Ribociclib Research Articles

Targeted delivery of liposomal Ribociclib to SLC7A5 transporters in breast cancer cells.

This study aimed to prepare SLC7A5 transporters targeted liposomes of Ribociclib (RB) by stear(o)yl conjugation of Phe, Asp, Glu amino acids to liposomes as targeting moieties. The liposomes were optimized for their formulations. Cell analysis on two cell lines of MCF-7 and NIH-3T3 were done including; cell viability test by MTT assay, cellular uptake, and cell cycle arrest by flow cytometry. The optimal liposomes showed the particle size of 123.6 ± 1.3 nm, drug loading efficiency and release efficiency of 83.87% ± 1.33% and 60.55% ± 0.46%, respectively. The RB loaded liposomes showed no hemolysis activity. Targeted liposomes increased cytotoxicity on MCF-7 cells more significantly than NIH-3T3 cells. Cell flow cytometry indicated that targeted liposomes uptake was superior to plain (non-targted) liposomes and free drug. Free drug and RB-loaded liposomes interrupted cell cycle in G1. However, amino acid-targeted liposomes arrested cells more than the free drug at this stage. Targeted liposomes reduced cell cycle with more interruption in the G2/M phase compared to the negative control.

57MO First-line (1L) ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in HR+/HER2− advanced breast cancer (ABC): A post hoc analysis of Asian and non-Asian patients (pts) from the phase II RIGHT choice trial

57MO First-line (1L) ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in HR+/HER2− advanced breast cancer (ABC): A post hoc analysis of Asian and non-Asian patients (pts) from the phase II RIGHT choice trial

VP3-2023: Health-related quality of life (HRQoL) in the phase III NATALEE study of adjuvant ribociclib (RIB) plus a nonsteroidal aromatase inhibitor (NSAI) vs NSAI alone in patients (pts) with HR+/HER2- early breast cancer (EBC)

VP3-2023: Health-related quality of life (HRQoL) in the phase III NATALEE study of adjuvant ribociclib (RIB) plus a nonsteroidal aromatase inhibitor (NSAI) vs NSAI alone in patients (pts) with HR+/HER2- early breast cancer (EBC)

456P Quality of life (QOL) analysis from the phase II RIGHT choice study of first-line ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in aggressive HR+/HER2− advanced breast cancer (ABC)

456P Quality of life (QOL) analysis from the phase II RIGHT choice study of first-line ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in aggressive HR+/HER2− advanced breast cancer (ABC)

409P Treatment of elderly patients (pts; > 75 years) with 1st-line ribociclib (RIB) + endocrine therapy (ET) or endocrine monotherapy in clinical routine: Real-world data from the RIBANNA study (5th interim analysis (IA))

409P Treatment of elderly patients (pts; > 75 years) with 1st-line ribociclib (RIB) + endocrine therapy (ET) or endocrine monotherapy in clinical routine: Real-world data from the RIBANNA study (5th interim analysis (IA))

402P First-line ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in aggressive HR+/HER2− advanced breast cancer (ABC): A subgroup analysis of patients (pts) with or without visceral crisis from the phase II RIGHT choice study

402P First-line ribociclib (RIB) + endocrine therapy (ET) vs combination chemotherapy (combo CT) in aggressive HR+/HER2− advanced breast cancer (ABC): A subgroup analysis of patients (pts) with or without visceral crisis from the phase II RIGHT choice study

441P Real-world efficacy of ribociclib (RIB) + aromatase inhibitor (AI)/fulvestrant (FUL) in subgroups of special interest: 5th interim analysis (IA) of the RIBANNA study

441P Real-world efficacy of ribociclib (RIB) + aromatase inhibitor (AI)/fulvestrant (FUL) in subgroups of special interest: 5th interim analysis (IA) of the RIBANNA study

LBA23 Invasive disease–free survival (iDFS) across key subgroups from the phase III NATALEE study of ribociclib (RIB) + a nonsteroidal aromatase inhibitor (NSAI) in patients (pts) with HR+/HER2- early breast cancer (EBC)

LBA23 Invasive disease–free survival (iDFS) across key subgroups from the phase III NATALEE study of ribociclib (RIB) + a nonsteroidal aromatase inhibitor (NSAI) in patients (pts) with HR+/HER2- early breast cancer (EBC)

411P Therapy management and safety of 1st-line ribociclib (RIB) + aromatase inhibitor (AI)/fulvestrant (FUL) in clinical routine: Real-world data from the RIBANNA study (5th interim analysis (IA))

411P Therapy management and safety of 1st-line ribociclib (RIB) + aromatase inhibitor (AI)/fulvestrant (FUL) in clinical routine: Real-world data from the RIBANNA study (5th interim analysis (IA))

Ribociclib (RIB) vs. palbociclib (PAL) in patients (pts) with hormone receptor-positive/HER2-negative/HER2-enriched (HR+/HER2-/HER2-E) advanced breast cancer (ABC): A head-to-head phase III study—HARMONIA SOLTI-2101/AFT-58.

TPS1125 Background: RIB and PAL are CDK4/6 inhibitors with demonstrated efficacy in terms of progression-free survival (PFS) and similar tolerability in pts with HR+/HER2- ABC when combined with endocrine therapy (ET). Only RIB has demonstrated a consistent, statistically significant, and clinically meaningful overall survival (OS) benefit across the MONALEESA (ML) phase III trials, while PALOMA trials failed to achieve similar outcome. Given effective treatments (Tx) may change underlying tumor biology (TB), it is hypothesized that RIB changes TB, enabling a better response to subsequent therapy and thus improving OS. RNA-based intrinsic subtyping reflects differences in TB and has strong prognostic and predictive value in HR+/HER2- ABC. Non-Luminal subtypes, as HER2-E and basal-like (BL), are relatively endocrine-resistant and have poorer prognosis than luminal. Tumors can switch subtypes over time to a more aggressive and less endocrine-responsive biology, which may also be reversed by effective Tx. A retrospective analysis of pooled data from ML 2/3/7 trials showed that HER2-E tumors had surprising benefit from RIB, while BL tumors did not. Pre/clinical data and indirect comparisons suggest that RIB may outperform PAL in HER2-E. Thus, choosing pts with HER2-E tumors as a means of a well defined TB with relative endocrine resistance provides the right setup for HARMONIA study to explore likely differential re-sensitization to endocrine therapy with RIB vs. PAL and ultimately testing which CDK4/6i prepares best for continued response and OS benefit. In addition, HARMONIA explores the value of earlier Tx with chemotherapy (paclitaxel) + anti PD-1 (tislelizumab) in pts with BL tumors to leverage learnings from treating ET-insensitive triple-negative BC. Methods: This is an international, multicenter, randomized, open-label, phase III study, using prospective pre-selection based on TB in pts with HR+/HER2- ABC, with HER2-E tumors (main cohort) and with BL tumors (exploratory cohort). HER2-E cohort will randomized pts 1:1 to RIB+ET (letrozole or fulvestrant) or PAL+ET. As per recent protocol amendment, BL cohort pts will be treated with paclitaxel plus tislelizumab, an anti PD-1 monoclonal antibody, pts may be offered to try RIB + ET first, and will remain eligible for paclitaxel + tislelizumab upon progression. Primary endpoint (EP): PFS per RECIST v1.1. Secondary EP: OS, PFS2, clinical benefit rate, duration and time to response, quality of life, and exploratory EP, including subtype switching between primary and metastatic tumor, and after trial Tx. Interim and primary EP analysis will be performed after 224 and 310 PFS events are observed (~80% power using one-sided 5% α). HARMONIA will recruit in Spain (55 sites), Portugal (5), and US (35) within SOLTI & AFT network. Clinical trial information: NCT05207709 .

Outcomes with first-line (1L) ribociclib (RIB) + endocrine therapy (ET) vs physician’s choice combination chemotherapy (combo CT) by age in pre/perimenopausal patients (pts) with aggressive HR+/HER2− advanced breast cancer (ABC): A subgroup analysis of the RIGHT Choice trial.

1063 Background: The progression-free survival (PFS; primary endpoint) results from the Phase II RIGHT Choice trial demonstrated a statistically significant median PFS (mPFS) benefit of ≈1 y with RIB + ET over combo CT (mPFS, 24.0 vs 12.3 mo; hazard ratio [HR], 0.54; 95% CI, 0.36-0.79; P = .0007) in pts with aggressive HR+/HER2− ABC. Younger pts with aggressive ABC have a worse prognosis, which impacts treatment (tx) decisions. Hence, a subgroup analysis of key efficacy endpoints from RIGHT Choice by age (< 40 vs ≥ 40 y) was undertaken. Methods: Pre/perimenopausal pts (aged 18-59 y) with HR+/HER2− ABC and no prior systemic therapy for ABC were randomized 1:1 to either RIB with letrozole/anastrozole + goserelin or investigator’s choice of combo CT (docetaxel + capecitabine, paclitaxel + gemcitabine, or capecitabine + vinorelbine). Pts in the trial had ABC not amenable to curative therapy and for which combo CT was clinically indicated by physician’s judgment (ie, symptomatic visceral metastases, rapid progression of disease or impending visceral compromise, or markedly symptomatic non-visceral disease). Results: In total, 70 pts were aged < 40 y and 152 were aged ≥ 40 y. In the combo CT arm, pts aged < 40 y fared worse and had a shorter mPFS, shorter median time to tx failure (mTTF), and higher 3-month tx failure rate (TFR) than pts aged ≥ 40 y. Pts aged < 40 y showed a significant PFS benefit with RIB + ET vs combo CT (mPFS, not reached [NR] vs 10.2 mo; HR, 0.38). This PFS benefit with RIB + ET over combo CT was also observed in pts aged ≥ 40 y (21.2 vs 16.0 mo; HR, 0.71). Regardless of age, the mTTF was longer and the 3-month TFR was lower in the RIB + ET arm than the combo CT arm. The median time to response (mTTR), overall response rate (ORR), and clinical benefit rate (CBR) were similar between the two tx arms in both age groups. Conclusions: This analysis demonstrated a clinically meaningful PFS benefit and improved secondary outcomes with 1L RIB + ET over combo CT along with similar treatment responses in both tx arms in pts aged < 40 y as well as in those ≥ 40 y with aggressive HR+/HER2− ABC. This analysis supports RIB + ET as a preferred tx option in this pt population, including younger pts aged < 40 y. Clinical trial information: NCT03839823 . [Table: see text]

Real-world efficacy of ribociclib (RIB) + aromatase inhibitor (AI)/fulvestrant (FUL), or endocrine monotherapy (ET), or chemotherapy (CT) as first-line (1L) treatment (tx) in elderly patients (pts; > 75 years) with hormone receptor–positive (HR+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC): Results of fifth interim analysis (IA) from RIBANNA.

e13050 Background: RIB+ET has demonstrated a statistically significant survival benefit across three phase 3 MONALEESA trials, irrespective of menopausal status, line of therapy, or combination partner. RIBANNA (CLEE011ADE03), a prospective, noninterventional study assessing the efficacy and safety of RIB+ET, or ET alone or CT in 1L setting in pre-, peri- and postmenopausal women with HR+, HER2– ABC is ongoing in Germany since October 2017. In this 5th IA from RIBANNA, efficacy, safety, and tolerability for exclusively elderly pts ( > 75 years) will be presented. Methods: Pts were included in accordance with the German tx guideline. The following analysis will be performed exclusively for pts > 75 years. Effectiveness analysis for PFS will be performed including propensity score matched (PSM) and Cox Proportional Hazards Regression (CPHR) analysis. Data for patient-reported outcomes (PRO) were collected at baseline and every 3 months until the end of treatment and will be evaluated using the Morisky Medication Adherence Scale (MMAS-8), questionnaires related to quality-of-life (EORTC QLQ-C30) and its breast cancer–specific module (EORTC QLQ-BR23) as well as the Hospital Anxiety and Depression Scale (HADS). Results: At data cutoff Sep 6, 2022, 2581 pts were enrolled in the study (RIB+AI/FUL, n = 2163; ET, n = 237; CT, n = 181). For pts > 75 years data from n = 434 (RIB+AI/FUL), n = 83 (ET) and n = 20 (CT) are available. In the overall population at baseline, the mean age (standard deviation [SD]) of patients was 65.5 (11.6), 70.8 (11.3), and 61.8 (11.6) years in the RIB + AI/FUL, ET, and CT cohorts, respectively. The unadjusted KM estimate for median PFS was 32.2 months (95% CI, 29.3–34.8) in the RIB + AI/FUL cohort, 35.2 months (95% CI, 23.9–44.2) in the ET cohort, and 16.7 months (95% CI, 9.9–17.5) in the CT cohort. Multivariate analysis showed that PFS was independently affected by several baseline parameter. After CPHR Analysis RIB + AI/FUL was associated with prolonged PFS compared with ET or CT. These results could be confirmed using PSM. The most frequent treatment-emergent adverse events (AEs) (all grade) in the RIB + AI/FUL cohort were neutropenia (25.8%), nausea (25.1%), fatigue (24.2%), and leukopenia (19.8%). Nausea and fatigue were the most common treatment-emergent AE (all grade) in both the CT and ET cohorts. Conclusions: RIBANNA study showed diverse population characteristics among pts who received RIB tx in a real-world setting. In the overall population Ribociclib showed superiority over ET and CT in the clinical routine, without new safety signals. Data for exclusively elderly pts ( > 75 years) will be presented.

Development and validation of a new bioanalytical method for quantification of CDK4/6 inhibitor in Spiked Human Plasma by HPLC-UV

Abstract A sensitive and accurate high performance liquid chromatography method utilizing ultraviolet/visible light detection (HPLC-UV) for the quantification of Ribociclib in Spiked Human Plasma by HPLC-UV was developed and validated. Ribociclib (RCB) and the internal standard (IS), Trifluridine, were first extracted from plasma samples by a simple Protein Precipitation extraction using Acetonitrile. Plasma concentration of RCB and internal standard were then analyzed by applying reversed phase chromatography using Orochem orosil C18 (4.6 mm × 250 mm, 5 μ) and elution with a isocratic mobile phase consisting of 10 mM phosphate buffer – Acetonitrile (60:40, v/v) adjusted to pH 3.0 at a flow rate of 1.0 ml/min. Detection of RCB and the IS was subsequently done at a wavelength of 260 nm. The limit of quantification was 10 ng/ml. The calibration curve was linear (R2>0.998) over the concentration range of 10-1000 ng/ml. For human plasma, the accuracy and precision were within ±15% and ≤15%, respectively, for all concentrations, except for the lower limit of quantification, where they were within ≤20%.

196P Efficacy and safety of first-line (1L) ribociclib (RIB) + letrozole (LET) in patients (pts) with de novo metastatic disease and late recurrence from (neo)adjuvant therapy (tx) in MONALEESA (ML)-2

196P Efficacy and safety of first-line (1L) ribociclib (RIB) + letrozole (LET) in patients (pts) with de novo metastatic disease and late recurrence from (neo)adjuvant therapy (tx) in MONALEESA (ML)-2

Abstract PD17-12: Primary efficacy and safety results from the AMALEE trial evaluating 600 mg vs 400 mg starting doses of first-line ribociclib in patients with HR+/HER2− advanced breast cancer

Abstract Background: In the Phase III MONALEESA (ML)-2, -3 and -7 trials, a 600 mg dose of ribociclib (RIB) demonstrated significant overall survival benefit in patients (pts) with HR+/HER2− advanced breast cancer (ABC) but was associated with QTcF (>480 ms, 3%-7%) and neutropenia (G3/4, 57%-64%) adverse events (AEs) which were managed by dose reductions. The Phase II AMALEE study was performed as a postmarketing commitment to assess whether reducing the starting dose of RIB from the recommended dose (3 wk on, 1 wk off) of 600 mg/day to 400 mg/day decreases QTcF prolongation without compromising the efficacy of first-line RIB in pts with HR+/HER2− ABC. Here, we present efficacy and safety results from the primary analysis of AMALEE. Methods: AMALEE is a randomized Phase II open-label study including pre- and postmenopausal pts with HR+/HER2− ABC with no prior therapy for ABC. Pts received RIB 400 mg + nonsteroidal aromatase inhibitor (NSAI) or RIB 600 mg + NSAI. The primary endpoint is to determine whether overall response rate (ORR) in the 400 mg arm is noninferior to the 600 mg arm. The key secondary endpoint is QTcF prolongation at cycle 1, day 15 (C1D15) 2 hours post dose. Additional endpoints included safety, progression-free survival (PFS), duration of response (DOR), time to response (TTR), and pharmacokinetics. Results: A total of 376 pts were randomized 1:1 to receive RIB at either 400 mg or 600 mg doses. Baseline (BL) characteristics and prior antineoplastic therapy were balanced across treatment (tx) arms. At the time of the data cutoff (June 11, 2021), median follow-up was 14.9 mo (min, 6.1; max, 23.8), and all pts had been treated for ≥6 months from randomization or had discontinued study tx. ORR for RIB was 41.5% (95% CI, 34.4-48.7) with 400 mg vs 45.3% (95% CI, 38.1-52.6) with 600 mg (ORR ratio for RIB 400 mg vs 600 mg, 0.921 [90% CI, 0.757-1.121]). The lower 90% CI boundary did not meet the prespecified noninferiority (NI) margin of 0.814. Results for ORR by subgroups were consistent with the overall analysis set. RIB plasma exposure was lower at 400 mg than 600 mg; the geometric mean Cmax and AUC0-24h at C1D15 were approximately 28% and 43% lower in the 400 mg than the 600 mg arm (Cmax 1080 vs 1500 ng/mL and AUC0-24h 16400 vs 28600 ng × h/mL). This study met the key secondary endpoint, change in QTcF at C1D15 in the RIB 400 mg group with a 90% CI upper boundary of < 20 ms. Mean change in QTcF from BL to C1D15 2 hours post dose was lower in the 400 mg (12.5 ms, 90% CI, 10.9-14.1) than the 600 mg arm (19.7 ms, 90% CI, 17.4-22.0). QTcF ≥501 ms occurred in 1.6% of pts in the 400 mg arm vs 0.5% in the 600 mg arm. Rates of G3/4 neutropenia were lower in the 400 mg (31.4%) than the 600 mg arm (46.3%). Other safety results were consistent with those previously reported for RIB in the ML trials. Median duration of exposure to RIB was 8.0 mo (min, 0.1; max, 23.7) in the 400 mg arm vs 8.8 mo (min, 0.5; max, 20.8) in the 600 mg arm. Dose reductions of RIB were more frequent in the 600 mg group with 30.5% vs 13.8% of pts requiring 1 dose reduction in the 600 mg and 400 mg groups, respectively. Dose reductions were primarily attributable to AEs, with neutropenia being the most frequently reported AE requiring a dose modification. Rates of discontinuation due to AEs were similar in the 400 mg vs 600 mg arms (8.5% vs 9.6%). PFS, DOR, and TTR data are currently immature. Conclusions: RIB at the 400 mg dose shows a better safety profile vs 600 mg in terms of key AEs that are RIB concentration dependent (neutropenia and QTcF prolongation). ORR was 3.8% lower with 400 mg than 600 mg. The lower 90% CI boundary of the ORR ratio did not meet the NI margin, thus this study was unable to demonstrate statistical NI of the 400 mg vs 600 mg dose of RIB using ORR as the endpoint. Updated results with additional follow-up and the clinically relevant endpoint PFS will be presented at the congress. Citation Format: Fatima Cardoso, William Jacot, Sherko Küemmel, Sudeep Gupta, Rama Balaraman, Liudmila Lebedeva, Yan Ji, Aparna Lakshmanan, Khalid Amin, Zheng Li, Joseph Sparano. Primary efficacy and safety results from the AMALEE trial evaluating 600 mg vs 400 mg starting doses of first-line ribociclib in patients with HR+/HER2− advanced breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD17-12.

Abstract P4-01-42: Pooled analysis of post-progression treatments after first-line ribociclib + endocrine therapy in patients with HR+/HER2− advanced breast cancer in the MONALEESA-2, -3, and -7 studies

Abstract Background: The MONALEESA (ML) studies showed significant PFS & OS benefits for 1L ribociclib (RIB) + endocrine therapy (ET) in patients (pts) with pre/peri & postmenopausal advanced breast cancer. The benefit of RIB beyond study treatment (tx) was also observed, with improvements in PFS2 & delays in time to 1st subsequent chemotherapy (CT). While there is currently no preferred tx for the next line post-progression on a CDK4/6 inhibitor (CDK4/6i), except alpelisib in pts with a PIK3CA mutation, guidelines encourage multiple lines of ET or ET-based therapies before switching to CT (except for visceral crisis). This pooled exploratory analysis of the ML studies examined outcomes of various tx strategies post progression on RIB + ET. Methods: Data from pts receiving 1L therapy in ML-2, -3, & -7 (NSAI cohort only & excluding pts with early relapse [≤ 12 mo after end of (neo)adjuvant ET] whose prognosis is closer to that of 2L pts) were pooled & pts receiving 1st subsequent therapies after progression were analyzed. Three groups of subsequent therapies were assessed: ET only, CT, & targeted therapy. Subsequent CT comprises CT +/- any other therapy; targeted therapy includes CDK4/6i, mTORi, PI3Ki, AKTi, etc, +/- ET. Subsequent CT & targeted therapy groups are mutually exclusive. Median duration of study tx, 1st subsequent therapy, & OS (from randomization to death) were analyzed by KM methods. Weighted Cox regressions were performed using inversed propensity scoring matching method (inverse probability tx weighting [IPTW]) to ensure compatible pt characteristics between tx arms. These are not randomized comparisons; only baseline characteristics were used for the estimation of propensity scores in the IPTW, imbalance of prognostic factors at progression may exist. Results: Median follow-up time was 74 mo. 461 pts treated with RIB (81%) & 440 (86%) with PBO discontinued study tx & received a subsequent therapy. In the RIB arms, the most common 1st subsequent therapies were ET only (40%), CT (29%), combination with targeted therapy (28%), & other (4%); for the PBO arms, 34% received CT as a 1st subsequent therapy & 31% each received ET only or combination with targeted therapy (5% received other). In 14% & 20% of pts in the RIB & PBO arms, the 1st subsequent therapy was a CDK4/6i, of these 31% & 12% were RIB. In general, regardless of type of 1st subsequent therapy, the duration of both the study tx & the 1st subsequent therapy was longer for pts treated with RIB vs PBO (Table). In both RIB & PBO arms, pts who received subsequent CT had the shortest duration on study tx, whereas those who received subsequent targeted therapy combination had the longest. Among pts on 1L RIB + ET, after matching pre-randomization baseline characteristics, subsequent CDK4/6i use was associated with the longest mOS (84 [84-NE] mo), followed by ET only (60 [51-68] mo), then a non-CDK4/6i targeted therapy (52 [43-72] mo); post-progression CT was associated with the shortest mOS (37 [32-48] mo). Conclusions: This large, pooled analysis of the ML studies shows that, in general, duration of any subsequent therapy was numerically longer post-1L RIB + ET vs PBO + ET, & subsequent CT was used less frequently for pts on RIB vs PBO. Both findings confirm that upfront tx with RIB does not worsen pt outcomes. This trend in enhancement of outcomes of subsequent therapies seen with 1L RIB suggests a post-tx effect that merits further exploration. Citation Format: Erika Hamilton, Laura M. Spring, Peter A. Fasching, Sandra Franco, Richard H DeBoer, Javier Cortés, Kevin Kalinsky, Dejan Juric, Aditya Bardia, Sina Haftchenary, Agnes Lteif, Juan Pablo Zarate, Liyi Cen, Patrick Neven. Pooled analysis of post-progression treatments after first-line ribociclib + endocrine therapy in patients with HR+/HER2− advanced breast cancer in the MONALEESA-2, -3, and -7 studies [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-01-42.

Abstract P4-01-01: RIBANNA 5th interim analysis: Matched-pair analysis of progression-free survival (PFS) across treatment cohorts and comparison of frontline ribociclib + endocrine therapy PFS data from RIBANNA vs MONALEESA trials, in HR+, HER2– ABC

Abstract Background: Ribociclib (RIB) plus endocrine therapy (ET) has demonstrated a statistically significant survival benefit across the three phase 3 MONALEESA (ML) trials, irrespective of menopausal status, line of therapy, or combination partner. RIBANNA (CLEE011ADE03), a prospective, noninterventional study assessing the efficacy and safety of RIB + ET, or ET monotherapy or chemotherapy (CT) in first-line (1L) setting in pre-, peri- and postmenopausal patients (pts) with hormone receptor–positive (HR+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC) is ongoing in Germany since October 2017 to gain insights into real-world scenario. In the 5th interim analysis (IA) from RIBANNA, a matched-pair analysis of 1L PFS data from the three treatment cohorts and comparison of 1L PFS data on RIB + ET from RIBANNA versus (vs) ML trials will be performed. Methods: Pre-, peri- and postmenopausal women receiving RIB + ET, ET monotherapy, or CT as 1L treatments for HR+, HER2– ABC, in accordance with German treatment guidelines, were included. Propensity score matched (PSM) analysis of PFS data from the 3 treatment cohorts will be conducted to reduce the bias due to confounding variables. In addition to safety analyses, comparison of 1L PFS data on RIB + ET from RIBANNA vs ML trials will be performed. Results: By the cutoff date of the 4th IA (October 11, 2021), data were available for 2187 pts, including 1849 (83.0%), 193 (78.1%), and 145 (73.6%) pts from the RIB + ET, ET monotherapy, and CT cohorts in 1L setting, respectively (Table 1). Of these 2187 pts, 1111 postmenopausal pts received 1L RIB + letrozole; 357 postmenopausal pts received 1L RIB + fulvestrant, and 158 pre- and perimenopausal pts received 1L RIB + anastrazole/letrozole. The unadjusted Kaplan–Meïer estimate for median PFS was 31.7 months (95% confidence interval [CI], 28.5–36.2) in the RIB + ET cohort, 25.7 months (95% CI, 18.0–not reached) in the ET monotherapy cohort, and 15.3 months (95% CI, 9.5–17.5) in the CT cohort. The most frequent treatment-emergent adverse events (grade 3 or 4) in the RIB + ET and ET monotherapy cohorts were neutropenia (14.8% and 6.6%, respectively) while that in CT cohort was general physical health deterioration (9.1%). Conclusions: In RIBANNA, a diverse pt population is being analyzed in a real-world setting; treatment with RIB + ET has been observed to be well adopted. The 5th IA is planned in October 2022 and data will be presented in SABCS 2022, which will include PSM analysis to compare 1L PFS data across treatment cohorts as well as comparison of 1L PFS data on RIB + ET from RIBANNA vs ML trials. The safety profile of RIB was found to be similar to those observed in ML trials. Table 1. Patient demographics and baseline clinical characteristics from the 4th IA. Citation Format: Christian Jackisch, Cosima Brucker, Thomas Decker, Anne Engel, Peter A. Fasching, Thomas Göhler, Jan Janssen, Andreas Köhler, Kerstin Lüdtke-Heckenkamp, Diana Lüftner, Marion van Mackelenbergh, Frederik Marmé, Arnd Nusch, Beate Rautenberg, Toralf Reimer, Marcus Schmidt, Rudolf Weide, Pauline Wimberger, Christian Roos, Achim Wöckel. RIBANNA 5th interim analysis: Matched-pair analysis of progression-free survival (PFS) across treatment cohorts and comparison of frontline ribociclib + endocrine therapy PFS data from RIBANNA vs MONALEESA trials, in HR+, HER2– ABC [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-01-01.

Abstract P5-02-14: Identification of mechanisms of acquired resistance to ribociclib plus endocrine therapy using baseline and end-of-treatment circulating tumor DNA samples in the MONALEESA-2, -3, and -7 trials

Abstract Background: Genetic alterations that contribute to resistance to therapy may be acquired during treatment (tx) for hormone receptor−positive/human epidermal growth factor receptor−negative (HR+/HER2−) advanced breast cancer (ABC). A previous pooled analysis of circulating tumor DNA (ctDNA) in MONALEESA (ML)-2, -3, and -7 identified potential predictive biomarkers for response and resistance to ribociclib (RIB) at baseline (BL). Here, we describe an analysis of paired BL and end of treatment (EOT) samples from ML-2, -3, and -7 to identify acquired mechanisms that may impact resistance to RIB + endocrine therapy (ET) vs placebo (PBO) + ET. Methods: ML-2 (NCT01958021), ML-3 (NCT02422615), and ML-7 (NCT02278120) evaluated efficacy and safety of RIB + ET vs PBO + ET in pre- and postmenopausal patients (pts) with HR+/HER2− ABC treated in first-line (1L) and second-line (2L) settings. Plasma samples were collected at cycle 1 day 1 (C1D1; prior to first therapy exposure) and at EOT (± 28 days of recorded progression). ctDNA was sequenced using a targeted next-generation sequencing panel of ≈550 genes. Genes with an alteration frequency of >5% at EOT, regardless of their frequency at BL, were included. Tumor mutational burden (TMB) was assessed by tx arm; a TMB cutoff of 10 mutations/MB was used to categorize pts as TMB high vs low. To assess differences in the presence of alterations, a McNemar test was performed on paired samples and adjusted (adj) for multiple testing using the false discovery rate (FDR). A Bayesian mixed effects model was used to account for ctDNA fraction and trial and to test for tx-specific resistance by including a tx × visit interaction term. Results: A total of 905 paired samples from ML-2, -3, and -7 were included in this analysis, 441 and 464 samples from pts treated with RIB + ET and PBO + ET, respectively. Overall, 17 genes had an alteration frequency of >5% at EOT. The ctDNA fraction was higher at EOT vs C1D1 in both the RIB (P=.037) and PBO (P=.033) arms. The frequency of alterations in RB1 (10.4% vs 2.0%), ATM (11.3% vs 8.4%), FAT1 (4.8% vs 3.0%), and FAT3 (5.0% vs 2.5%) was higher at EOT vs C1D1 in the RIB arm (FDR-adj P<.10). Alterations in ESR1 were also higher at EOT vs C1D1 in both the RIB (26.3% vs 9.1%) and PBO arms (28.9% vs 5.4%) (FDR-adj P<.0001). Conversely, alterations in GATA3 were higher at EOT in the PBO arm (FDR-adj P=.11). These results were consistent after adjusting for ctDNA fraction. The most common ESR1 mutations were D538G, Y537S/N/C/D, E380Q, and L536H/P/R. Tx × visit interaction effects were observed for RB1 in the RIB arm and GATA3 in the PBO arm, suggesting tx-specific resistance. A tx × visit interaction for ESR1 was also observed, suggesting a larger relative increase in ESR1 mutations with PBO vs RIB. The percentage of pts with high TMB (>10) at EOT increased from 1.1% to 5.7% in the RIB arm and from 1.7% to 3% in the PBO arm. After accounting for ctDNA fraction and trial, a larger numerical increase in TMB was observed for RIB (odds ratio [OR], 9.0; 95% CI, 2.9-32.7) vs PBO (OR, 2.1; 95% CI, 0.7-6.5); however, the model did not support a differential tx effect. Conclusions: This comprehensive analysis of pooled samples from ML-2, -3, and -7 identified acquired gene alterations in pts with HR+/HER2− ABC treated with 1L or 2L RIB + ET or PBO + ET. The frequency of several genes known to contribute to resistance (ESR1, RB1, ATM, FAT1, and FAT3) was higher at EOT vs C1D1 in pts treated with RIB + ET, while ESR1 and GATA3 alterations were higher at EOT vs C1D1 in pts treated with PBO + ET. This paired dataset of BL and EOT samples from pts with HR+/HER2− ABC treated with a CDK4/6 inhibitor and ET is the largest to date and could be used to validate and confirm acquired resistance mechanisms with low alteration frequency. Citation Format: Fabrice Andre, Nadia Solovieff, Faye Su, Aditya Bardia, Patrick Neven, Yoon-Sim Yap, Debu Tripathy, Yen-Shen Lu, Dennis Slamon, Stephen K. Chia, Mukta Joshi, Arunava Chakravartty, Agnes Lteif, Tetiana Taran, Carlos Arteaga. Identification of mechanisms of acquired resistance to ribociclib plus endocrine therapy using baseline and end-of-treatment circulating tumor DNA samples in the MONALEESA-2, -3, and -7 trials [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-14.

Abstract GS1-10: Primary results from the randomized Phase II RIGHT Choice trial of premenopausal patients with aggressive HR+/HER2− advanced breast cancer treated with ribociclib + endocrine therapy vs physician’s choice combination chemotherapy

Abstract Background: Combination chemotherapy (CT) remains a standard of care in advanced breast cancer (ABC) with aggressive disease features (rapidly progressing or highly symptomatic disease, including life-threatening visceral crisis). To date, no data have been published on a head-to-head comparison of CDK4/6 inhibitor (CDK4/6i) + endocrine therapy (ET) vs combination CT in this patient (pt) population. RIGHT Choice, a randomized, open-label, multi-national, Phase II trial, investigated the efficacy and safety of first-line ribociclib (RIB) + ET vs combination CT in pre/perimenopausal pts with HR+/HER2− ABC with aggressive disease (where combination CT is clinically indicated by physician’s judgment). Here we report the results of the primary endpoint of progression-free survival (PFS) and key secondary endpoints from this study. Methods: Pre/perimenopausal pts with HR+/HER2− ABC (>10% estrogen receptor–positive [ER+]) and no prior systemic therapy for ABC were randomized 1:1 to receive either RIB (600 mg daily, 3 weeks on/1 week off) with letrozole/anastrozole + goserelin or investigator’s choice of CT (docetaxel + capecitabine, paclitaxel + gemcitabine, or capecitabine + vinorelbine). Randomization was stratified by presence of liver metastases and whether the disease-free interval (duration from date of complete tumor resection for primary breast cancer lesion to the date of documented disease recurrence) was less than two years. Pts included in the trial had ABC not amenable to curative therapy for which combination CT was clinically indicated by physician’s judgment (i.e., symptomatic visceral metastases, rapid progression of disease or impending visceral compromise, or markedly symptomatic non-visceral disease). Median PFS (mPFS) and median time to treatment failure (mTTF) were evaluated by Kaplan-Meier methods. Overall response rate (ORR) was also analyzed, with quality of life and biomarker analyses planned. RIGHT Choice is registered at ClinicalTrials.gov (NCT03839823). Results: A total of 222 pts (112 RIB + ET; 110 CT) were enrolled from Feb 2019 to Nov 2021. Pts with symptomatic visceral metastases (n=150; 67.6%), rapid disease progression (n=41; 18.5%), and markedly symptomatic non-visceral metastases (n=31; 14.0%) were included. Overall, 116 pts (52.3%) had visceral crisis based on guideline definitions. A majority of pts (n=190; 85.6%) had tumors that were ≥50% ER+. At data cutoff (Apr 12, 2022), median follow-up was 24.1 mo; 45.5% and 23.6% of pts remained on treatment in the RIB + ET arm and combination CT arm, respectively. The primary endpoint was met, with a statistically significant PFS benefit of ≈1 year for RIB + ET vs combination CT (mPFS, 24.0 vs 12.3 mo; hazard ratio, 0.54; 95% CI, 0.36-0.79; P=.0007). OS data were immature at data cutoff. The mTTF was ≈10 mo longer for RIB + ET vs CT (18.6 vs 8.5 mo; hazard ratio, 0.45; 95% CI, 0.32-0.63). The ORR was similar for RIB + ET vs CT (65.2% vs 60.0%). No new safety signals were observed in pts on RIB. Lower rates of treatment-related serious adverse events (AEs; 1.8% vs 8.0%) and lower rates of discontinuation due to treatment-related AEs (7.1% vs 23.0%) were seen with RIB + ET vs CT, respectively. AEs observed with combination CT were consistent with the published data. Conclusions: This analysis demonstrated a statistically significant and clinically meaningful PFS benefit with RIB + ET over combination CT in the first-line pre/perimenopausal pt population with aggressive HR+/HER2− ABC disease. This is the first study comparing a CDK4/6i + ET vs combination CT and demonstrating the superiority of RIB + ET in aggressive HR+/HER2− ABC. This evidence supports RIB+ ET use as a preferred option for this pt population. Citation Format: Yen-Shen Lu, Eznal Izwadi Bin Mohd Mahidin, Hamdy Azim, Yeşim ERALP, Yoon-Sim Yap, Seock-Ah Im, Julie Rihani, James Bowles, Teresa Delgar Alfaro, Jiwen Wu, Melissa Gao, Khemaies Slimane, Nagi El Saghir. Primary results from the randomized Phase II RIGHT Choice trial of premenopausal patients with aggressive HR+/HER2− advanced breast cancer treated with ribociclib + endocrine therapy vs physician’s choice combination chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS1-10.

Abstract PD17-08: Pooled gene expression analysis and association with treatment response in patients with HR+/HER2− advanced breast cancer in the MONALEESA-2, -3, and -7 trials

Abstract Background: The Phase III MONALEESA (ML)-2, -3, and -7 trials showed significant improvement in progression-free survival (PFS) and overall survival (OS) with ribociclib (RIB) + endocrine therapy (ET) over placebo (PBO) + ET in patients (pts) with HR+/HER2− advanced breast cancer (ABC); improvement in OS with cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) has been observed in some, but not all clinical trials. Gene expression analyses for each separate ML study were reported previously. Given the differences in CDK4 vs CDK6 inhibition between RIB and other CDK4/6i, we evaluated the association between cell cycle (CC)–related genes and outcomes based on pooled analysis of gene expression using tumor samples from the ML-2, -3, and -7 trials. Methods: Gene expression data were generated from pre-treatment archival tumor samples (primary, 73%; metastatic, 27%) with a customized NanoString nCounter panel (781 genes) including genes involved in CC, other signaling pathways, and breast cancer biology. Samples were pooled from 1139 pre- and postmenopausal pts with HR+/HER2− ABC across the 3 ML studies, which included pts on first- and second-line therapy. Data were categorized into training (80%) and test (20%) datasets. The training dataset was used to analyze each gene (modeled continuously) individually for an association with PFS, and genes with a gene × treatment (tx) interaction P value <.10 were evaluated in the test dataset. Genes or gene signatures were classified by tertiles based on expression level (low/medium/high). For each tertile, median (m) PFS was calculated by the Kaplan-Meier method, and hazard ratios (HRs) of tx benefit (RIB vs PBO) were estimated. A Cox proportional hazards model adjusting for clinical covariates was used. A machine learning approach (elastic net survival model with stability selection), which used available gene expression data and select clinical factors and their interactions with tx arms, was applied to predict PFS. Results: This report focused on CC-related genes and signatures. Gene expression levels of CDKN2B and the expression ratio of CCND1/CDKN2A showed a predictive relationship with benefit from RIB in both training and test sets (Table). PFS benefit with RIB was consistent regardless of the CDK4/CDK6 expression ratio or level of expression of CCNE1, CDK2, RB1, combined CC-related genes, E2F gene signatures, RB gene signature, combined DNA-replication genes, or combined proliferation-related genes. A machine learning approach identified a clinico-genomic signature that was prognostic for PFS benefit with RIB. Selected variables included gene expression levels of FXBO5, PGR, RBBP8, and STC2 and several clinical features (tx arm, de novo disease, prior ET, and visceral disease). Pts with a low signature score had a longer mPFS vs pts with a high signature score, in the RIB (HR, 0.37; 95% CI, 0.22-0.62) and PBO (HR, 0.30; 95% CI, 0.15-0.59) arms. Conclusion: In the largest pooled analysis of the association of gene expression profile data with CDK4/6i tx response in pts with HR+/HER2− ABC, the PFS benefit with RIB + ET over ET alone was consistent irrespective of expression levels of most CC genes. Variation in magnitude of RIB benefit was observed, depending on CDKN2B expression levels, CCND1/CDKN2A expression ratio, and machine learning–derived signature scores. The clinico-genomic CDK4/6i signature requires validation in additional datasets. Table 1: Progression-Free Survival by Gene Expression Subgroup Citation Format: Aditya Bardia, Faye Su, Nadia Solovieff, Fabrice Andre, Carlos Arteaga, Patrick Neven, Yoon-Sim Yap, Yen-Shen Lu, Stephen K. Chia, Dennis Slamon, Seock-Ah Im, Arunava Chakravartty, Agnes Lteif, Tetiana Taran, Debu Tripathy. Pooled gene expression analysis and association with treatment response in patients with HR+/HER2− advanced breast cancer in the MONALEESA-2, -3, and -7 trials [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD17-08.