Integrating epidermal growth factor receptor-targeted therapies into platinum-based chemotherapy regimens for newly diagnosed non-small-cell lung cancer

Epidermal growth factor receptor-directed monoclonal antibodies in nonsmall cell lung cancer: an update

PURPOSE OF REVIEW

The epidermal growth factor receptor (EGFR) is overexpressed in many nonsmall cell lung cancers (NSCLCs). Blockade of EGFR by monoclonal antibodies has been studied as a strategy to improve the outcome of first-line chemotherapy in patients with NSCLC. The present review updates the findings from phase III trials.

RECENT FINDINGS

Cetuximab improved survival when combined with first-line chemotherapy and this benefit was limited to patients with high EGFR expression in their tumors. A Southwest Oncology Group study currently prospectively evaluates the predictive biomarkers for cetuximab. In the SQUIRE phase III trial, necitumumab added to cisplatin and gemcitabine increased the survival in patients with advanced squamous cell NSCLC. The INSPIRE trial studied chemotherapy with and without necitumumab in patients with nonsquamous NSCLC but was prematurely halted because of increased thromboembolic events with chemotherapy and necitumumab.

SUMMARY

EGFR monoclonal antibodies improved the outcome including survival in selected patients with advanced NSCLC. Prospective validation of predictive biomarkers is ongoing.

Cetuximab in non-small-cell lung cancer

Cetuximab is a chimeric monoclonal antibody that is directed towards the epidermal growth factor receptor (EGFR). It has been evaluated in combination with first-line chemotherapy in several phase II and two phase III trials in patients with advanced NSCLC. The phase III FLEX trial demonstrated improved survival for cetuximab combined with cisplatin plus vinorelbine compared to chemotherapy alone. The BMS099 trial failed to show a significant improvement in progression-free survival but resulted in a hazard ratio for death similar to the one seen in the FLEX trial. A meta-analysis of four randomized trials confirmed the efficacy of cetuximab when added to chemotherapy. EGFR expression levels based on an immunohistochemistry score have recently been shown to predict benefit from cetuximab in the FLEX trial. In patients with high EGFR expression, patients had prolonged survival when treated with chemotherapy plus cetuximab compared to chemotherapy alone. In patients with low EGFR expression, outcome was not different between the two treatment arms. Thus platinum-based chemotherapy combined with cetuximab represents a new treatment option for patients with advanced NSCLC and high EGFR expression in their tumors. Cetuximab is also evaluated in combination with chemoradiotherapy in patients with stage III NSCLC.

EGFR-directed monoclonal antibodies in non-small cell lung cancer: how to predict efficacy?

Cetuximab improved survival when added to first-line platinum-based chemotherapy in patients with advanced non-small cell lung cancer. In order to determine those patients who will derive the greatest benefit from the addition of cetuximab, the associations of clinical and tumor features with clinical outcome were determined. High EGFR expression of tumor cells based on an immunohistochemistry score was shown to predict benefit of cetuximab. Among patients with high EGFR expression, the hazard ratio for death was 0.73 in favor of chemotherapy plus cetuximab compared to chemotherapy alone. Among patients with low EGFR expression, no difference in survival was observed between patients treated with chemotherapy plus cetuximab compared to those treated with chemotherapy alone. The treatment interaction test was significant. KRAS mutation status and EGFR copy numbers were without predictive value. Patients with EGFR-activating mutations in their tumors had longer survival independent of the use of cetuximab. In conclusion, EGFR expression levels lend themselves as predictive biomarkers for the selection of those patients who will benefit from the addition of cetuximab to first-line chemotherapy with platinum-based doublets.

Adjuvant chemotherapy in patients with completely resected non-small cell lung cancer

Adjuvant chemotherapy has been established as a standard for patients with completely resected non-small cell lung cancer (NSCLC). Adjuvant chemotherapy increased the 5-year survival rates by 4% to 15% within randomized trials and, based on a meta-analysis of five cisplatin-based trials, by 5.4%. Adjuvant chemotherapy consists of a cisplatin-based doublet, preferentially cisplatin plus vinorelbine. Future improvements in outcome of adjuvant therapy are expected by customized chemotherapy and the integration of targeted therapies or immunotherapy.

Novel drugs against non-small-cell lung cancer

PURPOSE OF REVIEW

Important therapeutic advances for patients with advanced non-small-cell lung cancer (NSCLC) with focus on individualized therapy have recently occurred and are summarized in this review.

RECENT FINDINGS

Cetuximab added to first-line chemotherapy has been shown to improve survival in patients with high epidermal growth factor receptor (EGFR) expression in their tumors. Afatinib has shown improved progression-free survival and better quality of life compared to chemotherapy in patients with EGFR-mutation-positive adenocarcinomas. Several other EGFR-directed agents are in clinical development. Crizotinib improved progression-free survival compared to second-line chemotherapy with docetaxel or pemetrexed in patients with advanced anaplastic lymphoma kinase-positive NSCLC. Selumetinib added to docetaxel has improved outcome compared with docetaxel in a randomized phase II trial in patients with advanced KRAS-mutant NSCLC and this combination is currently studied in a phase III trial. Nintedanib added to docetaxel improved progression-free survival in the second-line therapy of patients with advanced NSCLC but many other angiogenesis inhibitors failed to improve clinical outcome in phase III trials. Several other targeted therapies are currently evaluated in phase III trials in patients with advanced NSCLC.

SUMMARY

Recent trials have led to the approval of afatinib and crizotinib for subsets of patients with advanced NSCLC.

Pooled analysis of clinical outcome for EGFR TKI-treated patients with EGFR mutation-positive NSCLC

Patients with non-small-cell lung cancer (NSCLC) appear to gain particular benefit from treatment with epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors (TKI) if their disease tests positive for EGFR activating mutations. Recently, several large, controlled, phase III studies have been published in NSCLC patients with EGFR mutation-positive tumours. Given the increased patient dataset now available, a comprehensive literature search for EGFR TKIs or chemotherapy in EGFR mutation-positive NSCLC was undertaken to update the results of a previously published pooled analysis. Pooling eligible progression-free survival (PFS) data from 27 erlotinib studies (n = 731), 54 gefitinib studies (n = 1802) and 20 chemotherapy studies (n = 984) provided median PFS values for each treatment. The pooled median PFS was: 12.4 months (95% accuracy intervals [AI] 11.6-13.4) for erlotinib-treated patients; 9.4 months (95% AI 9.0-9.8) for gefitinib-treated patients; and 5.6 months (95% AI 5.3-6.0) for chemotherapy. Both erlotinib and gefitinib resulted in significantly longer PFS than chemotherapy (permutation testing; P = 0.000 and P = 0.000, respectively). Data on more recent TKIs (afatinib, dacomitinib and icotinib) were insufficient at this time-point to carry out a pooled PFS analysis on these compounds. The results of this updated pooled analysis suggest a substantial clear PFS benefit of treating patients with EGFR mutation-positive NSCLC with erlotinib or gefitinib compared with chemotherapy.

EGFR-directed monoclonal antibodies in non-small cell lung cancer

Several monoclonal antibodies directed against the epidermal growth factor receptor (EGFR) have been evaluated in patients with non-small cell lung cancer (NSCLC). Cetuximab, a chimeric monoclonal antibody, has been studied in combination with first-line chemotherapy in phase II and two phase III trials in patients with advanced NSCLC. The phase III FLEX trial demonstrated an increase in survival for cisplatin/vinorelbine plus cetuximab compared to chemotherapy alone in patients with advanced EGFR-expressing NSCLC. Cetuximab added to carboplatin/paclitaxel failed to improve progression-free survival in the BMS099 phase III trial. However, a meta-analysis of four randomized trials confirmed a significant survival benefit for platinum-based chemotherapy plus cetuximab compared to chemotherapy alone. High EGFR expression of tumor cells was then shown to predict the benefit of cetuximab, whereas KRAS mutations and EGFR fluorescent in situ hybridization analysis were without predictive value. Matuzumab and panitumumab have also been studied in phase II trials. Necitumumab, a fully human monoclonal antibody, is currently evaluated in combination with chemotherapy in two phase III trials in patients with advanced NSCLC. Cetuximab is also studied in combination with chemoradiotherapy in patients with locally advanced NSCLC.

Comparison of KRAS and EGFR gene status between primary non-small cell lung cancer and local lymph node metastases: implications for clinical practice

Background

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) have been widely used for the treatment of non-small cell lung cancer (NSCLC). KRAS and EGFR somatic mutations in NSCLC may predict resistance and responsiveness to TKI, respectively. Nevertheless, most research to date has been conducted on samples from primary tumors. For many patients with advanced disease, their samples can only be obtained from metastases for test. The molecular characteristics of metastasized tumors may be different from those of primary tumors.

Materials and methods

Mutation status of KRAS and EGFR between primary tumors and local lymph node metastases of 80 Chinese patients with NSCLC were analyzed by direct sequencing. Five of them were given gefitinib as neoadjunvant treatment after the EGFR-TKI sensitive mutations were detected in their biopsies of mediastinal lymph nodes metastases. McNemar's test was used to compare the EGFR and KRAS mutation status between primary tumors and corresponding local lymph node metastases. Data evaluation was carried out with SPSS_13.0 statistical software.

Results

Among the 160 samples, one primary tumor and seven metastases were identified with KRAS mutations and 21 primary tumors and 26 metastases were found to have EGFR mutations. KRAS and EGFR mutation status was different between primary tumors and corresponding metastases in 6 (7.5%) and 7 (8.75%) patients, respectively. One patient with no TKI sensitive mutations detected in the primary tumor showed disease progression.

Conclusion

Our results suggest that a considerable proportion of NSCLC in Chinese population showed discrepancy in KRAS and EGFR mutation status between primary tumors and corresponding metastases. This observation may have important implication for the use of targeted TKI therapy in the treatment of NSCLC patients.

Monoclonal antibodies against EGFR in non-small cell lung cancer

Blockade of the epidermal growth factor receptor (EGFR) by monoclonal antibodies is a strategy to improve outcome in patients with non-small cell lung cancer. Cetuximab, a chimeric anti-EGFR monoclonal antibody, has been studied in combination with different chemotherapy protocols in both phase II and phase III trials in patients with advanced NSCLC. In the phase III FLEX trial, cetuximab added to cisplatin/vinorelbine resulted in an absolute overall survival benefit of 1.2 months compared to the same chemotherapy alone in patients with advanced EGFR-expressing NSCLC. In the second phase III trial, cetuximab added to carboplatin plus paclitaxed failed to improve progression-free survival but suggested a survival benefit similar to that seen in the FLEX trial. However, the benefit in survival reached statistical significance only in the FLEX trial. A meta-analysis that included patients from four randomized trials confirmed the efficacy of cetuximab when added to chemotherapy. Thus addition of cetuximab to platinum-based chemotherapy represents a new treatment option for patients with advanced NSCLC. Matuzumab and panitumumab have also been evaluated in phase II trials. Necitumumab is currently evaluated in combination with chemotherapy in two randomized phase III trials.

EGFR/KRAS/BRAF mutations in primary lung adenocarcinomas and corresponding locoregional lymph node metastases

PURPOSE

The epidermal growth factor receptor (EGFR) and its downstream factors KRAS and BRAF are mutated with different frequencies in non-small cell lung cancer and mutations predict clinical response to EGFR inhibitors. The present study compared the mutational status of EGFR, KRAS, and BRAF in primary tumors with the one in corresponding lymph node metastases.

EXPERIMENTAL DESIGN

Direct bidirectional sequencing of EGFR gene exons 18 to 21, KRAS gene codons 12/13 and 61 to 68, and BRAF exon 15 was done on 96 paired samples of primary lung adenocarcinomas and corresponding locoregional lymph node metastases. In addition, comparative genomic hybridization analyses in two pairs of corresponding primary and metastatic tumor samples with discordant EGFR mutation status were done.

RESULTS

Mutations in EGFR, KRAS, and BRAF were observed in 7 (7%), 36 (38%), and 2 (2%) patients, respectively. Interestingly, KRAS mutations were observed in two patients with an EGFR mutation. Mutations in primary tumors and lymph node metastases were identical in 1 of 7 (14%) patients in case of EGFR and 11 of 36 (31%) patients in case of KRAS. One patient harbored different KRAS mutations in primary and corresponding metastatic tumors. Comparative genomic hybridization analysis revealed similar patterns of chromosomal changes, strongly supporting a common clonal origin of primary tumors and metastases.

CONCLUSIONS

The possibility of differences in the mutational status of EGFR, KRAS, BRAF between primary tumors and corresponding lymph node metastases should be considered whenever these mutations are used for the selection of patients for EGFR-directed tyrosine kinase inhibitor therapy.