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Thomas, A. A., Abrey, L. E., Terziev, R., Raizer, J., Martinez, N. L., Forsyth, P., et al. (2017). Multicenter phase II study of temozolomide and myeloablative chemotherapy with autologous stem cell transplant for newly diagnosed anaplastic oligodendroglioma. Neuro Oncol, 19(10), 1380–1390.
Abstract: Background: Anaplastic oligodendroglioma (AO) and anaplastic oligoastrocytoma (AOA) are chemotherapy-sensitive tumors with prolonged survival after radiochemotherapy. We report a prospective trial using induction temozolomide (TMZ) followed by myeloablative high-dose chemotherapy (HDC) with autologous stem-cell transplant (ASCT) as a potential strategy to defer radiotherapy. Methods: Patients with AO/AOA received 6 cycles of TMZ (200 mg/m2 x 5/28 day). Responding patients were eligible for HDC (thiotepa 250 mg/m2/day x 3 days, then busulfan 3.2 mg/kg/day x 3 days), followed by ASCT. Genomic characterization was performed using next-generation sequencing. Results: Forty-one patients were enrolled; 85% had 1p/19q codeleted tumors. After induction, 26 patients were eligible for HDC-ASCT and 21 agreed to proceed. There were no unexpected adverse events or toxic deaths. After median follow-up of 66 months, 2-year progression-free survival (PFS) for transplanted patients was 86%, 5-year PFS 60%, and no patient has died. Among all 1p/19q codeleted patients (N = 33), 5-year PFS was 50% and 5-year overall survival (OS) 93%, with median time to radiotherapy not reached. Next-generation sequencing disclosed typical oligodendroglioma-related mutations, including IDH1, TERT, CIC, and FUBP1 mutations in 1p/19q codeleted patients, and glioblastoma-like signatures in 1p/19q intact patients. Aside from IDH1, potentially oncogenic/actionable mutations were variable, depicting wide molecular heterogeneity within oligodendroglial tumors. Conclusions: TMZ followed by HDC-ASCT can be safely administered to patients with newly diagnosed 1p/19q codeleted AO. This strategy was associated with promising PFS and OS, suggesting that a chemotherapy-based approach may delay the need for radiotherapy and radiation-related toxicities. Raw data for further genomic and meta-analyses are publicly available at http://cbioportal.org/study?id=odgmsk2017, accessed 6 January 2017. Clinicaltrials.gov registry: NCT00588523.
Keywords: 1p/19q codeletion; anaplastic oligodendroglioma; autologous stem cell transplant; temozolomide
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Shahar, T., Rozovski, U., Hess, K. R., Hossain, A., Gumin, J., Gao, F., et al. (2017). Percentage of mesenchymal stem cells in high-grade glioma tumor samples correlates with patient survival. Neuro Oncol, 19(5), 660–668.
Abstract: Background: Human mesenchymal stem cells (hMSCs) have been shown to reside as stromal cells in human gliomas as glioma-associated hMSCs (GA-hMSCs), but their biological role remains unclear. Because recent evidence indicates that GA-hMSCs drive tumor cell proliferation and stemness, we hypothesized that a higher percentage of GA-hMSCs in tumors predicts poor patient prognosis. Method: We determined the percentage of cells coexpressing GA-hMSC markers CD105+/CD73+/CD90+ from patients with newly diagnosed high-grade glioma and analyzed the association between this percentage and overall survival (OS) in 3 independent cohorts: fresh surgical glioblastoma specimens (cohort 1, N = 9), cultured tumor specimens at passage 3 (cohort 2, N = 28), and The Cancer Genome Atlas (TCGA) database. Results: In all cohorts, patient OS correlated with the percentages of GA-hMSCs in tumors. For cohort 1, the median OS of patients with tumors with a low percentage of triple-positive cells was 46 months, and for tumors with a high percentage of triple-positive cells, it was 12 months (hazard ratio [HR] = 0.24; 95% CI: 0.02-0.5, P = .02). For cohort 2, the median OS of patients with tumors with a low percentage of GA-hMSCs was 66 months, and for tumors with a high percentage, it was 11 months (HR = 0.38; 95% CI: 0.13-0.9, P = .04). In the database of TCGA, the median OS times in patients with high and low coexpression levels of CD105/CD73/CD90 were 8.4 months and 13.1 months (HR = 0.4; 95% CI: 0.1-0.88; P = .04), respectively. Conclusions: The percentage of GA-MSCs inversely correlates with OS, suggesting a role for GA-MSCs in promoting aggressive behavior of gliomas.
Keywords: *glioblastoma; *mesenchymal stem cells; *microenvironment; *prognosis
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D'Alessandris, Q. G., Biffoni, M., Martini, M., Runci, D., Buccarelli, M., Cenci, T., et al. (2017). The clinical value of patient-derived glioblastoma tumorspheres in predicting treatment response. Neuro Oncol, 19(8), 1097–1108.
Abstract: Background: Advances from glioma stemlike cell (GSC) research, though increasing our knowledge of glioblastoma (GBM) biology, do not influence clinical decisions yet. We explored the translational power of GSC-enriched cultures from patient-derived tumorspheres (TS) in predicting treatment response. Methods: The relationship between TS growth and clinical outcome was investigated in 52 GBMs treated with surgical resection followed by radiotherapy and temozolomide (TMZ). The effect on TS of radiation (6 to 60 Gy) and of TMZ (3.9 muM to 1 mM) was related with patients' survival. Results: Generation of TS was an independent factor for poor overall survival (OS) and poor progression-free survival (PFS) (P < .0001 and P = .0010, respectively). Growth rate and clonogenicity of TS predicted poor OS. In general, TS were highly resistant to both radiation and TMZ. Resistance to TMZ was stronger in TS with high clonogenicity and fast growth (P < .02). Shorter PFS was associated with radiation LD50 (lethal dose required to kill 50% of TS cells) >12 Gy of matched TS (P = .0484). A direct relationship was found between sensitivity of TS to TMZ and patients' survival (P = .0167 and P = .0436 for OS and PFS, respectively). Importantly, values for TMZ half-maximal inhibitory concentration <50 muM, which are in the range of plasma levels achieved in vivo, identified cases with longer OS and PFS (P = .0020 and P = .0016, respectively). Conclusions: Analysis of TS holds translational relevance by predicting the response of parent tumors to radiation and, particularly, to TMZ. Dissecting the clonogenic population from proliferating progeny in TS can guide therapeutic strategies to a more effective drug selection and treatment duration.
Keywords: cancer stem cells; glioblastoma; radiotherapy; temozolomide; treatment outcome
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Goffart, N., Lombard, A., Lallemand, F., Kroonen, J., Nassen, J., Di Valentin, E., et al. (2017). CXCL12 mediates glioblastoma resistance to radiotherapy in the subventricular zone. Neuro Oncol, 19(1), 66–77.
Abstract: BACKGROUND: Patients with glioblastoma (GBM) have an overall median survival of 15 months despite multimodal therapy. These catastrophic survival rates are to be correlated to systematic relapses that might arise from remaining glioblastoma stem cells (GSCs) left behind after surgery. In this line, it has recently been demonstrated that GSCs are able to escape the tumor mass and preferentially colonize the adult subventricular zone (SVZ). At a distance from the initial tumor site, these GSCs might therefore represent a high-quality model of clinical resilience to therapy and cancer relapses as they specifically retain tumor-initiating abilities. METHOD: While relying on recent findings that have validated the existence of GSCs in the human SVZ, we questioned the role of the SVZ niche as a potential GSC reservoir involved in therapeutic failure. RESULTS: Our results demonstrate that (i) GSCs located in the SVZ are specifically resistant to radiation in vivo, (ii) these cells display enhanced mesenchymal roots that are known to be associated with cancer radioresistance, (iii) these mesenchymal traits are specifically upregulated by CXCL12 (stromal cell-derived factor-1) both in vitro and in the SVZ environment, (iv) the amount of SVZ-released CXCL12 mediates GBM resistance to radiation in vitro, and (v) interferes with the CXCL12/CXCR4 signalling system, allowing weakening of the tumor mesenchymal roots and radiosensitizing SVZ-nested GBM cells. CONCLUSION: Together, these data provide evidence on how the adult SVZ environment, through the release of CXCL12, supports GBM therapeutic failure and potential tumor relapse.
Keywords: Animals; Brain Neoplasms/metabolism/*pathology/radiotherapy; Chemokine CXCL12/*metabolism; Cranial Irradiation/*adverse effects; Gamma Rays/adverse effects; Glioblastoma/metabolism/*pathology/radiotherapy; Humans; Lateral Ventricles/metabolism/*pathology/radiation effects; Mice; Mice, Nude; Neoplastic Stem Cells/metabolism/*pathology/radiation effects; *Radiation Tolerance; Signal Transduction/radiation effects; Tumor Cells, Cultured; Cxcl12; glioblastoma; mesenchymal activation; radioresistance; subventricular zone
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Liu, Y., Shen, Y., Sun, T., & Yang, W. (2017). Mechanisms regulating radiosensitivity of glioma stem cells. Neoplasma, 64(5), 655–665.
Abstract: Malignant glioblastoma (GBM) has become a very common and difficult brain tumor given its low cure rate and high recurrence rate. GBMs are resistant to treatments because glioma stem cells (GSCs)/glioma-initiating cells (GICs), a specific subpopulation of GBM, possess properties of tumor stem cells, such as unlimited proficiency, self-renewal, differentiation and resistance to chemotherapy and radiotherapy, and exhibit a very strong DNA repair capability. Radiotherapy has become a preponderant treatment, and researchers have found many significant tumor microenvironmental factors and valuable signaling pathways regulating the GSC radioresistance, including NOTCH, Wnt/beta-catenin, Hedgehog, STAT3, and PI3K/AKT/mTOR. Therefore, we seek to boost GSC radiosensitivity through activating or inactivating pathways alone or together to eliminate the likely source of glioma and prolong survival of patients.
Keywords: glioma stem cells; radiosensitivity signaling pathways.
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