Abstract B020: NETosis-specific clipped histone H3 is a novel biomarker of response to neoadjuvant chemo-immunotherapy in resectable lung cancer

Abstract Introduction: Novel clinical cancer biomarkers are needed to better adjudicate the use of emerging therapies like immunotherapy in multimodal care. We evaluated plasma neutrophil extracellular traps (NETs) levels as one such biomarker due to the multifaceted and targetable roles of NETs in immune checkpoint inhibition resistance. Recently, histone H3 cleavage (H3Clip) was described as a sensitive and specific marker of NET release (NETosis) in humans. We therefore sought to develop H3Clip as a cancer biomarker for patients with resectable non-small cell lung cancer (NSCLC). Methods: We analyzed pre-treatment plasma samples from 47 patients with NSCLC who were assigned to up-front surgery, and 163 patients treated with neoadjuvant nivolumab monotherapy or nivolumab plus chemotherapy regimens as part of the phase II NADIM (NCT03081689), NADIM II (NCT03838159), and J1414 (NCT02259621) clinical trials. Circulating H3Clip levels were measured and correlated with the clinical outcomes of pathological complete response (pCR), major pathological response (MPR), recurrence free survival (RFS), progression-free survival (PFS) and overall survival (OS). Results: We found that baseline high H3Clip level was associated with significantly reduced OS and RFS in patients with NSCLC undergoing up-front surgery. Additionally, high H3Clip at baseline evaluation was associated with significantly shorter OS and PFS among patients receiving neoadjuvant chemo-immunotherapy. Among those who achieved a major pathological response to chemo-immunotherapy, high H3Clip was similarly associated with shorter OS and PFS. Among patients achieving a complete or partial clinical response to chemoimmunotherapy, high H3Clip was strongly associated with reduced OS and PFS. In this subgroup, the absolute difference in 30-month OS and PFS between the high and low H3Clip groups was 31% and 52%, respectively. High H3Clip patients were significantly less likely to achieve an MPR (p=0.0233; low vs high H3Clip: 76.92% vs. 52.50%) and pCR (p=0.0095; low vs. high H3Clip: 58.97% vs. 30.00%) to neoadjuvant chemo-immunotherapy. Finally, high H3Clip level was associated with shorter OS and PFS, and lower rates of pCR in the presence of high-risk clinical demographic features and low tumor PD-L1 expression. Conclusion: We demonstrate that H3Clip is a novel biomarker of prognosis and response to neoadjuvant chemo-immunotherapy in NSCLC through analysis of several phase II neoadjuvant chemo-immunotherapy trials. H3Clip is strongly associated with OS, PFS, RFS, MPR, and pCR and provides added clinical utility on top of routine demographic variables and biomarkers for risk stratification. NETs could thus represent both an important biomarker of response to chemo-immunotherapy and therapeutic target given their established effects on the tumor immune microenvironment. Citation Format: Muhammad H. Shahzad, Alberto Cruz-Bermudez, Roni F. Rayes, Ernest Nadal, Meghan L. De Meo, Mark Sorin, Simon Milette, Lyndon C. Walsh, Daniela F. Quail, Logan Walsh, Alex Martinez-Marti, Reyes Bernabe-Caro, Amelia Insa, Bartomeu Massuti, Belen Sierra-Rodero, Atocha Romero, Betty Giannias, Sara Najmeh, Pierre-Olivier Fiset, David S. Mulder, Lorenzo E. Ferri, Valsamo Anagnostou, Gavin Pereira, Kellie N. Smith, Drew Pardoll, Patrick Forde, Jonathan Cools, Mariano Provencio, Jonathan D. Spicer. NETosis-specific clipped histone H3 is a novel biomarker of response to neoadjuvant chemo-immunotherapy in resectable lung cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Mechanisms of Cancer Immunity and Cancer-related Autoimmunity; 2025 Sep 24-27; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(9 Suppl):Abstract nr B020.