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. 2023 Mar 13:13:1150349.
doi: 10.3389/fonc.2023.1150349. eCollection 2023.

Heterogeneity of tumour mutational burden in metastatic NSCLC demonstrated by endobronchial ultrasound sampling

Tracy L Leong  1   2   3   4 , Christian Aloe  5 , Savreet Aujla  5 , Hao Wang  5 , Velimir Gayevskiy  2   4 , Marie-Liesse Asselin-Labat  2   4 , Lesley-Ann Gray  6 , Daniel Steinfort  3   7 , Steven Bozinovski  5
Affiliations

Heterogeneity of tumour mutational burden in metastatic NSCLC demonstrated by endobronchial ultrasound sampling

Tracy L Leong et al. Front Oncol. .

Abstract

Introduction: Tumour mutational burden (TMB) is an important emerging biomarker for immune checkpoint inhibitors (ICI). The stability of TMB values across distinct EBUS tumour regions is not well defined in advanced lung cancer patients.

Methods: This study included a whole-genome sequencing cohort (n=11, LxG cohort) and a targeted Oncomine TML panel cohort (n=10, SxD cohort), where paired primary and metastatic samples were obtained by endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA).

Results: The LxG cohort displayed a strong correlation between the paired primary and metastatic sites, with a median TMB score of 7.70 ± 5.39 and 8.31 ± 5.88 respectively. Evaluation of the SxD cohort demonstrated greater inter-tumoural TMB heterogeneity, where Spearman correlation between the primary and metastatic sites fell short of significance. Whilst median TMB scores were not significantly different between the two sites, 3 out of 10 paired samples were discordant when using a TMB cut-off of 10 mutations per Mb. In addition, PD-L1 copy number and KRAS mutations were assessed, demonstrating the feasibility of performing multiple molecular tests relevant to ICI treatment using a single EBUS sample. We also observed good consistency in PD-L1 copy number and KRAS mutation, where cut-off estimates were consistent across the primary and metastatic sites.

Conclusions: Assessment of TMB acquired by EBUS from multiple sites is highly feasible and has the potential to improve accuracy of TMB panels as a companion diagnostic test. We demonstrate similar TMB values across primary and metastatic sites, however 3 out of 10 samples displayed inter-tumoural heterogeneity that would alter clinical management.

Keywords: biomarker; bronchoscopy; immunotherapy; lung cancer; tumour mutational burden.

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Conflict of interest statement

The author LG is employed by the company Australian Genome Research Facility Ltd., DS received honoraria from Astra Zeneca, Broncus Medical, Glaxo Smithkline, and research funding from Broncus Medical, Zidan Medical, and Morair MedTech. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Assessment of TMB heterogeneity using whole exome sequencing. (A) TMB scores derived from three databases including TCGA, canonical and CREV2 were used to determine the number of exonic mutations per Mb. (B) Spearman correlation analysis was performed to investigate the association between TMB values derived from (B) TCGA versus the canonical database and the (C) TCGA and CREV2 databases. (D) TMB scores at the primary (site 1) and metastatic site (site 2) were compared by Spearman analysis and (E) paired analysis was performed between site 1 and site 2. ns, not significant.
Figure 2
Figure 2
Assessment of TMB heterogeneity using the Oncomine panel. (A) TMB scores at the primary (site 1) and metastatic site (site 2) were compared by Spearman analysis and (B) paired analysis was performed between site 1 and site 2. (C) PD-L1 copy number at the primary (site 1) and metastatic site (site 2) were compared by Spearman analysis and (D) paired analysis was performed between site 1 and site 2. (E) KRAS G12/G13 mutations (G12A, G12C, G12D, G12R, G12S, G12V, G13D) were screened and a cut-off of 0.2% mutant allele frequency was used to determine presence of a KRAS mutation. KRAS mutation levels at the primary (site 1) and metastatic site (site 2) were compared by Spearman analysis and (F) paired analysis was performed between site 1 and site 2. ns, not significant.
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References

    1. Yarchoan M, Hopkins A, Jaffee EM. Tumor mutational burden and response rate to PD-1 inhibition. N Engl J Med (2017) 377:2500–1. doi: 10.1056/NEJMc1713444 - DOI - PMC - PubMed
    1. Schumacher TN, Schreiber RD. Neoantigens in cancer immunotherapy. Science (2015) 348:69–74. doi: 10.1126/science.aaa4971 - DOI - PubMed
    1. Yarchoan M, Burles JA, Lutz ER, Laheru DA, Jaffee EM. Targeting neoantigens to augment antitumour immunity. Nat Rev Cancer (2017) 17:569. doi: 10.1038/nrc.2017.74 - DOI - PubMed
    1. Hellmann MD, Ciuleanu TE, Pluzanski A, Lee JS, Otterson GA, Audigier-Valette C. Nivolumab plus ipilimumab in lung cancer with a high tumor mutational burden. N Engl J Med (2018) 378:2093–104. doi: 10.1056/NEJMoa1801946 - DOI - PMC - PubMed
    1. Vega DM, Yee LM, McShane LM, Williams PM, Chen L, Vilimas T. Aligning tumor mutational burden (TMB) quantification across diagnostic platforms: Phase II of the friends of cancer research TMB harmonization project. Ann Oncol (2021) 32:1626–36. doi: 10.1016/j.annonc.2021.09.016 - DOI - PubMed