Endocrine Therapy for Leptomeningeal Metastases from ER-Positive Breast Cancer: Case Report and a Review of the Literature

Leveraging Molecular and Immune-Based Therapies in Leptomeningeal Metastases

Leptomeningeal metastases represent an aggressive stage of cancer with few durable treatment options. Improved understanding of cancer biology, neoplastic reliance on oncogenic driver mutations, and complex immune system interactions have resulted in an explosion in cancer-directed therapy in the last two decades to include small molecule inhibitors and immune checkpoint inhibitors. Most of these therapeutics are underexplored in patients with leptomeningeal metastases, limiting extrapolation of extracranial and even intracranial efficacy outcomes to the unique leptomeningeal space. Further confounding our interpretation of drug activity in the leptomeninges is an incomplete understanding of drug penetration through the blood-cerebrospinal fluid barrier of the choroid plexus. Nevertheless, a number of retrospective studies and promising prospective trials provide evidence of leptomeningeal activity of several small molecule and immune checkpoint inhibitors and underscore potential areas of further therapeutic development for patients harboring leptomeningeal disease.

Leptomeningeal Metastases: New Opportunities in the Modern Era

Leptomeningeal metastases arise from cancer cell entry into the subarachnoid space, inflicting significant neurologic morbidity and mortality across a wide range of malignancies. The modern era of cancer therapeutics has seen an explosion of molecular-targeting agents and immune-mediated strategies for patients with breast, lung, and melanoma malignancies, with meaningful extracranial disease control and improvement in patient survival. However, the clinical efficacy of these agents in those with leptomeningeal metastases remains understudied, due to the relative rarity of this patient population, the investigational challenges associated with studying this dynamic disease state, and brisk disease pace. Nevertheless, retrospective studies, post hoc analyses, and small prospective trials in the last two decades provide a glimmer of hope for patients with leptomeningeal metastases, suggesting that several cancer-directed strategies are not only active in the intrathecal space but also improve survival against historical odds. The continued development of clinical trials devoted to patients with leptomeningeal metastases is critical to establish robust efficacy outcomes in this patient population, define drug pharmacokinetics in the intrathecal space, and uncover new avenues for treatment in the face of leptomeningeal therapeutic resistance.

Leptomeningeal Metastases from Solid Tumors: Recent Advances in Diagnosis and Molecular Approaches

Leptomeningeal metastases (LM) from solid tumors represent an unmet need of increasing importance due to an early use of MRI for diagnosis and improvement of outcome of some molecular subgroups following targeted agents and immunotherapy. In this review, we first discussed factors limiting the efficacy of targeted agents in LM, such as the molecular divergence between primary tumors and CNS lesions and CNS barriers at the level of the normal brain, brain tumors and CSF. Further, we reviewed pathogenesis and experimental models and modalities, such as MRI (with RANO and ESO/ESMO criteria), CSF cytology and liquid biopsy, to improve diagnosis and monitoring following therapy. Efficacy and limitations of targeted therapies for LM from EGFR-mutant and ALK-rearranged NSCLC, HER2-positive breast cancer and BRAF-mutated melanomas are reported, including the use of intrathecal administration or modification of traditional cytotoxic compounds. The efficacy of checkpoint inhibitors in LM from non-druggable tumors, in particular triple-negative breast cancer, is discussed. Last, we focused on some recent techniques to improve drug delivery.

Endocrine therapy for the treatment of leptomeningeal carcinomatosis in luminal breast cancer: a comprehensive review

Leptomeningeal disease (LMD) represents a devastating complication of advanced breast cancer (ABC), with survival of <5 months with multimodal treatment. The role of endocrine therapy (ET), due to its favorable toxicity profile and first-line indication in luminal ABC, appears promising in the setting of LMD, where symptom stabilization and quality-of-life preservation are the main goals; however, evidenced-based data are lacking. We conducted a thorough review of published evidence, aiming to investigate the role of ET in LMD treatment in luminal ABC. Twenty-one of 342 articles, evaluating 1302 patients, met inclusion criteria. ET use was rarely reported. New targeted agents show CNS activity. Research is lacking on the role of ET and targeted agents in BC-LMD treatment.

Durable clinical benefit of letrozole in leptomeningeal metastasis of breast cancer

A case of a woman in her 60s with breast cancer, whose leptomeningeal metastasis (LM) of breast cancer improved remarkably with letrozole monotherapy, is reported. The patient complained of numbness of her left hand and hoarseness, followed by progressive asymmetric extremity weakness and a bladder and rectal disturbance. The patient had undergone surgery for left breast cancer 18 years earlier and was concerned about recurrence of breast cancer, but there were no typical findings with some imaging modalities. The third lumbar puncture showed the malignant cytology of breast cancer, and the patient was diagnosed with recurrent breast cancer. Her performance status was very poor, and it was difficult to administer systemic chemotherapy. Letrozole was started because immunohistochemistry was positive for estrogen and progesterone receptors. After 4 months of letrozole therapy, the symptoms improved gradually. LM has a poor prognosis, and there is little evidence on which to base treatment, but hormone therapy may be an option for LM when the tumor is hormone receptor-positive, slow growing, and has a small volume.

Clinicopathological and Treatment-Associated Prognostic Factors in Patients with Breast Cancer Leptomeningeal Metastases in Relation to Tumor Biology

BACKGROUND

Breast cancer (BC) is one of the solid tumors most commonly associated with leptomeningeal disease (LMD). LMD carries a devastating prognosis; however, disease presentation and prognostic factors are uncertain.

SUBJECTS, MATERIALS, AND METHODS

In order to describe patient characteristics, treatment patterns, and factors associated with survival in a contemporary multicentric cohort, 153 consecutive BC patients diagnosed with LMD at two European institutions (2002-2017) were included. Time to LMD and overall survival (OS) after LMD diagnosis were evaluated using the Kaplan-Meier method and Cox proportional hazards models.

RESULTS

Median age at LMD diagnosis was 58 years (25-84). Tumor phenotype distribution was as follows: hormone receptor (HR) positive (HR+)/human epidermal growth receptor 2 (HER2) negative 51.0%, triple-negative 15.0%, HR+/HER2 positive (HER2+) 13.1% and HR negative/HER2+ 7.2%. Most patients received active anticancer treatments (radiation therapy [RT] n = 42, systemic therapy n = 110, intrathecal treatment n = 103).Median OS was 3.9 months (95% confidence interval [CI] 2.4-5.5). Eastern Cooperative Oncology Group performance status (ECOG PS) >2, high white blood cells count, low glucose, and high protein in cerebrospinal fluid (CSF) were poor prognostic factors. Having received RT or systemic treatment was associated with better prognosis. In multivariate analysis, ECOG PS (hazard ratio 2.22, 95% CI 1.25-3.94), CSF glucose levels (hazard ratio 1.74, 95% CI 1.05-2.88), and having received systemic treatment (hazard ratio 0.17, 95% CI 0.09-0.32) were confirmed as independent prognostic factors. In HER2+ BC patients, having received systemic HER2-targeted therapy was the only factor maintaining independent prognostication (hazard ratio 0.12, 95% CI 0.02-0.67) in multivariate analysis.

CONCLUSION

Despite being limited by their retrospective nature, these results highlight the need for clinical trials in BC LMD, stratified on tumor biology.

IMPLICATIONS FOR PRACTICE

Leptomeningeal disease (LMD) is a devastating complication of breast cancer (BC), and its optimal therapy is still not defined. Here, patient characteristics, treatment patterns, and prognostic factors from a contemporary cohort of 153 BC-related LMD patients are reported. In multivariate analysis, Eastern Cooperative Oncology Group performance status, cerebrospinal fluid glucose levels, and having received systemic treatment were confirmed as independent prognostic factors in the overall population, whereas in human epidermal growth receptor 2 (HER2) positive BC patients, having received systemic HER2-targeted therapy was the only factor maintaining independent prognostication in multivariate analysis. These results highlight the need to consider stratification on tumor biology in the treatment of BC LMD.

Leptomeningeal disease: current diagnostic and therapeutic strategies

Leptomeningeal disease has become increasingly prevalent as novel therapeutic interventions extend the survival of cancer patients. Although a majority of leptomeningeal spread occurs secondary to breast cancer, lung cancer, and melanoma, a wide variety of malignancies have been reported as primary sources. Symptoms on presentation are equally diverse, often involving a combination of neurological deficits with the possibility of obstructive hydrocephalus. Diagnosis is definitively made via cerebrospinal fluid cytology for malignant cells, but neuro-imaging with high quality T1-weighted magnetic resonance imaging can aid diagnosis and localization. While leptomeningeal disease is still a terminal, late-stage complication, a variety of treatment modalities, such as intrathecal chemotherapeutics and radiation therapy, have improved median survival from 4–6 weeks to 3–6 months. Positive prognosticative factors for survival include younger age, high performance scores, and controlled systemic disease. In looking to the future, diagnostics that improve early detection and chemotherapeutics tailored to the primary malignancy will likely be the most significant advances in improving survival.

Complete response and long-term survival of leptomeningeal carcinomatosis from breast cancer with maintenance endocrine therapy

Leptomeningeal carcinomatosis carries a poor prognosis in breast cancer. Treatment modalities are geared towards tumour molecular characteristics, as well as symptoms and patient performance status. It has previously been postulated that endocrine treatments used for the treatment of metastatic breast cancer do cross the blood-brain barrier and can achieve antineoplastic effects in the central nervous system. We report a case of metastatic breast cancer in a 65-year-old woman who developed leptomeningeal carcinomatosis. She was initially treated with intrathecal methotrexate, which was stopped due to toxicity, followed by maintenance endocrine therapy. She achieved a sustained complete radiological and cerebrospinal fluid cytological response for over 9 years. She eventually passed away of ischaemic bowel unrelated to her cancer.

Endocrine Therapy for Leptomeningeal Metastases from ER-Positive Breast Cancer: Case Report and a Review of the Literature

Leptomeningeal disease is an uncommon complication of estrogen receptor positive breast cancer. While there is little consensus on the standard of care, recommendations from current clinical practice guidelines are to treat with intrathecal chemotherapy, necessitating invasive procedures and potentially resulting in a substantial incidence of serious complications and side effects. Here, we review all published evidence of the effectiveness of systemic hormonal therapy alone in treating this condition, with the advantage of requiring no invasive procedures and having virtually no serious complications or side effects. Evidence indicates that most hormonal therapies can penetrate the central nervous system and can be an effective treatment of endocrine sensitive breast cancer that is widely metastatic to the leptomeninges.