Comparing the safety and efficacy of nintedanib starting dose in patients with connective tissue disease-associated interstitial lung diseases.

OBJECTIVE: This study aimed to analyse whether initiating nintedanib treatment at a reduced dose could improve the treatment continuation rate while maintaining efficacy in patients with connective tissue disease (CTD)-associated interstitial lung disease. METHOD: In total, 51 patients (age 61.6 ± 13.2 years; 38 women, 13 men) were retrospectively analysed. The primary endpoint was the cumulative discontinuation rate due to adverse events. Secondary endpoints included changes in drug dosage, efficacy evaluated based on annual changes in forced vital capacity (FVC), and safety assessed based on the frequency of adverse events. RESULTS: Eighteen patients who started treatment at the standard dose of 300 mg (standard dosage group) were compared with 33 patients who started treatment at a reduced dose (reduced dosage group). Systemic sclerosis was the most common CTD (n = 32), followed by idiopathic inflammatory myopathies and, rarely, rheumatoid arthritis. Both groups exhibited comparable cumulative discontinuation rates due to adverse events and similar frequencies of adverse events. No significant differences were observed in maintenance doses between the two groups; however, patients in the reduced dosage group had a lower cumulative dose for up to 52 weeks than those in the standard dosage group. No significant differences were observed in changes in FVC between the two groups. CONCLUSION: There was no evidence for a difference between the two groups in terms of discontinuation rates, efficacy, and safety. To provide further evidence, future studies using more precise dose-escalation protocols are warranted.

Final overall survival results of WJTOG3405, a randomized phase III trial comparing gefitinib versus cisplatin with docetaxel as the first-line treatment for patients with stage IIIB/IV or postoperative recurrent EGFR mutation-positive non-small-cell lung cancer.

BACKGROUND: Primary analysis of the phase III study WJTOG 3405 demonstrated superiority of progression-free survival (PFS) for gefitinib (G) in patients treated with the epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) gefitinib compared with cisplatin plus docetaxel (CD) as the first-line treatment of stage IIIB/IV or postoperative recurrent EGFR mutation-positive non-small-cell lung cancer. This report presents final overall survival (OS) data. PATIENTS AND METHODS: Patients were randomized between G (250 mg/day orally) and cisplatin (80 mg/m2 intravenously) plus docetaxel (60 mg/m2 i.v.), administered every 21 days for three to six cycles. After the exclusion of 5 patients, 172 patients (86 in each group, modified intention-to-treat population) were included in the survival analysis. OS was re-evaluated using updated data (data cutoff, 30 September 2013; median follow-up time 59.1 months). The Kaplan-Meier method and the log-rank test were used for analysis, and hazard ratios (HRs) for death were calculated using the Cox proportional hazards model. RESULTS: OS events in the G group and CD group were 68 (79.1%) out of 86 and 59 (68.6%) out of 86, respectively. Median survival time for G and CD were 34.9 and 37.3 months, respectively, with an HR of 1.252 [95% confidence interval (CI): 0.883-1.775, P = 0.2070]. Multivariate analysis identified postoperative recurrence and stage IIIB/IV disease as independent prognostic factors, with an HR of 0.459 (95% CI: 0.312-0.673, P < 0.001). Median survival time (postoperative recurrence versus stage IIIB/IV disease) were 44.5 and 27.5 months in the G group and 45.5 and 32.8 months in the CD group, respectively. CONCLUSION: G did not show OS benefits over CD as the first-line treatment. OS of patients with postoperative recurrence was better than that of stage IIIB/IV disease, even though both groups had metastatic disease.This study was registered with UMIN (University Hospital Medical Information Network in Japan), number 000000539.

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.

Effect of dose adjustment on the safety and efficacy of afatinib for EGFR mutation-positive lung adenocarcinoma: post hoc analyses of the randomized LUX-Lung 3 and 6 trials.

BACKGROUND: Afatinib 40 mg/day is approved for first-line treatment of EGFR mutation-positive non-small-cell lung cancer (NSCLC). In the case of drug-related grade ≥3 or selected prolonged grade 2 adverse events (AEs), the dose can be reduced by 10 mg decrements to a minimum of 20 mg. Here, we evaluate the influence of afatinib dose reduction on AEs, pharmacokinetics and progression-free survival (PFS) in the phase III LUX-Lung 3 and 6 (LL3/6) trials. PATIENTS AND METHODS: Treatment-naïve patients with advanced EGFR mutation-positive NSCLC in LL3 (global) and LL6 (China, Thailand, South Korea) were randomized to afatinib or chemotherapy. All afatinib-treated patients (LL3, n = 229; LL6, n = 239) were included in the post hoc analyses. Incidence and severity of common AEs before and after afatinib dose reduction were assessed. Afatinib plasma concentrations were compared in patients who reduced to 30 mg versus those remaining at 40 mg. PFS was compared between patients who dose reduced within the first 6 months of treatment and those who did not. RESULTS: Dose reductions occurred in 53.3% (122/229) and 28.0% (67/239) of patients in LL3 and LL6, respectively; most (86.1% and 82.1%) within the first 6 months of treatment. Dose reduction led to decreases in the incidence of drug-related AEs, and was more likely in patients with higher afatinib plasma concentrations. On day 43, patients who dose reduced to 30 mg (n = 59) had geometric mean afatinib plasma concentrations of 23.3 ng/ml, versus 22.8 ng/ml in patients who remained on 40 mg (n = 284). The median PFS was similar in patients who dose reduced during the first 6 months versus those who did not {LL3: 11.3 versus 11.0 months [hazard ratio (HR) 1.25]; LL6: 12.3 versus 11.0 months (HR 1.00)}. CONCLUSIONS: Tolerability-guided dose adjustment is an effective measure to reduce afatinib-related AEs without affecting therapeutic efficacy. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov identifiers: NCT00949650 and NCT0112393.

Characterization of patients at high risk of melanoma in Austria.

BACKGROUND: Risk of melanoma is determined by genetic and exogenous factors. Only a few studies have included both characteristics in a comprehensive multivariable analysis. OBJECTIVES: To find determinants of patients at high risk of melanoma in Austria, including phenotype, genotype and lifestyle characteristics in comprehensive analyses. METHODS: In total, 1668 patients with melanoma from the M3 case-control study were studied. Overall, 567 participants were sequenced for CDKN2A, 232 for CDK4, 123 for MITF encoding the variant E318K and 964 for MC1R. RESULTS: Patients with melanoma with a positive family history (n = 190, 11·6%), multiple primary melanomas (n = 261, 15·7%) and younger age (< 50 years, n = 675, 40·5%) were defined as being at high risk. All other patients with melanoma were defined as the reference group. We found significant differences between those two groups and between the high-risk subgroups (positive family history, multiple primary melanomas and younger age). Pigmentation phenotype was associated with the high-risk group in general (childhood freckling, odds ratio 1·46, P = 0·007; blond/reddish hair colour, odds ratio 1·43, P = 0·011). Patients with a positive family history and patients with early-onset disease were similar regarding both their phenotypic characteristics and external factors. Established high-risk mutations in CDKN2A were found in cases with a positive family history (n = 12) or multiple melanomas (n = 2). Moreover, we found three patients carrying the MITF p.E318K variant, two with a CDK4 variant and seven with nonsynonymous MC1R variants with undescribed biological significance, of which four were predicted as damaging. CONCLUSIONS: Austrian patients could represent a reservoir for novel genetic variants. Further investigation of populations in Central and Eastern Europe might reveal more novel and disease-relevant variants.

Survival, quality-adjusted survival, and other clinical end points in older advanced non-small-cell lung cancer patients treated with albumin-bound paclitaxel.

BACKGROUND: This analysis compared the quality-adjusted survival and clinical outcomes of albumin-bound paclitaxel+carboplatin (nab-PC) vs solvent-based paclitaxel+carboplatin (sb-PC) as first-line therapy in advanced non-small-cell lung cancer (NSCLC) in older patients. METHODS: Using age-based subgroup data from a randomised Phase-3 clinical trial, nab-PC and sb-PC were compared with respect to overall response rate (ORR), overall survival (OS), progression-free survival (PFS), quality of life (QoL), safety/toxicity, and quality-adjusted time without symptoms or toxicity (Q-TWiST) with ages ⩾60 and ⩾70 years as cut points. RESULTS: Among patients aged ⩾60 years (N=546), nab-PC (N=265) significantly increased ORR and prolonged OS, despite a non-significant improvement in PFS, vs sb-PC (N=281). Nab-PC improved QoL and was associated with less neuropathy, arthralgia, and myalgia but resulted in more anaemia and thrombocytopenia. Nab-PC yielded significant Q-TWiST benefits (11.1 vs 9.8 months; 95% CI of gain: 0.2-2.6), with a relative Q-TWiST gain of 10.8% (ranging from 6.4% to 15.1% in threshold analysis). In the ⩾70 years age group, nab-PC showed similar, but non-significant, ORR, PFS, and Q-TWiST benefits and significantly improved OS and QoL. CONCLUSION: Nab-PC as first-line therapy in older patients with advanced NSCLC increased ORR, OS, and QoL and resulted in quality-adjusted survival gains compared with standard sb-PC.

Association of PD-L1 overexpression with activating EGFR mutations in surgically resected nonsmall-cell lung cancer.

BACKGROUND: Recent clinical trials have shown that immune-checkpoint blockade yields a clinical response in a subset of individuals with advanced nonsmall-cell lung cancer (NSCLC). We examined whether the expression of programmed death-ligand 1 (PD-L1) is related to clinicopathologic or prognostic factors in patients with surgically resected NSCLC. PATIENTS AND METHODS: The expression of PD-L1 was evaluated by immunohistochemical analysis in 164 specimens of surgically resected NSCLC. Cell surface expression of PD-L1 in NSCLC cell lines was quantified by flow cytometry. RESULTS: Expression of PD-L1 in tumor specimens was significantly higher for women than for men, for never smokers than for smokers, and for patients with adenocarcinoma than for those with squamous cell carcinoma. Multivariate analysis revealed that the presence of epidermal growth factor receptor gene (EGFR) mutations and adenocarcinoma histology were significantly associated with increased PD-L1 expression in a manner independent of other factors. Cell surface expression of PD-L1 was also significantly higher in NSCLC cell lines positive for activating EGFR mutations than in those with wild-type EGFR. The EGFR inhibitor erlotinib downregulated PD-L1 expression in the former cell lines but not in the latter, suggesting that PD-L1 expression is increased by EGFR signaling conferred by activating EGFR mutations. A high level of PD-L1 expression in resected tumor tissue was associated with a significantly shorter overall survival for NSCLC patients. CONCLUSIONS: High expression of PD-L1 was associated with the presence of EGFR mutations in surgically resected NSCLC and was an independent negative prognostic factor for this disease.

Actinic damage on the back is significantly determined by MC1R variants and previous sun exposure compared with other body sites in a multivariate analysis.

BACKGROUND: Only recently, site-dependent associations of actinic damage with melanoma were identified in our study population. OBJECTIVES: To elucidate the diverse aetiologies for actinic damage at different body sites. METHODS: We performed multivariate logistic regression analyses to identify independent risk factors for actinic damage on the face, hands and the back in 2112 participants of central European origin. RESULTS: For actinic damage on the face, age was the only risk factor that remained consistently significant in a multivariate analysis, whereas actinic damage on the back was predominantly associated with number of sunburns, freckles in childhood, holiday weeks and male sex. Moreover, we identified a particular significance of MC1R variants and dorsal actinic skin damage. CONCLUSIONS: The particular effect of MC1R variants and sun exposure during recreational time on dorsal actinic damage indicates that actinic damage on the back is more informative regarding susceptibility to sunlight and past sun exposure associated with melanoma risk.

Safety and efficacy analysis by histology of weekly nab-paclitaxel in combination with carboplatin as first-line therapy in patients with advanced non-small-cell lung cancer.

BACKGROUND: This analysis compared the efficacy and safety outcomes by histology of nab-paclitaxel (nab-P) plus carboplatin (C) versus solvent-based paclitaxel (sb-P) plus C in patients with advanced non-small-cell lung cancer (NSCLC) based on preplanned stratification factors specified in the phase III trial protocol. PATIENTS AND METHODS: Patients with untreated stage III/IV NSCLC received 100 mg/m(2) nab-P weekly and C (area under the curve, AUC = 6) every 3 weeks (q3w) or 200 mg/m(2) sb-P plus C (AUC = 6) q3w. Primary end point was objective overall response rate (ORR). RESULTS: nab-P/C versus sb-P/C produced a significantly higher ORR (41% versus 24%; response rate ratio [RRR] 1.680; P < 0.001) in patients with squamous cell (SCC) NSCLC. For nab-P/C versus sb-P/C, ORRs were 26% versus 27% (RRR 0.966; P = 0.814) in patients with adenocarcinoma, 33% versus 15% (RRR 2.167; P = 0.323) in patients with large cell carcinoma (LC), and 24% versus 15% (RRR 1.593; P = 0.372) in patients with not otherwise specified histology. Median overall survival for nab-P/C versus sb-P/C in patients with SCC was 10.7 versus 9.5 months (HR 0.890; P = 0.310), and 12.4 versus 10.6 months (HR 1.208; P = 0.721) for patients with LC. nab-P/C produced significantly (P < 0.05) less grade 3/4 neuropathy and arthralgia, whereas sb-P/C produced less thrombocytopenia and anemia. CONCLUSION(S): First-line nab-P/C demonstrated a favorable risk-benefit profile in patients with NSCLC regardless of histology.

Safety and efficacy of weekly nab®-paclitaxel in combination with carboplatin as first-line therapy in elderly patients with advanced non-small-cell lung cancer.

BACKGROUND: This analysis evaluates safety and efficacy in elderly (≥ 70 years old) versus younger patients enrolled in a phase III advanced non-small-cell lung cancer (NSCLC) trial. PATIENTS AND METHODS: Untreated stage IIIB/IV patients with PS 0/1 were randomly assigned (1:1) to carboplatin AUC6, day 1 every 3 weeks, and either nab-paclitaxel (Abraxane) 100 mg/m(2) weekly (nab-P/C) or solvent-based paclitaxel (Taxol) 200 mg/m(2) day 1 every 3 weeks (sb-P/C). The primary end-point was overall response rate (ORR). RESULTS: Fifteen percent of 1052 enrolled patients were elderly: nab-P/C, n = 74; sb-P/C, n = 82. In both age cohorts, the ORR was higher with nab-P/C versus sb-P/C (age ≥ 70: 34% versus 24%, P = 0.196; age <70: 32% versus 25%, P = 0.013). In elderly patients, progression-free survival (PFS) trended in favor of nab-P/C (median 8.0 versus 6.8 months, hazard ratio (HR) 0.687, P = 0.134), and overall survival (OS) was significantly improved (median 19.9 versus 10.4 months, HR 0.583, P = 0.009). In younger patients, PFS (median 6.0 versus 5.8 months, HR 0.903, P = 0.256) and OS (median 11.4 versus 11.3 months, HR 0.999, P = 0.988) were similar in both arms. Adverse events were similar in both age groups, with less neutropenia (P = 0.015), neuropathy (P = 0.001), and arthralgia (P = 0.029), and increased anemia (P = 0.007) with nab-P/C versus sb-P/C. CONCLUSIONS: In elderly NSCLC patients, nab-P/C as first-line therapy was well tolerated and improved the ORR and PFS, with substantially longer OS versus sb-PC.

Efficacy and safety analysis according to histology for S-1 in combination with carboplatin as first-line chemotherapy in patients with advanced non-small-cell lung cancer: updated results of the West Japan Oncology Group LETS study.

BACKGROUND: A phase III study (Lung Cancer Evaluation of TS-1) previously demonstrated noninferiority in terms of overall survival (OS) at interim analysis for carboplatin-S-1 compared with carboplatin-paclitaxel for first-line treatment of advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: A total of 564 patients were randomly assigned to receive either carboplatin on day 1 plus oral S-1 on days 1-14 or carboplatin-paclitaxel on day 1 every 21 days. Updated results and post hoc subgroup analysis according to tumor histology are presented. RESULTS: The updated analysis revealed a median OS of 15.2 months in the carboplatin-S-1 arm and 13.1 months in the carboplatin-paclitaxel arm, with a hazard ratio (HR) of 0.956 [95% confidence interval (CI) 0.793-1.151], consistent with the previous primary analysis. Median OS was 14.0 months in the carboplatin-S-1 arm and 10.6 months in the carboplatin-paclitaxel arm (HR 0.713; 95% CI 0.476-1.068) for patients with squamous cell carcinoma (SCC), with corresponding values of 15.5 and 13.9 months (HR 1.060; 95% CI 0.859-1.308) for those with non-SCC. CONCLUSIONS: These results establish the efficacy and safety of carboplatin-S-1 in patients with advanced NSCLC regardless of tumor histology.

Combined effect of ALK and MEK inhibitors in EML4-ALK-positive non-small-cell lung cancer cells.

BACKGROUND: Although most non-small-cell lung cancer (NSCLC) patients with the echinoderm microtubule-associated protein-like 4 (EML4) - anaplastic lymphoma kinase (ALK) fusion gene - benefit from ALK tyrosine kinase inhibitors (ALK-TKIs), the efficacy of these drugs varies greatly among individuals. METHODS: The antitumour action of ALK-TKIs in EML4-ALK-positive NSCLC cell lines was evaluated from their effects on cell proliferation, signal transduction, and apoptosis. RESULTS: The ALK-TKI TAE684 inhibited cell proliferation and induced apoptosis, in association with inhibition of STAT3 and ERK phosphorylation, in EML4-ALK-positive H3122 cells. TAE684 inhibited STAT3 phosphorylation, but not ERK phosphorylation, and it showed little effect on cell proliferation or apoptosis, in EML4-ALK-positive H2228 cells. The combination of TAE684 and a MEK inhibitor-induced marked apoptosis accompanied by inhibition of STAT3 and ERK pathways in H2228 cells. Such dual interruption of STAT3 and ERK pathways induced downregulation of the antiapoptotic protein survivin and upregulation of the proapoptotic protein BIM. CONCLUSION: Our results indicate that interruption of both STAT3-survivin and ERK-BIM pathways is required for induction of apoptosis in NSCLC harbouring EML4-ALK, providing a rationale for combination therapy with ALK and MEK inhibitors in EML4-ALK-positive NSCLC patients for whom ALK inhibitors alone are ineffective.

Clinical outcome for EML4-ALK-positive patients with advanced non-small-cell lung cancer treated with first-line platinum-based chemotherapy.

BACKGROUND: The EML4-ALK fusion oncogene represents a recently identified molecular target in a subset of patients with non-small-cell lung cancer (NSCLC). Limited data have been available, however, on the outcome of first-line platinum-based chemotherapy in patients with EML4-ALK-positive advanced NSCLC who have not been treated with an ALK kinase inhibitor. PATIENTS AND METHODS: The efficacy of platinum-based chemotherapy was compared between patients with advanced nonsquamous NSCLC who harbor EML4-ALK and those who harbor EGFR mutations and those with neither molecular abnormality. RESULTS: Among 200 patients with advanced nonsquamous NSCLC, 18 (9.0%) were positive for EML4-ALK, 31 (15.5%) harbored EGFR mutations, and 151 (75.5%) were wild type for both abnormalities. Platinum-based combination chemotherapy showed similar efficacies in the EML4-ALK, EGFR mutation, and wild-type cohorts in terms of response rate and progression-free survival, and overall survival in the EML4-ALK cohort closely resembled that in the wild-type cohort. Within the EML4-ALK cohort, patients with variants 1 or 3 of the fusion gene were predominant and did not appear to differ in their sensitivity to the platinum-based regimens. CONCLUSION: Patients with EML4-ALK-positive advanced NSCLC manifest an aggressive clinical course similar to that of those with wild-type tumors if the effective targeted therapy is not instituted.

Postprogression survival for first-line chemotherapy of patients with advanced non-small-cell lung cancer.

BACKGROUND: Given the growing number of drugs available for non-small-cell lung cancer (NSCLC), an effect of first-line chemotherapy on overall survival (OS) might be confounded by subsequent therapies. We examined the relation between postprogression survival (PPS) and OS in phase III trials of first-line chemotherapy for advanced NSCLC. PATIENTS AND METHODS: A literature search identified 69 trials that were published during the past decade. We partitioned OS into progression-free survival (PFS) and PPS and evaluated the relation between OS and either PFS or PPS. We also examined whether any association might be affected by the year of completion of trial enrollment. RESULTS: The average PPS was longer in recent trials than in older trials (6.5 versus 4.4 months, P < 0.0001). For all trials, PPS was strongly associated with OS (r = 0.82), whereas PFS was moderately associated with OS (r = 0.43). The correlation between OS and PPS in recent trials was stronger than that in older trials (r = 0.89 and 0.66). CONCLUSIONS: Our findings indicate that, especially for recent trials, PPS is highly associated with OS in first-line chemotherapy for advanced NSCLC, whereas PFS is only moderately associated with OS.

Assessment of the albumin-bilirubin grade as a prognostic factor in patients with non-small-cell lung cancer receiving anti-PD-1-based therapy.

INTRODUCTION: The albumin-bilirubin (ALBI) grade is a novel indicator of the liver function. Some studies showed that the ALBI grade was a prognostic and predictive biomarker for the efficacy of chemotherapy in cancer patients. The association between the ALBI grade and outcomes in patients with non-small-cell lung cancer (NSCLC) treated with cancer immunotherapy, however, is poorly understood. METHODS: We retrospectively enrolled 452 patients with advanced or recurrent NSCLC who received anti-programmed cell death protein 1 (PD-1)-based therapy between 2016 and 2019 at three medical centers in Japan. The ALBI score was calculated from albumin and bilirubin measured at the time of treatment initiation and was stratified into three categories, ALBI grade 1-3, with reference to previous reports. We examined the clinical impact of the ALBI grade on the outcomes of NSCLC patients receiving anti-PD-1-based therapy using Kaplan-Meier survival curve analysis with log-rank test and Cox proportional hazards regression analysis. RESULTS: The classifications of the 452 patients were as follows: grade 1, n = 158 (35.0%); grade 2, n = 271 (60.0%); and grade 3, n = 23 (5.0%). Kaplan-Meier survival curve analysis showed that the ALBI grade was significantly associated with progression-free survival and overall survival. Moreover, Cox regression analysis revealed that the ALBI grade was an independent prognostic factor for progression-free survival and overall survival. CONCLUSION: The ALBI grade was an independent prognostic factor for survival in patients with advanced or recurrent NSCLC who receive anti-PD-1-based therapy. These findings should be validated in a prospective study with a larger sample size.

Differential roles of trans-phosphorylated EGFR, HER2, HER3, and RET as heterodimerisation partners of MET in lung cancer with MET amplification.

BACKGROUND: MET is a receptor tyrosine kinase (RTK) whose gene is amplified in various tumour types. We investigated the roles and mechanisms of RTK heterodimerisation in lung cancer with MET amplification. METHODS: With the use of an RTK array, we identified phosphorylated RTKs in lung cancer cells with MET amplification. We examined the roles and mechanisms of action of these RTKs with immunoprecipitation, annexin V binding, and cell migration assays. RESULTS: We identified epidermal growth factor receptor (EGFR), human EGFR (HER)2, HER3, and RET in addition to MET as highly phosphorylated RTKs in lung cancer cells with MET amplification. Immunoprecipitation revealed that EGFR, HER2, HER3, and RET each formed a heterodimer exclusively with MET and that these associations were markedly reduced in extent by treatment with a MET kinase inhibitor. RNA interference-mediated depletion of EGFR, HER2, or HER3 induced apoptosis in association with inhibition of AKT and ERK signalling pathways, whereas depletion of HER2 or RET inhibited both cell migration and STAT3 signalling. CONCLUSION: Our data suggest that heterodimers of MET with EGFR, HER2, HER3, or RET have differential roles in tumour development, and they provide new insight into the function of trans-phosphorylated RTKs as heterodimerisation partners of MET in lung cancer with MET amplification.