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Background: The aim of this study was to investigate whether the PAM-50-based 46-gene assay carries prognostic value for risk of local recurrence of breast cancer. Methods: The Austrian Breast and Colorectal Cancer Study Group (ABCSG) 8 RCT compared 5 years of tamoxifen with tamoxifen for 2 years followed by anastrozole for 3 years in postmenopausal women with endocrine receptor-positive breast cancer. This study included patients from the trial who had breast-conserving surgery for whom tumour blocks were available for PAM-50 analysis. Results: Tumour blocks from 1204 patients who had breast-conserving surgery were available for the PAM-50 analysis, and 1034 of these received radiotherapy. After a median follow-up of 10.8 years, 23 local events had been observed, corresponding to an overall local recurrence risk of 2.2 per cent. Univariable competing-risk analysis demonstrated that patients at low risk according to PAM-50 analysis (risk-of-recurrence (ROR) score less than 57) had a significantly lower incidence of local recurrence than those in the highrisk group at 5 years (0.1 (95 per cent c.i. 0 to 0.7) versus 2.2 (0.9 to 4.6) per cent respectively; subhazard ratio (SHR) 17.18, 95 per cent c.i. 2.06 to 142.88; P=0.009) and 10 years (0.9 (0.4 to 2.0) versus 3.8 (1.9 to 6.6) per cent; SHR 4.76, 1.72 to 13.17; P=0.003). Multivariable analyses that included ROR score, age, tumour size, nodal status, type of surgery, tumor grade, and trial-specific endocrine therapy confirmed that ROR score was an independent prognostic factor for risk of local recurrence. Analysis of the women randomized to radiotherapy or control after breast conservation showed that PAM-50 was not predictive of radiotherapy effect. Conclusion: PAM-50 can be used as a prognostic tool for local recurrence risk in postmenopausal women with hormone receptorpositive breast cancer treated with endocrine therapy. The test was not predictive for the benefit of radiotherapy. [ABSTRACT FROM AUTHOR]

Background:We investigated whether body mass index (BMI) can be used as a predictive parameter indicating patients who benefit from extended aromatase inhibitor (AI) treatment.Methods:The ABCSG-6a trial re-randomised event-free postmenopausal hormone receptor-positive patients from the ABCSG-6 trial to receive either 3 additional years of endocrine therapy using anastrozole vs nil. In this retrospective analysis, we investigated the prognostic and predictive impact of BMI on disease outcome and safety.Results:In all, 634 patients (177 normal weight, 307 overweight, and 150 obese) patients were included in this analysis. Normal weight patients with additional 3 years of anastrozole halved their risk of disease recurrence (disease-free survival (DFS) HR 0.48; P=0.02) and death (HR 0.45; P=0.06) and had only a fifth of the risk of distant metastases (HR 0.22; P=0.05) compared with normal weight patients without any further treatment. In contrast, overweight+obese patients derived no benefit from additional 3 years of anastrozole (DFS HR 0.93; P=0.68; distant recurrence-free survival HR 0.91; P=0.78; and OS HR 0.9; P=0.68). The possible predictive impact of BMI on extended endocrine treatment could be strengthened by a Cox regression interaction model between BMI and treatment (P=0.07).Conclusion:Body mass index may be used to predict outcome benefit of extended AI treatment in patients with receptor-positive breast cancer. [ABSTRACT FROM AUTHOR]

Background: There exists evidence that body mass index (BMI) impacts on the efficacy of aromatase inhibitors in patients with breast cancer. The relationship between BMI and the efficacy of tamoxifen is conflicting. We investigated the impact of BMI on the efficacy of single tamoxifen and tamoxifen plus an aromatase inhibitor in the well-defined prospective study population of the ABCSG-06 trial.Methods: ABCSG-06 investigated the efficacy of tamoxifen vs tamoxifen plus aminoglutethimide in postmenopausal women with hormone receptor-positive breast cancer. Taking BMI at baseline, patients were classified as normal weight (BMI=18.5-24.9 kg m(-)(2)), overweight (BMI=25-29.9 kg m(-)(2)), and obese (30 kg m(-)(2)) according to WHO criteria.Results: Overweight+obese patients had an increased risk for distant recurrences (hazard ratio (HR): 1.51; Cox P=0·018) and a worse overall survival (OS; HR: 1·49; Cox P=0·052) compared with normal weight patients. Analysing patients treated with single tamoxifen only, no difference between overweight+obese patients and normal weight patients regarding distant recurrence-free survival (HR: 1.35; Cox P=0·24) and OS (HR: 0.99; Cox P=0·97) could be observed. In contrast, in the group of patients treated with the combination of tamoxifen plus aminoglutethimide, overweight+obese patients had an increased risk for distant recurrences (1.67; Cox P=0·03) and a worse OS (1.47; Cox P=0·11) compared with normal weight patients.Conclusion: BMI impacts on the efficacy of aromatase inhibitor-based treatment but not single tamoxifen. [ABSTRACT FROM AUTHOR]

Background:There exists evidence that body mass index (BMI) impacts on the efficacy of aromatase inhibitors in patients with breast cancer. The relationship between BMI and the efficacy of tamoxifen is conflicting. We investigated the impact of BMI on the efficacy of single tamoxifen and tamoxifen plus an aromatase inhibitor in the well-defined prospective study population of the ABCSG-06 trial.Methods:ABCSG-06 investigated the efficacy of tamoxifen vs tamoxifen plus aminoglutethimide in postmenopausal women with hormone receptor-positive breast cancer. Taking BMI at baseline, patients were classified as normal weight (BMI=18.5-24.9 kg m−2), overweight (BMI=25-29.9 kg m−2), and obese (30 kg m−2) according to WHO criteria.Results:Overweight+obese patients had an increased risk for distant recurrences (hazard ratio (HR): 1.51; Cox P=0·018) and a worse overall survival (OS; HR: 1·49; Cox P=0·052) compared with normal weight patients. Analysing patients treated with single tamoxifen only, no difference between overweight+obese patients and normal weight patients regarding distant recurrence-free survival (HR: 1.35; Cox P=0·24) and OS (HR: 0.99; Cox P=0·97) could be observed. In contrast, in the group of patients treated with the combination of tamoxifen plus aminoglutethimide, overweight+obese patients had an increased risk for distant recurrences (1.67; Cox P=0·03) and a worse OS (1.47; Cox P=0·11) compared with normal weight patients.Conclusion:BMI impacts on the efficacy of aromatase inhibitor-based treatment but not single tamoxifen. [ABSTRACT FROM AUTHOR]

Background: Concomitant intake of proton pump inhibitors (PPIs) may create drug-drug interactions, potentially impacting efficacy of anticancer agents. In the phase III PALLAS trial, the addition of palbociclib capsules to standard adjuvant endocrine therapy in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer did not improve invasive disease-free survival (iDFS). We explored whether concomitant use of PPIs affected survival outcomes in patients treated with palbociclib in PALLAS., Methods: This is an exploratory analysis of PALLAS including patients who received at least one dose of palbociclib capsules. We aimed to determine the association of concomitant PPI use with iDFS, distant relapse-free survival and overall survival. Uni- and multivariable Cox models with time-dependent PPI were used. The association between PPI use and neutropenia was also investigated., Results: Of 2840 patients treated with palbociclib + endocrine therapy, 525 (18.5%) had concomitant PPI and palbociclib intake. PPI intake was significantly associated with older age, post-menopausal status, use of aromatase inhibitors, higher body mass index, and worse Eastern Cooperative Oncology Group status (all P < 0.001). Concomitant PPI intake was not significantly associated with survival outcomes (iDFS, distant relapse-free survival, overall survival). All-grade neutropenia rates were numerically lower in patients who initiated a PPI before study start compared with patients never initiating PPIs (adjusted odds ratio 0.81, 95% confidence interval 0.60-1.09)., Conclusions: Our exploratory analysis did not demonstrate worse survival outcomes in patients receiving concomitant palbociclib and PPIs in PALLAS. Nonetheless, careful consideration of possible drug-drug interactions is important, especially when studying novel agents in the early breast cancer setting., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Monocytes comprise subsets of classical, intermediate and non-classical monocytes with distinct anti- or pro-tumor effects in breast cancer (BC). They are modulated by estrogen, and can contribute to BC control by endocrine therapy in preclinical models., Methods: To elucidate whether changes in monocyte subsets are associated with treatment and response, we investigated peripheral blood samples of 73 postmenopausal women with estrogen receptor (ER) positive BC, who received aromatase inhibitor therapy with or without the mucin-1 vaccine tecemotide in the ABCSG34 trial. Blood was retrieved at baseline, midterm and end of therapy, and was analyzed for the distribution and ER expression of monocyte subsets by flow cytometry., Results: When 40 healthy, age-matched women were compared with BC patients before treatment start, ER levels of monocytes did not differ, yet patients presented with a higher frequency of classical and fewer non-classical monocytes. Endocrine therapy triggered a significant increase in ER levels in all monocyte subsets, without affecting subset distribution. Vaccination had no overall impact on subset frequency and ER expression. Yet, a shift from intermediate to classical monocytes during therapy correlated with changes in plasma cytokines and chemokines and was significantly associated with low residual cancer burden in vaccinated patients. Without tecemotide, baseline ER levels in classical monocytes were significantly higher in women with good response to endocrine therapy., Conclusions: This study identified classical monocytes to be associated with ER positive BC and with patient response to neoadjuvant endocrine treatment and cancer vaccination., (© 2024. The Author(s).)

Background: Bidirectional crosstalk between HER2 and estrogen receptor (ER) pathways may influence outcomes and the efficacy of endocrine therapy (ET). Low HER2 expression levels (HER2-low) have emerged as a predictive biomarker in patients with breast cancer (BC)., Methods: PALLAS is an open, international, phase 3 study evaluating the addition of palbociclib for 2 years to adjuvant ET in patients with stage II-III ER-positive/HER2-negative BC. To assess the impact of HER2 expression on patient outcomes in the phase III PALLAS trial, we analyzed (1) the association between rate of HER2-low with demographic and clinicopathological parameters, (2) the prognostic value of HER2-low status on invasive disease-free survival (iDFS), distant relapse-free survival (DRFS), and overall survival (OS) and (3) HER2 expression's value as a predictive biomarker of response to palbociclib. HER2-low was defined as HER2 immunohistochemistry (IHC) 1 + or IHC 2 + with negative in situ hybridization (ISH). All pathologic evaluation was performed locally. Prognostic and predictive power of HER2 were assessed with Cox models., Results: From the original PALLAS intention-to-treat population (N = 5753), 5304 patients (92.2%) were included in this analysis. Among these, 2254 patients (42.5%) were classified as having HER2 IHC 0 (HER2-0), and 3050 (57.5%) as having HER2-low disease (1838 with IHC 1 + and 1212 with IHC 2 +). Median follow-up was 59.8 months. HER2-low prevalence varied significantly across 21 participating countries (range 16.7% to 75.6%; p < 0.001) and was more frequent in patients enrolled in North America (63.1%) than in Europe (53.4%) or other regions (53.4%) (p < 0.001). HER2 status was not significantly associated with iDFS in a multivariable Cox model (hazard ratio 0.93, 95% confidence interval 0.81 - 1.06). No significant interaction was observed between treatment arm and HER2 status for iDFS (p = 0.43). Similar results were obtained for DRFS and OS., Conclusions: In this large, prospective, global patient cohort, no differences were observed in clinical parameters, prognosis, or differential benefit from palbociclib between HER2-0 and HER2-low tumors. Significant geographic variability was observed in the prevalence of HER2-low status, suggesting a high degree of variation in pathologic assessment of HER2 expression without impact on outcomes., (© 2024. The Author(s).)

Purpose: The Clinical Treatment Score post-5 years (CTS5) is an easy-to-use tool estimating the late distant recurrence (LDR) risk in patients with hormone receptor-positive breast cancer after 5 years of endocrine therapy (ET). Apart from evaluating the prognostic value and calibration accuracy of CTS5, the aim of this study is to clarify if this score is able to identify patients at higher risk for LDR who will benefit from extended ET., Methods: Prognostic power, calibration, and predictive value of the CTS5 was tested in patients of the prospective ABCSG-06 and -06a trials (n = 1254 and 860 patients, respectively). Time to LDR was analyzed with Cox regression models., Results: Higher rates of LDR in the years five to ten were observed in high- and intermediate-risk patients compared to low-risk patients (HR 4.02, 95%CI 2.26-7.15, p < 0.001 and HR 1.93, 95%CI 1.05-3.56, p = 0.035). An increasing continuous CTS5 was associated with increasing LDR risk (HR 2.23, 95% CI 1.74-2.85, p < 0.001). Miscalibration of CTS5 in high-risk patients could be observed. Although not reaching significance, high-risk patients benefitted the most from prolonged ET with an absolute reduction of the estimated 5-year LDR of - 6.1% (95%CI - 14.4 to 2.3)., Conclusion: The CTS5 is a reliable prognostic tool that is well calibrated in the lower and intermediate risk groups with a substantial difference of expected versus observed LDR rates in high-risk patients. While a numerical trend in favoring prolonged ET for patients with a higher CTS5 was found, a significantly predictive value for the score could not be confirmed., Clinical Trial Registration: ABCSG-06 trial (NCT00309491), ABCSG-06A7 1033AU/0001 (NCT00300508)., (© 2024. The Author(s).)

Purpose: BMI affects breast cancer risk and prognosis. In contrast to cytotoxic chemotherapy, CDK4/6 inhibitors are given at a fixed dose, irrespective of BMI or weight. This preplanned analysis of the global randomized PALLAS trial investigates the impact of BMI on the side-effect profile, treatment adherence, and efficacy of palbociclib., Methods: Patients were categorized at baseline according to WHO BMI categories. Neutropenia rates were assessed with univariable and multivariable logistic regression. Time to early discontinuation of palbociclib was analyzed with Fine and Gray competing risk models. Unstratified Cox models were used to investigate the association between BMI category and time to invasive disease-free survival (iDFS). 95% CIs were derived., Results: Of 5,698 patients included in this analysis, 68 (1.2%) were underweight, 2,082 (36.5%) normal weight, 1,818 (31.9%) overweight, and 1,730 (30.4%) obese at baseline. In the palbociclib arm, higher BMI was associated with a significant decrease in neutropenia (unadjusted odds ratio for 1-unit change, 0.93; 95% CI, 0.91 to 0.94; adjusted for age, race ethnicity, region, chemotherapy use, and Eastern Cooperative Oncology Group at baseline, 0.93; 95% CI, 0.92 to 0.95). This translated into a significant decrease in treatment discontinuation rate with higher BMI (adjusted hazard ratio [HR] for 10-unit change, 0.75; 95% CI, 0.67 to 0.83). There was no significant improvement in iDFS with the addition of palbociclib to ET in any weight category (normal weight HR, 0.84; 95% CI, 0.63 to 1.12; overweight HR, 1.10; 95% CI, 0.82 to 1.49; and obese HR, 0.95; 95% CI, 0.69 to 1.30) in this analysis early in follow-up (31 months)., Conclusion: This preplanned analysis of the PALLAS trial demonstrates a significant impact of BMI on side effects, dose reductions, early treatment discontinuation, and relative dose intensity. Additional long-term follow-up will further evaluate whether BMI ultimately affects outcome.

Background: The widespread adoption of adjuvant bisphosphonate therapy for postmenopausal early breast cancer (EBC) patients was based on results of the Early Breast Cancer Trialist Group (EBCTCG) meta-analysis. Despite multiple regimens evaluated, there was no signal of varying efficacy with type, dose/dose intensity of bisphosphonate administration. We evaluated the effect of early treatment cessation using long-term outcome data from the ABCSG-12 trial., Patients and Methods: ABCSG-12 randomized 1803 hormone-receptor positive EBC patients on ovarian suppression between 1999 and 2006 to receive 4 mg zoledronic acid 6-monthly or not (and tamoxifen or anastrozole, 2:2 factorial design). In the current study, we evaluated whether the number of zoledronate infusions had an impact on breast cancer-specific outcomes. We hypothesized that amongst patients who received at least one zoledronate infusion, the number of infusions had no effect on outcomes. Time-to-event endpoints were analysed with Cox models and Kaplan Meier curves starting from a 3-year landmark. BMD analysis was restricted to patients who participated in the BMD sub-study., Results: 725 patients who received at least one zoledronate infusion were included in the time-to-event analysis. There was no statistically significant difference in disease-free or overall survival in the patients who received ≤6 zoledronate infusions (n = 170) compared to those who received ≥7 zoledronate infusions (n = 555)., Conclusions: Comparable to efforts to de-escalate treatment duration in metastatic bone disease, there was no evidence to indicate that a reduced number of zoledronate infusions is associated with reduced adjuvant efficacy. Further studies to define optimal regimens of adjuvant bone-targeted therapies are required., Competing Interests: Conflict of interest statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2022. Published by Elsevier Ltd. All rights reserved.)

BACKGROUND: Adjuvant aromatase inhibitors increase osteoporosis and fractures in patients with hormone receptor–positive breast cancer. We have previously reported outcomes of the ABCSG-18 (study 18 from the Austrian Breast & Colorectal Cancer Study Group) trial showing that adjuvant anti–receptor activator of nuclear factor-κB ligand denosumab treatment counteracts these adverse effects and may improve outcomes. We report here the final long-term outcomes. METHODS: ABCSG-18 is a prospective, double-blind, placebo-controlled, phase 3 trial in which 3425 postmenopausal patients with early hormone receptor–positive breast cancer receiving aromatase inhibitor therapy were randomly assigned in 58 trial centers to receive either denosumab 60 mg or placebo administered subcutaneously every 6 months. The primary end point was the time to first clinical fracture after randomization. Secondary disease outcome–related end points were disease-free survival (DFS), bone metastasis–free survival (BMFS), and overall survival (OS). RESULTS: For this final protocol-defined analysis, median follow-up is 8 years (interquartile range, 6 to 9.6 years). There were 309 versus 368 DFS events (hazard ratio, 0.83; 95% confidence interval [CI], 0.71 to 0.97) in the denosumab versus the placebo group, respectively, resulting in an absolute 9-year DFS benefit of 3.5 percentage points (79.4 vs. 75.9%). Adjuvant denosumab improved BMFS by 2.5 percentage points (88.9 vs. 86.4%; hazard ratio, 0.81; 95% CI, 0.65 to 1.00) and OS by 1.0 percentage point (90.9 vs. 89.9%; hazard ratio, 0.80; 95% CI, 0.64 to 1.01). No new toxicities for this dose of adjuvant denosumab were observed. CONCLUSIONS: DFS, BMFS, and OS continued to show benefit in this final long-term analysis of ABCSG-18. There were no new toxicities. (Funded by Amgen; ClinicalTrials.gov number, NCT00556374.)

Background: Associations between height, cancer risk and worse outcome have been reported for several cancers including breast cancer. We hypothesized that in breast cancer clinical trials, tall women should be overrepresented and might have worse prognosis., Methods: Data of 4,935 women, included from 1990 to 2010 in 5 trials of the Austrian Breast and Colorectal Cancer Study Group (ABCSG), were analyzed retrospectively. The primary objective was to determine differences in height distribution between the ABCSG cohort and the Austrian female population according to a cross-sectional health survey conducted by the Austrian Statistic Center in 2006 and 2007. Secondary endpoints were disease-free survival (DFS) and overall survival (OS) in different height classes and differences of body mass index (BMI) distribution., Results: Breast cancer patients in the ABCSG cohort were only slightly but statistically significantly smaller compared to unselected Austrian adult females (mean 164.3 vs. 164.8 cm; p < 0.0001) and significantly more patients were seen in the lower body height class (50 vs. 46%; p < 0.0001) when using the median as a cutoff. However, after adjustment for age, the difference in body height between the two cohorts was no longer significant ( p = 0.089). DFS and OS in the two upper height groups (≥170 cm) compared to the two lowest height groups (<160 cm) was not significantly different (5-year DFS: 84.7 vs. 83.0%; HR 0.91, 95% CI 0.73-1.13, p = 0.379; 5-year OS: 94.8 vs. 91.7%; HR 0.74, 95% CI 0.55-1.00, p = 0.051). The BMI of ABCSG patients was significantly higher than in the reference population (mean BMI 24.64 vs. 23.96; p < 0.0001)., Conclusions: Our results do not confirm previous findings that greater body height is associated with a higher breast cancer risk and worse outcome., Competing Interests: Verena Sagaster declares the following relations: Employment: none; Leadership: none; Stock or other Ownership: none; Honoraria: none; Consulting or Advisory Role: Bayer, Novartis, Eli Lilly; Speakers Bureau: none; Research Funding: none; Patents, Royalties, Other Intellectual Property: none; Expert Testimony: none; Travel, Accommodation, Expenses: none; Other Relationships: none. Florian Fitzal declares the following relations: Employment: none; Leadership: none; Stock or other Ownership: none; Honoraria: none; Consulting or Advisory Role: Pfizer, Roche; Speakers Bureau: none; Research Funding: Novartis, Pfizer, Roche, AstraZeneca, Comesa, Bondimed, Nanostring; Patents, Royalties, Other Intellectual Property: none; Expert Testimony: none; Travel, Accommodation, Expenses: Novartis, Pfizer, Roche, AstraZeneca, Comesa, Bondimed, Nanostring; Other Relationships: none. Yelena Devyatko declares the following relations: Employment: none; Leadership: none; Stock or other Ownership: none; Honoraria: none; Consulting or Advisory Role: none; Speakers Bureau: none; Research Funding: none; Patents, Royalties, Other Intellectual Property: none; Expert Testimony: none; Travel, Accommodation, Expenses: Roche; Other Relationships: none. Georg Pfeiler declares the following relations: Employment: none; Leadership: none; Stock or other Ownership: none; Honoraria: Amgen, Lilly, Roche, AstraZeneca, Novartis, Accord, Pfizer; Consulting or Advisory Role: Amgen, Lilly, Roche, AstraZeneca, Novartis, Accord, Pfizer; Speakers Bureau: none; Research Funding: none; Patents, Royalties, Other Intellectual Property: none; Expert Testimony: none; Travel, Accommodation, Expenses: none; Other Relationships: none. Michael Gnant declares the following relations: Employment: Snadoz; Leadership: none; Stock or other Ownership: none; Honoraria: Amgen, AstraZeneca, Celgene, Eli Lilly, Invectys, Pfizer, Nansotring, Novartis, Roche, Medison; Consulting or Advisory Role: AstraZeneca, Eli Lilly; Speakers Bureau: none; Research Funding: none; Patents, Royalties, Other Intellectual Property: none; Expert Testimony: none; Travel, Accommodation, Expenses: Amgen, AstraZeneca, Eli Lilly, Ipsen, Pfizer, Roche, Medison; Other Relationships: none. All other authors declare that they do not have any conflicts of interest in direct or indirect relationship with this research., (Copyright © 2021 by S. Karger AG, Basel.)

Purpose: Accurate response assessment during neoadjuvant systemic treatment (NST) poses a clinical challenge. Therefore, a minimally invasive assessment of tumor response based on cell-free circulating tumor DNA (ctDNA) may be beneficial to guide treatment decisions., Experimental Design: We profiled 93 genes in tissue from 193 patients with early breast cancer. Patient-specific assays were designed for 145 patients to track ctDNA during NST in plasma. ctDNA presence and levels were correlated with complete pathological response (pCR) and residual cancer burden (RCB) as well as clinicopathologic characteristics of the tumor to identify potential proxies for ctDNA release., Results: At baseline, ctDNA could be detected in 63/145 (43.4%) patients and persisted in 25/63 (39.7%) patients at mid-therapy (MT) and 15/63 (23.8%) patients at the end of treatment. ctDNA detection at MT was significantly associated with higher RCB (OR = 0.062; 95% CI, 0.01-0.48; P = 0.0077). Of 31 patients with detectable ctDNA at MT, 30 patients (96.8%) were nonresponders (RCB II, n = 8; RCB III, n = 22) and only one patient responded to the treatment (RCB I). Considering all 145 patients with baseline (BL) plasma, none of the patients with RCB 0 and only 6.7% of patients with RCB I had ctDNA detectable at MT, whereas 30.6% and 29.6% of patients with RCB II/III, respectively, had a positive ctDNA result., Conclusions: Overall, our results demonstrate that the detection and persistence of ctDNA at MT may have the potential to negatively predict response to neoadjuvant treatment and identify patients who will not achieve pCR or be classified with RCB II/III., (©2021 The Authors; Published by the American Association for Cancer Research.)

Purpose: The PALLAS study investigated whether the addition of palbociclib, an oral CDK4/6 inhibitor, to adjuvant endocrine therapy (ET) improves invasive disease-free survival (iDFS) in early hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer. In this analysis, we evaluated palbociclib exposure and discontinuation in PALLAS., Methods: Patients with stage II-III HR+, HER2- disease were randomly assigned to 2 years of palbociclib with adjuvant ET versus ET alone. The primary objective was to compare iDFS between arms. Continuous monitoring of toxicity, dose modifications, and early discontinuation was performed. Association of baseline covariates with time to palbociclib reduction and discontinuation was analyzed with multivariable competing risk models. Landmark and inverse probability weighted per-protocol analyses were performed to assess the impact of drug persistence and exposure on iDFS., Results: Of the 5,743 patient analysis population (2,840 initiating palbociclib), 1,199 (42.2%) stopped palbociclib before 2 years, the majority (772, 27.2%) for adverse effects, most commonly neutropenia and fatigue. Discontinuation of ET did not differ between arms. Discontinuations for non-protocol-defined reasons were greater in the first 3 months of palbociclib, and in the first calendar year of accrual, and declined over time. No significant relationship was seen between longer palbociclib duration or ≥ 70% exposure intensity and improved iDFS. In the weighted per-protocol analysis, no improvement in iDFS was observed in patients receiving palbociclib versus not (hazard ratio 0.89; 95% CI, 0.72 to 1.11)., Conclusion: Despite observed rates of discontinuation in PALLAS, analyses suggest that the lack of significant iDFS difference between arms was not directly related to inadequate palbociclib exposure. However, the discontinuation rate illustrates the challenge of introducing novel adjuvant treatments, and the need for interventions to improve persistence with oral cancer therapies., Competing Interests: Erica L. MayerConsulting or Advisory Role: Lilly, Novartis, AstraZeneca, Gilead SciencesResearch Funding: Pfizer (Inst) Christian FeslResearch Funding: Pfizer (Inst) Dominik HlauschekResearch Funding: Pfizer (Inst) Laura Garcia-EstevezConsulting or Advisory Role: Daiichi Sankyo/Astra Zeneca, Palex, Seattle GeneticsResearch Funding: Roche/Genentech (Inst) Nicholas ZdenkowskiHonoraria: Roche, Pfizer, EisaiConsulting or Advisory Role: Lilly, AstraZeneca, EisaiResearch Funding: Roche (Inst), Pfizer (Inst)Travel, Accommodations, Expenses: Roche, Amgen, Novartis Kathy D. MillerThis author is the Senior Deputy Editor of Journal of Clinical Oncology. Journal policy recused the author from having any role in the peer review of this manuscript.Consulting or Advisory Role: Merck, Genentech/Roche, Athenex, AstraZeneca, Bristol Myers Squibb/CelgeneResearch Funding: Taiho Pharmaceutical (Inst), Novartis (Inst), Seattle Genetics (Inst), Pfizer (Inst), Astex Pharmaceuticals (Inst), British Biotech (Inst), CytomX Therapeutics (Inst), Alphamab (Inst) Marija BalicConsulting or Advisory Role: Amgen, AstraZeneca, Daiichi Sankyo/Astra Zeneca, Lilly, MSD, Novartis, Pierre Fabre, Pfizer, Roche, SamsungSpeakers' Bureau: Amgen, AstraZeneca, Daiichi Sankyo/Astra Zeneca, Lilly, Novartis, Pierre Fabre, Pfizer, Roche, Seattle GeneticsResearch Funding: Lilly (Inst), Novartis (Inst), Pfizer (Inst)Travel, Accommodations, Expenses: MSD Ingrid A. MayerConsulting or Advisory Role: Novartis, AstraZeneca, Lilly, Genentech, GlaxoSmithKline, Immunomedics, Macrogenics, Pfizer, AbbVie, Seattle Genetics, Puma Biotechnology, Cyclacel, Blueprint Medicines, SanofiResearch Funding: Novartis (Inst), Pfizer (Inst), Genentech (Inst) David CameronConsulting or Advisory Role: Lilly (Inst), Novartis (Inst), Novartis (Inst), Research Triangle Institute RTI Health Solutions (Inst), Daiichi Sankyo (Inst), Prima BioMed (Inst), Merck Sharp & Dohme (Inst), Zymeworks (Inst), Eisai (Inst), Puma Biotechnology (Inst), Pfizer (Inst), Oncolytics (Inst), Roche (Inst), Roche (Inst), Samsung Bioepis (Inst), Seattle Genetics (Inst), Synthon (Inst), Clarity Pharmaceuticals (Inst), Bexon/Zymeworks (Inst), Sanofi (Inst)Research Funding: Roche (Inst), Novartis (Inst), AstraZeneca (Inst) Eric P. WinerHonoraria: Genentech/Roche, Genomic HealthConsulting or Advisory Role: Leap Therapeutics, Seattle Genetics, Jounce Therapeutics, GlaxoSmithKline, Carrick Therapeutics, Lilly, G1 Therapeutics, Syros Pharmaceuticals, Genentech/Roche, Gilead Sciences, Zymeworks, AthenexResearch Funding: Genentech (Inst)Other Relationship: InfiniteMD José Juan Ponce LorenzoHonoraria: Seattle Genetics, Novartis, Pfizer, AstraZeneca/Daiichi Sankyo, Lilly, RocheConsulting or Advisory Role: Seattle Genetics, Novartis, AstraZeneca/Daiichi Sankyo, Roche Tufia C. HaddadResearch Funding: Takeda (Inst) Hiroji IwataHonoraria: Chugai Pharma, AstraZeneca, Eisai, Pfizer, Daiichi Sankyo, Lilly Japan, Kyowa Hakko Kirin, Taiho PharmaceuticalConsulting or Advisory Role: Chugai Pharma, Daiichi Sankyo, Pfizer, AstraZeneca, Lilly Japan, Kyowa Hakko Kirin, NovartisResearch Funding: MSD (Inst), AstraZeneca (Inst), Kyowa Hakko Kirin (Inst), Daiichi Sankyo (Inst), Chugai Pharma (Inst), Nihonkayaku (Inst), Lilly Japan (Inst), Novartis (Inst), Bayer (Inst), Pfizer (Inst), Boehringer Ingelheim (Inst), Sanofi (Inst) Matthew GoetzConsulting or Advisory Role: Lilly, bioTheranostics, Genomic Health, Novartis, Eisai, Sermonix Pharmaceuticals, Context Therapeutics, Pfizer, BiovicaResearch Funding: Lilly (Inst), Pfizer (Inst), Sermonix Pharmaceuticals (Inst)Patents, Royalties, Other Intellectual Property: Methods and Materials for Assessing Chemotherapy Responsiveness and Treating Cancer, Methods and Materials for Using Butyrylcholinesterases to Treat Cancer, Development of Human Tumor Xenografts from Women with Breast Cancer Treated with Neoadjuvant Chemotherapy (Inst)Travel, Accommodations, Expenses: Lilly Fatima CardosoConsulting or Advisory Role: Roche, Novartis, Pfizer, AstraZeneca, Teva, Astellas Pharma, Merus, Celgene, Eisai, Daiichi Sankyo, Genentech, Merck Sharp & Dohme, Sanofi, Pierre Fabre, Macrogenics, Amgen, GE Healthcare, GlaxoSmithKline, Mylan, Mundipharma, Seattle Genetics, Samsung Bioepis, Medscape, Prime OncologyTravel, Accommodations, Expenses: Pfizer, Roche, AstraZeneca Tiffany A. TrainaConsulting or Advisory Role: Genentech/Roche, Pfizer, AstraZeneca, Merck, Puma Biotechnology, Athenex, Daiichi Sankyo, Ionis Pharmaceuticals, Seattle Genetics, Eisai, Exact Sciences, Foundation Medicine, Ayala Pharmaceuticals, Gilead Sciences, Blueprint Medicines, Ellipses Pharma, Fuji Pharma, ITeos Therapeutics, AgendiaResearch Funding: Eisai (Inst), Pfizer (Inst), Novartis (Inst), Innocrin Pharma (Inst), AstraZeneca (Inst), Astellas Pharma (Inst), Immunomedics (Inst), Genentech/Roche (Inst), Daiichi Sankyo (Inst), Carrick Pharm (Inst), Ayala Pharmaceuticals (Inst) Urs BreitensteinConsulting or Advisory Role: AstraZeneca (Inst), Elie Lilly (Inst), Novartis (Inst), Pierre Fabre (Inst), Roche (Inst) Kerstin AckerlResearch Funding: Pfizer (Inst) Otto Metzger FilhoHonoraria: Grupo Oncoclinicas, RocheResearch Funding: Susan G. Komen for the Cure (Inst), Pfizer (Inst), Roche/Genentech (Inst), Eisai (Inst), Cascadian Therapeutics (Inst), AbbVie (Inst)Travel, Accommodations, Expenses: Grupo Oncoclinicas Karin ZehetnerResearch Funding: Pfizer (Inst) Kadine SolomonEmployment: Alliance Foundation TrialsStock and Other Ownership Interests: Pfizer, Merck, Moderna Therapeutics Sarra El-AbedEmployment: Astellas Pharma (I), argenx (I)Research Funding: Novartis (Inst), Roche/Genentech (Inst), Pfizer (Inst) Kathy Puyana TheallEmployment: Pfizer (I)Stock and Other Ownership Interests: Pfizer (I)Honoraria: PfizerTravel, Accommodations, Expenses: Pfizer Dongrui Ray LuEmployment: PfizerStock and Other Ownership Interests: Pfizer Amylou DueckPatents, Royalties, Other Intellectual Property: Royalties from licensing fees for a patient symptom questionnaire (MPN-SAF) Michael GnantEmployment: Sandoz (I)Honoraria: Amgen, Novartis, AstraZeneca, LillyConsulting or Advisory Role: Daiichi-Sankyo, Veracyte, Tolmar, LifeBrain, Lilly Angela DeMicheleResearch Funding: Pfizer (Inst), Genentech (Inst), Calithera Biosciences (Inst), Novartis (Inst)No other potential conflicts of interest were reported.

Competing Interests: GP reports personal fees from Novartis, Roche, AstraZeneca, Eli Lilly, and Amgen; and grants and personal fees from Pfizer, outside the submitted Comment. AD reports grants from the Alliance Foundation for Clinical Trials, during the conduct of the study; personal fees from Pfizer and Context Therapeutics; grants from Novartis, Pfizer, Genentech, Calithera, and Johnson and Johnson, outside the submitted Comment; and that their spouse is on a data safety monitoring board for a Pfizer drug not for use in oncology. CF reports grants from Pfizer, during the conduct of the study. MG reports personal fees from Amgen, Daiichi Sankyo, AstraZeneca, Eli Lilly, LifeBrain, Nanostring, Novartis, and TLC Biopharmaceuticals, all outside the submitted Comment; and that an immediate family member is employed by Sandoz. ELM reports personal fees from Eisai, Eli Lilly, and Novartis, outside the submitted work. ACD declares no competing interests. We received support from Alliance Foundation Trials, Austrian Breast and Colorectal Cancer Study Group, and the Breast International Group. The trial (including these analyses) was funded by Pfizer, who provided the study drug and financial support.

Purpose: Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor-positive breast cancer has not been confirmed., Patients and Methods: In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer-free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival., Results: Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial., Conclusion: At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor-positive breast cancer., Competing Interests: Michael GnantEmployment: Sandoz (I)Honoraria: Amgen, Novartis, AstraZeneca, LillyConsulting or Advisory Role: Daiichi Sankyo, Veracyte, Tolmar¸ LifeBrain, Lilly Amylou C. DueckPatents, Royalties, Other Intellectual Property: Royalties from licensing fees for a patient symptom questionnaire (MPN-SAF) Miguel MartinHonoraria: Roche/Genentech, Lilly, Pfizer, Novartis, Pierre FabreConsulting or Advisory Role: Roche/Genentech, Novartis, Pfizer, Lilly, AstraZeneca, Taiho Pharmaceutical, PharmaMarSpeakers' Bureau: Lilly/ImClone, Roche/Genentech, Pierre FabreResearch Funding: Novartis (Inst), Roche (Inst)¸ Puma Biotechnology (Inst)Other Relationship: Roche, Novartis Hal J. BursteinThis author is an Associate Editor for Journal of Clinical Oncology. Journal policy recused the author from having any role in the peer review of this manuscript. Richard GreilHonoraria: Celgene, Roche, Merck, Takeda, AstraZeneca, Novartis, Amgen, Bristol Myers Squibb, MSD¸ Sandoz, AbbVie, Gilead Sciences, Daiichi SankyoConsulting or Advisory Role: Celgene, Novartis, Roche, Bristol Myers Squibb, Takeda, AbbVie, AstraZeneca, Janssen, MSD, Merck, Gilead Sciences, Daiichi SankyoResearch Funding: Celgene (Inst), Merck (Inst), Takeda (Inst), AstraZeneca (Inst), Novartis (Inst), Amgen (Inst), Bristol Myers Squibb (Inst), MSD (Inst), Sandoz (Inst), Gilead Sciences (Inst), Roche (Inst)Travel, Accommodations, Expenses: Roche, Amgen, Janssen-Cilag, AstraZeneca, Novartis, MSD, Celgene, Gilead Sciences, Bristol Myers Squibb, AbbVie, Daiichi Sankyo Antonio C. WolffThis author is an Associate Editor for Journal of Clinical Oncology. Journal policy recused the author from having any role in the peer review of this manuscript.Consulting or Advisory Role: Ionis PharmaceuticalsPatents, Royalties, Other Intellectual Property: A.C.W. has been named as an inventor on one or more issued patents or pending patent applications related to methylation in breast cancer, has assigned his rights to JHU, and participates in a royalty sharing agreement with JHUOpen Payments Link: https://openpaymentsdata.cms.gov/physician/357301/summary Arlene ChanHonoraria: Novartis, LillyConsulting or Advisory Role: LillyResearch Funding: Eisai Eric P. WinerHonoraria: Genomic Health, Genentech/RocheConsulting or Advisory Role: Leap Therapeutics, Seattle Genetics, Jounce Therapeutics, GlaxoSmithKline, Carrick Therapeutics, Lilly, G1 Therapeutics, Syros Pharmaceuticals, Genentech/Roche, Gilead Sciences, Zymeworks, AthenexResearch Funding: Genentech (Inst)Other Relationship: InfiniteMD Georg PfeilerHonoraria: Amgen, Roche/Genentech, Pfizer¸ Lilly, AstraZeneca/Merck, AstraZeneca/Daiichi Sankyo, Novartis, UCB, Accord HealthcareConsulting or Advisory Role: Pfizer¸ Amgen¸ Lilly, Novartis, AstraZeneca/Merck, AstraZeneca/Daiichi Sankyo, UCB, Roche/GenentechSpeakers' Bureau: Roche/Genentech, Pfizer, Lilly, Novartis, UCB, AstraZeneca/Merck, AstraZeneca/Daiichi Sankyo, Accord Healthcare, Amgen, Accord HealthcareResearch Funding: Pfizer, Roche/GenentechTravel, Accommodations, Expenses: Novartis, Lilly, Roche/Genentech, Lilly, AstraZeneca/Daiichi Sankyo Kathy MillerThis author is an Associate Editor for Journal of Clinical Oncology. Journal policy recused the author from having any role in the peer review of this manuscript.Consulting or Advisory Role: Merck, Genentech/Roche, Athenex, AstraZeneca, Bristol Myers Squibb/CelgeneResearch Funding: Taiho Pharmaceutical (Inst), Novartis (Inst), Seattle Genetics (Inst), Pfizer (Inst), Astex Pharmaceuticals (Inst), British Biotech (Inst), CytomX Therapeutics (Inst), Alphamab (Inst) Marco ColleoniResearch Funding: Roche (Inst) Gabor RubovskyConsulting or Advisory Role: Pfizer, Novartis, Roche, Gilead SciencesTravel, Accommodations, Expenses: Amgen Judith M. BlissResearch Funding: AstraZeneca (Inst), Merck Sharp & Dohme (Inst), Puma Biotechnology (Inst), Pfizer (Inst), Roche (Inst), GlaxoSmithKline/Novartis (Inst), Lilly (Inst), Janssen-Cilag (Inst), Clovis Oncology (Inst)Travel, Accommodations, Expenses: Pfizer Ingrid A. MayerConsulting or Advisory Role: Novartis, AstraZeneca, Lilly, Genentech, GlaxoSmithKline, Immunomedics, MacroGenics, Pfizer, AbbVie, Seattle Genetics, Puma Biotechnology, Cyclacel, Blueprint Medicines, SanofiResearch Funding: Novartis (Inst), Pfizer (Inst), Genentech (Inst) Christian SingerHonoraria: Novartis, AstraZeneca/MedImmune, Daiichi Sankyo Europe GmbHConsulting or Advisory Role: AstraZeneca/MedImmune, Daiichi-Sankyo, Gilead Sciences, Sanofi/Aventis, NovartisSpeakers' Bureau: Novartis, AstraZeneca/MedImmuneResearch Funding: Novartis, Sanofi, Myriad Genetics, Roche, AstraZeneca/MedImmuneTravel, Accommodations, Expenses: Roche, Novartis Zbigniew NoweckiTravel, Accommodations, Expenses: Roche/Genentech Olwen HahnLeadership: Via OncologyStock and Other Ownership Interests: Teleflex MedicalHonoraria: Cardinal Health (I)Consulting or Advisory Role: Pfizer, hmpglobal.comTravel, Accommodations, Expenses: Cardinal Health (I) Jacqui ThomsonHonoraria: MSD Oncology, Roche/Genentech Norman WolmarkOpen Payments Link: https://openpaymentsdata.cms.gov/physician/159597 Hope S. RugoHonoraria: Puma Biotechnology, MylanConsulting or Advisory Role: SamsungResearch Funding: MacroGenics (Inst), OBI Pharma (Inst), Eisai (Inst), Pfizer (Inst), Novartis (Inst), Lilly (Inst), Genentech (Inst), Merck (Inst), Immunomedics (Inst), Odonate Therapeutics (Inst), Daiichi Sankyo (Inst), Seattle Genetics (Inst), Sermonix Pharmaceuticals (Inst), AstraZeneca (Inst)Travel, Accommodations, Expenses: Pfizer, Novartis, Mylan, AstraZeneca Spain, MerckOpen Payments Link: https://openpaymentsdata.cms.gov/summary Guenther G. StegerHonoraria: Pfizer, Lilly, Novartis, Roche, AstraZeneca/Daiichi Sankyo, Teva, Pfizer, Lilly, NovartisTravel, Accommodations, Expenses: Roche, Teva Blanca Hernando Fernández de AránguizHonoraria: GlaxoSmithKline, PharmaMar, Clovis OncologyTravel, Accommodations, Expenses: Pfizer, MSD Oncology, Roche Tufia C. HaddadResearch Funding: Takeda (Inst) Meritxell Bellet EzquerraConsulting or Advisory Role: Pfizer, Lilly, NovartisSpeakers' Bureau: Lilly, Pfizer, Novartis Hannes FohlerEmployment: Takeda (I)Research Funding: Pfizer (Inst) Otto MetzgerHonoraria: Grupo Oncoclinicas, RocheResearch Funding: Susan G. Komen for the Cure (Inst), Pfizer (Inst), Roche/Genentech (Inst), Eisai (Inst), Cascadian Therapeutics (Inst), AbbVie (Inst)Travel, Accommodations, Expenses: Grupo Oncoclinicas Anita Jallitsch-HalperResearch Funding: Pfizer (Inst) Kadine SolomonEmployment: Alliance Foundation TrialsStock and Other Ownership Interests: Pfizer, Merck, Moderna Therapeutics Céline SchurmansResearch Funding: Pfizer (Inst), Roche/Genentech (Inst), AstraZeneca (Inst), Novartis (Inst), Servier (Inst), Pfizer (Inst), Sanofi (Inst)Patents, Royalties, Other Intellectual Property: My organization receives royalties from Agendia Kathy P. TheallEmployment: PfizerStock and Other Ownership Interests: PfizerHonoraria: PfizerTravel, Accommodations, Expenses: Pfizer Dongrui R. LuEmployment: PfizerStock and Other Ownership Interests: Pfizer Kathleen TennerStock and Other Ownership Interests: Merck Christian FeslResearch Funding: Pfizer (Inst) Angela DeMicheleResearch Funding: Pfizer (Inst), Genentech (Inst), Calithera Biosciences (Inst), Novartis (Inst) Erica L. MayerConsulting or Advisory Role: Lilly, Novartis, AstraZeneca, Gilead SciencesResearch Funding: Pfizer (Inst)No other potential conflicts of interest were reported.

Background: For postmenopausal women with hormone-receptor-positive breast cancer, the most effective duration for adjuvant therapy with an aromatase inhibitor remains unclear., Methods: In this prospective, phase 3 trial, we randomly assigned postmenopausal women with hormone-receptor-positive breast cancer who had received 5 years of adjuvant endocrine therapy to receive the aromatase inhibitor anastrozole for an additional 2 years (2-year group, receiving a total of 7 years) or an additional 5 years (5-year group, receiving a total of 10 years). The primary end point was disease-free survival. The primary analysis included all the patients who were still participating in the trial and who had no recurrence 2 years after randomization (i.e., when treatment in the 2-year group had ended). Secondary end points were overall survival, contralateral breast cancer, second primary cancer, and clinical bone fracture., Results: Among the 3484 women who were enrolled in the trial, 3208 remained in the trial without disease progression after the first 2 years of extended anastrozole treatment following randomization. Among these women, disease progression or death occurred in 335 women in each treatment group in the primary-analysis set at 8 years (hazard ratio, 0.99; 95% confidence interval [CI], 0.85 to 1.15; P = 0.90). No between-group differences occurred in most secondary end points, and subgroup analyses did not indicate differences in any particular subgroup. The risk of clinical bone fracture was higher in the 5-year group than in the 2-year group (hazard ratio, 1.35; 95% CI, 1.00 to 1.84)., Conclusions: In postmenopausal women with hormone-receptor-positive breast cancer who had received 5 years of adjuvant endocrine therapy, extending hormone therapy by 5 years provided no benefit over a 2-year extension but was associated with a greater risk of bone fracture. (Funded by AstraZeneca and the Austrian Breast and Colorectal Cancer Study Group; ABCSG-16/SALSA ClinicalTrials.gov number, NCT00295620.)., (Copyright © 2021 Massachusetts Medical Society.)