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Abstract Background Conquering acquired resistance to osimertinib remains a major challenge in treating patients with epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC). Thus, we aimed to determine the safety and efficacy of combination treatment with osimertinib and afatinib for patients with acquired resistance to osimertinib. Methods This open-label phase I study was a feasibility study of the combination of afatinib and osimertinib for patients with advanced EGFR-positive NSCLC who had progressive disease after receiving osimertinib. The primary endpoint was to determine the maximum tolerated dose (MTD). We enrolled patients who received afatinib at three different dose levels (level 1, 20 mg; level 2, 30 mg; level 3, 40 mg) combined with osimertinib at a standard dose of 80 mg once per day. Results Thirteen patients were enrolled in this study. The MTD was defined as 30 mg afatinib when combined with daily oral administration of osimertinib (80 mg). The most frequent adverse events were diarrhea (76.9%), anemia (76.9%), and rash (69.2%). Considering the toxicity profiles during all treatment periods, the recommended oral dose of afatinib was determined as 20 mg daily, with an osimertinib dose of 80 mg. For all evaluable patients (n = 12), the response rate was 7.7% and the disease-control rate was 46.2%. Conclusion Combination therapy with osimertinib and afatinib was tolerable; however, the synergistic effect of afatinib with osimertinib may be limited in osimertinib-resistant patients. Trial registration Japan Registry of Clinical Trials ID: jRCTs051180008, registered date: 08/11/2018.

Abstract Multiple primary lung cancers (MPLCs) harbour various genetic profiles among the tumours, even from individuals with same non-intrinsic risk factors. Paired mutational analyses were performed to obtain a census of mutational events in MPLC and assess their relationship with non-intrinsic risk factors. Thirty-eight surgical specimens from 17 patients diagnosed as MPLC were used. Extracted DNAs were sequenced for somatic mutations in 409 cancer-associated genes from a comprehensive cancer panel. We statistically analysed the correlation between each driver mutation frequency and non-intrinsic risk factors using Fisher's exact test, and whether genetic mutations occurred concomitantly or randomly in MPLC using an exact test. Comprehensive genetic analyses suggested different mutation profiles in tumours within the same individuals, with some exceptions. EGFR, KRAS, TP53, or PARP1 mutations were concomitantly detected in some MPLC cases. EGFR mutations were significantly more frequent in never or light smokers and females. Concomitant EGFR or KRAS mutations in MPLCs were significantly more frequent than expected by chance (P = .0023 and .0049, respectively) suggesting a more prominent role of non-intrinsic risk factors in EGFR and KRAS mutations than other mutations, which occurred more randomly. Concomitant EGFR or KRAS mutations were particularly prominent in never or light smokers and males.

Introduction: Multiple primary lung cancers (MPLCs) occur in common carcinogenetic risks such as lifestyle, biological aging, immune responses, hormones, and metabolism. Although MPLCs harbor various genetic profiles within the same individuals, differences in the tumor microenvironment (TME) are unclear. We investigated the impact of genetic aberrations, non-intrinsic factors, and pathological subtypes on tumor immunity. Materials and Methods: In total, 73 surgically resected specimens from 32 patients with MPLC were analyzed. PD-L1 expression in tumor cells (TCs) and immune cells (ICs), CD3-positive tumor-infiltrating lymphocytes (TILs), CD8/CD3 ratios, and FOXP3-positive TILs that compose TMEs were evaluated by immunohistochemistry and classified on a score of 0–2. 38 tumors were sequenced for somatic mutations in 409 cancer-associated genes. Results: Females and never or light smokers had a higher incidence of PD-L1-negative tumors and a higher concordance rate. PD-L1 positivity in TCs and ICs was significantly less frequent in EGFR-mutated than in wild-type tumors. Differences in the score of TMEs were observed between the KRAS-mutated-only tumor and the KRAS and TP53-co-mutated tumors, and between the KRAS-mutated-only tumor and the KRAS and STK11-co-mutated tumors. Significantly more FOXP3-high TILs were observed in invasive pathological subtypes than in non-invasive ones. Conclusion: Comparing TMEs among MPLCs revealed that non-smokers or light smokers and females were unlikely to express PD-L1 regardless of tumor site and confirmed that the EGFR mutations and co-occurring KRAS and STK11 or TP53 mutations were associated with TME. Pathological subtypes may impact the efficacy of immune therapy due to their potential correlations with regulatory T cells.

Epithelial-mesenchymal transition (EMT) is a crucial event in tumor invasion and metastasis. However, most of past EMT studies have been conducted in the conventional two-dimensional (2D) monolayer culture. Therefore, it remains unclear what invasive phenotypes are acquired by EMT-induced cancer cells. To address this point, we attempted to characterize EMT cells in more physiological, three-dimensional (3D) collagen gel culture. EMT was induced by treating three human carcinoma cell lines (A549, Panc-1 and MKN-1) with TGF-ß. The TGF-ß treatment stimulated these cells to overexpress the invasion markers laminin γ2 and MT1-MMP in 2D culture, in addition to the induction of well-known morphological change and EMT marker expression. EMT induction enhanced cell motility and adhesiveness to fibronectin and collagen in 2D culture. Although EMT cells showed comparable cell growth to control cells in 2D culture, their growth rates were extremely suppressed in soft agar and collagen gel cultures. Most characteristically, EMT-induced cancer cells commonly and markedly extended invasive protrusions in collagen gel. These protrusions were mainly supported by microtubules rather than actin cytoskeleton. Snail-introduced, stable EMT cells showed similar protrusions in 3D conditions without TGF-ß. Moreover, these protrusions were suppressed by colchicine or inhibitors of heat shock protein 90 (HSP-90) and protein phosphatase 2A. However, MMP inhibitors did not suppress the protrusion formation. These data suggest that EMT enhances tumor cell infiltration into interstitial stroma by extending microtubule-based protrusions and suppressing cell growth. The elevated cell adhesion to fibronectin and collagen and high cell motility also seem important for the tumor invasion.

Interaction between tumor cells and stromal fibroblasts plays essential roles in tumor progression. However, its detailed molecular mechanism remains unclear. To understand the mechanism, we investigated molecules mediating this interaction using the three-dimensional (3D) co-culture system of Panc-1 pancreatic carcinoma cells with normal fibroblasts. When the two kinds of cells were placed on the top of collagen gel, the tumor cells scattered into the fibroblast layer, apparently undergoing epithelial-mesenchymal transition. When fibroblasts were placed within collagen gel, Panc-1 cells actively invaded into the collagen gel, extending a microtubule-based long protrusion. Although transforming growth factor-β (TGF-β) and hepatocyte growth factor (HGF) individually stimulated the tumor cell invasion into collagen gel without fibroblasts, TGF-β signaling inhibitors (SB431542 and LY2157299) significantly enhanced the Panc-1 cell invasion in the 3D co-culture with fibroblasts. Experiments with HGF/Met signaling inhibitors or with the fibroblast conditioned medium revealed that HGF was a major invasion-promoting factor secreted from fibroblasts and SB431542 increased the HGF secretion by blocking the HGF-suppressing activity of cancer cell-derived TGF-β. These results indicate that HGF and TGF-β are critical regulators for both tumor-stroma interaction and tumor invasion. The results also suggest that TGF-β signaling inhibitors may promote tumor progression under some pathological conditions. [ABSTRACT FROM AUTHOR]