Brain Tumor SPORE ProjectsThe Northwestern Brain Tumor SPORE will take a team science approach, bringing together basic scientists, neuro-oncologists and neurosurgeons for interdisciplinary research designed to identify novel therapies for glioblastoma. The grant will fund four key research projects in this area, co-led by investigators with complementary expertise.
Neural Stem Cell Based Oncolytic Virotherapy of Malignant Glioma
Maciej S. Lesniak, MD (Project Leader)
Atique U. Ahmed, PhD (Co-Project Leader)
Irina V. Balyazsnikova, PhD (Co-Project Leader)
Roger Stupp, MD (Co-Project Leader)
James Chandler, MD (Investigator)
Sean Sachdev, MD (Investigator)
Benjamin Liu, MD (Investigator)
Oncolytic virotherapy (OV) is a novel modality of anti-cancer therapy, which consists of using genetically engineered conditionally replicating virus to target and destroy cancer cells. Such selectivity of viral replication is achieved by employing various strategies including transcriptional targeting where tumor selective expression is used to drive virus replication and capsid modifications that promotes tumor specific binding of the therapeutic virus. Our team has developed a dual targeted oncolytic virus, CARd-Survivin-pK7 (CARd-S-pk7), and extensively evaluated this virus for the treatment of malignant glioma. In preclinical research, CRAd-S-pk7 exhibits extensive anti-tumor activity in mice bearing intracranial human glioma xenografts, including the highly aggressive CD133+ glioma stem cell population, and cooperates with conventional anti-glioma chemo- and radiotherapy.
One of the major limitations of OV therapy has been poor intratumoral distribution. To overcome this problem our group has demonstrated that neural stem cells (NSCs) can be used as a virus producer to enhance viral delivery. This form of carrier cell based OV enhances viral distribution throughout the tumor, which results in a much more potent anti-tumor response than local delivery of OV alone. Based on this work, we are now translating this therapeutic approach to the clinical setting, and are in the midst of conducting a clinical trial to test cell based OV treatment in glioma patients. The immediate goal of this SPORE project is to evaluate the safety of NSCs-CRAd-S-pk7 as a therapeutic platform for patients with malignant glioma.
Our specific aims are
- Evaluate clinical responses in patients administered CRAd-S-pK7-loaded NSCs.
- Investigate immune response in patients administered NSCs carrying CRAd-S-pK7.
- Use imaging to assess cell distribution and tumor response to NSCs-CRAd-S-pK7 treatment.
Simultaneous Radiotherapy with PD-1 and IDO1 Blockade for Overcoming Immune Suppression in Glioblastoma
Derek A. Wainwright, PhD (Project Leader)
Rimas V. Lukas, MD (Co-Project Leader)
David James, PhD (Co-Project Leader)
Sean Sachdev, MD (Investigator)
Immunotherapy carries great promise for the treatment of several solid tumors, including malignant glioma. However, in order to have impact on immunotherapy treatment outcomes, a multimodal treatment approach is likely required. For GBM, a heterogeneous tumor characterized by local immunosuppression and an immune-privileged environment, a combination of radiotherapy with concomitant immunomodulation by an immune checkpoint inhibitor as well as an inhibitor of an immunosuppressive enzymatic activity could prove effective. We have used this approach in preclinical research and shown this triple therapy results in a durable survival benefit to mice with intracranial GBM. These preclinical findings will be translated to a clinical trial for patients with newly diagnosed GBM. The interpretation of treatment outcomes will be aided by the incorporation of a-[11C]-methyl-L-Trp (AMT)-PET imaging, which is a noninvasive method to quantifying IDO1 activity that is responsible for producing an immunosuppressive metabolite, and by a comprehensive immunmonitoring assay panel. In parallel, we will conduct further experiments with mice reconstituted with human immune function and inoculated with tumors of human origin (PDX), for testing additional therapeutics that can be incorporated in future clinical trials that are derivatives of the initial trial proposed here.
Our specific aims for this project are:
- Conduct a phase I/IIa study of RT with concurrent checkpoint (PD-1 mAb) and IDO1 enzyme inhibition in patients with newly diagnosed, MGMT-unmethylated GBM.
- Evaluate intratumoral IDO1 activity with AMT-PET in GBM patients receiving treatment with concurrent RT + PD-1 mAb + IDO1 inhibitor.
- Specific Aim 3: Characterize GBM and immune response to RT, PD-1 mAb and IDO1 enzyme inhibition.
Using RNAi-based Spherical Nucleic Acid (SNA) Nanoconjugates Targeting Bcl2L12 to Promote Therapy-Induced Apoptosis in Glioblastoma
Alexander Stegh, PhD (Project Lead)
Chad A. Mirkin, PhD (Co-Project Leader)
Priya Kumthekar, MD (Investigator)
Glioblastoma (GBM), the most aggressive and prevalent manifestation of malignant glioma, is characterized by resistance to extant therapeutic modalities, and exhibits a neurologically debilitating course culminating in death, most often within 14 months after diagnosis. The biggest challenge to improving GBM patient outcomes has been the identification and characterization of new drug targets and the development of drug delivery platforms to target previously undruggable genetic lesions. Restoration of p53 activity represents an attractive therapeutic strategy for the treatment of GBM, as ~65% of primary GBM patients express wildtype, but functionally suppressed p53. Amplification and overexpression of the atypical Bcl2 family protein Bcl2L12 (Bcl2-Like-12) compromises p53 function by blocking the transcriptional activity of p53. To inhibit Bcl2L12 function we have used novel RNAi-based nanoconjugates, termed Spherical Nucleic Acids (SNAs), to neutralize Bcl2L12 expression in established GBM. We have found that Bcl2L12-targeting SNAs (siBcl2L12-SNAs) are able to traverse cellular membranes including the blood-brain-barrier. We established that siBcl2L12-SNAs do not require the use of toxic auxiliary reagents and accumulate effectively in GBM tumor cells upon crossing the blood-brain/blood-tumor barrier in intracerebral GBM xenografts following systemic administration of the SNAs. SNAs exhibit stability in physiological environments, provoke robust intratumoral Bcl2L12 mRNA and protein knockdown resulting in p53 reactivation, and slow tumor growth in GBM patient derived xenograft (PDX) models. Here, we will further investigate the hypothesis that Bcl2L12 suppression by SNA treatment increases p53 tumor suppressor activity, slows GBM progression, and can be combined with conventional genotoxic therapies as well as with targeted therapeutics for improving GBM treatment outcomes.
We propose three specific aims:
- Determine siBcl2L12 treatment effect in patient-derived glioma-initiating cells (GICs) in vitro, and in PDX models in vivo, when used as monotherapy and in combination with radiation therapy (RT).
- Using both PDX models for newly diagnosed and recurrent tumor, together with syngeneic, immunocompetent mouse models, we will combine siBcl2L12 with cytotoxic and p53-activating chemotherapeutic drugs, i.e., the DNA alkylator temozolomide and the MDM2 inhibitor RG7388, respectively.
- Conduct a phase 0 clinical trial of siBcl2L12-SNAs, to determine SNA pharmacokinetics, biodistribution, and ability to downregulate GBM-associated Bcl2L12 mRNA and protein in patients.
Enhancing GBM Cytotoxic Therapy Through Inhibition of Key Autophagy Mediator ATG4B
Shi-Yuan Cheng, PhD (Project Leader)
Roger Stupp, MD (Co-Project Leader)
Leonidas C. Platanias, MD, PhD (Co-Project Leader)
Bo Hu, PhD (Co-Investigator)
Glioblastoma (GBM) is the most common and malignant primary brain tumor. Despite treatment consisting of surgical removal, radiation and chemotherapy, most patients with GBM die within 14 to 16 months after diagnosis, underscoring the urgent need for new therapies to combat this deadly disease. Autophagy is a conserved catabolic process that maintains homeostasis by regulating the energy balance of the cell. Cancer cells use autophagy to remove damaged organelles and aggregated proteins, and to recycle nutrients in high demand to support tumor growth. Radiochemotherapy (RT-TMZ) is the front-line treatment against GBM, but also activates the autophagic response in tumor cells, thus protecting the cells from undergoing apoptosis. Inhibition of mTOR signaling is a common target in cancer therapy. However, mTOR inhibition also induces autophagy in cancer cells. Consequently, there is substantial interest in inhibiting the protective mechanism of autophagy while treating cancer. Non-specific autophagy inhibitors like chloroquine (CQ) and hydroxy-CQ (HCQ) are being investigated in a large number of clinical trials. However, the lack of specificity of these compounds is associated with toxicity that limits their administration to patients. We discovered that ATG4B, an enzyme that converts LC3 to LC3-I/II, which is required for autophagy, is phosphorylated at serine residue 383 (p-S383) in glioma initiating cells (GICs). We found that ATG4B S383 phosphorylation increases GIC autophagic activity, and that intratumoral expression of p-S383 ATG4B correlates with poor prognosis in GBM patients. In contrast, knockdown of ATG4B, or expression of a non-phosphorylatable ATG4B mutant transgene (S383A), inhibits GSC autophagic response and tumorigenicity in the brains of athymic mice. Furthermore, pharmacologic inhibition of ATG4B, using compound NSC185058 that inhibits ATG4B enzymatic activity and GBM tumorigenicity, markedly enhances anti-tumor effects of RT, and increases the survival of animals with intracranially engrafted GICs. Additionally, NSC185058 also markedly enhances the GIC inhibitory effects of the a catalytic mTORC inhibitor AZD2014.
Based on these results we propose the following specific aims:
- Determine the anti-GBM effects of ATG4B inhibitor NSC185058, as monotherapy and in combination with RT-TMZ, through preclinical studies utilizing in vitro and in vivo models of GBM PDX.
- Investigate the therapeutic potential of combined ATG4B + mTOR inhibition with RT.
- Develop NSC185058 for use in patients, and test the inhibitor, both as a single agent and in combination with RT, in a clinical trial for treating patients with recurrent GBM.