Abstract 4526: Molecular landscape of clonal hematopoiesis in patients with lung cancer: First results of the CHIC study
Authors: Tagliamento Marco , Marzac Christophe , Aldea Mihaela , Vasseur Damien , Bayle Arnaud , Gazzah Anas , Ngocamus Maud , Nicotra Claudio , Rodriguez Julieta , Levy Antonin , Baldini Capucine , Ponce Santiago , Blanc-Durand Felix , Rouleau Etienne , Italiano Antoine , Lacroix Ludovic , Friboulet Luc , Planchard David , Barlesi Fabrice , Loriot Yohann , Micol Jean-Baptiste , Besse Benjamin 
Published: April 2023

Abstract
Introduction: CHIC (Clonal Hematopoiesis In Lung Cancer) is a retro-prospective study that aims to describe the characteristics of clonal hematopoiesis (CH) in patients with non-small cell lung cancer (NSCLC). We present preliminary results from the retrospective cohort.
Experimental procedures: A retrospective analysis conducted in patients with metastatic or recurrent NSCLC included in the MATCH-R study (NCT02517892) at Gustave Roussy (Villejuif, France). CH was evaluated by a 74-gene targeted NGS panel (HaloPlex - Agilent) performed on DNA extracted by isolated-by-blood leukocytes. The variant allele frequency (VAF) threshold of detection was set at 1%.
Results: 108 consecutive patients with advanced NSCLC included from October 2015 to July 2019 were evaluated, irrespective of the tumor molecular profile. 46% of the patients were female, 67% were former or current smokers. 82% of the patients had adenocarcinoma and 44%, 23%, 33% had bone, liver and/or brain metastases, respectively. Patients had received a median of 2 lines of systemic therapy and 81% were on active anticancer treatment at the time of CH assessment. At least one CH mutation was found in 38 out of 108 patients (35% prevalence), with an increasing with age trend. Patients carrying CH were older as compared to those without CH and had in 29% vs. 11% of cases tumor histology other than adenocarcinoma (p=0.009). No difference in overall survival was observed according to CH detection (log rank p=0.318). We found 64 mutations in 19 different genes: 63% of the patients carried a single mutation, while co-occurrence of two, three, four or five mutations, within the same gene or in more than one, was found in seven (18%), four (11%), one (3%) and two patients (5%), respectively. Epigenetic modifiers (DNMT3A, TET2, ASXL1) were the most frequently mutated genes: 38 mutations with a median VAF of 6.5% detected in 32 patients. DNA repair genes (PPM1D, TP53, CHEK2, ATM) were the second most frequently mutated: 11 mutations at a median VAF of 4% were detected in 9 patients. 7 mutations in genes encoding for the cohesin complex (SMC3, SMC1A, RAD21, STAG2) were found in 6 patients, with a median VAF of 5%. A non-simultaneous cfDNA sequencing by FoundationOne Liquid CDx assay (324-gene panel) was performed in 9 patients for tumor profiling. In 2 out of 3 tested cases the presence of CH was confirmed in plasma liquid biopsy. 4 patients with no detectable CH by the targeted blood sequencing subsequently were found having CH mutations in plasma NGS, on average 45 months apart. To note, as many as 5 out of the 19 detected mutated genes (PPM1D, SMC3, SMC1A, PRPF8, ZRSR2) are not part of the FDA-approved NGS panel used for cfDNA profiling in solid tumors.
Conclusion: We found a consistent prevalence of CH in patients with NSCLC by using a sequencing approach targeted for hematologic disorders. Prognostic implications of CH are under investigation and will be evaluated in the full cohort.
Citation Format: Marco Tagliamento, Christophe Marzac, Mihaela Aldea, Damien Vasseur, Arnaud Bayle, Anas Gazzah, Maud Ngocamus, Claudio Nicotra, Julieta Rodriguez, Antonin Levy, Capucine Baldini, Santiago Ponce, Felix Blanc-Durand, Etienne Rouleau, Antoine Italiano, Ludovic Lacroix, Luc Friboulet, David Planchard, Fabrice Barlesi, Yohann Loriot, Jean-Baptiste Micol, Benjamin Besse. Molecular landscape of clonal hematopoiesis in patients with lung cancer: First results of the CHIC study. [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 4526.