Coming in from the cold: overcoming the hostile immune microenvironment of medulloblastoma
Eisemann T, Wechsler-Reya RJ.
Genes Dev. 2022 May 1;36(9-10):514-532. doi: 10.1101/gad.349538.122.
Medulloblastoma is an aggressive brain tumor that occurs predominantly in children. Despite intensive therapy, many patients die of the disease, and novel therapies are desperately needed. Although immunotherapy has shown promise in many cancers, the low mutational burden, limited infiltration of immune effector cells, and immune-suppressive microenvironment of medulloblastoma have led to the assumption that it is unlikely to respond to immunotherapy. However, emerging evidence is challenging this view. Here we review recent preclinical and clinical studies that have identified mechanisms of immune evasion in medulloblastoma, and highlight possible therapeutic interventions that may give new hope to medulloblastoma patients and their families.
May 1, 2022
Conventional Therapies Deplete Brain-Infiltrating Adaptive Immune Cells in a Mouse Model of Group 3 Medulloblastoma Implicating Myeloid Cells as Favorable Immunotherapy Targets
Abbas Z, George C, Ancliffe M, Howlett M, Jones AC, Kuchibhotla M, Wechsler-Reya RJ, Gottardo NG, Endersby R.
Front Immunol. 2022 Mar 3;13:837013. doi: 10.3389/fimmu.2022.837013. eCollection 2022.
Medulloblastoma is the most common childhood brain cancer. Mainstay treatments of radiation and chemotherapy have not changed in decades and new treatment approaches are crucial for the improvement of clinical outcomes. To date, immunotherapies for medulloblastoma have been unsuccessful, and studies investigating the immune microenvironment of the disease and the impact of current therapies are limited. Preclinical models that recapitulate both the disease and immune environment are essential for understanding immune-tumor interactions and to aid the identification of new and effective immunotherapies. Using an immune-competent mouse model of aggressive Myc-driven medulloblastoma, we characterized the brain immune microenvironment and changes induced in response to craniospinal irradiation, or the medulloblastoma chemotherapies cyclophosphamide or gemcitabine. The role of adaptive immunity in disease progression and treatment response was delineated by comparing survival outcomes in wildtype C57Bl/6J and in mice deficient in Rag1 that lack mature T and B cells. We found medulloblastomas in wildtype and Rag1-deficient mice grew equally fast, and that craniospinal irradiation and chemotherapies extended survival equally in wildtype and Rag1-deficient mice, suggesting that tumor growth and treatment response is independent of T and B cells. Medulloblastomas were myeloid dominant, and in wildtype mice, craniospinal irradiation and cyclophosphamide depleted T and B cells in the brain. Gemcitabine treatment was found to minimally alter the immune populations in the brain, resulting only in a depletion of neutrophils. Intratumorally, we observed an abundance of Iba1+ macrophages, and we show that CD45high cells comprise the majority of immune cells within these medulloblastomas but found that existing markers are insufficient to clearly delineate resident microglia from infiltrating macrophages. Ultimately, brain resident and peripheral macrophages dominate the brain and tumor microenvironment and are not depleted by standard-of-care medulloblastoma therapies. These populations therefore present a favorable target for immunotherapy in combination with front-line treatments.
March 3, 2022
The current landscape of immunotherapy for pediatric brain tumors
Hwang EI, Sayour EJ, Flores CT, Grant G, Wechsler-Reya R, Hoang-Minh LB, Kieran MW, Salcido J, Prins RM, Figg JW, Platten M, Candelario KM, Hale PG, Blatt JE, Governale LS, Okada H, Mitchell DA, Pollack IF.
Nat Cancer. 2022 Jan;3(1):11-24. doi: 10.1038/s43018-021-00319-0. Epub 2022 Jan 20.
Pediatric central nervous system tumors are the most common solid malignancies in childhood, and aggressive therapy often leads to long-term sequelae in survivors, making these tumors challenging to treat. Immunotherapy has revolutionized prospects for many cancer types in adults, but the intrinsic complexity of treating pediatric patients and the scarcity of clinical studies of children to inform effective approaches have hampered the development of effective immunotherapies in pediatric settings. Here, we review recent advances and ongoing challenges in pediatric brain cancer immunotherapy, as well as considerations for efficient clinical translation of efficacious immunotherapies into pediatric settings.
January 20, 2022
Functional Precision Medicine Identifies New Therapeutic Candidates for Medulloblastoma
Rusert JM, Juarez EF, Brabetz S, Jensen J, Garancher A, Chau LQ, Tacheva-Grigorova SK, Wahab S, Udaka YT, Finlay D, Seker-Cin H, Reardon B, Gröbner S, Serrano J, Ecker J, Qi L, Kogiso M, Du Y, Baxter PA, Henderson JJ, Berens ME, Vuori K, Milde T, Cho YJ, Li XN, Olson JM, Reyes I, Snuderl M, Wong TC, Dimmock DP, Nahas SA, Malicki D, Crawford JR, Levy ML, Van Allen EM, Pfister SM, Tamayo P, Kool M, Mesirov JP, Wechsler-Reya RJ.
Cancer Res. 2020 Dec 1;80(23):5393-5407. doi: 10.1158/0008-5472.CAN-20-1655. Epub 2020 Oct 12.
Medulloblastoma is among the most common malignant brain tumors in children. Recent studies have identified at least four subgroups of the disease that differ in terms of molecular characteristics and patient outcomes. Despite this heterogeneity, most patients with medulloblastoma receive similar therapies, including surgery, radiation, and intensive chemotherapy. Although these treatments prolong survival, many patients still die from the disease and survivors suffer severe long-term side effects from therapy. We hypothesize that each patient with medulloblastoma is sensitive to different therapies and that tailoring therapy based on the molecular and cellular characteristics of patients’ tumors will improve outcomes. To test this, we assembled a panel of orthotopic patient-derived xenografts (PDX) and subjected them to DNA sequencing, gene expression profiling, and high-throughput drug screening. Analysis of DNA sequencing revealed that most medulloblastomas do not have actionable mutations that point to effective therapies. In contrast, gene expression and drug response data provided valuable information about potential therapies for every tumor. For example, drug screening demonstrated that actinomycin D, which is used for treatment of sarcoma but rarely for medulloblastoma, was active against PDXs representing Group 3 medulloblastoma, the most aggressive form of the disease. Functional analysis of tumor cells was successfully used in a clinical setting to identify more treatment options than sequencing alone. These studies suggest that it should be possible to move away from a one-size-fits-all approach and begin to treat each patient with therapies that are effective against their specific tumor. SIGNIFICANCE: These findings show that high-throughput drug screening identifies therapies for medulloblastoma that cannot be predicted by genomic or transcriptomic analysis.
October 13, 2020
Biallelic loss of GNAS in a patient with pediatric medulloblastoma
Mari J Tokita, Shareef Nahas, Benjamin Briggs, Denise M Malicki, Jill P Mesirov, Iris Anne C Reyes, Lauge Farnaes, Michael L Levy, Stephen F Kingsmore, David Dimmock, John R Crawford, Robert J Wechsler-Reya
Cold Spring Harb Mol Case Stud. 2019 Oct 23;5(5):a004572. doi: 10.1101/mcs.a004572. Print 2019 Oct.
Genome sequencing was performed on matched normal and tumor tissue from a 6.5-yr-old boy with a diagnosis of recurrent medulloblastoma. A pathogenic heterozygous c.432+1G>A canonical splice donor site variant in GNAS was detected on analysis of blood DNA. Analysis of tumor DNA showed the same splice variant along with copy-neutral loss of heterozygosity on Chromosome 20 encompassing GNAS, consistent with predicted biallelic loss of GNAS in the tumor specimen. This case strengthens the evidence implicating GNAS as a tumor-suppressor gene in medulloblastoma and highlights a scenario in which therapeutics targeting the cAMP pathway may be of great utility.
PMID:31624069 | PMC:PMC6824258 | DOI:10.1101/mcs.a004572
October 19, 2019
Developmental phosphoproteomics identifies the kinase CK2 as a driver of Hedgehog signaling and a therapeutic target in medulloblastoma
Teresa Purzner, James Purzner, Taylor Buckstaff, Giorgio Cozza, Sharareh Gholamin, Jessica M Rusert, Tom A Hartl, John Sanders, Nicholas Conley, Xuecai Ge, Marc Langan, Vijay Ramaswamy, Lauren Ellis, Ulrike Litzenburger, Sara Bolin, Johanna Theruvath, Ryan Nitta, Lin Qi, Xiao-Nan Li, Gordon Li, Michael D Taylor, Robert J Wechsler-Reya, Lorenzo A Pinna, Yoon-Jae Cho, Margaret T Fuller, Joshua E Elias, Matthew P Scott
Sci Signal. 2018 Sep 11;11(547):eaau5147. doi: 10.1126/scisignal.aau5147.
A major limitation of targeted cancer therapy is the rapid emergence of drug resistance, which often arises through mutations at or downstream of the drug target or through intrinsic resistance of subpopulations of tumor cells. Medulloblastoma (MB), the most common pediatric brain tumor, is no exception, and MBs that are driven by sonic hedgehog (SHH) signaling are particularly aggressive and drug-resistant. To find new drug targets and therapeutics for MB that may be less susceptible to common resistance mechanisms, we used a developmental phosphoproteomics approach in murine granule neuron precursors (GNPs), the developmental cell of origin of MB. The protein kinase CK2 emerged as a driver of hundreds of phosphorylation events during the proliferative, MB-like stage of GNP growth, including the phosphorylation of three of the eight proteins commonly amplified in MB. CK2 was critical to the stabilization and activity of the transcription factor GLI2, a late downstream effector in SHH signaling. CK2 inhibitors decreased the viability of primary SHH-type MB patient cells in culture and blocked the growth of murine MB tumors that were resistant to currently available Hh inhibitors, thereby extending the survival of tumor-bearing mice. Because of structural interactions, one CK2 inhibitor (CX-4945) inhibited both wild-type and mutant CK2, indicating that this drug may avoid at least one common mode of acquired resistance. These findings suggest that CK2 inhibitors may be effective for treating patients with MB and show how phosphoproteomics may be used to gain insight into developmental biology and pathology.
PMID:30206138 | PMC:PMC6475502 | DOI:10.1126/scisignal.aau5147
September 13, 2018