Poster Presentation Hunter Cell Biology Meeting 2022

DRD2/DRD3 antagonism by ONC201 induces immunomodulatory effects in diffuse midline glioma (#92)

Mika L Persson 1 2 , Evangeline R Jackson 1 2 , Ryan J Duchatel 1 2 , Liesl Bramberger 3 , Holly McEwen 1 2 , Padriac S Kearney 1 2 , Alicia M Douglas 1 2 , Martin R Larsen 4 , Nicholas A Vitanza 5 6 , Pouya Faridi 3 , Jeff Holst 7 , Esther Hulleman 8 , Jasper Van der Lugt 8 , Sabine Mueller 9 10 , Hubert Hondermarck 11 , Jay Horvat 12 , Brett Nixon 13 14 , Matthew D Dun 1 2
  1. Cancer Signalling Research Group, School of Biomedical Sciences & Pharmacy, College of Health, University of Newcastle, Callaghan, NSW, Australia
  2. Precision Medicine Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
  3. Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, VIC, Australia
  4. Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
  5. Ben Towne Center for Childhood Cancer Research, Seattle Children’s Research Institute, Seattle, WA, USA
  6. Division of Pediatric Hematology/Oncology, Department of Pediatrics, Seattle Children’s Hospital, Seattle, WA, USA
  7. Translational Cancer Metabolism Laboratory, School of Medical Sciences and Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia
  8. Princess Máxima Center for Pediatric Oncology, Utretch, The Neatherlands
  9. Department of Oncology, Children’s Research Center, University Children’s Hospital Zurich, Zurich, Switzerland
  10. Department of Pediatrics and Neurosurgery, University of California, San Francisco, San Francisco, CA, USA
  11. Cancer Neurobiology Group, School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
  12. Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute and University of Newcastle, Newcastle, NSW, Australia
  13. Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
  14. Hunter Medical Research Institute, New Lambton Heights, NSW, Australia

Background

Patients diagnosed with diffuse midline glioma (DMG) have an overall survival of 9-11 months, with radiotherapy the only approved treatment. DMG is characterised by a cold tumour microenvironment (TME), with few tumour infiltrating lymphocytes (TILs) and inflammatory factors, likely explaining the failure of immune checkpoint inhibition (ICI). The cause of the cold TME remains uncertain, as the tumour does not harbour known immunosuppressive features. The cold TME seen in glioblastoma can be explained by systemic T cell lymphopenia.1 In glioblastoma, T cells are sequestered in the bone marrow due to loss of Sphingosine-1-phosphate receptor 1 (S1PR1) expression. S1PR1 internalization is driven by recruitment of β-arrestin, which is activated by Dopamine receptor D2 and D3 (DRD2, DRD3) signalling. ONC201 is a potent DRD2/DRD3 antagonist, showing some clinical efficacy as monotherapy for patients with DMG in the upfront setting. Work from our laboratory has informed the recently commenced DMG clinical trial NCT05009992, investigating radiotherapy, and ONC201 used in combination with the PI3K inhibitor paxalisib as maintenance. Importantly, PIK3CA knockout promotes expression of the major histocompatibility complex I (MHC I) increasing an adaptive immune response, with PI3K inhibitors working synergistically with ICIs highlighting the role of PI3K inhibition in immunomodulation.2,3

Aims

To determine whether T cell lymphopenia occurs in DMG patients/models and whether DRD2/DRD3 antagonism using ONC201 + paxalisib can warm the cold TME, sensitising DMG to immunotherapies.

Methods

Proteomic profiling was performed using DMG patient derived cells +/- ONC201. Western blot and immunohistochemistry analysis was performed on tumours from SU-DIPG-VI patient derived xenograft (PDX) NSG mouse models treated +/- ONC201 and in combination with paxalisib.

Results

ONC201 treatment increased the expression of members of the MHC I antigen presentation pathway, including B2M and HLA-A, illuminating DMG to the immune system. Increased B2M expression following ONC201 was confirmed in DMG-PDX models, also revealing further increase of B2M expression when combined with paxalisib. For the first time, we uncover a therapeutic means to promote recruitment of TILs through the combination of ONC201 and paxalisib. Preliminary mechanistic studies suggest that ONC201 and paxalisib increase MHC I activity, decrease dopamine signalling and promote the expression of EMILIN-3 a potent antagonist of immunosuppressive TGF-β, known to inhibit B2M expression.

Conclusion

Antagonism of DRD2/DRD3 with ONC201 primes DMG for an immune response, amplified with paxalisib. Work continues to understand T cell lymphopenia in DMG and whether DRD2/DRD3 antagonism can reverse the phenotype and sensitize DMG to immunotherapies.

  1. Chongsathidkiet P, et al. Sequestration of T-cells in bone marrow in the setting of glioblastoma and other intracranial tumors. Nat Med. 2018 September; 24(9): 1459–1468. doi:10.1038/s41591-018-0135-2.
  2. Sivaram N, et al. Tumor-intrinsic PIK3CA represses immunogenicity in a model of pancreatic cancer. J Clin Invest. 2019: 129(8):3264-3276. doi: 10.1172/JCI123540
  3. Borcoman E, et al. Inhibition of PI3K pathway increases immune infiltrate in muscle-invasive bladder cancer. Oncoimmunology. 2019; 8(5):e1581556. doi:10.1080/2162402X.2019.1581556