Yelena Y. Janjigian

HER2 Amplification: A Potential Mechanism of Acquired Resistance to EGFR Inhibition in EGFR-Mutant Lung Cancers That Lack the Second-Site EGFRT790M Mutation

EGF receptor (EGFR)-mutant lung cancers eventually become resistant to treatment with EGFR tyrosine kinase inhibitors (TKI). The combination of EGFR-TKI afatinib and anti-EGFR antibody cetuximab can overcome acquired resistance in mouse models and human patients. Because afatinib is also a potent HER2 inhibitor, we investigated the role of HER2 in EGFR-mutant tumor cells. We show in vitro and in vivo that afatinib plus cetuximab significantly inhibits HER2 phosphorylation. HER2 overexpression or knockdown confers resistance or sensitivity, respectively, in all studied cell line models. FISH analysis revealed that HER2 was amplified in 12% of tumors with acquired resistance versus only 1% of untreated lung adenocarcinomas. Notably, HER2 amplification and EGFR(T790M) were mutually exclusive. Collectively, these results reveal a previously unrecognized mechanism of resistance to EGFR-TKIs and provide a rationale to assess the status and possibly target HER2 in EGFR-mutant tumors with acquired resistance to EGFR-TKIs.

Dual Inhibition of EGFR with Afatinib and Cetuximab in Kinase Inhibitor-Resistant EGFR-Mutant Lung Cancer with and without T790M Mutations

UNLABELLED EGFR-mutant lung cancers responsive to reversible EGFR inhibitors (gefitinib/erlotinib) develop acquired resistance, mediated by second-site EGFR T790M mutation in >50% of cases. Preclinically, afatinib (irreversible ErbB family blocker) plus cetuximab (anti-EGFR monoclonal antibody) overcomes T790M-mediated resistance. This phase Ib study combining afatinib and cetuximab enrolled heavily pretreated patients with advanced EGFR-mutant lung cancer and acquired resistance to erlotinib/gefitinib. Patients provided post-acquired-resistance tumor samples for profiling EGFR mutations. Among 126 patients, objective response rate (overall 29%) was comparable in T790M-positive and T790M-negative tumors (32% vs. 25%; P = 0.341). Median progression-free survival was 4.7 months (95% confidence interval, 4.3-6.4), and the median duration of confirmed objective response was 5.7 months (range, 1.8-24.4). Therapy-related grade 3/4 adverse events occurred in 44%/2% of patients. Afatinib-cetuximab demonstrated robust clinical activity and a manageable safety profile in EGFR-mutant lung cancers with acquired resistance to gefitinib or erlotinib, both with and without T790M mutations, warranting further investigation. SIGNIFICANCE This article reports the results of a trial combining afatinib and cetuximab in patients with acquired resistance and details the first clinical proof-of-concept for the preclinical hypothesis that a significant proportion of tumors in patients with acquired resistance to gefitinib/erlotinib remain dependent on EGFR signaling for survival.

Mutational landscape of metastatic cancer revealed from prospective clinical sequencing of 10,000 patients

Tumor molecular profiling is a fundamental component of precision oncology, enabling the identification of genomic alterations in genes and pathways that can be targeted therapeutically. The existence of recurrent targetable alterations across distinct histologically defined tumor types, coupled with an expanding portfolio of molecularly targeted therapies, demands flexible and comprehensive approaches to profile clinically relevant genes across the full spectrum of cancers. We established a large-scale, prospective clinical sequencing initiative using a comprehensive assay, MSK-IMPACT, through which we have compiled tumor and matched normal sequence data from a unique cohort of more than 10,000 patients with advanced cancer and available pathological and clinical annotations. Using these data, we identified clinically relevant somatic mutations, novel noncoding alterations, and mutational signatures that were shared by common and rare tumor types. Patients were enrolled on genomically matched clinical trials at a rate of 11%. To enable discovery of novel biomarkers and deeper investigation into rare alterations and tumor types, all results are publicly accessible.

Molecular Classification of Gastric Cancer: A New Paradigm

Purpose: Gastric cancer may be subdivided into 3 distinct subtypes—proximal, diffuse, and distal gastric cancer—based on histopathologic and anatomic criteria. Each subtype is associated with unique epidemiology. Our aim is to test the hypothesis that these distinct gastric cancer subtypes may also be distinguished by gene expression analysis. Experimental Design: Patients with localized gastric adenocarcinoma being screened for a phase II preoperative clinical trial (National Cancer Institute, NCI #5917) underwent endoscopic biopsy for fresh tumor procurement. Four to 6 targeted biopsies of the primary tumor were obtained. Macrodissection was carried out to ensure more than 80% carcinoma in the sample. HG-U133A GeneChip (Affymetrix) was used for cDNA expression analysis, and all arrays were processed and analyzed using the Bioconductor R-package. Results: Between November 2003 and January 2006, 57 patients were screened to identify 36 patients with localized gastric cancer who had adequate RNA for expression analysis. Using supervised analysis, we built a classifier to distinguish the 3 gastric cancer subtypes, successfully classifying each into tightly grouped clusters. Leave-one-out cross-validation error was 0.14, suggesting that more than 85% of samples were classified correctly. Gene set analysis with the false discovery rate set at 0.25 identified several pathways that were differentially regulated when comparing each gastric cancer subtype to adjacent normal stomach. Conclusions: Subtypes of gastric cancer that have epidemiologic and histologic distinctions are also distinguished by gene expression data. These preliminary data suggest a new classification of gastric cancer with implications for improving our understanding of disease biology and identification of unique molecular drivers for each gastric cancer subtype. Clin Cancer Res; 17(9); 2693–701. ©2011 AACR.

An Emerging Entity: Pancreatic Adenocarcinoma Associated with a Known BRCA Mutation: Clinical Descriptors, Treatment Implications, and Future Directions

BACKGROUND BRCA1 and BRCA2 germline mutations are associated with an elevated risk for pancreas adenocarcinoma (PAC). Other BRCA-associated cancers have been shown to have greater sensitivity to platinum and poly(ADP-ribose) polymerase (PARP) inhibitors with better clinical outcomes than in sporadic cases; however, outcomes in BRCA-associated PAC have not been reported. METHODS Patients with a known BRCA1 or BRCA2 mutation and a diagnosis of PAC were identified from the Gastrointestinal Oncology Service, Familial Pancreas Cancer Registry, and Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center. RESULTS Fifteen patients, five male, with a BRCA1 (n = 4) or BRCA2 (n = 11) mutation and PAC and one patient with a BRCA1 mutation and acinar cell carcinoma of the pancreas were identified. Seven female patients (70%) had a prior history of breast cancer. Four patients received a PARP inhibitor alone or in combination with chemotherapy; three demonstrated an initial radiographic partial response by Response Evaluation Criteria in Solid Tumors whereas one patient had stable disease for 6 months. Six patients received platinum-based chemotherapy first line for metastatic disease; five of those patients had a radiographic partial response. CONCLUSION BRCA mutation-associated PAC represents an underidentified, but clinically important, subgroup of patients. This is of particular relevance given the ongoing development of therapeutic agents targeting DNA repair, which may potentially offer a significant benefit to a genetically selected population. We anticipate that further study and understanding of the clinical and biologic features of BRCA-mutant PAC will aid in the identification of tissue biomarkers indicating defective tumor DNA repair pathways in sporadic PAC.

Phase I/II trial of cetuximab and erlotinib in patients with lung adenocarcinoma and acquired resistance to erlotinib

Purpose: In patients with epidermal growth factor receptor (EGFR) mutant lung adenocarcinoma, treatment with erlotinib or gefitinib is associated with a 75% radiographic response rate and progression-free survival of approximately 12 months. The most common mechanism of acquired resistance to erlotinib is development of a secondary mutation in EGFR, suggesting that these tumors continue to depend on EGFR signaling. We hypothesized that combined EGFR blockade would overcome acquired resistance to erlotinib in patients with lung adenocarcinoma. To evaluate the toxicity and efficacy of cetuximab and erlotinib in patients with acquired resistance to erlotinib, we conducted this phase I/II clinical trial. Experimental Design: Patients with lung adenocarcinoma and clinically defined acquired resistance to erlotinib were treated with erlotinib 100 mg daily, along with cetuximab every 2 weeks in three escalating dose cohorts (250 mg/m2, 375 mg/m2, and 500 mg/m2). The recommended phase II dose was then evaluated in a two-stage trial, with a primary end point of objective response rate. Results: A total of 19 patients were enrolled. The most common toxicities for the combination of cetuximab and erlotinib were rash, fatigue, and hypomagnesemia. The recommended phase II dose identified was cetuximab 500 mg/m2 every 2 weeks and erlotinib 100 mg daily. At this dose and schedule, no radiographic responses were seen (0 of 13, 0%, 95% CI, 0–25). Conclusions: Combined EGFR inhibition, with cetuximab 500 mg/m2 every 2 weeks and erlotinib 100 mg daily, had no significant activity in patients with acquired resistance to erlotinib. Clin Cancer Res; 17(8); 2521–7. ©2011 AACR.

Distinct Clinical Course of EGFR-Mutant Resected Lung Cancers: Results of Testing of 1118 Surgical Specimens and Effects of Adjuvant Gefitinib and Erlotinib

Background: EGFR and KRAS mutations are mutually exclusive and predict outcomes with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment in patients with stage IV lung cancers. The clinical significance of these mutations in patients with resected stage I–III lung cancers is unclear. Methods: At our institution, resection specimens from patients with stage I–III lung adenocarcinomas are tested for the presence of EGFR or KRAS mutations during routine pathology analysis such that the results are available before consideration of adjuvant therapy. In a cohort of 1118 patients tested over 8 years, overall survival was analyzed using multivariate analysis to control for potential confounders, including age, sex, stage, and smoking history. The impact of adjuvant erlotinib or gefitinib was examined in an independent data set of patients exclusively with EGFR mutation, in which date of recurrence was recorded. Results: In the overall population, we identified 227 KRAS (25%) and 222 EGFR (20%) mutations. Patients with EGFR-mutant lung cancers had a lower risk of death compared with those without EGFR mutations, overall survival (OS) HR 0.51 (95% confidence interval [CI]: 0.34–0.76, p < 0.001). Patients with KRAS-mutant lung cancers had similar outcomes compared with individuals with KRAS wild-type tumors, OS HR 1.17 (95% CI: 0.87–1.57, p = 0.30). A separate data set includes only patients with EGFR-mutant lung cancers identified over 10 years (n = 286). In patients with resected lung cancers and EGFR mutation, treatment with adjuvant erlotinib or gefitinib was associated with a lower risk of recurrence or death, disease-free survival HR 0.43 (95% CI: 0.26–0.72, p = 0.001), and a trend toward improved OS. Conclusions: Patients with resected stage I–III lung cancers and EGFR mutation have a lower risk of death compared with patients without EGFR mutation. This may be because of treatment with EGFR TKIs. Patients with, and without KRAS mutation have similar OS. These data support reflex testing of resected lung adenocarcinomas for EGFR mutation to provide prognostic information and identify patients for enrollment on prospective clinical trials of adjuvant EGFR TKIs.

MET Expression and Amplification in Patients with Localized Gastric Cancer

Background: MET, the receptor for hepatocyte growth factor, has been proposed as a therapeutic target in gastric cancer. This study assessed the incidence of MET expression and gene amplification in tumors of Western patients with gastric cancer. Methods: Tumor specimens from patients enrolled on a preoperative chemotherapy study (NCI 5700) were examined for the presence of MET gene amplification by FISH, MET mRNA expression by quantitative PCR, MET overexpression by immunohistochemistry (IHC), and for evidence of MET pathway activation by phospho-MET (p-MET) IHC. Results: Although high levels of MET protein and mRNA were commonly encountered (in 63% and 50% of resected tumor specimens, respectively), none of these tumors had MET gene amplification by FISH, and only 6.6% had evidence of MET tyrosine kinase activity by p-MET IHC. Conclusions: In this cohort of patients with localized gastric cancer, the presence of high MET protein and RNA expression does not correlate with MET gene amplification or pathway activation, as evidenced by the absence of amplification by FISH and negative p-MET IHC analysis. Impact: This article shows a lack of MET amplification and pathway activation in a cohort of 38 patients with localized gastric cancer, suggesting that MET-driven gastric cancers are relatively rare in Western patients. Cancer Epidemiol Biomarkers Prev; 20(5); 1021–7. ©2011 AACR.

Impact on disease-free survival of adjuvant erlotinib or gefitinib in patients with resected lung adenocarcinomas that harbor EGFR mutations.

Background: Patients with stage IV lung adenocarcinoma and epidermal growth factor receptor (EGFR) mutation derive clinical benefit from treatment with EGFR tyrosine kinase inhibitors (TKIs). Whether treatment with TKI improves outcomes in patients with resected lung adenocarcinoma and EGFR mutation is unknown. Methods: Data were analyzed from a surgical database of patients with resected lung adenocarcinoma harboring EGFR exon 19 or 21 mutations. In a multivariate analysis, we evaluated the impact of treatment with adjuvant TKI. Results: The cohort consists of 167 patients with completely resected stages I to III lung adenocarcinoma. Ninety-three patients (56%) had exon 19 del, 74 patients (44%) had exon 21 mutations, and 56 patients (33%) received perioperative TKI. In a multivariate analysis controlling for sex, stage, type of surgery, and adjuvant platinum chemotherapy, the 2-year disease-free survival (DFS) was 89% for patients treated with adjuvant TKI compared with 72% in control group (hazard ratio = 0.53; 95% confidence interval: 0.28–1.03; p = 0.06). The 2-year overall survival was 96% with adjuvant EGFR TKI and 90% in the group that did not receive TKI (hazard ratio: 0.62; 95% confidence interval: 0.26–1.51; p = 0.296). Conclusions: Compared with patients who did not receive adjuvant TKI, we observed a trend toward improvement in DFS among individuals with resected stages I to III lung adenocarcinomas harboring mutations in EGFR exon 19 or 21 who received these agents as adjuvant therapy. Based on these data, 320 patients are needed for a randomized trial to prospectively validate this DFS benefit.

Pack‐years of cigarette smoking as a prognostic factor in patients with stage IIIB/IV nonsmall cell lung cancer

This study was undertaken to characterize the relation between the survival of patients with stage IIIB/IV nonsmall cell lung cancer (NSCLC) and pack‐years of cigarette smoking (graded according to the American Joint Committee on Cancer staging system).