Paper - Review

DOI: 10.1038/s41467-020-19855-x

Abstract

Evolutionary trajectories
← of early LUAD (Lung Adenocarinoma)
→ have NOT ❌ been → fully elucidated

Genomic analysis
← between 1⃣ pre-invasive 2⃣ invasive components
→ will facilitate → the description of LUAD evolutionary patterns

MPNs
← micro-dissect malignant pulmonary nodules
→ into paired 1⃣ pre-invasive 2⃣ invasive components
→ for 1⃣ panel-genomic sequencing 2⃣ recognize → 3 evolutionary trajectories

EM1
← evolutionary mode 1
→ demonstrates → none ❌ of the common driver events
← between paired components

EM2A & EM2B
→ exhibit → critical private alternations
← which restricted to 1⃣ pre-invasive 2⃣ invasive components

Truncal mutation abundance
→ decrease ↓ → after the acquisition of invasiveness
← which may be associated with ← the intra-tumoral accumulation of infiltrated B cells

Introduction

LUAD
← lung adenocarcinoma
→ is the most commonly diagnosed ← sub-type of lung cancer
→ is the leading cause of cancer deaths

CT screening
→ has resulted in a drastic increase ↑
← in MPNs ← Malignant Pulmonary nodules

LUAD
→ is still considered → a hetero-geneous prognosis disease

Tumor invasive status
→ has a notable impact ← on prognosis of LUAD

∴ Early invasive LUAD
→ had a worse prognosis ← with a certain recurrence rate

The invasive components in MPNs
→ e.g. 1⃣ MIA ← minimally invasive adenocarcinoma 2⃣ IAC ← invasive adenocarcinoma
→ are 1⃣ important precise prognostic discriminator 2⃣ better than the T descriptor of the TNM staging system

Genome-wide somatic mutation analysis
→ has advanced our understanding ← of critical molecular events
← in 1⃣ cancer progression 2⃣ cancer evolution

Significant genetic differences
← among 1⃣ AAH 2⃣ AIS 3⃣ MIA

Pre-invasive & invasive LUAD
→ have never ❌ been investigated ←within a single MPN

EGFR & KRAS
→ are frequently mutated driver genes ← of LUAD

Early-stage EGFR-mutated NSCLC
← Non-small-cell lung cancer
→ usually have a better 👍 prognosis ← then 1⃣ wild-type 2⃣ KRAS-mutated cases

EGFR mutation
→ is considered → a positive prognostic marker
← of both 1⃣ DFS ← disease-free survival 2⃣ OS ← overall survival

❓: How these dominant driver genes → affect early progression
→ from pre-invasive toe invasive LUAD

Included ← 53 T1 stage LUAD cases
← with 1⃣ micro-dissection 2⃣ panel-genomic-sequencing methods
→ to delineate 1⃣ the driver molecular events 2⃣ early invasive progression ← in MPNs

Results

Study workflow and genetic landscape

A total of 53 cases
→ were included
→ for 1⃣ the genomic sequencing 2⃣ data analysis

All 53 LUAD patients → were diagnosed
→ with 1⃣ MPN < 3 cm 2⃣ pathologically confirmed adenocarcinoma 3⃣ lymph node metastasis

61 of 69 MPNs
→ were conducted with micro-dissection
→ to separate 1⃣ pre-invasive 2⃣ adjacent invasive components

1-34 somatic mutations
→ were identified ← in each MPN component ← of the phase 1 study

1-15 somatic mutations
→ were observed ← in the subsequent phase 2 study

NO ❌ significant differences
← in these driver genes
→ were observed between 1⃣ pre-invasive 2⃣ invasive MPN components

Phylogenetic analyses within MPNs revealed three evolutionary trajectories

Analyzed on 52 paired 1⃣ pre-invasive 2⃣ adjacent invasive MPN components
→ to investigate → the evolutionary relationship between 1⃣ early pre-invasive 2⃣ invasive LUAD ← within the MPNs

5 MPNs ← from 3 cases revealed
→ NO ❌ truncal driver mutations
← between 1⃣ pre-invasive 2⃣ adjacent invasive components
← which indicated → pre-invasive and invasive LUAD → were driven ← by different driver events in this situation

A total (← of 45 MPNs harbored truncal critical alterations)
← between 1⃣ pre-invasive 2⃣ adjacent invasive components

Detected → key mutations
← which restricted ← to pre-invasive branches
← which were classified ← as EM2A

Revealed → a potential linear progression
→ for 1⃣ pre-invasive 2⃣ adjacent invasive LUAD

NO ❌ private mutations → were discovered
← in the remaining 2 MPNs

Quantified → ITH (← Intra-tumor hetero-geneity) ← of paired components
← within each evolution mode

∴ 1⃣ EM1 → got the highest ITH level 2⃣ EM2B → had the lowest ITH level

ITH level (← of invasive components)
→ was significant higher
← than the adjacent pre-invasive components

Dominant driver genes in truncal mutations

1⃣ EGFR 2⃣ TP53 3⃣ KRAS 4⃣ STK11
→ were recurrently mutated (driver genes)
Almost all truncal mutation genes
→ were (known drivers)

1⃣ EGFR 2⃣ CDK4 3⃣ TP53
→ were the top frequently altered driver genes
← of the invasive branching mutations

TP53
→ carried the highest number of alterations
← in the pre-invasive branch mutation profile

RTK-RAS pathway-related genes
← e.g. 1⃣ EGFR 2⃣ KRAS 3⃣ ERBB2
→ contributed mostly → to truncal mutations
← both in two-phase studies

Potential functions of TSGs
← Tumor suppressor genes
← in effecting tumor evolution
→ critical double-hit events of TSGs
← including 1⃣ gene loss 2⃣ homo-zygotic mutations 3⃣ loss of hetero-zygosity

1⃣ EGFR 2⃣ KRAS 3⃣ STK11
→ dominant truncal driver genes

Truncal EGFR mutation is associated with strong selective pressure and B cell infiltration

Abundance (← of identified truncal EGFR mutations)
← between 1⃣ pre-invasive 2⃣ adjacent invasive component

Abundance of EGFR mutation
← in the invasive component
→ was significantly lower ← than that in the adjacent pre-invasive component

Abundance change (← of truncal mutation)
← between 1⃣ MPNs harboring 2⃣ not harboring EGFR mutations

∴ truncal mutation abundance ← in EGFR-mutated MPNs
→ was significantly reduced

Strong selective pressure ← on EGFR-mutated tumor cells
← during the acquisition of invasiveness

Association ← between 1⃣ mutation 2⃣ inflammatory infiltration
← in NSCLC patients

∴ Selective pressure ← from inflammatory infiltration
→ contributed to the differential prognosis
← in T1 stage LUAD patients

Performed → immuno-histochemistry (IHC) assays
→ to evaluate 1⃣ the micro-enviromental B 2⃣ T cell infiltration of EGFR-mutated cases
∴ B cell were present at higher ↑ level
← in the invasive components ← than the adjacent pre-invasive component

Discussion

The histological continuum
→ preceding early invasive progression
← in LUAD

Evaluating → the evolutionary trajectory of (early invasive LUAD)
→ is critical ❗
→ 1⃣ to elucidate → the mechanism of early invasive progression 2⃣ to classify → molecular genotypes 3⃣ to provide → potential strategies → for early intervention

Previous study
→ found that 1⃣ KRAS 2⃣ TP53 3⃣ EGFR mutations were indicators
← of malignant transition ← from AAH to AIS/MIA

1⃣ BRAF 2⃣ KRAS
→ were initiated as driver events ← in AAH
1⃣ EGRF 2⃣ TP53
→ were secondary driver events ← in LUAD

1⃣ EGFR 2⃣ ERBB2 3⃣ NRAS 4⃣ BRAF
→ were early clonal genomic events ← in AIS
TP53
→ was only found in 1⃣ MIA 2⃣ IAC

Evolution is always branched
→ the result demonstrated
→ 1⃣ pre-invasive 2⃣ adjacent invasive LUAD
← arose from branching evolution in 62% of MPN samples

Invasive progression (← in a single lesion)
→ was never ❌ investigated
→ to the best of knowledge

Genomic relationships
← between 1⃣ pre-invasive 2⃣ invasive components

∴ 1⃣ Pre-invasive 2⃣ invasive components
→ were mostly evolutionary results of branched evolution

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