Early rhombic lip Protogenin+ve stem cells in a human-specific neurovascular niche initiate and maintain group 3 medulloblastoma.

We identify a population of Protogenin-positive (PRTG+ve) MYChigh NESTINlow stem cells in the four-week-old human embryonic hindbrain that subsequently localizes to the ventricular zone of the rhombic lip (RLVZ). Oncogenic transformation of early Prtg+ve rhombic lip stem cells initiates group 3 medulloblastoma (Gr3-MB)-like tumors. PRTG+ve stem cells grow adjacent to a human-specific interposed vascular plexus in the RLVZ, a phenotype that is recapitulated in Gr3-MB but not in other types of medulloblastoma. Co-culture of Gr3-MB with endothelial cells promotes tumor stem cell growth, with the endothelial cells adopting an immature phenotype. Targeting the PRTGhigh compartment of Gr3-MB in vivo using either the diphtheria toxin system or chimeric antigen receptor T cells constitutes effective therapy. Human Gr3-MBs likely arise from early embryonic RLVZ PRTG+ve stem cells inhabiting a specific perivascular niche. Targeting the PRTGhigh compartment and/or the perivascular niche represents an approach to treat children with Gr3-MB.

Failure of human rhombic lip differentiation underlies medulloblastoma formation.

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain1-4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage5-8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES+KI67+ unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB.

Stereotactic radiosurgery versus whole brain radiotherapy in patients with intracranial metastatic disease and small-cell lung cancer: a systematic review and meta-analysis.

BACKGROUND: Patients with small-cell lung cancer (SCLC) are at high risk for intracranial metastatic disease (IMD). Although stereotactic radiosurgery (SRS) has supplanted whole brain radiotherapy (WBRT) as first-line treatment for IMD in most solid cancers, WBRT remains first-line treatment for IMD in patients with SCLC. We aimed to evaluate the efficacy of SRS in comparison with WBRT and assess treatment outcomes following SRS. METHODS: In this systematic review and meta-analysis, we searched MEDLINE, Embase, CENTRAL, and grey literature sources for controlled trials and cohort studies published in English reporting on SRS for IMD treatment in patients with SCLC from inception to March 23, 2022. Studies were excluded that did not report on SRS for IMD secondary to SCLC. Summary data were extracted. The primary outcome was overall survival, presented as pooled hazard ratios (HR) through random-effects meta-analysis for studies comparing SRS with WBRT with or without SRS boost, and as medians for single-arm SRS studies. This study is registered with the Open Science Framework, DOI 10.17605/OSF.IO/8M4HC, and PROSPERO, CRD42021258197. FINDINGS: Of 3823 identified records, 31 were eligible for inclusion; seven were included in the meta-analysis. Overall survival following SRS was longer than following WBRT with or without SRS boost (HR 0·85; 95% CI 0·75-0·97; n=7 studies; n=18 130 patients), or WBRT alone (0·77; 0·72-0·83; n=7 studies; n=16 961 patients), but not WBRT plus SRS boost (1·17, 0·78-1·75; n=4 studies; n=1167 patients). Using single-arm studies, pooled median overall survival from SRS was 8·99 months (95% CI 7·86-10·16; n=14 studies; n=1682 patients). Between-study heterogeneity was considerable when pooled among all comparative studies (I2=71·9%). INTERPRETATION: These results suggest survival outcomes are equitable following treatment with SRS compared with WBRT in patients with SCLC and IMD. Future prospective studies should focus on tumour burden and differences in local and distant intracranial progression between WBRT-treated and SRS-treated patients with SCLC. FUNDING: None.

Erythroblastic oncogene B-2 status and intracranial metastatic disease in patients with gastrointestinal cancer: a systematic review.

PURPOSE: The incidence of intracranial metastatic disease (IMD) in patients with gastrointestinal (GI) cancers is rising. Expression of the erythroblastic oncogene B-2 (ERBB2) is associated with an in increased risk of IMD in patients with breast cancer. The implications of ERBB2 expression for IMD risk in patients with GI cancers is less clear. The objective of this systematic review was to determine the incidence of IMD and OS in patients with ERBB2+ gastrointestinal cancers. METHODS: A literature search of MEDLINE, EMBASE, CENTRAL, and grey literature sources was conducted from date of database inception to July 2021. Included studies reported outcomes on patients with IMD secondary to ERBB2 GI cancers. RESULTS: Fourteen cohort studies met inclusion criteria, of which thirteen were retrospective. Eleven studies reported on gastric, esophageal, or gastroesophageal junction cancers. Three studies directly compared incidence of IMD based on ERBB2 status and among these, ERBB2+ patients had a higher incidence of IMD. One study indicated that ERBB2+ patients had significantly longer OS from the times of primary cancer (P = .015) and IMD diagnosis (P = .01), compared with patients with ERBB2- disease. CONCLUSIONS: In this systematic review, patients with ERBB2+ GI cancer were more likely to develop IMD. Future study is required on the prognostic and predictive value of ERBB2 status in patients with GI cancers.

Brain metastasis burden and management in patients with small cell lung cancer in Canada: a retrospective, population-based cohort study.

Background: Patients with small cell lung cancer (SCLC) have historically been characterised by poor overall survival (OS) and high risk for brain metastasis (BM), but large-scale real-world evidence on clinical presentation and treatment in this population is lacking. Our aim was to describe the clinical characteristics and outcomes of patients with SCLC and BM in Ontario, Canada. Methods: This population-based, retrospective cohort study included all patients in Ontario, Canada, who were diagnosed with SCLC between April 1, 2010, and March 31, 2018. Data were analysed between June 2, 2022, and December 20, 2023. Patients with second cancer diagnosis were excluded. Patients were identified and data retrieved from the Institute for Clinical Evaluative Sciences (ICES) databases. Kaplan-Meier and multivariable Cox regression analyses were performed to compare OS between patient cohorts stratified by disease stage, BM diagnosis, and intracranial treatment modality. Propensity score-matching based on age, disease stage, time to BM, and receipt of chemotherapy was performed to compare OS between intracranial treatment modalities. Findings: 8705 patients were included (male: 4433, female: 4272). Median age at diagnosis was 68 years (interquartile range, IQR, 61-75). Median OS of all patients was 7.46 months (95% confidence interval, CI, 7.23-7.69). 32% (n = 2686) of patients developed BM (synchronous, 43.7%; asynchronous, 56.3%) with median OS of 9.76 months (95% CI, 9.36-10.22). 102 (4%), 1654 (62%), and 930 (35%) patients received stereotactic radiosurgery (SRS), whole brain radiation therapy (WBRT), or no treatment, respectively, for their BM in the first-line setting or after prophylactic cranial irradiation (PCI). In propensity score-matched analyses, OS from time of BM diagnosis was non-inferior between SRS- and WBRT-treated cohorts among patients who did not receive PCI (hazard ratio, HR, 0.68, 95% CI, 0.44-1.06, p = 0.091, n = 86) and in favour of SRS for those who received PCI prior to BM development (HR, 0.47, 95% CI, 0.31-0.72, p = 0.0042, n = 112). Interpretation: OS for patients with SCLC remains poor, and many patients present with BM. With careful selection, patients with SCLC and BM may benefit from SRS treatment. Future research should incorporate information on burden of intracranial disease and novel immunotherapies. Funding: None.

Re-examining prophylactic cranial irradiation in small cell lung cancer: a systematic review and meta-analysis.

Background: Patients with small cell lung cancer (SCLC) are at high risk for brain metastases. Prophylactic cranial irradiation (PCI) is recommended in this population to reduce the incidence of brain metastases and prolong survival. We aimed to assesses the efficacy of PCI in this population in the era of routine brain imaging. To our knowledge, this is the first systematic review and meta-analysis to examine the use among patients who were radiographically confirmed not to have brain metastases after completion of first-line therapy. Methods: In this systematic review and meta-analysis, cohort studies and controlled trials reporting on the use of PCI for patients SCLC were identified in EMBASE, MEDLINE, CENTRAL, and grey literature sources. The literature search was conducted on November 12, 2023. Summary data were extracted. Random-effects meta-analyses pooled hazard ratios (HR) for the primary outcome of overall survival between PCI and no intervention groups. This study is registered with the Open Science Framework, DOI:10.17605/OSF.IO/BC359, and PROSPERO, CRD42021249466. Findings: Of 4318 identified records, 223 were eligible for inclusion. 109 reported on overall survival in formats amenable to meta-analysis; PCI was associated with longer survival in all patients with SCLC (HR 0.59; 95% CI, 0.55-0.63; p < 0.001; n = 56,770 patients), patients with limited stage disease (HR 0.60; 95% CI, 0.55-0.65; p < 0.001; n = 78 studies; n = 27,137 patients), and patients with extensive stage disease (HR 0.59; 95% CI, 0.51-0.70; p < 0.001; n = 28 studies; n = 26,467 patients). Between-study heterogeneity was significant when pooled amongst all studies (I2 = 73.6%; 95% CI 68.4%-77.9%). Subgroup analysis did not reveal sources of heterogeneity. In a subgroup analysis on studies that used magnetic resonance imaging to exclude presence of brain metastases at restaging among all patients, overall survival did not differ significantly between patients who did or did not receive PCI (HR 0.74; 95% CI, 0.52-1.05; p = 0.08; n = 9 studies; n = 1384 patients). Interpretation: Our findings suggested that administration of PCI is associated with a survival benefit, but not when considering studies that radiographically confirmed absence of brain metastases, suggesting that the survival benefit conferred by PCI might be therapeutic rather than prophylactic. Funding: No funding.

Association of Brain Metastases With Survival in Patients With Limited or Stable Extracranial Disease: A Systematic Review and Meta-analysis.

Importance: Intracranial metastatic disease (IMD) is a severe complication of cancer with profound prognostic implications. Patients with IMD in the setting of limited or stable extracranial disease (IMD-SE) may represent a unique and understudied subset of patients with IMD with superior prognosis. Objective: To evaluate overall survival (OS), progression-free survival (PFS), and intracranial PFS (iPFS) in patients with IMD-SE secondary to any primary cancer. Data Sources: Records were identified from MEDLINE, EMBASE, CENTRAL, and gray literature sources from inception to June 21, 2021. Study Selection: Studies in English reporting OS, PFS, or iPFS in patients with IMD-SE (defined as IMD and ≤2 extracranial metastatic sites) and no prior second-line chemotherapy or brain-directed therapy were selected. Data Extraction and Synthesis: Author, year of publication, type of study, type of primary cancer, and outcome measures were extracted. Random-effects meta-analyses were performed to estimate effect sizes, and subgroup meta-analysis and metaregression were conducted to measure between-study differences in February 2022. Main Outcomes and Measures: The primary end point was OS described as hazard ratios (HRs) and medians for comparative and single-group studies, respectively. Secondary end points were PFS and iPFS. Results: Overall, 68 studies (5325 patients) were included. IMD-SE was associated with longer OS (HR, 0.52; 95% CI, 0.39-0.70) and iPFS (HR, 0.63; 95% CI, 0.52-0.76) compared with IMD in the setting of progressive extracranial disease. The weighted median OS estimate for patients with IMD-SE was 17.9 months (95% CI, 16.4-22.0 months), and for patients with IMD-PE it was 8.0 months (95% CI, 7.2-12.8 months). Pooled median OS for all patients with IMD-SE was 20.9 months (95% CI, 16.35-25.98 months); for the subgroup with breast cancer it was 20.2 months (95% CI, 10.43-38.20 months), and for non-small cell lung cancer it was 27.5 months (95% CI, 18.27-49.66 months). Between-study heterogeneity for OS and iPFS were moderate (I2 = 56.5%) and low (I2 = 0%), respectively. Conclusions and Relevance: In this systematic review and meta-analysis of patients with IMD-SE, limited systemic disease was associated with improved OS and iPFS. Future prospective trials should aim to collect granular information on the extent of extracranial disease to identify drivers of mortality and optimal treatment strategies in patients with brain metastases.

Assessing the Association of Targeted Therapy and Intracranial Metastatic Disease.

IMPORTANCE: Targeted therapies have been hypothesized to prolong survival in the treatment of patients with intracranial metastatic disease (IMD) but, paradoxically, increase IMD incidence by improving systemic disease control and prolonging survival from the primary tumor. The real-world benefits of targeted therapy in treating patients with IMD are unclear, as clinical trials have excluded patients with IMD and lacked end points that report intracranial outcomes. OBJECTIVE: To assess the association of targeted therapy and IMD with patient survival. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study included all patients in Ontario, Canada, who received a diagnosis of IMD from April 2005 to January 2018 with primary diagnoses of breast cancer, lung or bronchus cancer, or melanoma and control patients who were matched by primary disease without IMD. The data were analyzed between March and October 2020. EXPOSURES: EGFR-, ERBB2 (HER2-), or BRAF-targeted therapy or IMD status. MAIN OUTCOMES AND MEASURES: Kaplan-Meier and multivariable Cox regression analyses were performed to compare overall survival (OS) between patient subcohorts divided by primary disease and stratified by targeted therapy receipt or IMD status. RESULTS: In this cohort of 26 676 patients with IMD and breast cancer, lung and bronchus cancer, or melanoma, 57% of patients were women, and the median age at IMD diagnosis was 64 years (interquartile range, 56-72 years). Post-IMD targeted therapy was associated with prolonged OS in patients with ERBB2-positive breast cancer (hazard ratio [HR], 0.41; 95% CI, 0.33-0.50), EGFR-positive lung cancer (HR, 0.28; 95% CI, 0.23-0.34), and BRAF-positive melanoma (HR, 0.20; 95% CI, 0.14-0.29) compared with those who did not receive post-IMD targeted therapy. The presence of IMD was associated with shorter OS in patients with metastatic ERBB2-positive breast cancer (HR, 1.80; 95% CI, 1.56-2.08) and metastatic EGFR-positive lung cancer (HR, 1.22; 95% CI, 1.08-1.39) but not metastatic BRAF-positive melanoma (HR, 1.11; 95% CI, 0.77-1.61) compared with those without IMD. CONCLUSIONS AND RELEVANCE: The findings of this cohort study suggest an association between real-world use of targeted therapies and prolonged OS in patients with IMD in the setting of ERBB2-positive breast cancer, EGFR-positive lung cancer, and BRAF-positive melanoma. Including patients with IMD in clinical trials and using end points that interrogate IMD will be critical to determine the role of targeted therapies in treating patients with IMD.

Assessment of Effectiveness and Safety of Osimertinib for Patients With Intracranial Metastatic Disease: A Systematic Review and Meta-analysis.

Importance: Intracranial metastatic disease (IMD) is a serious and life-altering complication for many patients with cancer. Targeted therapy may address the limitations of current treatments as an additional agent to achieve intracranial disease control in some patients with IMD. Given the paucity of evidence regarding effectiveness, current guidelines have not made recommendations on the use of targeted therapy. Osimertinib mesylate is a mutant epidermal growth factor receptor (EGFR) inhibitor that can penetrate the blood-brain barrier and inhibit tumor cell survival and proliferation in patients with non-small cell lung cancer (NSCLC) with specific EGFR alterations. Objective: To assess the effectiveness and safety of osimertinib in the management of IMD. Data Sources: Studies were selected from MEDLINE and Embase databases from their inception to September 20, 2019, using the following search query: (osimertinib OR mereletinib OR tagrisso OR tamarix OR azd9291) AND (brain metastases OR intracranial metastatic disease OR cns). Study Selection: Studies reporting intracranial outcomes for patients with metastatic EGFR-variant NSCLC and IMD treated with osimertinib were included in this systematic review and meta-analysis. Among 271 records identified in the systematic review, 15 studies fulfilled eligibility criteria for inclusion in the meta-analysis. Data Extraction and Synthesis: Data were extracted from published studies and supplements. These data were pooled using a random-effects model. Risk of bias was assessed using the Cochrane risk of bias tool and the modified Newcastle-Ottawa Scale. Main Outcomes and Measures: Information extracted included study characteristics, intracranial effectiveness measures, and safety measures. Meta-analyses of proportions were conducted to pool estimates for central nervous system (CNS) objective response rate and CNS disease control rate. Results: Fifteen studies reporting on 324 patients were included in the meta-analysis. The CNS objective response rate was 64% (95% CI, 53%-76%; n = 195), and CNS disease control rate was 90% (95% CI, 85%-93%; n = 246). Included studies reported complete intracranial response rates of 7% to 23%, median best decrease in intracranial lesion size of -40% to -64%, and Common Terminology Criteria for Adverse Events (version 3.0) grade 3 or higher adverse event rates of 19% to 39%. Subgroup analyses did not reveal additional sources of heterogeneity. Conclusions and Relevance: Findings reported herein support a potential role for osimertinib in the treatment of patients with metastatic EGFR-variant NSCLC and IMD treated with osimertinib. Clinical decision makers would benefit from the inclusion of patients with IMD in future trials to identify factors that predict responses to targeted therapy.

HER2-targeted therapy prolongs survival in patients with HER2-positive breast cancer and intracranial metastatic disease: a systematic review and meta-analysis.

BACKGROUND: Intracranial metastatic disease (IMD) is a serious and known complication of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The role of targeted therapy for patients with HER2-positive breast cancer and IMD remains unclear. In this study, we sought to evaluate the effect of HER2-targeted therapy on IMD from HER2-positive breast cancer. METHODS: We searched MEDLINE, EMBASE, CENTRAL, and gray literature sources for interventional and observational studies reporting survival, response, and safety outcomes for patients with IMD receiving HER2-targeted therapy. We pooled outcomes through meta-analysis and examined confounder effects through forest plot stratification and meta-regression. Evidence quality was evaluated using GRADE (PROSPERO CRD42020161209). RESULTS: A total of 97 studies (37 interventional and 60 observational) were included. HER2-targeted therapy was associated with prolonged overall survival (hazard ratio [HR] 0.47; 95% confidence interval [CI], 0.39-0.56) without significantly prolonged progression-free survival (HR 0.52; 95% CI, 0.27-1.02) versus non-targeted therapy; the intracranial objective response rate was 19% (95% CI, 12-27%), intracranial disease control rate 62% (95% CI, 55-69%), intracranial complete response rate 0% (95% CI, 0-0.01%), and grade 3+ adverse event rate 26% (95% CI, 11-45%). Risk of bias was high in 40% (39/97) of studies. CONCLUSION: These findings support a potential role for systemic HER2-targeted therapy in the treatment of patients with IMD from HER2-positive metastatic breast cancer.

The Impact of Targeted Therapy on Intracranial Metastatic Disease Incidence and Survival.

Intracranial metastatic disease (IMD) is a common and severe complication of primary cancers. Current treatment options for IMD include surgical resection and radiation therapy, although there has been recent interest in targeted therapy in the management of IMD. As of yet, insufficient data exist to support the recommendation of targeted therapies in the treatment of IMD. Paradoxically, targeted therapy has been hypothesized to play a role in the development of IMD in patients with primary cancers. This is based on the observations that patients who receive targeted therapy for primary cancer experience prolonged survival, and that prolonged survival has been associated with increased incidence of IMD. Few data exist to clarify if treatment of primary cancers with targeted therapies influences IMD incidence. Here, we discuss the role of targeted therapy in IMD management, review the current literature on IMD incidence and targeted therapy use in primary cancer, and propose the need for future studies to inform physicians in choosing treatment options and counseling patients.