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Background: Src homology region 2 domain‐containing phosphatase 2 (SHP2) is a novel target for Kirsten rat sarcoma oncogene (KRAS) mutant cancer. We retrospectively studied the significance of SHP2 in KRAS mutant non‐small cell lung cancer (NSCLC) treated with immunotherapy and its relationship with tumor microenvironment (TME). Methods: Sixty‐one advanced KRAS mutant NSCLC patients who underwent immunotherapy were enrolled. Next‐generation sequencing (NGS) was used to profile mutation status. The expression of SHP2, phospho‐SHP2 (pSHP2), and programmed death ligand 1 (PD‐L1) were analyzed by immunohistochemistry (IHC). Quantitative multiplexed immunofluorescence cytochemistry (mIFC) analysis was conducted to describe the TME. Results: SHP2 was heterogeneously expressed in 32 samples in both tumor cells and immune cells and highly expressed (H‐score >10) in 25 (78.1%) samples. The expression levels of SHP2 and pSHP2 were positively correlated. Stromal SHP2 (s‐SHP2) was higher in tumors with PD‐L1 ≥50% versus PD‐L1 <50% (p = 0.039). By quantitative mIFC analysis, the expression of s‐SHP2 had positive correlation with CD8, CD4, CD68, and PD‐L1 levels in stromal area. Patients with high SHP2 expression made up 100.0% of the partial respond (PR) and 80.0% of the stable disease (SD), whereas 50.0% of the progress disease (PD). High SHP2 expression was associated with longer progression‐free survival (PFS) and overall survival (OS) (p < 0.001, p = 0.013). Patients with high expression of both SHP2 and PD‐L1 had longer PFS (p < 0.001). Conclusion: High SHP2 expression could predict the efficacy of immunotherapy and better survival in advanced KRAS mutant NSCLC. SHP2 may function in both tumor cells and immune cells, warranting further study on the potential diverse effects of SHP2 inhibition in TME. [ABSTRACT FROM AUTHOR]

Aim Evasion of apoptosis is a hallmark of human cancer cells. We sought to explore the potential synergistic antitumor activity and underlying mechanisms of the pro-apoptotic agent PAC-1 plus cisplatinum (Cis) in non-small cell lung cancer ( NSCLC) cell lines. Methods The adenocarcinoma cell lines H1299, A549, PC9, H1650 and H1975 were used as in vitro models. Colorimetric MTT assays, Western blotting and flow cytometry were used to evaluate the anti-growth effects of PAC-1 and/or Cis and apoptosis status. The activated form of CASP3 ( C-CASP3) was assessed by immunofluorescent staining. Results Single-agent Cis and PAC-1 were able to inhibit the cancer cell growth in certain dose ranges, with IC50 values of 1.9-11.7 and 5.6-14.8 μM, respectively. Sequential Cis→ PAC-1 or concurrent Cis + PAC-1, but not PAC-1→Cis combinations showed synergistic effects on cell growth inhibition in H1299 cells (combination index, CI ≤ 0.6). In contrast, other combination modes mostly showed seemingly antagonistic effects (CI > 1.0). Flow cytometric analysis showed that Cis→ PAC-1 sequential combination showed strong pro-apoptotic effects in H1299 cells. Western blots showed that in H1299, PC9 and H1975 cells, PAC-1 promoted the C-CASP3, but only in H1299 cells was there a synergistic effect with Cis on the CASP3 activation. Conclusions PAC-1 showed anti-tumor activity in NSCLCs in vitro and a synergistic effect with cisplatin in EGFRwt KRASwt H1299 cells. Our data suggest a potential treatment approach using cisplatin plus a pro-apoptotic agent acting via CASP3 activation for this subgroup of pulmonary adenocarcinomas. [ABSTRACT FROM AUTHOR]