PDCD1 and neoplasm: As tumor samples from HGSOC patients with mTLSs are associated with increased expression of co-inhibitory receptors (Fig. 2A–C), we quantified the levels of PDCD1, HAVCR2, and transcription factor 7 (TCF7; encoding a marker of progenitor T cells best known as TCF1) within the HGSOC microenvironment using spatial transcriptomics upon TLS localization on three H&E-stained consecutive FFPE sections from study cohort 1 (Fig. 3A).