Immune-featured stromal niches associate with response to neoadjuvant immunotherapy in oral squamous cell carcinoma.

Tumor stromal cells (TSCs) play a crucial yet underexplored role in the tumor microenvironment (TME). This study uses single-cell sequencing and spatial transcriptomics on paired tumor specimens from 22 patients with oral squamous cell carcinoma (OSCC) enrolled in a randomized two-arm phase 2 trial, receiving neoadjuvant anti-PD-1 mono-immunotherapy or anti-PD-1 plus docetaxel-cisplatin-5-fluorouracil (TPF) immunochemotherapy. Single-cell analysis reveals increased TSCs within the TME of responders in immunochemotherapy. Notably, significant post-treatment upregulation of SELP(+) high endothelial venules (HEVs) and APOD(+) myofibroblastic cancer-associated fibroblasts (myCAFs), alongside a decline in STMN1(+) capillary endothelial cells (cECs), is specific to the immunochemotherapy cohort. In contrast, MYF5(+) muscle satellite cells (MSCs) are upregulated in non-responders to mono-immunotherapy. SELP(+) HEVs and APOD(+) myCAFs foster favorable immunomodulatory stromal niches for improved outcomes, while STMN1(+) cECs and MYF5(+) MSCs form immunosuppressive niches in tumor invasion regions, highlighting therapeutic targets. The trial was registered at ClinicalTrials.gov, and the registration number is NCT04649476.