Phase II study of intrathecal administration of trastuzumab in patients with HER2-positive breast cancer with leptomeningeal metastasis

Leptomeningeal metastases from solid tumors: A Society for Neuro-Oncology and American Society of Clinical Oncology consensus review on clinical management and future directions

Leptomeningeal metastases (LM) are increasingly becoming recognized as a treatable, yet generally incurable, complication of advanced cancer. As modern cancer therapeutics have prolonged the lives of patients with metastatic cancer, specifically in patients with parenchymal brain metastases, treatment options, and clinical research protocols for patients with LM from solid tumors have similarly evolved to improve survival within specific populations. Recent expansions in clinical investigation, early diagnosis, and drug development have given rise to new unanswered questions. These include leptomeningeal metastasis biology and preferred animal modeling, epidemiology in the modern cancer population, ensuring validation and accessibility of newer leptomeningeal metastasis diagnostics, best clinical practices with multimodality treatment options, clinical trial design and standardization of response assessments, and avenues worthy of further research. An international group of multi-disciplinary experts in the research and management of LM, supported by the Society for Neuro-Oncology and American Society of Clinical Oncology, were assembled to reach a consensus opinion on these pressing topics and provide a roadmap for future directions. Our hope is that these recommendations will accelerate collaboration and progress in the field of LM and serve as a platform for further discussion and patient advocacy.

A comprehensive review of current treatment modalities for leptomeningeal carcinomatosis in breast cancer

Leptomeningeal carcinomatosis (LC) is a metastatic complication of breast cancer that imparts a very poor prognosis and distressing neurologic symptoms in affected patients. While the incidence of LC has risen with improving survival rates for cancer patients, there remains no established treatment protocol for LC and clinical trial data comparing available therapies is limited. Here, a comprehensive literature search of the pubmed and Cochrane databases was performed. Current treatment modalities and their safety/ efficacy profiles are summarized for LC in breast cancer. Roles for emerging therapies in LC are discussed, including targeted agents, CAR-T, immune checkpoint inhibitors, CDK inhibitors and novel antibody conjugates. A treatment pathway for LC is also proposed to guide clinicians through management of this severe metastatic complication of breast cancer.

6th and 7th International consensus guidelines for the management of advanced breast cancer (ABC guidelines 6 and 7)

This manuscript describes the Advanced Breast Cancer (ABC) international consensus guidelines updated at the last two ABC international consensus conferences (ABC 6 in 2021, virtual, and ABC 7 in 2023, in Lisbon, Portugal), organized by the ABC Global Alliance. It provides the main recommendations on how to best manage patients with advanced breast cancer (inoperable locally advanced or metastatic), of all breast cancer subtypes, as well as palliative and supportive care. These guidelines are based on available evidence or on expert opinion when a higher level of evidence is lacking. Each guideline is accompanied by the level of evidence (LoE), grade of recommendation (GoR) and percentage of consensus reached at the consensus conferences. Updated diagnostic and treatment algorithms are also provided. The guidelines represent the best management options for patients living with ABC globally, assuming accessibility to all available therapies. Their adaptation (i.e. resource-stratified guidelines) is often needed in settings where access to care is limited.

The path to leptomeningeal metastasis

The leptomeninges, the cerebrospinal-fluid-filled tissues surrounding the central nervous system, play host to various pathologies including infection, neuroinflammation and malignancy. Spread of systemic cancer into this space, termed leptomeningeal metastasis, occurs in 5-10% of patients with solid tumours and portends a bleak clinical prognosis. Previous, predominantly descriptive, clinical studies have provided few insights. Recent development of preclinical leptomeningeal metastasis models, alongside genomic, transcriptomic and proteomic sequencing efforts, has provided groundwork for mechanistic understanding and identification of long-needed therapeutic targets. Although previously understood as an anatomically isolated compartment, the leptomeninges are increasingly appreciated as a major conduit of communication between the systemic circulation and the central nervous system. Despite the unique nature of the leptomeningeal microenvironment, the general principles of metastasis hold true: cells metastasizing to the leptomeninges must gain access to the new environment, survive within the space and evade the immune system. The study of leptomeningeal metastasis has the potential to uncover novel site-specific metastatic principles and illuminate the physiology of the leptomeningeal space. In this Review, we provide a biology-focused overview of how metastatic cells reach the leptomeninges, thrive in this nutritionally sparse environment and evade the detection of the omnipresent immune system.

Prognostic impact of clinical and radiological factors on leptomeningeal metastasis from solid cancers

PURPOSE

The number of leptomeningeal metastasis (LM) patients has increased in recent years, as the cancer survival rates increased. An optimal prediction of prognosis is essential for selecting an appropriate treatment. The European Association of Neuro-Oncology-European Society for Medical Oncology (EANO-ESMO) guidelines for LM proposed a classification based on the cerebrospinal fluid cytological findings and contrast-enhanced magnetic resonance imaging (MRI) pattern. However, few studies have validated the utility of this classification. This study aimed to investigate the prognostic factors of LM, including the radiological and cytological types.

METHODS

We retrospectively analyzed the data of 240 adult patients with suspected LM who had undergone lumbar puncture between April 2014 and September 2021.

RESULTS

The most common primary cancer types were non-small-cell lung cancer (NSCLC) (143 (60%)) and breast cancer (27 (11%)). Positive cytology results and the presence of leptomeningeal lesions on contrast-enhanced MRI correlated with decreased survival in all patients. Nodular lesions detected on contrast-enhanced magnetic resonance were a poor prognostic factor in cytology-negative patients, while contrast-enhanced patterns had no prognostic significance in cytology-positive patients. Systemic therapy using cytotoxic agents and molecular-targeted therapy after LM diagnosis correlated with prolonged survival, regardless of the cytology results. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor treatment and systemic chemotherapy after LM improved the survival of EGFR-mutated and wild-type NSCLC patients with positive cytology results.

CONCLUSIONS

This study validated the efficacy of prognostication according to the EANO-ESMO guidelines for LM. Systemic therapy after LM diagnosis improves the survival of NSCLC patients.

Mechanistic Modeling of Intrathecal Chemotherapy Pharmacokinetics in the Human Central Nervous System

PURPOSE

The pharmacokinetics of intrathecally administered antibody or small-molecule drugs in the human central nervous system (CNS) remains poorly understood. This study aimed to provide mechanistic and quantitative perspectives on the CNS pharmacokinetics of intrathecal chemotherapy, by using a physiologically based pharmacokinetic (PBPK) modeling approach.

EXPERIMENTAL DESIGN

A novel CNS PBPK model platform was developed and verified, which accounted for the human CNS general anatomy and physiologic processes governing drug distribution and disposition. The model was used to predict CNS pharmacokinetics of antibody (trastuzumab) and small-molecule drugs (methotrexate, abemaciclib, tucatinib) following intraventricular injection or intraventricular 24-hour infusion, and to assess the key determinants of drug penetration into the deep brain parenchyma.

RESULTS

Intraventricularly administered antibody and small-molecule drugs exhibited distinct temporal and spatial distribution and disposition in human CNS. Both antibody and small-molecule drugs achieved supratherapeutic or therapeutic concentrations in the cerebrospinal fluid (CSF) compartments and adjacent brain tissue. While intrathecal small-molecule drugs penetrated the deep brain parenchyma to a negligible extent, intrathecal antibodies may achieve therapeutic concentrations in the deep brain parenchyma. Intraventricular 24-hour infusion enabled prolonged CNS exposure to therapeutically relevant concentrations while avoiding excessively high and potentially neurotoxic drug concentrations.

CONCLUSIONS

CNS PBPK modeling, in line with available clinical efficacy data, confirms the therapeutic value of intrathecal chemotherapy with antibody or small-molecule drugs for treating neoplastic meningitis and warrants further clinical investigation of intrathecal antibody drugs to treat brain parenchyma tumors. Compared with intraventricular injection, intraventricular 24-hour infusion may mitigate neurotoxicity while retaining potential efficacy.

DEGRO guideline for personalized radiotherapy of brain metastases and leptomeningeal carcinomatosis in patients with breast cancer

PURPOSE

The aim of this review was to evaluate the existing evidence for radiotherapy for brain metastases in breast cancer patients and provide recommendations for the use of radiotherapy for brain metastases and leptomeningeal carcinomatosis.

MATERIALS AND METHODS

For the current review, a PubMed search was conducted including articles from 01/1985 to 05/2023. The search was performed using the following terms: (brain metastases OR leptomeningeal carcinomatosis) AND (breast cancer OR breast) AND (radiotherapy OR ablative radiotherapy OR radiosurgery OR stereotactic OR radiation).

CONCLUSION AND RECOMMENDATIONS

Despite the fact that the biological subtype of breast cancer influences both the occurrence and relapse patterns of breast cancer brain metastases (BCBM), for most scenarios, no specific recommendations regarding radiotherapy can be made based on the existing evidence. For a limited number of BCBM (1-4), stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SRT) is generally recommended irrespective of molecular subtype and concurrent/planned systemic therapy. In patients with 5-10 oligo-brain metastases, these techniques can also be conditionally recommended. For multiple, especially symptomatic BCBM, whole-brain radiotherapy (WBRT), if possible with hippocampal sparing, is recommended. In cases of multiple asymptomatic BCBM (≥ 5), if SRS/SRT is not feasible or in disseminated brain metastases (> 10), postponing WBRT with early reassessment and reevaluation of local treatment options (8-12 weeks) may be discussed if a HER2/Neu-targeting systemic therapy with significant response rates in the central nervous system (CNS) is being used. In symptomatic leptomeningeal carcinomatosis, local radiotherapy (WBRT or local spinal irradiation) should be performed in addition to systemic therapy. In patients with disseminated leptomeningeal carcinomatosis in good clinical condition and with only limited or stable extra-CNS disease, craniospinal irradiation (CSI) may be considered. Data regarding the toxicity of combining systemic therapies with cranial and spinal radiotherapy are sparse. Therefore, no clear recommendations can be given, and each case should be discussed individually in an interdisciplinary setting.

Intrathecal Trastuzumab for HER2-Positive Cancer of Unknown Primary Leptomeningeal Metastasis: A Case Report

Cancer of unknown primary (CUP) and leptomeningeal metastasis are difficult conditions with limited treatment options. We report a case of CUP leptomeningeal metastasis that was refractory to empirical chemotherapy but achieved a favorable response to intrathecal trastuzumab after the identification of human epidermal growth factor receptor-2 (HER2) amplification. A 59-year-old woman was diagnosed with CUP with metastasis of a poorly differentiated carcinoma to the left axillary, anterior mediastinal, peritoneal, and bilateral supraclavicular lymph nodes. Leptomeningeal metastasis was confirmed shortly after she started empiric chemotherapy; empiric therapy with intrathecal methotrexate failed to relieve her symptoms. Meanwhile, the lymph node specimen tested positive for HER2 amplification. She underwent intrathecal trastuzumab, then her neurological symptoms resolved the following day. We suggest that intrathecal trastuzumab is an effective treatment for HER2-positive CUP leptomeningeal metastasis.

Long-term response to sequential anti-HER2 therapies including trastuzumab-deruxtecan in a patient with HER2-positive metastatic breast cancer with leptomeningeal metastases: a case report and review of the literature

The incidence of leptomeningeal metastases (LM) is increasing among breast cancer patients, but their prognosis remains dismal. Many therapeutic options are now available to treat HER2-positive (HER2+) metastatic breast cancer (MBC) involving the central nervous system (CNS). This case report illustrates a long-lasting response of more than 2 years in a patient with HER2+ MBC with LM after sequential administration of systemic and intrathecal (IT) anti-HER2 therapies and highlights that an appropriate treatment of HER2+ LM can result in durable survival.

Breaking Barriers in Neuro-Oncology: A Scoping Literature Review on Invasive and Non-Invasive Techniques for Blood-Brain Barrier Disruption

The blood-brain barrier (BBB) poses a significant challenge to drug delivery for brain tumors, with most chemotherapeutics having limited permeability into non-malignant brain tissue and only restricted access to primary and metastatic brain cancers. Consequently, due to the drug's inability to effectively penetrate the BBB, outcomes following brain chemotherapy continue to be suboptimal. Several methods to open the BBB and obtain higher drug concentrations in tumors have been proposed, with the selection of the optimal method depending on the size of the targeted tumor volume, the chosen therapeutic agent, and individual patient characteristics. Herein, we aim to comprehensively describe osmotic disruption with intra-arterial drug administration, intrathecal/intraventricular administration, laser interstitial thermal therapy, convection-enhanced delivery, and ultrasound methods, including high-intensity focused and low-intensity ultrasound as well as tumor-treating fields. We explain the scientific concept behind each method, preclinical/clinical research, advantages and disadvantages, indications, and potential avenues for improvement. Given that each method has its limitations, it is unlikely that the future of BBB disruption will rely on a single method but rather on a synergistic effect of a combined approach. Disruption of the BBB with osmotic infusion or high-intensity focused ultrasound, followed by the intra-arterial delivery of drugs, is a promising approach. Real-time monitoring of drug delivery will be necessary for optimal results.

Pharmacotherapy for leptomeningeal disease in breast cancer

Clinical data supporting the best therapeutic approach in leptomeningeal disease (LMD; also known as leptomeningeal metastases or leptomeningeal carcinomatosis) are lacking. Despite the development of new agents and increasing incidence of central nervous system metastases, patients with LMD are often excluded from clinical trials in breast cancer, with very few conducted specifically in LMD. Consequently, current evidence may not provide an accurate reflection of real-world clinical practice. This review aims to provide further insight into the treatment strategies for patients with breast cancer and LMD. We explore differences between clinical and real-world studies, considering inclusion criteria, levels of evidence for LMD diagnosis, and time between diagnosis of LMD and LMD-specific treatment initiation. Patient prognosis is poor; median overall survival is limited to several months, with approximately 10% of patients alive at 12 months. Efficacy results have been reported for various systemic and intrathecal agents in LMD to date. Systemic therapies under investigation for LMD in breast cancer include tucatinib, trastuzumab deruxtecan, and paclitaxel trevatide; trastuzumab is the main intrathecal agent currently under investigation. Recent trials investigating systemic or intrathecal therapies are typically small, single-arm studies, and most are restricted to patients with human epidermal growth factor receptor 2-positive breast cancer. Moreover, the variability among inclusion criteria and response assessment tools makes the interpretation of results difficult. Large retrospective cohorts with various inclusion criteria and treatment regimens provide some real-world data. However, there remains an urgent need for randomised clinical trials which include patients with LMD across all breast cancer subtypes.

An overview of the therapeutic strategies for neoplastic meningitis due to breast cancer: when and why?

INTRODUCTION

Neoplastic meningitis (NM), also known as leptomeningeal carcinomatosis, is characterized by the infiltration of tumor cells into the meninges, and poses a significant therapeutic challenge owing to its aggressive nature and limited treatment options. Breast cancer is a common cause of NM among solid tumors, further highlighting the urgent need to explore effective therapeutic strategies. This review aims to provide insights into the evolving landscape of NM therapy in breast cancer by collating existing research, evaluating current treatments, and identifying potential emerging therapeutic options.

AREAS COVERED

This review explores the clinical features, therapeutic strategies, recent advances, and challenges of managing NM in patients with breast cancer. Its management includes multimodal strategies, including systemic and intrathecal chemotherapy, radiation therapy, and supportive care. This review also emphasizes targeted drug options and optimal drug concentrations, and discusses emerging therapies. Additionally, it highlights the variability in treatment outcomes and the potential of combination regimens to effectively manage NM in breast cancer.

EXPERT OPINION

Challenges in treating NM include debates over clinical trial end points and the management of adverse effects. Drug resistance and low response rates are significant hurdles, particularly inHER2-negative breast cancer. The development of more precise and cost-effective medications with improved selectivity is crucial. Additionally, global efforts are needed for infrastructure development and cancer control considering the diverse nature of the disease.

Intrathecal Therapy Options for Meningeal Carcinomatosis

Around 5 percent of all patients with metastatic breast cancer go on to develop distant metastases in the meninges, also known as meningeal carcinomatosis. The median survival of these patients is between 3.5 and 4.5 months. Current treatment approaches are based on radiotherapy, systemic and intrathecal therapy. Methotrexate, liposomal cytarabine and trastuzumab are the most common substances used for intrathecal therapy. The aim of this review was to provide an overview of these intrathecal therapy options for meningeal carcinomatosis. A systematic search of the literature was carried out in PubMed using the following search terms: "meningeal metastases", "meningeal carcinomatosis", "leptomeningeal metastasis", "leptomeningeal carcinomatosis", "leptomeningeal disease", "breast cancer", "MTX", "methotrexate", "DepoCyte", "liposomal cytarabine", "trastuzumab" and "anti-HER2". This search resulted in 75 potentially relevant studies, 11 of which were included in this review after meeting the previously determined inclusion and exclusion criteria. The studies differ considerably with regards to study design, cohort size, and dosages of administered drugs. In principle, intrathecal therapy has a tolerable side-effects profile and offers promising results in terms of the median overall survival following treatment with trastuzumab for HER2-positive primary tumors. The focus when treating meningeal carcinomatosis must be on providing a multimodal individual therapeutic approach. However, comprehensive studies which compare the efficacy and side effects of individual pharmaceuticals are lacking. Because of the poor prognosis associated with meningeal carcinomatosis, an approach which treats only the symptoms (best supportive care) should always be considered and discussed with affected patients.

Brain Metastases and Leptomeningeal Disease

OBJECTIVE

Central nervous system (CNS) metastases include brain parenchymal, spinal cord, and leptomeningeal metastases. This article discusses the diagnostic and therapeutic advances of the last decade that have improved outcomes for patients with these CNS metastases.

LATEST DEVELOPMENTS

The diagnostic tools for CNS metastases, particularly leptomeningeal disease, have evolved over the past decade with respect to advancements in CSF analysis. Multiple medical therapies are now available for brain metastasis treatment that have shown CNS efficacy, including targeted therapies and antibody-drug conjugates. Molecular testing for CNS metastases has become more common and the repertoire of molecularly targeted therapies continues to expand. Advancements in radiation therapy, including improvements in stereotactic radiation techniques, whole-brain radiation with hippocampal avoidance, and proton beam radiation, have changed the radiation management of patients with CNS metastases. New intrathecal agents are currently being tested for the management of leptomeningeal metastases.

ESSENTIAL POINTS

CNS metastases are far more common than primary brain tumors and are increasing in prevalence in the setting of improved treatments and prolonged survival in patients with systemic cancers. There have been many changes in the diagnostics and treatment of CNS metastases, yielding subsequent improvements in patient outcomes with further advancements on the horizon.

Intrathecal Catheter for Chemotherapy in Leptomeningeal Carcinomatosis From HER2-Negative Metastatic Breast Cancer

PURPOSE

Most oncological treatments for leptomeningeal metastasis (LM) do not cross the blood-brain barrier (BBB). One therapeutic option is intrathecal (IT) chemotherapy. Both the brain-implanted Omaya reservoir and lumbar puncture (LP) are classic routes for IT chemotherapy delivery. An intrathecal catheter (IC) connected to a subcutaneous port is a recently developed option for the management of chemotherapy infusions. It is essential to evaluate the efficacy and safety of chemotherapy infusion using such device.

METHODS

We conducted a retrospective monocentric study within Institut de cancerologie de l'Ouest at Angers, including all patients with advanced breast cancer (aBC) with LM implanted with an IT device for IT chemotherapy between January 2013 and May 2020. The primary endpoint was overall survival (OS) and secondary endpoints included surgical feasibility, patient safety, and progression-free survival (PFS). The catheter was inserted through an LP, the tip was positioned at the right level and connected to a subcutaneous port implanted under the skin of the anterior thoracic wall. IT chemotherapy is painless and easy for qualified nurses to administer on an outpatient basis.

RESULTS

Thirty women underwent the implantation. No failures occurred during the procedure. A total of 77% of patients reported no complications after implantation. Only three complications required surgical treatment. The median number of IT chemotherapy courses per patient was 8 (range, 2-27). The tolerance profile for iterative IT chemotherapy was manageable in ambulatory care. With a median follow-up of 76.5 months (95% confidence interval [CI], 11.6-not available), the median OS was 158 days (95% CI, 87-235), and the median PFS was 116 days (95% CI, 58-174).

CONCLUSION

Infusing chemotherapy using an implanted catheter is an efficient option for managing IT chemotherapy with a good tolerance profile. Patient-reported outcomes for the evaluation of IT chemotherapy toxicity are currently being developed.

A Minimal PBPK Model for Plasma and Cerebrospinal Fluid Pharmacokinetics of Trastuzumab after Intracerebroventricular Administration in Patients with HER2-Positive Brain Metastatic Localizations

BACKGROUND

Dosing regimens of trastuzumab administered by intracerebroventricular (icv) route to patients with HER2-positive brain localizations remain empirical. The objectives of this study were to describe pharmacokinetics (PK) of trastuzumab in human plasma and cerebrospinal fluid (CSF) after simultaneous icv and intravenous (iv) administration using a minimal physiologically-based pharmacokinetic model (mPBPK) and to perform simulations of alternative dosing regimens to achieve therapeutic concentrations in CSF.

METHODS

Plasma and CSF PK data were collected in two patients with HER2-positive brain localizations. A mPBPK model for mAbs consisting of four compartments (tight and leaky tissues, plasma and lymph) was enriched by an additional compartment for ventricular CSF. The comparison between observed and model-predicted concentrations was evaluated using prediction error (PE).

RESULTS

The developed mPBPK model described plasma and CSF trastuzumab concentrations reasonably well with mean PE for plasma and CSF data of 41.8% [interquartile range, IQR = -9.48; 40.6] and 18.3% [-36.7; 60.6], respectively, for patient 1 and 11.4% [-10.8; 28.7] and 22.5% [-27.7; 77.9], respectively, for patient 2. Trastuzumab showed fast clearance from CSF to plasma with Cmin,ss of 0.56 and 0.85 mg/L for 100 and 150 mg q1wk, respectively. Repeated dosing of 100 and 150 mg q3day resulted in Cmin,ss of 10.3 and 15.4 mg/L, respectively. Trastuzumab CSF target concentrations are achieved rapidly and maintained above 60 mg/L from 7 days after a continuous perfusion at 1.0 mg/h.

CONCLUSION

Continuous icv infusion of trastuzumab at 1.0 mg/h could be an alternative dosing regimen to rapidly achieve intraventricular CSF therapeutic concentrations.

New strategies for the treatment of breast cancer with leptomeningeal metastasis

PURPOSE OF REVIEW

Leptomeningeal metastasis is a complication of metastatic breast cancer that has a rising incidence likely due to the increased availability of novel systemic therapies, which have improved survival with better extracranial disease control but with limited intracranial efficacy. A poor prognosis of less than 6 months has historically been associated with leptomeningeal metastasis and it is often an exclusion factor for enrollment in clinical trials. There are limited evidence-based data supporting use of therapeutics in leptomeningeal metastasis patients and recommendations are largely derived from retrospective reports and small prospective studies. However, in recent years, there has been a surge in effective modern therapeutics with promising intracranial activity.

RECENT FINDINGS

The study aims to review the most recent updates in the management of leptomeningeal metastasis in breast cancer. We discuss the effectiveness and limitations of intrathecal administration, predictive biomarkers in the cerebrospinal fluid, proton radiation therapy and promising new systemic therapies such as antibody drug conjugates.

SUMMARY

Ongoing development of clinical trials that allow inclusion of leptomeningeal metastasis are essential for establishing efficacy potential and discovering new treatment options in this population of great unmet need.

Leptomeningeal metastasis from solid tumours: EANO-ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up

•This Clinical Practice Guideline provides recommendations for managing leptomeningeal metastases from solid tumours. •The guideline covers clinical, imaging and cytological diagnosis, staging and risk assessment, treatment and follow-up. •A treatment and management algorithm is provided. •The author panel encompasses a multidisciplinary group of experts from different institutions and countries in Europe. •Recommendations are based on available scientific data and the authors’ collective expert opinion.

HER2+ esophageal carcinoma leptomeningeal metastases treated with intrathecal trastuzumab regimen

Materials & methods: We recently reported the largest trial of breast cancer patients with HER2 positive leptomeningeal metastases (LM) treated with trastuzumab. An additional treatment indication was explored as part of a single institution retrospective case series of HER2 positive esophageal adenocarcinoma LM (n = 2). Results: One patient received intrathecal trastuzumab (80 mg twice weekly) as part of their treatment regimen with durable long-term response and clearance of circulating tumor cells in the cerebral spinal fluid. The other patient demonstrated rapid progression and death as previously described in the literature. Conclusion: Intrathecal trastuzumab is a well-tolerated and reasonable therapeutic option worthy of further exploration for patients with HER2 positive esophageal carcinoma LM. An associative, but not a causal relationship, can be made regarding therapeutic intervention.

AGO Recommendations for the Diagnosis and Treatment of Patients with Locally Advanced and Metastatic Breast Cancer: Update 2023

The Breast Committee of the Arbeitsgemeinschaft Gynäkologische Onkologie (German Gynecological Oncology Group, AGO) presents the 2023 update of the evidence-based recommendations for the diagnosis and treatment of patients with locally advanced and metastatic breast cancer (mBC).

Diagnostic and Therapeutic Updates in Leptomeningeal Disease

PURPOSE OF REVIEW

Leptomeningeal disease (LMD) is a devastating complication of advanced metastatic cancer associated with a poor prognosis and limited treatment options. This study reviews the current understanding of the clinical presentation, pathogenesis, diagnosis, and treatment of LMD. We highlight opportunities for advances in this disease.

RECENT FINDINGS

In recent years, the use of soluble CSF biomarkers has expanded, suggesting improved sensitivity over traditional cytology, identification of targetable mutations, and potential utility for monitoring disease burden. Recent studies of targeted small molecules and intrathecal based therapies have demonstrated an increase in overall and progression-free survival. In addition, there are several ongoing trials evaluating immunotherapy in LMD. Though overall prognosis of LMD remains poor, studies suggest a potential role for soluble CSF biomarkers in diagnosis and management and demonstrate promising findings in patient outcomes with targeted therapies for specific solid tumors. Despite these advances, there continues to be a gap of knowledge in this disease, emphasizing the importance of inclusion of LMD patients in clinical trials.

Leptomeningeal Metastasis: A Review of the Pathophysiology, Diagnostic Methodology, and Therapeutic Landscape

The present review aimed to establish an understanding of the pathophysiology of leptomeningeal disease as it relates to late-stage development among different cancer types. For our purposes, the focused metastatic malignancies include breast cancer, lung cancer, melanoma, primary central nervous system tumors, and hematologic cancers (lymphoma, leukemia, and multiple myeloma). Of note, our discussion was limited to cancer-specific leptomeningeal metastases secondary to the aforementioned primary cancers. LMD mechanisms secondary to non-cancerous pathologies, such as infection or inflammation of the leptomeningeal layer, were excluded from our scope of review. Furthermore, we intended to characterize general leptomeningeal disease, including the specific anatomical infiltration process/area, CSF dissemination, manifesting clinical symptoms in patients afflicted with the disease, detection mechanisms, imaging modalities, and treatment therapies (both preclinical and clinical). Of these parameters, leptomeningeal disease across different primary cancers shares several features. Pathophysiology regarding the development of CNS involvement within the mentioned cancer subtypes is similar in nature and progression of disease. Consequently, detection of leptomeningeal disease, regardless of cancer type, employs several of the same techniques. Cerebrospinal fluid analysis in combination with varied imaging (CT, MRI, and PET-CT) has been noted in the current literature as the gold standard in the diagnosis of leptomeningeal metastasis. Treatment options for the disease are both varied and currently in development, given the rarity of these cases. Our review details the differences in leptomeningeal disease as they pertain through the lens of several different cancer subtypes in an effort to highlight the current state of targeted therapy, the potential shortcomings in treatment, and the direction of preclinical and clinical treatments in the future. As there is a lack of comprehensive reviews that seek to characterize leptomeningeal metastasis from various solid and hematologic cancers altogether, the authors intended to highlight not only the overlapping mechanisms but also the distinct patterning of disease detection and progression as a means to uniquely treat each metastasis type. The scarcity of LMD cases poses a barrier to more robust evaluations of this pathology. However, as treatments for primary cancers have improved over time, so has the incidence of LMD. The increase in diagnosed cases only represents a small fraction of LMD-afflicted patients. More often than not, LMD is determined upon autopsy. The motivation behind this review stems from the increased capacity to study LMD in spite of scarcity or poor patient prognosis. In vitro analysis of leptomeningeal cancer cells has allowed researchers to approach this disease at the level of cancer subtypes and markers. We ultimately hope to facilitate the clinical translation of LMD research through our discourse.

Building Team Medicine in the Management of CNS Metastases

CNS metastases are often terminal for cancer patients and occur at an approximately 10-fold higher rate than primary CNS tumors. The incidence of these tumors is approximately 70,000-400,000 cases annually in the US. Advances that have occurred over the past two decades have led to more personalized treatment approaches. Newer surgical and radiation techniques, as well as targeted and immune therapies, have enanled patient to live longer, thus increasing the risk for the development of CNS, brain, and leptomeningeal metastases (BM and LM). Patients who develop CNS metastases have often been heavily treated, and options for future treatment could best be addressed by multidisciplinary teams. Studies have indicated that patients with brain metastases have improved survival outcomes when cared for in high-volume academic institutions using multidisciplinary teams. This manuscript discusses a multidisciplinary approach for both parenchymal brain metastases as well as leptomeningeal metastases implemented in three academic institutions. Additionally, with the increasing development of healthcare systems, we discuss optimizing the management of CNS metastases across healthcare systems and integrating basic and translational science into our clinical care to further improve outcomes. This paper summarizes the existing therapeutic approaches to the treatment of BM and LM and discusses novel and emerging approaches to optimizing access to neuro-oncologic care while simultaneously integrating multidisciplinary teams in the care of patients with BM and LM.

Intrathecal trastuzumab versus alternate routes of delivery for HER2-targeted therapies in patients with HER2+ breast cancer leptomeningeal metastases

BACKGROUND

Patients with HER2+ breast cancer (BC) frequently develop leptomeningeal metastases (LM). While HER2-targeted therapies have demonstrated efficacy in the neoadjuvant, adjuvant, and metastatic settings, including for parenchymal brain metastases, their efficacy for patients with LM has not been studied in a randomized controlled trial. However, several single-armed prospective studies, case series and case reports have studied oral, intravenous, or intrathecally administered HER2-targeted therapy regimens for patients with HER2+ BC LM.

METHODS

We conducted a systematic review and meta-analysis of individual patient data to evaluate the efficacy of HER2-targeted therapies in HER2+ BC LM in accordance with PRISMA guidelines. Targeted therapies evaluated were trastuzumab (intrathecal or intravenous), pertuzumab, lapatinib, neratinib, tucatinib, trastuzumab-emtansine and trastuzumab-deruxtecan. The primary endpoint was overall survival (OS), with CNS-specific progression-free survival (PFS) as a secondary endpoint.

RESULTS

7780 abstracts were screened, identifying 45 publications with 208 patients, corresponding to 275 lines of HER2-targeted therapy for BC LM which met inclusion criteria. In univariable and multivariable analyses, we observed no significant difference in OS and CNS-specific PFS between intrathecal trastuzumab compared to oral or intravenous administration of HER2-targeted therapy. Anti-HER2 monoclonal antibody-based regimens did not demonstrate superiority over HER2 tyrosine kinase inhibitors. In a cohort of 15 patients, treatment with trastuzumab-deruxtecan was associated with prolonged OS compared to other HER2-targeted therapies and compared to trastuzumab-emtansine.

CONCLUSIONS

The results of this meta-analysis, comprising the limited data available, suggest that intrathecal administration of HER2-targeted therapy for patients with HER2+ BC LM confers no additional benefit over oral and/or IV treatment regimens. Although the number of patients receiving trastuzumab deruxtecan in this cohort is small, this novel agent offers promise for this patient population and requires further investigation in prospective studies.

Modern Management and Diagnostics in HER2+ Breast Cancer with CNS Metastasis

Patients with HER2-positive breast cancer have seen improved survival and outcomes over the past two decades. As patients live longer, the incidence of CNS metastases has increased in this population. The authors' review outlines the most current data in HER2-positive brain and leptomeningeal metastases and discuss the current treatment paradigm in this disease. Up to 55% of HER2-positive breast cancer patients go on to experience CNS metastases. They may present with a variety of focal neurologic symptoms, such as speech changes or weakness, and may also have more diffuse symptoms related to high intracranial pressure, such as headaches, nausea, or vomiting. Treatment can include focal treatments, such as surgical resection or radiation (focal or whole-brain radiation), as well as systemic therapy options or even intrathecal therapy in the case of leptomeningeal disease. There have been multiple advancements in systemic therapy for these patients over the past few years, including the availability of tucatinib and trastuzumab-deruxtecan. Hope remains high as clinical trials for CNS metastases receive greater attention and as other HER2-directed methods are being studied in clinical trials with the goal of better outcomes for these patients.