Outcomes for patients with hormone receptor-positive HER2-negative (HR+ HER2-) advanced breast cancer (ABC) have improved considerably in recent years and CDK4/6 inhibitors are the preferred first-line therapy for most patients. Newer therapeutic classes include PI3K/AKT inhibitors, oral selective estrogen receptor degraders, proteolysis-targeting chimeras, PARP inhibitors, and antibody-drug conjugates. The development and regulatory approval of these new therapies to treat HR+ HER2- breast cancer raises the question of how to use and sequence this fast-growing armamentarium to maximize benefit for individual patients. Disease progression and resistance mechanisms emerging on treatment (therapeutic pressure) add further complexity by inducing molecular alterations; thus, a clear understanding of the mechanisms behind resistance to both endocrine and CDK4/6 inhibitor therapies and their implications for subsequent treatment is critical. In principle, the most effective and tolerable drugs should be used first with the goals of delaying chemotherapy and offering patients the best quality and duration of life. This review aims to explain the evolving treatment landscape for HR+ HER2- ABC and provides the scientific background for developing future treatment algorithms driven by preclinical and clinical results.

Forest plot for the GEICAM_CIBOMA translational study cohort primary endpoint of recurrence-free survival (RFS) on the capecitabine arm versus observation arm for basal-like/non-basal categories variables

Multivariate Cox regression analysis of overall survival (OS) for basal-like/non-basal categories variables in the GEICAM_CIBOMA translational study cohort

PURPOSE:In a prespecified GEICAM_CIBOMA trial (NCT00130533) correlative analysis, PAM50 non-basal-like breast cancer (non-BLBC) status distinguished patients with triple-negative breast cancer (TNBC) who are most likely to benefit from adjuvant capecitabine. The standardized forkhead box C1 (FOXC1) IHC test has demonstrated strong reliability in classifying the BLBC subtype throughout TNBC cohorts. This translational analysis aimed to evaluate the prognostic/predictive significance of BLBC classification by FOXC1 IHC in the phase III GEICAM_CIBOMA clinical trial. EXPERIMENTAL DESIGN:Tumor tissues from patients with TNBC randomized to standard (neo)adjuvant chemotherapy followed by capecitabine versus observation were analyzed using the standardized FOXC1 IHC test to assess its BLBC/non-BLBC TNBC subtyping capacity as a distant relapse-free survival clinical outcome predictor of capecitabine benefit (exploratory endpoints: disease-free survival, overall survival, and recurrence-free survival). RESULTS:A total of 705 (80.5%) patients from the GEICAM_CIBOMA trial were evaluable for FOXC1 expression analysis, with balanced distribution between the trial's treatments. FOXC1 proportion/intensity (VFOXC1) score-based subtyping demonstrated a strong association [AUC = 0.87; 95% confidence interval (CI), 0.84-0.91] and agreement (κ index = 0.43; P < 0.0001) with PAM50 molecular subtyping. VFOXC1 non-BLBC TNBC subtype was a significant independent predictor of clinical benefit with capecitabine for distant relapse-free survival (HR, 0.44; 95% CI, 0.25-0.76; P = 0.003). This predictive effect of VFOXC1 non-BLBC on capecitabine efficacy was further confirmed at disease-free survival (HR, 0.47; 95% CI, 0.28-0.78; P = 0.003), overall survival (HR, 0.48; 95% CI, 0.24-0.96; P = 0.038), and recurrence-free survival (HR, 0.39; 95% CI, 0.22-0.72; P = 0.002). CONCLUSIONS:This ambispective GEICAM_CIBOMA translational analysis validated FOXC1-based basal-like/non-basal-like subtyping as a pragmatic alternative to PAM50 subtyping and independently predicted the benefit of adding capecitabine to standard (neo)adjuvant chemotherapy in TNBC.

1098 Background: New therapies are urgently needed for aTNBC. The PI3K/AKT/mTOR pathway and its link to chemoresistance warrant further investigation in pre-treated TNBC patients. The pan-AKT inhibitor IPA, alone or combined, has shown promise for treating advanced solid tumors. This study assessed the toxicity and efficacy of IPA with non-taxane CT in aTNBC pts. Methods: PATHFINDER (NCT04464174) is a multicenter, open-label, non-comparative, phase IIa trial with a safety run-in phase. Taxane-pretreated aTNBC pts with 1-2 prior CT lines for advanced disease and ECOG 0-1 were eligible. Based on prior treatment and available slots, pts received 21-day cycles of IPA (oral, 400 mg/d for 14 d) either with capecitabine (CA) (oral, 2 g/m2/d for 14 d) (arm A); eribulin (E) (IV, 1.23 mg/m2 on d1 and d8) (arm B); or carboplatin plus gemcitabine (CG) (IV, AUC 5 on d1 and 1000 mg/m2 on d1 and d8, respectively) (arm C) until disease progression (PD) or unacceptable toxicity. Initially, the safety run-in phase included 3 pts/arm to determine phase IIa doses based on the toxicity observed after 2 cycles. The primary endpoint was incidence of adverse events (AEs) as per NCI-CTCAE v.5.0. Key secondary endpoints included progression-free survival (PFS), overall survival (OS), and objective response rate (ORR). Analysis was exploratory with no hypothesis testing. Results: From September 2020 to October 2022, 54 pts were assigned to arms A (n = 22), B (n = 25), and C (n = 7). In arm C, 4 additional pts received a lower dose level of IPA (300 mg/d) in the safety run-in phase. Based on the toxicity profile, this arm did not proceed with the expansion phase. At data cutoff (10th November 2023), median follow-up was 13.8 (2.4-35.5, arm A) and 11.2 (0.2-36.9, arm B) months (mo). All pts discontinued treatment, mainly because of PD (74.1%). Discontinuations due to AEs were 4.5% and 4% in arms A and B, respectively. Incidence of treatment-related (1) any grade (G) TEAEs was 81.8% and 88% and (2) SAEs was 4.5% and 20% for arms A and B, respectively. G≥3 TEAEs occurring in ≥10% of pts are shown (Table). No treatment-related deaths were reported. Median PFS was 2.7 (95%CI, 1.5-4.1) and 3.8 (95%CI, 1.5-9.6) mo; median OS was 15.5 (95%CI, 11.8-19.2) and 11.5 (95%CI, 8.8-25.1) mo; and ORR was 9.1% and 36% for arms A and B, respectively. Conclusions: Combining IPA with CA and E presented an acceptable safety profile. However, adding IPA to CG was not tolerable. E + IPA showed promising efficacy regardless of PI3K/AKT status that merits further evaluation. Clinical trial information: NCT04464174 . [Table: see text]

Metastatic triple-negative breast cancer has a poor prognosis and poses significant therapeutic challenges. Until recently, limited therapeutic options have been available for patients with advanced disease after failure of first-line chemotherapy. The aim of this review is to assess the current evidence supporting second-line treatment options in patients with metastatic triple-negative breast cancer. Evidence was reviewed from controlled clinical trials in which eribulin, vinorelbine, capecitabine, gemcitabine, gemcitabine plus carboplatin, fam-trastuzumab-deruxtecan, sacituzumab govitecan, olaparib, and talazoparib were used in the second-line treatment for metastatic breast cancer, either as study drugs or as comparators. The benefit of treatment was evaluated using the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale. Based on the evidence review, sacituzumab govitecan was identified as the preferred second-line treatment option for patients with metastatic triple-negative breast cancer, supported by clinical evidence and consensus across international clinical guidelines. Olaparib and talazoparib are of use in patients with human epidermal growth factor receptor 2-negative metastatic breast cancer and germline BRCA1/2 mutations. Exploratory data for fam-trastuzumab-deruxtecan suggest a survival benefit in human epidermal growth factor receptor 2-low, hormone-receptor-negative patients, but further solid evidence is required. Other chemotherapies with lower European Society for Medical Oncology-Magnitude of Clinical Benefit Scale scores may continue to be useful in highly selected patients.

Survival analyses showing the secondary endpoint of disease-free survival (DFS) for patients randomly assigned to capecitabine or observation in the GEICAM_CIBOMA translational study cohort

Background: In MONARCH 2, the addition of abemaciclib to fulvestrant significantly fi cantly improved both progression-free survival (PFS) and overall survival (OS) in patients with hormone receptor-positive (HR+), + ), human epidermal growth factor receptor 2-negative (HER2-)- ) advanced breast cancer (ABC) with disease progression on prior endocrine therapy. In MONARCH 3, the addition of abemaciclib to a nonsteroidal aromatase inhibitor (NSAI) as initial therapy for HR+, + , HER2-- ABC significantly fi cantly improved PFS. Here, we present the prespecified fi ed fi nal OS results for MONARCH 3. Patients and methods: MONARCH 3 is a randomized, double-blind, phase III study of abemaciclib plus NSAI (anastrozole or letrozole) versus placebo plus NSAI in postmenopausal women with HR+, + , HER2-- ABC without prior systemic therapy in the advanced setting. The primary objective was investigator-assessed PFS; OS was a gated secondary endpoint, and chemotherapy-free survival was an exploratory endpoint. Results: A total of 493 women were randomized 2 : 1 to receive abemaciclib plus NSAI (n = 328) or placebo plus NSAI (n = 165). After a median follow-up of 8.1 years, there were 198 OS events (60.4%) in the abemaciclib arm and 116 (70.3%) in the placebo arm (hazard ratio, 0.804; 95% confidence fi dence interval 0.637-1.015; P = 0.0664, non-significant). fi cant). Median OS was 66.8 versus 53.7 months for abemaciclib versus placebo. In the subgroup with visceral disease, there were 113 OS events (65.3%) in the abemaciclib arm and 65 (72.2%) in the placebo arm (hazard ratio, 0.758; 95% confidence fi dence interval 0.558-1.030; P = 0.0757, non-significant). fi cant). Median OS was 63.7 months versus 48.8 months for abemaciclib versus placebo. The previously demonstrated PFS benefit fi t was sustained, and chemotherapy-free survival numerically improved with the addition of abemaciclib. No new safety signals were observed. Conclusions: Abemaciclib combined with an NSAI resulted in clinically meaningful improvement in median OS (intent- to-treat population: 13.1 months; subgroup with visceral disease: 14.9 months) in patients with HR+ + HER2-- ABC; however, statistical significance fi cance was not reached.

516 Background: In a prespecified correlative analysis of the GEICAM/2003-11_CIBOMA/2004-01 phase III clinical trial (CIBOMA trial), PAM50 non-basal status identified triple-negative breast cancer (TNBC) patients (pts) most likely to benefit from adjuvant capecitabine (cap). FOXC1 cell plasticity/metastasis transcriptional driver assessment by standardized Veresca FOXC1 Immunohistochemistry (IHC) BC test (Veresca) has shown rigorous capacity to identify basal-like breast cancer (BLBC) subtype throughout TNBC cohorts. We sought to explore the concordance of BLBC identification by FOXC1 with PAM50 molecular subtyping and its prognostic/predictive value in the CIBOMA trial (NCT00130533). Methods: We analyzed FOXC1 expression (Veresca, Onconostic Technologies) and the Ki-67 Antigen MIB-1 (Dako) by IHC on tumors from 705 TNBC pts randomized to maintenance with cap (357, 51%) vs observation (obs) (348, 49%) after standard (neo)adjuvant chemotherapy (CT). Veresca score (VFOXC1) was defined as % of tumor cells with positive nuclear staining (Proportion Score 0-5) plus staining intensity (Intensity Score 0-3). BLBC subtyping by Veresca (cutoff ≥4) and PAM50 signature (Nanostring) were compared using ROC analysis and Kappa index (KI). Ki67 ≥20% cutoff was applied. Cox regression models were assessed to predict DRFS (primary endpoint), DFS and OS (secondary endpoints). Results: VFOXC1≥4 identified 460 (65%) BLBC pts in this CIBOMA trial cohort (229 (49.8%) treated with cap, and 231 (50.2%) in obs). VFOXC1 detection was not associated with any clinicopathological characteristic. VFOXC1 expression significantly correlated with PAM50 BLBC subtyping (ROC analysis AUC 0.874, KI 0.43) but moderately with IHC subtyping (AUC 0.548). VFOXC1 BLBC subtype was not associated with DRFS (HR=0.94; 95%CI 0.68-1.30; p=0.713) in the entire cohort. However, VFOXC1 non-BLBC subtype was a strong independent predictor of cap benefit for DRFS (univariate analysis, interaction p-value p=0.117; HR=0.53; 95%CI 0.31-0.90; p=0.019; multivariate analysis, HR=0.44; 95%CI 0.25–0.76; p=0.003). This predictive effect of VFOXC1 non-BLBC on cap benefit was also confirmed at DFS (HR=0.47; 95%CI 0.28–0.78; p=0.003) and OS (HR=0.48; 95%CI 0.24–0.96; p=0.038), and was independent of Ki67 proliferation status (multivariate DRFS; Ki67<20%, HR=0.41; 95%CI 0.20-0.82; p=0.012; Ki67≥20%, HR=0.31; 95%CI 0.10-0.97; p=0.045). VFOXC1 non-BLBC subtype had no association with clinical outcome in obs arm. Conclusions: In the CIBOMA TNBC trial, the non-BLBC definition by a single biomarker (FOXC1 Veresca) provided prognostic and predictive value of cap benefit after (neo)adjuvant CT, corroborating our previous findings by PAM50 and IHC non-BLBC subtyping. This is a pragmatic option to effectively apply findings from this trial in the real-world setting. Clinical trial information: NCT00130533 .

516 Background: In a prespecified correlative analysis of the GEICAM/2003-11_CIBOMA/2004-01 phase III clinical trial (CIBOMA trial), PAM50 non-basal status identified triple-negative breast cancer (TNBC) patients (pts) most likely to benefit from adjuvant capecitabine (cap). FOXC1 cell plasticity/metastasis transcriptional driver assessment by standardized Veresca FOXC1 Immunohistochemistry (IHC) BC test (Veresca) has shown rigorous capacity to identify basal-like breast cancer (BLBC) subtype throughout TNBC cohorts. We sought to explore the concordance of BLBC identification by FOXC1 with PAM50 molecular subtyping and its prognostic/predictive value in the CIBOMA trial (NCT00130533). Methods: We analyzed FOXC1 expression (Veresca, Onconostic Technologies) and the Ki-67 Antigen MIB-1 (Dako) by IHC on tumors from 705 TNBC pts randomized to maintenance with cap (357, 51%) vs observation (obs) (348, 49%) after standard (neo)adjuvant chemotherapy (CT). Veresca score (VFOXC1) was defined as % of tumor cells with positive nuclear staining (Proportion Score 0-5) plus staining intensity (Intensity Score 0-3). BLBC subtyping by Veresca (cutoff ≥4) and PAM50 signature (Nanostring) were compared using ROC analysis and Kappa index (KI). Ki67 ≥20% cutoff was applied. Cox regression models were assessed to predict DRFS (primary endpoint), DFS and OS (secondary endpoints). Results: VFOXC1≥4 identified 460 (65%) BLBC pts in this CIBOMA trial cohort (229 (49.8%) treated with cap, and 231 (50.2%) in obs). VFOXC1 detection was not associated with any clinicopathological characteristic. VFOXC1 expression significantly correlated with PAM50 BLBC subtyping (ROC analysis AUC 0.874, KI 0.43) but moderately with IHC subtyping (AUC 0.548). VFOXC1 BLBC subtype was not associated with DRFS (HR=0.94; 95%CI 0.68-1.30; p=0.713) in the entire cohort. However, VFOXC1 non-BLBC subtype was a strong independent predictor of cap benefit for DRFS (univariate analysis, interaction p-value p=0.117; HR=0.53; 95%CI 0.31-0.90; p=0.019; multivariate analysis, HR=0.44; 95%CI 0.25–0.76; p=0.003). This predictive effect of VFOXC1 non-BLBC on cap benefit was also confirmed at DFS (HR=0.47; 95%CI 0.28–0.78; p=0.003) and OS (HR=0.48; 95%CI 0.24–0.96; p=0.038), and was independent of Ki67 proliferation status (multivariate DRFS; Ki67<20%, HR=0.41; 95%CI 0.20-0.82; p=0.012; Ki67≥20%, HR=0.31; 95%CI 0.10-0.97; p=0.045). VFOXC1 non-BLBC subtype had no association with clinical outcome in obs arm. Conclusions: In the CIBOMA TNBC trial, the non-BLBC definition by a single biomarker (FOXC1 Veresca) provided prognostic and predictive value of cap benefit after (neo)adjuvant CT, corroborating our previous findings by PAM50 and IHC non-BLBC subtyping. This is a pragmatic option to effectively apply findings from this trial in the real-world setting. Clinical trial information: NCT00130533 .

TPS2091 Background: Brain metastases (BM) are a common and severe complication of cancer, resulting in increased morbidity and mortality. Highest incidence of BM is observed in advanced non–small cell lung cancer (aNSCLC) and metastatic breast cancer (mBC). Metastatic solid tumors with leptomeningeal disease (LMD) have a dismal outcome. Patients (pts) with BM and/or LMD have very limited treatment options. Antibody drug conjugates have shown high intracranial response rates and HER3 is highly expressed in CNS metastases of aNSCLC and mBC. Patritumab deruxtecan (HER3-DXd), an antibody drug conjugate combining an anti-HER3 antibody with a topoisomerase I inhibitor. It has demonstrated promising results in mBC and EGFR-mutated NSCLC, as shown in the HERTHENA-Lung 01 study, in which a CNS objective response rate (ORR) of 33.3% was achieved. We hypothesized that HER3-DXd may have clinical activity in active BM from mBC and aNSCLC, and in LMD from metastatic solid tumors. This study aims to evaluate the efficacy and safety of HER3-DXd in these pts. Methods: This is an international, multicenter, single-arm, three-cohort, phase II trial (NCT05865990). A total of 60 evaluable pts (20 per cohort) will be recruited from Austrian and Spanish hospitals and assigned to one of the following cohorts: (1) HER2+, HER2- and triple negative mBC with BM, (2) aNSCLC with BM, and (3) metastatic solid tumors with LMD. Key inclusion criteria are: age ≥18 years, ≥1 line of prior systemic treatment, histologically documented disease, ECOG 0-2, and left ventricular ejection fraction ≥50% (for all cohorts); newly diagnosed/progressing BM with ≥1 measurable brain lesion (≥10mm) by MRI (for cohorts 1 and 2); and LMD with CSF positive cytology and/or MRI (for cohort 3). Pts will receive 5.6 mg/kg of intravenous HER3-DXd on day 1 of every 21-day cycle until disease progression or unacceptable toxicity. Primary endpoints are intracranial ORR (IC-ORR) per local investigator in cohorts 1 and 2 according to RANO-BM, and 3-month OS in cohort 3. Secondary endpoints are OS, ORR, progression-free survival, time to response and duration, clinical benefit rate, safety, tolerability, quality of life evaluation and neurocognitive function evaluation by NANO scale in all cohorts. The sample size was based on Simon’s two-stage design. One-sided alternative hypotheses are IC-ORR ≥25% in cohorts 1 and 2, and 3-month OS ≥25% in cohort 3. Null hypotheses are IC-ORR and 3-month OS ≤5%. Type I error is 10% and power 88%. This is the first prospective clinical trial to evaluate the intra-/extracranial efficacy and safety of HER-DXd in pretreated mBC and aNSCLC with BM, and metastatic solid tumors with LMD. If positive, TUXEDO-3 could streamline the introduction of HER3-DXd as a new treatment paradigm for these pts, who currently have very limited therapeutic options. Clinical trial information: NCT05865990 .

IntroductionAdvancements in monoclonal antibodies, tyrosine kinase inhibitors, and antibody drug conjugates (ADCs) have notably enhanced outcomes for metastatic HER2-positive breast cancer patients. Despite the expanding treatment options and clinical complexities, determining the optimal sequence of HER2-targeted therapies remains partly uncertain, influenced by various factors.MethodsTo refine HER2-positive metastatic breast cancer management, particularly regarding tucatinib's position, a Steering Committee of leading oncologists in breast cancer care devised a panel of statements via a Delphi approach, focusing on five key topics: general clinical management, therapeutic approaches for patients with HER2-positive breast cancer and brain metastases, treatment sequence, and tucatinib's safety and efficacy.ResultsA total of 29 statements were deliberated, with strong consensus achieved for most. However, no consensus emerged regarding the management of brain progression alongside stable extracranial disease: 48% advocated for switching to tucatinib, while 53% favored a stereotactic brain radiotherapy (SBRT) approach if feasible.ConclusionThe unanimous consensus attained in this Delphi panel, particularly regarding tucatinib's efficacy and safety, underscores oncologists' recognition of its clinical significance based on existing trial data. These findings align closely with current literature, shedding light on areas necessitating further investigation, not thoroughly explored in prior studies. Moreover, the results underscore the scarcity of data on managing brain progression alongside stable extracranial disease, emphasizing the imperative for dedicated research to address these gaps and yield definitive insights.

Abstract Background: Abemaciclib is approved both for high-risk early breast cancer as well as advanced breast cancer (ABC) in the first- and second-line setting. In MONARCH 2, the addition of abemaciclib to fulvestrant significantly improved both progression-free survival (PFS) and overall survival (OS) in patients with HR+, HER2- ABC with disease progression on prior endocrine therapy (ET). In MONARCH 3, the addition of abemaciclib to a nonsteroidal aromatase inhibitor (NSAI) significantly improved PFS (HR, 0.540; 95% CI, 0.418-0.698; p=0.000002) as initial therapy in HR+, HER2- ABC. At the last interim OS analysis (~252 events, at 5.8 years follow-up [FU]), a numerically favorable median OS difference (12.6 months) was observed (HR, 0.754; 95% CI, 0.584-0.974; p=0.0301, non-significant [NS]). Here, we present the final OS analysis of MONARCH 3 (NCT02246621). Methods: MONARCH 3 is a randomized, double-blind, Phase 3 study of abemaciclib + NSAI (anastrozole or letrozole) vs placebo + NSAI in postmenopausal women with HR+, HER2- ABC without prior systemic therapy in the advanced setting. OS was a gated secondary endpoint and chemotherapy-free survival (CFS) an exploratory endpoint. Final OS analysis was planned after approximately 315 OS events had occurred in the intent-to-treat (ITT) population with a split alpha between the ITT population and the subgroup with visceral disease (sVD) according to a prespecified graphical testing scheme. Kaplan-Meier method and stratified Cox proportional hazards models were used for time-to-event analyses. All reported p-values are two-sided. Results A total of 493 women were randomized 2:1 to receive abemaciclib + NSAI (n=328) or placebo + NSAI (n=165). After a median FU of 8.1 years, 7% of patients were still receiving treatment in the abemaciclib arm vs 3% in the placebo arm. In the ITT population, 314 OS events were observed (198 deaths among 328 patients [60%] in the abemaciclib arm and 116 among 165 [70%] in the placebo arm; HR, 0.804; 95% CI, 0.637-1.015; p=0.0664, NS). Median OS was 66.8 months in the abemaciclib arm and 53.7 months in the placebo arm, a numerical difference of 13.1 months in the ITT population. In the sVD, 178 events were observed (113 deaths among 173 patients [65%] in the abemaciclib arm and 65 among 90 [72%] in the placebo arm; HR, 0.758; 95% CI, 0.558-1.030; p=0.0757, NS). Median OS was 63.7 months in the abemaciclib arm and 48.8 months in the placebo arm, a numerical difference of 14.9 months in the sVD. Consistent OS differences were observed across prespecified subgroups. PFS benefit was sustained (median 29.0 vs 14.8 months; HR, 0.535; 95% CI, 0.429-0.668; nominal p<0.0001) with substantial difference in 6-year PFS rates (23.3% vs 4.3% for abemaciclib vs placebo). CFS was also improved with abemaciclib vs placebo (median 46.7 vs 30.6 months; HR, 0.693; 95% CI, 0.557-0.863; nominal p=0.0010). No new safety signals were observed with longer term use. Conclusion In patients with HR+, HER2- ABC, abemaciclib in combination with a NSAI resulted in numerically longer OS compared to NSAI alone; however, statistical significance was not reached after a median FU of 8.1 years. The clinically meaningful improvement in median OS (>13 months) combined with the sustained significant improvement in median PFS (>14 months) and substantial extension in median CFS (>16 months) continue to support the use of abemaciclib in combination with NSAI as first-line therapy in ABC. Citation Format: Matthew Goetz, Masakazu Toi, Jens Huober, Joo Hyuk Sohn, Olivier Trédan, Inhae Park, Mario Campone, Shin-Cheh Chen, Luis Manual Manso, Shani Paluch-Shimon, Orit C. Freedman, Valerie Andre, Abhijoy Saha, Gertjan van Hal, Ashwin Shahir, Hiroji Iwata, Stephen RD Johnston, Joyce O'Shaughnessy, Xavier Pivot, Sara Tolaney, Sara Hurvitz, Antonio Llombart. MONARCH 3: Final overall survival results of abemaciclib plus a nonsteroidal aromatase inhibitor as first-line therapy for HR+, HER2- advanced breast cancer [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 GS01-12.

The better survival of Human Epidermal growth factor receptor-type 2 positive (HER2+) breast cancer (BC) patients unmasked the biological predilection of this BC subtype for development of brain metastasis (BM). Indeed, central nervous system (CNS) is a frequent metastatic site for HER2+ advanced BC patients. Over the last years, new therapeutic strategies targeting the HER2 protein have been introduced for systemic treatment of HER2+ BC - either tyrosine kinase inhibitors, monoclonal antibodies, or antibody-drug conjugates. Patients with BMs have a poorer outcome, compared with patients without BMs, but their prognosis is also improving with the introduction of new anti HER2+ - targeted therapies. The

The Epi-GEICAM study comprises 1017 invasive BC cases matched with controls of similar age (49 ± 9 years) and residence. Diet and OO consumption were collected through a validated food frequency questionnaire. 75% of women referred OO, common (refined) or virgin, as the main fat source. Using conditional logistic regression models, we compared different scenarios of type and frequency of OO consumption, using as reference those women not always using OO for the three culinary practices (seasoning, cooking, and frying) and adding <2 tablespoons (tbsps.) per day during the meal to bread, salad, or dishes. A substantial inverse association was observed in those women always using VOO for the three culinary practices and consuming ≥2 tbsps. of OO per day during meals (adjusted OR, 0.72; 95% CI: 0.51, 1.03; P = 0.07). Potential benefits from OO consumption, at least as regards the protection provided for BC, could be mostly conferred with VOO, and when its consumption is high.

Abstract Purpose: We do not yet have validated biomarkers to predict response and outcome within hormone receptor–positive/HER2-positive (HR+/HER2+) breast cancer. The PAM50-based chemo-endocrine score (CES) predicts chemo-endocrine sensitivity in hormone receptor–positive/HER2-negative (HR+/HER2−) breast cancer. Here, we evaluate the relationship of CES with response and survival in HR+/HER2+ breast cancer. Experimental Design: Intrinsic subtype and clinicopathologic data were obtained from seven studies in which patients were treated with HER2-targeted therapy either with endocrine therapy (ET) or with chemotherapy (CTX). CES was evaluated as a continuous variable and categorically from low to high scores [CES-C (chemo-sensitive), CES-U (uncertain), and CES-E (endocrine-sensitive)]. We first analyzed each dataset individually, and then all combined. Multivariable analyses were used to test CES association with pathologic complete response (pCR) and disease-free survival (DFS). Results: A total of 457 patients were included (112 with ET and 345 with CTX). In the combined cohort, CES-C, CES-U, and CES-E were identified in 60%, 23%, and 17% of the patients, respectively. High CES (i.e., CES-E) was associated with a lower probability of achieving pCR independently of clinical characteristics, therapy, intrinsic subtype, and study (adjusted OR = 0.42; P = 0.016). A total of 295 patients were analyzed for DFS with a median follow-up of 66 months. High CES was also associated with better DFS (adjusted HR, 0.174; P = 0.003) independently of pCR, clinical characteristics and intrinsic subtype. In patients with residual disease, the adjusted DFS HR of CES was 0.160 (P = 0.012). Conclusions: In HER2+/HR+ breast cancer, CES is useful for predicting chemo-endocrine sensitivity and provides additional prognostication beyond intrinsic subtype and clinicopathologic characteristics.

This prospective, phase II study evaluated novel biomarkers as predictors of response to bevacizumab in patients with breast cancer (BC), using serial imaging methods and gene expression analysis. Patients with primary stage II/III BC received bevacizumab 15 mg/kg (cycle 1; C1), then four cycles of neoadjuvant docetaxel doxorubicin, and bevacizumab every 3 weeks (C2–C5). Tumour proliferation and hypoxic status were evaluated using 18F-fluoro-3′-deoxy-3′-L-fluorothymidine (FLT)- and 18F-fluoromisonidazole (FMISO)-positron emission tomography (PET) at baseline, and during C1 and C5. Pre- and post-bevacizumab vascular changes were evaluated using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Molecular biomarkers were assessed using microarray analysis. A total of 70 patients were assessed for treatment efficacy. Significant decreases from baseline in tumour proliferation (FLT-PET), vascularity, and perfusion (DCE-MRI) were observed during C1 (p ≤ 0.001), independent of tumour subtype. Bevacizumab treatment did not affect hypoxic tumour status (FMISO-PET). Significant changes in the expression of 28 genes were observed after C1. Changes in vascular endothelial growth factor receptor (VEGFR)-2p levels were observed in 65 patients, with a > 20% decrease in VEGFR-2p observed in 13/65. Serial imaging techniques and molecular gene profiling identified several potentially predictive biomarkers that may predict response to neoadjuvant bevacizumab therapy in BC patients.

The addition of CDK4 and 6 inhibitors (abemaciclib, palbociclib or ribociclib) to endocrine therapy, as first-line treatment or following progression after initial endocrine therapy, significantly increased progression-free survival, objective response rates and in some trials overall survival, compared with endocrine therapy alone in HR+ and HER2- breast metastatic breast cancer. These CDK4 and 6 inhibitors are now approved in this context and have become a new standard of care. A hypothesis-generating exploratory analysis suggested that the addition of abemaciclib to endocrine therapy showed the largest effects in subgroups of women with indicators of poor prognosis, although these data require confirmation. This review provides updated clinical trial data for all three drugs in metastatic breast cancer, focusing on abemaciclib, the most recently approved agent.