GABA promotes resistance to immunotherapy of patients with TLS-positive tumours [RNA-seq]
Tertiary lymphoid structures (TLS) in the tumour microenvironment have been linked to positive clinical outcomes and responses to immune checkpoint inhibitors (ICI) in various cancers, including clear cell renal cell carcinoma (ccRCC) and soft tissue sarcoma (STS). However, a significant proportion of patients do not respond to ICI despite the presence of TLS. Our study unravels gamma-aminobutyric acid (GABA), a neurotransmission inhibitor, as a modulator of ICI resistance in TLS-positive tumours. By leveraging household and public multi-omic data, we demonstrated that GABA is upregulated in TLS-positive ccRCC and STS tumours from non-responders to ICI. In metastatic ccRCC, TLS from non-responders were distinguished from responders by a dysfunctional immune activation and a close proximity to GABA-producing proximal tubule-like tumour cells. The addition of a competitive inhibitor of GABA synthesis, 3-mercaptopropionic acid, significantly improved tumour control when compared to anti-PD1 alone when intra-tumourally injected in a mouse model of STS. Overall, our findings highlight GABA as a novel determinant of non-response to ICI in tumours harboring TLS, suggesting potential new approaches for patient stratification and personalized therapeutic strategies that could be applicable beyond metastatic ccRCC and STS. Overall design: Bulk RNA-seq (n=92, 82% TLS-positive) of ccRCC tumors from the BIONIKK cohort (NCT02960906)