Gender minorities in breast cancer - Clinical trials enrollment disparities: Focus on male, transgender and gender diverse patients

BACKGROUND

The last years have seen unprecedented improvement in breast cancer (BC) survival rates. However, this entirely apply to female BC patients, since gender minorities (male, transgender/gender-diverse) are neglected in BC phase III registration clinical trials.

METHODS

We conducted a scoping review of phase III clinical trials of agents with a current positioning within the therapeutic algorithms of BC.

RESULTS

We selected 51 phase III trials. Men enrollment was allowed in 35.3% of trials. In none of the trial inclusion/exclusion criteria referred to transgender/gender-diverse people. A numerical higher rate of enrolled men was observed in the contemporary as compared to historical group. We found a statistically significant association between the drug class and the possibility of including men: 100%, 80%, 50%, 33.3%, 25%, 10% and 9.1% of trials testing ICI/PARP-i, ADCs, PI3K/AKT/mTOR-i, anti-HER2 therapy, CDK4/6-i, ET alone, and CT alone. Overall, 77409 patients were enrolled, including 112 men (0.2%). None of the trial reported transgender/gender-diverse people proportion. Studies investigating PARP-i were significantly associated with the highest rate of enrolled men (1.42%), while the lowest rates were observed for trials of CT (0.13%), ET alone (0.10%), and CDK 4/6-I (0.08%), p < 0.001.

CONCLUSIONS

We confirmed that gender minorities are severely underrepresented among BC registration trials. We observed a lower rate of men in trials envisaging endocrine manipulation or in less contemporary trials. This work sought to urge the scientific community to increase the awareness level towards the issue of gender minorities and to endorse more inclusive criteria in clinical trials.

Breaking barriers in triple negative breast cancer (TNBC) - Unleashing the power of antibody-drug conjugates (ADCs)

Antibody-drug conjugates (ADCs) represent a novel class of molecules composed of a recombinant monoclonal antibody targeted to a specific cell surface antigen, conjugated to a cytotoxic agent through a cleavable or non-cleavable synthetic linker. The rationale behind the development of ADCs is to overcome the limitations of conventional chemotherapy, such as the narrow therapeutic window and the emergence of resistance mechanisms. ADCs had already revolutionized the treatment algorithm of HER2-positive breast cancer. Currently, emergent non-HER2 targeted ADCs are gaining momentum, with special focus on triple-negative disease therapeutic landscape. Sacituzumab govitecan (SG) is an ADC consisting of a humanized monoclonal antibody hRS7 targeting trophoblast cell surface antigen 2 (Trop2), linked to the topoisomerase I inhibitor SN-38 by a hydrolysable linker. It currently stands as the only non-HER2 targeted ADC that already received approval for the treatment of unresectable locally advanced or metastatic triple negative breast cancer (TNBC) in patients who had received two or more prior systemic therapies, with at least one for advanced disease. The purpose of these review is to analyze the available evidence regarding ADCs in TNBC, alongside with providing an overview on the ongoing and future research horizons in this field.

Central obesity, body mass index, metabolic syndrome and mortality in Mediterranean breast cancer patients

Obesity and metabolic disorders have been associated with poor outcomes in non-Mediterranean breast cancer (BC) patients. The purpose of this study was to investigate the prognostic potential of anthropometric variables in patients with early BC living in Southern Mediterranean region of Italy. We enrolled 955 consecutive early BC patients treated in hospitals in Naples between 2009 and 2013 (median follow-up 11.8-year ending 15/09/2022). Body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and metabolic syndrome (MetS) were collected. All-cause and BC-specific mortality were calculated. At the last day of contact 208 (22%) patients had died, 131 (14%) from BC. High WC (≥ 88 cm) or WHR (> 0.85) and the MetS were significantly associated with moderately increased risk of all-cause mortality (HR=1.39, 1.62, 1.61, respectively). A significant increased risk of BC-specific mortality was found in obese patients, in those with high WC, high WHR and those with MetS (HR=1.72, 1.71, 1.80, 1.81, respectively). Central obesity significantly increased total and BC-specific mortality particularly in pre-menopausal women and in luminal subtypes, while in post-menopause MetS was a stronger risk factor. Obesity and MetS may impair the effectiveness of BC therapies hence active lifestyle interventions are encouraged.

Evolving treatments and outcomes in HER2-Positive metastatic breast cancer: Data from the GIM14/BIOMETA study

BACKGROUND

Treatment for HER2-positive (+) metastatic breast cancer has improved in the last decade. We analyzed treatment changes over time and their impact on patients outcomes in a real-world dataset.

METHODS

Data from 637 HER2+ patients with metastatic breast cancer enrolled in the multicenter Italian GIM14/BIOMETA study were retrieved. Progression-free survival (PFS) over time was evaluated according to the type of anti-HER2 therapy, disease onset (de novo vs. relapsing), metastatic site, and year of treatment (2000-2013 vs. 2014-2020).

RESULTS

Median follow-up was 64.4 months. Overall, for first-line therapies, mPFS was 16.5 vs 19.5 months for patients treated in 2000-2013 vs 2014-2020 (HR: 0.78, 95% CI:0.65-0.94, P = 0.008). mPFS improved over time in all patients except for those with brain metastasis. Interestingly mPFS was 17.4 vs13.4 months (HR, 1.49; 95% CI, 1.13-1.98, P = 0.005) in 2000-2013 and 24.4 vs 20.9 months (HR 1.04; 95% CI 0.78-1.40 p = 0.77) in 2014-2020 in pts without vs with liver metastases. For second line therapies, the overall median PFS was 9.6 months (95% CI, 8.31-10.97) and did not change over time.

CONCLUSION

Median first-line PFS improved since 2014, mainly due to the introduction of pertuzumab. The outcome of patients with liver metastases appears to have improved in recent years. Patients with brain metastases had the worst PFS, which also did not improve over time.

Discontinuation rate and serious adverse events of chemoimmunotherapy as neoadjuvant treatment for triple-negative breast cancer: a systematic review and meta-analysis

BACKGROUND

The use of combination of chemotherapy with immune checkpoint inhibitors (ICIs) has shown efficacy in triple-negative breast cancer (TNBC), and chemoimmunotherapy has been introduced in clinical practice. However, limited data are available on the discontinuation rate and serious adverse events of these treatments, particularly in the neoadjuvant setting. Herein, we carried out a comprehensive systematic review and meta-analysis to assess discontinuation rate and serious adverse events of chemoimmunotherapy compared to chemotherapy alone in phase II and III neoadjuvant clinical trials in TNBC.

MATERIALS AND METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, EMBASE, Cochrane Library, and PubMed/Medline were searched for articles published from June 2008 to May 2023. The outcomes of interest were the discontinuation rate, serious adverse events, and grade 3-4 adverse events.

RESULTS

Four studies were included in the analysis. The pooled odds ratios (ORs) for discontinuation rate and serious adverse events were 1.26 [95% confidence interval (CI) 0.78-2.06] and 1.79 (95% CI 1.4-2.28), respectively, in patients receiving chemoimmunotherapy compared to chemotherapy alone as neoadjuvant treatment for TNBC. The chemoimmunotherapy group had a higher risk of grade 3-4 adverse events (OR 1.30, 95% CI 1.07-1.59). The analysis showed substantial heterogeneity, and the risk of discontinuation rate was heavily influenced by the KEYNOTE-522 trial.

CONCLUSIONS

Our findings highlight the need for clinical trials specifically focused on safety, quality of life, and treatment adherence in TNBC patients receiving neoadjuvant treatment. Close monitoring of tolerability remains crucial in this clinical setting.

Tucatinib's journey from clinical development to clinical practice: New horizons for HER2-positive metastatic disease and promising prospects for brain metastatic spread

Approximately 20% of breast cancers (BCs) overexpress human epidermal growth factor receptor 2 (HER2), a transmembrane glycoprotein with tyrosine kinase activity, encoded by ERBB2 gene. Historically, HER2 overexpression has been linked with increased disease recurrence and a worse prognosis. However, the increasing availability of different anti-HER2 compounds and combinations is progressively improving HER2-positive BC outcome, thus requiring expertise to prioritize both overall survival (OS) prolongation and quality of life, without neglecting the accessibility to further treatment lines with a low attrition rate. In this context, tucatinib, an oral tyrosine kinase inhibitor, has recently been granted approval by regulatory agencies based on evidence from the HER2CLIMB, a clinical trial which randomized patients with metastatic BC to receive trastuzumab and capecitabine with either tucatinib or placebo. A distinctive feature of this study was the inclusion of patients with new or active brain metastases (BMs) at study entry, a population traditionally excluded from clinical trials. Thus, HER2CLIMB provides the first solid evidence of an OS benefit in patients with BC and BMs, addressing a long standing unmet medical need, especially given the high incidence of central nervous system metastatic spread in patients with HER2-positive disease. This review provides an overview of the molecular and clinical landscape of tucatinib for the treatment of advanced BC. It focuses on the technological journey that drove the development of this therapeutic innovation, from preclinical data to clinical practice.

Estrogen deprivation effects of endocrine therapy in breast cancer patients: Incidence, management and outcome

Endocrine therapy is one of the standard adjuvant treatments to reduce the risk of recurrence and mortality in patients with hormone receptor positive early breast cancer. Despite its proven efficacy, ET side effects, which persist over time even if low grade, may deteriorate quality of life. During follow-up visits, emphasis is generally placed on the risk of disease recurrence, while the topic of ET side effects is commonly neglected and discussed only briefly. This could lead to poor adherence to therapy and early treatment discontinuation, resulting in worse survival outcomes. The aim of this review is to provide an overview of the available evidence on the incidence and reporting of ET-related side effects (including vasomotor symptoms, musculoskeletal disorders and genitourinary syndrome of menopause, as well as fatigue, psychological and ocular disorders, dysmetabolic effects and loss of bone density) and of the pharmacological and non-pharmacological strategies available to mitigate symptom burden.

miRNAs in the Box: Potential Diagnostic Role for Extracellular Vesicle-Packaged miRNA-27a and miRNA-128 in Breast Cancer

Circulating extracellular vesicle (EV)-derived microRNAs (miRNAs) are now considered the next generation of cancer "theranostic" tools, with strong clinical relevance. Although their potential in breast cancer diagnosis has been widely reported, further studies are still required to address this challenging issue. The present study examined the expression profiles of EV-packaged miRNAs to identify novel miRNA signatures in breast cancer and verified their diagnostic accuracy. Circulating EVs were isolated from healthy controls and breast cancer patients and characterized following the MISEV 2018 guidelines. RNA-sequencing and real-time PCR showed that miRNA-27a and miRNA-128 were significantly down-regulated in patient-derived EVs compared to controls in screening and validation cohorts. Bioinformatics analyses of miRNA-target genes indicated several enriched biological processes/pathways related to breast cancer. Receiver operating characteristic (ROC) curves highlighted the ability of these EV-miRNAs to distinguish breast cancer patients from non-cancer controls. According to other reports, the levels of EV-miRNA-27a and EV-miRNA-128 are not associated with their circulating ones. Finally, evidence from the studies included in our systematic review underscores how the expression of these miRNAs in biofluids is still underinvestigated. Our findings unraveled the role of serum EV-derived miRNA-27a and miRNA-128 in breast cancer, encouraging further investigation of these two miRNAs within EVs towards improved breast cancer detection.

Risk-Based Therapeutic Strategies for HER2-Positive Early Breast Cancer: A Consensus Paper

Breast cancer represents the most commonly diagnosed neoplasm worldwide and the HER2-positive subtype accounts for nearly 1 in 5 breast cancers. The majority of patients with breast cancer present with an early-stage disease upon diagnosis, which is thus susceptible to virtually curative treatment strategies. For a stage, I T1a/b N0 HER2-positive disease, upfront surgery followed by adjuvant therapy is the preferred approach. However, there is some uncertainty regarding the appropriate management of stage cT1c cN0, as both the neoadjuvant approach and upfront surgery have been proven to be feasible therapeutic options. The aim of this Delphi consensus was to define the best strategies for the treatment of early HER2-positive breast cancer. This work may help clinicians in the management of early HER2-positive breast cancer.

Impaired Seroconversion After Severe Acute Respiratory Syndrome Coronavirus 2 mRNA Vaccine in Patients With Thymic Epithelial Tumors

INTRODUCTION

Thymic epithelial tumors (TETs) are rare malignancies associated with dysregulation of the immune system and humoral- and cell-mediated immunity abnormalities. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine is effective in preventing coronavirus disease 2019 morbidity and mortality. The aim of this study was to evaluate the seroconversion in patients with TET after two doses of mRNA vaccine.

METHODS

This is a prospective study in which consecutive patients with TET were enrolled before receiving the first dose of SARS-CoV-2 mRNA vaccine (BNT162b2 by Pfizer-BioNTech). SARS-CoV-2 spike-binding immunoglobulin (Ig)G antibody serologic levels were analyzed at different time points, including before first vaccine dose (T0), 1 month after the second dose (T2), and 3 months after the second dose (T3).

RESULTS

Overall, 39 patients were included in the analysis. All patients had negative antibody titer results at T0. There were 19 patients (48.7%) in the follow-up with no residual tumor lesion/s (referred as no evidence of disease), and 20 (51.3%) had evidence of disease (ED) and were receiving systemic treatment. Dysregulations of the immune system were diagnosed in 29 patients (74.4%) with Good syndrome (GS) being the most frequent immune disorder (48.7%). At univariate analysis, lack of seroconversion at T2 was significantly associated with ED (p < 0.001) and with GS (p = 0.043). A significant association with impaired seroconversion was confirmed at multivariate analysis for ED (p = 0.00101) but not for GS (p = 0.625).

CONCLUSIONS

Our data revealed that patients with TET with ED had substantially higher probability of impaired seroconversion after SARS-CoV-2 mRNA vaccine as compared with patients with no evidence of disease.

NTRK gene aberrations in triple-negative breast cancer: detection challenges using IHC, FISH, RT-PCR, and NGS

Triple-negative breast cancer (TNBC) is usually an aggressive disease with a poor prognosis and limited treatment options. The neurotrophic tyrosine receptor kinase (NTRK) gene fusions are cancer type-agnostic emerging biomarkers approved by the Food and Drug Administration (FDA), USA, for the selection of patients for targeted therapy. The main aim of our study was to investigate the frequency of NTRK aberrations, i.e. fusions, gene copy number gain, and amplification, in a series of TNBC using different methods. A total of 83 TNBCs were analyzed using pan-TRK immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), real-time polymerase chain reaction (RT-PCR), and RNA-based next-generation sequencing (NGS). Of 83 cases, 16 showed pan-TRK positivity although no cases had NTRK-fusions. Indeed, FISH showed four cases carrying an atypical NTRK1 pattern consisting of one fusion signal and one/more single green signals, but all cases were negative for fusion by NGS and RT-PCR testing. In addition, FISH analysis showed six cases with NTRK1 amplification, one case with NTRK2 copy number gain, and five cases with NTRK3 copy number gain, all negative for pan-TRK IHC. Our data demonstrate that IHC has a high false-positive rate for the detection of fusions and molecular testing is mandatory; there is no need to perform additional molecular tests in cases negativity for NTRK by IHC. In conclusion, the NTRK genes are not involved in fusions in TNBC, but both copy number gain and amplification are frequent events, suggesting a possible predictive role for other NTRK aberrations.

Toxicity profile of antibody-drug conjugates in breast cancer: practical considerations

Antibody-drug conjugates (ADCs) represent a novel and evolving class of antineoplastic agents, constituted by monoclonal antibody linked to biologically active drugs, delivering cytotoxic compounds at the tumor site, reducing the likelihood of systemic exposure and toxicity. They are generally well tolerated, nevertheless some predictable adverse reactions need careful monitoring and timely approach. These include neutropenia, nausea and vomiting, alopecia, diarrhea, left ventricular dysfunction, ILD/pneumonitis. The mechanisms leading to drug-associated toxicities are summarized, and prophylaxis protocols and appropriate management strategies are proposed, based on current literature. This review aims to collect the most updated evidence on toxicities potentially occurring during breast cancer treatment with approved or under clinical investigation (advanced stage) ADCs. A focus is dedicated to monitoring protocols and clinical management, aimed at preventing and/or promptly address relevant problems, in order to avoid premature discontinuation or improper dose reduction.

The effect of the alpha-specific PI3K inhibitor alpelisib combined with anti-HER2 therapy in HER2+/PIK3CA mutant breast cancer

Background

HER2 is amplified or overexpressed in around 20% of breast cancers (BC). HER2-targeted therapies have significantly improved the prognosis of patients with HER2+ BC, however, de novo and acquired resistance to anti-HER2 treatment is common. Activating mutations in the PIK3CA gene are reported in ∼30% of HER2+ BC and are associated with resistance to anti-HER2 therapies and a poor prognosis. Here, we investigated the in vitro and in vivo antitumor efficacy of the alpha-specific PI3K inhibitor alpelisib alone or in combination with anti-HER2 therapy using a panel of HER2+ BC cell lines. We also generated models of acquired resistance to alpelisib to investigate the mechanisms underlying resistance to alpha-specific PI3K inhibition.

Materials and methods

PIK3CA mutant (HCC1954, KPL4 and JMT1) and wild-type (BT474 and SKBR3) HER2+ BC cell lines were used. The HCC1954 and KPL4 cells were chronically exposed to increasing concentrations of alpelisib or to alpelisib + trastuzumab in order to generate derivatives with acquired resistance to alpelisib (AR) and to alpelisib + trastuzumab (ATR). The transcriptomic profiles of HCC1954, KPL4 and their AR and ATR derivatives were determined by RNA sequencing. Cell growth was assessed by MTT assay. Changes in the protein levels of key PI3K pathway components were assessed by Western blotting. Gene expression, cellular and patients' data from the Cancer Dependency Map (DepMap) and KMPlot datasets were interrogated.

Results

HER2+ BC cell lines harboring activating mutations in PIK3CA were less sensitive to single or dual anti-HER2 blockade compared to PIK3CA wild-type cells. Alpelisib treatment resulted in dose-dependent inhibition of the growth of cells with or without PIK3CA mutations and enhanced the antitumor efficacy of anti-HER2 therapies in vitro. In addition, alpelisib greatly delayed tumor growth of HCC1954 xenografts in vivo. Functional annotation of the significantly differentially expressed genes suggested the common activation of biological processes associated with oxidation reduction, cell proliferation, immune response and RNA synthesis in alpelisib-resistant models compared with native cells. Eight commonly upregulated genes (log2 fold-change >1, False Discovery Rate [FDR] <0.05) in models with acquired resistance to alpelisib or alpelisib + trastuzumab were identified. Among these, AKR1C1 was associated with alpelisib-resistance in vitro and with a poor prognosis in patients with HER2+ BC.

Conclusions

Our findings support the use of an alpha-selective PI3K inhibitor to overcome the therapeutic limitations associated with single or dual HER2 blockade in PIK3CA-mutant HER2+ breast cancer. Future studies are warranted to confirm the potential role of candidate genes/pathways in resistance to alpelisib.

Ribociclib in newly diagnosed hepatitis B infection: A case report

Breast cancer is the most frequently diagnosed cancer in women worldwide. Actually CDK4/6 inhibitor Ribociclib is approved for the treatment of metastatic hormone-positive and human epidermal growth factor receptor 2 (HER 2)-negative breast cancer, but comorbidities like infectious or cardiovascular diseases may limit its use.

Case report

A 45-year-old woman was diagnosed with metastatic breast cancer in September 2021; also, her hepatitis screening resulted positive for hepatitis B infection. Patient assumed eradicative therapy for hepatitis and bit after started oncological therapy with Ribociclib.

Outcome

Frequent check of hepatological function was observed since start of eradicative therapy; liver transaminases and bilirubin kept to not rise despite start of oncological treatment with Ribociclib. Patient's Performance Status was also not compromised and revaluation at 4, 9 and 13 months showed partial response and then stable disease.

Discussion

hepatotoxicity of Ribociclib is reported as a possible side effect, and often positivity for hepatitis is cause of exclusion from therapy; in our case, no hepatotoxicity was noted and patient obtained response in terms of control of both infectious and oncological diseases.

Glucocorticoid Receptor and Ovarian Cancer: From Biology to Therapeutic Intervention

Ovarian cancer (OC) is the leading cause of death from gynecological malignancies worldwide. Fortunately, recent advances in OC biology and the discovery of novel therapeutic targets have led to the development of novel therapeutic agents that may improve the outcome of OC patients. The glucocorticoid receptor (GR) is a ligand-dependent transcriptional factor known for its role in body stress reactions, energy homeostasis and immune regulation. Notably, evidence suggests that GR may play a relevant role in tumor progression and may affect treatment response. In cell culture models, administration of low levels of glucocorticoids (GCs) suppresses OC growth and metastasis. Conversely, high GR expression has been associated with poor prognostic features and long-term outcomes in patients with OC. Moreover, both preclinical and clinical data have shown that GR activation impairs the effectiveness of chemotherapy by inducing the apoptotic pathways and cell differentiation. In this narrative review, we summarize data related to the function and role of GR in OC. To this aim, we reorganized the controversial and fragmented data regarding GR activity in OC and herein describe its potential use as a prognostic and predictive biomarker. Moreover, we explored the interplay between GR and BRCA expression and reviewed the latest therapeutic strategies such as non-selective GR antagonists and selective GR modulators to enhance chemotherapy sensitivity, and to finally provide new treatment options in OC patients.

Analysis of circulating extracellular vesicle derived microRNAs in breast cancer patients with obesity: a potential role for Let-7a

BACKGROUND

The incidence of obesity, a known risk factor for several metabolic and chronic diseases, including numerous malignancies, has risen sharply in the world. Various clinical studies demonstrate that excessive Body Mass Index (BMI) may worsen the incidence, prognosis, and mortality rates of breast cancer. Thus, understanding the link tying up obesity and breast cancer onset and progression is critically important, as it can impact patients' survival and quality of life. Recently, circulating extracellular vesicle (EV) derived miRNAs have attracted much attention for their diagnostic, prognostic and therapeutic potential in oncology research. Although the potential role of EV-derived miRNAs in the early detection of breast cancer has been repeatedly mentioned, screening of miRNAs packaged within serum EVs has not yet been reported in patients with obesity.

METHODS

Circulating EVs were isolated from normal weight (NW), and overweight/obese (OW/Ob) breast cancer patients and characterized by Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA), and protein marker expression. Evaluation of EV-associated miRNAs was conducted in a screening (RNA-seq) and a validation (qRT-PCR) cohort. Bioinformatic analysis was performed to uncover significantly enriched biological processes, molecular functions and pathways. ROC and Kaplain-Meier survival analyses were used for clinical significance.

RESULTS

Comparison of serum EV-derived miRNAs from NW and OW/Ob patients detected seven differentially expressed miRNAs (let-7a-5p, miR-122-5p, miR-30d-5p, miR-126-3p, miR-27b-3p, miR-4772-3p, and miR-10a-5p) in the screening cohort. GO analysis revealed the enrichment of protein phosphorylation, intracellular signal transduction, signal transduction, and vesicle-mediated transport among the top biological processes. In addition, the target genes were significantly enriched in pathways related to PI3K/Akt, growth hormones, and insulin signalings, which are all involved in obesity-related diseases and/or breast cancer progression. In the validation cohort, qRT-PCR confirmed a significant down-regulation of EV-derived let-7a in the serum of OW/Ob breast cancer patients compared to NW patients. Let-7a levels also exhibited a negative correlation with BMI values. Importantly, decreased let-7a miRNA expression was associated with higher tumor grade and poor survival in patients with breast cancer.

CONCLUSION

These results suggest that serum-EV derived miRNAs may reflect a differential profile in relation to a patient's BMI, which, once validated in larger cohorts of patients, could provide insights into novel specific biomarkers and innovative targets to prevent the progression of obesity-mediated breast cancer.

Optimizing choices and sequences in the diagnostic-therapeutic landscape of advanced triple-negative breast cancer: An Italian consensus paper and critical review

Triple-negative (TN) metastatic breast cancer (mBC) represents the most challenging scenario withing mBC framework, and it has been only slightly affected by the tremendous advancements in terms of drug availability and survival prolongation we have witnessed in the last years for advanced disease. However, although chemotherapy still represents the mainstay of TN mBC management, in the past years, several novel effective agents have been developed and made available in the clinical practice setting. Within this framework, a panel composed of a scientific board of 17 internationally recognized breast oncologists and 42 oncologists working within local spoke centers, addressed 26 high-priority statements, including grey areas, regarding the management of TN mBC. A structured methodology based on a modified Delphi approach to administer the survey and the Nominal Group Technique to capture perceptions and preferences on the management of TN mBC within the Italian Oncology community were adopted. The Panel produced a set of prioritized considerations/consensus statements reflecting the Panel position on diagnostic and staging approach, first-line and second-line treatments of PD-L1-positive/germline BRCA (gBRCA) wild-type, PD-L1-positive/gBRCA mutated, PD-L1-negative/gBRCA wild-type and PD-L1-negative/gBRCA mutated TN mBC. The Panel critically and comprehensively discussed the most relevant and/or unexpected results and put forward possible interpretations for statements not reaching the consensus threshold.

Abstract P1-11-04: Assessing the clinico-pathological characteristics of HER2 positive metastatic breast cancer patients experiencing radiologic complete response in a nationwide cohort

Background: Up to 6% of patients (pts) with HER2 positive (pos) metastatic breast cancer (MBC) experience a radiologic complete response (rCR) to a first line of therapy, but these results mostly derive from dated and/or limited cohorts. Aim of this study was to define the clinico-pathological characteristics of HER2 positive (pos) MBC pts experiencing a rCR. Methods: Pts were selected from the database of the GIM14 study (NCT02284581) and classified according to the best radiologic response obtained to the first line chemotherapy (CT) and upon time-to-treatment-failure (TTF). rCR was defined as complete response (CR) with a TTF &gt; 3 months. The association across variables was tested through logistic regression and their prognostic impact in terms of overall survival (OS) was estimated using the Kaplan-Meier method and compared using the log-rank test. Results: Of the 3,423 pts included in the GIM14 study, 814 had HER2 pos MBC. After exclusion of pts treated with first line endocrine therapy and/or with TTF &lt; 3 months, 656 pts were included in the present analysis, of which 96 (14.6%) experienced a rCR. Instead, the best response was a partial response for 295 pts (45.0%), stable disease for 221 pts (33.7%), and progression for 44 pts (6.7%). Most pts (59.8%) presented de novo MBC; 379 pts (57.8%) had visceral metastases (mets), 609 pts (92.8%) did not have central nervous system (CNS) involvement and 318 pts (48.5%) had only 1 site of distant mets. Also, 445 pts (67.9%) had hormone receptor (HR) pos disease, a HER2 3+ score at immunohistochemistry (IHC) was present in 59.8% of cases versus 40.2% with HER2 2+ at IHC and in situ hybridization (ISH) + disease. Taxanes were the main CT backbone (489 pts, 74.5%), 341 pts (52.0%) had received a Trastuzumab-Pertuzumab doublet. At multivariable analysis, higher odds of experiencing a rCR were reported for presence of non-visceral mets (OR 1.87, 95%CI 1.10-3.17), low number of metastatic sites (OR 2.42, 95%CI 0.80-7.33 for 1 site only) and HER2 3+ score at IHC (OR 1.80, 95%CI 1.09-2.98). Disease-free interval (DFI) was associated to rCR at univariable but not at multivariable analysis. HR status, CT backbone and type of anti-HER2 regimen were not associated with rCR neither at univariable nor at multivariable analysis. Median follow-up was 76.2 months. Amongst pts with TTF&gt;12 months, those with rCR had a significantly higher OS compared to those not experiencing a rCR (median OS 133 and 90 months, respectively; p=0.0191). OS rates in pts with TTF ≥ 12 months were 97.8% at 2-year follow-up and 59.4% at 5-year follow-up. Instead, in pts with TTF ≥ 60 months, OS rates were 76.7% at 10-year follow-up. Amongst the 96 pts experiencing a CR, 38 had a rCR with TTF between 12 and 60 months, while 22 pts had a rCR with a TTF ≥ 60 months. The remaining pts had a CR with a TTF &lt; 12 months. Pts with HR negative (neg) disease were found to be more likely to experience a rCR with a with TTF between 12 and 60 months, whilst pts with HR pos disease had a higher probability to experience a rCR with a TTF ≥ 60 months (p=0.0074). Pts with HER2 3+ score at IHC had a higher probability to achieve a rCR with a TTF ≥ 12 months compared to pts with HER2 2+ score at IHC and ISH + (p=0.0216). Age at diagnosis, menopausal status, DFI, number and site of mets, CT backbone and anti-HER2 therapy did not influence the duration of the rCR obtained. Conclusions: This study characterized a real-world cohort of HER2 positive MBC patients experiencing radiologic complete response to a first line treatment. Based on these results a clinical trial focused on liquid biopsy-based minimal residual disease is being designed. Novel anti-HER2 agents are gaining momentum as ever increasingly effective treatments and future de-escalation strategies after complete response will represent a growing need.

Citation Format: Linda Cucciniello, Eva Blondeaux, Claudia Bighin, Simona Gasparro, Stefania Russo, Arianna Dri, Palma Pugliese, Andrea Fontana, Giuseppe Naso, Antonella Ferzi, Ferdinando Riccardi, Valentina Sini, Luca Boni, Alessandra Fabi, Filippo Montemurro, Michelino De Laurentiis, Grazia Arpino, Lucia Del Mastro, Lorenzo Gerratana, Fabio Puglisi. Assessing the clinico-pathological characteristics of HER2 positive metastatic breast cancer patients experiencing radiologic complete response in a nationwide cohort [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 P1-11-04.

Serum thymidine kinase activity in patients with HR-positive/HER2-negative advanced breast cancer treated with ribociclib plus letrozole: results from the prospective BioItaLEE trial

BACKGROUND

Thymidine kinase 1 (TK1) is an enzyme downstream of the CDK4/6 pathway, with a critical role in DNA synthesis; serum TK1 activity (sTKa) is a novel liquid biopsy biomarker of tumour cell proliferation.

METHODS

The phase IIIb, BioItaLEE trial (NCT03439046) collected sera from postmenopausal patients with hormone receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) treated with first-line ribociclib plus letrozole at baseline, day 15 of cycle 1 (C1D15), day 1 of cycle 2 (C2D1), and at first imaging. Associations between sTKa assessed at different time points or sTKa dynamic patterns, and progression-free survival (PFS) were evaluated using multivariate Cox models.

RESULTS

Overall, 287 patients were enroled. Median follow-up was 26.9 months. High sTKa (>median) at baseline was associated with higher risk of progression (hazard ratio [HR], 2.21; 95% confidence interval [95% CI], 1.45, 3.37; P = 0.0002); similar results were observed for patients with high sTKa levels at C1D15 and C2D1. Early sTKa dynamic patterns were strongly predictive of PFS. The pattern with high sTKa levels at C2D1 following initial decrease at C1D15 was associated with higher risk of progression versus the pattern with low sTKa levels at both time points (HR, 2.89; 95% CI, 1.57, 5.31; P = 0.0006), while the pattern with high sTKa levels at C1D15 was associated with the shortest PFS (HR, 5.65; CI: 2.84, 11.2; P < 0.0001). Baseline and dynamic sTKa changes provided independent information.

CONCLUSIONS

sTKa appears to be a new promising prognostic and pharmacodynamic biomarker in patients with HR+/HER2- ABC treated with ribociclib plus letrozole as first-line therapy.

The evolving therapeutic landscape of trastuzumab-drug conjugates: Future perspectives beyond HER2-positive breast cancer

A novel class of drugs, antibody-drug conjugates (ADCs), are now rapidly emerging as highly effective treatments for solid tumours. ADCs conjugate conventional chemotherapeutics with highly selective targeted monoclonal antibodies. Anti-HER2 therapies selectively target cancer cells expressing human epidermal growth factor receptor 2 (HER2), among them trastuzumab has been the first HER2-targeting monoclonal antibody to achieve successful results that made it the backbone of anti-HER2 therapies. Trastuzumab drug conjugates (T-DCs), use trastuzumab as a selective antibody to lead cytotoxic drugs inside cancer cells. Trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-Dxd) are the two approved T-DCs. T-Dxd along with other five T-DCs represents "second generation ADCs" that has been firstly tested in HER2 positive breast cancer (BC) and then in HER2-low BC and other cancers showing promising results thanks to extraordinary and innovative pharmacokinetic and pharmacodynamic characteristics. The evidence generated so far are establishing them as a completely new class of agents effective in solid cancer treatments but also warrants physicians against unconventional toxicity profiles. The role of T-DCs in HER2-positive BC has been largely reviewed, while in this review, we provided for the first time in literature an overview of trastuzumab drug conjugates (T-DCs) approved and/or in clinical development with a specific focus on their efficacy and safety profile in HER2-low BC and other solid tumours different from BC. We started by analysing T-DCs biological characteristics that underly the differences in T-DCs pharmacodynamics and safety profile, then presented the main evidence on the activity and efficacy of these emerging T-DCs in HER2-low BC and other HER2 overexpressing and/or mutated solid tumours and lastly, we provided an overview of the complex and still evolving scenario in which these compounds should be allocated. A specific focus on possible combination strategies with other drugs such as immunotherapy, chemotherapy and target therapy, to increase T-DCs activity and eventually overcome future upcoming resistance mechanisms, are here also critically reviewed.

Pertuzumab, Trastuzumab, and an Aromatase Inhibitor for HER2-Positive and Hormone Receptor-Positive Metastatic/Locally Advanced Breast Cancer: PERTAIN Final Analysis

PURPOSE

In PERTAIN's primary analysis (31 months' median follow-up), adding pertuzumab to trastuzumab and an aromatase inhibitor (AI) with/without chemotherapy significantly improved progression-free survival (PFS) in patients with previously untreated HER2-positive and hormone receptor-positive metastatic/locally advanced breast cancer (M/LABC). A potentially enhanced treatment effect was observed in patients with no induction chemotherapy. We present the final analysis (>6 years' median follow-up).

EXPERIMENTAL DESIGN

Patients (N = 258) were randomized 1:1 to pertuzumab (loading/maintenance: 840/420 mg) plus trastuzumab (loading/maintenance: 8/6 mg/kg) q3w and an AI (1 mg anastrozole or 2.5 mg letrozole daily) (Arm A), or trastuzumab and an AI (Arm B). Induction chemotherapy was at investigator discretion.

PRIMARY ENDPOINT

PFS. Key secondary endpoints: overall survival (OS); safety.

RESULTS

Median PFS was 20.6 versus 15.8 months in Arms A and B, respectively (stratified HR, 0.67; P = 0.006). Median OS was 60.2 versus 57.2 months (stratified HR, 1.05; P = 0.78). Pertuzumab treatment effect was potentially enhanced in patients with no induction chemotherapy (26.6 versus 12.5 months). Any-grade adverse events (AEs) occurred in 122 patients per arm (96.1% versus 98.4%); grade ≥3 AEs in 72 (56.7%) and 51 (41.1%); serious AEs in 46 (36.2%) and 28 (22.6%).

CONCLUSIONS

The PFS benefit of pertuzumab was maintained and OS was similar between arms at final analysis. Adding pertuzumab may enhance activity in patients who do not require first-line chemotherapy for M/LABC. No new safety concerns were reported. These data provide additional evidence of the role of first-line pertuzumab and trastuzumab in HER2-positive M/LABC.

Extended Adjuvant Endocrine Treatment in Luminal Breast Cancers in the Era of Genomic Tests

In patients with early-stage endocrine receptor-positive (ER+) breast cancer (BC), adjuvant endocrine therapy (ET) for 5 years is the standard of care. However, for some patients, the risk of recurrence remain high for up to 15 years after diagnosis and extended ET beyond 5 years may be a reasonable option. Nevertheless, this strategy significantly increases the occurrence of side effects. Here we summarize the available evidence from randomized clinical trials on the efficacy and safety profile of extended ET and discuss available clinical and genomic tools helpful to select eligible patients in daily clinical practice.

Extended adjuvant endocrine treatment for premenopausal women: A Delphi approach to guide clinical practice

The use of an aromatase inhibitor (AI) in combination with ovarian function suppression (OFS) has become the mainstay of adjuvant endocrine therapy in high-risk premenopausal patients with hormone receptor-positive breast cancer. Although five years of such therapy effectively reduces recurrence rates, a substantial risk of late recurrence remains in this setting. Multiple trials have shown that extending AI treatment beyond five years could offer further protection. However, as these studies comprised only postmenopausal patients, no direct evidence currently exists to inform about the potential benefits and/or side effects of extended AI + OFS therapies in premenopausal women. Given these grey areas, we conducted a Delphi survey to report on the opinion of experts in breast cancer treatment and summarize a consensus on the discussed topics. A total of 44 items were identified, all centred around two main themes: 1) defining reliable prognostic factors to pinpoint premenopausal patients eligible for endocrine therapy extension; 2) designing how such therapy should optimally be administered in terms of treatment combinations and duration based on patients' menopausal status. Each item was separately discussed and anonymously voted by 12 experts representing oncological institutes spread across Italy. The consensus threshold was reached in 36 out of 44 items (82%). Herein, we discuss the levels of agreement/disagreement achieved by each item in relation to the current body of literature. In the absence of randomized trials to guide the tailoring of extended AI treatment in premenopausal women, conclusions from our study provide a framework to assist routine clinical practice.

Insight on the Role of Leptin: A Bridge from Obesity to Breast Cancer

Leptin is a peptide hormone, mainly known for its role as a mediator of adipose tissue endocrine functions, such as appetite control and energy homeostasis. In addition, leptin signaling is involved in several physiological processes as modulation of innate and adaptive immune responses and regulation of sex hormone levels. When adipose tissue expands, an imbalance of adipokines secretion may occur and increasing leptin levels contribute to promoting a chronic inflammatory state, which is largely acknowledged as a hallmark of cancer. Indeed, upon binding its receptor (LEPR), leptin activates several oncogenic pathways, such as JAK/STAT, MAPK, and PI3K/AKT, and seems to affect cancer immune response by inducing a proinflammatory immune polarization and eventually enhancing T-cell exhaustion. In particular, obesity-associated hyperleptinemia has been related to breast cancer risk development, although the underlying mechanism is yet to be completely clarified and needs to be deemed in light of multiple variables, such as menopausal state and immune response. The aim of this review is to provide an overview of the potential role of leptin as a bridge between obesity and breast cancer and to establish the physio-pathological basis of the linkage between these major health concerns in order to identify appropriate and novel therapeutic strategies to adopt in daily clinical practice.

Controversial topics in metastatic HR+/HER2- breast cancer: Guiding treatment by a modified Delphi approach

The treatment of HR+/HER2- metastatic breast cancer with cyclin-dependent kinases 4 and 6 inhibitors combined with endocrine therapy has recently emerged as the most relevant therapeutic strategy. However, in routine clinical practice, the best therapeutic approach in patients with comorbidities at early relapsing or ab initio metastatic disease, PI3KCA mutation, is still debated among oncologists. Given these areas of uncertainty, we conducted a Delphi survey to describe and confront the level of agreement or disagreement between clinicians working in referral vs local spoke oncological hospitals and summarize a consensus on these debated topics. In total, 56 items were drafted using the Nominal Group Technique and used for the Delphi Survey. A total of 46 clinicians participated in the survey. Overall, the consensus threshold among all participants was reached in 46/56 items (82%), and Delphi Survey results showed a high level of consensus. For the 10 items (18%) that did not reach the consensus threshold, possible explanations considering differences in clinical practice and recent findings from literature are provided in the Discussion. Outcomes from the present survey may help guide treatment in multiple comorbidities, early recurring and ab initio metastatic disease, and PI3KCA mutation, where evidence from randomized trials and level 1 evidence is currently missing.

Safety and immunogenicity of the COVID-19 vaccine BNT162b2 for patients with breast and gynecological cancer on active anticancer therapy: Results of a prospective observational study

Background

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are highly effective. Nevertheless, immunocompromised participants were excluded from randomized controlled clinical trials. This study evaluates the efficacy and safety of the Pfizer/BioNTech BNT162b2 (BNT162b2) vaccine in patients with breast and gynecological cancer treated with active anticancer therapy versus a control cohort of healthy participants.

Methods

Immune responses to the BNT162b2 vaccine in patients with breast cancer (n = 44) or a gynecological malignancy (n = 6) on active anticancer therapy (28 on chemotherapy, mostly anthracycline- or taxane-based, and 22 on target therapy) and in a control cohort of participants without cancer (n = 67) were investigated by SARS-CoV-2 neutralizing antibody titers measured by S1-binding immunoglobulin G (IgG) concentrations assessed using the LIAISON XL tools (DiaSorin S.p.A.). Response was assessed after a second dose of the BNT162b2 vaccine administered before and at least 3 weeks after the vaccine dose.

Results

Overall, 43/50 (86%) patients of the cancer cohort (74% in the breast cancer group and 100% in the gynecological malignancy group) developed IgG antibodies after the second dose of the BNT162b2 vaccine. There were no statistically significant differences in responder rates between patients treated with chemotherapy and those on target therapy. The majority of patients who received chemotherapy with or without target therapy, 21/28 (75%), developed a reliable antibody titer after a vaccine. All seven non-responder patients were undergoing an anthracycline-based regimen. Based on IgG levels (0–400 AU/ml), patients were classified as negative (‘non-responders’), weakly positive, or strongly positive (‘responders’). No delay in cancer therapy schedule or reported side effects were recorded after BNT162b2 vaccine administration. All healthy participants were strongly positive. Responder rates differed significantly between the two study cohorts (p < 0.001).

Conclusions

Most patients develop antibody titers after the second immunization. However, given the persistence of non-responders or weak responders, additional immunization booster seems to be required, along with proactive planning in the vaccination schedule, with vaccine administration spaced out over time with respect to chemotherapy.

Circulating tumor DNA (ctDNA) and serum thymidine kinase 1 activity (TKa) matched dynamics in patients (pts) with hormone receptor–positive (HR+), human epidermal growth factor 2–negative (HER2-) advanced breast cancer (ABC) treated in first-line (1L) with ribociclib (RIB) and letrozole (LET) in the BioItaLEE trial

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Background: Independent early dynamic assessment (baseline [D0] and day 15 of first cycle [D15]) of both TKa and ctDNA was prognostic and predictive in pts with HR+, HER2− ABC treated with RIB+LET enrolled in the BioItaLEE trial (NCT03439046). Here we performed a combined analysis of these two biomarkers. Methods: 287 pts were enrolled in the study. Overall, early dynamics were assessable for both biomarkers in 241/287 pts (84.0%). Methods applied for ctDNA and TKa evaluation were previously reported. For ctDNA, samples were defined as wild type (WT) if no mutations were observed at D0 and D15, ctDNA positive (+) if with or negative (-) if without a primary target mutation at D15. Samples were TKa+ or TKa- if TKa levels were above or below the limit of detection at D15. According to ctDNA and TKa pts were classified as: WT/TKa-, WT/TKa+, ctDNA-/TKa-, ctDNA-/TKa+, ctDNA+/TKa- and ctDNA+/TKa+ and then divided into 3 main study groups (GRs) WT/TKa- (GR1, n = 126), WT/TKa+, ctDNA-/TKa-, ctDNA-/TKa+, ctDNA+/TKa- (GR2, n = 96) and ctDNA+/TKa+ (GR3, n = 19). The association between biomarkers and PFS (progression-free survival) was estimated using Kaplan-Meier analysis and multivariate Cox models with 95% confidence intervals (CIs) adjusted for clinical variables. Results: Median follow-up was 26.9 months. In multivariate Cox models both TKa dynamics and mutational tumor burden at D15 were independently predictive of PFS. Hazard ratios (HRs) were 0.37 (95% CI: 0.23-0.60; p < 0.0001) for WT vs ctDNA+ and 0.56 (95% CI: 0.32-1.00; p = 0.0506) for ctDNA- vs ctDNA+. For TKa, HR was 0.49 (95% CI: 0.30-0.80; p = 0.0040) in TKa- vs TKa+. Interestingly combining the two variables further improve prediction of outcome. HRs for TKa- vs TKa+ were 0.17 (95% CI: 0.09-0.32; p < 0.0001), 0.28 (95% CI: 0.13-0.59; p = 0.0009) and 0.44 (95% CI: 0.23-0.86; p = 0.0169) in WT, ctDNA- and ctDNA+ pts, respectively. Considering the 3 study GRs, median PFSs (95% CI) were not reached (27.89, NE), 19.58 (13.83, 23.39) and 6.65 (2.83, 12.16) months in GR1, GR2 and GR3, respectively, p < 0.001. At multivariate Cox models, HRs of GR1 and GR2 compared with GR3 were 0.17 (95% CI: 0.09-0.32; p < 0.0001) and 0.37 (95% CI: 0.20-0.67; p = 0.001) respectively. Conclusions: These findings suggest that combining the early dynamic assessment of both ctDNA and TKa may improve outcome prediction in pts treated with RIB+LET. Pts with ctDNA+/TKa+ are strongly enriched for non-responders. TKa and ctDNA capture different features of tumor biological activity and their combination warrants further evaluation in relation to other treatments, settings, and diseases. Clinical trial information: NCT03439046.

Impaired seroconversion after SARS-COV-2 mRNA vaccine in patients with thymic epithelial tumors

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Background: Thymic epithelial tumors (TET) are rare malignancies associated with dysregulation of the immune system and humoral and cell mediated immunity abnormalities. Anti-syndrome coronavirus type 2 (SARS-CoV-2) vaccine is effective at preventing COVID-19 morbidity and mortality. No published data are available regarding the immunization in TET patients (pts). The aim of this study was to evaluate the immunization in TET pts who received two doses of mRNA vaccine, by longitudinal serological detection of SARS-COV-2 spike-binding IgG antibody. Methods: Starting from April 2021 to October 2021, consecutive TET pts referred to the Rare Tumors Coordinating Center of Campania Region (CRCTR - Naples, Italy) were enrolled. All study subjects received two doses of COVID-19 mRNA vaccine (BNT162b2 by Pfizer-BioNTech). SARS-CoV-2 spike-binding IgG antibody (Ab) serological levels were analyzed by centralized chemiluminescent immunoassay (CLIA) at different time-points, including before 1st vaccine dose (T0) and 1 month after 2nd dose (T2). Cut-off for Ab titers positivity was > 25 AU/mL. Results: Forty pts were enrolled; 23 (57.5%) were female and 17 (42.5%) male. Eleven pts (27.5%) suffered from thymic carcinoma, 28 (70%) thymoma, and 1 (2.5%) thymic hyperplasia. At the time of study enrollment, 20 pts (50%) had no evidence of disease (NED) and were in follow-up; the remaining 20 pts had evidence of disease (ED) by imaging and were receiving systemic treatment (55% oral low-dose etoposide-based therapy, 40% somatostatin analogs + prednisone, 5% supportive care). Immune system disorders were diagnosed in 29 TET pts (72.5%): 19 pts (47.5%) had Good’s Syndrome (GS) and 10 (25%) other immune disorders. At T0, all enrolled pts had negative Ab titers and no prior SARS-CoV-2 infection. At T2, Ab data were available for 37 pts (92.5%): 18 pts (48.7%) had positive Ab titers, whereas 19 (51.3%) did not achieve seroconversion. Among pts with ED, seroconversion was achieved only in 2 cases (11.8%). Lack of seroconversion at T2 was significantly associated with ED (Fisher's exact test p: 0.0001) and with the presence of GS (Fisher's exact test p: 0.0489). No significant association of seroconversion with other immune disorders and disease features was found. Conclusions: Our data showed that TET pts with ED had substantially higher probability of impaired seroconversion after SARS-COV-2 vaccine as compared with NED pts. We warrant further studies to evaluate the role of disease status, anti-tumor treatments and immune disorders in post-vaccine immunization of TET pts.

Prevalence of Sarcopenia in Women with Breast Cancer

Sarcopenia is a common finding in patients with cancer and potentially influences the patient’s outcome. The aim of this study was to evaluate the prevalence of sarcopenia, according to the European Working Group on Sarcopenia in Older People, in a sample of women with breast cancer (BC) and a BMI lower than 30 kg/m2. This cross-sectional study was conducted in patients with BC, stage 0-III, and receiving therapy for BC; the women were recruited at the Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy. A control group with similar age and BMI was selected from the internal database. Anthropometry, bioimpedance analysis (BIA) and hand grip strength (HGS) were measured to detect sarcopenia. A total of 122 patients (mean age 49.3 ± 11.0 years, BMI 24.6 ± 3.0 kg/m2) and 80 healthy controls were analyzed. Sarcopenia was found in 13.9% patients with BC, while none of the subjects in the control group was sarcopenic. By comparing BC patients with and without sarcopenia and the control group, the fat-free mass of sarcopenic BC patients were significantly lower than those of both non-sarcopenic BC patients and the control (p < 0.05). The phase angle was also significantly lower in sarcopenic patients (−0.5 degrees, p = 0.048) than in the control group. Considering the prevalence of sarcopenia in patients with BC, our findings suggest the usefulness of body composition and HGS evaluation for early screening of sarcopenia to reduce the risk of associated complications.

Prognostic Relevance of Progesterone Receptor Levels in Early Luminal-Like HER2 Negative Breast Cancer Subtypes: A Retrospective Analysis

Introduction

In luminal-like early breast cancer (BC), the lack of Progesterone Receptor (PR) expression generally correlates with more aggressive behavior but the clinical validity of low PR levels remains a debated issue.

Methods

The main aim of this retrospective analysis was to assess the survival outcome (Breast cancer specific survival, BCSS) in a cohort of 687 luminal-like HER2 negative early BC patients treated at our Institutions from January 2000 to December 2018, using a sub-classification of tumors in subgroup 1 (PR high/Ki67 low), subgroup 2 (PR high/Ki67 high), subgroup 3 (PR low/Ki67 low), subgroup 4 (PR low/Ki67 high) according to PR and Ki67 values.

Results

At a median follow-up of 7 years, BCSS rates were 96.3%, 89%, 86.8% and 85% in the subgroup 1, 2, 3, 4 respectively. Overall, a statistically significant difference in BCSS rates was observed among the 4 subgroups (p=0.0036). On univariate analysis, post-menopause, older age (≥ 50 years), low PR and high Ki67 expression, poorly differentiated grade and size ≥ 2 cm as well as luminal B-like tumors (subgroups 2, 3, 4) were significantly associated with a worse BCSS. Multivariate analysis identified grade, size and subgroup classification of BC as independent prognostic markers of poorer outcome. In particular, subgroups 4, 3 and 2 displayed a significantly higher risk of BC-related death (HR=4.11; p=0.008; HR=3.43; p=0-007; HR=2.57; p=0.020, respectively) when compared to subgroup 1.

Conclusions

Our results support the usefulness of PR and Ki67 levels as prognostic markers, corroborating their crucial role in the decision-making process of patients with luminal-like HER2 negative early BC. Clinical application of these parameters should be assessed prospectively.

Impact of a cardio-oncology unit on prevention of cardiovascular events in cancer patients

Aims

As the world population grows older, the co‐existence of cancer and cardiovascular comorbidities becomes more common, complicating management of these patients. Here, we describe the impact of a large Cardio‐Oncology unit in Southern Italy, characterizing different types of patients and discussing challenges in therapeutic management of cardiovascular complications.

Methods and results

We enrolled 231 consecutive patients referred to our Cardio‐Oncology unit from January 2015 to February 2020. Three different types were identified, according to their chemotherapeutic statuses at first visit. Type 1 included patients naïve for oncological treatments, Type 2 patients already being treated with oncological treatments, and Type 3 patients who had already completed cancer treatments. Type 2 patients presented the highest incidence of cardiovascular events (46.2% vs. 12.3% in Type 1 and 17.9% in Type 3) and withdrawals from oncological treatments (5.1% vs. none in Type 1) during the observation period. Type 2 patients presented significantly worse 48 month‐survival (32.1% vs. 16.7% in Type 1 and 17.9% in Type 3), and this was more evident when in the three groups we focused on patients with uncontrolled cardiovascular risk factors or overt cardiovascular disease at the first cardiologic assessment. Nevertheless, these patients showed the greatest benefit from our cardiovascular assessments, as witnessed by a small, but significant improvement in ejection fraction during follow‐up (Type 2b: from 50 [20; 67] to 55 [35; 65]; P = 0.04).

Conclusions

Patients who start oncological protocols without an accurate baseline cardiovascular evaluation are at major risk of developing cardiac complications due to antineoplastic treatments.

Emetogenicity of Antibody-Drug Conjugates (ADCs) in Solid Tumors with a Focus on Trastuzumab Deruxtecan: Insights from an Italian Expert Panel

Simple Summary

Four antibody-drug conjugates (ADCs) are approved for the treatment of solid tumors, improving the therapeutic index. Despite their high selectivity, nausea and vomiting are the most frequently observed side effects. A deeper understanding of the potential risk for nausea and vomiting is crucial, as they can affect patients’ quality of life and treatment adherence. Prophylaxis with the potential combination of antiemetic therapy with complementary non-pharmacological approaches are even more important, considering that ADC therapies are generally given continuously until disease progression or the occurrence of toxicities.

Abstract

In the past decade, nine antibody-drug conjugates (ADCs) have been approved for the treatment of various tumors, four of which specifically for solid malignancies. ADCs deliver the cytotoxic payload to the cancer site, thereby improving chemotherapy efficacy while reducing systemic drug exposure and toxicity. With their high selectivity, ADCs are associated with a manageable side-effect profile, with nausea and vomiting being among the most frequent toxicities, although this may vary according to the respective ADC and the associated payload. Information about the emetic risk of the new ADC compounds is limited. Three virtual focus groups of Italian oncologists were held to raise awareness on the importance of an antiemetic prophylaxis regimen to prevent and mitigate ADC-associated emesis and its sequelae. After reviewing published evidence and guidelines, the three expert panels shared their experience on the early use of ADCs gained through the participation in specific clinical trials and their clinical practice. The following issues were discussed: antiemetic therapy during trastuzumab deruxtecan treatment, with a protocol adopted at the San Raffaele Hospital (Milan, Italy); the use of steroids; the management of anticipatory nausea during trastuzumab deruxtecan therapy; nutritional counselling; and effective doctor–patient communication. The experts acknowledged that recommendations should be drug-specific, and formulated opinion-based advice intended to guide physicians in their daily practice until further evidence emerges.

Abstract GS3-07: Circulating tumor DNA (ctDNA) dynamics in patients with hormone receptor positive (HR+)/HER2 negative (HER2-) advanced breast cancer (aBC) treated in first line with ribociclib (R) and letrozole (L) in the BioItaLEE trial

Background: ctDNA analysis is emerging as an attractive non-invasive approach to characterize tumor biology, describe its evolution over time, and predict treatment benefit. Here, we assessed the prognostic and predictive role of baseline and dynamic ctDNA analysis in HR+/HER2- aBC patients (pts) treated with R+L. Methods: 287 postmenopausal pts were enrolled in the BioItaLEE trial (NCT03439046). Liquid biopsies were collected at baseline (D0; n=263), day 15 of cycle 1 (D15; n=238), day 1 of cycle 2 (C2D1; n=241) and at first imaging (FI, at approximately 12 weeks; n=206). ctDNA analysis was carried out using a 533-amplicon Custom AmpliSeq HD Panel, with amplicons covering the coding exons of 39 BC-related genes (limit of detection: 0.1%). Target mutations were defined as single-nucleotide variant (SNV) or Insertion/Deletion detected at D0. When multiple target mutations were detected, the one with the highest variant allele frequency (VAF) was considered. The association between pre-treatment and on-treatment ctDNA dynamics with progression-free survival (PFS) was assessed using Multivariate Cox models. VAF clearance was defined as 100% decrease in a target mutation. Results: Median follow-up was 26.9 months and median PFS was 23.39 (20.8-NE) months. At baseline, target mutations were detected in 113 pts (43.0%), whereas 150 pts were wild-type (wt). Mean (SD) pre-treatment VAF at D0 was 11.3% (14.4). The absence of a target mutation at D0 was associated with good prognosis (HR: 0.41, 95% CI: 0.27–0.61; p&lt;0.0001). Considering early ctDNA dynamics, a significant VAF reduction was observed at D15 and C2D1 with a mean (SD) change of -64.3% (55.9) and -68.6% (52.2), respectively. In pts with a target mutation detected at baseline, early VAF clearance was observed in 47.1% of pts at D15 and in 52.4% of pts at C2D1. Clearance at D15 or C2D1 was associated with improved PFS (D15, HR: 0.51, 95% CI: 0.28-0.91, p=0.0228; C2D1, HR: 0.44, 95% CI: 0.25-0.78, p=0.0052). Pts achieving clearance at D15, which was maintained at C2D1 (39.4%) had the lowest risk of progression compared to those who had no clearance at any or both timepoints (HR: 0.40, 95% CI: 0.20-0.79; p=0.084). Monitoring of the 150 pts without a detectable target mutation at baseline revealed a new, detectable mutation at later timepoints (D15, C2D1 and FI) in 34 pts (22.7%). The absence of new mutations was associated with a lower risk of progression (HR: 0.45, 95% CI: 0.24-0.85; p=0.0143). Considering all time points individually, D15 was the most informative of patient outcome. Indeed, pts without mutation at D15 (42.9%) had an extremely favorable outcome, either because they achieved early treatment-related clearance or maintained baseline absence of a target mutation (HR: 0.32, 95% CI: 0.20-0.51; p&lt;0.0001). Notably, in pts with detectable target mutation at D15, a VAF below the median showed a trend for better prognosis versus high VAF (HR: 0.56, 95% CI: 0.30-1.04; p=0.065). Conclusions: The presence of a detectable mutation in baseline liquid biopsies appears to be a negative prognostic factor. Within this high-risk group, early VAF clearance during the first R+L cycle was informative of treatment benefit and associated with a lower risk of progression. Monitoring of ctDNA in patients without baseline mutations demonstrated that the detection of new mutations by FI assessment was associated with worse outcome. Overall, pre-treatment and early dynamics of ctDNA (assessed by NGS) represent promising prognostic and predictive biomarkers in patients with HR+/HER2- aBC treated with ribociclib/letrozole in the first-line. Further studies are warranted to validate the clinical utility of these biomarkers.

Citation Format: Giampaolo Bianchini, Luca Malorni, Grazia Arpino, Alberto Zambelli, Fabio Puglisi, Lucia Del Mastro, Marco Colleoni, Filippo Montemurro, Giulia Bianchi, Ida Paris, Giacomo Allegrini, Marina Elena Cazzaniga, Michele Orditura, Claudio Zamagni, Stefano Tamberi, Daniela Castelletti, Matteo Benelli, Maurizio Callari, Angela Santoro, Michelino De Laurentiis. Circulating tumor DNA (ctDNA) dynamics in patients with hormone receptor positive (HR+)/HER2 negative (HER2-) advanced breast cancer (aBC) treated in first line with ribociclib (R) and letrozole (L) in the BioItaLEE trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS3-07.

Post-Progression Treatments after Palbociclib plus Endocrine Therapy in HR+/HER2- Metastatic Breast Cancer Patients: What Is the Better Choice?

BACKGROUND

To date, a consensus has not yet been reached about the therapy sequence after disease progression (PD) on CDK4/6 inhibitors in patients with HR+/HER2- metastatic breast cancer (MBC).

OBJECTIVES

The present study assesses, in a real-world setting, the activity of different subsequent therapies in patients who experienced a PD on palbociclib (P) + endocrine therapy (ET), to evaluate the best therapy sequence.

METHODS

This is a multicenter retrospective observational study. Records of consecutive HR+/HER2- MBC patients from January 2017 to May 2019 were reviewed. The primary endpoint was the evaluation of progression-free survival (PFS) according to subsequent treatment lines after progression on P+ET. Toxicity data were also collected.

RESULTS

The outcomes were analyzed in 89 MBC patients that had progressed on previous P+ET: 17 patients were on hormone therapy (HT) and 31 patients on chemotherapy (CT) as second-line treatments; seven patients were on HT and 34 on CT as third-line therapies. PFS of patients treated with HT as second-line therapy is significantly improved when compared with patients treated with CT (p=0.01). Considering third-line settings, the difference in PFS was not statistically different between HT and CT. A better outcome in terms of toxicity is observed among HT patients for both second- and third-line therapies.

CONCLUSIONS

patients who were progressive on P+ET could still benefit from a subsequent ET. In patients who experienced a good efficacy from prior ET, without visceral metastatic sites, HT seems the most suitable option, when compared to CT, also in terms of safety.

Long-Term Outcomes with Pharmacological Ovarian Suppression during Chemotherapy in Premenopausal Early Breast Cancer Patients

BACKGROUND

Although use of gonadotropin-releasing hormone agonist (GnRHa) during chemotherapy is an established strategy to protect ovarian function in premenopausal breast cancer patients, no long-term safety data are available raising some concerns in women with hormone receptor-positive disease. There are controversial data on its fertility preservation potential.

METHODS

The PROMISE-GIM6 is a multicenter, randomized, open-label, phase III superiority trial conducted at 16 Italian centers from October 2003 to January 2008. Eligible patients were randomized to (neo)adjuvant chemotherapy alone (control arm) or combined with the GnRHa triptorelin (GnRHa arm). Primary planned endpoint was incidence of chemotherapy-induced premature ovarian insufficiency (POI). Post-hoc endpoints were disease-free survival (DFS), overall survival (OS), and post-treatment pregnancies. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Of 281 randomized patients, 80.4% had hormone receptor-positive breast cancer. Median follow-up was 12.4 years (interquartile range = 11.3-13.2 years). No differences in 12-year DFS (65.7% [95% CI = 57.0% to 73.1%] in GnRHa arm vs. 69.2% [95% CI = 60.3% to 76.5%] in control arm; HR = 1.16, 95% CI = 0.76 to 1.77) nor in 12-year OS (81.2% [95% CI = 73.6% to 86.8%] in GnRHa arm vs. 81.3% [95% CI = 73.1% to 87.2%] in control arm; HR = 1.17, 95% CI = 0.67 to 2.03) were observed. In patients with hormone receptor-positive disease, the HR was 1.02 (95% CI = 0.63 to 1.63) for DFS and 1.12 (95% CI = 0.59 to 2.11) for OS. In the GnRHa and control arms, 9 and 4 patients had a post-treatment pregnancy, respectively (HR = 2.14, 95% CI = 0.66 to 6.92).

CONCLUSIONS

Final analysis of the PROMISE-GIM6 trial provides reassuring results on the safety of GnRHa use during chemotherapy as a strategy to preserve ovarian function in premenopausal patients with early breast cancer, including those with hormone receptor-positive disease.

Final analysis of the PROMISE-GIM6 phase III trial assessing GnRH agonist use during chemotherapy as a strategy to preserve ovarian function in premenopausal patients with early breast cancer

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Background: Current guidelines recommend GnRH agonist (GnRHa) use during chemotherapy (CT) as a strategy to reduce the risk of premature ovarian insufficiency (POI) in premenopausal patients with early breast cancer (EBC). However, no long-term safety data are available raising some concerns on concurrent use of GnRHa during CT in patients with hormone receptor-positive disease. In addition, there is no evidence on the protective role of this strategy in patients with germline BRCA mutations ( mBRCA). Here, we report the final analysis of the PROMISE-GIM6 phase III randomized study, the largest trial addressing the role of GnRHa use during CT in premenopausal EBC patients (Del Mastro et al, JAMA 2011 & Lambertini et al, JAMA 2015). Methods: From October 2003 to January 2008, 281 premenopausal patients aged 18 to 45 years with stage I-III EBC candidates for (neo)adjuvant CT were randomized to receive CT alone or combined with the GnRHa triptorelin. Primary endpoint was incidence of CT-induced POI (defined as amenorrhea and post-menopausal FSH/estradiol levels 1 year following CT). This final analysis reports on post-treatment pregnancies, disease-free survival (DFS) and overall survival (OS). An exploratory descriptive analysis in mBRCA patients is also reported. (ClinicalTrial.gov: NCT00311636) Results: Of the 281 randomized patients (CT+GnRHa arm = 148; CT alone arm = 133), 80% had hormone receptor-positive disease. At the time of this final analysis, 38 (13.5%) patients were lost to follow-up. Median follow-up was 12.4 years (IQR: 11.3-13.2 years). In the CT+GnRHa and CT alone arms, respectively, 9 (10-year cumulative incidence of pregnancy 6.5%, 95% CI 3.5%-12.3%) and 4 (10-year cumulative incidence of pregnancy 3.2%, 95% CI 1.2%-8.3%) patients had a post-treatment pregnancy (HR 2.14, 95% CI 0.66-6.92). No differences in 10-year DFS (72.4% in CT+GnRHa arm vs. 71.2% in CT alone arm: HR 1.16, 95% CI 0.76-1.77) nor in 10-year OS (82.0% in CT+GnRHa arm vs. 85.9% in CT alone arm: HR 1.17, 95% CI 0.67-2.03) were observed. There was no interaction between treatment effect and hormone receptor status. In patients with hormone receptor-positive disease, HR was 1.02 (95% CI 0.63-1.63) for DFS and 1.12 (95% CI 0.59-2.11) for OS. Out of 43 patients tested for BRCA, overall incidence of POI, irrespective of treatment arm, was 20% in mBRCA patients (n = 10) and 12% in patients without mBRCA (n = 33). In mBRCA patients, incidence of POI was 0% and 33% in the CT+GnRHa and CT alone arms, respectively. One post-treatment pregnancy was described in a patient with mBRCA1 in the CT alone arm. Conclusions: The final analysis of the PROMISE-GIM6 trial at a median follow-up of 12.4 years provides reassuring evidence on the safety of GnRHa use during CT as a strategy to preserve ovarian function in premenopausal patients with hormone receptor-positive EBC. Clinical trial information: NCT00311636.

Overall Survival of CDK4/6-Inhibitor-Based Treatments in Clinically Relevant Subgroups of Metastatic Breast Cancer: Systematic Review and Meta-Analysis

BACKGROUND

Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors + endocrine therapy (ET) prolonged progression-free survival as first- or second-line therapy for hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer prognosis. Given the recent publication of overall survival (OS) data for the 3 CDK4/6-inhibitors, we performed a meta-analysis to identify a more precise and reliable benefit from such treatments in specific clinical subgroups.

METHODS

We conducted a systematic literature search to select all available phase II or III randomized clinical trials of CDK4/6-inhibitors + ET reporting OS data in first- or second-line therapy of HR+/HER2-negative pre- or postmenopausal metastatic breast cancer. A random effect model was applied for the analyses. Heterogeneity was assessed with I2statistic. Subgroup analysis was performed to explore the effect of study-level factors. The project was registered in the Open Science Framework database (doi: 10.17605/OSF.IO/TNZQP).

RESULTS

Six studies were included in our analyses (3421 patients). A clear OS benefit was observed in patients without (hazard ratio [HR] = 0.68, 95% confidence interval [CI] = 0.54 to 0.85, I2 = 0.0%) and with visceral involvement (HR = 0.76, 95% CI = 0.65 to 0.89, I2 = 0.0%), with at least 3 metastatic sites (HR = 0.75, 95% CI = 0.60 to 0.94, I2 = 11.6%), in an endocrine-resistant (HR = 0.79, 95% CI = 0.67 to 0.93, I2 = 0.0%) and sensitive subset (HR = 0.73, 95% CI = 0.61 to 0.88, I2 = 0.0%), for younger than 65 years (HR = 0.80, 95% CI = 0.67 to 0.95, I2 = 0.0%) and 65 years or older (HR = 0.71, 95% CI = 0.53 to 0.95, I2 = 44.4%), in postmenopausal (HR = 0.76, 95% CI = 0.67 to 0.86, I2 = 0.0%) and pre- or perimenopausal setting (HR = 0.76, 95% CI = 0.60 to 0.96, I2 = 0.0%) as well as in chemotherapy-naïve patients (HR = 0.72, 95% CI = 0.55 to 0.93, I2 = 0.0%).

CONCLUSIONS

CDK4/6-inhibitors + ET combinations compared with ET alone improve OS independent of age, menopausal status, endocrine sensitiveness, and visceral involvement and should be preferred as upfront therapy instead of endocrine monotherapy.

T-DM1 versus pertuzumab, trastuzumab and a taxane as first-line therapy of early-relapsed HER2-positive metastatic breast cancer: an Italian multicenter observational study

Background

The current standard first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive (+) metastatic breast cancer is the combination of pertuzumab, trastuzumab and a taxane (P + T + taxane), while standard second-line is ado-trastuzumab-emtansine (T-DM1). The registration trial of pertuzumab, however, did not include early-relapsing patients, defined as patients experiencing tumor relapse ≤12 months from the end of (neo)adjuvant anti-HER2 therapy. Conversely, the pivotal trial of T-DM1 included some patients relapsing ≤6 months after the end of (neo)adjuvant trastuzumab. Thus, a proportion of early-relapsing patients are currently eligible to receive T-DM1 as first-line treatment. Nevertheless, no direct comparison exists between the two regimens in this clinical setting.

Patients and methods

We retrospectively compared T-DM1 versus P + T + taxane as first-line treatment in two cohorts of early-relapsing patients in an Italian ‘real-world’ setting, involving 14 public health care institutions. The primary endpoint was progression-free survival. Secondary endpoints included patients' characterization, overall survival and post-progression survival. Univariate and multivariate analyses were carried out. All tests were two-sided and a P ≤ 0.05 was considered statistically significant.

Results

Among 1252 screened patients, 75 met the inclusion criteria. Forty-four (58.7%) received P + T + taxane and 31 (41.3%) received T-DM1. The two cohorts showed similar characteristics of aggressiveness and no significant differences in treatment history. T-DM1, compared with P + T + taxane was associated with worse progression-free survival (adjusted hazard ratio: 2.26, 95% confidence interval: 1.13-4.52, P = 0.021) and overall survival (adjusted hazard ratio: 3.95, 95% confidence interval: 1.38-11.32, P = 0.010), irrespective of previous (neo)adjuvant treatment, age, hormone receptors status, time-to-relapse (≤6 months or within 6-12 months) and presence of visceral/brain metastases. No differences were observed in post-progression survival (P = 0.095).

Conclusions

Our study suggests superiority for P + T + taxane over T-DM1 as up-front treatment of early-relapsing HER2+ metastatic breast cancer, which merits further assessment in larger and prospective trials.

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This is the first study comparing pertuzumab + trastuzumab + taxane (P + T + taxane) with T-DM1 in early-relapsing HER2+ MBC.

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The majority of early-relapsing HER2+ MBC have high-grade, node-positive, large primary tumors.

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First-line T-DM1 compared with P + T + taxane is associated with worse progression-free survival.

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First-line T-DM1 compared with P + T + taxane is associated with worse overall survival.

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Post-progression survival does not differ between the two treatments cohorts.

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.

Endocrine-Based Treatments in Clinically-Relevant Subgroups of Hormone Receptor-Positive/HER2-Negative Metastatic Breast Cancer: Systematic Review and Meta-Analysis

A precise assessment of the efficacy of first-/second-line endocrine therapies (ET) ± target therapies (TT) in clinically-relevant subgroups of hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer (MBC) has not yet been conducted. To improve our current knowledge and support clinical decision-making, we thus conducted a systematic literature search to identify all first-/second-line phase II/III randomized clinical trials (RCT) of currently approved or most promising ET ± TT. Then, we performed a meta-analysis to assess progression-free (PFS) and/or overall survival (OS) benefit in several clinically-relevant prespecified subgroups. Thirty-five RCT were included (17,595 patients). Pooled results show significant reductions in the risk of relapse or death of 26-41% and 12-27%, respectively, depending on the clinical subgroup. Combination strategies proved to be more effective than single-agent ET (PFS hazard ratio (HR) range for combinations: 0.60-0.65 vs. HR range for single agent ET: 0.59-1.37; OS HR range for combinations: 0.74-0.87 vs. HR range for single agent ET: 0.68-0.98), with CDK4/6-inhibitors(i) + ET being the most effective regimen. Single agent ET showed comparable efficacy with ET+TT combinations in non-visceral (p = 0.63) and endocrine sensitive disease (p = 0.79), while mTORi-based combinations proved to be a valid therapeutic option in endocrine-resistant tumors, as well as PI3Ki + ET in PIK3CA-mutant tumors. These results strengthen international treatment guidelines and can aid therapeutic decision-making.