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.

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.

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.