82P - Longitudinal proteomics and single-cell transcriptomics reveal HDAC3 as an immunotherapy biomarker in advanced non-small cell lung cancer

Background

Autoantibodies (AAbs) hold promise for monitoring treatment responses in cancer immunotherapy. We propose a comprehensive longitudinal analysis of an AAb panel to predict treatment responses in advanced NSCLC during immunotherapy. Furthermore, it explores the functional implications of HDAC3 on the immune microenvironment at the single-cell transcriptomics and protein level.

Methods

A total of 131 plasma samples were collected from 55 advanced NSCLC patients undergoing anti-PD1 monotherapy from 2016 to 2022. Utilizing the high-density HuProt^TM antigen microarray (21,000 proteins), predictive AAbs were identified by comparing responders and non-responders(n=22 with 53 plasma samples). Subsequently, an independent cohort (n=33 with 78 plasma samples) underwent validation for candidate AAbs. The prognostic value of HDAC3 was confirmed through immunohistochemistry (IHC). Employing single-cell transcriptomics and multiple immunohistochemistry (mIHC), analyses were conducted on cell communication between HDAC3+ and HDAC3- malignant lung cells.

Results

Five predictive AAbs (HDAC3, METTL21C, HSPB3, SPACA7, and SPPL2B) were selected and validated. The baseline AAbs predictive efficacy achieved an area under the curve (AUC) of 0.76, 0.76, 0.74, 0.77 and 0.75. After treatment, the AUC were 0.84, 0.78, 0.72, 0.76, and 0.76. HDAC3 AAb demonstrates the most robust prognostic capability. Employing the five AAbs as a risk score classifier, PFS could be accurately distinguished (P = 0.014 and P = 0.023). Compared with HDAC3- malignant lung cells, HDAC3+ malignant lung cells exhibited higher chromosome copy number variation, senescence and EMT scores (P < 0.0001) and were enriched in PI3K−AKT−MTOR, and P53 signaling (P < 0.05). Single-cell transcriptomics, IHC and mIHC confirmed that increased infiltration of HDAC3+ malignant lung cells correlated with decreased CD4⁺T and CD8⁺T cells and an increase in TGFβ signaling.

Conclusions

This study highlights AAb signatures as potential biomarkers for monitoring aNSCLC undergoing immunotherapy. HDAC3 emerges as a potent prognostic indicator and HDAC3+ lung malignant cells exhibited enhanced malignancy with immunosuppressive microenvironment.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.