and 19% discontinued during secondor subsequent-line treatment (Table 3) [64].…”

“…Median PFS was also reported as not reached in two studies (one study each for abemaciclib [48] and ribociclib [49]). Only one RWE study reported a median PFS for either of the other CDK4/6i: abemaciclib (monotherapy or plus ET) as second-or subsequent-line therapy was associated with a median PFS of 7 months [50].…”

“…Six studies reported the median treatment duration for CDK4/6i (Supplementary Appendix 2) [49,52,[61][62][63][64]. The longest median treatment duration reported was 19 months for first-line ribociclib plus AI [49] and the shortest duration was 1.8 months for palbociclib plus AI across all lines of therapy (Table 3) [61]. Median treatment duration for first-line palbociclib plus AI ranged from 3.9 [61] to 15.8 months [52].…”

“…Treatment discontinuations for any reason (e.g., side effects, patient decision and completion of planned treatment) were reported in ten studies (Supplementary Appendix 2) [41,43,45,[47][48][49]51,61,64,67]. For palbociclib plus AI, discontinuation rates ranged from 22.9 [61] to 45.6% [57] during first-line therapy, and more broadly from 15.5 [67] to 79.4% (the highest reported incidence of treatment discontinuations) [41] across all lines of therapy (Table 3).…”