Daijiro Harada

The Role of STAT3 in Non-Small Cell Lung Cancer.

Persistent phosphorylation of signal transducer and activator of transcription 3 (STAT3) has been demonstrated in 22%~65% of non-small cell lung cancers (NSCLC). STAT3 activation is mediated by receptor tyrosine kinases, such as epidermal growth factor receptor (EGFR) and MET, cytokine receptors, such as IL-6, and non-receptor kinases, such as Src. Overexpression of total or phosphorylated STAT3 in resected NSCLC leads to poor prognosis. In a preclinical study, overexpression of STAT3 was correlated with chemoresistance and radioresistance in NSCLC cells. Here, we review the role of STAT3 and the mechanisms of treatment resistance in malignant diseases, especially NSCLC. As STAT3 is a critical mediator of the oncogenic effects of EGFR mutations, we discuss STAT3 pathways in EGFR-mutated NSCLC, referring to mechanisms of EGFR tyrosine kinase inhibitor resistance.

Phase II Trial of Gefitinib in Combination with Bevacizumab as First-Line Therapy for Advanced Non–Small Cell Lung Cancer with Activating EGFR Gene Mutations: The Okayama Lung Cancer Study Group Trial 1001

Purpose: Whether bevacizumab enhances the effect of the epidermal growth factor receptor (EGFR) inhibitor gefitinib on EGFR mutant non–small cell lung cancers (NSCLCs) remains unknown. We conducted a phase II trial to investigate the efficacy and safety of gefitinib when combined with bevacizumab as first-line therapy in patients with advanced NSCLC harboring EGFR gene mutations. Methods: In this trial, 42 patients with a performance status of 0 to 2 received gefitinib (250 mg/d) and bevacizumab (15 mg/kg, every 3 weeks). The primary end point of this study was the 1-year progression-free survival (PFS) rate. We assumed that a 1-year PFS rate of 55% would indicate potential usefulness and that a 1-year PFS rate of 40% would constitute the lower limit of interest. Results: Forty-two patients were enrolled in the study with a median age of 73 (range 42–86) years. Activating EGFR gene mutations included exon 19 deletion (57%) and L858R point mutations in exon 21 (38%). The objective response rate was 73.8% and included two complete responses. The 1-year PFS rate and median PFS time were 56.7% (95% confidence interval [CI] 39.9–70.5) and 14.4 months (95% CI 10.1–19.2), respectively. The median PFS differed significantly between EGFR exon 19 deletion and the L858R point mutation (18.0 versus 9.4 months, respectively; p = 0.006). The median overall survival had not yet been reached. Severe adverse events included grade 3 skin rash (15%), hypertension (17%), aspartate transaminase/alanine aminotransferase elevation (17%), proteinuria (7%), intracranial hemorrhage (2%), and grade 4 perforation of the digestive tract (2%). There were no treatment-related deaths. Conclusion: Gefitinib in combination with bevacizumab as first-line therapy seems to be a favorable and well-tolerated treatment for patients with advanced NSCLC with activating EGFR gene mutations, especially those with EGFR exon 19 deletion mutations, although the primary end point was not met because the lower limit of the CI was less than 40%.

Subpopulation of small-cell lung cancer cells expressing CD133 and CD87 show resistance to chemotherapy.

Tumors are presumed to contain a small population of cancer stem cells (CSCs) that initiate tumor growth and promote tumor spreading. Multidrug resistance in CSCs is thought to allow the tumor to evade conventional therapy. This study focused on expression of CD133 and CD87 because CD133 is a putative marker of CSCs in some cancers including lung, and CD87 is associated with a stem‐cell‐like property in small‐cell lung cancer (SCLC). Six SCLC cell lines were used. The expression levels of CD133 and CD87 were analyzed by real‐time quantitative reverse transcription‐polymerase chain reaction and flow cytometry. CD133+/− and CD87+/− cells were isolated by flow cytometry. The drug sensitivities were determined using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Non‐obese diabetic/severe combined immunodeficiency mice were used for the tumor formation assay. SBC‐7 cells showed the highest expression levels of both CD133 and CD87 among the cell lines. CD133−/CD87−, CD133+/CD87−, and CD133−/CD87+ cells were isolated from SBC‐7 cells; however, CD133+/CD87+ cells could not be obtained. Both CD133+/CD87− and CD133−/CD87+ subpopulations showed a higher resistance to etoposide and paclitaxel and greater re‐populating ability than the CD133−/CD87− subpopulation. CD133+/CD87− cells contained more G0 quiescent cells than CD133−/CD87− cells. By contrast, CD133−/CD87− cells showed the highest tumorigenic potential. In conclusion, both CD133 and CD87 proved to be inadequate markers for CSCs; however, they might be beneficial for predicting resistance to chemotherapy. (Cancer Sci 2013; 104: 78–84)

JAK2-related pathway induces acquired erlotinib resistance in lung cancer cells harboring an epidermal growth factor receptor-activating mutation

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, such as gefitinib and erlotinib, are effective for non‐small cell lung cancer with activating EGFR mutations. However, even in patients with an initial dramatic response to such a drug, acquired resistance develops after 6–12 months. A secondary mutation of T790M in EGFR and amplification of the MET gene account for this resistance; however, the mechanism(s) of approximately 30% of acquired resistance cases remain unknown. We established an erlotinib‐resistant lung cancer cell line named PC‐9/ER3 that harbors an EGFR mutation after continuously exposing PC‐9 cells to erlotinib. PC‐9/ER3 cells were 136‐fold more resistant to erlotinib than the parental cells. Although the PC‐9/ER3 cells did not carry the T790M mutation or MET amplification and had similar levels of phosphorylated (p) STAT3, pJAK2 increased in the resistant cells. It was found in the present study that 3–12 h of exposure to erlotinib in both cell lines did not affect pJAK2 expression, but did result in increased pSTAT3 expression. pAkt in PC‐9/ER3 cells was less suppressed than in PC‐9 cells, although pEGFR and pMAPK were markedly suppressed in both cell lines. The combined treatment of erlotinib plus a JAK2 inhibitor (JSI‐124) suppressed pAkt in PC‐9/ER3 cells. Similarly, the combination of erlotinib plus JSI‐124 or siRNA against JAK2 restored sensitivity to erlotinib in PC‐9/ER3 cells. The combination of erlotinib plus JSI‐124 was also effective for reducing PC‐9/ER3 tumors in a murine xenograft model. Our results suggest that the activation of JAK2 partially accounts for acquired erlotinib resistance.(Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02363.x, 2012)

Src mediates ERK reactivation in gefitinib resistance in non-small cell lung cancer

To study epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance mechanisms, we established a novel gefitinib-resistant lung cancer cell line derived from an EGFR-mutant non-small cell lung cancer cell line (PC-9) pretreated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (designated PC9-GR). We found that gefitinib substantially suppressed the EGFR signaling pathway, whereas ERK was reactivated after several hours in PC9-GR but not in PC-9. The combination of gefitinib with ERK inhibition (by U0126) restored gefitinib susceptibility in PC9-GR, but PI3K-Akt inhibition with LY294002 did not. Although the levels of phosphorylated Src were up-regulated simultaneously with ERK reactivation, neither ERK suppression using U0126 nor an ERK-specific siRNA induced Src phosphorylation. Furthermore, dual inhibition of EGFR and Src restored gefitinib sensitivity in PC9-GR in vitro and in vivo. In conclusion, our results indicate that Src-mediated ERK reactivation may play a role in a novel gefitinib resistance mechanism, and that the combined use of gefitinib with a Src inhibitor may be a potent strategy to overcome this resistance.

Monitoring of somatic mutations in circulating cell-free DNA by digital PCR and next-generation sequencing during afatinib treatment in patients with lung adenocarcinoma positive for EGFR activating mutations

Background Analysis of circulating cell-free DNA (cfDNA) is under intensive investigation for its potential to identify tumor somatic mutations. We have now explored the usefulness of such liquid biopsy testing with both the digital polymerase chain reaction (dPCR) and next-generation sequencing (NGS) during treatment of patients with the epidermal growth factor receptor (EGFR) inhibitor afatinib. Patients and methods Eligible patients had advanced lung adenocarcinoma with EGFR activating mutations and were treated with afatinib. Plasma samples were collected before and during (4 and 24 weeks) afatinib treatment as well as at disease progression. Tumor and plasma DNA were analyzed by dPCR and NGS. Results Thirty-five patients were enrolled. The objective response rate and median progression-free survival (PFS) were 77.1% and 13.8 months, respectively. Tumor and plasma DNA were available for 32 patients. dPCR and NGS detected EGFR activating mutations in 81.3% and 71.9% of baseline cfDNA samples, respectively. In 19 patients treated with afatinib for ≥24 weeks, the number of EGFR mutant alleles detected in cfDNA by dPCR declined rapidly and markedly after treatment onset, becoming undetectable or detectable at only a low copy number (<10 copies per milliliter) at 4 weeks. Median PFS was slightly longer for patients with undetectable EGFR mutant alleles in cfDNA at 4 weeks than for those in whom such alleles were detectable (14.3 versus 10.0 months). A total of 45 somatic mutations was identified in baseline tumor DNA, and 30 (66.7%) of these mutations were identified in cfDNA by NGS. Allele frequency for somatic mutations in cfDNA determined by NGS changed concordantly during afatinib treatment with the number of EGFR mutant alleles determined by dPCR. Conclusions Monitoring of cfDNA by dPCR is informative for prediction of afatinib efficacy, whereas that by NGS is reliable and has the potential to identify mechanisms of treatment resistance.

A Phase II Study of Trastuzumab Emtansine in HER2-Positive Non–Small Cell Lung Cancer

&NA; Trastuzumab emtansine (T‐DM1), an anti–erb‐b2 receptor tyrosine kinase 2 (HER2) antibody‐drug conjugate, has been shown to significantly improve survival in HER2‐positive breast cancer. We report a phase II trial of T‐DM1 monotherapy in relapsed NSCLC with documented HER2 positivity (an immunohistochemistry [IHC] score of 3+, both an IHC score of 2+ and fluorescence in situ hybridization positivity, or exon 20 mutation). This study was terminated early because of limited efficacy. The demographic characteristics in the 15 assessable patients were as follows: median age, 67 years; male sex, 47%; performance status of 0 to 1, 80%; HER2 status IHC 3+, 33%; HER status IHC 2+/fluorescence in situ hybridization–positive, 20%; and exon 20 mutation, 47%. The median number of delivered cycles was 3 (range 1–11). One patient achieved a partial response with an objective response rate of 6.7% (90% confidence interval: 0.2–32.0). With a median follow‐up time of 9.2 months, the median progression‐free survival time and median survival time were 2.0 and 10.9 months, respectively. Grade 3 or 4 adverse events included thrombocytopenia (40%) and hepatotoxicity (20%) without any treatment‐related deaths. T‐DM1 had a limited efficacy for HER2‐positive NSCLC in our cohort. Applying the concept of precision medicine to tumors appears challenging; thus, additional molecular approaches are warranted.

Protocol Design for the Bench to Bed Trial in Alectinib-Refractory Non–Small-Cell Lung Cancer Patients Harboring the EML4-ALK Fusion Gene (ALRIGHT/OLCSG1405)

Based on our preclinical study results, which showed that the activation of the hepatocyte growth factor/MET pathway is a potential mechanism of acquired resistance to alectinib, we launched the ALRIGHT (OLCSG1405 [alectinib-refractory non-small-cell lung cancer patients harboring the EML4-ALK fusion gene]), a phase II trial of the anaplastic lymphoma kinase (ALK)/MET inhibitor crizotinib in patients with non-small-cell lung cancer refractory to alectinib and harboring the echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion gene. Patients with ALK-rearranged tumors who have developed disease progression during alectinib treatment will receive crizotinib monotherapy until disease progression or the occurrence of unacceptable toxicity. The primary endpoint is set as the objective response rate, assuming that a response in 50% of eligible patients will indicate potential usefulness and that 15% would be the lower limit of interest (1-sided α of 0.05, β of 0.20). The estimated accrual number of patients is 9. The secondary endpoints include progression-free survival, overall survival, adverse events, and patient-reported outcomes. We will also take tissue samples before crizotinib monotherapy to conduct an exploratory analysis of ALK and hepatocyte growth factor/MET expression levels and gene alterations (eg, mutations, amplifications, and translocations). We will obtain information regarding whether crizotinib, which targets not only ALK, but also MET, can truly produce efficacy with acceptable safety profiles in ALK+ non-small-cell lung cancer even in the alectinib-refractory setting.

Obstructive jaundice at the initial presentation in small-cell lung cancer.

Obstructive jaundice sometimes may develop in association with advanced small-cell lung cancer (SCLC); however, SCLC initially presenting with obstructive jaundice is rare. This report presents the cases of two SCLC patients with obstructive jaundice at the initial diagnosis. A 64-year-old male presented with obstructive jaundice due to a tumor at the head of the pancreas. He was diagnosed with SCLC by transbronchial biopsy from a lung tumor in the left upper lobe. Another 74-year-old male was admitted with jaundice due to a tumor in the porta hepatis. He was also diagnosed with SCLC by a fine-needle aspiration biopsy of a lung tumor in the left lower lobe. Both cases were successfully treated with systemic chemotherapy after endoscopic retrograde biliary drainage.

A phase I trial of afatinib and bevacizumab in chemo-naïve patients with advanced non-small-cell lung cancer harboring EGFR mutations: Okayama Lung Cancer Study Group Trial 1404

OBJECTIVE In advanced epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC), treatment with afatinib, a second-generation EGFR-tyrosine kinase inhibitor (TKI), confers a significant survival benefit over platinum-based chemotherapy. The first-generation EGFR-TKIs gefitinib and erlotinib in combination with bevacizumab have improved progression-free survival. We hypothesized that the combination of afatinib with bevacizumab would further improve efficacy, and conducted a phase I trial to test this hypothesis. MATERIALS AND METHODS Untreated patients with advanced EGFR-mutant NSCLC were enrolled. The primary endpoint was safety. Two doses of afatinib, 40mg/day (level 0) and 30mg/day (level -1), were evaluated in combination with 15mg/kg bevacizumab every 3 weeks. Optimal dosing was determined by dose-limiting toxicity (DLT), with the concentration at which ≤4 of 12 patients experienced toxicity considered the recommended dose. RESULTS Nineteen patients were enrolled (level 0:5, level -1:14). Three of the five patients at level 0 experienced a DLT, which indicated that this dose was unfeasible. Three patients at level -1 developed a DLT of grade 3 non-hematological toxicity, which was soon resolved. Grade 3 or worse adverse events were experienced by all five patients at dose level 0 (diarrhea in 2, skin rash in 1, hypoxia in 1, and paronychia in 1), and by three patients at level -1 (diarrhea in 2 and anorexia in 1). Among 16 evaluable patients, 1 had a complete response, 12 had partial responses, and 0 had progressive disease. CONCLUSION Afatinib plus bevacizumab (level -1) was well tolerated and showed evidence of favorable disease control. This combination therapy may represent a potent therapeutic option for patients with EGFR-mutant NSCLC.