Paul K. Paik

Clinical Characteristics of Patients With Lung Adenocarcinomas Harboring BRAF Mutations

PURPOSE BRAF mutations occur in non-small-cell lung cancer. Therapies targeting BRAF mutant tumors have recently been identified. We undertook this study to determine the clinical characteristics of patients with lung adenocarcinomas harboring BRAF mutations. PATIENTS AND METHODS We reviewed data from consecutive patients with lung adenocarcinoma whose tumors underwent BRAF, EGFR, and KRAS mutation testing as well as fluorescence in situ hybridization for ALK rearrangements. Patient characteristics including age, sex, race, performance status, smoking history, stage, treatment history, and overall survival were collected. RESULTS Among 697 patients with lung adenocarcinoma, BRAF mutations were present in 18 patients (3%; 95% CI, 2% to 4%). The BRAF mutations identified were V600E (50%), G469A (39%), and D594G (11%). Mutations in EGFR were present in 24%, KRAS in 25%, and ALK translocations in 6%. In contrast to patients with EGFR mutations and ALK rearrangements who were mostly never smokers, all patients with BRAF mutations were current or former smokers (P < .001). The median overall survival of advanced-stage patients with BRAF mutations was not reached. In comparison, the median overall survival of patients with EGFR mutations was 37 months (P = .73), with KRAS mutations was 18 months (P = .12), and with ALK rearrangements was not reached (P = .64). CONCLUSION BRAF mutations occur in 3% of patients with lung adenocarcinoma and occur more commonly in current and former smokers. The incidence of BRAF mutations other than V600E is significantly higher in lung cancer than in melanoma.

Clarifying the Spectrum of Driver Oncogene Mutations in Biomarker-Verified Squamous Carcinoma of Lung: Lack of EGFR/KRAS and Presence of PIK3CA/AKT1 Mutations

Purpose: There is persistent controversy as to whether EGFR and KRAS mutations occur in pulmonary squamous cell carcinoma (SQCC). We hypothesized that the reported variability may reflect difficulties in the pathologic distinction of true SQCC from adenosquamous carcinoma (AD-SQC) and poorly differentiated adenocarcinoma due to incomplete sampling or morphologic overlap. The recent development of a robust immunohistochemical approach for distinguishing squamous versus glandular differentiation provides an opportunity to reassess EGFR/KRAS and other targetable kinase mutation frequencies in a pathologically homogeneous series of SQCC. Experimental Design: Ninety-five resected SQCCs, verified by immunohistochemistry as ΔNp63+/TTF-1−, were tested for activating mutations in EGFR, KRAS, BRAF, PIK3CA, NRAS, AKT1, ERBB2/HER2, and MAP2K1/MEK1. In addition, all tissue samples from rare patients with the diagnosis of EGFR/KRAS-mutant “SQCC” encountered during 5 years of routine clinical genotyping were reassessed pathologically. Results: The screen of 95 biomarker-verified SQCCs revealed no EGFR/KRAS [0%; 95% confidence interval (CI), 0%–3.8%], four PIK3CA (4%; 95% CI, 1%–10%), and one AKT1 (1%; 95% CI, 0%–5.7%) mutations. Detailed morphologic and immunohistochemical reevaluation of EGFR/KRAS-mutant “SQCC” identified during clinical genotyping (n = 16) resulted in reclassification of 10 (63%) cases as AD-SQC and five (31%) cases as poorly differentiated adenocarcinoma morphologically mimicking SQCC (i.e., adenocarcinoma with “squamoid” morphology). One (6%) case had no follow-up. Conclusions: Our findings suggest that EGFR/KRAS mutations do not occur in pure pulmonary SQCC, and occasional detection of these mutations in samples diagnosed as “SQCC” is due to challenges with the diagnosis of AD-SQC and adenocarcinoma, which can be largely resolved by comprehensive pathologic assessment incorporating immunohistochemical biomarkers. Clin Cancer Res; 18(4); 1167–76. ©2012 AACR.

Response to MET Inhibitors in Patients with Stage IV Lung Adenocarcinomas Harboring MET Mutations Causing Exon 14 Skipping

UNLABELLED Mutations in the MET exon 14 RNA splice acceptor and donor sites, which lead to exon skipping, deletion of the juxtamembrane domain containing the CBL E3-ubiquitin ligase-binding site, and decreased turnover of the resultant aberrant MET protein, were previously reported to be oncogenic in preclinical models. We now report responses to the MET inhibitors crizotinib and cabozantinib in four patients with stage IV lung adenocarcinomas harboring mutations leading to MET exon 14 skipping, highlighting a new therapeutic strategy for the 4% of lung adenocarcinoma patients whose tumors harbor this previously underappreciated genetic alteration. SIGNIFICANCE Oncogenic mutations in the MET exon 14 splice sites that cause exon 14 skipping occur in 4% of lung adenocarcinomas. We report responses to the MET inhibitors crizotinib and cabozantinib in patients with lung adenocarcinomas harboring MET exon 14 splice site mutations, identifying a new potential therapeutic target in this disease.

Prevalence, clinicopathologic associations and molecular spectrum of ERBB2 (HER2) tyrosine kinase mutations in lung adenocarcinomas

Purpose: Activating mutations in the tyrosine kinase domain of HER2 (ERBB2) have been described in a subset of lung adenocarcinomas (ADCs) and are mutually exclusive with EGFR and KRAS mutations. The prevalence, clinicopathologic characteristics, prognostic implications, and molecular heterogeneity of HER2-mutated lung ADCs are not well established in U.S. patients. Experimental Design: Lung ADC samples (N = 1,478) were first screened for mutations in EGFR (exons 19 and 21) and KRAS (exon 2), and negative cases were then assessed for HER2 mutations (exons 19–20) using a sizing assay and mass spectrometry. Testing for additional recurrent point mutations in EGFR, KRAS, BRAF, NRAS, PIK3CA, MEK1, and AKT was conducted by mass spectrometry. ALK rearrangements and HER2 amplification were assessed by FISH. Results: We identified 25 cases with HER2 mutations, representing 6% of EGFR/KRAS/ALK-negative specimens. Small insertions in exon 20 accounted for 96% (24/25) of the cases. Compared with insertions in EGFR exon 20, there was less variability, with 83% (20/24) being a 12 bp insertion causing duplication of amino acids YVMA at codon 775. Morphologically, 92% (23/25) were moderately or poorly differentiated ADC. HER2 mutation was not associated with concurrent HER2 amplification in 11 cases tested for both. HER2 mutations were more frequent among never-smokers (P < 0.0001) but there were no associations with sex, race, or stage. Conclusions: HER2 mutations identify a distinct subset of lung ADCs. Given the high prevalence of lung cancer worldwide and the availability of standard and investigational therapies targeting HER2, routine clinical genotyping of lung ADC should include HER2. Clin Cancer Res; 18(18); 4910–8. ©2012 AACR.

Molecular epidemiology of EGFR and KRAS mutations in 3,026 lung adenocarcinomas: higher susceptibility of women to smoking-related KRAS-mutant cancers.

Purpose: The molecular epidemiology of most EGFR and KRAS mutations in lung cancer remains unclear. Experimental Design: We genotyped 3,026 lung adenocarcinomas for the major EGFR (exon 19 deletions and L858R) and KRAS (G12, G13) mutations and examined correlations with demographic, clinical, and smoking history data. Results: EGFR mutations were found in 43% of never smokers and in 11% of smokers. KRAS mutations occurred in 34% of smokers and in 6% of never smokers. In patients with smoking histories up to 10 pack-years, EGFR predominated over KRAS. Among former smokers with lung cancer, multivariate analysis showed that, independent of pack-years, increasing smoking-free years raise the likelihood of EGFR mutation. Never smokers were more likely than smokers to have KRAS G > A transition mutation (mostly G12D; 58% vs. 20%, P = 0.0001). KRAS G12C, the most common G > T transversion mutation in smokers, was more frequent in women (P = 0.007) and these women were younger than men with the same mutation (median 65 vs. 69, P = 0.0008) and had smoked less. Conclusions: The distinct types of KRAS mutations in smokers versus never smokers suggest that most KRAS-mutant lung cancers in never smokers are not due to second-hand smoke exposure. The higher frequency of KRAS G12C in women, their younger age, and lesser smoking history together support a heightened susceptibility to tobacco carcinogens. Clin Cancer Res; 18(22); 6169–77. ©2012 AACR.

Local Therapy with Continued EGFR Tyrosine Kinase Inhibitor Therapy as a Treatment Strategy in EGFR-Mutant Advanced Lung Cancers That Have Developed Acquired Resistance to EGFR Tyrosine Kinase Inhibitors

Background: Development of acquired resistance limits the utility of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) for the treatment of EGFR-mutant lung cancers. There are no accepted targeted therapies for use after acquired resistance develops. Metastasectomy is used in other cancers to manage oligometastatic disease. We hypothesized that local therapy is associated with improved outcomes in patients with EGFR-mutant lung cancers with acquired resistance to EGFR TKI. Methods: Patients who received non–central nervous system local therapy were identified by a review of data from a prospective biopsy protocol for patients with EGFR-mutant lung cancers with acquired resistance to EGFR TKI therapy and other institutional biospecimen registry protocols. Results: Eighteen patients were identified, who received elective local therapy (surgical resection, radiofrequency ablation, or radiation). Local therapy was well tolerated, with 85% of patients restarting TKI therapy within 1 month of local therapy. The median time to progression after local therapy was 10 months (95% confidence interval [CI]: 2–27 months). The median time until a subsequent change in systemic therapy was 22 months (95% CI: 6–30 months). The median overall survival from local therapy was 41 months (95% CI: 26–not reached). Conclusions: EGFR-mutant lung cancers with acquired resistance to EGFR TKI therapy are amenable to local therapy to treat oligometastatic disease when used in conjunction with continued EGFR inhibition. Local therapy followed by continued treatment with an EGFR TKI is well tolerated and associated with long PFS and OS. Further study in selected individuals in the context of other systemic options is required.

Coexistence of PIK3CA and Other Oncogene Mutations in Lung Adenocarcinoma–Rationale for Comprehensive Mutation Profiling

Phosphoinositide-3-kinase catalytic alpha polypeptide (PIK3CA) encodes the p110α subunit of the mitogenic signaling protein phosphoinositide 3-kinase (PI3K). PIK3CA mutations in the helical binding domain and the catalytic subunit of the protein have been associated with tumorigenesis and treatment resistance in various malignancies. Characteristics of patients with PIK3CA-mutant lung adenocarcinomas have not been reported. We examined epidermal growth factor receptor (EGFR), Kirsten rate sarcoma viral oncogene homolog (KRAS), v-Raf murine sarcoma viral oncogene homolog B1 (BRAF), human epidermal growth factor receptor 2 (HER2), PIK3CA, v-akt murine thymoma vial oncogene homolog 1 (AKT1), v-ras neuroblastoma viral oncogene homolog (NRAS), dual specificity mitogen-activated protein kinase kinase 1 (MEK1), and anaplastic lymphoma kinase (ALK) in patients with adenocarcinoma of the lung to identify driver mutations. Clinical data were obtained from the medical records of individuals with mutations in PIK3CA. Twenty-three of 1,125 (2%, 95% CI: 1–3) patients had a mutation in PIK3CA, 12 in exon 9 (10 E545K and 2 E542K), and 11 in exon 20 (3 H1047L and 8 H1047R). The patients (57% women) had a median age of 66 at diagnosis (range: 34–78). Eight patients (35%) were never smokers. Sixteen of 23 (70%, 95% CI: 49–86) had coexisting mutations in other oncogenes—10 KRAS, 1 MEK1, 1 BRAF, 1 ALK rearrangement, and 3 EGFR exon 19 deletions. We conclude that PIK3CA mutations occur in lung adenocarcinomas, usually concurrently with EGFR, KRAS, and ALK. The impact of PIK3CA mutations on the efficacy of targeted therapies such as erlotinib and crizotinib is unknown. Given the high frequency of overlapping mutations, comprehensive genotyping should be carried out on tumor specimens from patients enrolling in clinical trials of PI3K and other targeted therapies. Mol Cancer Ther; 11(2); 485–91. ©2011 AACR.

Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer

Crizotinib, a selective tyrosine kinase inhibitor (TKI), shows marked activity in patients whose lung cancers harbor fusions in the gene encoding anaplastic lymphoma receptor tyrosine kinase (ALK), but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the clinical observation of a patient with ALK fusion–positive lung cancer who had an exceptional response to an insulin-like growth factor 1 receptor (IGF-1R)-specific antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor insulin receptor substrate 1 (IRS-1), and IRS-1 knockdown enhances the antitumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK and IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, the levels of IGF-1R and IRS-1 are increased in biopsy samples from patients progressing on crizotinib monotherapy. Collectively these data support a role for the IGF-1R–IRS-1 pathway in both ALK TKI–sensitive and ALK TKI–resistant states and provide a biological rationale for further clinical development of dual ALK and IGF-1R inhibitors.

Squamous-cell carcinomas of the lung: emerging biology, controversies, and the promise of targeted therapy

Squamous-cell carcinomas of the lung (SQCLCs) are defined by unique clinicopathological and molecular characteristics that have evolved substantially over time. Historically, these neoplasms were the most common subtype of non-small-cell lung cancers and were regarded as central tumours with high molecular complexity without targetable genetic abnormalities. Today, the incidence of SQCLCs is surpassed by adenocarcinomas of the lung with a shift towards peripheral squamous tumours. Differential responses to cytotoxic and biological treatments have reshaped our approach to standard therapies. Additionally, evidence of unique biology has emerged with the discovery of SOX2 amplification, NFE2L2 and KEAP1 mutations, PI3K pathway changes, FGFR1 amplification, and DDR2 mutations. These discoveries have ushered in a new era of targeted therapeutic agents for patients with this disease. This Review draws attention to the distinct clinical and pathological characteristics of SQCLCs, summarises present experience with existing cytotoxic and targeted therapies, and discusses emerging treatments based on new insights into the biology of this disease.

Association of KRAS and EGFR mutations with survival in patients with advanced lung adenocarcinomas

Lung adenocarcinomas can be distinguished by identifying mutated driver oncogenes, including epidermal growth factor receptor (EGFR) and KRAS. Mutations in EGFR are associated with both improved survival as well as response to treatment with erlotinib and gefitinib. However, the prognostic significance of KRAS has not been evaluated in large numbers of patients and remains controversial. For the current report, the authors examined the association of EGFR and KRAS mutations with survival among patients with advanced lung adenocarcinomas.