Single-cell multiplexed proteomics to identify novel polyfunctional CD8+ T cell signatures induced by nivolumab in head and neck cancer patients after salvage surgery.

Abstract

6576 Background: Immune checkpoint inhibitors (ICIs) are FDA approved for use in head and neck squamous cell cancer (HNSCC), however, only ~20% patients achieve a response. Identification of biomarkers of response or toxicity remains a challenge. Polyfunctional T-cells, or T-cells producing multiple cytokines, have been recognized as contributors to durable immunity against various cancers. However, their role has not been studied prospectively in HNSCC patients receiving ICIs. To look for an early predictor of response, we used single-cell functional proteomic profiling (IsoPlexis) on blood samples pre- and post- first dose of nivolumab (nivo) in patients on our phase-II study of locally recurrent HNSCC (NCT03355560). Methods: HNSCC patients who failed definitive radiation +/-chemotherapy and were subsequently treated with curative intent salvage resection were enrolled to receive 6 months of nivo beginning 4 to 11 weeks after surgery. Blood samples were collected before and after the first dose of nivo. Peripheral blood mononuclear cells were isolated, enriched for CD8+ T cells and using the 32-plex IsoCode technology, single-cell cytokine signals were captured and polyfunctional strength of CD8+ T cells was evaluated across four groups (effector, stimulatory, regulatory, inflammatory). A comparison analysis was performed between pre- and post- nivo treatment and between patients who relapsed (non-responders) vs those who did not (responders). Results: Thirty-three of 39 planned patients have been enrolled, of which 28 are evaluable and 5/28 (18%) developed recurrence. Median age is 68 years (range 51-85), 9/28 (32%) patients are female, 26/28 (93%) are white, disease sites include oropharyngeal 6/28 (21%), oral cavity 11/28 (39%) and larynx 11/28 (39%). Samples were evaluated at a median follow up of 5.9 months from enrollment. Single-cell analysis demonstrated a strong upregulation of polyfunctional human CD8+ T cell subsets in responders. Polyfunctional Strength Index (PSI) was enhanced in CD8+ T cells across the responders’ samples, composed largely of effector cytokines (granzyme-β, IFN-γ, MIP-1α, perforin, TNF-α). Conclusions: Single-cell functional proteomic analysis revealed significantly upregulated polyfunctional profiles and an increase in effector cytokines in patients who responded to nivo. This data provides important insights into PD-1 inhibitor triggered T-cell activity and may be used to predict response to ICIs in HNSCC patients using a blood test. Clinical trial information: NCT03355560 .