A randomized, open-label, pre-surgical, window of opportunity study comparing the pharmacodynamic effects of the novel oral SERD AZD9496 with fulvestrant in patients with newly diagnosed ER+ HER2-primary breast cancer.

Outcome of adult ALL has improved considerably during the past decades by intensive chemotherapy, which still remains a challenge in older pts. This may be partly due to comorbidities. So far there are no standards to differentiate pts who will be able to tolerate even age-adapted chemotherapy (fit vs unfit). In addition, little is known about the prevalence of comorbidities. Clinical trials with new compounds often represent a selection of pts w/o comorbidities. There is also no generally accepted tool for comorbidity scoring. The goal of this analysis is to provide reference data for pre-existing comorbidities in a large set of adult ALL pts, to compare two different tools and to evaluate the impact on early death (ED) in older pts. The German Multicenter Study Group for Adult ALL (GMALL) has collected data from trials for younger (18-55 y) and older (>55 y) pts and from a prospective registry. Trials had very limited exclusion criteria and in the registry there are no exclusion criteria. The Charlson Comorbidity Index (CCI) was assessed in the GMALL Elderly trial, whereas the Sorror Score (HCT-CI) was used in trials for younger pts and in the registry. 879 pts had a documented HCT-CI score from GMALL 08/2013 trial (N=282;group 1) and 3 groups from the registry: >55 y but eligible for intensive therapy (N=56, group 2), > 55 y in GMALL Elderly protocol (N=505, group 3) and >55 y in GMALL Frail protocol (N=36; group 4) (Table 1). In addition the CCI was documented in 333 pts treated in the GMALL Elderly Trial. HCT-CI-Score: The most frequent comorbidities were infections (17%), prior malignancies (16%), diabetes (16%), cardiac (14%) and moderate pulmonary disease (12%), obesity (11%) and mild liver disease (10%). Arrhythmias (<1%, 5%, 12% and 22% resp. in groups 1, 2, 3, 4), cardiac disease (2%, 7%, 19% and 42% resp.), prior malignancies (2%, 11%, 25% and 22% resp.) and diabetes (4%, 16%, 22% and 22% resp.) increased with age. Infections (15%, 18%, 22% and 22% resp.) or obesity (9%, 7%, 11% and 14% resp.) were not strongly correlated to age. Comorbidity rates were lower in pts >55 y (group 2) considered eligible for intensive therapy (57%) compared to those considered for the Elderly protocol (76%) (group 3). The proportion of low risk (LR) scores decreased with age (54%, 43%, 25% and 8% resp.;p=.01), whereas high risk (HR) increased (18%, 25%, 50% and 59% resp; p=.01). CCI: The most frequent comorbidities were prior malignancy (14%), diabetes (25%) with (3%) or w/o (22%) end organ damage, cardiac (11%) and vascular disease (8%). The incidence of prior malignancy within the last 5 y was 7%. Risk classification was: LR (0) 51%, intermediate risk (IMR) (1-2) 42% and HR (≥3) 7%. HCT-CI vs CCI in pts >55 y: With HCT-CI the incidence of heart diseases (21% arrhythmias, cardiac disease or valve damage) was higher compared to CCI (9%), which differentiated better into cardiac failure (7%) and myocardial infarction (4%). Peripheral vascular disease (8% with CCI) is not assessed by HCT-CI. Liver disease was less frequent with CCI (1.5%) vs HCT-CI (14%) due to different definitions, whereas moderate pulmonary disease (12%) or infections (18%) are not assessed by CCI. The incidences of prior malignancies and diabetes were comparable. Of note, the overall incidence of distinct comorbidities e.g. cardiac was lower than the sum of subentities because some pts had several comorbidities. ED in pts >55 y: ED rates in pts >55 y in group 3 and in GMALL Elderly trial were comparable (13% vs 12% resp). In group 3 ED rates in risk groups (HCT-CI) were 7% vs 13% vs 15% (p>.05). In the GMALL Elderly trial ED in risk groups (CCI) were 9%, 12% and 35% (p=.05; p=.003 LR/IMR vs HR). Overall the analysis reveals a high incidence of comorbidities in older (57-92%) and even in younger pts (46%), which partly would represent contraindications in clinical trials with novel compounds; thus real world data in pts with comorbidities are required after marketing authorisation. HCT-CI and CCI have a different focus and shortcomings. For ALL pts a more specific score with different organ modules would be helpful. Comorbidity is significantly correlated to ED risk. CCI allows to identify a small HR group (7%) with a mortality of 35%. HCT-CI (24% of pts) and even more CCI (51% of pts) allow to identify LR groups with <10% early mortality. It will be of interest to analyse the impact of individual comorbidities on ED rate. Overall structured comorbidity assessment should be part of all clinical trials in ALL. Disclosures Viardot: Gilead Kite: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Amgen: Consultancy; BMS: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Fiedler:Teva: Other: support for meeting attendance; Gilead: Other: support for meeting attendance; Amgen: Other: support for meetíng attendance; Pfizer: Research Funding; Amgen: Research Funding; Amgen: Patents & Royalties; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; ARIAD/Incyte: Membership on an entity's Board of Directors or advisory committees, support for meeting attendance; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSO: Other: support for meeting attendance; JAZZ Pharmaceuticals: Other: support for meeting attendance; Daiichi Sankyo: Other: support for meeting attendance. Stelljes:JAZZ: Honoraria; MSD: Consultancy; Amgen: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Honoraria. Serve:Bayer: Research Funding. Goekbuget:Kite / Gilead: Consultancy; Celgene: Consultancy; Novartis: Consultancy, Other: Travel support, Research Funding; Pfizer: Consultancy, Other: Travel support, Research Funding; Amgen: Consultancy, Other: Travel support, Research Funding.

Background: Estrogen receptor positive (ER+) breast cancer is routinely treated with endocrine therapies targeting the ER axis. However, primary and secondary resistance ultimately limits the use of these agents. Fulvestrant (FULV) is the first-in-class selective ER degrader (SERD) clinically effective in patients with ER+ breast cancer, both naïve and resistant to tamoxifen and aromatase inhibitors. FULV has low oral bioavailability, and its dose-dependent pharmacodynamic (PD) activity and clinical efficacy is limited by the currently approved maximal feasible dose (MFD) of 500 mg, which is administered monthly as two intramuscular injections. AZD9496 is an orally bioavailable, nonsteroidal, selective and potent degrader and antagonist of ER in preclinical models. This pre-surgical, window of opportunity study (NCT03236974) compared PD changes and the PD/pharmacokinetic (PK) relationships of AZD9496 with FULV in patients with newly diagnosed ER+ HER2- breast cancer awaiting curative intent surgery.Methods: In this open-label, multicenter study, patients were randomized 1:1 to receive oral AZD9496 250 mg BID from Day 1 for 5-14 days or FULV 500 mg administered intramuscularly on Day 1 only. On-treatment image-guided core tumor biopsies were taken between Days 5 and 14. The primary objective was to compare the effects of AZD9496 and FULV on ER expression in tumor tissue using pre-dose biopsies as baseline. Secondary objectives were changes in progesterone receptor (PR) and Ki-67 biomarkers, AZD9496 and FULV plasma concentrations during treatment, and safety. Immunohistochemistry was used to determine ER and PR H-scores, and Ki-67 index, and treatment effects were compared using an analysis of covariance model. Blood samples for PK analysis were taken at on-treatment biopsy and 1-2 hours afterwards. Adverse events (AEs) were monitored from screening through to a follow-up visit 28 days after the last study dose.Results: Of the 49 women enrolled, 46 received treatment (AZD9496 n=22; FULV n=24) and of these, 35 paired biopsies were evaluable (AZD9496 n=15; FULV n=20). The least square mean estimate for the reduction in ER H-score after AZD9496 treatment was 24% (80% CI: 34.4, 14.3), and after FULV treatment was 36% (44.9, 27.7), with a least square mean difference between AZD9496 and FULV of 12% (p=0.86). AZD9496 was not superior to FULV in terms of ER modulation at the tested dose. AZD9496 also reduced PR H-scores and Ki-67 levels from baseline (by 33.3% and 39.9%, respectively). These effects were not statistically superior to FULV at the tested dose (PR: -68.7%, p=0.97; Ki 67: 75.4%, p=0.98).Plasma exposure of AZD9496 (AUC -40%, Cmax -25%) was lower than predicted based on PK data from the previous phase 1 study, whereas FULV exposure was consistent with historical data. No clear exposure-response relationship for plasma concentration at biopsy and PD markers for AZD9496 or FULV were observed.The median treatment duration of AZD9496 was 9.5 days (range: 6-15), and the relative dose intensity was 100% (range: 90-125); no patients discontinued AZD9496. AZD9496 and FULV were both well tolerated, and no new safety findings were identified. No grade ≥3 toxicities or serious AEs occurred. Conclusion: AZD9496 250 mg BID reduced ER, PR and Ki-67 expression, and as such, is the first pre surgical study to demonstrate an oral SERD impacting its key biological targets. These reductions were not superior to the FULV clinically approved dose, which performed as expected based on historical data. Pre-surgical studies represent an important method to test the proof of mechanism of novel SERDs early in clinical development. Citation Format: John FR Robertson, Abigail Evans, Stephan Henschen, Cliona Kirwan, Ali Jahan, Laura Kenny, J. Michael Dixon, Peter Schmid, Ashutosh Kothari, Omar Mohamed, Peter A Fasching, Kwok-Leung Cheung, Rachel Wuerstlein, Danielle Carroll, Teresa Klinowska, Justin PO Lindemann, Alexander MacDonald, Richard Mather, Rhiannon Maudsley, Michele Moschetta, Myria Nikolaou, Martine P Roudier, Tinnu Sarvotham, Gaia Schiavon, Diansong Zhou, Li Zhou, Nadia Harbeck. A pre-surgical, window of opportunity study comparing the novel oral SERD AZD9496 with fulvestrant in patients with newly diagnosed ER+ HER2- primary breast cancer [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 P6-04-01.

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