Poster Presentation 37th Lorne Cancer Conference 2025

Exploring and targeting the androgen receptor pathway in glioblastoma (#204)

Sofia RE Mason 1 2 3 4 , Sylvia Chung 5 , Laveniya Satgunaseelan 1 6 , Cerys McCool 2 3 4 , Kimberley Alexander 1 6 7 , Ashraf Zaman 3 8 , Joseph Powell 3 8 , Bryan W Day 9 10 , Rachel Dear 3 4 , Hao-Wen Sim 1 2 3 4 11 , Jeff Holst 5 , Christine L Chaffer 2 3 4
  1. Chris O'Brien Lifehouse, Sydney, Australia
  2. St Vincent's Clinical School, UNSW, Sydney, NSW, Australia
  3. Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
  4. Kinghorn Cancer Centre, Darlinghurst, NSW, Australia
  5. School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, Australia
  6. Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
  7. School of Medical Sciences, University of Sydney, Sydney, NSW, Australia
  8. School of Clinical Medicine, UNSW Sydney, Sydney, NSW, Australia
  9. University of Queensland, Brisbane, Queensland, Australia
  10. QIMR Berghofer, Brisbane, Australia
  11. NHMRC Clinical Trials Centre, University of Sydney, Sydney, Australia

Background 

Glioblastoma is a deadly primary brain tumour that commonly expresses androgen receptors (AR). We investigated whether disrupting AR signalling with readily available blood-brain-barrier penetrant drugs could be a feasible therapeutic strategy to combine with standard therapy in glioblastoma. 

Methods 

Biobanked patient tumour samples and commercial tissue microarrays were stained by immunohistochemistry and scored for AR by a neuropathologist. AR positive models including conventional cell line U251 and patient derived xenograft RN1 were used for tumoursphere and proliferation analyses. Proliferation was measured by Alamar Blue and Incucyte. Expression of AR and ZEB1, a stemness marker, was determined by immunofluorescence and immunoblotting. RN1 was implanted orthotopically in nude mice to examine the effects of treatment with androgen inhibition with conventional therapies. 

Results 

Almost 80% of glioblastoma samples expressed AR by IHC (n=47/61). AR expression was seen in the nucleus and cytoplasm of tumour cells and correlated with increasing tumor grade (p<0.05). Positive AR staining was more common in men than women (86%; 37/43 versus 56%; 10/18) and of higher staining intensity (70% 2+ or 3+ in males, vs 8% 2+ or 3+ in females). Survival analysis of AR staining patterns and levels is underway. AR knockdown suppressed proliferation in vitro. Proliferation and tumoursphere formation were inhibited by enzalutamide, an AR antagonist, but more so by drugs that inhibit CYP17A1 and AR, abiraterone and seviteronel. Dihydrotestosterone increases ZEB1 expression; this is prevented by seviteronel. In the intracranial mouse model, seviteronel significantly improved survival compared to vehicle (n=12, 36.0 vs 27.5 days, p=0.03), and demonstrated reduced Ki67 expression in tumours at the endpoint (68.9% vs 85.0%, p<0.001). Combining seviteronel with temozolomide resulted in reduced growth by IVIS and an increase in tumour regression of 20% or more (50% compared to 25% with temozolomide monotherapy). However, seviteronel combined with temozolomide or radiotherapy did not extend survival compared to either treatment alone. 

 Conclusions 

AR is expressed in a majority of glioblastoma samples. Targeting AR with existing brain-penetrant drugs is being further explored in animal experiments, as is the assessment of AR as a predictive or prognostic biomarker in this deadly disease.