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OBJECTIVE Glioblastoma has been known to be resistant to chemotherapy and radiation, whereas the underlying mechanisms of resistance have not been fully elucidated. The authors studied the role of the transcription factor ZEB1 (zinc finger E-box-binding homeobox 1 protein), which is associated with epithelial-mesenchymal transition (EMT) and is central to the stemness of glioblastoma, to determine its role in therapeutic resistance to radiation and chemotherapy. The authors previously demonstrated that ZEB1 is deleted in a majority of glioblastomas. METHODS The authors explored resistance to therapy in the context of ZEB1 loss and overexpression in glioma stem cells (GSCs) and in patient data. RESULTS Patients with ZEB1 loss had a shorter survival time than patients with wild-type ZEB1 in both the high- and low-MGMT groups. Consistent with the clinical data, mice implanted with ZEB1 knockdown GSCs showed shortened survival compared with mice inoculated with nonsilencing control (NS) short-hairpin RNA (shRNA) GSC glioblastoma. ZEB1-deleted GSCs demonstrated increased tumorigenicity with regard to proliferation and invasion. Importantly, GSCs that lose ZEB1 expression develop enhanced resistance to chemotherapy, radiotherapy, and combined chemoradiation. ZEB1 loss may lead to increased HER3 expression through the HER3/Akt pathway associated with this chemoresistance. Conversely, overexpression of ZEB1 in GSCs that are ZEB1 null leads to increased sensitivity to chemoradiation. CONCLUSIONS The study results indicate that ZEB1 loss in cancer stem cells confers resistance to chemoradiation and uncovers a potentially targetable cell surface receptor in these resistant cells.

Figures S6 and S7. Localization of labeled nanobioconjugates in tumors and biodistribution in brain. The nano drug is seen in the tumor parenchyma outside of blood vessels (S6) and preferentially accumulates in the tumor (peaks at 6 hr post-injection) as compared to contralateral brain tissue (S7)

Figures S2, S3 and S4. Morphometric analysis of laminin-411 β1 chain (S2) and cancer stem cell markers (Notch-1, Notch-3, CD133, Nestin, and c-Myc; S3 and S4) on frozen sections of patient brain tumors. The expression of all markers significantly correlated with glioma grade

Video schematically shows the mechanism of glioblastoma treatment by laminin-411 inhibiting nanobioconjugate

Figure S5. Binding of the nanobioconjugates to U87MG studied by flow cytometry is inhibited by human soluble TfR. This shows that the chimeric anti-human TfR antibody as part of nanobioconjugate fully retained its activity

Purpose:Glioblastoma (GBM) is a heterogeneous malignancy with multiple subpopulations of cancer cells present within any tumor. We present the results of a phase I clinical trial using an autologous dendritic cell (DC) vaccine pulsed with lysate derived from a GBM stem-like cell line.Patients and Methods:Patients with newly diagnosed and recurrent GBM were enrolled as separate cohorts. Eligibility criteria included a qualifying surgical resection or minimal tumor size, ≤ 4-mg dexamethasone daily dose, and Karnofsky score ≥70. Vaccine treatment consisted of two phases: an induction phase with vaccine given weekly for 4 weeks, and a maintenance phase with vaccines administered every 8 weeks until depletion of supply or disease progression. Patients with newly diagnosed GBM also received standard-of-care radiation and temozolomide. The primary objective for this open-label, single-institution trial was to assess the safety and tolerability of the autologous DC vaccine.Results:For the 11 patients with newly diagnosed GBM, median progression-free survival (PFS) was 8.75 months, and median overall survival was 20.36 months. For the 25 patients with recurrent GBM, median PFS was 3.23 months, 6-month PFS was 24%, and median survival was 11.97 months. A subset of patients developed a cytotoxic T-cell response as determined by an IFNγ ELISpot assay.Conclusions:In this trial, treatment of newly diagnosed and recurrent GBM with autologous DC vaccine pulsed with lysate derived from an allogeneic stem-like cell line was safe and well tolerated. Clinical outcomes add to the body of evidence suggesting that immunotherapy plays a role in the treatment of GBM.

Supplementary Data from A Phase I Study of Autologous Dendritic Cell Vaccine Pulsed with Allogeneic Stem-like Cell Line Lysate in Patients with Newly Diagnosed or Recurrent Glioblastoma

Figure S10. Expression of Notch-1 and its ligand Jagged1 is significantly decreased in patient-derived glioblastoma cell lines with laminin-411 disruption by CRISPR/Cas9

Figures S8 and S9. Quantification of expression of laminin-411 β1 chain, its binding β1 integrin, Notch family members and other stem cell markers after nanobioconjugate treatment. All markers were significantly suppressed in treated tumors.

Tables S1, S2 and S3, and Figure S1. List of used antibodies (Table S1), and immunohistochemical expression of laminin-411 and laminin-421 in human gliomas of various grades (Tables S2 and S3). Expression of laminin-411 vs. laminin-421 increases with glioma grade and in GBMs it correlates with shorter patient survival and faster tumor recurrence (Figure S1)

Supplementary Figure from A Phase I Study of Autologous Dendritic Cell Vaccine Pulsed with Allogeneic Stem-like Cell Line Lysate in Patients with Newly Diagnosed or Recurrent Glioblastoma

Table S4. Physico-chemical characterization of used control and treatment nanobioconjugates