HER2‐positive breast cancer brain metastasis: A new and exciting landscape

Demographic and clinical characteristics of patients with metastatic breast cancer and leptomeningeal disease: a single center retrospective cohort study

PURPOSE

Leptomeningeal disease (LMD) is a devastating complication of metastatic breast cancer (MBC). It is critical to better understand the risk factors, natural history, and treatment outcomes, including patients in a modern cohort.

METHODS

In this single center retrospective cohort study, we identified patients with MBC and LMD who received care from 2000 to 2024 and abstracted key clinical, treatment, and survival data.

RESULTS

We identified 111 patients with MBC and LMD, including patients with the following subtypes: HR+/HER2- (n = 53, 47.7%), HER2+ (n = 30, 27.0%), and triple negative breast cancer (TNBC; n = 28, 25.2%). Median time from the diagnosis of MBC to LMD was 16.4 months (range 0-101.3 months). After the diagnosis of LMD, most patients received systemic therapy (n = 66, 59.5%) and/or central nervous system (CNS)-directed therapy (n = 94, 84.7%) including intrathecal therapy (n = 42, 37.8%) and/or CNS-directed radiation therapy (n = 70, 63.1%). In all patients, median overall survival (OS) from the diagnosis of LMD to death was 4.1 months (range 0.1-78.1 months) and varied by subtype, with HR+/HER2- or HER2+ MBC patients living longer than those with TNBC (4.2 and 6.8 months respectively vs. 2.0 months, p < 0.01, HR 2.15, 95% CI 1.36-3.39). Patients who received CNS-directed therapy lived longer than those who did not (4.2 vs. 1.3, p = 0.02 HR 0.54, 0.32-0.91). Patients diagnosed with LMD from 2015 to 2024 lived longer than those diagnosed from 2000 to 2014 (6.4 vs. 2.9 months, p = 0.04, HR 0.67, 95% CI 0.46-0.99). On multivariable analysis, having TNBC was associated with shorter OS from time of LMD to death (p = 0.004, HR 2.03, 95% CI 1.25-3.30).

CONCLUSION

This is one of the largest case series of patients with MBC and LMD. Patients diagnosed with LMD from 2015 to 2024 lived longer than those diagnosed from 2000 to 2014, although median OS was short overall. Patients with TNBC and LMD had particularly short OS. Novel therapeutic strategies for LMD remain an area of unmet clinical need.

State of the Art Modelling of the Breast Cancer Metastatic Microenvironment: Where Are We?

Metastatic spread of tumour cells to tissues and organs around the body is the most frequent cause of death from breast cancer. This has been modelled mainly using mouse models such as syngeneic mammary cancer or human in mouse xenograft models. These have limitations for modelling human disease progression and cannot easily be used for investigation of drug resistance and novel therapy screening. To complement these approaches, advances are being made in ex vivo and 3D in vitro models, which are becoming progressively better at reliably replicating the tumour microenvironment and will in the future facilitate drug development and screening. These approaches include microfluidics, organ-on-a-chip and use of advanced biomaterials. The relevant tissues to be modelled include those that are frequent and clinically important sites of metastasis such as bone, lung, brain, liver for invasive ductal carcinomas and a distinct set of common metastatic sites for lobular breast cancer. These sites all have challenges to model due to their unique cellular compositions, structure and complexity. The models, particularly in vivo, provide key information on the intricate interactions between cancer cells and the native tissue, and will guide us in producing specific therapies that are helpful in different context of metastasis.

A Case Report on Trastuzumab Emtansine (T-DM1) in a Patient With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Metastatic Breast Cancer and Brain Metastases: Long-Term Treatment and Survival

Breast cancer remains the most common cancer in women worldwide. Among women with breast cancer, brain metastases are very prevalent among HER2-positive and affect those in the advanced stages of the disease. Various factors, including molecular subtypes, performance status, extracranial disease status, leptomeningeal metastasis, and the number of lesions, significantly influence the prognosis of patients with brain metastases from breast cancer (BCBrM). Understanding and addressing the specific risks associated with different breast cancer subtypes is crucial for developing tailored and effective medical treatments. This report presents a case of a breast cancer patient with recurrent disease and brain metastases who achieved long-term survival following a treatment regimen that included radiotherapy and a T-DM1 biosimilar.

Subcutaneous Trastuzumab: An Observational Study of Safety and Tolerability in Patients With Early HER2-Positive Breast Cancer

Purpose: In Peru, breast cancer (BC) stands as the most predominant malignancy neoplasm among women. Trastuzumab has marked a significant milestone in the management of this disease. It has been shown to improve prognosis in human epidermal growth factor receptor 2 (HER2)-expressing female patients, but its repercussions and efficacy are yet to be analyzed in a context with limited resources. Methods: The study population is made of woman patients aged 18 years and older diagnosed with HER2-positive BC at Instituto Nacional de Enfermedades Neoplásicas (INEN, Lima, Peru) during 2019-2021 and treated with at least one dose of subcutaneous trastuzumab. We reviewed medical records to register treatment characteristics, adverse events (AEs), disease progression, and survival status. We considered a median follow-up time of 36 and 45 months for progression and survival status. Results: The majority of patients were over 50 years old (54.29%). Tumor size averaged 19.7 ± 16.1 mm. Lymph nodes were present in 44.78% of patients. Most patients received adjuvant chemotherapy (63.8%) as first-line treatment. Descriptive analyses of treatment outcomes revealed a 30% toxicity rate, primarily attributed to arthralgia (47.62%), followed by diarrhea, fatigue, and injection site reactions, with relatively lower discontinuation rates compared to larger scale studies. Differences in demographic, clinical, and treatment characteristics were not statistically significant concerning the emergence of AEs (p > 0.05). Progression appeared in nine patients, and the overall survival (OS) rate stood at 98.6% and 92.8%, respectively, during a median follow-up of 36 and 45 months. Conclusion: The research suggests that subcutaneous trastuzumab is comparable in effectiveness and safety to the intravenous administration. Regional-specific studies may provide valuable insights into demographic factors influencing treatment outcomes in Peru or other countries. Furthermore, it could represent a more accessible alternative, potentially enhancing patient adherence and optimizing healthcare resource logistics.

Association Between 18F-FDG PET Activity and HER2 Status in Breast Cancer Brain Metastases

Purpose

The objective of this study was to evaluate whether uptake on 18F-fluorodeoxyglucose (18F-FDG) PET could help differentiate HER2-positive from HER2-negative breast cancer brain metastases.

Methods

In this retrospective, cross-sectional study of a cohort of 14 histologically proven breast cancer brain metastases, we analyzed both preoperative 18F-FDG PET/CT and HER2 status of the resected/biopsied brain specimens. The maximum standardized uptake values (SUVmax) of the lesions were normalized to contralateral normal white matter and compared using Mann-Whitney U tests.

Results

The study cohort was comprised of 12 women with breast cancer with a mean age of 59 years (range: 43-76 years) with a total of 14 distinct brain metastatic lesions. The SUVmax ratio of HER2-positive breast cancer brain metastases was significantly greater than that of HER2-negative lesions (3.98 vs 1.79, U = 38.00, p = 0.008).

Conclusion

The SUVmax ratio may help to identify the HER2 status of breast cancer brain metastases, if validated prospectively.

Electrophysiological and morphological modulation of neuronal-glial network by breast cancer and nontumorigenic mammary cell conditioned medium

Breast cancer is a significant global health concern, with the overexpression of human epidermal growth factor receptor 2 (HER2/ERBB2) being a driver oncogene in 20%-30% of cases. Indeed, HER2/ERBB2 plays a crucial role in regulating cell growth, differentiation, and survival via a complex signaling network. Overexpression of HER2/ERBB2 is associated with more aggressive behavior and increased risk of brain metastases, which remains a significant clinical challenge for treatment. Recent research has highlighted the role of breast cancer secretomes in promoting tumor progression, including excessive proliferation, immune invasion, and resistance to anti-cancer therapy, and their potential as cancer biomarkers. In this study, we investigated the impact of ERBB2+ breast cancer SKBR-3 cell line compared with MCF10-A mammary non-tumorigenic cell conditioned medium on the electrophysiological activity and morphology of neural networks derived from neurons differentiated from human induced pluripotent stem cells. Our findings provide evidence of active modulation of neuronal-glial networks by SKBR-3 and MCF10-A conditioned medium. These results provide insights into the complex interactions between breast cancer cells and the surrounding microenvironment. Further research is necessary to identify the specific factors within breast cancer conditioned medium that mediate these effects and to develop targeted therapies that disrupt this interaction.

Clinical Outcomes of Patients with HER2 Positive Metastatic Breast Cancer to the Brain, with First-Line Trastuzumab, Pertuzumab and Chemotherapy, in a Real-World Setting

Background

In this observational study, we analyzed the treatment patterns and clinical outcomes of patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC) who developed brain metastases during their disease in a 2.7 million-member public health-provider in Israel.

Methods

Newly diagnosed patients with mBC who initiated first-line treatment between January 2013 and June 2021 were identified. Time on treatment (ToT) and overall survival (OS) were assessed at a minimum of 6 months follow-up (cutoff: December 2021).

Results

We identified a total of 61 patients: 98.4% females, median age 50 years (IQR = 44-63), 85% invasive ductal tumors, 44% hormone receptor positive, 51% performance status 0-1. The median duration of follow-up was 6.2 years. All patients initiated a combination treatment of trastuzumab, pertuzumab, and chemotherapy (TPC), and 72% moved to second-line treatment during the study follow-up period (82% ado-trastuzumab emtansine). The median ToT for first-line and second-line treatments were 16.9 months (95% CI = 13.9-27.7) and 7.9 months (95% CI = 5.6-10.9), respectively. The median overall survival (OS) was 45.5 months (95% CI = 35.4-71.2) from the initiation of first-line treatment. When considering the timing of brain metastases, the median OS was 36.3 months (95% CI = 10.0-NR) for those diagnosed upfront (n = 15, 25%), 59.1 months (95% CI = 32.5-NR) for those diagnosed while on TPC (n = 25, 41%), and 40.8 months (95% CI = 35.4-NR) for those diagnosed at a later stage (n = 21, 34%). The median OS from brain metastases diagnosis was 25.1 months (95% CI = 17.0-34.6).

Conclusion

Patients with upfront brain involvement at the time of mBC diagnosis had shorter survival compared to those who started TPC without brain metastases. Nonetheless, the overall results from this study compare favorably with previous studies and contribute to understanding the value of traditional treatment options, which will serve as a baseline for future treatment strategies in the real-world setting.

Standard-of-Care Treatment for HER2+ Metastatic Breast Cancer and Emerging Therapeutic Options

Prior to the advent of the HER2-targeted monoclonal antibody trastuzumab, HER2+ breast cancer (BC) was considered an aggressive disease with a poor prognosis. Over the past 25 years, innovations in molecular biology, pathology, and early therapeutics have transformed the treatment landscape. With the advent of multiple HER2-directed therapies, there have been immense improvements in oncological outcomes in both adjuvant and metastatic settings. Currently, 8 HER2-targeted therapies are approved by the Food and Drug Administration (FDA) for the treatment of early-stage and/or advanced/metastatic disease. Nonetheless, approximately 25% of patients develop recurrent disease or metastasis after HER2-targeted therapy and most patients with HER2+ metastatic breast cancer (MBC) die from their disease. Given the many mechanisms of resistance to HER2-directed therapy, there is a pressing need to further personalize care for patients with HER2+ MBC, by the identification of reliable predictive biomarkers, and the development of novel therapies and combination regimens to overcome therapeutic resistance. Of particular interest are established and novel antibody-drug conjugates, as well as other novel therapeutics and multifaceted approaches to harness the immune system (checkpoint inhibitors, bispecific antibodies, and vaccine therapy). Herein, we discuss standard-of-care treatment of HER2+ MBC, including the management of breast cancer brain metastases (BCBM). Furthermore, we highlight novel treatment approaches for HER2+ MBC, including endeavors to personalize therapy, and discuss ongoing controversies and challenges.

Overcoming brain-derived therapeutic resistance in HER2+ breast cancer brain metastasis

Brain metastasis of HER2+ breast cancer occurs in about 50% of all women with metastatic HER2+ breast cancer and confers poor prognosis for patients. Despite effective HER2-targeted treatments of peripheral HER2+ breast cancer with Trastuzumab +/-HER2 inhibitors, limited brain permeability renders these treatments inefficient for HER2+ breast cancer brain metastasis (BCBM). The scarcity of suitable patient-derived in-vivo models for HER2+ BCBM has compromised the study of molecular mechanisms that promote growth and therapeutic resistance in brain metastasis. We have generated and characterized new HER2+ BCBM cells (BCBM94) isolated from a patient HER2+ brain metastasis. Repeated hematogenic xenografting of BCBM94 consistently generated BCBM in mice. The clinically used receptor tyrosine kinase inhibitor (RTKi) Lapatinib blocked phosphorylation of all ErbB1-4 receptors and induced the intrinsic apoptosis pathway in BCBM94. Neuregulin-1 (NRG1), a ligand for ErbB3 and ErbB4 that is abundantly expressed in the brain, was able to rescue Lapatinib-induced apoptosis and clonogenic ability in BCBM94 and in HER2+ BT474. ErbB3 was essential to mediate the NRG1-induced survival pathway that involved PI3K-AKT signalling and the phosphorylation of BAD at serine 136 to prevent apoptosis. High throughput RTKi screening identified the brain penetrable Poziotinib as highly potent compound to reduce cell viability in HER2+ BCBM in the presence of NRG1. Successful in-vivo ablation of BCBM94- and BT474-derived HER2+ brain tumors was achieved upon two weeks of treatment with Poziotinib. MRI revealed BCBM remission upon poziotinib, but not with Lapatinib treatment. In conclusion, we have established a new patient-derived HER2+ BCBM in-vivo model and identified Poziotinib as highly efficacious RTKi with excellent brain penetrability that abrogated HER2+ BCBM brain tumors in our mouse models.

Emerging Landscape of Targeted Therapy of Breast Cancers With Low Human Epidermal Growth Factor Receptor 2 Protein Expression

CONTEXT.—

Human epidermal growth factor receptor 2 (HER2) status in breast cancer is currently classified as negative or positive for selecting patients for anti-HER2 targeted therapy. The evolution of the HER2 status has included a new HER2-low category defined as an HER2 immunohistochemistry score of 1+ or 2+ without gene amplification. This new category opens the door to a targetable HER2-low breast cancer population for which new treatments may be effective.

OBJECTIVE.—

To review the current literature on the emerging category of breast cancers with low HER2 protein expression, including the clinical, histopathologic, and molecular features, and outline the clinical trials and best practice recommendations for identifying HER2-low-expressing breast cancers by immunohistochemistry.

DATA SOURCES.—

We conducted a literature review based on peer-reviewed original articles, review articles, regulatory communications, ongoing and past clinical trials identified through ClinicalTrials.gov, and the authors' practice experience.

CONCLUSIONS.—

The availability of new targeted therapy potentially effective for patients with breast cancers with low HER2 protein expression requires multidisciplinary recognition. In particular, pathologists need to recognize and identify this category to allow the optimal selection of patients for targeted therapy.

Brain Metastases in the Setting of Stable Versus Progressing Extracranial Disease Among Patients With Metastatic Breast Cancer

INTRODUCTION

Women with metastatic breast cancer (BC) are at risk of developing brain metastases (BrM), which may result in significant morbidity and mortality. Given the emergence of systemic therapies with activity in the brain, more breast oncology clinical trials include patients with BrM, but most require extracranial disease progression for trial participation.

METHODS

We evaluated the proportion of patients with BC BrM who have intracranial disease progression in the setting of stable extracranial disease in a retrospective cohort study of 751 patients treated between 2008 and 2018 at the Sunnybrook Odette Cancer. Extracranial disease progression was defined as any progression outside of the brain within 4 weeks of a patient's local/regional treatment. Clinical/pathologic characteristics and outcomes were also abstracted from patients' medical records.

RESULTS

Of 752 patients in the cohort, 691 were included in our study. Sixty-one patients were excluded due to the presence of a second primary tumor or uncertain tissue origin of the BrM. BC subtype based on the primary tumor was known for 592 (85.6%) patients; 33.1% (n = 196) had HER2+ disease, 40% (n = 237) had HR+/HER2- disease, and 26.9% (n = 159) had triple negative BC. Extracranial disease status was available for 677 patients (98%); 41.1% (n = 284/691) had stable extracranial disease and 56.8% (n = 393/691) had extracranial disease progression within 4 weeks of treatment for BrM.

DISCUSSION

A high proportion of patients with BC BrM (41.1%) would be excluded from clinical trials due to stable extracranial disease. Efforts should be made to design trials for this patient population.

Impact of Clinical Examination and Gamma Knife Surgery in Stage IV Breast Cancer With Brain Metastasis

Metastatic breast cancer often presents with significant diagnostic and treatment challenges. This case report highlights the crucial role of thorough clinical examination and history-taking in diagnosing and managing a patient with metastatic breast cancer, mainly focusing on the successful integration of Gamma Knife radiosurgery (GKRS). We present a case of a 68-year-old postmenopausal woman with metastatic breast cancer, initially presenting with a primary tumour in the left breast and later developing a solitary brain metastasis (BM) in the left temporal lobe. Following neoadjuvant chemotherapy and left mastectomy, the patient experienced involuntary movements in the right arm, leading to the discovery of the brain lesion. Critical to this diagnosis was a detailed clinical examination emphasising the importance of vigilant monitoring in cancer management. The patient underwent GKRS, offering a focused and less invasive treatment approach with favourable outcomes. This case underscores the value of clinical vigilance in managing complex breast cancer cases. The integration of GKRS as a targeted treatment modality for BM represents a pivotal aspect of modern oncological care, especially for patients with multiple treatment modalities. This report emphasizes the importance of clinical examination in the early detection of complications such as BM in breast cancer patients. Furthermore, it demonstrates the effectiveness of GKRS in managing such metastases, reinforcing its role as a valuable tool in the multidisciplinary treatment approach for advanced breast cancer.

Pertuzumab plus high-dose trastuzumab for HER2-positive breast cancer with brain metastases: PATRICIA final efficacy data

The PATRICIA study (NCT02536339) examined the efficacy and safety of pertuzumab plus high-dose trastuzumab in patients with HER2-positive metastatic breast cancer (MBC) with progressive central nervous system (CNS) metastases following radiotherapy. Primary analysis confirmed CNS objective response rate (ORR) was 11% (95% confidence interval [CI]: 3-25); clinical benefit rate (CBR) was 68% (4 months) and 51% (6 months). We report final efficacy data after a further 21-months of follow-up, updated safety, survival, and patient-reported outcomes (PROs). Patients received standard-dose pertuzumab plus high-dose trastuzumab (6 mg/kg weekly) until CNS or systemic disease progression or unacceptable toxicity. Primary endpoint: confirmed ORR (CNS) per Response Assessment in Neuro-Oncology Brain Metastases criteria. Secondary endpoints were response duration, CBR, progression-free survival (PFS), overall survival (OS), safety, and PROs. By clinical cut-off, 39 patients had completed or discontinued treatment. Confirmed ORR (CNS) was 11% (95% CI: 3.0-25.4). Median CNS-PFS was 4.6 months (95% CI: 4.0-8.9), as was median CNS-PFS or systemic PFS (95% CI: 4.0-8.9); median OS was 27.2 months (95% CI: 16.1-not reached). CBR in the CNS was 51% (19 patients, 95% CI: 34.4-68.1) at 6 months. Two patients remained on treatment until study closure, achieving stable disease for 4.1 and 4.8 years. Treatment-related grade 3/4 adverse events occurred in 7.7% of patients. Patients with confirmed partial response or stable disease (≥4 months) in the CNS had stable PROs over time. Pertuzumab plus high-dose trastuzumab represents a reasonable non-chemotherapeutic treatment option for selected patients with HER2-positive MBC with CNS metastases.

Neratinib for HER2-positive breast cancer with an overlooked option

Positive human epidermal growth factor receptor 2 (HER2) expression is associated with an increased risk of metastases especially those to the brain in patients with advanced breast cancer (BC). Neratinib as a tyrosine kinase inhibitor can prevent the transduction of HER1, HER2 and HER4 signaling pathways thus playing an anticancer effect. Moreover, neratinib has a certain efficacy to reverse drug resistance in patients with BC with previous HER2 monoclonal antibody or targeted drug resistance. Neratinib, as monotherapy and in combination with other therapies, has been tested in the neoadjuvant, adjuvant, and metastatic settings. Neratinib with high anticancer activity is indicated for the prolonged adjuvant treatment of HER2-positive early BC, or in combination with other drugs including trastuzumab, capecitabine, and paclitaxel for the treatment of advanced HER2-positive BC especially cancers with central nervous system (CNS) metastasis to reduce the risk of BC recurrence. This article reviewed the pharmacological profiles, efficacy, safety, tolerability, and current clinical trials pertaining to neratinib, with a particular focus on the use of neratinib in patients with metastatic breast cancer (MBC) involving the CNS. We further discussed the use of neratinib for HER2-negative and HER2-mutant breast cancers, and mechanisms of resistance to neratinib. The current evidence suggests that neratinib has promising efficacy in patients with BC which is at least non-inferior compared to previous therapeutic regimens. The most common AE was diarrhea, and the incidence, severity and duration of neratinib-related grade 3 diarrhea can be reduced with loperamide. Of note, neratinib has the potential to effectively control and prevent brain metastasis in patients with advanced BC, providing a therapeutic strategy for HER2-positive BC.

HER2-Selective and Reversible Tyrosine Kinase Inhibitor Tucatinib Potentiates the Activity of T-DM1 in Preclinical Models of HER2-positive Breast Cancer

The oncogenic receptor HER2 is overexpressed in many cancers, including up to 20% of breast cancers. Despite the availability of HER2-targeted treatments, patients’ disease often progresses during therapy, underscoring the need for novel treatment strategies. The addition of tucatinib, a reversible, highly selective HER2 tyrosine kinase inhibitor (TKI), to treatment with trastuzumab and capecitabine significantly improved survival outcomes of patients with HER2-positive metastatic breast cancer, including those with active brain metastases. We rationalized that combining tucatinib with other HER2-targeting agents with complementary mechanisms of action would further increase efficacy against tumors. We characterized the activity of tucatinib with the antibody–drug conjugate T-DM1 in preclinical models of breast cancer, including HER2-positive breast cancer cells and patient-derived xenograft (PDX) models. Mechanistic details on tucatinib activity were obtained in internalization and catabolism studies. In combination, tucatinib and T-DM1 showed an enhanced, often synergistic, cytotoxic response and demonstrated improved antitumor activity in vivo, including in PDX models refractory to T-DM1 single-agent activity. Mechanistically, tucatinib mediated an increase in inactive HER2 molecules at the cell surface through inhibition of HER2 ubiquitination, resulting in increased internalization and catabolism of T-DM1. The combination was correlated with enhanced HER2 pathway inhibition, decreased proliferation, and increased apoptosis. In a xenograft model of brain metastasis, tucatinib penetrated intracranial tumor tissues, inhibiting tumor growth and improving survival. These results suggest that tucatinib may be the optimal TKI partner for HER2-targeted therapies and support clinical studies of its combination with T-DM1, including in patients with brain metastases.

SIGNIFICANCE

The preclinical findings in breast cancer models presented here demonstrate that combining tucatinib with T-DM1 enhances the antitumor activity of either agent alone, supporting clinical studies of the combination in HER2-positive breast cancer, including in patients with brain metastases, which remains an important unmet medical need.

Narrative Review of Multidisciplinary Management of Central Nervous Involvement in Patients with HER2-Positive Metastatic Breast Cancer: Focus on Elderly Patients

The tumor biology of human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) promotes the development of central nervous system (CNS) metastases, with 25% of patients with HER2-positive BC developing CNS metastases. Furthermore, the incidence of HER2-positive BC brain metastases has increased in the last decades, likely because of the improved survival with targeted therapies and better detection methods. Brain metastases are detrimental to quality of life and survival and represent a challenging clinical problem, particularly in elderly women, who comprise a substantial proportion of patients diagnosed with BC and often have comorbidities or an age-related decline in organ function. Treatment options for patients with BC brain metastases include surgical resection, whole-brain radiation therapy, stereotactic radiosurgery, chemotherapy, and targeted agents. Ideally, local and systemic treatment decisions should be made by a multidisciplinary team, with input from several specialties, based on an individualized prognostic classification. In elderly patients with BC, additional age-associated conditions, such as geriatric syndromes or comorbidities, and the physiologic changes associated with aging, may impact their ability to tolerate cancer therapy and should be considered in the treatment decision-making process. This review describes the treatment options for elderly patients with HER2-positive BC and brain metastases, focusing on the importance of multidisciplinary management, the different points of view from the distinct disciplines, and the role of oncogeriatric and palliative care in this vulnerable patient group.

Receptor-mediated drug delivery of bispecific therapeutic antibodies through the blood-brain barrier

Therapeutic antibody drug development is a rapidly growing sector of the pharmaceutical industry. However, antibody drug development for the brain is a technical challenge, and therapeutic antibodies for the central nervous system account for ~3% of all such agents. The principal obstacle to antibody drug development for brain or spinal cord is the lack of transport of large molecule biologics across the blood-brain barrier (BBB). Therapeutic antibodies can be made transportable through the blood-brain barrier by the re-engineering of the therapeutic antibody as a BBB-penetrating bispecific antibody (BSA). One arm of the BSA is the therapeutic antibody and the other arm of the BSA is a transporting antibody. The transporting antibody targets an exofacial epitope on a BBB receptor, and this enables receptor-mediated transcytosis (RMT) of the BSA across the BBB. Following BBB transport, the therapeutic antibody then engages the target receptor in brain. RMT systems at the BBB that are potential conduits to the brain include the insulin receptor (IR), the transferrin receptor (TfR), the insulin-like growth factor receptor (IGFR) and the leptin receptor. Therapeutic antibodies have been re-engineered as BSAs that target the insulin receptor, TfR, or IGFR RMT systems at the BBB for the treatment of Alzheimer's disease and Parkinson's disease.

Effect of HER2 expression status on the prognosis of patients with HR+/HER2‑ advanced breast cancer undergoing advanced first‑line endocrine therapy

The present study aimed to retrospectively assess the effects of human epidermal growth factor receptor 2 (HER2) expression on the diagnosis of patients with hormone receptor (HR)⁺/HER2^- late-stage breast cancer undergoing advanced first-line endocrine-based treatment. A total of 72 late-stage breast tumor cases from June 2017 to June 2019 were selected from the Department of Surgical Oncology, Shaanxi Provincial People's Hospital (Xi'an, China) and included in the present study. The expression of estrogen receptor, progesterone receptor and HER2 was detected by immunohistochemistry. The subjects were divided into two groups: the HER2-negative (0) cohort (n=31) and the HER2 low expression cohort (n=41). The age, BMI, Karnofsky Performance Status (KPS) score, tumor size, lymph node metastasis, pathological type, Ki-67 expression and menopausal status of the patients were obtained through the electronic medical record system of Shaanxi Provincial People's Hospital. Progression-free survival (PFS) and overall survival (OS) were evaluated for all patients. The median PFS and OS of the HER2(0) cohort were longer than those of the HER2 low expression cohort (all P<0.05). It was shown that age (hazard ratio, 6.000 and 5.465), KPS score (hazard ratio, 4.000 and 3.865), lymph node metastasis (hazard ratio, 3.143; 2.983) and HER2 status (hazard ratio, 3.167 and 2.996) were independent influencing factors of the prognosis of patients with HR⁺/HER2^- advanced breast cancer (ABC) (all P<0.05). Three models (model 1, no parameters adjusted; model 2, BMI, tumor size, pathological type, Ki-67 and menopausal status adjusted; and model 3, age, KPS functional status score and lymph node metastasis adjusted based on model 2) were established within the HER2(0) cohort as the reference for statistical analysis using the multivariate Cox's regression test. In models 2 and 3, the risk of poor prognosis of ABC within the HER2 low expression cohort was significantly higher compared with that in the HER2(0) cohort (hazard ratio, 3.558 and 4.477; 95% CI, 1.349-9.996 and 1.933-11.586; P=0.003 and P<0.001). The HER2 expression status of patients with HR⁺/HER2^- ABC receiving advanced first-line endocrine therapy may affect PFS and OS.

Breast cancer brain metastasis: from etiology to state-of-the-art modeling

Currently, breast carcinoma is the most common form of malignancy and the main cause of cancer mortality in women worldwide. The metastasis of cancer cells from the primary tumor site to other organs in the body, notably the lungs, bones, brain, and liver, is what causes breast cancer to ultimately be fatal. Brain metastases occur in as many as 30% of patients with advanced breast cancer, and the 1-year survival rate of these patients is around 20%. Many researchers have focused on brain metastasis, but due to its complexities, many aspects of this process are still relatively unclear. To develop and test novel therapies for this fatal condition, pre-clinical models are required that can mimic the biological processes involved in breast cancer brain metastasis (BCBM). The application of many breakthroughs in the area of tissue engineering has resulted in the development of scaffold or matrix-based culture methods that more accurately imitate the original extracellular matrix (ECM) of metastatic tumors. Furthermore, specific cell lines are now being used to create three-dimensional (3D) cultures that can be used to model metastasis. These 3D cultures satisfy the requirement for in vitro methodologies that allow for a more accurate investigation of the molecular pathways as well as a more in-depth examination of the effects of the medication being tested. In this review, we talk about the latest advances in modeling BCBM using cell lines, animals, and tissue engineering methods.

Real-world data of pyrotinib-based therapy for patients with brain metastases of HER2-positive advanced breast cancer: a single-center retrospective analysis and molecular portraits

Introduction

Pyrotinib is a novel irreversible pan-HER tyrosine kinase inhibitor (TKI). However, real-world data of pyrotinib-containing therapy in human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) and developing brain metastases (BMs) are limited, and the genomic profile of this subpopulation is almost undefined.

Methods and materials

Patients with BM of HER2-positive MBC (n = 35) treated with pyrotinib-containing therapy were enrolled in this analysis. Progression-free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR), and toxicity profiles were evaluated. Hazard ratios (HRs) and 95% confidence intervals (CIs) for disease progression were estimated using the Cox proportional hazards models. Targeted next-generation sequencing of 618 cancer-relevant genes was performed on plasma and primary breast tumors from patients with BM and without BM.

Results

The median PFS time was 8.00 (95% CI, 5.98-10.017) months, and the median OS time was 23 (95% CI, 10.412-35.588) months. The ORR was 45.7%, and the DCR was 74.3%. In the Cox multivariate analysis, prior exposure to brain radiotherapy (HR = 3.268), received pyrotinib as third- or higher-line treatment (HR = 4.949), subtentorial brain metastasis (HR = 6.222), and both supratentorial and subtentorial brain metastases (HR = 5.863) were independently associated with increased risk of progression. The frequent grade 3-4 adverse event was increased direct bilirubin (14.3%), and two patients suffered from grade 3-4 diarrhea. In the exploratory genomic analysis, altered frequencies of FGFR3, CD276, CDC73, and EPHX1 were higher in the BM group. The consistency of mutated profiles of plasma and primary lesion in the BM group was significantly lower (30.4% vs. 65.5%; p = 0.0038).

Conclusions

Pyrotinib-containing therapy shows favorable effectiveness and tolerable safety in patients with BM of HER2-positive MBC, particularly in a population that is brain radiotherapy-naïve, received pyrotinib as first- or second-line treatment, and developed supratentorial brain metastasis. In the exploratory genomic analysis, patients with BM showed distinct genomic features from patients without BM.

Genomic alterations of cerebrospinal fluid cell-free DNA in leptomeningeal metastases of gastric cancer

BACKGROUND

Leptomeningeal metastases (LM) were rare in gastric cancer (GC), and GC patients with LM (GCLM) generally suffer from poor prognosis. Nevertheless, the clinical utility of cerebrospinal fluid (CSF) circulating tumor DNA (ctDNA) was underinvestigated in GCLM.

METHODS

We retrospectively studied 15 GCLM patients, and all patients had paired primary tumor tissue samples and post-LM CSF samples while 5 patients also had post-LM plasma samples. All samples were analyzed using next-generation sequencing (NGS), and the molecular and clinical features were correlated with clinical outcomes.

RESULTS

CSF had higher mutation allele frequency (P = 0.015), more somatic mutations (P = 0.032), and more copy-number variations (P < 0.001) than tumor or plasma samples. Multiple genetic alterations and aberrant signal pathways were enriched in post-LM CSF, including CCNE1 amplification and cell cycle-related genes, and CCNE1 amplification was significantly associated with patients' overall survival (P = 0.0062). More potential LM progression-related markers were detected in CSF samples than in tumor samples, including PREX2 mutation (P = 0.014), IGF1R mutation (P = 0.034), AR mutation (P = 0.038), SMARCB1 deletion (P < 0.001), SMAD4 deletion (P = 0.0034), and TGF-beta pathway aberration (P = 0.0038). Additionally, improvement in intracranial pressure (P < 0.001), improvement in CSF cytology (P = 0.0038), and relatively low levels of CSF ctDNA (P = 0.0098) were significantly associated with better PFS. Lastly, we reported a GCLM case whose CSF ctDNA dynamic changes were well correlated with his clinical assessment.

CONCLUSIONS

CSF ctDNA could more sensitively detect molecular markers and metastasis-related mechanisms than tumor tissues in GCLM patients, and our study sheds light on utilizing CSF ctDNA in prognostic estimation and clinical assessment in GCLM.

Multi-Drug Resistance against Second-Line Medication and MicroRNA Plasma Level in Metastatic Breast Cancer Patients

Background

Circulating microRNAs (miRNAs) can help to predict the chemotherapy response in breast cancer with promising results. The aim of the present study was to investigate the relationships between the miR-199a, miR-663a, and miR-663b expression and chemotherapy response in metastatic breast cancer patients.

Methods

This study is a case-control study performed at Yasuj University of Medical Sciences (2018-2021). The expression levels of miR-663a, miR-663b, and miR-199a in the serum of 25 patients with metastatic breast cancer versus 15 healthy individuals were determined by the real-time polymerase chain reaction method. The response to treatment was followed up in a 24-month period. All patients were treated with second-line medications. Two or more combinations of these drugs were used: gemcitabine, Navelbine^®, Diphereline^®, Xeloda^®, letrozole, Aromasin^®, and Zolena^®. Statistical analyses were performed in SPSS 21.0 and GraphPad Prism 6 software. The expression levels were presented as mean±SD and analyzed by Student's t test.

Results

The results and clinicopathological features of patients were analyzed by t test. The statistical analysis showed that miR-663a expression was related to human epidermal growth factor receptor 2 (HER2) status and was significantly lower in the HER2⁺ than HER2^- group (P=0.027). Moreover, the expression of miR-199a and miR-663b was significantly correlated with the response to treatment, in which the expression of miR-199a was higher in the poor-response group (P=0.049), while the higher expression of miR-663b was seen in the good-response group (P=0.009).

Conclusion

These findings state that the high plasma level of miR-199a and the low plasma level of miR-663b may be related to chemoresistance in patients with metastatic breast cancer.

Association of lesion contour and lesion composition on MR with HER2 status in breast cancer brain metastases

BACKGROUND AND PURPOSE

With the development of HER2-directed therapies, identifying non-invasive imaging biomarkers of HER2 status in breast cancer brain metastases has become increasingly important, particularly given the risks of tissue sampling within the brain and the possibility of a change in receptor expression from the primary tumor to the brain metastasis. The purpose of this study was to evaluate whether lesion contour and composition on MR could help identify the HER2 status of breast cancer brain metastases.

MATERIALS AND METHODS

We derived a cohort of 34 women with a mean age of 55 years (range: 31-81 years) with a total of 47 distinct histologically proven breast cancer brain metastases with preoperative contrast-enhanced brain MR and HER2 immunohistochemistry and/or fluorescent in-situ hybridization (FISH) of the resected/biopsied brain specimens from 2018 to 2021. Two fellowship-trained neuroradiologists evaluated the lesion contour and lesion composition of each lesion. Logistic regression analyses were performed.

RESULTS

In a logistic regression model, an irregular contour had an odds ratio of 170 (p = 0.007) in differentiating HER2-positive from HER2-negative lesions. In a logistic regression model, when compared to a predominantly cystic lesion composition, a solid lesion composition had an odds ratio of 17 (p = 0.016) in differentiating HER2-positive from HER2-negative lesions.

CONCLUSION

Lesion contour and lesion composition on MR were significantly associated with the HER2 status of breast cancer brain metastases. Current assessment of HER2 status requires tissue sampling and immunochemical and/or FISH analyses. A non-invasive imaging biomarker that may help predict HER2 status may be of great clinical value.

Immune related biomarkers for cancer metastasis to the brain

Brain metastasis accounts for a large number of cancer-related deaths. The host immune system, involved at each step of the metastatic cascade, plays an important role in both the initiation of the brain metastasis and their treatment responses to various modalities, through either local and or systemic effect. However, few reliable immune biomarkers have been identified in predicting the development and the treatment outcome in patients with cancer brain metastasis. Here, we provide a focused perspective of immune related biomarkers for cancer metastasis to the brain and a thorough discussion of the potential utilization of specific biomarkers such as tumor mutation burden (TMB), genetic markers, circulating and tumor-infiltrating immune cells, cytokines, in predicting the brain disease progression and regression after therapeutic intervention. We hope to inspire the field to extend the research and establish practical guidelines for developing and validating immune related biomarkers to provide personalized treatment and improve treatment outcomes in patients with metastatic brain cancers.

HER2-Positive Gastroesophageal Cancers Are Associated with a Higher Risk of Brain Metastasis

Brain metastasis from gastroesophageal adenocarcinomas (GOCs) is a rare but a devastating diagnosis. Human epidermal growth factor receptor 2 (HER2) is a prognostic and predictive biomarker in GOCs. The association of HER2 with GOC brain metastasis is not known. We performed a retrospective analysis of patients with GOCs with known HER2 status between January 2015 and November 2021. HER2 was assessed on either the primary tumour or metastasis by immunohistochemistry or in situ hybridization. The diagnosis of brain metastasis was made on standard imaging techniques in patients with symptoms or signs. HER2 results were available for 201 patients, with 34 patients (16.9%) HER2 positive. A total of 12 patients developed symptomatic brain metastasis from GOCs, of which 7 (58.3%) were HER2 positive. The development of symptomatic brain metastasis was significantly higher in the HER2-positive GOCs (OR8.26, 95%CI 2.09-35.60; p = 0.0009). There was no significant association of HER2 status and overall survival in patients with brain metastasis. Although the rate of brain metastasis remains low in GOCs, the incidence of symptomatic brain metastasis was significantly higher in patients with HER2-positive tumours.

Innovative Approaches for Breast Cancer Metastasis to the Brain

Breast cancer metastasis is a continued concern for patients with recent development in our understanding of disease progression. In this paper, we highlight the pathophysiology behind breast cancer metastasis. Blood brain barrier disruption plays a critical component in progression. We then investigate the current treatment strategies and recommended guidelines. This focuses on radiation and medical management. Finally, we address the role of surgical intervention. The data is organized into tables and figures to highlight key components. Finally, we address emerging treatments and pre-clinical data. The paper will serve as a user-friendly guide for clinicians and researchers to help formulate a strategy to manage breast cancer metastasis patients sufficiently.

The efficacy of tucatinib-based therapeutic approaches for HER2-positive breast cancer

Overexpression of human epidermal growth factor receptor 2 (HER2) occurs in approximately 15-20% of breast cancer cases. HER2 is a member of the epidermal growth factor receptor (EGFR) family with tyrosinase kinase activity, and its overexpression is linked to poor prognosis and shorter progression-free survival (PFS) and overall survival (OS). Among various treatment options, HER2-targeting monoclonal antibodies and tyrosine kinase inhibitors (TKIs) have mostly been applied in recent decades to treat HER2-positive (HER2+) breast cancer patients. Although positive clinical outcomes were documented in both advanced disease and neoadjuvant settings, the development of resistance mechanisms to such approaches has been one of the major challenges with the continuous usage of these drugs. In addition, patients who experience disease progression after treatment with multiple HER2-targeted therapies often have limited treatment options. The Food and Drug Administration (FDA) has recently approved a new TKI (i.e., tucatinib) for use in combination with immunotherapy and/or chemotherapeutic agents for the treatment of advanced-stage/metastatic HER2+ breast cancer. This review highlights recent updates on the efficacy of tucatinib-based therapeutic approaches in experimental models as well as in the clinical settings of HER2+ breast cancer.

Fatty acid synthase: A druggable driver of breast cancer brain metastasis

INTRODUCTION

Brain metastasis (BrM) is a key contributor to morbidity and mortality in breast cancer patients, especially among high-risk epidermal growth factor receptor 2-positive (HER2+) and triple-negative/basal-like molecular subtypes. Optimal management of BrM is focused on characterizing a "BrM dependency map" to prioritize targetable therapeutic vulnerabilities.

AREAS COVERED

We review recent studies addressing the targeting of BrM in the lipid-deprived brain environment, which selects for brain-tropic breast cancer cells capable of cell-autonomously generating fatty acids by upregulating de novo lipogenesis via fatty acid synthase (FASN). Disruption of FASN activity impairs breast cancer growth in the brain, but not extracranially, and mapping of the molecular causes of organ-specific patterns of metastasis has uncovered an enrichment of lipid metabolism signatures in brain metastasizing cells. Targeting SREBP1-the master regulator of lipogenic gene transcription-curtails the ability of breast cancer cells to survive in the brain microenvironment.

EXPERT OPINION

Targeting FASN represents a new therapeutic opportunity for patients with breast cancer and BrM. Delivery of brain-permeable FASN inhibitors and identifying strategies to target metabolic plasticity that might compensate for impaired brain FASN activity are two potential roadblocks that may hinder FASN-centered strategies against BrM.

Nanotechnology in the development of small and large molecule tyrosine kinase inhibitors and immunotherapy for the treatment of HER2-positive breast cancer

The HER2 receptor tyrosine kinase is a member of the epidermal growth factor receptor family which includes EGFR, HER3 and HER4. They are known to play critical roles in both normal development and cancer. A subset of breast cancers is associated with the HER2 gene, which is amplified and/or overexpressed in 20-25% of invasive breast cancers and is correlated with tumor resistance to chemotherapy, Metastatic Breast Cancer (MBC) and poor patient survival. The advent of receptor tyrosine kinase inhibitors has improved the prognosis of HER2-postive breast cancers; however, HER2+MBC invariably progresses (acquired resistance or de novo resistance). The monoclonal antibody-based drugs (large molecule TKIs) target the extracellular binding domain of HER2; while the small molecule TKIs act intracellularly to inhibit proliferation and survival signals. We reviewed the modes of action of the TKIs with a view to showing which of the TKIs could be combined in nanoparticles to benefit from the power of nanotechnology (reduced toxicity, improved solubility of hydrophobic drugs, long circulation half-lives, circumventing efflux pumps and preventing capture by the reticuloendothelial system (mononuclear phagocyte system). Nanotherapeutics also mediate the synchronization of the pharmacokinetics and biodistribution of multiple drugs incorporated in the nanoparticles. Novel TKIs that are currently under investigation with or without nanoparticle delivery are mentioned, and nano-based strategies to improve their delivery are suggested. Immunotherapies currently in clinical practice, clinical trials or at the preclinical stage are discussed. However, immunotherapy only works well in relatively small subsets of patients. Combining nanomedicine with immunotherapy can boost therapeutic outcomes, by turning "cold" non-immunoresponsive tumors and metastases into "hot" immunoresponsive lesions.

A Need for More Molecular Profiling in Brain Metastases

As local disease control improves, the public health impact of brain metastases (BrM) continues to grow. Molecular features are frequently different between primary and metastatic tumors as a result of clonal evolution during neoplasm migration, selective pressures imposed by systemic treatments, and differences in the local microenvironment. However, biomarker information in BrM is not routinely obtained despite emerging evidence of its clinical value. We review evidence of discordance in clinically actionable biomarkers between primary tumors, extracranial metastases, and BrM. Although BrM biopsy/resection imposes clinical risks, these risks must be weighed against the potential benefits of assessing biomarkers in BrM. First, new treatment targets unique to a patient's BrM may be identified. Second, as BrM may occur late in a patient's disease course, resistance to initial targeted therapies and/or loss of previously identified biomarkers can occur by the time of occult BrM, rendering initial and other targeted therapies ineffective. Thus, current biomarker data can inform real-time treatment options. Third, biomarker information in BrM may provide useful prognostic information for patients. Appreciating the importance of biomarker analyses in BrM tissue, including how it may identify specific drivers of BrM, is critical for the development of more effective treatment strategies to improve outcomes for this growing patient population.

Combination of tucatinib and neural stem cells secreting anti-HER2 antibody prolongs survival of mice with metastatic brain cancer

Brain metastases are among the most severe complications of systemic breast cancer, and overexpression of the human epidermal growth factor receptor 2 (HER2) in breast cancer cells increases the incidence of brain metastases in patients. In this study, we engineered the human-derived, tumor cell tropic neural stem cells LM-NSC008 (LM008) to continuously secrete antibodies against HER2. These anti-HER2 antibodies impaired tumor cell proliferation by inhibiting the PI3K-Akt signaling pathway in HER2+ breast cancer cells in vitro. Importantly, our results demonstrate that the therapeutic combinatorial regimen consisting of LM-NSC008 anti-HER2 antibody-secreting cells and the HER2 kinase inhibitor tucatinib provide therapeutic benefit and prolong survival in preclinical models of HER2+ breast cancer brain metastases.

Brain metastases are a leading cause of death in patients with breast cancer. The lack of clinical trials and the presence of the blood–brain barrier limit therapeutic options. Furthermore, overexpression of the human epidermal growth factor receptor 2 (HER2) increases the incidence of breast cancer brain metastases (BCBM). HER2-targeting agents, such as the monoclonal antibodies trastuzumab and pertuzumab, improved outcomes in patients with breast cancer and extracranial metastases. However, continued BCBM progression in breast cancer patients highlighted the need for novel and effective targeted therapies against intracranial metastases. In this study, we engineered the highly migratory and brain tumor tropic human neural stem cells (NSCs) LM008 to continuously secrete high amounts of functional, stable, full-length antibodies against HER2 (anti-HER2Ab) without compromising the stemness of LM008 cells. The secreted anti-HER2Ab impaired tumor cell proliferation in vitro in HER2+ BCBM cells by inhibiting the PI3K-Akt signaling pathway and resulted in a significant benefit when injected in intracranial xenograft models. In addition, dual HER2 blockade using anti-HER2Ab LM008 NSCs and the tyrosine kinase inhibitor tucatinib significantly improved the survival of mice in a clinically relevant model of multiple HER2+ BCBM. These findings provide compelling evidence for the use of HER2Ab-secreting LM008 NSCs in combination with tucatinib as a promising therapeutic regimen for patients with HER2+ BCBM.

From blood to brain: blood cell-based biomimetic drug delivery systems

Brain drug delivery remains a major difficulty for several challenges including the blood-brain barrier, lesion spot targeting, and stability during circulation. Blood cells including erythrocytes, platelets, and various subpopulations of leukocytes have distinct features such as long-circulation, natural targeting, and chemotaxis. The development of biomimetic drug delivery systems based on blood cells for brain drug delivery is growing fast by using living cells, membrane coating nanotechnology, or cell membrane-derived nanovesicles. Blood cell-based vehicles are superior delivery systems for their engineering feasibility and versatile delivery ability of chemicals, proteins, and all kinds of nanoparticles. Here, we focus on advances of blood cell-based biomimetic carriers for from blood to brain drug delivery and discuss their translational challenges in the future.

HER2-low breast cancer could be associated with an increased risk of brain metastasis

PURPOSE

The HER2-low breast cancer is a newly recognized entity with the clinical characteristics is yet to be defined. We hypothesized that HER2-low breast cancer could lead to an increased rate of brain metastases in patients with localized breast cancer. We tested this hypothesis in a large cohort of breast cancer patients with long follow-up.

METHODS

We included 2686 adult breast cancer patients followed up in Hacettepe University Cancer Center. Patients with 1 + positive HER2 expression and 2 + HER2 expression with a negative FISH were categorized as HER2-low disease. We evaluated the brain metastasis risk with binary logistic regression analyses and reported odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

During a median 95.4 (IQR 72.6-123.1) month follow-up, 184 patients developed brain metastasis (6.9%). The brain metastases were developed in 5.1% of the patients with HER2-negative disease, 8.5% of the patients with HER2-low disease, and 10.1% of the patients with HER2-positive disease. A multivariable binary logistic regression model demonstrated an increased risk of brain metastasis in patients with HER2-low disease (OR: 1.611, 95% CI 1.055-2.460, p = 0.027) and in HER2-positive patients (OR: 1.837, 95% CI 1.308-2.580, p < 0.001). Additionally, HR + -HER2-low disease was associated with a decreased DFS compared to HR + -HER2-negative disease (p = 0.008).

CONCLUSION

In this study, we observed an increased risk of brain metastasis in localized breast cancer patients with HER2-low disease. We think that a high level of vigilance and a low threshold for brain imaging could benefit HER2-low breast cancer patients similar to the patients with HER-positive disease.

Human induced pluripotent stem cell-derived platelets loaded with lapatinib effectively target HER2+ breast cancer metastasis to the brain

Prognosis of patients with HER2+ breast-to-brain-metastasis (BBM) is dismal even after current standard-of-care treatments, including surgical resection, whole-brain radiation, and systemic chemotherapy. Radiation and systemic chemotherapies can also induce cytotoxicity, leading to significant side effects. Studies indicate that donor-derived platelets can serve as immune-compatible drug carriers that interact with and deliver drugs to cancer cells with fewer side effects, making them a promising therapeutic option with enhanced antitumor activity. Moreover, human induced pluripotent stem cells (hiPSCs) provide a potentially renewable source of clinical-grade transfusable platelets that can be drug-loaded to complement the supply of donor-derived platelets. Here, we describe methods for ex vivo generation of megakaryocytes (MKs) and functional platelets from hiPSCs (hiPSC-platelets) in a scalable fashion. We then loaded hiPSC-platelets with lapatinib and infused them into BBM tumor-bearing NOD/SCID mouse models. Such treatment significantly increased intracellular lapatinib accumulation in BBMs in vivo, potentially via tumor cell-induced activation/aggregation. Lapatinib-loaded hiPSC-platelets exhibited normal morphology and function and released lapatinib pH-dependently. Importantly, lapatinib delivery to BBM cells via hiPSC-platelets inhibited tumor growth and prolonged survival of tumor-bearing mice. Overall, use of lapatinib-loaded hiPSC-platelets effectively reduced adverse effects of free lapatinib and enhanced its therapeutic efficacy, suggesting that they represent a novel means to deliver chemotherapeutic drugs as treatment for BBM.

Performance of enhancement on brain MRI for identifying HER2 overexpression in breast cancer brain metastases

PURPOSE

To investigate whether enhancement on MRI could help identify HER2 overexpression in breast cancer brain metastases.

METHODS

We derived a cohort of 38 histologically proven breast cancer brain metastases with preoperative contrast-enhanced brain MRI and HER2 fluorescent in-situ hybridization of the resected/biopsied brain specimens from 2018 to 2021. Enhancement of the lesions was measured and compared using t-tests. Receiver operating characteristic and logistic regression analyses were performed to evaluate the performance of MRI enhancement in identifying HER2 overexpression.

RESULTS

The study cohort was comprised of 29 women with a mean age of 55 years (range: 31-81 years) with a total of 38 distinct lesions. The HER2-positive subcohort was comprised of 17 patients, while the HER2-negative subcohort was comprised of 13 patients. The percent signal intensity change (PSIC) of HER2-positive breast cancer brain metastases was significantly greater than that of HER2-negative lesions (310 v. 153, P = 0.002). The PSIC differentiated HER2-positive lesions from HER2-negative lesions with an area under the curve of 0.88 (P < 0.001). In a model controlling for lesion size, lesion location, tumor grade, patient age, scanner magnetic field strength, and contrast agent, the PSIC had an accuracy of 92% (35/38), sensitivity of 96% (23/24), and specificity of 86% (12/14) in differentiating HER2-positive lesions from HER2-negative lesions.

CONCLUSION

Enhancement on MRI may assist in identifying HER2 overexpression in breast cancer brain metastases, if validated prospectively.

Labeling single domain antibody fragments with 18F using a novel residualizing prosthetic agent - N-succinimidyl 3-(1-(2-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-5-(guanidinomethyl)benzoate

INTRODUCTION

Labeling single domain antibody fragments (sdAbs) with 18F is an attractive strategy for immunoPET. Earlier, we developed a residualizing label, N-succinimidyl 3-((4-(4-fluorobutyl)-1H-1,2,3-triazol-1-yl)methyl)-5-(guanidinomethyl)benzoate ([18F]RL-I), synthesized via a click reaction for labeling sdAbs with 18F, that has attractive features but suffered from modest radiochemical yields and suboptimal hydrophobicity. Herein, we have evaluated the potential utility of an analogous agent, N-succinimidyl 3-(1-(2-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-5-(guanidinomethyl)benzoate ([18F]SFETGMB; [18F]RL-III) designed to address these limitations.

METHODS

[18F]RL-III was synthesized by the click reaction between 3-((2,3-bis(tert-butoxycarbonyl)guanidino)methyl)-5-ethynylbenzoate and 1-azido-2-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)ethane and subsequent deprotection. The anti-HER2 sdAbs 5F7 and 2Rs15d were labeled by conjugation with [18F]RL-III and compared in a paired-label fashion to the sdAbs labeled using N-succinimidyl 4-guanidinomethyl-3-[125I]iodobenzoate ([125I]SGMIB) or N-succinimidyl 3-guanidinomethyl-5-[125I]iodobenzoate (iso-[125I]SGMIB). The 18F-labeled sdAbs were evaluated in vitro using HER2-expressing breast and ovarian carcinoma cells (BT474/BT474M1 and SKOV-3) and in vivo in athymic mice bearing subcutaneous SKOV-3 or BT474 xenografts. PET imaging of athymic mice bearing either subcutaneous BT474 or intracranial BT474M1Br-Fluc xenografts after administration of [18F]RL-III-5F7 also was performed.

RESULTS

Radiochemical yields for the synthesis of Boc2-[18F]RL-III (21.5 ± 3.4%) were significantly higher than reported for Boc2-[18F]RL-I. The overall radiochemical yields for the synthesis of [18F]RL-III-2Rs15d and [18F]RL-III-5F7 from aqueous [18F]fluoride were 1.7 ± 0.7% and 3.8 ± 2.3%, respectively. Both sdAbs, labeled using [18F]RL-III, retained affinity and immunoreactivity to HER2. Uptake and internalization of [18F]RL-III-5F7 in HER2-expressing cells was higher than that seen for [18F]RL-III-2Rs15d. Although different xenograft models were used, [18F]RL-III-2Rs15d showed relatively high uptake in a number of normal tissues, while uptake of [18F]RL-III-5F7 was mainly in tumor and kidneys with minimal background activity. Concordant with the necropsy experiments, microPET imaging with [18F]RL-III-5F7 in the BT474 subcutaneous model demonstrated clear delineation of the tumor (12.2 ± 5.1% ID/g) with minimal background activity except in kidneys. A tumor uptake (max) of 0.98%ID/g and a tumor-to-normal brain ratio of 9.8:1 were observed for [18F]RL-III-5F7 in the intracranial model.

CONCLUSIONS

Although higher radiochemical yields than that reported for [18F]RL-I were obtained, considerable improvements are needed for this method to be of practical utility. Despite clear tumor delineation with [18F]RL-III-5F7 as early as 1 h, high activity levels in the kidneys remain a concern.

Trastuzumab deruxtecan in HER2-positive metastatic breast cancer and beyond

INTRODUCTION

Despite the substantial improvements made in human epidermal growth factor receptor 2 (HER2)-targeted therapies since the approval of trastuzumab more than 20 years ago, there is still considerable unmet need in patients with HER2-expressing breast cancer (BC) and other solid tumors. Trastuzumab deruxtecan (T-DXd) is a newer antibody-drug conjugate approved for the treatment of metastatic breast cancer (BC) and gastric cancer (GC) and is under active investigation in other solid tumors, including non-small cell lung cancer, colorectal cancer, and HER2-low tumors.

AREAS COVERED

The current treatment and investigational landscape of HER2-positive and HER2-low metastatic BC (mBC) and the preclinical and clinical trials investigating T-DXd. To identify relevant literature, a search was performed on English-language publications and congress abstracts.

EXPERT OPINION

T-DXd is likely to become the standard of care for second-line treatment of HER2-positive mBC, and it may play a role in the treatment of hormone receptor-positive and triple-negative mBC with HER2-low expression. Because it was recently approved in the United States and Japan to treat HER2-positive metastatic GC, it holds promise for the treatment of other HER2-positive solid tumors, including colorectal cancer, non-small cell lung cancer, and HER2-low BC.

Breast cancer subtype predicts clinical outcomes after stereotactic radiation for brain metastases

PURPOSE

We investigated the prognostic ability of tumor subtype for patients with breast cancer brain metastases (BCBM) treated with stereotactic radiation (SRT).

METHODS

This is a retrospective review of 181 patients who underwent SRT to 664 BCBM from 2004 to 2019. Patients were stratified by subtype: hormone receptor (HR)-positive, HER2-negative (HR+/HER2-), HR-positive, HER2-positive (HR+/HER2+), HR-negative, HER2-positive (HR-/HER2+), and triple negative (TN). The Kaplan-Meier method was used to calculate overall survival (OS), local control (LC), and distant intracranial control (DIC) from the date of SRT. Multivariate analysis (MVA) was conducted using the Cox proportional hazards model.

RESULTS

Median follow up from SRT was 11.4 months. Of the 181 patients, 47 (26%) were HR+/HER2+, 30 (17%) were HR-/HER2+, 60 (33%) were HR+/HER2-, and 44 (24%) were TN. Of the 664 BCBMs, 534 (80%) received single fraction stereotactic radiosurgery (SRS) with a median dose of 21 Gy (range 12-24 Gy), and 130 (20%) received fractionated stereotactic radiation therapy (FSRT), with a median dose of 25 Gy (range 12.5-35 Gy) delivered in 3 to 5 fractions. One-year LC was 90%. Two-year DIC was 35%, 23%, 27%, and 16% (log rank, p = 0.0003) and 2-year OS was 54%, 47%, 24%, and 12% (log rank, p < 0.0001) for HR+/HER2+, HR-/HER2+, HR+/HER2-, and TN subtypes, respectively. On MVA, the TN subtype predicted for inferior DIC (HR 1.62, 95% CI 1.00-2.60, p = 0.049). The modified breast-Graded Prognostic Assessment (GPA) significantly predicted DIC and OS (both p < 0.001).

CONCLUSIONS

Subtype is prognostic for OS and DIC for patients with BCBM treated with SRT.

Dual- versus single-agent HER2 inhibition and incidence of intracranial metastatic disease: a systematic review and meta-analysis

Observational studies have suggested that HER2 inhibition with trastuzumab may be associated with an increased incidence of intracranial metastatic disease (IMD) due to its ability to prolong survival. We hypothesized that prolonged survival associated with dual-agent HER2 inhibition may be associated with an even higher incidence of IMD. This study pooled estimates of IMD incidence and survival among patients with HER2-positive breast cancer receiving dual- versus single-agent HER2 targeted therapy, as well as trastuzumab versus chemotherapy, observation, or another HER2-targeted agent. We searched PubMed, EMBASE, and CENTRAL from inception to 25 March 2020. We included randomized controlled trials that reported IMD incidence for patients with HER2-positive breast cancer receiving trastuzumab as the experimental or control arm irrespective of disease stage. Among 465 records identified, 19 randomized controlled trials (32,572 patients) were included. Meta-analysis of four studies showed that dual HER2-targeted therapy was associated with improved overall survival (HR 0.76; 95% CI, 0.66–0.87) and progression-free survival (HR 0.77; 95% CI, 0.68–0.87) compared to single HER2-targeted therapy, but the risk of IMD was similar (RR 1.03; 95% CI, 0.83–1.27). Our study challenges the hypothesis that prolonged survival afforded by improved extracranial disease control is associated with increased IMD incidence.

The miR-1185-2-3p-GOLPH3L pathway promotes glucose metabolism in breast cancer by stabilizing p53-induced SERPINE1

Background

Phosphatidylinositol-4-phosphate-binding protein GOLPH3L is overexpressed in human ductal carcinoma of the breast, and its expression levels correlate with the prognosis of breast cancer patients. However, the roles of GOLPH3L in breast tumorigenesis remain unclear.

Methods

We assessed the expression and biological function of GOLPH3L in breast cancer by combining bioinformatic prediction, metabolomics analysis and RNA-seq to determine the GOLPH3L-related pathways involved in tumorigenesis. Dual-luciferase reporter assay and coimmunoprecipitation (Co-IP) were used to explore the expression regulation mechanism of GOLPH3L.

Results

We demonstrated that knockdown of GOLPH3L in human breast cancer cells significantly suppressed their proliferation, survival, and migration and suppressed tumor growth in vivo, while overexpression of GOLPH3L promoted aggressive tumorigenic activities. We found that miRNA-1185-2-3p, the expression of which is decreased in human breast cancers and is inversely correlated with the prognosis of breast cancer patients, is directly involved in suppressing the expression of GOLPH3L. Metabolomics microarray analysis and transcriptome sequencing analysis revealed that GOLPH3L promotes central carbon metabolism in breast cancer by stabilizing the p53 suppressor SERPINE1.

Conclusions

In summary, we discovered a miRNA-GOLPH3L-SERPINE1 pathway that plays important roles in the metabolism of breast cancer and provides new therapeutic targets for human breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01767-9.

"Triple-Negative Breast Cancer Central Nervous System Metastases From the Laboratory to the Clinic"

ABSTRACT

Triple-negative breast cancer (TNBC) accounts for 15% to 20% of breast cancers and has an incidence as high as 50% of brain metastases once patients develop advanced disease. The lack of targeted and effective therapies, characteristic of this subtype of breast cancer, is especially evident once central nervous system (CNS) metastases occur. Compared with other subtypes of breast cancer, TNBC patients have the shorter interval from diagnosis to development of brain metastases and the shorter overall survival once they occur, a median of 4 to 6 months. Preclinical studies of TNBC and CNS microenvironment are actively ongoing, clarifying mechanisms and orienting more effective approaches to therapy. While the first drugs have been specifically approved for use in metastatic TNBC, data on their CNS effect are still awaited.