Background The clinical efficacy observed with inhibitors of programed cell death 1/programed cell death ligand 1 (PD-L1/PD-1) in cancer therapy has prompted studies to characterize the immune response in several tumor types, including lung cancer. However, the immunological profile of non–small cell lung carcinoma (NSCLC) treated with neoadjuvant chemotherapy (NCT) is not yet fully characterized, and it may be therapeutically important. The aim of this retrospective study was to characterize and quantify PD-L1/PD-1 expression and tumor-associated immune cells (TAICs) in surgically resected NSCLCs from patients who received NCT or did not receive NCT (non-NCT). Methods We analyzed immune markers in formalin-fixed, paraffin-embedded tumor tissues resected from 112 patients with stage II/III NSCLC, including 61 non-NCT (adenocarcinoma [ADC] = 33; squamous cell carcinoma [SCC] = 28) and 51 NCT (ADC = 31; SCC = 20). We used multiplex immunofluorescence to identify and quantify immune markers grouped into two 6-antibody panels: panel 1 included AE1/AE3, PD-L1, CD3, CD4, CD8, and CD68; panel 2 included AE1/AE3, PD1, granzyme B, FOXP3, CD45RO, and CD57. Results PD-L1 expression was higher (> overall median) in NCT cases (median, 19.53%) than in non-NCT cases (median, 1.55%; P = 0.022). Overall, density of TAICs was higher in NCT-NSCLCs than in non-NCT-NSCLCs. Densities of CD3+ cells in the tumor epithelial compartment were higher in NCT-ADCs and NCT-SCCs than in non-NCT-ADCs and non-NCT-SCCs (P = 0.043). Compared with non-NCT-SCCs, NCT-SCCs showed significantly higher densities of CD3 + CD4+ (P = 0.019) and PD-1+ (P < 0.001) cells in the tumor epithelial compartment. Density of CD68+ tumor-associated macrophages (TAMs) was higher in NCT-NSCLCs than in non-NCT-NSCLCs and was significantly higher in NCT-SCCs than in non-NCT-SCCs. In NCT-NSCLCs, higher levels of epithelial T lymphocytes (CD3 + CD4+) and epithelial and stromal TAMs (CD68+) were associated with better outcome in univariate and multivariate analyses. Conclusions NCT-NSCLCs exhibited higher levels of PD-L1 expression and T-cell subset regulation than non-NCT-NSCLCs, suggesting that NCT activates specific immune response mechanisms in lung cancer. These results suggest the need for clinical trials and translational studies of combined chemotherapy and immunotherapy prior to surgical resection of locally advanced NSCLC.

Despite substantial advances in targeting mutant KRAS, tumor resistance to KRAS inhibitors (KRASi) remains a major barrier to progress. Here, we report proteostasis reprogramming as a key convergence point of multiple KRASi-resistance mechanisms. Inactivation of oncogenic KRAS down-regulated both the heat shock response and the inositol-requiring enzyme 1α (IRE1α) branch of the unfolded protein response, causing severe proteostasis disturbances. However, IRE1α was selectively reactivated in an ER stress–independent manner in acquired KRASi-resistant tumors, restoring proteostasis. Oncogenic KRAS promoted IRE1α protein stability through extracellular signal–regulated kinase (ERK)–dependent phosphorylation of IRE1α, leading to IRE1α disassociation from 3-hydroxy-3-methylglutaryl reductase degradation (HRD1) E3-ligase. In KRASi-resistant tumors, both reactivated ERK and hyperactivated AKT restored IRE1α phosphorylation and stability. Suppression of IRE1α overcame resistance to KRASi. This study reveals a druggable mechanism that leads to proteostasis reprogramming and facilitates KRASi resistance.

We have suggested that major pathologic response (MPR) could serve as a surrogate endpoint for survival and provide rapid means of comparing different neoadjuvant treatment regimens. Here, we confirm that MPR is predictive of long-term overall survival (OS) in patients with non-small-cell lung cancer (NSCLC) who underwent neoadjuvant chemotherapy and surgical resection, to assess agreement on MPR between 2 observers, and to determine the minimum number of slides needed to obtain an accurate determination of MPR. We identified 151 patients with NSCLC who had been treated with neoadjuvant chemotherapy followed by complete surgical resection from 2008 to 2012. Tissue specimens were retrospectively evaluated by 2 pathologists who had been blinded to patients' treatment and outcome. We assessed the relationships between MPR and OS, the levels of agreement between the pathologists, and determined the number of slides needed to obtain an accurate determination of MPR. Our results reveal that MPR examined by either observer 1 (experienced) or by observer 2 (trained) was significantly predictive of long-term OS after neoadjuvant chemotherapy. MPR was associated with long-term OS in patients with NSCLC undergoing neoadjuvant chemotherapy on multivariable analysis (hazard ratio 2.68; P = .01). The levels of agreement between 2 pathologists were high after direct in-person training by one pathologist or the other (R² = 0.994). Our data suggest that at least 3 slides should be read to accurately determine MPR. MPR is significantly predictive of long-term OS in neoadjuvant chemotherapy-treated patients with NSCLC. MPR may serve as a surrogate endpoint for evaluating novel chemotherapies and immunotherapy response in biomarker-driven translational clinical trials.

Major pathologic response (MPR), defined as residual viable tumor of less than or equal to 10%, currently serves as a surrogate end point for survival for patients with resectable NSCLC after neoadjuvant chemotherapy. However, the significance of pathologic response in lymph nodes harboring metastatic tumors in such patients remains uncertain. Therefore, we studied the effect of neoadjuvant chemotherapy on resected positive lymph nodes and determined if the degree of pathologic response in the lymph nodes alone (LN-MPR) or in combination with that of the primary tumor (PT-MPR) was able to predict the outcome. A total of 75 patients with NSCLC who underwent neoadjuvant chemotherapy and completed surgical resection were included in this study. Tissue specimens were retrospectively evaluated by two pathologists blinded to the patients' treatments and outcomes. Specimens were reviewed for the degree of pathologic response in the primary tumor and in any involved lymph nodes. The prognostic performance of LN-MPR alone or in combination with PT-MPR with respect to overall survival (OS) was evaluated using the Kaplan-Meier method and Cox regression model. LN-MPR was significantly predictive of long-term OS after neoadjuvant chemotherapy. A combination of PT-MPR with LN-MPR was significantly associated with outcome and allowed stratification of patients into three prognostic groups (p = 0.001). LN-MPR in isolation is a reliable predictor of OS in patients with NSCLC receiving neoadjuvant chemotherapy. A combination of LN-MPR with PT-MPR seems to correlate well with the outcome and can be used to predict prognosis in this patient population.