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Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), potently and selectively inhibits EGFR-TKI-sensitizing and EGFR T790M resistance mutations. In the Phase III FLAURA study (NCT02296125), first-line osimertinib improved outcomes vs comparator EGFR-TKIs in EGFRm advanced non-small cell lung cancer. This analysis identifies acquired resistance mechanisms to first-line osimertinib. Next-generation sequencing assesses circulating-tumor DNA from paired plasma samples (baseline and disease progression/treatment discontinuation) in patients with baseline EGFRm. No EGFR T790M-mediated acquired resistance are observed; most frequent resistance mechanisms are MET amplification ( n  = 17; 16%) and EGFR C797S mutations ( n  = 7; 6%). Future research investigating non-genetic acquired resistance mechanisms is warranted. In the phase III FLAURA study (NCT02296125), the third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) osimertinib provided superior progression-free survival versus comparator EGFR-TKIs in patients with NSCLC. Here, by next-generation sequencing of circulating tumor DNA, the authors assess candidate mechanisms of acquired resistance to first-line osimertinib in patients from the FLAURA trial.

Cisplatin is one of the most effective and widely used anticancer agents for the treatment of several types of tumors. The cytotoxic effect of cisplatin is thought to be mediated primarily by the generation of nuclear DNA adducts, which, if not repaired, cause cell death as a consequence of DNA replication and transcription blockage. However, the ability of cisplatin to induce nuclear DNA (nDNA) damage per se is not sufficient to explain its high degree of effectiveness nor the toxic effects exerted on normal, post-mitotic tissues. Oxidative damage has been observed in vivo following exposure to cisplatin in several tissues, suggesting a role for oxidative stress in the pathogenesis of cisplatin-induced dose-limiting toxicities. However, the mechanism of cisplatin-induced generation of ROS and their contribution to cisplatin cytotoxicity in normal and cancer cells is still poorly understood. By employing a panel of normal and cancer cell lines and the budding yeast Saccharomyces cerevisiae as model system, we show that exposure to cisplatin induces a mitochondrial-dependent ROS response that significantly enhances the cytotoxic effect caused by nDNA damage. ROS generation is independent of the amount of cisplatin-induced nDNA damage and occurs in mitochondria as a consequence of protein synthesis impairment. The contribution of cisplatin-induced mitochondrial dysfunction in determining its cytotoxic effect varies among cells and depends on mitochondrial redox status, mitochondrial DNA integrity and bioenergetic function. Thus, by manipulating these cellular parameters, we were able to enhance cisplatin cytotoxicity in cancer cells. This study provides a new mechanistic insight into cisplatin-induced cell killing and may lead to the design of novel therapeutic strategies to improve anticancer drug efficacy.

Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), potently and selectively inhibits EGFR-TKI-sensitizing and EGFR T790M resistance mutations. This analysis evaluates acquired resistance mechanisms to second-line osimertinib (n = 78) in patients with EGFR T790M advanced non-small cell lung cancer (NSCLC) from AURA3 (NCT02151981), a randomized phase 3 study comparing osimertinib with chemotherapy. Plasma samples collected at baseline and disease progression/treatment discontinuation are analyzed using next-generation sequencing. Half (50%) of patients have undetectable plasma EGFR T790M at disease progression and/or treatment discontinuation. Fifteen patients (19%) have >1 resistance-related genomic alteration; MET amplification (14/78, 18%) and EGFR C797X mutation (14/78, 18%). In the phase III AURA3 study (NCT02151981), the third-generation epidermal growth factor receptor tyrosine kinase inhibitor osimertinib prolonged progression-free survival versus platinum-doublet chemotherapy in patients with EGFR T790M advanced NSCLC. Here, by next-generation sequencing of circulating tumor DNA, the authors assess candidate mechanisms of acquired resistance to osimertinib in patients from the AURA3 trial.

Approximately 1.6 million new cases of lung cancer are diagnosed each year throughout the world. In many countries, the mortality related to lung cancer continues to rise. The outcomes for patients with all stages of lung cancer have improved in recent years. The use of systemic therapy in conjunction with local therapy has led to improved cure rates in both resectable and unresectable patient groups. For patients with advanced stage disease, modest but real improvements in overall survival and quality of life have been achieved with systemic chemotherapy. A major focus of research has been the development of molecularly targeted agents and the identification of biomarkers for patient selection. Patients with non-small cell lung cancer with mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain achieve response rates of greater than 70% and superior progression-free survival when treated with an EGFR tyrosine kinase inhibitor compared with standard chemotherapy. This has now emerged as the preferred therapeutic approach for the subset of patients with a mutation in exons 19 or 21 of the EGFR. Another promising targeted approach involves the use of an anaplastic lymphoma kinase (ALK) inhibitor in patients with a translocation involving the echinoderm microtubule-associated protein-like 4 (EML4) and -ALK genes. Finally, a paradigm shift in favor of maintenance therapy for patients with advanced stage disease has gained strength from recent data. All of these advances have been made possible by developing a greater understanding of the biology, the discovery of novel anticancer agents, and improved supportive care measures. This article reviews the major strides made in the treatment of lung cancer in the recent past. [PUBLICATION ABSTRACT]

T cell exhaustion is a state of T cell dysfunction associated with expression of programmed death 1 (PD-1). Exhausted CD8+ T cells are maintained by self-renewing stem-like T cells that provide differentiated TIM3+ cells, a part of which possesses effector-like properties. PD-1-targeted therapies enhance T cell response by promoting differentiation of stem-like T cells toward TIM3+ cells, but the role of mTOR during T cell exhaustion remains elusive. Here, we showed that mTOR inhibition has distinct outcomes during the beginning of and after the establishment of chronic viral infection. Blocking mTOR during the T cell expansion phase enhanced the T cell response by causing accumulation of stem-like T cells, leading to improved efficacy of PD-1 immunotherapy; whereas, after exhaustion progressed, mTOR inhibition caused immunosuppression, characterized by decreased TIM3+ cells and increased viral load with minimal changes in stem-like T cells. Mechanistically, a cell-intrinsic mTOR signal was vital for differentiation of stem-like T cells into the TIM3+ state in the early and late phases of chronic infection as well as during PD-1 immunotherapy. Thus, PD-1 blockade worked after cessation of mTOR inhibition, but simultaneous treatment failed to induce functional TIM3+ cells, reducing efficacy of PD-1 immunotherapy. Our data demonstrate that mTOR regulates T cell exhaustion and have important implications for combination cancer therapies with PD-1 blockade.

AZD9291, an irreversible inhibitor of epidermal growth factor receptor, was associated with tumor responses in the majority of patients with advanced non–small-cell lung cancer in whom T790M-mediated drug resistance to other EGFR tyrosine kinase inhibitors had developed. Somatic mutations in the gene encoding epidermal growth factor receptor ( EGFR ) are detected in approximately 30 to 40% of non–small-cell lung cancers (NSCLCs) from Asian patients and in 10% of NSCLCs from white patients. 1 – 3 EGFR mutations lead to constitutive activation of EGFR signaling and oncogenic transformation both in vitro and in vivo. 4 , 5 Cancers with EGFR mutations ( EGFR- mutated cancers) depend on EGFR signaling for growth and survival and are often sensitive to treatment with EGFR tyrosine kinase inhibitors. 6 Among patients with advanced EGFR- mutated NSCLC, treatment with EGFR tyrosine kinase inhibitors (e.g., gefitinib, erlotinib, and . . .

Phase 3 clinical data has shown higher proportions of patients with objective response, longer response duration, and longer overall survival with nivolumab versus docetaxel in patients with previously treated advanced non-small-cell lung cancer (NSCLC). We aimed to evaluate the long-term benefit of nivolumab and the effect of response and disease control on subsequent survival. We pooled data from four clinical studies of nivolumab in patients with previously treated NSCLC (CheckMate 017, 057, 063, and 003) to evaluate survival outcomes. Trials of nivolumab in the second-line or later setting with at least 4 years follow-up were included. Comparisons of nivolumab versus docetaxel included all randomised patients from the phase 3 CheckMate 017 and 057 studies. We did landmark analyses by response status at 6 months to determine post-landmark survival outcomes. We excluded patients who did not have a radiographic tumour assessment at 6 months. Safety analyses included all patients who received at least one dose of nivolumab. Across all four studies, 4-year overall survival with nivolumab was 14% (95% CI 11–17) for all patients (n=664), 19% (15–24) for those with at least 1% PD-L1 expression, and 11% (7–16) for those with less than 1% PD-L1 expression. In CheckMate 017 and 057, 4-year overall survival was 14% (95% CI 11–18) in patients treated with nivolumab, compared with 5% (3–7) in patients treated with docetaxel. Survival subsequent to response at 6 months on nivolumab or docetaxel was longer than after progressive disease at 6 months, with hazard ratios for overall survival of 0·18 (95% 0·12–0·27) for nivolumab and 0·43 (0·29–0·65) for docetaxel; for stable disease versus progressive disease, hazard ratios were 0·52 (0·37–0·71) for nivolumab and 0·80 (0·61–1·04) for docetaxel. Long-term data did not show any new safety signals. Patients with advanced NSCLC treated with nivolumab achieved a greater duration of response compared with patients treated with docetaxel, which was associated with a long-term survival advantage. Bristol-Myers Squibb.

Development of effective strategies to manage the inevitable acquired resistance to osimertinib, a third-generation EGFR inhibitor for the treatment of EGFR-mutant (EGFRm) non–small cell lung cancer (NSCLC), is urgently needed. This study reports that DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide, synergistically decreased cell survival, with enhanced induction of DNA damage and apoptosis in osimertinib-resistant cells; suppressed the growth of osimertinib-resistant tumors; and delayed the emergence of osimertinib-acquired resistance. Mechanistically, osimertinib decreased Topo IIα levels in EGFRm NSCLC cells by facilitating FBXW7-mediated proteasomal degradation, resulting in induction of DNA damage; these effects were lost in osimertinib-resistant cell lines that possess elevated levels of Topo IIα. Increased Topo IIα levels were also detected in the majority of tissue samples from patients with NSCLC after relapse from EGFR tyrosine kinase inhibitor treatment. Enforced expression of an ectopic TOP2A gene in sensitive EGFRm NSCLC cells conferred resistance to osimertinib, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their susceptibility to osimertinib-induced DNA damage and apoptosis. Together, these results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of osimertinib against EGFRm NSCLC, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib.

Imaging techniques based on fluorescence and bioluminescence have been important tools in visualizing tumor progression and studying the effect of drugs and immunotherapies on tumor immune microenvironment in animal models of cancer. However, transgenic expression of foreign proteins may induce immune responses in immunocompetent syngeneic tumor transplant models and augment the efficacy of experimental drugs. In this study, we show that the growth rate of Lewis lung carcinoma (LL/2) tumors was reduced after transduction of tdTomato and luciferase (tdTomato/Luc) compared to the parental cell line. tdTomato/Luc expression by LL/2 cells altered the tumor microenvironment by increasing tumor-infiltrating lymphocytes (TILs) while inhibiting tumor-induced myeloid-derived suppressor cells (MDSCs). Interestingly, tdTomato/Luc expression did not alter the response of LL/2 tumors to anti-PD-1 and anti-CTLA-4 antibodies. These results suggest that the use of tdTomato/Luc-transduced cancer cells to conduct studies in immune competent mice may lead to cell-extrinsic tdTomato/Luc-induced alterations in tumor growth and tumor immune microenvironment that need to be taken into consideration when evaluating the efficacy of anti-cancer drugs and vaccines in immunocompetent animal models.

Ribonucleotide reductase (RNR) catalyzes the de novo synthesis of deoxyribonucleoside diphosphates (dNDPs) to provide dNTP precursors for DNA synthesis. Here, we report that acetylation and deacetylation of the RRM2 subunit of RNR acts as a molecular switch that impacts RNR activity, dNTP synthesis, and DNA replication fork progression. Acetylation of RRM2 at K95 abrogates RNR activity by disrupting its homodimer assembly. RRM2 is directly acetylated by KAT7, and deacetylated by Sirt2, respectively. Sirt2, which level peak in S phase, sustains RNR activity at or above a threshold level required for dNTPs synthesis. We also find that radiation or camptothecin-induced DNA damage promotes RRM2 deacetylation by enhancing Sirt2–RRM2 interaction. Acetylation of RRM2 at K95 results in the reduction of the dNTP pool, DNA replication fork stalling, and the suppression of tumor cell growth in vitro and in vivo. This study therefore identifies acetylation as a regulatory mechanism governing RNR activity. Ribonucleotide reductase (RNR) catalyzes the de novo synthesis of deoxyribonucleoside diphosphates to provide dNTP precursors for DNA synthesis. Here the authors show that the availability of dNTPs, DNA replication, and cellular proliferation, are modulated by acetylation and deacetylation of RRM2 by KAT7 and Sirt2 respectively.