The Underlying Biology and Therapeutic Vulnerabilities of Leptomeningeal Metastases in Adult Solid Cancers

Osimertinib is associated with improved outcomes in pre-treated non-small cell lung cancer leptomeningeal metastases: A systematic review and meta-analysiss

Purpose

Leptomeningeal metastasis (LM) is a severe complication of non-small cell lung cancer (NSCLC). In patients with NSCLC LM harboring epidermal growth factor receptor (EGFR) mutations, osimertinib is favored over alternative EGFR tyrosine kinase inhibitors (TKIs). However, the efficacy of osimertinib relative to other EGFR-TKIs is not well established for patients with LM. We aimed to compare the efficacy of EGFR-TKIs in EGFR-mutated NSCLC LM.

Methods

This systematic review and meta-analysis performed according to PRISMA guidelines included studies of adult patients with EGFR-mutated NSCLC and a diagnosis of LM who received an EGFR-TKI for the treatment of LM. We searched Medline ALL, Embase, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science Core Collection. The evaluation of biases was done by using the Ottawa-Newscastle scale. The hazard ratio was used as the parameter of interest for overall survival (OS) and central nervous system-specific progression-free survival (PFS).

Results

128 publications were included with 243 patients and 282 lines of EGFR-TKI for NSCLC LM that met inclusion criteria. The median PFS in patients receiving any EGFR-TKI was 9.1 months, and the median OS was 14.5 months. In univariate analyses of the entire cohort, osimertinib treatment demonstrated significantly prolonged PFS, but not OS, compared to other EGFR-TKIs. Osimertinib demonstrated significantly prolonged PFS and OS in the subset of patients who were previously treated with EGFR-TKIs, but not in EGFR-TKI naïve patients.

Conclusion

Osimertinib is associated with improved outcomes compared to other EGFR-TKIs, particularly in patients previously treated with EGFR-TKIs. An important limitation is that most patients were derived from retrospective reports. These results highlight the need for prospective studies for this difficult-to-treat patient population.

Repurposing mebendazole against triple-negative breast cancer CNS metastasis

PURPOSE

Triple-negative breast cancer (TNBC) often metastasizes to the central nervous system (CNS) and has the highest propensity among breast cancer subtypes to develop leptomeningeal disease (LMD). LMD is a spread of cancer into leptomeningeal space that speeds up the disease progression and severely aggravates the prognosis. LMD has limited treatment options. We sought to test whether the common anti-helminthic drug mebendazole (MBZ) may be effective against murine TNBC LMD.

METHODS

A small-molecule screen involving TNBC cell lines identified benzimidazoles as potential therapeutic agents for further study. In vitro migration assays were used to evaluate cell migration capacity and the effect of MBZ. For in vivo testing, CNS metastasis was introduced into BALB/c athymic nude mice through internal carotid artery injections of brain-tropic MDA-MB-231-BR or MCF7-BR cells. Tumor growth and spread was monitored by bioluminescence imaging and immunohistochemistry. MBZ was given orally at 50 and 100 mg/kg doses. MBZ bioavailability was assayed by mass spectrometry.

RESULTS

Bioinformatic analysis and migration assays revealed higher migratory capacity of TNBC compared to other breast cancer subtypes. MBZ effectively slowed down migration of TNBC cell line MDA-MB-231 and its brain tropic derivative MDA-MB-231-BR. In animal studies, MBZ reduced leptomeningeal spread, and extended survival in brain metastasis model produced by MDA-MB-231-BR cells. MBZ did not have an effect in the non-migratory MCF7-BR model.

CONCLUSIONS

We demonstrated that MBZ is a safe and effective oral agent in an animal model of TNBC CNS metastasis. Our findings are concordant with previous efforts involving MBZ and CNS pathology and support the drug's potential utility to slow down leptomeningeal spread.

The anatomic basis of leptomeningeal metastasis

Leptomeningeal metastasis (LM), or spread of cancer to the cerebrospinal fluid (CSF)-filled space surrounding the central nervous system, is a fatal complication of cancer. Entry into this space poses an anatomical challenge for cancer cells; movement of cells between the blood and CSF is tightly regulated by the blood-CSF barriers. Anatomical understanding of the leptomeninges provides a roadmap of corridors for cancer entry. This Review describes the anatomy of the leptomeninges and routes of cancer spread to the CSF. Granular understanding of LM by route of entry may inform strategies for novel diagnostic and preventive strategies as well as therapies.

Animal models of brain and spinal cord metastases of NSCLC established using a brain stereotactic instrument

Objective

Animal models of brain and spinal cord metastases of non-small cell lung cancer were established through the intracranial injection of PC-9 Luc cells with a brain stereotaxic device. This method provides a reliable modeling method for studying brain and spinal cord metastases of non-small cell lung cancer.

Methods

PC-9 Luc cells at logarithmic growth stage were injected into the skulls of 5-week-old BALB/c nude mice at different cell volumes (30 × 104, 80 × 104) and different locations (using anterior fontanel as a location point, 1 mm from the coronal suture, and 1.5 mm from the sagittal suture on the right upper and right lower side of the skull). After 1 week of cell inoculation, fluorescence signals of tumor cells in the brain and spinal were detected using the IVIS Xenogen Imaging system. After 4 weeks, brain and spinal tissues from the nude mice were harvested. Following paraffin-embedded sectioning, HE staining was performed on the tissues.

Results

The fluorescence signals revealed that both brain and spinal cord metastasis occurred in the mice where the cells were injected at the lower right side of the skull. There was only brain metastasis in the nude mice injected with 30 × 104 cells at the upper right side of the skull. Both brain and spinal cord metastasis occurred in the nude mice injected with 80 × 104 cells. The HE staining revealed that both brain and spinal cord metastasis occurred in the mice injected with different amounts of PC-9 Luc cells, consistent with the results detected using the IVIS Xenogen Imaging system, thereby demonstrating the reliability of detecting fluorescent signals in vivo to determine tumor growth.

Conclusion

It is a reliable method to establish the animal model of brain and spinal cord metastases of non-small cell lung cancer by injecting different quantities of cells from different positions with a brain stereotaxic device. The IVIS Xenogen Imaging system has high reliability in detecting the fluorescence signals of brain and spinal cord metastatic tumors.

Repurposing mebendazole against triple-negative breast cancer leptomeningeal disease

Purpose

Triple-negative breast cancer (TNBC) is an aggressive subtype that often metastasizes to the brain. Leptomeningeal disease (LMD), a devastating brain metastasis common in TNBC, has limited treatment options. We sought to test whether the common anti-helminthic drug mebendazole (MBZ) may be effective against murine TNBC LMD.

Methods

A small-molecule screen involving TNBC cell lines identified benzimidazoles as potential therapeutic agents for further study. In vitro migration assays were used to evaluate cell migration capacity and the effect of MBZ. For in vivo testing, LMD was introduced into BALB/c athymic nude mice through internal carotid artery injections of brain-tropic MDA-MB-231-BR or MCF7-BR cells. Tumor growth and spread was monitored by bioluminescence imaging. MBZ was given orally at 50 and 100 mg/kg doses. MBZ bioavailability was assayed by mass spectrometry.

Results

Bioinformatic analysis and migration assays revealed higher migratory capacity of TNBC compared to other breast cancer subtypes. MBZ effectively slowed down migration of TNBC cell line MDA-MB-231 and its brain tropic derivative MDA-MB-231-BR. In animal studies, MBZ reduced tumor growth and extended survival in the LMD model produced by MDA-MB-231-BR cells. MBZ did not have an effect in the non-migratory MCF7-BR model.

Conclusions

We demonstrated that MBZ is a safe and effective oral agent in an animal model of TNBC LMD. Our findings are concordant with previous efforts involving MBZ and central nervous system pathology and further support the drug's potential utility as an alternative therapeutic for TNBC LMD.

Thinking (Metastasis) outside the (Primary Tumor) Box

The metastasis of tumor cells into vital organs is a major cause of death from diverse types of malignancies [...].

The Riddle of the Sphinx: Progress in Leptomeningeal Metastasis of Non-Small Cell Lung Cancer

Leptomeningeal metastasis (LM) is a serious complication of advanced non-small cell lung cancer (NSCLC), and the incidence of LM has been increasing yearly in recent times. There is no consensus on the best treatment modality for LM, which underscores a difficult problem in the management of advanced NSCLC patients. The existing treatments include molecular targeted therapy, systemic chemotherapy, local radiotherapy, antivascular tumor therapy, intrathecal chemotherapy, and immunotherapy, but their efficacy is not satisfactory. In this article, we briefly describe the clinical manifestations, diagnosis, and treatment of NSCLC-LM and discuss progress regarding evaluation of the efficacy of LM treatment to better provide a necessary reference for clinical practice and clinical trial evaluation.

ICAM2 initiates trans-blood-CSF barrier migration and stemness properties in leptomeningeal metastasis of triple-negative breast cancer

Leptomeningeal metastasis (LM) occurs when tumor cells spread to the leptomeningeal space surrounding the brain and the spinal cord, thereby causing poor clinical outcomes. The triple-negative breast cancer (TNBC) has been associated with symptoms of LM and mechanism remained unclear. Through proteomic analysis, we identified high expression of ICAM2 in leptomeningeal metastatic TNBC cells, which promoted the colonization of the spinal cord and resulted in poor survival in vivo. Two-way demonstration indicated that high levels of ICAM2 promoted blood-cerebrospinal fluid barrier (BCB) adhesion, trans-BCB migration, and stemness abilities and determined the specificity of LM in vivo. Furthermore, pull-down and antibody neutralizing assay revealed that ICAM2 determined the specificity of LM through interactions with ICAM1 in the choroid plexus epithelial cells. Therefore, neutralizing ICAM2 can attenuate the progression of LM and prolong survival in vivo. The results suggested that targeting ICAM2 is a potential therapeutic strategy for LM in TNBC.

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.

Anatomical and surgical characteristics correlate with pachymeningeal failure in patients with brain metastases after neurosurgical resection and adjuvant stereotactic radiosurgery

PURPOSE

Neurosurgery (NS) is an essential modality for large brain metastases (BM). Postoperative stereotactic radiosurgery (SRS) is the standard of care adjuvant treatment. Pachymeningeal failure (PMF) is a newly described entity, distinct from classical leptomeningeal failure (LMF), that is uniquely observed in postoperative patients treated with adjuvant SRS. We sought to identify risk factors for PMF in patients treated with NS + SRS.

METHODS

From a prospective registry (2009 to 2021), we identified all patients treated with NS + SRS. Clinical, imaging, pathological, and treatment factors were analyzed. PMF incidence was evaluated using a competing risks model.

RESULTS

144 Patients were identified. The median age was 62 (23-90). PMF occurred in 21.5% (31/144). Female gender [Hazard Ratio (HR) 2.65, p = 0.013], higher Graded Prognostic Assessment (GPA) index (HR 2.4, p < 0.001), absence of prior radiation therapy (HR N/A, p = 0.018), controlled extracranial disease (CED) (HR 3.46, p = 0.0038), and pia/dura contact (PDC) (HR 3.30, p = 0.0053) were associated with increased risk for PMF on univariate analysis. In patients with PDC, wider target volumes correlated with reduced risk of PMF. Multivariate analysis indicated PDC (HR 3.51, p = 0.0053), piecemeal resection (HR 2.38, p = 0.027), and CED (HR 3.97, p = 0.0016) independently correlated with PMF risk. PMF correlated with reduced OS (HR 2.90, p < 0.001) at a lower rate compared to LMF (HR 10.15, p < 0.001).

CONCLUSION

PMF correlates with tumor PDC and piecemeal resection in patients treated with NS + SRS. For unclear reasons, it is also associated with CED. In tumors with PDC, wider dural radiotherapy coverage was associated with a lower risk of PMF.

Early Detection of Leptomeningeal Metastases Among Patients Undergoing Spinal Stereotactic Radiosurgery

Purpose

The management of patients with advanced solid malignancies increasingly uses stereotactic body radiation therapy (SBRT). Advanced cancer patients are at risk for developing leptomeningeal metastasis (LM), a fatal complication of metastatic cancer. Cerebrospinal fluid (CSF) is routinely collected during computed tomography (CT) myelography for spinal SBRT planning, offering an opportunity for early LM detection by CSF cytology in the absence of radiographic LM or LM symptoms (subclinical LM). This study tested the hypothesis that early detection of tumor cells in CSF in patients undergoing spine SBRT portends a similarly poor prognosis compared with clinically overt LM.

Methods and Materials

We retrospectively analyzed clinical records for 495 patients with metastatic solid tumors who underwent CT myelography for spinal SBRT planning at a single institution from 2014 to 2019.

Results

Among patients planned for SBRT, 51 (10.3%) developed LM. Eight patients (1.6%) had subclinical LM. Median survival with LM was similar between patients with subclinical versus clinically evident LM (3.6 vs 3.0 months, P = .30). Patients harboring both parenchymal brain metastases and LM (29/51) demonstrated shorter survival than those with LM alone (2.4 vs 7.1 months, P = .02).

Conclusions

LM remains a fatal complication of metastatic cancer. Subclinical LM detected by CSF cytology in spine SBRT patients has a similarly poor prognosis compared with standardly detected LM and warrants consideration of central nervous system-directed therapies. As aggressive local therapies are increasingly used for metastatic patients, more sensitive CSF evaluation may further identify patients with subclinical LM and should be evaluated prospectively.

Single-cell spatial immune landscapes of primary and metastatic brain tumours

Single-cell technologies have enabled the characterization of the tumour microenvironment at unprecedented depth and have revealed vast cellular diversity among tumour cells and their niche. Anti-tumour immunity relies on cell-cell relationships within the tumour microenvironment^1,2, yet many single-cell studies lack spatial context and rely on dissociated tissues³. Here we applied imaging mass cytometry to characterize the immunological landscape of 139 high-grade glioma and 46 brain metastasis tumours from patients. Single-cell analysis of more than 1.1 million cells across 389 high-dimensional histopathology images enabled the spatial resolution of immune lineages and activation states, revealing differences in immune landscapes between primary tumours and brain metastases from diverse solid cancers. These analyses revealed cellular neighbourhoods associated with survival in patients with glioblastoma, which we leveraged to identify a unique population of myeloperoxidase (MPO)-positive macrophages associated with long-term survival. Our findings provide insight into the biology of primary and metastatic brain tumours, reinforcing the value of integrating spatial resolution to single-cell datasets to dissect the microenvironmental contexture of cancer.

The joint detection of CEA and ctDNA in cerebrospinal fluid: an auxiliary tool for the diagnosis of leptomeningeal metastases in cancer

BACKGROUND

Leptomeningeal metastases (LMs) are highly invasive which leads to poor prognosis, but the accurate diagnosis of LM is challenging. It is necessary to investigate more advanced diagnostic methods to realize precision medicine. The main purpose of this study was to select a more effective method for the auxiliary diagnosis of LM by comparing various detection methods. The secondary purpose was to explore the value of cerebrospinal fluid (CSF) tumor markers (TMs) and circulating tumor DNA (ctDNA) testing in guiding clinical treatment.

METHODS

TMs in serum and CSF of patients were detected by chemiluminescence. The ctDNA of CSF and plasma were detected by the next-generation sequencing (NGS) technology.

RESULTS

In total, 54 tumor patients participated in this study, in which 39 with LM and 15 without LM (8 with parenchymal tumor and 7 without brain metastasis). The results showed that the sensitivity and accuracy of CSF cytology isolated during the first lumbar puncture were 0.31 (95% CI 0.17-0.48) and 0.50 (95% CI 0.36-0.64), respectively. The sensitivity and accuracy of CSF_CEA were 0.71 (95% CI 0.54-0.85) and 0.78 (95% CI 0.64-0.89), which were better than those of CSF_NSE and CSF_CFRA-211. The sensitivity and accuracy of CSF_ctDNA were 0.92 (95% CI 0.79-0.98) and 0.91 (95% CI 0.80-0.97), significantly higher than that of CSF cytology (P < 0.01). The sensitivity and accuracy of CSF_CEA combined with CSF_ctDNA were 0.97 (95% CI, 0.87-1.00) and 0.94 (95% CI 0.85-0.99), which were significantly higher than the traditional methods CSF cytology (P < 0.01). For LM patients with hydrocephalus, the sensitivity of CSF ctDNA even achieved 100% (14/14).

CONCLUSION

CSF_CEA combined with CSF_ctDNA could be used to accurately distinguish patients with LM from those with no brain metastasis and from those with parenchymal tumors. CSF_ctDNA testing reveals a unique mutation profile for patients with LM. Dynamic detection of CSF TM and ctDNA can better predict the efficacy and reveal the cause of drug resistance to guide subsequent treatment.

CLINICAL TRIAL REGISTRATION

Clinical trial registration number: NCT03029065.