A novel EGFR-tyrosine kinase inhibitor (TKI), osimertinib, has marked efficacy in patients with EGFR-mutated lung cancer. However, some patients show intrinsic resistance and an insufficient response to osimertinib. This study showed that osimertinib stimulated AXL by inhibiting a negative feedback loop. Activated AXL was associated with EGFR and HER3 in maintaining cell survival and inducing the emergence of cells tolerant to osimertinib. AXL inhibition reduced the viability of EGFR-mutated lung cancer cells overexpressing AXL that were exposed to osimertinib. The addition of an AXL inhibitor during either the initial or tolerant phases reduced tumor size and delayed tumor re-growth compared to osimertinib alone. AXL was highly expressed in clinical specimens of EGFR-mutated lung cancers and its high expression was associated with a low response rate to EGFR-TKI. These results indicated pivotal roles for AXL and its inhibition in the intrinsic resistance to osimertinib and the emergence of osimertinib-tolerant cells.

Purpose: Lung cancers with epidermal growth factor receptor (EGFR)-activating mutations show good clinical response to gefitinib and erlotinib, selective tyrosine kinase inhibitors (TKI) to EGFR, but these tumors invariably develop drug resistance. Host stromal cells have been found to have a considerable effect on the behavior of cancer cells. Little is known, however, about the role of host cells on the sensitivity of cancer cells to receptor TKIs. We have therefore assessed the effect of crosstalk between stromal cells and lung cancer cells harboring EGFR mutations on susceptibility to EGFR-TKIs. Experimental Design: We evaluated the gefitinib sensitivity of lung cancer cells with EGFR-activating mutations, PC-9 and HCC827, when cocultured with fibroblasts and coinjected into severe combined immunodeficient mice. We also examined the effect of lung cancer cells to fibroblast recruitment. Results: Both human fibroblast cell lines and primary cultured fibroblasts produced various levels of hepatocyte growth factor (HGF). Lung cancer cells markedly recruited fibroblasts. The lung cancer cells became resistant to EGFR-TKIs when cocultured in vitro with HGF-producing fibroblasts and coinjected into severe combined immunodeficient mice. Importantly, combined use of gefitinib plus anti-HGF antibody or the HGF antagonist, NK4, successfully overcame the fibroblast-induced EGFR-TKI resistance both in vitro and in vivo. Colocalization of fibroblasts and HGF was detected in both xenograft tumors in mouse model and lung cancer patient specimens. Conclusions: These findings indicate that crosstalk to stromal fibroblasts plays a critical role in lung cancer resistance to EGFR-TKIs and may be an ideal therapeutic target in lung cancer with EGFR-activating mutations. ( Lung cancer is the leading cause of cancer-related death worldwide, with non-small cell lung cancer (NSCLC) accounting for ∼80% of lung cancers. The median survival of patients with metastatic NSCLC treated with the most active combination of conventional chemotherapy agents is 8 to 10 months (1, 2). Therefore, recent therapeutic strategies for NSCLC have focused on the development of molecular targeted agents.Epidermal growth factor receptor (EGFR), a member of a family of closely related growth factor receptor tyrosine kinases, is expressed in a majority of NSCLCs and has been an attractive target for the development of therapeutic agents. Almost 90% of these somatic activating mutations in EGFR consist of inframe deletions in exon 19 and L858R point mutations in exon 21 (3, 4). These mutations induce oncogenic activity and are closely correlated with sensitivity to small-molecule EGFR tyrosine kinase inhibitors (TKI), such as gefitinib and erlotinib. These mutations are more frequently present in females than in males, in nonsmokers than in smokers, in East Asians than in other ethnic groups, and in adenocarcinomas than in other tumor types (5). Several prospective clinical trials have shown that 70% to 75% of patients with tumors harboring these mu...

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BIM (BCL2L11) is a BH3-only proapoptotic member of the Bcl-2 protein family. BIM upregulation is required for apoptosis induction by EGF receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI) in EGFRmutant forms of non-small cell lung cancer (NSCLC). Notably, a BIM deletion polymorphism occurs naturally in 12.9% of East Asian individuals, impairing the generation of the proapoptotic isoform required for the EGFR-TKIs gefitinib and erlotinib and therefore conferring an inherent drug-resistant phenotype. Indeed, patients with NSCLC, who harbored this host BIM polymorphism, exhibited significantly inferior responses to EGFR-TKI treatment than individuals lacking this polymorphism. In an attempt to correct this response defect in the resistant group, we investigated whether the histone deacetylase (HDAC) inhibitor vorinostat could circumvent EGFR-TKI resistance in EGFR-mutant NSCLC cell lines that also harbored the BIM polymorphism. Consistent with our clinical observations, we found that such cells were much less sensitive to gefitinib-induced apoptosis than EGFR-mutant cells, which did not harbor the polymorphism. Notably, vorinostat increased expression in a dose-dependent manner of the proapoptotic BH3 domain-containing isoform of BIM, which was sufficient to restore gefitinib death sensitivity in the EGFR mutant, EGFR-TKIresistant cells. In xenograft models, while gefitinib induced marked regression via apoptosis of tumors without the BIM polymorphism, its combination with vorinostat was needed to induce marked regression of tumors with the BIM polymorphism in the same manner. Together, our results show how HDAC inhibition can epigenetically restore BIM function and death sensitivity of EGFR-TKI in cases of EGFR-mutant NSCLC where resistance to EGFR-TKI is associated with a common BIM polymorphism. Cancer Res; 73(8); 2428-34. Ó2013 AACR.

Supplemental Digital Content is Available in the Text.Naldemedine treatment of opioid-induced constipation was well tolerated for 52 weeks, did not precipitate opioid withdrawal, and increased bowel movements and quality of life.

ObjectiveThis study evaluated the efficacy and safety of oral naldemedine 0.1 mg, 0.2 mg, or 0.4 mg once daily in patients who had opioid-induced constipation (OIC) and maintained a stable laxative regimen.MethodsThis four-week, phase 2b, randomized, double-blind placebo-controlled trial (clinicaltrials.gov identifier NCT01443403) enrolled patients on long-term opioid therapy for chronic noncancer pain with OIC. The primary efficacy end point was change in weekly spontaneous bowel movement (SBM) frequency from baseline to the last two weeks of treatment. Secondary end points included the proportion of SBM responders (patients with ≥3 SBMs/week and an increase of ≥1 SBM/week from baseline over the last 2 weeks of treatment). Safety parameters assessed included adverse events, effects on analgesia, and opioid withdrawal symptoms.ResultsOverall, 244 patients were randomized 1:1:1:1 to naldemedine 0.1 mg, 0.2 mg, 0.4 mg, or placebo. Baseline patient characteristics were comparable. Weekly SBM frequency was significantly higher with naldemedine 0.2 mg (3.37, P = 0.0014) and 0.4 mg (3.64, P = 0.0003), but not with 0.1 mg (1.98, P = 0.3504), vs placebo (1.42). The proportion of SBM responders was significantly higher with naldemedine 0.2 mg (71.2%, P = 0.0005) and 0.4 mg (66.7%, P = 0.003), but not with 0.1 mg (52.5%, P = 0.1461), vs placebo (39.3%). Treatment-emergent adverse events were generally mild to moderate in severity; incidences increased with naldemedine dose. No clinically meaningful changes in other safety parameters were observed.ConclusionNaldemedine 0.2 mg once daily is the optimal dose for future confirmatory trials in OIC.

Purpose: Cancer cell microenvironments, including host cells, can critically affect cancer cell behaviors, including drug sensitivity. Although crizotinib, a dual tyrosine kinase inhibitor (TKI) of ALK and Met, shows dramatic effect against EML4-ALK lung cancer cells, these cells can acquire resistance to crizotinib by several mechanisms, including ALK amplification and gatekeeper mutation. We determined whether microenvironmental factors trigger ALK inhibitor resistance in EML4-ALK lung cancer cells.Experimental Design: We tested the effects of ligands produced by endothelial cells and fibroblasts, and the cells themselves, on the susceptibility of EML4-ALK lung cancer cell lines to crizotinib and TAE684, a selective ALK inhibitor active against cells with ALK amplification and gatekeeper mutations, both in vitro and in vivo.Results: EML4-ALK lung cancer cells were highly sensitive to ALK inhibitors. EGF receptor (EGFR) ligands, such as EGF, TGF-a, and HB-EGF, activated EGFR and triggered resistance to crizotinib and TAE684 by transducing bypass survival signaling through Erk1/2 and Akt. Hepatocyte growth factor (HGF) activated Met/Gab1 and triggered resistance to TAE684, but not crizotinib, which inhibits Met. Endothelial cells and fibroblasts, which produce the EGFR ligands and HGF, respectively, decreased the sensitivity of EML4-ALK lung cancer cells to crizotinib and TAE684, respectively. EGFR-TKIs resensitized these cells to crizotinib and Met-TKI to TAE684 even in the presence of EGFR ligands and HGF, respectively.Conclusions: Paracrine receptor activation by ligands from the microenvironment may trigger resistance to ALK inhibitors in EML4-ALK lung cancer cells, suggesting that receptor ligands from microenvironment may be additional targets during treatment with ALK inhibitors. Clin Cancer Res; 18(13); 3592-602. Ó2012 AACR.

High-level HGF expression was detected more frequently than EGFR T790M secondary mutation or MET amplification in tumors with intrinsic and acquired EGFR-TKI resistance in EGFR mutant lung cancer in Japanese patients. These observations provide a rationale for targeting HGF in EGFR-TKI resistance in EGFR mutant lung cancer.