Real-World Data and Clinical Implications of Next-Generation Sequencing (NGS)-Based Analysis in Metastatic Breast Cancer Patients

Over the last two decades, the use of Next-Generation Sequencing (NGS) in medical oncology has increased the likelihood of identifying druggable mutations that may be potentially susceptible to targeted treatments. The European Society for Medical Oncology (ESMO) currently does not recommend the use of the NGS test to determine the therapeutic course of patients with metastatic breast cancer (mBC) in daily clinical practice. However, the aim of this work is to evaluate the potential contribution of the NGS test in selecting targeted therapies for patients with mBC. Data were retrospectively collected from 101 patients diagnosed with metastatic breast cancer and treated at the Modena Cancer Center between January 2015 and April 2022. A NGS test was performed on the tumor tissue of each patient at the Laboratory of Molecular Pathology of the University Hospital of Modena. This study analyzed the clinical-pathological characteristics and mutational profile of the population using NGS tests, with a focus on actionable mutations that could be targeted in advanced stages of clinical development. The indicator of this study was to quantify the actionable mutations that resulted in a change of cancer treatment. In total, 101 patients with metastatic breast cancer were analyzed, including 86 with luminal phenotype, 10 who were HER2-positive and 5 who were triple-negative. Median age was 52 years. NGS analysis was conducted on 47 samples of primary breast cancer, 52 on metastatic sites of disease and 2 on liquid biopsies. A total of 85 gene mutations were found. The most common mutations were identified in the PIK3CA (47%), FGFR (19%) and ERBB2 genes (12%), and to a lesser extent in other genes. Of the 61 patients with pathogenic mutations, 46 (75%) had at least one actionable mutation. Of these, nine received treatment with a molecular target drug: eight patients with a mutation of the PIK3CA gene were treated with alpelisib and fulvestrant; one patient with FGFR1/2 amplifications received TAS120. Median PFS for these patients was 3.8 months. The study results show that using the NGS test on cancer tissue of metastatic breast cancer could influence the therapeutic choices, considering the small sample size and limited follow-up. About 9% of the study population had their therapy modified based on the results of NGS. The growing number of detectable mutations and increased accessibility of the test may lead to a greater number of potential therapeutic implications for the NGS assay. Perspectives suggest that NGS analysis can be implemented in daily clinical practice, particularly in contexts where a Molecular Tumor Board (MTB) is active.

Thromboembolism and Adjuvant Endocrine Therapy (AET) in Hormone Receptor-Positive Early Breast Cancer (EBC): Did Treatment Evolution Change Incidence of the Adverse Event? A Meta-Analysis

The adjuvant endocrine therapy (AET) of HR+ EBC has been changing in recent years. Aromatase inhibitors (AIs) as an upfront strategy (or as part of a switch strategy) have been added to the choice of Tamoxifen (T) alone. Increased TE risk is well known in T-treated patients, while AIs have shown a reduced TE rate. By adding the cyclin dependent kinase 4/6 inhibitors (CDK4/6) to AIs, an increase in TE rate has been shown. We conducted this meta-analysis to evaluate the impact of the AETs on TE incidence. Twelve randomized phase III trials were included. Four trials evaluated the upfront strategy, 6 assessed the switch and 2 the combination with a CDK4/6 inhibitor. The new AETs did not significantly modify or affect the rate of TE events (OR 0.847, 95% CI, 0.528-1.366, P = .489). The OR for CDK4/6 inhibitor plus ET vs. ET was 3.635 (P = .002). Excluding the CDK4/6 inhibitors, the overall OR for AIs vs. T was 0.628 (P < .001), while it was 0.781 (P = .151) for switching T vs. continuing T for 5 years, and 0.52 (P < .0001) for the upfront strategies with AIs. The AIs alone or plus CDK4/6 inhibitors did not affect the rate of TE events. AIs as an upfront strategy is the safest AET, associated with the lowest TE incidence. The switch strategy increases TE rate, whereas the addition of CDK4/6 to the standard AET was shown to significantly increase TE events. The results of the currently ongoing trials with CDK4/6 inhibitors will help obtain additional data to evaluate any differences among the different CDK4/6 inhibitors and clarify the weight of TE adverse events in the benefit/risk balance of this new adjuvant strategy.

Adjuvant Endocrine Therapy in Premenopausal Women With Hormone Receptor-Positive Early-Stage Breast Cancer: Risk Stratification in a Real-World Setting

BACKGROUND

Ovarian function suppression (OFS) and hormone therapy (HT) represent an adjuvant option in premenopausal hormone receptor-positive early breast cancer (HR+EBC). The SOFT-TEXT trials showed improved outcomes upon receiving aromatase inhibitors (AIs)/OFS.

METHODS

In order to estimate the magnitude of absolute improvements, we conducted a retrospective study applying composite risk (CR) to 237 premenopausal HR+EBC patients.

RESULTS

Overall, 119 of these received tamoxifen (T)/OFS and 118 received AIs/OFS. The median age was 45 years (ys). After a median follow up of 65 months, recurrence was 6.7% in T patients and 10.2% in AI ones. CR (cutoff: 2.67) and ET duration (five-year cutoff) was found to have a significant impact on DFS. Invasive disease-free survival (IDFS) at 5 ys amounted to 82.9% for a CR>2.67 and 95% with CR

CONCLUSION

In a real-world setting, treatment options for premenopausal patients who are candidates for HT and OFS should take risk status into account. Therefore, every effort should be made to maintain patient adherence to treatment in order to manage toxicities and improve outcomes.

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Key Words

• Adjuvant hormone therapy
• Aromatase inhibitors
• Breast cancer
• Ovarian function suppression
• Tamoxifen

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Affiliation(s)

Raffaella D'Onofrio Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy
Claudia Omarini Division of Medical Oncology, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy; Gruppo Oncologico Italiano per la Ricerca Clinica (GOIRC), Parma, Italy
Angela Toss Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy; Department of Oncology and Hematology, Azienda Ospedaliero-Universitaria di Modena, Modena, Italy
Isabella Sperduti Biostatistics Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy
Federico Piacentini Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy; Gruppo Oncologico Italiano per la Ricerca Clinica (GOIRC), Parma, Italy
Monica Barbolini Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy
Laura Cortesi Division of Medical Oncology, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy
Elena Barbieri Division of Medical Oncology, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy
Elisa Pettorelli Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy
Chiara Chiavelli Department of Oncology and Hematology, Azienda Ospedaliero-Universitaria di Modena, Modena, Italy; Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
Massimo Dominici Division of Medical Oncology, Department of Medical and Surgical Sciences for Children and Adults, University Hospital of Modena, Modena, Italy; Department of Oncology and Hematology, Azienda Ospedaliero-Universitaria di Modena, Modena, Italy
Luca Moscetti Division of Medical Oncology, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy; Gruppo Oncologico Italiano per la Ricerca Clinica (GOIRC), Parma, Italy.

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Platinum-based chemotherapy and PARP inhibitors for patients with a germline BRCA pathogenic variant and advanced breast cancer (LATER-BC): retrospective multicentric analysis of post-progression treatments

INTRODUCTION

Patients with breast cancer (BC) harbouring a germinal BRCA pathogenic variant (gBRCA-PV) may have an enhanced sensitivity to platinum-based chemotherapy (PBC) and PARP inhibitors (PARPi). As reported in ovarian cancer, however, sensitivity and resistance to these treatments could partially overlap. In patients with a gBRCA-PV and advanced BC (aBC), it remains unclear whether prior exposure to PARPi/PBC affects tumour response to subsequent PBC/PARPi, respectively.

METHODS

We conducted a retrospective, multicentric study to investigate the clinical benefit of post-PBC PARPi and vice versa in patients with a gBRCA-PV and aBC. Patients included had received (neo)adjuvant PBC and then PARPi in advanced setting (group 1), PBC followed by PARPi (group 2) or PARPi followed by PBC (group 3), both in advanced setting. We reported median progression-free survival (mPFS) and disease control rate (DCR) in each group.

RESULTS

A total of 67 patients from six centres were included. PARPi-mPFS in advanced setting was 6.1 months in patients in group 1 (N = 12), while PARPi-DCR was 67%. In group 2 (N = 36), PARPi-mPFS was 3.4 months and PARPi-DCR was 64%. Age < 65 years and platinum-free interval (PFI) > 6 months were associated with longer PARPi-PFS; previous PBC-PFS > 6 months and PBC in first to second line were associated with longer PARPi-DCR. Patients in group 3 (N = 21) reported a PBC-mPFS of 1.8 months and a PBC-DCR of 14%. PARPi-PFS ≥ 9 months and PARPi-FI ≥ 6 months were associated with better PBC-DCR.

CONCLUSIONS

Sensitivity and resistance to PARPi and PBC partially overlap in patients with a gBRCA-PV and aBC. Evidence of PARPi activity emerged in patients who progressed on previous PBC.

Management of PALB2-associated breast cancer: A literature review and case report

Germline pathogenic variants (PV) of the PALB2 tumor suppressor gene are associated with an increased risk of breast, pancreatic, and ovarian cancer. In previous research, PALB2-associated breast cancer showed aggressive clinicopathological phenotypes, particularly triple-negative subtype, and higher mortality regardless of tumor stage, type of chemotherapy nor hormone receptor status. The identification of this germline alteration may have an impact on clinical management of breast cancer (BC) from the surgical approach to the systemic treatment choice. We herein report the case of a patient with a germline PV of PALB2, diagnosed with locally advanced PD-L1 positive triple-negative BC, who progressed after an immune checkpoint inhibitor (ICI)-containing regimen and then experienced a pathologic complete response after platinum-based chemotherapy. This case report hints a major role of the germline PALB2 alteration compared to the PD-L1 expression as cancer driver and gives us the opportunity to extensively review and discuss the available literature on the optimal management of PALB2-associated BC. Overall, our case report and review of the literature provide additional evidence that the germline analysis of PALB2 gene should be included in routine genetic testing for predictive purposes and to refine treatment algorithms.

Pathologic response and survival after neoadjuvant chemotherapy with or without pertuzumab in patients with HER2-positive breast cancer: the Neopearl nationwide collaborative study

Purpose

Clinical trials have shown a significant increase in pathologic complete response (pCR) with the addition of pertuzumab to neoadjuvant chemotherapy for patients with early-stage HER-2 positive breast cancer. To date, limited studies have examined comparative outcomes of neoadjuvant pertuzumab in real-world setting. The Neopearl study aimed to assess comparative real-life efficacy and safety of neoadjuvant pertuzumab for these patients.

Methods

We conducted a nationwide retrospective analysis involving 17 oncology facilities with a certified multidisciplinary breast cancer treatment committee. We identified patients with HER-2 positive stage II-III breast cancer treated with neoadjuvant chemotherapy based on trastuzumab and taxanes with or without pertuzumab. All patients underwent breast surgery and received a comprehensive cardiologic evaluation at baseline and after neoadjuvant treatment. Patients who received the combination of pertuzumab, trastuzumab, and chemotherapy constituted case cohort (PTCT), whereas those treated with trastuzumab and chemotherapy accounted for control cohort (TCT). The pCR rate and 5-year event free survival (EFS) were the primary outcomes. Secondary end-points were rates of conversion from planned modified radical mastectomy (MRM) to breast conservation surgery (BCS) and cardiotoxicities.

Results

From March 2014 to April 2021, we included 271 patients, 134 (49%) and 137 (51%) in TCT and PTCT cohort, respectively. Positive axillary lymph nodes and stage III were more frequent in PTCT cohort. The pCR rate was significantly increased in patients who received pertuzumab (49% vs 62%; OR 1.74, 95%CI 1.04-2.89) and with HER-2 enriched subtypes (16% vs 85%; OR 2.94, 95%CI 1.60-5.41). After a median follow-up of 5 years, the 5-year EFS was significantly prolonged only in patients treated with pertuzumab (81% vs 93%; HR 2.22, 95%CI 1.03-4.79). The same analysis performed on propensity score matched population showed concordant results. On univariate analysis, only patients with positive lymph nodes were found to benefit from pertuzumab for both pCR and 5-year EFS. The rates of conversion from MRM to BCS and cardiologic toxicities did not differ between the cohorts.

Conclusion

Our findings support previous data on improved outcomes with the addition of pertuzumab to trastuzumab-based neoadjuvant chemotherapy. This benefit seems to be more significant in patients with clinically positive lymph nodes.

Adjuvant capecitabine in triple negative breast cancer patients with residual disease after neoadjuvant treatment: real-world evidence from CaRe, a multicentric, observational study

Background

In triple negative breast cancer patients treated with neoadjuvant chemotherapy, residual disease at surgery is the most relevant unfavorable prognostic factor. Current guidelines consider the use of adjuvant capecitabine, based on the results of the randomized CREATE-X study, carried out in Asian patients and including a small subset of triple negative tumors. Thus far, evidence on Caucasian patients is limited, and no real-world data are available.

Methods

We carried out a multicenter, observational study, involving 44 oncologic centres. Triple negative breast cancer patients with residual disease, treated with adjuvant capecitabine from January 2017 through June 2021, were recruited. We primarily focused on treatment tolerability, with toxicity being reported as potential cause of treatment discontinuation. Secondarily, we assessed effectiveness in the overall study population and in a subset having a minimum follow-up of 2 years.

Results

Overall, 270 patients were retrospectively identified. The 50.4% of the patients had residual node positive disease, 7.8% and 81.9% had large or G3 residual tumor, respectively, and 80.4% a Ki-67 >20%. Toxicity-related treatment discontinuation was observed only in 10.4% of the patients. In the whole population, at a median follow-up of 15 months, 2-year disease-free survival was 62%, 2 and 3-year overall survival 84.0% and 76.2%, respectively. In 129 patients with a median follow-up of 25 months, 2-year disease-free survival was 43.4%, 2 and 3-year overall survival 78.0% and 70.8%, respectively. Six or more cycles of capecitabine were associated with more favourable outcomes compared with less than six cycles.

Conclusion

The CaRe study shows an unexpectedly good tolerance of adjuvant capecitabine in a real-world setting, although effectiveness appears to be lower than that observed in the CREATE-X study. Methodological differences between the two studies impose significant limits to comparability concerning effectiveness, and strongly invite further research.

Abstract OT2-01-07: evERA Breast Cancer: A phase III study of giredestrant (GDC-9545) + everolimus vs exemestane + everolimus in patients with estrogen receptor+, HER2– locally advanced or metastatic breast cancer

BACKGROUND Endocrine therapy (ET) modulates estrogen synthesis and/or estrogen receptor (ER) activity and is the mainstay of ER+ breast cancer (BC) treatment. ET + a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) is the standard of care in patients (pts) with ER+, HER2– metastatic BC (mBC) in the first-line setting. Fulvestrant ± a CDK4/6i, and everolimus + exemestane, are the current regimens approved for use in the second-line setting. However, therapeutic resistance to some ETs, such as aromatase inhibitors, can arise from ESR1 mutations driving estrogen-independent transcription and proliferation. Current post-CDK4/6i treatment options are suboptimal. New therapy options are therefore needed to reduce this risk and to improve outcomes, tolerability, quality of life, and adherence to treatment. Giredestrant is a highly potent, nonsteroidal oral selective ER antagonist and degrader (SERD) that achieves robust ER occupancy and is active regardless of ESR1 mutation status. While phase I SERD combination data in the post CDK4/6 setting is encouraging, there is no randomized combination data. Combining giredestrant and everolimus may potentially improve outcomes after CDK4/6is and in pts with ESR1-mutated tumors; evERA BC is investigating this combination to address the unmet need in the post-CDK4/6i setting. TRIAL DESIGN This phase III, global, randomized, open-label, multicenter study will evaluate the efficacy and safety of giredestrant + everolimus vs exemestane + everolimus in pts with ER+/HER2– locally advanced (LA)/mBC who had previous treatment with a CDK4/6i and ET in the LABC/mBC or adjuvant setting. Pts will be randomized to either giredestrant (30 mg) + everolimus (10 mg) by mouth (PO) every day (QD) on Days 1–28 of each 28-day cycle, or exemestane (25 mg) + everolimus (10 mg) PO QD on Days 1–28 of each 28-day cycle. Pts will receive treatment until disease progression or unacceptable toxicity. Pts will use a dexamethasone mouth rinse four times QD for 8 weeks, started concurrently with study treatment. ELIGIBILITY Female/male pts ≥18 years with ER+/HER2– LA/mBC, an Eastern Cooperative Oncology Group Performance Status of 0–1, measurable disease defined per RECIST v.1.1 (or evaluable bone metastases with at least one predominantly lytic bone lesion confirmed by computed tomography or magnetic resonance imaging), disease progression ≥6 months after initiating ET + CDK4/6i in the LABC/mBC setting (and ≥4 months on most recent ET, if ET + a CDK4/6i was not the most recent therapy received), or relapsed either while taking or within 12 months of exposure to combination adjuvant ET (≥12 months) and a CDK4/6i (≥6 months). Availability of a baseline blood sample to determine ESR1 mutation status by circulating tumor DNA assay for testing at a central laboratory. Men and pre-/perimenopausal women will receive a luteinizing hormone-releasing hormone agonist on Day 1 of each 28-day cycle. AIMS Primary endpoint: investigator-assessed progression-free survival (PFS; per RECIST v1.1). Secondary endpoints: investigator-assessed PFS in pts with detectable ESR1-mutated tumors in circulating tumor DNA at baseline; overall survival; objective response rate; duration of response; clinical benefit rate; patient-reported outcomes; safety; pharmacokinetics. STATISTICAL METHODS The primary endpoint analysis will use a stratified log-rank test at an overall 0.05 significance level (two-sided). An independent data monitoring committee will be in place for safety. ACCRUAL Target enrollment is 224 pts globally, and this study is currently recruiting. CONTACT INFORMATION For more information or to refer a patient, email global.rochegenentechtrials@roche.com or call 1-888-662-6728 (USA only). Clinicaltrials.gov number NCT05306340.

Citation Format: Erica L. Mayer, Sara Tolaney, Adam M. Brufsky, William Gradishar, Komal Jhaveri, Miguel Martín, Luca Moscetti, Gregory Vidal, Patricia Cortazar, Merilin Feldman, Bann-mo Day, Hope Rugo. evERA Breast Cancer: A phase III study of giredestrant (GDC-9545) + everolimus vs exemestane + everolimus in patients with estrogen receptor+, HER2– locally advanced or metastatic 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 OT2-01-07.

Targeting PI3K/AKT/mTOR Pathway in Breast Cancer: From Biology to Clinical Challenges

Breast cancer (BC) is the most common women cancer and cause of cancer death. Despite decades of scientific progress in BC treatments, the clinical benefit of new drugs is modest in several cases. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway mutations are frequent in BC (20-40%) and are significant causes of aggressive tumor behavior, as well as treatment resistance. Improving knowledge of the PI3K/AKT/mTOR pathway is an urgent need. This review aims to highlight the central role of PI3K-mTORC1/C2 mutations in the different BC subtypes, in terms of clinical outcomes and treatment efficacy. The broad base of knowledge in tumor biology is a key point for personalized BC therapy in the precision medicine era.

Predictive Role of CD36 Expression in HER2-Positive Breast Cancer Patients Receiving Neoadjuvant Trastuzumab

BACKGROUND

Despite huge efforts to identify biomarkers associated with long-term clinical outcomes in patients with early-stage HER2-positive breast cancer (HER2+ BC) treated with (neo)adjuvant anti-HER2 therapy, no reliable predictors have been identified so far. Fatty acid uptake, a process mediated by the transmembrane transporter CD36, has recently emerged as a potential determinant of resistance to anti-HER2 treatments in preclinical HER2+ BC models.

METHODS

Here, we investigated the association between baseline intratumor CD36 gene expression and event-free survival in 180 patients enrolled in the phase III trial Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimization (NeoALTTO), which randomly assigned stage II-III HER2+ BC patients to receive neoadjuvant lapatinib, trastuzumab, or lapatinib-trastuzumab in combination with chemotherapy. To this aim, we selected NeoALTTO trial patients for whom pretreatment whole transcriptomic data were available. The main study results were validated in an independent cohort of patients enrolled in the neoadjuvant phase II trial NeoSphere.

RESULTS

In 180 NeoALTTO patients, high intratumor CD36 expression was independently associated with worse event-free survival in patients treated with trastuzumab-based therapy (hazard ratio [HR] = 1.72, 95% confidence interval [CI] = 1.20 to 2.46), but not with lapatinib-based (HR = 1.02, 95% CI = 0.68 to 1.53) or trastuzumab-lapatinib-based (HR = 1.08, 95% CI = 0.60 to 1.94) therapy. Among 331 NeoSphere patients evaluated, high CD36 expression was independently associated with worse patient disease-free survival in both the whole study cohort (HR = 1.197, 95% CI = 1.002 to 1.428) and patients receiving trastuzumab-based neoadjuvant therapy (HR = 1.282, 95% CI = 1.049 to 1.568).

CONCLUSIONS

High CD36 expression predicts worse clinical outcomes in early-stage HER2+ BC treated with trastuzumab-based neoadjuvant therapy.

Predictive factors for relapse in triple-negative breast cancer patients without pathological complete response after neoadjuvant chemotherapy

Introduction

Triple-negative breast cancer (TNBC) patients who do not obtain pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) present higher rate of relapse and worse overall survival. Risk factors for relapse in this subset of patients are poorly characterized. This study aimed to identify the predictive factors for relapse in TNBC patients without pCR after NACT.

Methods

Women with TNBC treated with NACT from January 2008 to May 2020 at the Modena Cancer Center were included in the analysis. In patients without pCR, univariate and multivariable Cox analyses were used to determine factors predictive of relapse.

Results

We identified 142 patients with a median follow-up of 55 months. After NACT, 62 patients obtained pCR (43.9%). Young age at diagnosis (&lt;50 years) and high Ki-67 (20%) were signi!cantly associated with pCR. Lack of pCR after NACT resulted in worse 5-year event-free survival (EFS) and overall survival (OS). Factors independently predicting EFS in patients without pCR were the presence of multifocal disease [hazard ratio (HR), 3.77; 95% CI, 1.45–9.61; p=0.005] and residual cancer burden (RCB) III (HR, 3.04; 95% CI, 1.09–9.9; p=0.04). Neither germline BRCA status nor HER2-low expression were associated with relapse.

Discussion

These data can be used to stratify patients and potentially guide treatment decision-making, identifying appropriate candidates for treatment intensi!cation especially in neo-/adjuvant setting.

Role of Intrinsic Subtype Analysis with PAM50 in Hormone Receptors Positive HER2 Negative Metastatic Breast Cancer: A Systematic Review

Endocrine therapy (ET), associated with CDK 4/6 inhibitors, represents the first choice of treatment for HR+/HER2- metastatic breast cancer (mBC). Primary or secondary endocrine resistance could develop; however validated biomarkers capable of predicting such a conditions are not available. Several studies have shown that HR+/HER2- mBC comprises five intrinsic subtypes. The purpose of this systematic review was to analyze the potential correlations between intrinsic subtype, efficacy of treatment, and patient outcome. Five papers that analyzed the intrinsic subtype with PAM50 assay in patients (pts) with HR+/HER2- mBC treated with ET (alone or in combination) within seven phase III clinical trials (EGF30008, BOLERO-2, PALOMA-2,3, MONALEESA-2,3,7) were identified. Non-luminal subtypes are more frequent in endocrine-resistant pts and in metastatic sites (vs. primary tumors), have less benefit from ET, and worse prognosis. Among these, HER2-enriched subtypes are similar to HER2+ tumors and benefit from the addition of anti-HER2 agents (lapatinib) and, for less clear reasons, of ribociclib (unconfirmed data for palbociclib and everolimus). Basal-like subtypes are similar to triple-negative tumors, making them more sensitive to chemotherapy. The intrinsic subtype is also not static but can vary over time with the evolution of the disease. Currently, the intrinsic subtype does not play a decisive role in the choice of treatment in clinical practice, but has potential prognostic and predictive value that should be further investigated.

T-DM1 efficacy in trastuzumab-pertuzumab pre-treated HER2 positive metastatic breast cancer patients: a meta-analysis

Background

Current guidelines consider T-DM1 the standard 2^nd line therapy for HER2 positive metastatic breast cancer (MBC) patients following trastuzumab (T) + pertuzumab (P) and taxane 1^st line treatment. Despite this, there are no prospective studies supporting this sequence.

Methods

We performed a meta-analysis using real world data to determine the efficacy of T-DM1 after 1^st line TP in HER2 positive MBC patients. We used a random-effect model to find differences in the rate of 1-year progression free survival (PFS) between TP pre-treated population and the EMILIA phase III pivotal trial.

Results

Seven studies were eligible. The meta-analysis showed a combined 1-year PFS risk difference for T-DM1 efficacy after TP in 2^nd or more lines of -0.122, with lower and upper limits of -0.253 and 0.010, respectively (p = 0.07), with low heterogeneity among studies (I² 0.01%, p = 0.836). Considering the four studies on T-DM1 in 2^nd line setting, 1-year PFS risk was -0.034 (95% CI -0.207 – 0,139; p = 0.701) (I² 0.01%, p = 0.91).

Conclusion

Overall, the efficacy of T-DM1 after TP seems to be similar to that previously reported in the EMILIA trial. In the second line setting, data are not mature enough to confirm T-DM1 efficacy in TP pre-treated population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09556-7.

Palbociclib in a patient with HR+/HER2- advanced breast cancer and HIV1 infection: a case report

The use of drugs that affect the cell cycle represents one of the common strategies for the control of some unrelated pathologies, such as chronic viral HIV infections or cancer. The authors report the case of a patient followed for a hormone receptor-positive (HR+)/HER2 negative (HER2-) advanced breast cancer, treated with hormone therapy and CDK 4/6 inhibitors, and a concomitant HIV infection under antiretroviral treatment. The authors consider the function of the sterile alpha motif and HD domain-containing protein-1 (SAMHD1) enzyme, its implications in the control of viral replication and the correlation between its activity and the mechanism of action of the CDK 4/6 inhibitor palbociclib.

PANHER study: a 20-year treatment outcome analysis from a multicentre observational study of HER2-positive advanced breast cancer patients from the real-world setting

Background:

The evolution of therapeutic landscape of human epidermal growth factor receptor-2 (HER2)-positive breast cancer (BC) has led to an unprecedented outcome improvement, even if the optimal sequence strategy is still debated. To address this issue and to provide a picture of the advancement of anti-HER2 treatments, we performed a large, multicenter, retrospective study of HER2-positive BC patients.

Methods:

The observational PANHER study included 1,328 HER2-positive advanced BC patients treated with HER2 blocking agents since June 2000 throughout July 2020. Endpoints of efficacy were progression-free survival (PFS) and overall survival (OS).

Results:

Patients who received a first-line pertuzumab-based regimen showed better PFS (p < 0.0001) and OS (p = 0.004) than those receiving other treatments. Median PFS and mOS from second-line starting were 8 and 28 months, without significant differences among various regimens. Pertuzumab-pretreated patients showed a mPFS and a mOS from second-line starting not significantly affected by type of second line, that is, T-DM1 or lapatinib/capecitabine (p = 0.80 and p = 0.45, respectively). Conversely, pertuzumab-naïve patients receiving second-line T-DM1 showed a significantly higher mPFS compared with that of patients treated with lapatinib/capecitabine (p = 0.004). Median OS from metastatic disease diagnosis was higher in patients treated with trastuzumab-based first line followed by second-line T-DM1 in comparison to pertuzumab-based first-line and second-line T-DM1 (p = 0.003), although these data might be partially influenced by more favorable prognostic characteristics of patients in the pre-pertuzumab era. No significant differences emerged when comparing patients treated with ‘old’ or ‘new’ drugs (p = 0.43), even though differences in the length of the follow-up between the two cohorts should be taken into account.

Conclusion:

Our results confirmed a relevant impact of first-line pertuzumab-based treatment and showed lower efficacy of second-line T-DM1 in trastuzumab/pertuzumab pretreated, as compared with pertuzumab-naïve patients. Our findings may help delineate a more appropriate therapeutic strategy in HER2-positive metastatic BC. Prospective randomized trials addressing this topic are awaited.

Quality of life of therapies for hormone receptor positive advanced/metastatic breast cancer: Regulatory aspects and clinical impact in Europe

In recent years, the number of trials incorporating health-related quality of life (HRQoL) data has increased. The impact of HRQoL on regulatory decision making in the European context and on clinical practice is not well established. We conducted an analysis of the role of QoL data extracted from the clinical trials of the drugs approved for hormone receptor positive/HER2-negative advanced/metastatic breast cancer (mBC). The results from the HRQoL were collected and a meta-analysis was performed to evaluate the impact of experimental drugs compared to standard treatments. The results showed a non-detrimental effect in HRQoL from the new treatments. As regards the approval process, from an examination of the European Medicine Agency (EMA) documents, HRQoL was reported nonextensively and contained and discussed in the European assessment reports (EPARs) for eleven trials in the approval process and cited in three cases in the EPARs and summary of medicinal product characteristics (SmPC). An effort should be made by all the stakeholders to increase the visibility of the HRQoL results in order to allow increased consideration in the approval process to make QoL data more easily and visibly available for the clinician and the patients. The evaluation should be reflected in the SmPC in order to increase the amount of information provided to the physician.

Circulating and Intracellular miRNAs as Prognostic and Predictive Factors in HER2-Positive Early Breast Cancer Treated with Neoadjuvant Chemotherapy: A Review of the Literature

MicroRNAs (miRNA) are small noncoding RNAs that can act as both oncogene and tumor suppressors. Deregulated miRNA expression has been detected in human cancers, including breast cancer (BC). Considering their important roles in tumorigenesis, miRNAs have been investigated as potential prognostic and diagnostic biomarkers. Neoadjuvant setting is an optimal model to investigate in vivo the mechanism of treatment resistance. In the management of human epidermal growth factor receptor-2 (HER2)-positive early BC, the anti-HER2-targeted therapies have drastically changed the survival outcomes. Despite this, growing drug resistance due to the pressure of therapy is relatively frequent. In the present review, we focused on the main miRNAs involved in HER2-positive BC tumorigenesis and discussed the recent evidence on their predictive and prognostic value.

Thromboembolism (TE) and adjuvant endocrine therapy (AET) in hormone receptor positive (HR+) early breast cancer (EBC): Did the evolution of treatment change the incidence of the adverse event? A metanalysis

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Background: The AET of HR+ EBC has been changing in the recent years. Aromatase inhibitors (AI) as upfront, or in a planned switch strategy after Tamoxifen (T), have been added to the choice of T alone. An increased risk of TE is well known in the T treated patients while AIs have showed a reduced rate of TE. Recently, adding the cyclin dependent kinase 4/6 inhibitors (CDK4/6) abemaciclib to AIs, has showed a positive impact in the high risk HR+ EBC subgroups, but we are seeing an increase of the TE rate. We conducted this meta-analysis to evaluate the impact of the new AETs on the incidence of TE if compared to the standard monotherapy. Methods: We performed a meta-analysis of the randomized phase III trials comparing the experimental AETs and the endocrine standard therapy. A random-effect model to find differences in the rate of TE events between the experimental treatments and the standard therapy has been used. Results: Twelve phase III trials were included. Five trials evaluated the upfront strategy, 6 studies the switch and one the combination with a CDK4/6inhibitor (i.e. abemaciclib). Overall, the new AETs did not significantly modify or affect the rate of TE events (OR 0.708, 0.444-1.130, p = 0.148) with high heterogeneity among studies (I2 87, p < 0.0001). Excluding the abemaciclib trial, the incidence of TE is reduced (OR 0.609, 0.462-0.802, p < 0.0001) with a moderate heterogeneity among the studies (I2 59, p < 0.006). Considering the upfront strategies with AIs, the TE events are reduced (OR 0.507, 0.394-0.651, p < 0.0001) but they are not if we consider the trials in which T is used upfront before AIs (OR 0.762, 0.546-1.065, p = 0.112). Conclusions: Overall, the new treatments (AIs alone or plus CDK4/6 inhibitors) did not affect the rate in TE events. AIs as upfront strategy is the safest AETs of HR+ EBC, being associated to the lowest incidence of TE. The switch strategy increases the TE rate whereas the addition of abemaciclib to the standard AET showed to significantly increase the TE events. The results of the currently ongoing trials with the CDK4/6 inhibitors will help to obtain additional data to evaluate any differences among the different CDK4/6 inhibitors and to clarify the weight of the TE adverse events in the balance of benefit/risk of this new adjuvant strategy.

TDM-1 efficacy in trastuzumab-pertuzumab pre-treated HER2 positive metastatic breast cancer patients: A meta-analysis

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Background: Based on the results reported in Emilia trial population, current guidelines consider TDM-1 the standard second-line therapy for HER2 positive metastatic breast cancer (MBC) patients. Despite that, there are no prospective studies supporting the efficacy of TDM-1 following trastuzumab (T) + pertuzumab (P) and taxane first-line treatment. Currently, only real-world data have investigated this sequence with controversial results Methods: We performed a meta-analysis of the available real world data to determine the efficacy of TDM-1 after first-line TP in HER2 positive MBC patients. We used a random-effect model to find differences in the rate of 1-year progression free survival (PFS) between TP pre-treated population and the phase III Emilia trial (T pre-treated population). Results: Seven studies were eligible, in three of them data were from sub-group population analysis. The meta-analysis showed a combined 1-years PFS risk difference for TDM-1 efficacy after TP in second or more lines of -0.122, with lower and upper limits of -0.253 and 0.010, respectively (p=0.07) , with low heterogeneity among studies (I2 < 0.0001, p =0.836). Considering the four studies on TDM-1 in second-line setting, 1-years PFS risk was -0.034 (95% CI -0.207 – 0,139; p=0.701) (I2 < 0.0001, p =0.91). Conclusions: Results from the meta-analysis show that the efficacy of TDM-1 after TP double-block seems to be similar to the previously reported in Emilia trial. In the second line setting, available data are not mature enough to confirm TDM-1 efficacy in TP pre-treated population. Currently, TP pretreated patients should receive TDM-1 as indicated in the guidelines.

Carboplatin-Paclitaxel in triple-negative metastatic breast cancer during pregnancy with neoplastic thrombosis

The treatment of breast cancer diagnosed during pregnancy is a challenging situation for the patient, family and healthcare providers. Here we describe the case of a 35-year-old woman diagnosed with a triple-negative breast cancer relapse during pregnancy. She previously underwent neoadjuvant chemotherapy without any response, subsequent left skin sparing mastectomy plus axillary node dissection and radiation therapy to the chest wall and supraclavicular lymph nodes. Two years later, during her first single pregnancy, the patient presented a subclavian vein thrombosis and a BC relapse to locoregional lymph nodes. At 24 weeks of gestation, a first line treatment with weekly paclitaxel and carboplatin was started. Considering the disease progression after two complete cycles of chemotherapy, the patient had an elective caesarean section at 32+6 weeks. A full-body CT-scan and a PET-scan after the delivery showed a massive neoplastic thrombosis involving the left jugular, brachiocephalic and internal mammary vein, as well the superior vena cava and the right atrium. Few data are available on platinum-based chemotherapy during pregnancy in breast cancer patients. Nevertheless, the choice of therapy was conditioned by the previous absence of response to anthracycline and taxane. In case of breast cancer diagnosis during pregnancy, a multidisciplinary management as in the case described is recommended to increase the chance of survival both for the patients and their babies.

Impact of Baseline and On-Treatment Glycemia on Everolimus-Exemestane Efficacy in Patients with Hormone Receptor-Positive Advanced Breast Cancer (EVERMET)

PURPOSE

The mTOR complex C1 (mTORC1) inhibitor everolimus in combination with the aromatase inhibitor exemestane is an effective treatment for patients with hormone receptor-positive (HR⁺), HER2-negative (HER2^-), advanced breast cancer (HR⁺/HER2^- aBC). However, everolimus can cause hyperglycemia and hyperinsulinemia, which could reactivate the PI3K/protein kinase B (AKT)/mTORC1 pathway and induce tumor resistance to everolimus.

EXPERIMENTAL DESIGN

We conducted a multicenter, retrospective, Italian study to investigate the impact of baseline and on-treatment (i.e., during first 3 months of therapy) blood glucose levels on progression-free survival (PFS) in patients with HR⁺/HER2^- aBC treated with everolimus-exemestane.

RESULTS

We evaluated 809 patients with HR⁺/HER2^- aBC treated with everolimus-exemestane as any line of therapy for advanced disease. When evaluated as dichotomous variables, baseline and on-treatment glycemia were not significantly associated with PFS. However, when blood glucose concentration was evaluated as a continuous variable, a multivariable model accounting for clinically relevant patient- and tumor-related variables revealed that both baseline and on-treatment glycemia are associated with PFS, and this association is largely attributable to their interaction. In particular, patients who are normoglycemic at baseline and experience on-treatment diabetes have lower PFS compared with patients who are already hyperglycemic at baseline and experience diabetes during everolimus-exemestane therapy (median PFS, 6.34 vs. 10.32 months; HR, 1.76; 95% confidence interval, 1.15-2.69; P = 0.008).

CONCLUSIONS

The impact of on-treatment glycemia on the efficacy of everolimus-exemestane therapy in patients with HR⁺/HER2^- aBC depends on baseline glycemia. This study lays the foundations for investigating novel therapeutic approaches to target the glucose/insulin axis in combination with PI3K/AKT/mTORC1 inhibitors in patients with HR⁺/HER2^- aBC.

Second-line Eribulin in Triple Negative Metastatic Breast Cancer patients. Multicentre Retrospective Study: The TETRIS Trial

Introduction: Large and consistent evidence supports the use of eribulin mesylate in clinical practice in third or later line treatment of metastatic triple negative breast cancer (mTNBC). Conversely, there is paucity of data on eribulin efficacy in second line treatment. Methods: We investigated outcomes of 44 mTNBC patients treated from 2013 through 2019 with second line eribulin mesylate in a multicentre retrospective study involving 14 Italian oncologic centres. Results: Median age was 51 years, with 11.4% of these patients being metastatic at diagnosis. Median overall survival (OS) and progression free survival (PFS) from eribulin starting were 11.9 (95%CI: 8.4-15.5) and 3.5 months (95%CI: 1.7-5.3), respectively. We observed 8 (18.2%) partial responses and 10 (22.7%) patients had stable disease as best response. A longer PFS on previous first line treatment predicted a better OS (HR=0.87, 95%CI: 0.77-0.99, p= 0.038) and a longer PFS on eribulin treatment (HR=0.92, 95%CI: 0.85-0.98, p=0.018). Progression free survival to eribulin was also favorably influenced by prior adjuvant chemotherapy (HR=0.44, 95%CI: 0.22-0.88, p=0.02). Eribulin was generally well tolerated, with grade 3-4 adverse events being recorded in 15.9% of patients. Conclusions: The outcomes described for our cohort are consistent with those reported in the pivotal Study301 and subsequent observational studies. Further data from adequately-sized, ad hoc trials on eribulin use in second line for mTNBC are warranted to confirm our findings.

Two-month stop in mammographic screening significantly impacts on breast cancer stage at diagnosis and upfront treatment in the COVID era

Introduction

The present analysis aims to evaluate the consequences of a 2-month interruption of mammographic screening on breast cancer (BC) stage at diagnosis and upfront treatments in a region of Northern Italy highly affected by the severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) virus.

Methods

This retrospective single-institution analysis compared the clinical pathological characteristics of BC diagnosed between May 2020 and July 2020, after a 2-month screening interruption, with BC diagnosed in the same trimester of 2019 when mammographic screening was regularly carried out.

Results

The 2-month stop in mammographic screening produced a significant decrease in in situ BC diagnosis (−10.4%) and an increase in node-positive (+11.2%) and stage III BC (+10.3%). A major impact was on the subgroup of patients with BC at high proliferation rates. Among these, the rate of node-positive BC increased by 18.5% and stage III by 11.4%. In the subgroup of patients with low proliferation rates, a 9.3% increase in stage III tumors was observed, although node-positive tumors remained stable. Despite screening interruption, procedures to establish a definitive diagnosis and treatment start were subsequently carried out without delay.

Conclusion

Our data showed an increase in node-positive and stage III BC after a 2-month stop in BC screening. These findings support recommendations for a quick restoration of BC screening at full capacity, with adequate prioritization strategies to mitigate harm and meet infection prevention requirements.

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Due to the COVID19 pandemic, several mammographic screening services were disrupted.

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A 2-month stop in BC screening led to decreased in situ BC and increased node-positive and stage III BC diagnosis.

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A major impact was on the subgroup of patients with BC at high proliferation rates.

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Despite screening interruption, procedures to start treatments were subsequently carried out without delay.

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Restoration of BC screening at full capacity with infection prevention requirements is recommended.

Long-term outcome of pemetrexed maintenance for advanced nonsquamous non-small-cell lung cancer: a real-world observational cohort study

INTRODUCTION

Pemetrexed maintenance significantly improved progression-free survival (PFS) and overall survival (OS) in advanced nonsquamous non-small-cell lung cancer (NSCLC) patients not progressing after induction chemotherapy.

OBJECTIVES

This study is aimed at examine the association of various clinical factor and survival in a real-world cohort analysis.

MATERIALS AND METHODS

One hundred ninety-four patients were included and classified as "PM" cohort ("Pemetrexed Maintenance", including patients given with pemetrexed maintenance after induction chemotherapy, n=112), and "noPM" cohort ("no Pemetrexed Maintenance" including those discontinuing pemetrexed, n=82).

RESULTS

The median PFS was 8.8 and 5.4 months in the PM and noPM cohorts, respectively (p=0.001). The median OS was 19.6 months in the "PM" cohort and 13.2 months in the "noPM" cohort (p<0.02). In the multivariate analysis, ECOG Performance Status (PS) 0 and maintenance therapy were independently associated with improved PFS and OS. A longer median PFS was reported in patients given ≥5 cycles of pemetrexed maintenance (p<0.01).

DISCUSSION

These results further confirm the survival benefit of pemetrexed maintenance in a real-word population. All eligible advanced NSCLC patients should be strongly considered for at least 5 of pemetrexed maintenance.

The European Medicines Agency review of the initial application of atezolizumab and the role of PD-L1 expression as biomarker for checkpoint inhibitors

Immune checkpoint inhibitors have revolutionised cancer therapeutics. Translational research evaluating the role of biomarkers is essential to identify the ideal target population for these drugs. From a regulatory perspective, the identification of biomarkers and diagnostic assays is strongly encouraged by the European Medicines Agency (EMA). The aim of this article is to analyse the role of programmed death-ligand 1 (PD-L1) expression as a predictive biomarker in relation to the data submitted for the initial assessment of atezolizumab, a monoclonal antibody targeting human PD-L1. On 20 July 2017, atezolizumab was granted a marketing authorisation valid throughout the European Union (EU) for adult patients with (i) locally advanced or metastatic non-small-cell lung cancer (NSCLC) after chemotherapy and (ii) locally advanced or metastatic urothelial carcinoma (UC) after chemotherapy or cisplatin-ineligibility. Initially, these indications were not restricted by the level of PD-L1 expression, but preliminary data from an ongoing phase III trial in patients with UC led to a restriction in the UC indication to cisplatin-ineligible patients whose tumours have ≥5% PD-L1 expression. Still, the role of PD-L1 expression as predictive biomarker for atezolizumab therapy remains inconclusive and further research is needed. Data in this paper came from the scientific review leading to the initial regulatory approval of atezolizumab in the EU and its complementary application for indication (EMEA/H/C/004143/II/0010). The full scientific assessment report and product information are available on the EMA website (www.ema.europa.eu).

Loss of HER2 and decreased T-DM1 efficacy in HER2 positive advanced breast cancer treated with dual HER2 blockade: the SePHER Study

BACKGROUND

HER2-targeting agents have dramatically changed the therapeutic landscape of HER2+ advanced breast cancer (ABC). Within a short time frame, the rapid introduction of new therapeutics has led to the approval of pertuzumab combined with trastuzumab and a taxane in first-line, and trastuzumab emtansine (T-DM1) in second-line. Thereby, evidence of T-DM1 efficacy following trastuzumab/pertuzumab combination is limited, with data from some retrospective reports suggesting lower activity. The purpose of the present study is to investigate T-DM1 efficacy in pertuzumab-pretreated and pertuzumab naïve HER2 positive ABC patients. We also aimed to provide evidence on the exposure to different drugs sequences including pertuzumab and T-DM1 in HER2 positive cell lines.

METHODS

The biology of HER2 was investigated in vitro through sequential exposure of resistant HER2 + breast cancer cell lines to trastuzumab, pertuzumab, and their combination. In vitro experiments were paralleled by the analysis of data from 555 HER2 + ABC patients treated with T-DM1 and evaluation of T-DM1 efficacy in the 371 patients who received it in second line. Survival estimates were graphically displayed in Kaplan Meier curves, compared by log rank test and, when possibile, confirmed in multivariate models.

RESULTS

We herein show evidence of lower activity of T-DM1 in two HER2+ breast cancer cell lines resistant to trastuzumab+pertuzumab, as compared to trastuzumab-resistant cells. Lower T-DM1 efficacy was associated with a marked reduction of HER2 expression on the cell membrane and its nuclear translocation. HER2 downregulation at the membrane level was confirmed in biopsies of four trastuzumab/pertuzumab-pretreated patients. Among the 371 patients treated with second-line T-DM1, median overall survival (mOS) from diagnosis of advanced disease and median progression-free survival to second-line treatment (mPFS2) were 52 and 6 months in 177 patients who received trastuzumab/pertuzumab in first-line, and 74 and 10 months in 194 pertuzumab-naïve patients (p = 0.0006 and 0.03 for OS and PFS2, respectively).

CONCLUSIONS

Our data support the hypothesis that the addition of pertuzumab to trastuzumab reduces the amount of available plasma membrane HER2 receptor, limiting the binding of T-DM1 in cancer cells. This may help interpret the less favorable outcomes of second-line T-DM1 in trastuzumab/pertuzumab pre-treated patients compared to their pertuzumab-naïve counterpart.

Combinations in the first-line treatment of patients with advanced/metastatic renal cell cancer: regulatory aspects

The therapeutic landscape in the treatment of advanced/metastatic renal cell cancer has evolved over the last 2 years with the advent of immune checkpoint inhibitors. In 2018 and 2019, marketing authorisations valid throughout the European Union were issued for nivolumab and ipilimumab dual checkpoint inhibition and pembrolizumab or avelumab in combination with the tyrosine kinase inhibitor axitinib. These applications presented numerous regulatory challenges.In this paper, we summarise the main regulatory considerations, originating from the assessment of the dossiers submitted from the applicants for the three combinations. The regulatory issues are grouped in four sections: clinical pharmacology, efficacy, biomarkers and safety. In each section, we describe the issues raised during the regulatory evaluation performed by the Committee for Medicinal Products for Human Use (CHMP) assessors. The CHMP assessments determine whether the medicines concerned meet the necessary quality, safety and efficacy requirements, and whether the benefit-risk balance is positive.In summary, although the overall benefit-risk was considered positive for the three combinations, the immaturity of the outcome data and the absence of long-term safety data remain issues to be addressed. Postauthorisation efficacy studies have been required to confirm the effects of the new combinations.

Male mammary myofibroblastoma: Two case reports and brief review of literature

Myofibroblastoma of the breast is a rare benign stromal tumor that occurs in both sexes with a higher prevalence in male breast of older populations. Furthermore, myofibroblastoma can arise in extra mammary sites, along the milk-line. A variety of morphological variants in addition to the classic type have been identified. The differential diagnosis includes both benign and malignant entities that, through the use of clinical and radiological imaging, is difficult to characterize. Histopathological examination and immunohistochemistry are fundamental in the establishment of appropriate management of the disease and avoidance of overtreatment. The present study focuses on two cases of male mammary myofibroblastoma, with a short literature review.

Combined endocrine approaches vs endocrine therapy alone as first line treatment in elderly patients with hormone receptor-positive, HER2 negative, advanced breast cancer: to prescribe for the patient or the physician? A meta-analysis of phase II and III randomized clinical trials

Background

Elderly patients are underrepresented in clinical study where combined endocrine strategies were compared to endocrine therapy (ET) in hormone receptors positive, HER2 negative, metastatic breast cancer. The role of the new endocrine approaches in elderly women is still unclear.

Methods

We performed a meta-analysis of first line phase II/III randomized trials on ET versus combined strategies considering clinical benefit and safety profile. Trials with hazard ratio (HR) for PFS in elderly patients were included.

Results

Overall, the meta-analysis showed a PFS advantage for the experimental arms [HR 0.77, p 0.016] with a significant high/moderate heterogeneity [I2 65.46%, p 0.005]. For patients on CDK 4/6 inhibitors and ET, HR was 0.57 (p < 0.0001), with low heterogeneity [I2 0.0001%, p 0.96]. Hematological adverse events, as well as diarrhea with Abemaciclib, were significantly higher in elderly population.

Conclusions

The magnitude of PFS benefit due to the combined strategies in elderly patients is similar to those reported in the overall clinical trial population. Adding CDK4/6 inhibitors to ET significantly prolongs PFS, even if toxicity profile have to be carefully considered. Future trials should be designed taking into account patients’ age, geriatric assessment and comorbidity.

Abstract P1-19-43: Palbociclib-fulvestrant (PALBO-FUL) and everolimus -exemestane (EVE-EXE) for second line hormonal treatment (HT) of metastatic breast cancer (MBC) with lobular histology: A propensity score matched analysis

Background: Recently, CDK4/6i proved to improve the efficacy of HT of pts affected by luminal MBC. However, the best sequence of HT is still unclear and it is still uncertain if pts with lobular histology derive the same benefit of ductal when receiving second line CDK4/6i. Particularly in lobular MBC, the dysregulation of the AKTpathway with the overexpression of cyclin E potentially represents an important mechanism of acquired resistance to HT, finally providing an intrinsic resistance to subsequent CDK4/6i. Thus, a multicentric retrospective study was conducted to determine the efficacy of PALBO-FUL versus EVE-EXE as second line HT of MBC with Lobular histology.Methods: Pts affected by Lobular MBC receiving PALBO-FUL or EVE-EXE for second line HT from 2013 to 2018 in 6 Italian centers were considered eligible. The primary endpoint was progression free survival (PFS). A propensity score (PS) adjustment for baseline characteristics was further accomplished for survival analysis. Results: Seventy-four of 376 screened pts were diagnosed for Lobular MBC; 46pts received PALBO-FUL, whereas 28 were treated with EVE-EXE, without imbalance in clinical characteristics. PFS resulted to be significantly longer for pts receiving EVE-EXE in comparison with PALBO-FUL (6.1 vs. 4.5 months, HR 0.58, 95% CI 0.35-0.96; p=0.025). Previous chemotherapy exposure resulted to be significantly associated with PFS at the multivariate analysis (HR 0.41, 95% CI 0.24-0.72, p=0.002). At the PS analysis, adjusted for previous chemotherapy exposure and synchronous/metachronous metastatic status, PFS was confirmed to be significantly longer for pts receiving EVE-EXE in comparison with PALBO-FUL (6.0 vs. 4.6 months, p=0.04)Conclusion: This retrospective real-world analysis generates the hypothesis of a potential benefit of EVE-EXE in comparison with PALBO-FUL for second line HT of MBC with Lobular histology. Nevertheless, the small pts’ sample calls for a larger and adequately sized prospective validation. However, these data allow to speculate on the best hormonal therapeutic sequence in MLBC. Indeed, in this setting a late exposure to CDK4/6i might not allow to exploit its efficacy, while once hormonal resistance is acquired the inhibition of AKT/m-TOR pathway may represent the best option.

Citation Format: Armando Orlandi, Elena Iattoni, Laura Pizzuti, Agnese Fabbri, Andrea Botticelli, Carmela Di Dio, Antonella Palazzo, Giovanna Garufi, Giulia Indellicati, Daniele Alesini, Luisa Carbognin, Ida Paris, Angela Vaccaro, Luca Moscetti, Alessandra Cassano, Patrizia Vici, Valentina Magri, Giuseppe Naso, Diana Giannarelli, Paolo Marchetti, Emilio Bria, Giampaolo Tortora. Palbociclib-fulvestrant (PALBO-FUL) and everolimus -exemestane (EVE-EXE) for second line hormonal treatment (HT) of metastatic breast cancer (MBC) with lobular histology: A propensity score matched analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-43.

Impact of BMI on HER2+ metastatic breast cancer patients treated with pertuzumab and/or trastuzumab emtansine. Real-world evidence

Body mass index (BMI) is a main indicator of obesity and its association with breast cancer is well established. However, little is known in the metastatic setting, especially in HER2-positive patients. We assessed the influence of BMI on clinical outcomes of patients treated with pertuzumab and/or trastuzumab emtansine (T-DM1) for HER2+ metastatic breast cancer (mBC). BMI was addressed as a categorical variable, being classified on the basis of the following ranges, that is, 18.5-24.9, 25-29.9, and 30.0-34.9, namely, normal weight, overweight, and Class I obesity. The outcomes chosen were progression-free survival to first-line chemotherapy (PFS1) and overall survival (OS). Overall (N = 709), no impact of BMI was observed on PFS1 (p = .15), while BMI ≥ 30 was associated with worse OS (p = .003). In subjects who progressed to first line (N = 575), analyzing data across PFS1 quartiles and strata of disease burden, BMI predicted lower PFS1 in patients within the I PFS1 quartile and with the lowest disease burden (p = .001). Univariate analysis showed a detrimental effect of BMI ≥ 30 on OS for women within the I PFS1 quartile (p = .03). Results were confirmed in multivariate analysis. According to PFS1 quartiles a higher percentage of patients with high BMI and low disease burden progressed within 6 months of therapy. The effect of BMI on prognosis was also confirmed in multivariate analysis of OS for overall population. In our cohort, a BMI ≥ 30 correlated with worse OS in patients with HER2+ mBC who received pertuzumab and/or T-DM1 but had no impact on PFS to first line. BMI predicted worse I PFS1 quartile.

Predictive Role Of Body Composition Parameters In Operable Breast Cancer Patients Treated With Neoadjuvant Chemotherapy

Background

Fat tissue is strongly involved in BC tumorigenesis inducing insulin resistance, chronic inflammation and hormonal changes. Computed tomography (CT) imaging instead of body mass index (BMI) gives a reliable measure of skeletal muscle mass and body fat distribution. The impact of body composition parameters (BCPs) on chemosensitivity is still debated. We examined the associations between BCPs and tumor response to neoadjuvant chemotherapy (NC) in patients treated for operable breast cancer (BC).

Methods

A retrospective review of BC patients treated with NC in Modena Cancer Center between 2005 and 2017 was performed. BCPs, such as subcutaneous fat area (SFA), visceral fat area (VFA), lumbar skeletal muscle index (LSMI) and liver-to-spleen (L/S) ratio were calculated by Advance workstation (General Electric), software ADW server 3.2 or 4.7. BMI and BCPs were correlated with pathological complete response (pCR) and survival outcomes.

Results

407 patients were included in the study: 55% with BMI < 25 and 45% with BMI ≥ 25. 137 of them had pre-treatment CT scan imagines. Overweight was significantly associated with postmenopausal status and older age. Hormonal receptor positive BC was more frequent in overweight patients (p<0.05). Postmenopausal women had higher VFA, fatty liver disease and obesity compared to premenopausal patients. No association between BMI classes and tumor response was detected. High VFA and liver steatosis were negative predictive factors for pCR (pCR rate: 36% normal VFA vs 20% high VFA, p= 0.048; no steatosis 32% vs steatosis 13%, p=0.056). Neither BMI classes nor BCPs significantly influenced overall survival and relapse-free survival.

Conclusion

Visceral adiposity as well as steatosis were closely involved in chemosensitivity in BC patients treated with NC. Their measures from clinically acquired CT scans provide significant predictive information that outperform BMI value. More research is required to evaluate the relationship among adiposity site and survival outcomes.

Distinct HR expression patterns significantly affect the clinical behavior of metastatic HER2+ breast cancer and degree of benefit from novel anti-HER2 agents in the real world setting

We analyzed data from 738 HER2‐positive metastatic breast cancer (mbc) patients treated with pertuzumab‐based regimens and/or T‐DM1 at 45 Italian centers. Outcomes were explored in relation to tumor subtype assessed by immunohistochemistry (IHC). The median progression‐free survival at first‐line (mPFS1) was 12 months. Pertuzumab as first‐line conferred longer mPFS1 compared to other first‐line treatments (16 vs. 9 months, p = 0.0001), regardless of IHC subtype. Median PFS in second‐line (mPFS2) was 7 months, with no difference by IHC subtype, but it was more favorable with T‐DM1 compared to other agents (7 vs. 6 months, p = 0.03). There was no PFS2 gain in patients with tumors expressing both hormonal receptors (HRs; p = 0.17), while a trend emerged for tumors with one HR (p = 0.05). Conversely, PFS2 gain was significant in HRs‐negative tumors (p = 0.04). Median overall survival (mOS) was 74 months, with no significant differences by IHC subtypes. Survival rates at 2 and 3 years in patients treated with T‐DM1 in second‐line after pertuzumab were significantly lower compared to pertuzumab‐naïve patients (p = 0.01). When analyzed by IHC subtype, the outcome was confirmed if both HRs or no HRs were expressed (p = 0.02 and p = 0.006, respectively). Our results confirm that HRs expression impacts the clinical behavior and novel treatment‐related outcomes of HER2‐positive tumors when treatment sequences are considered. Moreover, multivariate analysis showed that HRs expression had no effect on PFS and OS. Further studies are warranted to confirm our findings and clarify the interplay between HER2 and estrogen receptor pathways in HER2‐positive (mbc) patients.

What's new?

About half of breast cancers positive for human epidermal growth factor (HER2) also express hormone receptors but the impact of hormone receptor status on the success of HER2‐directed treatments is not fully explored. Here the authors retrospectively assessed tumor behavior and treatment outcomes in 738 women with HER2+ metastatic breast cancer treated with new generation anti‐HER2 agents. Distinct hormone receptor expression patterns significantly affected the progression free and overall survival, justifying further studies to define optimal treatment regimens and the interplay between hormone receptor and HER2 signaling.

First-Line Treatment for Endocrine-Sensitive Bone-Only Metastatic Breast Cancer: Systematic Review and Meta-analysis

In the last decade, several clinical trials have investigated novel endocrine combinations for the first-line treatment of hormone receptor-positive metastatic breast cancer. Nevertheless, the use of combinations for the first-line treatment of bone-only disease is widely discussed as a result of its indolent natural history. We performed a comprehensive search of phase 3 randomized clinical trials published in the literature through September 2018. Our aim was to explore the role of the new endocrine approaches in bone-only metastatic breast cancer, suggesting a possible strategy for their selection. In particular, we evaluated the comparative risk of adverse event occurrence during these treatments. A total of 6 studies were deemed suitable for meta-analysis: the Monaleesa-2, Monaleesa-7, Monarch-3, Paloma-2, SWOG, and Alliance trials. Overall, the novel strategies were shown to improve progression-free survival in bone-only disease (hazard ratio = 0.65; 95% confidence interval, 0.49-0.86; P = .003). Combinations with cyclin-dependent kinase inhibitors improved progression-free survival (hazard ratio = 0.54; 95% confidence interval, 0.39-0.75; P < .001) with an acceptable toxicity profile. Abemaciclib was associated with increased anemia and gastrointestinal toxicity (especially diarrhea), whereas palbociclib was associated with increased leukopenia (but not neutropenia) compared to the other compounds. Increased aspartate aminotransferase levels were reported for both ribociclib and abemaciclib. The combination of cyclin-dependent kinase 4/6 inhibitors and endocrine therapy represents an effective and well-tolerated approach for first-line treatment in bone-only disease settings. Because no direct comparison between the 3 cyclin-dependent kinase 4/6 inhibitors is available, the selection of the most appropriate treatment should be based on toxicity profile as well as patient preference and copathologies.

Endocrine-based targeted combination versus endocrine therapy alone as first-line treatment in elderly patients with hormone receptor-positive advanced breast cancer: Meta-analysis of phase II and III randomized clinical trials

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Background: Combined endocrine approaches have been widely investigated as first-line treatment in hormone receptors positive metastatic breast cancer. In particular, multiple randomized trials showed that the addiction of CDK (cyclin-dependent kinase) 4/6 inhibitors to endocrine therapy (ET) increase progression free survival (PFS). Elderly patients (aged ≥65 years) are under represented in most of the clinical studies. Moreover, due to the multi-morbidity and the major toxicity associated with the targeted agents, the combination strategy in that subgroup is widely discussed. The present meta-analysis aimed to understand the role of the new endocrine approaches in women aged ≥65 years. Methods: This meta-analysis included first line phase II/III randomized published trials comparing (ET) to the experimental strategy. Trials with no data about hazard ratios (HR) for PFS in the subgroup of patients aged ≥65 years were excluded. The heterogeneity of the data was evaluated by Chi-square Q test and I2 statistic. Results: 8 studies were included in the analysis. 4 trials (Paloma1/TRIO-18, Paloma2, Monaleesa2, Monarch3) investigated the role of CDK 4/6 inhibitors, 2 trials (SWOG and FACT) analysed the combination of Fulvestrant plus Aromatase Inhibitors, while other two trials explored the association of ET with Bevacizumab (LEA) and Temsirolimus (HORIZON), respectively. Overall, the meta-analysis showed a PFS advantage for the experimental arms [HR 0.77, p 0.016] with a significant high/moderate heterogeneity [I2 65.46%, p 0.005]. The 4 studies adding CDK4/6 inhibitors to ET showed a significant improvement in PFS compared to ET alone. No significant advantages for the addition of anti-angiogenic agents or Fulvestrant to ET have been found in elderly population subgroup. Conclusions: The novel experimental combo-strategies in the first line setting showed an improvement in PFS in the subgroup of elderly patients. Adding CDK4/6 inhibitors to ET significantly prolongs PFS as compared to ET alone. The magnitude of PFS benefit due to addition of CDK4/6 inhibitors to ET is age-independent.

The unmet need for oncofertility preservation in women: Results of a survey by different oncological specialists in Lazio, Italy

In recent years, we have witnessed a growing interest in the prevention of the loss of reproductive efficacy in young women as a result of cancer or its treatments. Indeed, recent studies have shown that loss of fertility impacts deeply on young women and sometimes may be even more stressful than the cancer diagnosis itself. In fact, the risk of treatment-associated infertility and premature menopause is a major concern for patients. Nevertheless, the approach to fertility preservation in women diagnosed with cancer is far from being standardized, and counseling strategies are poorly adopted in clinical practice. In Italy, the federal structure of public health makes it difficult to refer patients to local referral centers experienced in fertility preservation. In particular, a need exists to identify oncologists in the Lazio region specialized in fertility preservation and those facilities who are able to counsel patients regarding their sexuality. For these reasons, the Lazio section of Italian Association of Medical Oncology has led an oncofertility and oncosexuality survey to assess deficiencies in the path to start fertility preservation procedures and to help patients with cancer-related sexual problems. In total, 273 healthcare providers participated in the survey. Overall, the participants had a low interest in their patients' infertility problems, which led to a poor referral of patients to fertility preservation centers. This behavior demonstrated by healthcare providers is attributed to the necessity to rapidly start oncological treatments, the lack of knowledge of referral centers, and the little experience in tackling the subject with the patients. The interviewees also recognize communication difficulties related to lack of information on issues, absence of rehabilitations paths, and embarrassment.

Abstract P1-18-06: First-line treatment for endocrine sensitive bone-only metastatic breast cancer: Is more always better?

The standard first-line for endocrine sensitive metastatic breast cancer (BC) is represented by endocrine therapy. Several phase III clinical trials searched for more effective endocrine strategies. Nevertheless, the use of combinations for the first-line treatment of bone-only disease (BoD) is widely discussed, due to its indolent course. Our meta-analysis aims to explore the role of new endocrine strategies in BoD.

A systematic review of electronic databases was conducted to identify the phase III clinical trials comparing the standard AI to novel experimental strategies. The hazard ratios (HR) for PFS were pooled in a meta-analysis. The heterogeneity of the data was evaluated by Chi-square Q test and I2 statistic.

8 studies were included in the analyses. 4 trials explored the role of CDK4/6 inhibitors (Monaleesa2 and 7, Monarch3 and Paloma2), 2 trials analyzed Fulvestrant + AI (SWOG and FACT), one trial studied Fulvestrant monotherapy (FALCON), while one trial evaluated the association between Bevacizumab and Letrozole (ALLIANCE). 6 trials reported data regarding the BoD, while 2 trials included the BoD in the non-visceral disease. Overall, the meta-analyses showed a PFS advantage for the experimental arms [HR 0.70 p 0.012], with a significant moderate/high heterogeneity [I2 66.48% p 0.004]. Only the FALCON and Paloma2 showed a significant improvement in PFS, respectively for Fulvestrant and Palbociclib + Letrozole. Considering only trials reporting data for BoD, the experimental arms significantly improved the PFS [HR 0.66 p 0.005], with a low/moderate non-significant heterogeneity [I2 44.95% p 0.106].

The novel strategies showed to be able to improve the PFS of BoD. Nonetheless, only Palbociclib + Letrozole provided statistically significant data of advantage in this setting. In clinical trials, BoD is often included in the non-visceral disease subgroup. Future clinical trials should take into account the differences in natural history and better prognosis of BoD, in order to define the best approach to these patients.

Citation Format: Toss A, Venturelli M, Sperduti I, Isca C, Molinaro E, Barbieri E, Piacentini F, Omarini C, Cortesi L, Cascinu S, Moscetti L. First-line treatment for endocrine sensitive bone-only metastatic breast cancer: Is more always better? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-18-06.

Abstract P4-13-07: SEQUERPLUS: A multicenter real practice observational study investigating the endocrine-based (E) therapies sequential approach in hormonal receptor positive (HR+) HER2 negative (-) metastatic breast cancer (MBC)

Background: Despite the sequential E therapy is recognized as the preferred approach for HR+/HER2- MBC, no data from clinical trials support the choice between the different sequential strategies.

Methods: In this retrospective study descriptive statistics are reported using the median (Interquartile range, IQR) or frequency. Progression Free Survival (PFS) curves were estimated with the Kaplan-Meier method and compared with the log-rank test. Analysis were performed by SPSS version 21.0 (SPSS Inc., Chicago, IL).

Results: From January 2006 to December 2017, 240 patients (pts) with HR+/HER2- MBC receiving at least two consecutive E therapies as first approach were selected from 12 italian cancer centers. The median age at the time of metastasis onset was 63.5 (IQR: 55-72.5) years; 184 (76.7%) pts were in menopausal status; 38 (16%) had de novo stage IV disease and the remaining 202 (84%) had recurrent BC with a median time of 78 months (5-396 months). At the beginning of MBC diagnosis, 148 (62%) pts had a single site of distant disease, 108 (45%) of whom had bone only disease and 45 (18.8%) presented visceral involvement too. The aromatase inhibitor (AI) was chosen as I-line therapy in 146 (60.9%) pts, followed by Fulvestrant (F) in 62 (25.8%) pts; the alternative I-line options were everolimus-exemestane (Eve-Exe), tamoxifene (T), Palbociclib (P)+AI and F+AI in 13 (5.4%), 14 (5.8%), 1 (0.4%) and 4 (1.7%) pts, respectively. The most favourite II-line option resulted F for 111 (46.2%) pts while the Eve-Exe combination was chosen in 70 (29.2%) pts, AI in 30 (12.5%) pts; T, AI+F, P+F and antiprogestincwere administered in 4 (1.7%), 4 (1.7%), 19 (7.9%) and 2 (0.8%) pts, respectively. For I and II-line, the AI followed by F (40%) and F followed by Eve-Exe (18%) were the most common sequential therapeutic approaches; the several alternative options were scanty used (in less than 10%). The median Progression-Free Survival (PFS) from first and second-line E therapies resulted 15.7 (95% CI 13.3-18.1) and 10.3 months (95% CI 8.7-11.9), respectively. Among 194 pts with disease progression after second-line E therapy, 87 (44.8%) received further E therapies with a median PFS 9.4 months (95% CI 7.9-10.9). The remaining 70 (29.2%) pts was treated with palliative chemotherapy. Interestingly, the median Overall Survival (OS) was even longer for pts receiving more lines of E therapies compared to the group with earlier introduction of chemotherapy (204.3 vs 92.8; p=0.007).

Finally, in the subgroup analyses a longer PFS benefit was observed in pts with disease recurrence over 12 months from initial diagnosis (38.1 vs 30.3 months p=0.04) and limited sites of disease involvement at the time of MBC diagnosis (37.6 vs 28.3 months, p=0.03)

Conclusions: The sequential use in first and second-line setting of E therapies for HR+/HER2- MBC improves median PFS up to 32.3 months. According to real practice experience the optimal sequences could be AIs followed by F and F followed by Eve-Exe. A role for these compounds should be redefined in the light of recently introduction of CDK 4/6 inhibitors in combination with AIs or F for the first or later lines.

Citation Format: Fabi A, Giannarelli D, Botticelli A, Scagnoli S, Pellegrino A, Fabbri A, Corsi D, Magri V, Pizzuti L, Paris I, Bruni V, Pace R, Lanzetta G, Stani S, Moscetti L, Marchetti P, Piesco G, Cognetti F, Rossi V. SEQUERPLUS: A multicenter real practice observational study investigating the endocrine-based (E) therapies sequential approach in hormonal receptor positive (HR+) HER2 negative (-) metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-13-07.

Differential molecular pathways expression in HER2 positive early breast cancer according to hormone receptor status

PURPOSE

Hormone receptors (HR) status in HER2 + breast cancer (BC) is a recognized stratification factor with relevant clinical implication. According to HR expression, HER2 + BC show different clinical characteristics, treatment sensitivity and prognosis. The interaction between HR and HER2 pathways remains incompletely understood.

METHODS

Thirty-four HER2 + BC were included: 18 tumors with HER2+/HR + and 16 with HER2+/HR-. The expression of 770 genes and 13 molecular pathways were evaluated using Nanostring PanCancer Pathway panel performed on FFPE BC biopsies.

RESULTS

Gene expression analysis identified 127 genes with significantly different expression between the two cohorts. 83% of these genes were overexpressed in HER2+/HR- cohort. Globally, 23% of them belonged to PI3K pathway (41 genes), 15% to Trascriptional regulation (26 genes) and 12% to MAPK (22 genes). Regarding pathway expression, PI3K, MAPK and NOTCH were significantly differently expressed between the two groups (p = 0.003, p = 0.0018 and p = 0.02, respectively), all of them were overexpressed in HER2+/HR- tumors.

CONCLUSIONS

According to HR status, HER2 + tumors express different pathways profiles: the overexpression of PI3K, MAPK and NOTCH pathways in HER2+/HR- group could justify different survival outcomes and treatment sensitivity. The identification of tumor driver pathways may be a useful instrument for individualized pathway-directed therapies. Further clinical implications are warranted.

Palbociclib plus endocrine therapy in HER2 negative, hormonal receptor-positive, advanced breast cancer: A real-world experience

Data from 423 human epidermal growth factor receptor 2-negative (HER2-), hormone receptor-positive (HR+) advanced breast cancer (aBC) patients treated with palbociclib and endocrine therapy (ET) were provided by 35 Italian cancer centers and analyzed for treatment outcomes. Overall, 158 patients were treated in first line and 265 in second/later lines. We observed 19 complete responses and 112 partial responses. The overall response rate (ORR) was 31% (95% confidence interval [CI], 26.6-35.4) and clinical benefit was 52.7% (95% CI, 48-57.5). ORR was negatively affected by prior exposure to everolimus/exemestane ( p = 0.002) and favorably influenced by early line-treatment ( p < 0.0001). At 6 months, median progression-free survival was 12 months (95% CI, 8-16) and median overall survival was 24 months (95% CI, 17-30). More favorable outcomes were associated with palbociclib in early lines, no visceral metastases and no prior everolimus/exemestane. The main toxicity reported was neutropenia. Our results provide further support to the use of palbociclib with ET in HER2-, HR+ aBC. Differences in outcomes across patients subsets remain largely unexplained.