TP53 gain-of-function mutations promote osimertinib resistance via TNF-α-NF-κB signaling in EGFR-mutated lung cancer.

EGFR tyrosine kinase inhibitors (TKIs) are effective against EGFR-mutated lung cancer, but tumors eventually develop resistance to these drugs. Although TP53 gain-of-function (GOF) mutations promote carcinogenesis, their effect on EGFR-TKI efficacy has remained unclear. We here established EGFR-mutated lung cancer cell lines that express wild-type (WT) or various mutant p53 proteins with CRISPR-Cas9 technology and found that TP53-GOF mutations promote early development of resistance to the EGFR-TKI osimertinib associated with sustained activation of ERK and expression of c-Myc. Gene expression analysis revealed that osimertinib activates TNF-α-NF-κB signaling specifically in TP53-GOF mutant cells. In such cells, osimertinib promoted interaction of p53 with the NF-κB subunit p65, translocation of the resulting complex to the nucleus and its binding to the TNF promoter, and TNF-α production. Concurrent treatment of TP53-GOF mutant cells with the TNF-α inhibitor infliximab suppressed acquisition of osimertinib resistance as well as restored osimertinib sensitivity in resistant cells in association with attenuation of ERK activation and c-Myc expression. Our findings indicate that induction of TNF-α expression by osimertinib in TP53-GOF mutant cells contributes to the early development of osimertinib resistance, and that TNF-α inhibition may therefore be an effective strategy to overcome such resistance in EGFR-mutant lung cancer with TP53-GOF mutations.

Regulation of PD-L1 expression in non-small cell lung cancer by interleukin-1ß.

Introduction: Programmed cell death-ligand 1 (PD-L1) is a biomarker for prediction of the clinical efficacy of immune checkpoint inhibitors in various cancer types. The role of cytokines in regulation of PD-L1 expression in tumor cells has not been fully characterized, however. Here we show that interleukin-1ß (IL-1ß) plays a key role in regulation of PD-L1 expression in non-small cell lung cancer (NSCLC). Methods: We performed comprehensive screening of cytokine gene expression in NSCLC tissue using available single-cell RNA-Sequence data. Then we examined the role of IL-1ß in vitro to elucidate its induction of PD-L1 on NSCLC cells. Results: The IL-1ß gene is highly expressed in the tumor microenvironment, particularly in macrophages. The combination of IL-1ß and interferon-γ (IFN-γ) induced a synergistic increase in PD-L1 expression in NSCLC cell lines. IL-1ß and IFN-γ also cooperatively activated mitogen-activated protein kinase (MAPK) signaling and promoted the binding of downstream transcription factors to the PD-L1 gene promoter. Furthermore, inhibitors of MAPK signaling blocked upregulation of PD-L1 by IL-1ß and IFN-γ. Discussion: Our study reports high levels of IL-1ß in the tumor microenvironment may cooperate with IFN-γ to induce maximal PD-L1 expression in tumor cells via activation of MAPK signaling, with the IL-1ß-MAPK axis being a promising therapeutic target for attenuation of PD-L1-mediated suppression of antitumor immunity.

Impact of increased plasma levels of calreticulin on prognosis of patients with advanced lung cancer undergoing combination treatment of chemotherapy and immune checkpoint inhibitors.

BACKGROUND: Damage-associated molecular pattern (DAMP)-related immunogenic cell death triggers secondary adaptive immune responses. The relationship between DAMP levels and prognosis in patients with non-small cell lung cancer (NSCLC) who undergo a combination therapy of immune checkpoint inhibitors (ICI) and chemotherapy remains unclear. METHODS: Serial plasma samples were prospectively collected from 45 patients treated with ICI combination therapy for advanced NSCLC. Plasma concentrations of high-mobility group box 1 (HMGB1), calreticulin (CRT), annexin A1, and heat shock protein 70 were measured. Associations between increases in plasma DAMP levels and the efficacy of the ICI combination therapy were evaluated. RESULTS: The maximum fold changes in plasma levels differed across individuals but demonstrated a marked increase, especially for CRT (mean ± SEM, 11.61 ± 46.15). Increased plasma DAMP levels were not clearly associated with clinical responses. There was a significant correlation between the maximum fold change in CRT levels and progression-free survival (PFS; r = 0.49, P < 0.001). Median PFS and overall survival (OS) rates were higher in patients with a ≥ 2-fold increase in plasma CRT levels than in those with a < 2-fold increase (PFS, 14.9 versus 6.0 months, hazard ratio (HR), 0.58; P = 0.17; OS, not reached versus 21.6 months, HR, 0.31, P = 0.02). CONCLUSIONS: Plasma CRT level monitoring has the potential to predict the efficacy of ICI combination therapy and shed light on the mechanisms underlying DAMP-related immunogenic cell death.

Mutant forms of EGFR promote HER2 trafficking through efficient formation of HER2-EGFR heterodimers.

INTRODUCTION: Human epidermal growth factor receptor 2 (HER2) forms homodimers and is retained at the surface of cancer cells positive for HER2 amplification. The dimerization, internalization, and intracellular trafficking of HER2 in cancer cells without HER2 amplification have remained uncharacterized, however. MATERIALS AND METHODS: HER2 homodimers and heterodimers were detected in various cell lines with the use of an in situ proximity ligation assay. The effects of wild-type or mutant forms of epidermal growth factor receptor (EGFR) on intracellular trafficking of HER2 were examined by live-cell imaging. The sensitivity of cell lines without HER2 amplification to ado-trastuzumab emtansine (T-DM1), an anti-HER2 (trastuzumab)-cytotoxic drug conjugate (ADC) was also investigated. RESULTS: HER2 preferentially formed heterodimers with EGFR rather than homodimers and was rapidly internalized together with EGFR in cells without HER2 amplification. HER2-EGFR heterodimers were more abundant and HER2 was more efficiently transferred to lysosomes in such cells with than in those without EGFR activating mutations. T-DM1 showed a high cytotoxic efficacy in the cells with EGFR mutations, suggesting that mutant forms of EGFR promote the transfer of HER2-bound T-DM1 to lysosomes through efficient formation of HER2-EGFR heterodimers. CONCLUSION: Our findings reveal that HER2 trafficking is affected by EGFR, especially by mutant forms of the receptor, and they provide a rationale for the use of HER2-targeting ADCs in the treatment of EGFR-mutated lung cancer.

Increased plasma levels of damage-associated molecular patterns during systemic anticancer therapy in patients with advanced lung cancer.

BACKGROUND: Immunogenic cell death (ICD) characterized by the release of damage-associated molecular patterns (DAMPs) from dying cancer cells may contribute to the synergistic antitumor effect of cytotoxic chemotherapy combined with an immune checkpoint inhibitor. The kinetics of circulating DAMP levels in cancer patients have remained largely uncharacterized, however. METHODS: We evaluated the possible effects of various systemic anticancer therapy modalities on the kinetics of plasma DAMP concentrations in a prospective observational study of patients with advanced lung cancer. The plasma concentrations of high-mobility group box 1 (HMGB1), calreticulin (CRT), heat shock protein 70 (HSP70), annexin A1, and histone H3 were thus determined in 121 such patients at four time points during the first cycle of treatment. RESULTS: The mean of the maximum fold change in HMGB1, HSP70, or annexin A1 concentration observed during treatment was significantly greater than the corresponding baseline value (P<0.005). The maximum fold changes in HMGB1 and CRT concentrations tended to be associated with clinical response as evaluated by RECIST criteria, although the changes in the levels of these two DAMPs were not correlated, suggestive of differential induction mechanisms. Among the various treatment modalities administered, platinum-based combination or single-agent chemotherapy tended to elicit robust increases in the concentrations of HMGB1 and CRT. CONCLUSIONS: Serial monitoring of plasma revealed that systemic anticancer therapy increased the circulating levels of HMGB1 and CRT and that these changes tended to be associated with clinical response, suggesting that agents capable of releasing these DAMPs into plasma might induce ICD in advanced lung cancer patients.

Cytotoxic chemotherapeutic agents and the EGFR-TKI osimertinib induce calreticulin exposure in non-small cell lung cancer.

OBJECTIVES: Synergistic anticancer efficacy of combination treatment with immune checkpoint inhibitors (ICIs) and platinum-based chemotherapy in patients with advanced non-small cell lung cancer (NSCLC) may be attributable in part to the phenomenon of immunogenic cell death (ICD), which is characterized by the release of damage-associated molecular patterns (DAMPs) from dying tumor cells. The ability of cytotoxic chemotherapeutic agents and molecularly targeted drugs such as epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) to induce DAMPs during the treatment of NSCLC has remained unclear, however. MATERIALS AND METHODS: We investigated the ability of seven cytotoxic chemotherapeutic agents and the third-generation EGFR-TKI osimertinib to induce translocation of the DAMP calreticulin to the cell surface in multiple NSCLC cell lines. The plasma concentration of soluble CRT in advanced NSCLC patients treated with cytotoxic chemotherapy or osimertinib was measured. RESULTS: Antimetabolites and microtubule inhibitors induced expression of CRT at the cell surface (ecto-CRT) to a greater extent than did platinum agents in six NSCLC cell lines, exhibiting higher up-regulation of phosphorylation of eukaryotic initiation factor-2α (eIF2α). Ecto-CRT expression was positively correlated with apoptosis induction in NSCLC cells treated with these various chemotherapeutic agents. The drug-induced up-regulation of ecto-CRT in NSCLC cells was attenuated by the pan-caspase inhibitor Z-VAD-FMK. Osimertinib similarly increased ecto-CRT expression in association with apoptosis induction in five EGFR-mutated NSCLC cell lines. Furthermore, the plasma concentration of soluble CRT in 16 NSCLC patients treated with single-agent pemetrexed or docetaxel and in nine EGFR-mutated NSCLC patients treated with osimertinib was increased after treatment onset. CONCLUSION: Our findings indicate that antimetabolites, microtubule inhibitors, and osimertinib are effective inducers both of CRT exposure in NSCLC cell lines and of soluble CRT release in patients with advanced NSCLC, suggesting that these agents might prove effective for promotion of antitumor immunity in combination immunotherapy.