Receptor 2-negative Advanced Breast Cancer Research Articles

Efficacy of Sacituzumab Govitecan in Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: A Comprehensive Systematic Review and Meta-analysis.

Breast cancer is the most diagnosed cancer in women, with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) being the predominant subtype. Sacituzumab govitecan (SG), a novel antibody-drug conjugate, has emerged as a promising treatment for metastatic HR+/HER2- breast cancer. This systematic review and meta-analysis aimed to evaluate its efficacy and safety. Adhering to "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" guidelines, a comprehensive search was conducted in PubMed, Scopus, and Cochrane databases up to December 2023. We included clinical trials and observational studies evaluating SG in patients with HR+/HER2- advanced breast cancer. The primary outcome was progression-free survival (PFS). In contrast, the secondary outcomes included overall survival, objective response rate, clinical benefit rate, duration of response (DOR), and adverse event profiles. Review Manager (Version 5.4) was used for the statistical analysis. Nine studies met the inclusion criteria for systematic review; 2 were suitable for meta-analysis. The pooled analysis showed a hazard ratio of 0.53 (95% CI: 0.34-0.83; P= 0.005; I2 = 86%) for PFSl and a hazard ratio of 0.63 (95% CI: 0.36-1.11; P= 0.11; I2 = 92%) for overall survival. The pooled analysis of the duration of response showed significant results with a standard mean difference = 0.22 (95% CI: 0.03-0.42; P = 0.02; I2 = 61%). SG demonstrates significant benefit in PFS and duration of response in patients of HR+/HER2- advanced breast cancer.

Impact of prior anticancer treatments on palbociclib (PAL) clinical outcomes in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2−) advanced breast cancer (ABC) in real-world settings.

1055 Background: Cyclin-dependent kinase 4/6 inhibitors (eg, PAL) combined with endocrine therapy (ET) is a standard of care for patients with HR+/HER2− ABC. The impact of prior anticancer treatments on clinical outcomes of patients with HR+/HER− ABC treated with palbociclib in routine care is not well known and was investigated in the POLARIS study. Methods: POLARIS is a prospective, observational, multicenter, real-world study in the US and Canada. Enrolled patients were adults (≥ 18 y) with HR+/HER2− ABC who received PAL + ET as standard of care. Real-world progression-free survival (rwPFS) and overall survival (OS) were described by prior treatment. Results: A total of 1250 patients were enrolled. Median age was 64 years (range, 22–97), 67.9% had recurrent disease, and 72.1% received PAL as first-line treatment (1LOT) vs 27.9% as ≥ 2LOT. Prior anticancer therapies (1LOT: adjuvant/neoadjuvant setting; ≥ 2LOT: metastatic setting) were received by 912 patients (73.0%), which included ET-alone (n=254), chemotherapy-alone (n=235), chemotherapy + ET (n=338) or other (n=85). The median follow-up duration was 35.7 months for rwPFS and 39.1 months for OS. In 1LOT, both rwPFS and OS were numerically shorter for patients who received prior chemotherapy (either alone or with ET) when compared with patients who received ET-alone or had no prior therapy (Table). In ≥ 2LOT, patients who received prior chemotherapy-alone or ET-alone had comparable rwPFS, which was numerically longer than for patients with prior chemotherapy + ET; OS was comparable regardless of prior treatment. Conclusions: Overall, patients with HR+/HER2− ABC with prior chemotherapy receipt tended to have shorter clinical benefit. Regardless of LOT, numerically longer rwPFS was achieved in patients who received prior ET-alone. In 1LOT, OS was longer in patients who received prior ET-alone while in ≥ 2LOT, OS was comparable across prior treatment subgroups. Small sample sizes of some ≥ 2LOT subgroups as well as observational nature of the study may limit interpretation. [Table: see text]

Real-world experience with CDK4/6 inhibitors in the first-line palliative setting for HR+/HER2- advanced breast cancer.

e13066 Background: CDK4/6 inhibitors paired with aromatase inhibitors (AIs) have redefined the first-line treatment for metastatic breast cancer, as evidenced by several pivotal trials. Although progression-free survival (PFS) has been consistent across these studies, notable differences in overall survival (OS) have been observed. Our study evaluates the real-world efficacy of palbociclib and ribociclib, in combination with AIs, for hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer at our institution. Methods: We retrospectively reviewed charts of adult patients with advanced metastatic breast cancer at a single academic center from January 1, 2015, to December 1, 2022. We extracted relevant clinical data to estimate the median PFS and OS associated with palbociclib and ribociclib. Results: Among 75 patients analyzed, the majority were female (98.7%) and postmenopausal (77.3%). Palbociclib was prescribed to 74.7%, while 52.0% presented with de novo stage IV disease. Those on ribociclib were significantly younger (median age 57.6 vs. 67.5 years; p = 0.013) and more likely premenopausal (42.1% vs. 5.4%; p < 0.001). Median PFS for palbociclib was 20.3 months (95% CI: 14.8-46.0), with an OS of 37.2 months (20.3 months to not reached). Median PFS and OS for ribociclib were not reached. The differences in PFS and OS between the drugs were not statistically significant (PFS log-rank p = 0.1; OS log-rank p = 0.2). Conclusions: Our real-world analysis suggests a non-significant trend towards improved PFS and OS for ribociclib over palbociclib when used with AIs for treating HR+/HER2- advanced breast cancer, potentially influenced by the younger age of patients on ribociclib. Further research with larger cohorts and extended follow-up is warranted to substantiate these observations.

Final Results of RIGHT Choice: Ribociclib Plus Endocrine Therapy Versus Combination Chemotherapy in Premenopausal Women With Clinically Aggressive Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer.

A head-to-head comparison of efficacy between a cyclin-dependent kinase 4/6 inhibitor plus endocrine therapy (ET) versus combination chemotherapy (CT) has never been reported in patients with clinically aggressive hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). In this open-label, multicenter, randomized phase II trial, pre/perimenopausal women with clinically aggressive HR+/HER2- ABC were randomly assigned 1:1 to first-line ribociclib (600 mg once daily; 3 weeks on, 1 week off) plus letrozole/anastrozole and goserelin or investigator's choice of combination CT (docetaxel plus capecitabine, paclitaxel plus gemcitabine, or capecitabine plus vinorelbine). The primary end point was progression-free survival (PFS). Among 222 patients randomly assigned to ribociclib plus ET (n = 112) or combination CT (n = 110), 150 (67.6%) had symptomatic visceral metastases, 41 (18.5%) had rapid disease progression per investigator's judgment, and 31 (14.0%) had symptomatic nonvisceral disease. Overall, 106 (47.7%) patients had investigator-assessed visceral crisis. The median follow-up time was 37.0 months. At data cutoff, 31.3% (ribociclib arm) and 15.5% (CT arm) of patients had completed study treatment and transitioned to post-trial access. The median PFS was 21.8 months (ribociclib plus ET; [95% CI, 17.4 to 26.7]) and 12.8 months (combination CT; [95% CI, 10.1 to 18.4); hazard ratio, 0.61 [95% CI, 0.43 to 0.87]; P = .003. The overall response rates and the median time to response in the ribociclib versus CT arms, respectively, were 66.1% and 61.8% and 4.9 months and 3.2 months (hazard ratio, 0.76 [95% CI, 0.55 to 1.06]). Lower rates of symptomatic adverse events were observed in the ribociclib versus CT arm. First-line ribociclib plus ET showed a significant PFS benefit, similar response rates, and better tolerability over combination CT in patients with clinically aggressive HR+/HER2- ABC.

Abstract PS12-09: Capivasertib plus cyclin-dependent kinase 4/6 inhibitor and fulvestrant in hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: updated Phase 1b analysis from CAPItello-292

Abstract Background AKT pathway activation is implicated in endocrine therapy (ET) and cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) resistance in patients (pts) with HR+/HER2– advanced breast cancer (ABC). In CAPItello-291, capivasertib (C, a potent inhibitor of all 3 AKT isoforms) + fulvestrant (F) significantly improved PFS versus placebo F in pts with aromatase inhibitor-resistant HR+/HER2– ABC. Simultaneous inhibition of AKT and CDK4/6 pathways may delay CDK4/6i resistance or re-sensitize tumors to ET plus CDK4/6i, leading to improved clinical outcomes. CAPItello-292 (NCT04862663) is an ongoing Phase 1b/3 study examining the efficacy and safety of C + CDK4/6i (palbociclib [P], ribociclib [R]) + F in HR+/HER2– ABC. The recommended Phase 3 dose (RP3D) of C+P+F has been determined (C 400 mg BID, 4 days on/3 days off, P 125 mg, F 500 mg). Here we report ongoing Phase 1b data on C+P+F and C+R+F. Methods: Phase 1b of CAPItello-292 uses a keyboard design (mTPI-2) with the following planned doses: C 200 mg, 320 mg, 400 mg; P 75 mg, 100 mg, 125 mg; R 200 mg, 400 mg, 600 mg; F is fixed at 500 mg every 28 days + loading dose on cycle 1 day 15. Starting doses for C+P+F were C 320 mg BID, 4 days on/3 days off, P 125 mg QD) for 21 days of each 28-day cycle. Starting doses for C+R+F (ongoing) are C 400 mg BID, 4 days on/3 days off, R 400 mg QD for 21 days of each 28-day cycle. Eligible pts have HR+/HER2− ABC and ≥1 prior ET in the advanced setting or disease recurrence within 12 months of completing (neo)adjuvant ET (HER2− defined as immunohistochemistry [IHC] 0, or 1-positive or IHC2-positive/in situ hybridization-negative). Prior use of CDK4/6i, selective estrogen receptor degraders, and chemotherapy is permitted in Phase 1b. Phase 1b primary objectives: assess safety/tolerability; confirm RP3D. Objective response and clinical benefit rates (24 weeks; RECIST v1.1) were also assessed. Results: At data cut-off (Apr 21, 2023), 40 pts (median age: 58.5 years [range 38–82]) who were heavily pre-treated (as follows: 82.5% [33/40] prior CDK4/6i; 47.5% [19/40] prior F; 70.0% [28/40] prior chemotherapy [median 1.5 lines]) were treated with C+P+F. No new dose-limiting toxicities (DLTs) were observed since determination of RP3D. The most frequent adverse events (AEs) occurring in >40% of pts were diarrhea (70.0% [28/40]; 1/28 grade [G] ≥3), neutropenia (55.0% [22/40]; 20/22 G≥3), fatigue, and nausea (both 42.5% [17/40]; all G1/2). Hyperglycemia occurred in 17.5% (7/40) pts (1/7 G3). No treatment-related deaths or new safety risks were identified. At the RP3D, the median (range) duration of exposure to C was 8.6 months (1.7–14.1); 5/8 pts with measurable disease at baseline had confirmed partial response (objective response rate: 62.5%, 95% confidence interval [CI] 24.5–91.5). Two additional pts had stable disease ≥7 weeks as a best objective response. At 24 weeks, the clinical benefit rate was 53.8% (7/13; 95% CI 25.1–80.8).Enrollment into C+R+F is ongoing: as of May 05, 2023, 8 pts had been dosed (6/8 pts had completed cycle 1). Based on clinical and safety review, the safety review committee has endorsed dose escalation to the highest dose level of R; no DLTs have been reported so far, although data are preliminary.Preliminary ctDNA analyses of pts treated with C+P/R+F will be presented. Conclusions: C+P+F was tolerable in heavily pre-treated pts with HR+/HER2– ABC at all dose levels; AEs were as expected, given the known safety profile of the individual treatments. Evidence of clinical activity has been observed in pts treated with the RP3D; data collection is ongoing. Preliminary safety analysis of C+R+F suggests no critical tolerability concerns; more pts and longer follow-up is required to characterize the safety of the combination. Updated data will be presented. Funding: AstraZeneca Capivasertib was discovered by AstraZeneca subsequent to a collaboration with Astex Therapeutics (and its collaboration with the Institute of Cancer Research and Cancer Research Technology Limited) Citation Format: Erika Hamilton, Patrick Neven, Barbara Pistilli, Muralidhar Beeram, Virginia Borges, Mario Campone, José Luiz Miranda Guimarães, Theodoros Foukakis, Annette Raskov Kodahl, Peter Lau, Elgene Lim, Iwona Ługowska, Greg Rychlik, Christopher Gresty, Claire Miller, Roberto Sommavilla, Dhivya Sudhan, Hope Rugo. Capivasertib plus cyclin-dependent kinase 4/6 inhibitor and fulvestrant in hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: updated Phase 1b analysis from CAPItello-292 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS12-09.

Abstract PO1-13-01: Safety profiles of Chinese breast cancer patients who received abemaciclib in MONARCH plus and monarchE study

Abstract Aim: Abemaciclib demonstrated efficacy with tolerable safety profile in Chinese patients (CN pts) with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (ABC) and high-risk early breast cancer (EBC). The overall safety profile of abemaciclib in Chinese ABC and EBC pts was consistent with overall population in the MONARCH plus and monarchE studies. To better understand the safety of abemaciclib in CN pts, beyond the previously reported most frequent adverse events (AEs), we report a comprehensive summary of other selected AEs in CN pts in the two trials. Methods: Study designs of MONARCH plus (NCT02763566) and monarchE (NCT03155997) studies were reported previously. To report detailed characteristics of a selected AE profile, including alanine aminotransferase increased, aspartate aminotransferase increased, blood creatinine increased, fatigue, nausea, and vomiting, data were pooled across all CN pts from these two phase 3 studies. The safety population was defined as all randomized patients receiving at least 1 dose of Abemaciclib or endocrine therapy. Data cutoff time is May 18, 2020 and July 1, 2022, respectively. Results: Among 6052 participants in the overall safety population, 875 CN pts (14.5%) were included (512/3100 abemaciclib, 363/2952 placebo). CN pts treated with abemaciclib indicated consistent AE profiles in combination with different endocrine therapies (aromatase inhibitors or Fulvestrant). Detailed characteristics of selected AEs are summarized in table. No deaths due to the selected AEs were reported in CN pts. Conclusion: The selected AEs of abemaciclib group were in low severity with limited grade 3-4 events. Those AEs were tolerable and generally manageable in CN pts in the MONARCH plus and monarchE trials. Citation Format: Zhimin Shao, Qingyuan Zhang, Quchang Ouyang, Qiang Liu, Jifeng Feng, Hui-Ping Li, Xiaojia Wang, Ning Liao, Liu Yang, Qinyi Zhu, Chenxi Qian, Zefei Jiang. Safety profiles of Chinese breast cancer patients who received abemaciclib in MONARCH plus and monarchE study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-13-01.

Abstract PO1-14-01: Clonal Architecture of circulating tumor DNA predicts Early Progression on Tamoxifen With or Without Palbociclib in Hormone Receptor-Positive Advanced Breast Cancer: NCCH1607/PATHWAY trial

Abstract Objective: Some patients with poor prognosis hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC) experience early disease progression on the combination of CDK4/6 inhibitors and endocrine therapy. We aimed to determine whether clonal architecture assessed by circulating tumor DNA (ctDNA) could identify patients at higher risk of early progression on tamoxifen therapy with or without palbociclib. Methods: PATHWAY trial is a randomized, placebo-controlled, Asian international, double-blind, phase 3 study evaluating palbociclib plus tamoxifen (PAL+TAM) versus placebo plus tamoxifen (PLB+TAM) in pre/perimenopausal and postmenopausal women with HR+/HER2- ABC (NCT03423199). The study was conducted as a Clinical Research Collaboration with the National Cancer Center Hospital as the regulatory study sponsor and Pfizer providing drug and financial support. The primary endpoint was investigator assessed progression-free survival (PFS). Genomic profiling by next-generation sequencing was an exploratory endpoint to characterize molecular alterations in ctDNA and correlate these with clinical outcomes. Plasma samples were collected at cycle 1-day 1 (pre-treatment) and cycle 2-day 15 and sequenced with the Guardant360 assay (Guardant Health). Patients were included if they had a minimum of 14 days of treatment in the first cycle. The variant allele frequency (VAF) was defined as number of mutant molecules at a specific nucleotide location over the total number of molecules present in the background at a specific given genomic location. We assessed the gene with highest VAF as the dominant clone allele frequency (DCAF). The association of changes in ctDNA alterations with PFS was evaluated to identify biomarkers of early progression. Results: Pre-treatment plasma was successfully sequenced in 177 of the 184 patients; 88 patients treated with PAL+TAM, and 89 with PLB+TAM. ctDNA was detected in 144 (81.4%) patients; the median number of genetic abnormalities was 2 (range, 0-19). PIK3CA, TP53, ERBB2, ESR1, AKT1, EGFR and PTEN were the genes with highest VAF as the dominant clone (24.3%, 11.9%, 4.5%, 4.5%, 3.4%, 3.4%, 3.4%, respectively). The median DCAF was 1.79 (range, 0.1-81.23); PAL+TAM, 2.53 (range, 0.1-63.5) and PLB+TAM, 1.65 (range, 0.08-81.23). Patients with ≥ 2 detectable genomic alterations and DCAF ≥ 1.8% had worse PFS (hazard ratio (HR) 1.93 [95% confidence interval (CI): 1.375 to 2.721], p = 0.0003 and HR 1.95 [95% CI: 1.345 to 2.834], p < 0.0001, respectively) compared to all other patients. In addition, we evaluated whether changes of clonal architecture in ctDNA at early treatment time point (ie. Cycle 2 Day 15) are associated with PFS. Patients with increased DCAF had worse PFS on both PAL+TAM (HR 2.80 [95% CI: 0.552 to 14.15], p = 0.04) and PLB+TAM (HR 2.02 [95% CI: 1.022 to 3.990], p = 0.01). All patients with high pretreatment DCAF (≥ 1.8%) and increase in DCAF progressed within 1 year (n=5, 2 patients treated with PAL+TAM, and 3 with PLB+TAM). Conclusion: Evaluation of clonal architecture in ctDNA could support identification of HR+/HER2- ABC patients with poorer prognosis, who may be at higher risk of early progression, regardless of CDK4/6 inhibitor use. Citation Format: Yoon-Sim Yap, Yuki Kojima, Akinobu Hamada, Hirofumi Mukai, Yen-Shen Lu, Joo Hyuk Sohn, Yoshiko Umeyama, Emi Noguchi, Kazuki Sudo, Tomomi Hata, Aya Kuchiba, Taro Shibata, Shigehiro Yagishita, Masayuki Yoshida, Shinji Kohsaka, Kouya Shiraishi, Kenichi Nakamura, Kenji Tamura, Kan Yonemori. Clonal Architecture of circulating tumor DNA predicts Early Progression on Tamoxifen With or Without Palbociclib in Hormone Receptor-Positive Advanced Breast Cancer: NCCH1607/PATHWAY trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-14-01.

Abstract PO3-04-10: Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy in Japanese patients with HR+/HER2- ABC in the first- or second-line setting: A multicenter observational study

Abstract Introduction Palbociclib (PAL), a selective, oral inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), plus (+) endocrine therapy (ET) is standard therapy for the treatment of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) and was launched in December 2017 in Japan. Efficacy and safety of PAL + ET was shown by randomized clinical studies, PALOMA-2 and PALOMA-3. Further, recent large real-world studies, P-REALITY/P-REALITY X, confirmed effectiveness of PAL+ aromatase inhibitor (AI) for HR+/HER2- ABC in routine United States clinical practice. However, there is limited real-world evidence (RWE) for PAL in Japan. To strengthen the RWE of PAL+ET for HR+/HER2- ABC treatment under different clinical practice and healthcare system, we examine the real-world effectiveness of PAL + ET as 1st line (1L) and 2nd line (2L) treatment for HR+/HER2- ABC in Japan. Methods In this multicenter, observational study, patients with HR+/HER2- ABC, who initiated PAL + ET from 15 December 2017 to 31 December 2020 were enrolled. To reduce selection bias, all patients who started PAL during the above period were listed and their eligibility confirmed. Eligible patients had 1) diagnosis of HR+/HER2- ABC; 2) received PAL + ET as 1L or 2L treatment; 3) at least 6 months of follow up from start of PAL or died within that period. The 1L treatment was defined as the first systemic therapy received for ABC regardless of recurrence timing if receiving adjuvant treatment. The subsequent treatment after 1L treatment was defined as a 2L treatment. The primary endpoint was real-world progression-free survival (rwPFS) defined as the time from PAL+ET start to physician-documented disease progression or death due to any cause, whichever occurs first. Secondary endpoints included overall survival (OS), and chemotherapy-free survival (CFS). Results were stratified by treatment line (ie. 1L or 2L). rwPFS, OS, and CFS were analyzed with the Kaplan-Meier method (NCT05399329). Results In this study, 677 patients were enrolled. Among them, 419 (62%) patients and 258 (38%) patients received PAL + ET as 1L and 2L, respectively. The median age was 59.0 (range 29-87) and 470 patients (69.8%) were postmenopausal. 49.0% patients had visceral involvement and 63.8% had a disease-free interval >24 months, defined as date of breast cancer surgery to the diagnosis date of recurrence, and 26.9% had de novo metastatic disease. The starting dose of PAL was 125 mg (89%), 100mg (9%), and 75mg (2%); dose reductions during the treatment period were required for 72% of patients. The most common ET combined with PAL was fulvestrant (FUL; 56.3% in 1L, 76.7% in 2L) followed by letrozole (LET; 37.9% in 1L, 16.3% in 2L). After a median follow-up of 36.2 months, the median rwPFS (95% CI) was 24.5 months (19.9-29.4) for 1L treatment and 14.5 months (10.2-18.3) for 2L treatment. Among the 604 patients initiating at 125 mg/day, the median rwPFS was 25.6 months (21.3-30.4) for 1L treatment and 14.3 months (9.7-18.3) for 2L treatment. Although median OS was not reached (NR) in 1L, median OS of 2L was 44.1 months (39.2 -NR). The 48-months OS rates for 1L and 2L treatment were 62.0% (55.4-67.9) and 48.4 % (40.4-55.9), respectively. The median CFS was 36.7 months (31.8-43.9) for 1L treatment and 23.8 months (20.5-27.3) for 2L treatment. Conclusions Our real-world data are consistent with findings form the PALOMA-2 and PALOMA-3 studies and those from RWE in routine United States clinical practice. FUL was the most commonly endocrine partner with PAL regardless of treatment lines. These observations add to the body of evidence supporting PAL effectiveness in clinical practice for Japanese ABC patients. Citation Format: Norikazu Masuda, Masaya Hattori, Tersuhiro Yoshinami, Takuho Okamura, Ken-ichi Watanabe, Takahiro Nakayama, Hiroko Masuda, Michiko Tsuneizumi, Daisuke Takabatake, Michiko Harao, Hiroshi Yoshino, Natsuko Mori, Hiroyuki Yasojima, Chiya Oshiro, Madoka Iwase, Miki Yamaguchi, Takafumi Sangai, Shinsuke Sasada, Takanori Ishida, Manabu Futamura, Nobuyoshi Kosaka, Yoshiyuki Shibasaki, Shigenori Nagai. Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy in Japanese patients with HR+/HER2- ABC in the first- or second-line setting: A multicenter observational study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-04-10.

Abstract PO2-04-10: Effect of Alpelisib Dose Modification for AE Management on Progression-Free Survival and Treatment Duration in SOLAR-1 and BYLieve Clinical Trials

Abstract Background: Alpelisib (ALP) is an α-selective phosphatidylinositol 3-kinase (PI3K) inhibitor and degrader approved with fulvestrant (FUL) for patients (pts) with phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-mutated, hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (ABC) following progression on/after endocrine therapy-based treatment (tx). Toxicity limited ALP exposure in some pts in the SOLAR-1 and BYLieve studies. On-target effects of PI3K inhibitors, including hyperglycemia, rash, and diarrhea, are among the most common adverse events (AEs) associated with ALP. During SOLAR-1, median onset times were 15 and 13 days for grade ≥3 hyperglycemia and rash and 46 days for grade 2/3 diarrhea. ALP dose modification can help manage AEs. We report efficacy of ALP + FUL as second-line (2L) tx in pts who underwent ALP dose reduction (DR). Methods: Pts with PIK3CA mutations from SOLAR-1 and BYLieve, treated with ALP + FUL in 2L, were included. Landmark (LM) analyses were performed at 1, 2, 3, 4, 5, and 6 mo after tx initiation to evaluate the association between DR status (yes, no) with progression-free survival (PFS) and duration of tx (DoT), respectively. Pts with PFS or exposure time less than each LM time point were excluded from each LM analysis; pts were then grouped by DR (yes, no) before each LM time point. Median PFS and DoT were obtained using a modified Kaplan-Meier method. Alternatively, Cox regression analysis was used to assess the effect of DR on PFS and DoT, where 2 time-dependent variables were included separately in the model as a covariate: 1) DR status, and 2) DR groups (300 to 250 mg [1 DR] vs no DR, 300 to 250 to 200 mg [2 DR] vs no DR). Association between AEs and DR was evaluated descriptively. A matched analysis of AEs will be presented. Results: In all, the analysis included 212 pts in 2L: 77 from SOLAR-1, and 95 and 40 from BYLieve Cohorts A and C, respectively. Of these pts, 92 (43.4%) had no DR and 120 (56.6%) had DRs: 70 (58.3%) had 1 DR, 43 (35.8%) had 2, and 7 (5.8%) had other types of DR. 25 of 92 pts (27.2%) with no DR and 40 of 120 pts (33.3%) with DR had ≥12-mo exposure to ALP. Hazard ratios (HRs) for PFS and DoT in DR status for the LM analysis are shown (Table). HRs (95% CI) for PFS from the time-dependent covariate analyses were 1.28 (0.94-1.74) with DR status as the covariate, and 1.24 (0.88-1.76) and 1.21 (0.79-1.84) with DR group (1 DR vs no DR, 2 DR vs no DR) as the covariate, respectively; for DoT, these were 1.34 (1.00-1.79) for DR status, and 1.30 (0.93-1.80) and 1.30 (0.87-1.93) for DR group, respectively. During the treatment period, the incidence rate for grade ≥3 AEs was the highest for pts with 2 DR and lowest for those with no DR. Similarly, incidence of AEs leading to DR or tx discontinuation was higher in pts with 2 DR than 1 DR. The post-DR incidence rate for grade ≥3 AE was similar for pts with 2 DR or 1 DR. A matched analysis will assess the relationship between DR group and AE. Conclusions: In this pooled analysis, regardless of if/when DR occurred, PFS was similar and DoT may be sustained with ALP + FUL. ALP DR can potentially reduce AEs, which may allow pts to remain on tx. Using DR as an AE management strategy may enable pts with PIK3CA-mutated, HR+, HER2− ABC to optimize tx duration and clinical benefit of ALP in the 2L. Landmark Analyses of PFS and Tx Duration by DR Group (Yes vs No; Pooled FAS) Citation Format: Hope Rugo, Alessandra Gennari, Stephen Chia, Dejan Juric, Neil Vasan, Sherko Küemmel, Patrick Neven, Florence Lerebours, Manuel Ruíz - Borrego, Pedram Razavi, Jyotika Singh, Yogesh Chattar, Murat Akdere, Eva Ciruelos. Effect of Alpelisib Dose Modification for AE Management on Progression-Free Survival and Treatment Duration in SOLAR-1 and BYLieve Clinical Trials [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-04-10.

Absolute lymphocyte count and neutrophil-to-lymphocyte ratio as predictors of CDK 4/6 inhibitor efficacy in advanced breast cancer.

Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) are the standard agents for treating patients with estrogen receptor-positive and human epidermal growth factor receptor 2-negative advanced breast cancer (ER + HER2 - ABC). However, markers predicting the outcomes of CDK4/6i treatment have yet to be identified. This study was a single-center retrospective cohort study. We retrospectively evaluated 101 patients with ER + HER2 - ABC receiving CDK4/6i in combination with endocrine therapy at Fukuyama City Hospital between November 2017 and July 2021. We investigated the clinical outcomes and the safety of CDK4/6i treatment, and the absolute lymphocyte count (ALC) and neutrophil-to-lymphocyte ratio (NLR) as predictive markers for CDK4/6i. We defined the cut-off values as 1000/μL for ALC and 3 for NLR, and divided into "low" and "high" groups, respectively. We evaluated 43 and 58 patients who received abemaciclib and palbociclib, respectively. Patients with high ALC and low NLR had significantly longer overall survival than those with low ALC and high NLR (high vs. low; ALC: HR 0.29; 95% CI 0.12-0.70; NLR: HR 2.94; 95% CI 1.21-7.13). There was no significant difference in efficacy between abemaciclib and palbociclib and both had good safety profiles. We demonstrated that ALC and NLR might predict the outcomes of CDK4/6i treatment in patients with ER + HER2 - ABC.

Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy (ET) in Japanese patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer in the first-line or second-line setting: an observational study

BackgroundA recent large real-world study conducted in the United States reported the effectiveness of palbociclib plus aromatase inhibitor in HR+/HER2− advanced breast cancer (ABC). However, local clinical practice and available medical treatment can vary between Japan and Western countries. Thus, it is important to investigate Japanese real-world data. This observational, multicenter study (NCT05399329) reports the interim analysis of effectiveness of palbociclib plus ET as first-line or second-line treatment for HR+/HER2− ABC by estimating real-world progression-free survival (rwPFS) and overall survival (OS) in Japanese routine clinical practice.MethodsReal-world clinical outcomes and treatment patterns of palbociclib plus ET were captured using a medical record review of patients diagnosed with HR+/HER2− ABC who had received palbociclib plus ET in the first-line or second-line treatment across 20 sites in Japan. The primary endpoint was rwPFS; secondary endpoints were OS, real-world overall response rate, real-world clinical benefit rate, and chemotherapy-free survival.ResultsOf the 677 eligible patients, 420 and 257 patients, respectively, had received palbociclib with ET as first-line and second-line treatments. Median rwPFS (95% confidence interval) was 24.5 months (19.9–29.4) for first-line and 14.5 months (10.2–19.0) for second-line treatment groups. Median OS was not reached in the first-line group and was 46.7 months (38.8-not estimated) for the second-line group. The 36-month OS rates for de novo metastasis, treatment-free interval (TFI) ≥ 12 months, and TFI < 12 months were 80.2% (69.1–87.7), 82.0% (70.7–89.3), and 66.0% (57.9–72.9), respectively.ConclusionThe addition of palbociclib to ET was effective for treating HR+/HER2− ABC in Japanese routine clinical practice.

Therapy for Hormone Receptor-Positive, Human Epidermal Growth Receptor 2-Negative Metastatic Breast Cancer Following Treatment Progression via CDK4/6 Inhibitors: A Literature Review.

Endocrine therapy (ET) with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) is currently the first-line standard treatment for most patients with hormone receptor-positive (HR+) and human epidermal growth receptor 2-negative (HER2-) metastatic or advanced breast cancer. However, the majority of tumors response to and eventually develop resistance to CDK4/6is. The mechanisms of resistance are poorly understood, and the optimal postprogression treatment regimens and their sequences continue to evolve in the rapidly changing treatment landscape. In this review, we generally summarize the mechanisms of resistance to CDK4/6is and ET, and describe the findings from clinical trials using small molecule inhibitors, antibody-drug conjugates and immunotherapy, providing insights into how these novel strategies may reverse treatment resistance, and discussing how some have not translated into clinical benefit. Finally, we provide rational treatment strategies based on the current emerging evidence.

Cost-effectiveness comparison of dalpiciclib and abemaciclib combined with an aromatase inhibitor as first-line treatment for HR+/HER2− advanced breast cancer

ABSTRACT Objectives CDK4/6 inhibitors dalpiciclib and abemaciclib have been approved by the Chinese National Medical Products Administration as first-line treatment for postmenopausal females with hormone receptor-positive (HR+) and human epidermal growth factor receptor-2 negative (HER2−) advanced breast cancer (ABC). We aimed to assess the cost-effectiveness of dalpiciclib plus letrozole/anastrozole (non-steroidal aromatase inhibitor [NSAI]) compared with abemaciclib plus NSAI as a first-line treatment for HR+/HER2− ABC in China. Methods We constructed a Markov model with three health states to evaluate health and economic outcomes of first-line treatment with dalpiciclib plus NSAI and abemaciclib plus NSAI for HR+/HER2− ABC. Efficacy data was obtained from MONARCH3 and DAWNA-2 trials. Quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs) were calculated. Results Compared with abemaciclib plus NSAI, dalpiciclib plus NSAI resulted in 4.27 additional QALYs, with an ICER of $14827.4/QALY. At a willingness-to-pay threshold of 3 times gross domestic product per capita in China for 2023 ($37721.5/QALY), the cost-effectiveness probability of dalpiciclib plus NSAI was 77.42%. Conclusions From the perspective of Chinese payers, dalpiciclib plus NSAI appears to be a cost-effective strategy compared with abemaciclib plus NSAI for the first-line treatment of patients with HR+/HER2− ABC in China. Clinical trial registration MONARCH3, www.clinicaltrials.gov, identifier is NCT02246621 and DAWNA-2, www.clinicaltrials.gov, identifier is NCT03966898.

A network meta-analysis of efficacy and safety for first-line and second/further-line therapies in postmenopausal women with hormone receptor-positive, HER2-negative, advanced breast cancer

BackgroundHormone receptor-positive/human epidermal growth factor receptor 2-negative (HR + /HER2 −) advanced breast cancer is a prevalent subtype among postmenopausal women. Despite the growing number of randomized clinical trials (RCTs) exploring this topic, the efficacy and safety of first-line and second/further-line treatments remain uncertain. Accordingly, our aim was to conduct a comprehensive evaluation of the efficacy and safety of these therapies through network meta-analysis.MethodsRCTs were identified by searching Pubmed, Embase, and major cancer conferences. The efficacy of interventions was assessed using the hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS), while safety was indicated by the incidence of any grade adverse events (AEs), grade 3–5 AEs, AEs leading to treatment discontinuation, and AEs leading to death. Both time-variant HRs fractional polynomial models and time-invariant HRs Cox-proportional hazards models were considered for handling time-to-event data. Safety indicators were analyzed using Bayesian network meta-analysis. Additionally, subgroup analyses were conducted based on patient characteristics.ResultsA total of 41 RCTs (first-line 17, second/further-lines 27) were included in the analysis. For first-line treatment, the addition of Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors to endocrine therapy significantly improved therapeutic efficacy in terms of both PFS and OS, demonstrating the best performance across all mechanisms. Specifically, the combination of Abemaciclib and Letrozole demonstrated the most favorable performance in terms of PFS, while Ribociclib plus Fulvestrant yielded the best outcomes in OS. Incorporating the immune checkpoint inhibitor Avelumab into the regimen with CDK4/6 inhibitors and selective estrogen receptor degraders significantly enhanced both PFS and OS in second-line or later treatments. Regarding safety, endocrine monotherapy performed well. Regarding safety, endocrine monotherapy performed well. There is mounting evidence suggesting that most CDK4/6 inhibitors may demonstrate poorer performance with respect to hematologic AEs. However, additional evidence is required to further substantiate these findings.ConclusionsCDK4/6 inhibitors, combined with endocrine therapy, are pivotal in first-line treatment due to their superior efficacy and manageable AEs. For second/further-line treatment, adding immune checkpoint inhibitors to CDK4/6 inhibitors plus endocrine therapy may produce promising results. However, to reduce the results’ uncertainty, further trials comparing these novel treatments are warranted.Trial registrationRegistration number: PROSPERO (CRD42022377431).

The value of oral selective estrogen receptor degraders in patients with HR-positive, HER2-negative advanced breast cancer after progression on ≥ 1 line of endocrine therapy: systematic review and meta-analysis

BackgroundCurrently, the value of oral selective estrogen receptor degraders (SERDs) for hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (aBC) after progression on ≥ 1 line of endocrine therapy (ET) remains controversial. We conducted a meta-analysis to evaluate progression-free survival (PFS) and safety benefits in several clinical trials.Materials and methodsCochrane Library, Embase, PubMed, and conference proceedings (SABCS, ASCO, ESMO, and ESMO Breast) were searched systematically and comprehensively. Random effects models or fixed effects models were used to assess pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for treatment with oral SERDs versus standard of care.ResultsA total of four studies involving 1,290 patients were included in our analysis. The hazard ratio (HR) of PFS showed that the oral SERD regimen was better than standard of care in patients with HR+/HER2- aBC after progression on ≥ 1 line of ET (HR: 0.75, 95% CI: 0.62-0.91, p = 0.004). In patients with ESR1 mutations, the oral SERD regimen provided better PFS than standard of care (HR: 0.58, 95% CI: 0.47-0.71, p < 0.00001). Regarding patients with disease progression following previous use of CDK4/6 inhibitors, PFS benefit was observed in oral SERD-treatment arms compared to standard of care (HR: 0.75, 95% CI: 0.64-0.87, p = 0.0002).ConclusionsThe oral SERD regimen provides a significant PFS benefit compared to standard-of-care ET in patients with HR+/HER2- aBC after progression on ≥ 1 line of ET. In particular, we recommend oral SERDs as a preferred choice for those patients with ESR1m, and it could be a potential replacement for fulvestrant. The oral SERD regimen is also beneficial after progression on CDK4/6 inhibitors combined with endocrine therapy.

First-line CDK4/6 inhibitor-based combinations for HR+/HER2- advanced breast cancer: A Bayesian network meta-analysis.

International guidelines recommend cyclin-dependent kinase 4/6 inhibitor (CDK4/6i)-based first-line therapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, direct drug comparisons are lacking. We aimed to identify the most effective and safe therapy through network meta-analysis (NMA). We searched PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and OpenGrey up to September 30, 2023. Eligible studies included randomized controlled trials (RCTs) assessing endocrine therapy alone or in combination with CDK4/6i as first-line endocrine treatment for HR+/HER2- ABC patients. The hazard ratios for progression-free survival (PFS) and overall survival (OS) and relative risks for objective response rate and adverse events (AEs) were available in selected trials. We performed a Bayesian NMA following PRISMA guidelines. Thirteen RCTs, involving 10 treatments, were included. Most studies were at low risk of bias. Regarding PFS, ribociclib+fulvestrant ranked first with a surface under the cumulative ranking curve (SUCRA) of 85.0%, followed by dalpiciclib+nonsteroidal aromatase inhibitor (NSAI) (SUCRA=78.9%). Considering OS, the top three ranked treatments were ribociclib+fulvestrant (SUCRA=94.1%), abemaciclib+NSAI (SUCRA=69.9%), and ribociclib+NSAI (SUCRA=68.5%). Out of four CDK4/6is, ribociclib minimized the grade 3/4 AEs, while dalpiciclib demonstrated the worst safety. Publication bias could not be ignored in our analyses, and the certainty of evidence was downgraded primarily due to imprecision. Ribociclib+fulvestrant probably represents the best option in a first-line setting. When combined with NSAI, dalpiciclib likely showed the best efficacy but the worst safety. Abemaciclib+NSAI and ribociclib+NSAI could also be promising treatments, while palbociclib presented inferiority. (PROSPERO Registration No. CRD42022370271).

Efficacy and safety of tucidinostat in patients with advanced hormone receptor-positive human epidermal growth factor receptor 2-negative breast cancer: real-world insights.

Tucidinostat, which is a subtype-selective histone deacetylase inhibitor, has been approved in China for the treatment of hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). However, existing evidence mainly stemmed from randomized controlled trials, and might have limitations in representing the complexities of clinical practice and diverse patient populations. Therefore, there is a need to explore the efficacy and optimal therapeutic modality for tucidinostat in real-world clinical settings. The objective of this real-world study was to analyze the clinical data of 47 patients with HR+/HER2- ABC who received tucidinostat treatment at West China Hospital, Sichuan University, between August 2020 and May 2023. The primary outcomes were progression-free survival (PFS) and clinical benefit rate [CBR; defined as partial response (PR) and stable disease (SD) for ≥6 months on clinical evaluation]. A total of 47 patients were included, and the median follow-up time was 18.20 months. The median line of tucidinostat therapy was 3 (range, 1-9). In all, 52.17% patients were treated with tucidinostat plus fulvestrant, while 38.30% were treated with tucidinostat plus aromatase inhibitors. Notably, 10.64% of the patients with rapidly progressing visceral metastases received tucidinostat plus endocrine therapy as maintenance treatment after achieving disease control with chemotherapy. The median PFS was 4.43 months [95% confidence interval (CI), 2.77-10.53], and the median overall survival was 19.57 months (95% CI, 12.83-not reached). The 6-month CBR for the overall population was 41.86%. Patients undergoing maintenance therapy demonstrated a significantly longer PFS than did those who did not receive it as maintenance therapy (14.13 vs. 3.93 months; P=0.01). Univariate Cox regression analysis showed that use of tucidinostat in lines 1-2, use of tucidinostat plus fulvestrant, presence of one metastatic site, and lack of brain metastasis were favorable factors for PFS. Thrombocytopenia was the most frequently reported adverse event, with an incidence rate of 31.91% at all grades and 14.89% at grade ≥3. Four (8.51%) patients discontinued the treatment. For patients with HR+/HER2- ABC, tucidinostat combination therapy offers certain survival benefits with controllable safety. Furthermore, compared with non-maintenance therapy, maintenance therapy after chemotherapy may have promising efficacy.

Is Alpelisib Plus Fulvestrant Cost-Effective for Treating PIK3CA-Mutation, HR+/HER2- Advanced Breast Cancer in the USA?

There is a considerable survival benefit of alpelisib in patients with PIK3CA-mutated, hormone receptor-positive and human epidermal growth factor receptor 2-negative advanced breast cancer (HR+/HER2- ABC), yet the financial burden may limit its use. Therefore, this study evaluated the cost-effectiveness of alpelisib plus fulvestrant in patients with PIK3CA-mutated, HR+/HER2- ABC in the USA. A Markov model was constructed to simulate the progression of PIK3CA-mutated, HR+/HER2- ABC. Efficacy and safety data were derived from the SOLAR-1 trial. A parametric survival model was used to explore the long-term effect. From a US payer perspective, only direct medical costs were considered. The cost data were estimated based on local pricing and relevant literature. The health outcomes were expressed in quality-adjusted life years (QALYs). Model stability was assessed using one-way sensitivity analysis and probability sensitivity analysis. Subgroup analyses were performed to explore cost-effectiveness outcomes for patients with different clinical characteristics. The QALY increased by 0.28 withalpelisib plus fulvestrant with an additional cost of $94,345.87 compared with placebo plus fulvestrant, leading to an incremental cost-effectiveness ratio (ICER) of $340,153.30/QALY gained. Sensitivity analyses suggested that the model is most sensitive to the price of alpelisib. At a willingness-to-pay (WTP) threshold of $150,000/QALY, alpelisib plus fulvestrant was cost effective when the cost of alpelisib was less than $71 per 300 mg (36.5 % of the original price), whereas this cost would be less than $168 per 300 mg (86.5 % of the original price) at a WTP threshold of $300,000/QALY. In addition, alpelisib + fulvestrant was not cost effective in all subgroups compared with placebo + fulvestrant at the WTP threshold of $150,000/QALY. In contrast, at the WTP threshold of $300,000/QALY, alpelisib + fulvestrant was cost effective in nearly all subgroups except for endocrine-sensitive patients. At current drug prices, alpelisib plus fulvestrant is not cost effective for patients with PIK3CA-mutated, HR+/HER2- ABC from a US payer perspective. Given the considerable progression-free survival (PFS) and overall survival (OS) benefits observed with alpelisib in this setting, further discussion and negotiation of the price of alpelisib are warranted to provide more favorable economic outcomes and thereby increase the value of the alpelisib plus fulvestrant regimen in patients.

Association of Neutrophil-to-Lymphocyte Ratio and Absolute Lymphocyte Count With Clinical Outcomes in Advanced Breast Cancer in the MONARCH 2 Trial.

Established prognostic factors for treatment response to cyclin-dependent kinases 4 and 6 inhibitors are currently lacking. We aimed to investigate the relationship of pretreatment neutrophil-to-lymphocyte ratio (NLR) and absolute lymphocyte count (ALC) to abemaciclib outcomes. This was a post hoc analysis of data from MONARCH 2, a phase III study of abemaciclib or placebo plus fulvestrant in hormone-receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer that progressed on endocrine therapy. Patients were divided into high and low categories based on baseline NLR (cutoff: 2.5) and ALC (cutoff: 1.5 × 109/L). The association of baseline NLR and ALC with progression-free survival (PFS) and overall survival (OS) was explored using Cox models and Kaplan-Meier estimates. Tumor response and safety were also examined. NLR and ALC data were available for 645 patients (abemaciclib: N = 426; placebo: N = 219). Low-baseline NLR or high-baseline ALC was consistently associated with positive PFS and OS trends; low-baseline NLR subgroups also showed trends for better response. The abemaciclib treatment effect against placebo was observed regardless of baseline NLR or ALC. Univariate analyses showed baseline NLR and ALC were prognostic of PFS and OS. Baseline NLR remained significant in the multivariate model (P < .0001). No unexpected differences in safety were observed by baseline NLR or ALC. Baseline NLR was independently prognostic of PFS and OS. Low-baseline NLR was associated with numerically better efficacy outcomes, but the benefit of adding abemaciclib to fulvestrant was similar irrespective of baseline NLR status.

167P A tumor immune microenvironment-based model for prediction of everolimus efficacy in premenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: Preliminary results from MIRACLE trial

167P A tumor immune microenvironment-based model for prediction of everolimus efficacy in premenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: Preliminary results from MIRACLE trial