AimThis study was designed to determine the risk factors of lymph node metastasis in non‐small cell lung cancer (NSCLC) patients with tumors ≤ 2 cm, using the Shanghai Chest Hospital Lung Cancer Database.MethodsFive hundred and eighteen patients with NSCLC ≤ 2 cm were included in this study, and were classified into lymph node‐positive and lymph node‐negative groups. Univariate and multivariate logistic regression analyses were performed to select the independent risk factors for lymph node metastasis in NSCLC patients.ResultsNo evidence of metastasis was found in tumors ≤ 1 cm, all positive results were in tumors sized 1–2 cm. Imaging characteristics, including solid and part‐solid nodules, were strongly associated with lymph node metastasis (odds ratio [OR] 24.959, 95% confidence interval [CI] 5.999–103.835, P < 0.001; OR 12.559, 95% CI 3.564–44.259, P < 0.001) and subgroup logistic analysis (OR 21.384, 95% CI 5.058–90.407, P < 0.001; OR 11.632, 95% CI 3.290–41.126, P < 0.001). Greater lymph node metastasis was observed in non‐adeno non‐squamous carcinoma. The presence of pleural invasion and carcinoembryonic antigen levels indicated lymph node dissection. Similar results were revealed in subgroup analysis in tumors ≤ 2 to > 1 cm.ConclusionSize had a great impact on lymph node metastasis, especially tumors of 1–2 cm. Preoperative imaging, non‐adeno non‐squamous carcinoma, pleural invasion, and carcinoembryonic antigen all indicated lymph node dissection. There was no discrepancy between N1 and N2 positive lymph nodes.

The epidermal growth factor receptor 2 (HER2) has been established as an important target of HER2-positive lung cancer, but somatic mutations in HER2 kinase domain are frequently observed that may cause drug resistance and sensitivity for tyrosine kinase inhibitors (TKIs). In this study, the response profile of 14 small-molecule TKIs upon 11 clinical HER2 mutations was investigated systematically using a synthetic strategy that integrated in silico analysis and in vitro assay to explore the structural basis, energetic property and biological implication underlying the intermolecular interactions of TKIs with wild-type and variant HER2. It is found that most clinical mutations are far away from HER2 active site and thus can only address modest or moderate effect on inhibitor binding. However, few single-point substations such as D769H and D769Y as well as the gatekeeper mutation T798 M were predicted to cause strong resistance for an array of TKIs by reshaping the geometric feature and physiochemical property of the active site. Furthermore, inhibitor response to the most common insertion mutation in HER2 exion 20 (HER2(YVMA) ) was examined in detail; the response can be grouped into three classes: sensitization, resistance and insusceptibility. The Bcr-Abl inhibitor bosutinib and EGFR inhibitor gefitinib were selected as the representatives of, respectively, sensitization and insusceptibility to perform kinase assay against the GST-tagged, recombinant kinase domains of wild-type HER2(WT) and HER2(YVMA) variant. As expected, the biological activity of bosutinib was improved by ∼160-fold due to the insertion, while gefitinib exhibited low inhibitory potency on both HER2(WT) and HER2(YVMA) (IC50>100 μM). Structural analysis revealed an intensive network of hydrogen bonds and hydrophobic interactions in HER2(YVMA) bosutinib complex, whereas only few nonspecific van der Waals contacts were observed at the complex interface of HER2(YVMA) with gefitinib.

The oncogenic protein MDM2 is an important negative regulator of p53 tumour suppressor. Overexpression of this protein is closely related to the pathological progression and metastasis of lung cancer and other tumours. Previously, a 12-mer peptide segment 17ETFSDLWKLLPE28 (p5317–28) corresponding to residues 17–28 of the human p53 transactivation domain was identified to interact moderately with MDM2. Here, we successfully created an orthogonal molecular interaction system between a native hydrogen bond (H-bond) and a designed halogen bond (X-bond) across the protein–peptide complex interface, where the X-bond was introduced by substituting the 3-hydrogen atom of the benzene ring of the p5317–28 Phe19 residue with a halogen atom X, resulting in a series of 3X-peptides (X = F, Cl, Br or I). Theoretical analysis found that chlorine is a good compromise between X-bonding strength and steric hindrance due to introducing a bulkier halogen atom to the tightly packed complex interface. Consequently, the 3Cl-peptide (Kd = 105 nM) was determined to exhibit ~5-fold affinity improvement relative to p5317–28 (Kd = 570 nM). In contrast, the binding affinity of the 2Cl-peptide (Kd = 492 nM), a negative control that cannot form the X-bond according to computational analysis, did not change considerably on the halogenation.