Concordance of PD-L1 Expression in Metastatic Triple-negative Breast Cancer Between the 22C3 and E1L3N Antibodies Using Combined Positive Scoring.

For patients with metastatic triple-negative breast cancer (TNBC), treatment with pembrolizumab is dependent on the accurate determination of programmed death ligand 1 (PD-L1) expression using immunohistochemistry (IHC). This study evaluated the interobserver concordance in assessing PD-L1 expression on TNBC samples using the commercial 22C3 IHC assay and an in-house assay based on the E1L3N antibody. Concordance between the 22C3 and the E1L3N IHC assays was evaluated on TNBC samples read by a commercial laboratory and a Brigham and Women's Hospital breast pathologist (BWH reader). Each slide was given a PD-L1 combined positive score (CPS) and was considered PD-L1 positive or negative based on the CPS cutoff of 10. Interobserver concordance for the assays was also evaluated on a subset of samples between 2 and 3 independent readers. On 71 samples, 2 independent readers (1 BWH reader and commercial laboratory) using E1L3N and 22C3, respectively, reached agreement on PD-L1 status (positive/negative) on 64 samples (90.1%). Using 22C3, 2 independent readers reached agreement on PD-L1 status on 30 of 36 samples (83.3%), and 3 independent readers reached agreement on 16 of 27 samples (59.3%). Using E1L3N, 2 BWH readers reached agreement on PD-L1 status on 18 of 27 samples (66.7%). Three BWH readers reached an agreement on 2 of 12 of the most challenging samples (16.7%). In conclusion, concordance between E1L3N and 22C3 testing using CPS for PD-L1 in metastatic TNBC was >90%. However, certain cases were challenging to agree upon using current threshold criteria, highlighting the need for more standardized evidence-based methods to assess PD-L1 expression.

AKT and EZH2 inhibitors kill TNBCs by hijacking mechanisms of involution.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and has the highest rate of recurrence1. The predominant standard of care for advanced TNBC is systemic chemotherapy with or without immunotherapy; however, responses are typically short lived1,2. Thus, there is an urgent need to develop more effective treatments. Components of the PI3K pathway represent plausible therapeutic targets; more than 70% of TNBCs have alterations in PIK3CA, AKT1 or PTEN3-6. However, in contrast to hormone-receptor-positive tumours, it is still unclear whether or how triple-negative disease will respond to PI3K pathway inhibitors7. Here we describe a promising AKT-inhibitor-based therapeutic combination for TNBC. Specifically, we show that AKT inhibitors synergize with agents that suppress the histone methyltransferase EZH2 and promote robust tumour regression in multiple TNBC models in vivo. AKT and EZH2 inhibitors exert these effects by first cooperatively driving basal-like TNBC cells into a more differentiated, luminal-like state, which cannot be effectively induced by either agent alone. Once TNBCs are differentiated, these agents kill them by hijacking signals that normally drive mammary gland involution. Using a machine learning approach, we developed a classifier that can be used to predict sensitivity. Together, these findings identify a promising therapeutic strategy for this highly aggressive tumour type and illustrate how deregulated epigenetic enzymes can insulate tumours from oncogenic vulnerabilities. These studies also reveal how developmental tissue-specific cell death pathways may be co-opted for therapeutic benefit.

A phase II study of atezolizumab, pertuzumab, and high-dose trastuzumab for central nervous system metastases in patients with HER2-positive breast cancer.

PURPOSE: Patients with HER2-positive breast cancer brain metastases have few effective systemic therapy options. In a prior study, pertuzumab with high-dose trastuzumab demonstrated a high clinical benefit rate (CBR) in the central nervous system (CNS) in patients with brain metastases. The current trial evaluated whether the addition of atezolizumab to this regimen would produce further improvements in CNS response. PATIENTS AND METHODS: This was a single-arm, multi-center, phase II trial of atezolizumab, pertuzumab, and high-dose trastuzumab for patients with HER2-positive breast cancer brain metastases. Participants received atezolizumab 1200 mg IV every 3 weeks (q3w), pertuzumab (loading dose 840 mg IV, then 420 mg IV q3w), and high-dose trastuzumab (6 mg/kg IV weekly for 24 weeks, then 6 mg/kg IV q3w). The primary endpoint was CNS overall response rate (ORR) per Response Assessment in Neuro-Oncology Brain Metastases (RANO-BM) criteria. Key secondary endpoints included CBR, overall survival (OS), and safety and tolerability of the combination. RESULTS: Among 19 enrolled participants, two had a confirmed intracranial partial response for a CNS-ORR of 10.5% (90% CI: 1.9%-29.6%). The study did not meet the prespecified efficacy threshold and was terminated early. The CBR was 42.1% at 18 weeks and 31.6% at 24 weeks. Seven patients (36.8%) required a dose delay or hold, and the most frequent any-grade adverse events were diarrhea (26.3%) and fatigue (26.3%). CONCLUSIONS: The addition of atezolizumab to pertuzumab plus high-dose trastuzumab does not result in improved CNS responses in patients with HER2-positive breast cancer brain metastases.

Heterogeneity of Residual Disease After Neoadjuvant Systemic Therapy in Breast Cancer: A Review.

Importance: Over the past 2 decades, systemic therapy for early-stage breast cancer has gradually moved from the adjuvant to the neoadjuvant setting. Administration of systemic therapy before surgery leads to potential improvements in surgical outcomes and allows for the assessment of the pathologic response to treatment. For patients with residual disease (RD), 3 adjuvant strategies have been shown to improve outcomes: (1) adjuvant trastuzumab emtansine for ERBB2-positive disease, (2) adjuvant capecitabine for triple-negative disease, and (3) adjuvant olaparib for patients with germline BRCA variants. Furthermore, studies are testing novel drugs in the postneoadjuvant setting. Given the potential to tailor adjuvant therapy based on the response to preoperative systemic therapy, recognizing the complexities of response to neoadjuvant therapy and moving beyond the binary paradigm of RD vs experiencing a pathologic complete response is becoming increasingly necessary. Observations: Novel antibody-drug conjugates, anti-ERBB2 tyrosine kinase inhibitors, and immune checkpoint inhibitors are being evaluated as additional rescue options in phase 3 trials for patients with RD after neoadjuvant treatment. Concomitantly, the prognostic role of RD has been refined by the introduction of the residual cancer burden. In addition, the genomic landscape of RD has been found to be associated with long-term prognosis, as has the immune background of the disease evaluated via the presence of tumor-infiltrating lymphocytes. Lastly, the dynamics of circulating tumor DNA may allow for further improvement in prognostication by understanding which patients harbor detectable minimal RD. Conclusions and Relevance: Escalating adjuvant treatment has led to meaningful survival improvements among patients with breast cancer and RD after neoadjuvant therapy. Uncovering the anatomic and biological intricacies of RD will allow for increased precision in postneoadjuvant treatments, moving beyond the binary paradigm of RD vs pathologic complete response, toward more tailored rescue strategies in the adjuvant setting.

Summary of quality of life in the ASCENT phase 3 clinical trial for people with metastatic triple-negative breast cancer.

WHAT IS THIS SUMMARY ABOUT?: A medicine called sacituzumab govitecan (brand name TRODELVY®) has been proven to be an effective treatment for metastatic triple-negative breast cancer (mTNBC for short). Metastatic breast cancer is cancer that has spread to other parts of the body. In mTNBC, the breast cancer cells do not have 3 common proteins on the cell surface, called receptors. mTNBC is more difficult to treat and more likely to come back than other types of breast cancer. The ASCENT study showed that participants with mTNBC treated with sacituzumab govitecan had a higher likelihood of living longer and delayed progression (worsening) of their cancer than those treated with standard chemotherapy. Here, we summarize the quality of life of participants with mTNBC in the ASCENT study. We compared quality of life between 236 participants treated with sacituzumab govitecan and 183 participants treated with standard chemotherapy. All participants previously received 2 or more chemotherapies that no longer controlled their cancer. WHAT ARE THE KEY TAKEAWAYS?: This analysis showed that participants treated with sacituzumab govitecan had better overall quality of life than participants treated with standard chemotherapy. They also had better "physical functioning", which is the ability to walk and do physical activities. Participants treated with sacituzumab govitecan maintained their overall quality of life for a longer time than those treated with standard chemotherapy. Participants treated with sacituzumab govitecan had less pain and were less tired than those treated with standard chemotherapy. On the other hand, participants treated with sacituzumab govitecan had worse diarrhea (loose or watery stools) and were more likely to have nausea/vomiting (feel sick or throw up) than participants treated with standard chemotherapy. WHAT WERE THE MAIN CONCLUSIONS REPORTED BY THE RESEARCHERS?: Participants treated with sacituzumab govitecan had a higher likelihood of living longer and delayed progression (worsening) of their cancer. Participants also had a better overall quality of life, which was maintained (did not get worse) for a longer time. However, they experienced worsening of diarrhea and/or nausea/vomiting.Clinical Trial Registration: NCT02574455 (ASCENT) (ClinicalTrials.gov).

Association between pembrolizumab-related thyroid adverse events and outcomes in early-stage triple-negative breast cancer patients.

Pembrolizumab-related thyroid dysfunction has been associated with better outcomes in metastatic cancer patients. This study aims to examine the outcomes (pathological complete response (pCR) and event-free survival (EFS)) in early-stage triple-negative breast cancer (TNBC) patients receiving preoperative therapy who developed pembrolizumab-related thyroid dysfunction. Patients were divided into four groups based on the occurrence or not of pembrolizumab-related thyroid dysfunction (group A and D, respectively) and, in case of pre-existing thyroid disorder, based on the need for levothyroxine start/adjustment or not (group B and C, respectively). pCR and EFS in groups A, B, and C were compared to the ones in group D. Sixty-four early-stage TNBC patients were included, and the median follow-up was 16.5 months (IQR 12.0-23.8). Multiple patterns of thyroid irAEs were observed (overt hypothyroidism in 56.3%, subclinical thyrotoxicosis in 28.1%, overt thyrotoxicosis and subclinical hypothyroidism in 21.9%, and 21.9% of patients). No statistical difference was found in pCR (chi-square test, P = 0.611) comparing groups A, B, and C to group D. The median EFS in groups A, B, and C and in group D were 16.5 (IQR 12.0-24.0) and 16.0 (IQR 12.0-22.3) months, respectively (log-rank test, P = 0.671). The percentage of patients obtaining pCR was 85.7% in patients developing pembrolizumab-related overt thyrotoxicosis and 42.1% in remaining patients (chi-square test, P = 0.036). The EFS was 16.0 months (IQR 12.0-25.0) in patients developing pembrolizumab-related overt thyrotoxicosis and 16.0 months (IQR 12.0-23.5) in the remaining patients (log-rank test, P = 0.494). In conclusion, multiple patterns of pembrolizumab-related thyroid dysfunction occur in early-stage TNBC. Patients developing pembrolizumab-related overt thyrotoxicosis are more likely to achieve pCR.

Dual HER2 inhibition: mechanisms of synergy, patient selection, and resistance.

HER2-targeted therapies for patients with HER2+ breast cancer are rapidly evolving, offering a range of more complex and personalized treatment options. Currently, an array of anti-HER2 monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates are administered, sometimes alongside chemotherapy or endocrine therapy, both in curative and palliative contexts. However, the heterogeneous nature of HER2+ breast cancer demands a deeper understanding of disease biology and its role in responsiveness to novel HER2-targeted agents, as well as non-HER2-targeted therapies, in order to optimize patient outcomes. In this Review, we revisit the mechanisms of action of HER2-targeted agents, examine the evidence supporting the use of dual HER2 blockade in patients with HER2-amplified tumours, and explore the role of biomarkers in guiding future treatment strategies. We also discuss potential implications for the future treatment of patients with HER2+ breast cancer.

Integrative Multiomic Profiling of Triple-Negative Breast Cancer for Identifying Suitable Therapies.

PURPOSE: Triple-negative breast cancer (TNBC) is a heterogeneous disease that carries the poorest prognosis of all breast cancers. Although novel TNBC therapies in development are frequently targeted toward tumors carrying a specific genomic, transcriptomic, or protein biomarker, it is poorly understood how these biomarkers are correlated. EXPERIMENTAL DESIGN: To better understand the molecular features of TNBC and their correlation with one another, we performed multimodal profiling on a cohort of 95 TNBC. Our approach involved quantifying tumor-infiltrating lymphocytes through hematoxylin and eosin staining, assessing the abundance of retinoblastoma, androgen receptor, and PDL1 proteins through IHC, and carrying out transcriptomic profiling using the NanoString BC360 platform, targeted DNA sequencing on a subset of cases, as well as evaluating associations with overall survival. RESULTS: Levels of RB1 mRNA and RB proteins are better correlated with markers of retinoblastoma functionality than RB1 mutational status. Luminal androgen receptor tumors clustered into two groups with transcriptomes that cluster with either basal or mesenchymal tumors. Tumors classified as PDL1-positive by the presence of immune or tumor cells showed similar biological characteristics. HER2-low TNBC showed no distinct biological phenotype when compared with HER2-zero. The majority of TNBC were classified as basal or HER2-enriched by PAM50, the latter showing significantly improved overall survival. CONCLUSIONS: Our study contributes new insights into biomarker utility for identifying suitable TNBC therapies and the intercorrelations between genomic, transcriptomic, protein, and cellular biomarkers. Additionally, our rich data resource can be used by other researchers to explore the interplay between DNA, RNA, and protein biomarkers in TNBC.

Analysis of HER2 expression changes from breast primary to brain metastases and the impact of HER2-low expression on overall survival.

BACKGROUND: There are limited data regarding HER2-low expression dynamics between matched primary tumors and brain metastases (BrMs) in breast cancer. HER2-low expression has emerged as a new therapeutic biomarker for highly active antibody-drug conjugates with emerging intracranial activity. METHODS: Patients with metastatic breast cancer (MBC) and BrMs seen at an NCI-designated center between 2003-2023 were identified. HER2 expression was defined as HER2-positive (3+,2+/ISH amplified), HER2-low (1+,2+/ISH negative), or HER2-0 by ASCO-CAP guidelines. Estrogen receptor (ER) status was defined as ER≥1%. Multivariate survival analyses by Cox proportional hazard models were determined from time of BrM resection to death or last follow-up between the 3 subtypes, controlling for ER and age. RESULTS: Among 197 matched primary and resected BrMs, 81% exhibited HER2 expression in the brain:61% HER2-positive, 20% HER2-low, and 19% HER2-0. Concordance was high in HER2-positive primary tumors with 100% retaining HER2 expression (97% retained HER2+ expression and 2.7% switched to HER2-low). HER2-0 primaries frequently showed HER2 gain in BrMs to HER2-low (35%) or HER2-positive (5.4%) status. Among 48 HER2-low primary tumors, 52% were discordant for HER2 status in the brain with 21% testing HER2-positive and 31% testing HER2-0. In adjusted analyses, patients with HER2-positive BrMs had significantly lower death risk than patients with HER2-low BrMs (HR=0.41, P=0.0006); no difference was observed between HER2-0 and HER2-low. CONCLUSIONS: In this retrospective analysis, HER2 expression is common in breast cancer BrMs, emphasizing the need for improved, non-invasive diagnostics. Patients with HER2-low and HER2-0 BrMs face inferior survival, presenting an unmet clinical need.

Globalization of clinical research in oncology: Status, challenges, and future directions.

PURPOSE: Cancer is the second-leading cause of death worldwide, and its burden is increasing around the world, particularly in low- and middle-income countries (LMICs). Yet, cancer research has historically been conducted primarily in high-income countries (HICs). METHODS: In this review, we describe the results of our literature search into the current state of international cancer trials, including the benefits, challenges, limitations, and ethical concerns regarding the international conduct of HIC-led trials. We also propose some possible means of addressing these challenges and overcoming these barriers to extend the benefits of cancer research to people around the world. RESULTS: Over the last several decades, there has been a shift toward inclusion of investigators and participants from LMICs in pivotal cancer clinical trials. CONCLUSIONS: While inclusion of LMIC countries has benefits, including increased diversity of participant populations, investment in research infrastructure in LMICs, and potential expansion of cancer treatment options around the world, the continued leadership of most trials by HICs presents ethical concerns, including potential exploitation of researchers and participants from LMICs, lack of focus on cancer types prevalent in all participating regions, and disparities in access to approved therapies once the trial is complete.

Subcutaneous vs Intravenous Trastuzumab/Pertuzumab: A Time and Motion Substudy of a Phase II Trial of Adjuvant Trastuzumab/Pertuzumab for Stage I HER2+ Breast Cancer (ADEPT trial).

PURPOSE: The time required for in-clinic drug administration can substantially affect breast cancer patients' quality of life. Subcutaneous (SC) drug administration, as opposed to intravenous (IV), may reduce this time commitment. This study sought to estimate the difference in time burden between IV and SC administration of trastuzumab and pertuzumab (HP). METHODS: We prospectively enrolled a subcohort of patients participating in the ADEPT trial (ClinicalTrials.gov identifier: NCT04569747, investigating adjuvant HP plus endocrine therapy for stage I human epidermal growth factor receptor 2-positive breast cancer) to this single-arm crossover time and motion substudy. Patients received two cycles of IV HP followed by two cycles of SC HP. During each cycle, time points in drug preparation and administration were captured. The primary end point was total patient time in the treatment chair. Additional end points included total patient treatment experience time and total pharmacy workflow time. A sample size of 22 patients was estimated to provide 90.7% power with two-sided alpha .05 to detect a difference of 70 minutes in the primary end point by treatment arm (IV v SC). RESULTS: Twenty-two patients were enrolled. The mean total patient time in the treatment chair was 61.8 minutes shorter with SC versus IV HP (22.5 v 84.3 minutes; P < .0001). The mean total patient treatment experience time (incorporating time spent waiting for treatment initiation and time spent in the treatment chair) was 81.8 minutes shorter for SC administration (96 v 177.8 minutes; P < .0001). The pharmacy workflow time was 78.2 minutes shorter for SC versus IV formulation (41 v 119.2 minutes; P < .0001). CONCLUSION: SC administration of HP shortened patient time burden by approximately 1 hour. SC drug administration can facilitate faster workflows for health care professionals and improve patients' breast cancer treatment experience.

Abemaciclib plus endocrine therapy for HR+, HER2-, node-positive, high-risk early breast cancer: a plain language summary of the monarchE study.

WHAT IS THIS SUMMARY ABOUT?: This article summarizes the most recent results of the monarchE study. This study was completed in participants with a type of breast cancer called HR+, HER2-, node-positive, high-risk early breast cancer. In this study, abemaciclib, a non-chemotherapy treatment, was administered with standard of care endocrine therapy after curative surgery. Most participants had received prior chemotherapy and/or radiotherapy. The study investigated if abemaciclib helped participants live longer without their cancer returning compared with participants who only received standard of care endocrine therapy. The study participants were assigned to 1 of 2 treatment groups. Participants in Group A were assigned to receive standard of care endocrine therapy with abemaciclib for 2 years, followed by endocrine therapy for a total of at least 5 years. Participants in Group B were assigned to receive standard of care endocrine therapy only for at least 5 years. The effect of treatment was compared between these 2 groups. WHAT WERE THE RESULTS?: Overall, the results showed that the cancer was 34% less likely to come back after surgery in the participants in Group A (abemaciclib plus endocrine therapy) compared with those in Group B (endocrine therapy only). At 4 years since the start of the study treatment, more participants who received the combination of abemaciclib plus endocrine therapy remained free of cancer compared with participants who received endocrine therapy alone (86% versus 79%). Participants who received abemaciclib plus endocrine therapy had more side effects than those who received endocrine therapy alone, but most of these effects were mild to moderate and reversible upon the end of therapy. The most common side effects in the abemaciclib group were diarrhea, infections, low number of white blood cells, and tiredness. WHAT DO THE RESULTS MEAN?: This study found that administering abemaciclib in combination with standard endocrine therapy after curative breast surgery helped lower the risk of cancer returning in people with HR+, HER2-, node-positive, high-risk early breast cancer. Abemaciclib is a new treatment option for people with this diagnosis. People with high-risk early breast cancer should always talk to their doctors and nurses before making any decisions about their treatment.Clinical Trial Registration: NCT03155997 (monarchE study).

Checkpoint inhibition for early-stage hormone receptor-positive breast cancer.

INTRODUCTION: Most patients with breast cancer have early-stage hormone receptor (HR)-positive, human epidermal growth factor receptor-2 (HER2)-negative disease. Even though the prognosis for most of these patients is good, there is a need to identify patients at risk for poor outcomes and to develop strategies to mitigate this risk. AREAS COVERED: The addition of immunotherapy to standard neoadjuvant chemotherapy represents a promising option for select patients with HR-positive early breast cancer. Three randomized clinical trials have shown favorable results to date. In this review, we discuss the findings of I-SPY2, CheckMate 7FL (NCT04109066), and KEYNOTE-756 (NCT03725059). EXPERT OPINION: Despite the promising results of these trials, there are unanswered questions that need to be considered before incorporating neo/adjuvant immunotherapy in the treatment paradigm of early-stage HR-positive breast cancer. One example of an unanswered question is patient selection. Because the regimens used in these protocols are associated with long-term toxicities, identifying the patients who are more likely to derive a benefit from these agents, such as through the use of biomarkers, is critical. A second example is the optimal integration of adjuvant therapies that improve invasive disease-free survival, such as abemaciclib and ribociclib, which are not safely administered concurrently with immunotherapy.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel Plus Trastuzumab for Stage I Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: 5-Year Results and Correlative Analyses From ATEMPT.

PURPOSE: Long-term outcomes of patients with stage I human epidermal growth factor receptor 2 (HER2)-positive breast cancer receiving adjuvant trastuzumab emtansine (T-DM1) remain undefined, and prognostic predictors represent an unmet need. METHODS: In the ATEMPT phase II trial, patients with stage I centrally confirmed HER2-positive breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for 1 year or paclitaxel plus trastuzumab (TH). Coprimary objectives were to compare the incidence of clinically relevant toxicities between arms and to evaluate invasive disease-free survival (iDFS) with T-DM1. Correlative analyses included the HER2DX genomic tool, multiomic evaluations of HER2 heterogeneity, and predictors of thrombocytopenia. RESULTS: After a median follow-up of 5.8 years, 11 iDFS events were observed in the T-DM1 arm, consistent with a 5-year iDFS of 97.0% (95% CI, 95.2 to 98.7). At 5 years, the recurrence-free interval (RFI) was 98.3% (95% CI, 97.0 to 99.7), the overall survival was 97.8% (95% CI, 96.3 to 99.3), and the breast cancer-specific survival was 99.4% (95% CI, 98.6 to 100). Comparable iDFS was observed with T-DM1 irrespective of tumor size, hormone receptor status, centrally determined HER2 immunohistochemical score, and receipt of T-DM1 for more or less than 6 months. Although ATEMPT was not powered for this end point, the 5-year iDFS in the TH arm was 91.1%. Among patients with sufficient tissue for HER2DX testing (n = 187), 5-year outcomes significantly differed according to HER2DX risk score, with better RFI (98.1% v 81.8%, hazard ratio [HR], 0.10, P = .01) and iDFS (96.3% v 81.8%, HR, 0.20, P = .047) among patients with HER2DX low-risk versus high-risk tumors, respectively. CONCLUSION: Adjuvant T-DM1 for 1 year leads to outstanding long-term outcomes for patients with stage I HER2-positive breast cancer. A high HER2DX risk score predicted a higher risk of recurrence in ATEMPT.