Advancing Glioblastoma Research with Immuno-PET Imaging

Sep 11, 2023, 14:43 PM by Arnaud Legrand

Glioblastoma, a highly malignant brain tumour, continues to present significant clinical challenges. With limited treatment options and poor prognoses, novel approaches to addressing glioblastoma are urgently needed. One promising avenue in cancer therapy is immunotherapy, particularly immune checkpoint inhibitors (ICPIs) such as nivolumab and pembrolizumab. However, the application of ICPIs in glioblastoma has been met with limited success. This challenge is attributed to glioblastoma's immune-suppressive microenvironment, characterised by a lack of immune cells and the presence of immunosuppressive factors. Nevertheless, a proportion of tumours have elevated levels of immune checkpoint protein such as programmed death ligand-1 (PD-L1) and, in theory, could respond to ICPIs. This is why accurately measuring PD-L1 expression within GBM is essential to assess whether immunotherapy can be beneficial to patients. But it has proven to be a complex task. A new study led by Dr Gabriela Kramer-Marek at the ICR and Gitanjali Sharma, one of our PhD Student, hints at a new solution to this problem.

Presently, PD-L1 assessment relies on immunohistochemistry (IHC) conducted on postoperative samples, which may not provide a comprehensive representation of the entire tumour, leading to potential inaccuracies. Immuno-positron emission tomography (immuno-PET) represents an innovative imaging technique offering real-time, quantitative insights into PD-L1 expression levels. By employing radiolabelled molecules designed to target PD-L1, researchers can non-invasively monitor PD-L1 levels within tumours with improved precision.

Early experiments involving immuno-PET imaging in glioblastoma have yielded encouraging results. Radiolabelled agents designed to target PD-L1 exhibited rapid accumulation within tumours, facilitating clear imaging outcomes within a remarkably short time frame. While challenges persist, immuno-PET holds significant promise for advancing our understanding of how glioblastoma respond to immunotherapy and prioritise treatment for patients to improve outcome.

Immuno-PET Imaging of Tumour PD-L1 Expression in Glioblastoma - Cancers (Basel). 2023 Jun 9;15(12):3131.

Gitanjali Sharma, Marta C Braga, Chiara Da Pieve, Wojciech Szopa, Tatjana Starzetz, Karl H Plate, Wojciech Kaspera, Gabriela Kramer-Marek