Oral Presentation Hunter Cell Biology Meeting 2022

Preclinical efficacy results combining ONC201 and paxalisib for the treatment of patients with diffuse intrinsic pontine glioma (DIPG) (#37)

Evangeline R Jackson 1 2 , Ryan J Duchatel 1 2 , Mika L Persson 1 2 , Abdul Mannan 1 2 , Sridevi Yadavilli 3 4 , Sarah Parackal 5 6 , Shaye Game 5 6 , Wai Chin Chong 5 6 , W. Samantha N. Jayasekara 5 6 , Marion Le Grand 7 , Padraic S Kearney 1 2 , Alicia M Douglas 1 2 , Izac J Findlay 1 2 , Dilana Staudt 1 2 , Zacary P Germon 1 2 , Adjanie Patabendige 8 , David A Skerrett-Byrne 9 10 , Brett Nixon 9 10 , Nathan D Smith 11 , Bryan Day 12 , Neevika Manoharan 13 , Geoff B McCowage 14 , Ron Firestein 15 , Frank Alvaro 2 16 , Sebastian M Waszak 17 18 , Martin R Larsen 19 , Yolanda Colino-Sanguino 20 21 , Fatima Valdes-Mora 20 21 , Andria Rakotomalala 22 23 , Samuel Meignan 22 23 , Eddy Pasquier 7 24 , Nicholas Andre 25 26 , Esther Hulleman 27 , David D Eisenstat 28 29 , Nicholas A Vitanza 30 31 , Javad Nazarian 3 32 33 , Carl Koschmann 34 , Sabine Mueller 32 35 , Jason E Cain 5 6 , Matthew D Dun 1 2
  1. Cancer Signalling Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, NSW, Australia
  2. Precision Medicine Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
  3. Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
  4. Brain Tumor Institute, Children’s National Hospital, Washington, DC, USA
  5. Hudson Institute of Medical Research, Clayton, VIC, Australia
  6. Department of Molecular and Translational Science, Monash University, Clayton, VIC, Australia
  7. Centre de Recherche en Cancérologie de Marseille, Aix-Marseille Université, Inserm, CNRS, Institut Paoli Calmettes, Marseille, France
  8. Brain Barriers Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, NSw, Australia
  9. School of Environmental and Life Sciences, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW, Australia
  10. Infertility and Reproduction Research Program, Hunter Medical Institute, New Lambton Heights, NSW, Australia
  11. Analytical and Biomolecular Research Facility Advanced Mass Spectrometry Unit, University of Newcastle, Callaghan, NSW, Australia
  12. QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
  13. Department of Paediatric Oncology, Sydney Children’s Hospital, Randwick, NSW, Australia
  14. Department of Oncology, The Children's Hospital at Westmead, Westmead, NSW, Australia
  15. Cancer Centre, Hudson Institute of Medical Research, Clayton, VIC, Australia
  16. John Hunter Children’s Hospital, New Lambton Heights, NSW, Australia
  17. Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo, Norway
  18. Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
  19. Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
  20. Cancer Epigenetics Biology and Therapeutics, Precision Medicine Theme, Children’s Cancer Institute, Sydney, NSW, Australia
  21. School of Children and Women Health, University of NSW, Sydney, NSW, Australia
  22. Tumorigenesis and Resistance to Treatment Unit, Centre Oscar Lambret, Lille, France
  23. University of Lille, CNRS, Inserm, CHU Lille, UMR9020-U1277, CANTHER, Cancer Heterogeneity Plasticity and Resistance to Therapies, Lille, France
  24. Metronomics Global Health Initiative, Marseille, France
  25. Department of Pediatric Oncology, La Timone Children’s Hospital, AP-HM, Marseille, France
  26. SMARTc Unit, Centre de Recherche en Cancérologie de Marseille, Inserm, Aix Marseille University, Marseille, France
  27. Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
  28. Children’s Cancer Centre, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
  29. Neuro-Oncology Laboratory, Murdoch Children’s Research Institute, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
  30. Ben Towne Center for Childhood Cancer Research, Seattle Children’s Research Institute, Seattle, WA, USA
  31. Division of Pediatric Hematology/Oncology, Department of Pediatrics, Seattle Children’s Hospital, Seattle, WA, USA
  32. Department of Oncology, Children’s Research Center, University Children’s Hospital Zürich, Zurich, Switzerland
  33. The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
  34. Division of Pediatric Hematology/Oncology, Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA
  35. Department of Neurology, Neurosurgery and Pediatric, University of California, San Francisco, San Francisco, CA, USA

Background: Diffuse midline gliomas (DMG), including those located in the brainstem (diffuse intrinsic pontine glioma – DIPG) comprise almost half of all paediatric high grade gliomas and are considered the most lethal of all children’s cancers. DIPG harbours a median overall survival of 9-11-months, where the only approved treatment is palliative radiotherapy. Preliminary clinical efficacy for the small molecule brain-penetrant drug ONC201 shows an emerging survival benefit in early-stage clinical trials (NCT03416530), however, many patients do not respond, and all patients become resistant.

Aim: To uncover the mechanisms by which DIPG cell lines escape cell death following ONC201 treatment, and use these data to design strategies to improve response.

Methods: Initial testing revealed 10/13 patient-derived DIPG cell lines responded to ONC201. To uncover mechanisms of resistance, we performed quantitative proteomics on the H3.3K27M TP53-mutant ONC201 resistant line, SU-DIPG-VI, +/-ONC201 grown under hypoxic and normoxic conditions.

Results: Pathway analysis of proteomic profiling results identified mitochondrial degradation as the most enriched biological process. ONC201 is known to be a potent agonist of the mitochondrial protease CLPP, hence proteolysis and degradation of electron transport chain proteins including SDHA, and TCA cycle proteins including IDH3, were seen following 24 h treatment. The loss of mitochondrial integrity, including TCA cycle activity, promoted metabolic alterations to the epigenome, including increased trimethylation of H3K4 and H3K27. Therapeutic rescue was underpinned by redox-activated PI3K/AKT signalling, prompting the use of the blood-brain barrier permeable, clinically relevant PI3K/AKT inhibitor, paxalisib (NCT0396355). The combination with ONC201 was synergistically cytotoxic in both ONC201 sensitive and resistant DIPG cell lines, however, not in normal control peripheral blood mononuclear cells. Synergism was also seen in vivo using the SU-DIPG-VI-patient derived xenograft mouse model (p=0.0043). This combination was provided under compassionate access for two DIPG patients. Case 1, 6-year-old DIPG patient 6-weeks post-radiotherapy received the combination of ONC201 (15 mg/kg weekly) and paxalisib (27mg/m2 daily). Patient continues to receive the combination, 15-months after diagnosis and has experienced an almost complete regression of the primary tumour. Case 2, 16-year-old DIPG patient, commenced the combination following re-irradiation, 18-months post-diagnosis. Patient experienced a 34% reduction in tumour volume, with marked resolution of neurological symptoms, but unfortunately passed away from pneumocystis pneumonia 23-months after diagnosis.

Conclusions: Our preclinical and case study results underpin the recently commenced phase II clinical trial (NCT05009992), testing the combination of ONC201 and paxalisib immediately post-radiotherapy, or for patients in disease progression, immediately post re-irradiation.