3.1 Mutational landscape and characteristics of ERBB2 in non-small cell lung cancer
3.1.1 Basic mutational characteristics
55% (135/244) of ERBB2 mutations occurred in TKD, and 45% (109/244) occurred in non-TKD. In TKD, In_Frame_Insertion mutation (In_Frame_Ins) (45.08%, 110/135) was the most common type of mutation, followed by missense mutation (8.2%, 20/135). Among non-TKD, missense mutations (34.02%, 83/109) were the most common type (Table 1).
Table 1
Clinical characteristics of patients included in the study
Characteristics
|
TKD(N = 135)
|
non-TKD(N = 109)
|
Total(N = 244)
|
p-value
|
Cancer Type(%)
|
|
|
|
< 0.001
|
LUAD
|
129(52.87)
|
77(31.56)
|
206(84.43)
|
|
LUSC
|
0(0.0)
|
20(8.20)
|
20(8.20)
|
|
NSCLCa
|
6(2.46)
|
12(4.92)
|
18(7.38)
|
|
Annotation(%)
|
|
|
|
< 0.001
|
Oncogenic
|
130(53.28)
|
51(20.90)
|
181(74.18)
|
|
Benign
|
0(0.0)
|
33(13.52)
|
33(13.52)
|
|
Unknow
|
5(2.05)
|
25(10.25)
|
30(12.30)
|
|
Mutation Type(%)
|
|
|
|
< 0.001
|
In_Frame_Ins
|
110(45.08)
|
0(0.0)
|
110(45.08)
|
|
Missense_Mutation
|
20(8.20)
|
83(34.02)
|
103(42.21)
|
|
Otherb
|
5(2.05)
|
26(10.66)
|
31(12.70)
|
|
Smoker(%)
|
|
|
|
< 0.001
|
Yes
|
65(26.64)
|
61(25.00)
|
126(51.64)
|
|
No
|
61(25.00)
|
25(10.25)
|
86(35.25)
|
|
Unknow
|
9(3.69)
|
23(9.43)
|
32(13.11)
|
|
Person Cigarette Smoking
History Pack Year Value
|
|
|
|
|
Mean ± SD
|
11.36 ± 13.15
|
33.74 ± 28.79
|
22.38 ± 24.81
|
|
TMB
|
|
|
|
|
Mean ± SD
|
4.99 ± 5.99
|
15.27 ± 16.03
|
9.57 ± 12.65
|
|
PD-L1 score
|
|
|
|
|
Mean ± SD
|
42.92 ± 39.22
|
16.00 ± 35.78
|
35.00 ± 39.21
|
|
MSI Score
|
|
|
|
|
Mean ± SD
|
0.31 ± 1.75
|
1.36 ± 5.07
|
0.82 ± 3.75
|
|
Stage(%)
|
|
|
|
0.07
|
I
|
25(12.82)
|
35(17.95)
|
60(30.77)
|
|
II
|
6(3.08)
|
6(3.08)
|
12(6.15)
|
|
III
|
8(4.10)
|
9(4.62)
|
17(8.72)
|
|
IV
|
66(33.85)
|
40(20.51)
|
106(54.36)
|
|
T Stage(%)
|
|
|
|
0.23
|
T1
|
3(7.32)
|
12(29.27)
|
15(36.59)
|
|
T2
|
2(4.88)
|
14(34.15)
|
16(39.02)
|
|
T3
|
1(2.44)
|
2(4.88)
|
3(7.32)
|
|
T4
|
1(2.44)
|
1(2.44)
|
2(4.88)
|
|
TX
|
3(7.32)
|
2(4.88)
|
5(12.20)
|
|
N Stage(%)
|
|
|
|
0.74
|
N0
|
15(25.42)
|
30(50.85)
|
45(76.27)
|
|
N1
|
2(3.39)
|
3(5.08)
|
5(8.47)
|
|
N2
|
2(3.39)
|
3(5.08)
|
5(8.47)
|
|
N3
|
1(1.69)
|
0(0.0)
|
1(1.69)
|
|
NX
|
1(1.69)
|
2(3.39)
|
3(5.08)
|
|
Characteristics
|
TKD(N = 135)
|
non-TKD(N = 109)
|
Total(N = 244)
|
p-value
|
M Stage(%)
M0
|
7(17.50)
|
25(62.50)
|
32(80.00)
|
0.07
|
M1
|
3(7.50)
|
4(10.00)
|
7(17.50)
|
|
MX
|
0(0.0)
|
1(2.50)
|
1(2.50)
|
|
CT Size
|
|
|
|
|
Mean ± SD
|
2.40 ± 1.23
|
1.95 ± 1.13
|
2.23 ± 1.20
|
|
Sex(%)
|
|
|
|
0.12
|
Female
|
81(34.18)
|
51(21.52)
|
132(55.70)
|
|
Male
|
53(22.36)
|
52(21.94)
|
105(44.30)
|
|
Diagnosis Age
|
|
|
|
|
Mean ± SD
|
62.84 ± 10.68
|
64.26 ± 9.98
|
63.52 ± 10.35
|
|
Median[min-max]
|
64.00[37.00,86.00]
|
66.00[45.00,88.00]
|
65.00[37.00,88.00]
|
|
DFS
|
|
|
|
|
Mean ± SD
|
14.46 ± 15.87
|
28.66 ± 21.80
|
26.29 ± 21.23
|
|
a Specific pathological type was unknown. b Other mutations include Nonsense_Mutation, Frame_Shift_Del, Frame_Shift_Ins, Splice_Region, Splice_Site, and fusion. LAUD, lung adenocarcinoma; LUSC, lung squamous cell carcinoma; NSCLC, non-small cell lung cancer; TMB, Tumor Mutation Burden; DFS, Disease-Free Survival. |
3.1.2 Co-mutation in tumor genes and tumor suppressor genes
In patients with ERBB2 mutations, there were 14 cancer genes or tumor suppressor genes with at least 5% co-mutation rates, including TP53, EGFR, KRAS, PIK3CA, STK11, BRAF, and KEAP1. TP53 was the most common co-mutated gene in ERBB2 mutations (62.0%) and co-mutated with other genes more frequently in non-TKD patients than in TKD (Fig. 1).
3.2. Clinical characteristics of TKD and non-TKD in NSCLC
3.2.1 Basic clinical characteristics (Table 1)
3.2.1.1 Both TKD and non-TKD mutations mainly occur in lung adenocarcinoma. In lung squamous cell carcinoma, all mutations occur in the non-TKD mutant domain (p < 0.001). Six mutations were oncogenic in 20 patients with lung squamous cell carcinoma; eight had unknown mutation significance.
3.2.1.2 Most TKD mutations were oncogenic, while 39.2% were benign mutations in the non-TKD mutation (p < 0.001).
3.2.1.3 All In_Frame_Ins occurred in the TKD domain, while most of the Missense_Mutation occurred in the non-TKD domain (p < 0.001).
3.2.1.4 Non-TKD mutations occur more frequently in patients who smoke, and the smoking index (33.74 ± 28.79) is much higher than that in patients with TKD.
3.2.1.5 Patients with the non-TKD mutation had higher tumor mutation burden (TMB) and MSI score than those with TKD mutation (Fig. 2B-C).
3.2.1.6 TKD mutation had a higher PD-L1 score than those with the non-TKD mutation.
In addition, there were no significant differences in tumor stage, size, gender, and age between non-TKD and TKD patients. The mean age at diagnosis of TKD was 62.84 ± 10.68; 60% were female, and 48% were smokers. Among all TKD mutations, Y772_A775dupYVMA was the most dominant mutation (51.1%, 69/135), followed by G778_P780dupGSP (8.1%, 11/135) and G776delinsVC (10.4%, 14/135). Among all non-TKD mutations, S310F was the most dominant mutation (11% 12/109), followed by R103Q (6.4% 7/109). The most common mutations above were oncogenic mutations.
3.2.2 Survival prognosis
In the database of cbioportal, the PFS of non-TKD is longer than TKD and has statistical difference(p < 0.001) (Fig. 2A).
3.3 The identification of differentially expressed genes and Enrichment Analysis.
3.3.1 Differential genes: 788 DEGs were screened, and p < 0.01 was the threshold after adjustment. Compared with non-TKD samples, 638 up-regulated and 149 down-regulated DEGs were identified in TKD samples.
3.3.2 Enrichment Analysis of functional pathway
The function and pathway enrichment of 638 up-regulated DEG genes were analyzed. CC-related DEGs were significantly enriched in the collagen-containing extracellular matrix, endolysosomes, and granular secretory membrane (Fig. 3A). BP-related DEGs were significantly enriched in leukocyte activation, migration, and activation involved in the immune response (Fig. 3B). DEGs linked to MF are significantly enriched in immune receptor activity, cytokine receptor activity, sialic acid binding, and phosphoric diester hydrolase activity (Fig. 3C).
3.4 Construction of the PPI Network and Identification of Hub Genes
LYN, BTK, PIK3CA, STAT3, KITLG, STAT5A, EPOR, INPP5D, LCP2, and MS4A2, the top ten genes obtained through PPI and Cytoscape analysis, were considered as hub genes. LYN, BTK, and PIK3CA genes were in the most critical position and became the focus of subsequent research (Fig. 3D-F).
3.5 LYN, BTK, and PIK3CA mutation and prognosis.
The above study identified LYN, BTK, and PIK3CA genes as hub genes. In the cbioportal database, the predictive effect of the above hub gene mutation on the prognosis of patients with NSCLC-ERBB2 mutation was further investigated. Due to the small number of commutant BTK or LYN in ERBB2, the prognostic effect cannot be further predicted. The overall survival of PIK3CA mutation was compared in patients with TKD and non-TKD mutations, and there was no significant difference between the two groups. (Fig S1) The LYN, BTK, and PIK3CA mutations were compared in all NSCLC patients. Compared with wild-type patients, patients with LYN or BTK mutations had no significant difference in PFS(Fig. 4A-B). However, patients with PIK3CA mutations had longer PFS than wild-type patients. The combination of BTK, PIK3CA, and LYN mutation was superior to single prediction (p 5.95e-10) (Fig. 4D-G), indicating that viewing BTK, LYN, and PIK3CA mutation as a whole could better predict the prognosis of NSCLC patients.
3.6 Selecting sensitive drugs for patients with TKD and non-TKD mutations by oncoPredict
To find drugs suitable for patients with TKD and non-TKD mutations, we used the oncoPredict algorithm to convert the gene expression of TKD and non-TKD mutant samples into a drug susceptibility matrix (Table S1). Compared with the TKD group, the non-TKD group had a better response to Gefitinib_1010 (targeted drug, EGFR inhibitor), Rapamycin_1084 (targeted drug, PI3K/ mTOR inhibitor), Sorafenib_1085 (targeted drug, Receptor tyrosine kinase inhibitor), Linsitinib_1510 (targeted drug, IGF1R inhibitor), Uprosertib_1553 (targeted drug, AKT inhibitor), OSI-027_1594 (targeted drug, IGF1R inhibitor) mTOR inhibitor), VE-822_1613 (targeted drug, ATM inhibitor), WnT-C59_1622 (targeted drug, Wnt inhibitor), I-BET-762_1624 (targeted drug, BET inhibitor), OTX015_1626 (targeted drug, ATM inhibitor) BRD2/3/4 inhibitors), AZD5153_1706 (targeted drugs, BRD4 inhibitors), Ibrutinib_1799 (targeted drugs, BTK inhibitors), Oxaliplatin_1806 (chemotherapy drugs), Carmustine_1807 (Chemotherapy drug), Dihydrorotenone_1827 (mitochondrial inhibitor), OF-1_1853 (chemotherapy drug), AZD3759_1915 (targeted drug, EGFR inhibitor), GDC0810_1925 (Estrogen receptor depressant), GSK2578215A_1927 (targeted drug, LRRK2 inhibitor), I-BRD9_1928(targeted drug, BRD9 inhibitor), NVP-ADW742_193 (Targeted drug, IGF-1R inhibitor), Savolitinib_1936 (targeted drug, MET inhibitor), BIBR-1532_2043 (apoptosis inducer), MK-8776_2046 (targeted drug, Chk1 inhibitor), Ulixertinib_2047 (targeted drug, ERK1/2 kinase inhibitor), VX-11e_2096 (targeted drug, ERK inhibitor), Uprosertib_2106 (targeted drug, Akt inhibitor), LJI308_2107 (targeted drug, RSK inhibitor). AZD6482_2169(targeted drug, PI3K inhibitor), Doramapimod_1042(targeted drug, MAPK inhibitor), SB505124_1194(targeted drug, TGFβR inhibitor), Daporinad_1248(target drug, TGFβr inhibitor), Daporinad_1248(Targeted drugs, NAMPT inhibitors), Lapatinib_1558(targeted drugs, EGFR inhibitors) are more sensitive in TKD. Based on the boxplot results, the significantly differentially sensitive drugs in the two groups were visualized (Fig. 5).
3.7 Therapeutic response in patients with TKD and non-TKD mutation
Two patients with TKD mutation and two with non-TKD mutation were collected on the clinical characteristic and the outcome of antitumor therapy. One patient with TKD mutation and one with non-TKD were treated with pyrotinib. PFS of the TKD mutation patient was as prolonged as 5.8 months, but no therapeutic effect was observed in the non-TKD one due to loss of follow-up. One TKD mutation and one non-TKD mutation were treated with disitamab vedotin, with PFS of 1.2 months and 1.5 months, respectively. One patient with common TKD mutation was treated with DS-8201 and had PFS for 6.5 months (Fig. 6). During the treatment of DS-8201, tumor markers decreased significantly. CEA decreased from 515ug/L to 112ug/ L; CA125 decreased from 1003KU/L to 110KU/L; NSE decreased from 38.1ug/L to 15.8ug/L. When drug resistance occurred, CEA, CA125, and NSE increased to 407ug/L, 1995KU/L, and 34.1ug/L, respectively (Fig. 7A). The other non-TKD mutation patient was treated with DS-8201, with PFS of 3.7 months. During therapy, CEA decreased from 11522ug/L to 7187ug/ L; CA125 decreased from 452KU/L to 318KU/L; NSE decreased from 112ug/L to 35.2ug/L. When drug resistance occurred, CEA, CA125, and NSE increased to 8619ug/L, 418KU/L, and 30.8ug/L, respectively (Fig. 7B).