Expression differences of programmed death ligand 1 in de-novo and recurrent glioblastoma multiforme
Heynckes S, Gaebelein A, Haaker G, Grauvogel J, Franco P, Mader I, Carro MS, Prinz M, Delev D, Schnell O, Heiland DH.
The biology of recurrent glioblastoma multiforme (GBM) is a dynamic process influenced by selection pressure induced by different antitumoural therapies. The poor clinical outcome of tumours in the recurrent stage necessitates the development of effective therapeutic strategies. Checkpoint-inhibition (PD1/PD-L1 Inhibition) is a hallmark of immunotherapy being investigated in ongoing clinical trials. We show that PD-L1 expression was reduced in recurrent GBM in comparison to de-novo GBM. Additionally, patients who received an extended dose of temozolomide (TMZ) chemotherapy showed a significantly reduced level of PD-L1 expression in the recurrence stage compared to the corresponding de-novo tumour. Our findings may provide an explanation for potentially lower response to immunotherapy in the recurrent stage due to the reduced expression of the therapeutic target PD-L1.
