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Background Bevacizumab in combination with chemotherapeutics has shown significant survival benefit in clinical studies in patients with non-small cell lung cancer (NSCLC). Since bevacizumab was administered as standard treatment until disease progression, the importance of bevacizumab during the maintenance phase was not prospectively investigated in these studies. Materials and methods Three human NSCLC cell line xenograft models were used to investigate antitumor effect of bevacizumab and tumor microvessel density (MVD) was analyzed. Results In A549 and NCI-H292 models, bevacizumab maintenance following combination with paclitaxel exhibited stronger tumor suppression than its absence. In an NCI-H292 model, bevacizumab maintenance continuously inhibited increase of MVD. In an NCI-H2228 model following induction treatment with pemetrexed and bevacizumab, maintenance with pemetrexed plus bevacizumab, had stronger efficacy than pemetrexed alone and led to lower MVD and level of thymidylate synthase. Conclusion Continuous suppression of angiogenesis by bevacizumab may contribute to the superior efficacy of maintenance treatment containing bevacizumab.

Background Immune checkpoint inhibitors have marked antitumor effect. However, monotherapy benefits only a limited population of patients, and further improvement of their effects is required. Here the therapeutic effect and immune response during anti-PD-L1 plus cisplatin combination therapy were investigated in a mouse model. Materials and methods E.G7-OVA, expressing ovalbumin (OVA) gene as a model tumor antigen, was subcutaneously inoculated into syngeneic mice and treated with anti-PD-L1 with/without cisplatin. The tumor growth and activation status of immune cells were evaluated. Results The anti-PD-L1 plus cisplatin combination resulted in a potent antitumor effect leading to tumor shrinkage compared to anti-PD-L1 or cisplatin alone, even though each alone, significantly inhibited tumor growth compared to the control group. During treatment, all groups, including that treated with cisplatin alone, had increased CD8+ T-cell infiltration into tumor tissues compared with the control group, and the therapeutic effect was diminished by CD8+ cell depletion. Aside from its direct cytotoxic effect, cisplatin alone increased chemokine levels and expression of immune checkpoint molecules on CD8+ T-cells in the tumor site. The combination effectively activated OVA-specific CD8+ T-cells. Furthermore, anti-PD-L1 alone and in combination with cisplatin, but not cisplatin alone, induced interferon-gamma-producing CD4+ T-cells. Conclusion These findings provide a rationale for anti-PD-L1 plus cisplatin becoming a promising combination therapy for patients with cancer.

Epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are common in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). The aim of the present study was to develop a simple and versatile tool to determine EGFR and KRAS mutations for pre-clinical research in the laboratory. We developed a melting curve analysis to detect exon 19 deletion, L858R mutation, and T790M mutation of EGFR, and codon 12/13 and codon 61 mutations of KRAS using LightCycler480 with mutation-specific sensor and anchor probes. The analytical method was applicable to determine the approximate rate of heterogeneity of mutation in the genomic DNA of cancer cell lines. In conclusion, our melting curve analysis is a rapid and semi-quantitative method to screen for exon 19 deletion, L858R or T790M mutations of EGFR and codon 12/13/61 mutations of KRAS in cancer cell lines.