Arrested development: the dysfunctional life history of medulloblastoma.

Medulloblastoma is a heterogeneous embryonal tumor of the cerebellum comprised of four distinct molecular subgroups that differ in their developmental origins, genomic landscapes, clinical presentation, and survival. Recent characterization of the human fetal cerebellum at single-cell resolution has propelled unprecedented insights into the cellular origins of medulloblastoma subgroups, including those underlying previously elusive groups 3 and 4. In this review, the molecular pathogenesis of medulloblastoma is examined through the lens of cerebellar development.

Triptolide and its prodrug Minnelide target high-risk MYC-amplified medulloblastoma in preclinical models.

Most children with medulloblastoma (MB) achieve remission, but some face very aggressive metastatic tumors. Their dismal outcome highlights the critical need to advance therapeutic approaches that benefit such high-risk patients. Minnelide, a clinically relevant analog of the natural product triptolide, has oncostatic activity in both preclinical and early clinical settings.

Melanoma antigens in pediatric medulloblastoma contribute to tumor heterogeneity and species-specificity of group 3 tumors.

Background: Medulloblastoma (MB) is the most malignant childhood brain cancer. Group 3 MB subtype accounts for about 25% of MB diagnoses and is associated with the most unfavorable outcomes. Herein, we report that more than half of group 3 MB tumors express melanoma antigens (MAGEs), which are potential prognostic and therapeutic markers.

Group 3 medulloblastoma transcriptional networks collapse under domain specific EP300/CBP inhibition.

Chemical discovery efforts commonly target individual protein domains. Many proteins, including the EP300/CBP histone acetyltransferases (HATs), contain several targetable domains. EP300/CBP are critical gene-regulatory targets in cancer, with existing high potency inhibitors of either the catalytic HAT domain or protein-binding bromodomain (BRD).

CAR T-cell Design-dependent Remodeling of the Brain Tumor Immune Microenvironment Modulates Tumor-associated Macrophages and Anti-glioma Activity.

Unlabelled: Understanding the intricate dynamics between adoptively transferred immune cells and the brain tumor immune microenvironment (TIME) is crucial for the development of effective T cell-based immunotherapies. In this study, we investigated the influence of the TIME and chimeric antigen receptor (CAR) design on the anti-glioma activity of B7-H3-specific CAR T-cells. Using an immunocompetent glioma model, we evaluated a panel of seven fully murine B7-H3 CARs with variations in transmembrane, costimulatory, and activation domains.

Intrathecal delivery of nanoparticle PARP inhibitor to the cerebrospinal fluid for the treatment of metastatic medulloblastoma.

The morbidity associated with pediatric medulloblastoma, in particular in patients who develop leptomeningeal metastases, remains high in the absence of effective therapies. Administration of substances directly into the cerebrospinal fluid (CSF) is one approach to circumvent the blood-brain barrier and focus delivery of drugs to the site of tumor. However, high rates of CSF turnover prevent adequate drug accumulation and lead to rapid systemic clearance and toxicity.

CAR T-cell design dependent remodeling of the brain tumor immune microenvironment identify macrophages as key players that inhibit or promote anti-tumor activity.

Understanding interactions between adoptively transferred immune cells and the tumor immune microenvironment (TIME) is critical for developing successful T-cell based immunotherapies. Here we investigated the impact of the TIME and chimeric antigen receptor (CAR) design on anti-glioma activity of B7-H3-specific CAR T-cells. We show that five out of six B7-H3 CARs with varying transmembrane, co-stimulatory, and activation domains, exhibit robust functionality .

Class I HDAC inhibitor entinostat synergizes with PLK1 inhibitors in MYC-amplified medulloblastoma cells.

Purpose: We and others have demonstrated that MYC-amplified medulloblastoma (MB) cells are susceptible to class I histone deacetylase inhibitor (HDACi) treatment. However, single drug treatment with HDACi has shown limited clinical efficacy. We hypothesized that addition of a second compound acting synergistically with HDACi may enhance efficacy.

Atypical teratoid/rhabdoid tumoroids reveal subgroup-specific drug vulnerabilities.

Atypical teratoid/rhabdoid tumors (ATRTs) represent a rare, but aggressive pediatric brain tumor entity. They are genetically defined by alterations in the SWI/SNF chromatin remodeling complex members SMARCB1 or SMARCA4. ATRTs can be further classified in different molecular subgroups based on their epigenetic profiles.

From PROTAC to inhibitor: Structure-guided discovery of potent and orally bioavailable BET inhibitors.

An X-ray structure of a CLICK chemistry-based BET PROTAC bound to BRD2(BD2) inspired synthesis of JQ1 derived heterocyclic amides. This effort led to the discovery of potent BET inhibitors displaying overall improved profiles when compared to JQ1 and birabresib. A thiadiazole derived 1q (SJ1461) displayed excellent BRD4 and BRD2 affinity and high potency in the panel of acute leukaemia and medulloblastoma cell lines.

Targeting protein folding in N-Myc-driven medulloblastoma.

Selective targeting of N-Myc-driven Sonic hedgehog (SHH) medulloblastoma has been a challenge for many years and, despite decades of research, few targeted therapy opportunities exist. Recently, Kuzuoglu-Ozturk et al. characterized the translatome of N-Myc-driven medulloblastoma as a promising therapeutic target.

Loss of phosphatase CTDNEP1 potentiates aggressive medulloblastoma by triggering MYC amplification and genomic instability.

MYC-driven medulloblastomas are highly aggressive childhood brain tumors, however, the molecular and genetic events triggering MYC amplification and malignant transformation remain elusive. Here we report that mutations in CTDNEP1, a CTD nuclear-envelope-phosphatase, are the most significantly enriched recurrent alterations in MYC-driven medulloblastomas, and define high-risk subsets with poorer prognosis. Ctdnep1 ablation promotes the transformation of murine cerebellar progenitors into Myc-amplified medulloblastomas, resembling their human counterparts.

Combination of Ribociclib with BET-Bromodomain and PI3K/mTOR Inhibitors for Medulloblastoma Treatment In Vitro and In Vivo.

Despite improvement in the treatment of medulloblastoma over the last years, numerous patients with MYC- and MYCN-driven tumors still fail current therapies. Medulloblastomas have an intact retinoblastoma protein RB, suggesting that CDK4/6 inhibition might represent a therapeutic strategy for which drug combination remains understudied. We conducted high-throughput drug combination screens in a Group3 (G3) medulloblastoma line using the CDK4/6 inhibitor (CDK4/6i) ribociclib at IC20, referred to as an anchor, and 87 oncology drugs approved by FDA or in clinical trials.

Primary cilia control translation and the cell cycle in medulloblastoma.

The primary cilium, a signaling organelle projecting from the surface of a cell, controls cellular physiology and behavior. The presence or absence of primary cilia is a distinctive feature of a given tumor type; however, whether and how the primary cilium contributes to tumorigenesis are unknown for most tumors. Medulloblastoma (MB) is a common pediatric brain cancer comprising four groups: SHH, WNT, group 3 (G3), and group 4 (G4).

Combination of Ribociclib and Gemcitabine for the Treatment of Medulloblastoma.

Group3 (G3) medulloblastoma (MB) is one of the deadliest forms of the disease for which novel treatment is desperately needed. Here we evaluate ribociclib, a highly selective CDK4/6 inhibitor, with gemcitabine in mouse and human G3MBs. Ribociclib central nervous system (CNS) penetration was assessed by in vivo microdialysis and by IHC and gene expression studies and found to be CNS-penetrant.

Phenyl-Glutarimides: Alternative Cereblon Binders for the Design of PROTACs.

Targeting cereblon (CRBN) is currently one of the most frequently reported proteolysis-targeting chimera (PROTAC) approaches, owing to favorable drug-like properties of CRBN ligands, immunomodulatory imide drugs (IMiDs). However, IMiDs are known to be inherently unstable, readily undergoing hydrolysis in body fluids. Here we show that IMiDs and IMiD-based PROTACs rapidly hydrolyze in commonly utilized cell media, which significantly affects their cell efficacy.

Patient-derived models recapitulate heterogeneity of molecular signatures and drug response in pediatric high-grade glioma.

Pediatric high-grade glioma (pHGG) is a major contributor to cancer-related death in children. In vitro and in vivo disease models reflecting the intimate connection between developmental context and pathogenesis of pHGG are essential to advance understanding and identify therapeutic vulnerabilities. Here we report establishment of 21 patient-derived pHGG orthotopic xenograft (PDOX) models and eight matched cell lines from diverse groups of pHGG.

Identification of Potent, Selective, and Orally Bioavailable Small-Molecule GSPT1/2 Degraders from a Focused Library of Cereblon Modulators.

Whereas the PROTAC approach to target protein degradation greatly benefits from rational design, the discovery of small-molecule degraders relies mostly on phenotypic screening and retrospective target identification efforts. Here, we describe the design, synthesis, and screening of a large diverse library of thalidomide analogues against a panel of patient-derived leukemia and medulloblastoma cell lines. These efforts led to the discovery of potent and novel GSPT1/2 degraders displaying selectivity over classical IMiD neosubstrates, such as IKZF1/3, and high oral bioavailability in mice.

Medulloblastoma recurrence and metastatic spread are independent of colony-stimulating factor 1 receptor signaling and macrophage survival.

Purpose: Tumor infiltration by immunosuppressive myeloid cells or tumor-associated macrophages (TAMs) contributes to tumor progression and metastasis. In contrast to their adult counterparts, higher TAM signatures do not correlate with aggressive tumor behavior in pediatric brain tumors. While prominent TAM infiltrates exist before and after radiation, the degree to which irradiated macrophages and microglia support progression or leptomeningeal metastasis remains unclear.

LC-MS/MS method for quantitation of gemcitabine and its metabolite 2',2'-difluoro-2'-deoxyuridine in mouse plasma and brain tissue: Application to a preclinical pharmacokinetic study.

A simple, sensitive, and relatively fast assay was developed and validated for the quantitation of gemcitabine (dFdC) and its major metabolite 2',2'-difluoro-2'-deoxyuridine (dFdU) in mouse plasma and brain tissue. The assay used a small sample (25 μL plasma and 5 mg brain) for extraction by protein precipitation. After dilution of the supernatant extract, 1 μL was injected into HPLC system for reverse phase chromatographic separation with a total run time of 8 min.

Thrombospondin-1 mimetics are promising novel therapeutics for MYC-associated medulloblastoma.

Background: Medulloblastoma (MB) comprises four subtypes of which group 3 MB are the most aggressive. Although overall survival for MB has improved, the outcome of group 3 MB remains dismal. C- amplification or MYC overexpression which characterizes group 3 MB is a strong negative prognostic factor and is frequently associated with metastases and relapses.

Drugging the "Undruggable" MYCN Oncogenic Transcription Factor: Overcoming Previous Obstacles to Impact Childhood Cancers.

Effective treatment of pediatric solid tumors has been hampered by the predominance of currently "undruggable" driver transcription factors. Improving outcomes while decreasing the toxicity of treatment necessitates the development of novel agents that can directly inhibit or degrade these elusive targets. MYCN in pediatric neural-derived tumors, including neuroblastoma and medulloblastoma, is a paradigmatic example of this problem.

Small-molecule screen reveals synergy of cell cycle checkpoint kinase inhibitors with DNA-damaging chemotherapies in medulloblastoma.

Medulloblastoma (MB) consists of four core molecular subgroups with distinct clinical features and prognoses. Treatment consists of surgery, followed by radiotherapy and cytotoxic chemotherapy. Despite this intensive approach, outcome remains dismal for patients with certain subtypes of MB, namely, -amplified Group 3 and -mutated SHH.