Clinical - CAR-T therapy immune response

Diffuse midline glioma (DMG) is a rare, aggressive type of brain tumour that mainly affects children but can also occur in adults. Surgical removal is extremely difficult or impossible without damaging critical functions - it is incurable and uniformly fatal.

Dr. Tessa Gargett and her colleagues at the Centre for Cancer Biology (an alliance between SA Pathology and UniSA) are focusing on treating DMGs using a type of immunotherapy called ‘CAR-T’ (Chimeric Antigen Receptor T-Cell). CAR T-cell therapy for diffuse midline glioma (DMG) is one of the most active areas of research right now, because conventional treatments haven’t changed survival outcomes much in decades.

CAR-T therapy is a personalised cell therapy that involves genetically modifying T-cells collected from a patient’s blood to express antigen receptors that can specifically recognise tumour cells. Selecting targets is very challenging as they need to be highly expressed on tumour cells, minimally present on healthy cells and accessible in the CNS.

There is tremendous excitement about the potential for CAR-T in DMG as it has been the first treatment to show any meaningful tumour control for these children. There are many challenges to overcome, including safety concerns (due to cytokine release syndrome and neurotoxicity), delivery challenges (BBB permeabilisation and intraventricular delivery), and the many inherent challenges with manufacturing for CAR-T therapies.

Tessa and her colleagues are participating in a phase 1 trial of this therapy that is the first of its kind in Australia, or indeed anywhere in the world outside the US. The role of their lab is CAR-T preparation and biomarker analysis. They bank PBMCs (peripheral blood mononuclear cells) covering the time course in patients receiving CAR-T therapy. By performing single cell RNA sequencing on these samples, the aim is to track changes in CAR-T cells after infusion as they expand in the blood, and also detect any changes in potentially detrimental immune-suppressive cell populations.

Dr. Tessa Gargett was the successful recipient of the Parse CSP Grant Award, which entitled her lab to a Whole Transcriptome Evercode™ kit for 100,000 cells. Single cell sequencing was provided free of charge by the SAGC on the DNBSEQ-T7.

The Parse technology was an excellent fit for this application as it allowed these precious samples to all be fixed as they became available at different time points and run together in a single library preparation round helping to minimise batch effects. Parse workflow does not require a specialised instrument therefore provides more flexibility to be completed in any molecular lab with standard multichannel pipettes and centrifuge machine