Abstract 5466: Functional status of tumor-associated macrophages impacts clinical outcome of durvalumab in patients with advanced NSCLC as revealed by proteomics mass spectrometry
Authors: Hansen Anna Margaret , Wang Vivian Ying , Chambers Andrew , Chain David , Canales Jaime Rodriguez , Blando Jorge , Sweet Steve , Cooper Zachary A. , Gupta Ashok , Barrett Carl , Kim Yeoun Jin , Achour Ikbel 
Published: June 2023

Abstract
Introduction: Predictive biomarkers of anti‒PD-(L)1 therapies have largely focused on the tumor-T cell axis where tumor cell PD-L1 expression has demonstrated its clinical utility in predicting overall survival (OS) in patients with advanced NSCLC. In prior work using computational image analysis of multiplex immunofluorescence (mIF), we have shown the positive impact of CD68+ PD-L1+ macrophages in combination with CD8+ T cells in predicting long-term OS benefit in NSCLC patients treated with durvalumab (anti-PD-L1), highlighting the impact of the myeloid compartment on IO responses. In part, using proteomics mass spectrometry we sought to investigate further the functional impact of myeloid cells on the IO response and in particular, suppressive (M2) tumor associated macrophages (TAMs).
Methods: Pre-treatment tumor samples from 66 patients with advanced NSCLC patients enrolled in durvalumab nonrandomized phase 1/2 trial (10 mg/kg Q2W, CP1108/NCT01693562) were processed for global and targeted proteomics. A pathologist determined the tumor area and a single FFPE tumor tissue section was used for laser-capture macrodissection and protein extraction followed by mass spectrometry analysis using label-free, data-independent and parallel reaction monitoring.
Results: Among the immune associated proteins detected by proteomics mass spectrometry, we evaluated CD163 protein expression, a well-described marker of suppressive (M2) macrophages, and its impact on durvalumab clinical outcomes, alone and in relationship with PD-L1 and immune infiltration. While proteomics-based biomarker evaluable population (BEP) shows shorter median (m) OS compared to intended to treat population, we validated that high expression of PD-L1 as measured by IHC or proteomics associates with greater OS benefit as expected when treating with durvalumab. Building on this, the evaluation of protein associated with suppressive M2 macrophages, revealed that approximately 30% of NSCLC patients with high CD163 protein expression show poor OS benefit (5 months mOS) following durvalumab treatment. In contrast, patients with PD-L1 TC ≥50% and low CD163 expression derive greater OS benefit (13.4 months mOS) than those with high CD163 expression (5 months mOS) or with PD-L1 TC &lt;50% regardless of level of CD163 expression (4.1-7.4 months mOS). Moreover, patients with poorer outcome have significantly higher baseline CD163 protein expression as a proportion of total CD45 protein expression.
Conclusion: This analysis further confirms the importance of myeloid cell function within the tumor microenvironment (TME) in determining the outcome to T cell-directed IO therapy and highlights the utility of proteomics mass spectrometry in assessing more broadly and quantitatively the TME complementing findings based on RNAseq and IHC/mIF assays.
Citation Format: Anna Margaret Hansen, Vivian Ying Wang, Andrew Chambers, David Chain, Jaime Rodriguez Canales, Jorge Blando, Steve Sweet, Zachary A. Cooper, Ashok Gupta, Carl Barrett, Yeoun Jin Kim, Ikbel Achour. Functional status of tumor-associated macrophages impacts clinical outcome of durvalumab in patients with advanced NSCLC as revealed by proteomics mass spectrometry. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5466.