HGG-32. ONC201 AND ONC206 TARGET TUMOR CELL METABOLISM IN PEDIATRIC DIFFUSE MIDLINE GLIOMA PRECLINICAL MODELS

Diffuse midline gliomas (DMGs) remain incurable cancers and new treatments are urgently needed. One promising new therapeutic avenue for these cancers is targeting of metabolic vulnerabilities including a heightened dependence on mitochondrial metabolism. We and others have shown that the oral, brain-penetrant imipridone drugs ONC201 and ONC206 target mitochondrial metabolism in cancer cells. In particular, ONC201 and ONC206 hyper-activate the mitochondrial protease ClpP, impair mitochondrial oxidative phosphorylation (OXPHOS), activate the integrated stress response (ISR) signaling pathway, and induce apoptosis in DMG preclinical models. We validated ClpP as a key target of ONC206 by showing that CRISPR/Cas9-mediated CLPP knockout significantly decreased ONC206 sensitivity in DMG cells. We further showed that imipridone-mediated ClpP activation resulted in significant degradation of the chaperone protein ClpX. Moreover, ONC201 and ONC206 treatment inhibited mitochondrial respiration, decreased mitochondrial membrane potential and triggered extensive mitochondrial structural damage, including disintegration of mitochondrial cristae. Time-course RNA sequencing of five DMG cell lines treated with ONC201 and ONC206, alone or in combination, revealed robust ATF4 and CHOP upregulation, indicating potent activation of ISR signaling. Notably, ATF4/CHOP upregulation was strongest in ONC201/6 combination-treated cells, indicating synergy between the two drugs. We further explored drug combinations by testing ONC201 together with ONC206, Panobinostat, JQ1, and Osimertinib to identify synergistic combination treatments. The strongest synergistic effect was found over a broad IC50 range for ONC201 and ONC206. Finally, we showed that ONC201 and ONC206 significantly prolonged survival of mice bearing brainstem DIPG xenografts. Ongoing studies include assessment of the in vivo efficacy of ONC201 and ONC206 across different CNS tumor models, as well as investigation and validation of clinically relevant biomarkers of response to treatment. In summary, our preclinical data strongly support the utility of the mitochondrial targeting agents ONC201 and ONC206 for the treatment of DMG and other malignant brain tumors.

Metabolic Targeting of Cancer Stem Cells

Most human tumors possess a high heterogeneity resulting from both clonal evolution and cell differentiation program. The process of cell differentiation is initiated from a population of cancer stem cells (CSCs), which are enriched in tumor‐regenerating and tumor‐propagating activities and responsible for tumor maintenance and regrowth after treatment. Intrinsic resistance to conventional therapies, as well as a high degree of phenotypic plasticity, makes CSCs hard-to-target tumor cell population. Reprogramming of CSC metabolic pathways plays an essential role in tumor progression and metastatic spread. Many of these pathways confer cell adaptation to the microenvironmental stresses, including a shortage of nutrients and anti-cancer therapies. A better understanding of CSC metabolic dependences as well as metabolic communication between CSCs and the tumor microenvironment are of utmost importance for efficient cancer treatment. In this mini-review, we discuss the general characteristics of CSC metabolism and potential metabolic targeting of CSC populations as a potent strategy to enhance the efficacy of conventional treatment approaches.

Folic Acid Immobilized Ferrimagnetic DP-Bioglass to Target Tumor Cell for Cancer Hyperthermia Treatment

DP-bioglass is one of biodegradable glasses, which can be used as bioactive material in soft tissue and bone. It was often used in orthopedy and plastic surgery. Recently, bioglass was also used as a carrier for drug and gene delivery systems. Additionally, ferrimagnetic DP-bioglass can be potential candidates for magnetic induction hyperthermia, by using a magnetic field. The aim of this work is the preparation and characterization of surface-modified ferrimagnetic DP-bioglass. First DP-bioglass has to be surface-modified with polyethylene glycol (PEG) and folic acid (FA) to improve its intracellular uptake and ability to target specific cells. PEG-FA complex was synthesized using carbodiimide (DCC) to link PEG with FA. Then PEG-FA complex were immobilized on the surface of DP-bioglass by using amino-silane (AEAPS) as a coupling agent. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), and thermogravimetric analysis (TGA) was used to demonstrate this immobilization process. In biological study showed that immobilized ferromagnetic DP-bioglass with PEG-FA was non-cytotoxicity and significantly enhanced the intracellular uptake of DP-bioglass by target cells.

Ti (WT31)-negative, CD3-positive, large granular lymphocyte leukemia with nonspecific cytotoxicity

A case of WT31-, CD3+ large granular lymphocyte leukemia is reported. On surface marker analysis, the proliferating cells were found to be CD3+4–8–16+ and WT31-. By two-color immunofluorescence staining, CD3+4- 8- cells were found to be WT31-, and a small population of WT31+ cells expressed either CD4 or CD8. WT31-, CD3+ cells were also identified in a bulk culture of lymphocytes expanded in vitro. Because WT31 monoclonal antibody (MoAb) reacts with the nonpolymorphic epitope of the disulfide-linked heterodimer of the T cell antigen receptor (Ti), the absence of the WT31-reactive Ti determinant may represent an expression of different CD3-associated polypeptides. The rearrangement of the Ti-beta and Ti-gamma genes but not the immunoglobulin gene was demonstrated, and the single pattern of rearrangement indicated the monoclonal origin of the lymphocytes. When the lymphocytes were assayed for their cytotoxicity against K562, MOLT-4, Daudi, and Raji tumor cell lines, a broad spectrum of cytotoxicity for these tumor cells was observed, and the lymphocytes also exhibited antibody- and lectin- dependent cellular cytotoxicity and lymphokine-activated killer activity. Treatment with anti-CD2 and anti-CD3 MoAbs inhibited their nonspecific cytotoxicity. The anti-CD3-mediated inhibition of nonspecific cytotoxicity suggested that an as yet unidentified Ti, present in association with the CD3 molecule on these lymphocytes, serves as a specific receptor for target tumor cell recognition.

Ti (WT31)-negative, CD3-positive, large granular lymphocyte leukemia with nonspecific cytotoxicity

A case of WT31-, CD3+ large granular lymphocyte leukemia is reported. On surface marker analysis, the proliferating cells were found to be CD3+4–8–16+ and WT31-. By two-color immunofluorescence staining, CD3+4- 8- cells were found to be WT31-, and a small population of WT31+ cells expressed either CD4 or CD8. WT31-, CD3+ cells were also identified in a bulk culture of lymphocytes expanded in vitro. Because WT31 monoclonal antibody (MoAb) reacts with the nonpolymorphic epitope of the disulfide-linked heterodimer of the T cell antigen receptor (Ti), the absence of the WT31-reactive Ti determinant may represent an expression of different CD3-associated polypeptides. The rearrangement of the Ti-beta and Ti-gamma genes but not the immunoglobulin gene was demonstrated, and the single pattern of rearrangement indicated the monoclonal origin of the lymphocytes. When the lymphocytes were assayed for their cytotoxicity against K562, MOLT-4, Daudi, and Raji tumor cell lines, a broad spectrum of cytotoxicity for these tumor cells was observed, and the lymphocytes also exhibited antibody- and lectin- dependent cellular cytotoxicity and lymphokine-activated killer activity. Treatment with anti-CD2 and anti-CD3 MoAbs inhibited their nonspecific cytotoxicity. The anti-CD3-mediated inhibition of nonspecific cytotoxicity suggested that an as yet unidentified Ti, present in association with the CD3 molecule on these lymphocytes, serves as a specific receptor for target tumor cell recognition.