Abstract
BACKGROUND
Epidermal growth factor receptor (EGFR) mutation positive (M+) non-small cell lung cancer (NSCLC) is an important subtype of lung cancer comprising 10% to 15% of non-squamous tumours. This subtype is more common in women than men, is less associated with smoking, but occurs at a younger age than sporadic tumours.
OBJECTIVES
To assess the clinical effectiveness of single-agent or combination EGFR therapies used in the first-line treatment of people with locally advanced or metastatic EGFR M+ NSCLC compared with other cytotoxic chemotherapy (CTX) agents used alone or in combination, or best supportive care (BSC). The primary outcomes were overall survival and progression-free survival. Secondary outcomes included response rate, symptom palliation, toxicity, and health-related quality of life.
SEARCH METHODS
We conducted electronic searches of the Cochrane Register of Controlled Trials (CENTRAL) (2020, Issue 7), MEDLINE (1946 to 27th July 2020), Embase (1980 to 27th July 2020), and ISI Web of Science (1899 to 27th July 2020). We also searched the conference abstracts of the American Society for Clinical Oncology and the European Society for Medical Oncology (July 2020); Evidence Review Group submissions to the National Institute for Health and Care Excellence; and the reference lists of retrieved articles.
SELECTION CRITERIA
Parallel-group randomised controlled trials comparing EGFR-targeted agents (alone or in combination with cytotoxic agents or BSC) with cytotoxic chemotherapy (single or doublet) or BSC in chemotherapy-naive patients with locally advanced or metastatic (stage IIIB or IV) EGFR M+ NSCLC unsuitable for treatment with curative intent.
DATA COLLECTION AND ANALYSIS
Two review authors independently identified articles, extracted data, and carried out the 'Risk of bias' assessment. We conducted meta-analyses using a fixed-effect model unless there was substantial heterogeneity, in which case we also performed a random-effects analysis as a sensitivity analysis.
MAIN RESULTS
Twenty-two trials met the inclusion criteria. Ten of these exclusively recruited people with EGFR M+ NSCLC; the remainder recruited a mixed population and reported results for people with EGFR M+ NSCLC as subgroup analyses. The number of participants with EGFR M+ tumours totalled 3023, of whom approximately 2563 were of Asian origin. Overall survival (OS) data showed inconsistent results between the included trials that compared EGFR-targeted treatments against cytotoxic chemotherapy or placebo. Erlotinib was used in eight trials, gefitinib in nine trials, afatinib in two trials, cetuximab in two trials, and icotinib in one trial. The findings of FASTACT 2 suggested a clinical benefit for OS for participants treated with erlotinib plus cytotoxic chemotherapy when compared to cytotoxic chemotherapy alone, as did the Han 2017 trial for gefitinib plus cytotoxic chemotherapy, but both results were based on a small number of participants (n = 97 and 122, respectively). For progression-free survival (PFS), a pooled analysis of four trials showed evidence of clinical benefit for erlotinib compared with cytotoxic chemotherapy (hazard ratio (HR) 0.31; 95% confidence interval (CI) 0.25 to 0.39 ; 583 participants ; high-certainty evidence). A pooled analysis of two trials of gefitinib versus paclitaxel plus carboplatin showed evidence of clinical benefit for PFS for gefitinib (HR 0.39; 95% CI 0.32 to 0.48 ; 491 participants high-certainty evidence), and a pooled analysis of two trials of gefitinib versus pemetrexed plus carboplatin with pemetrexed maintenance also showed evidence of clinical benefit for PFS for gefitinib (HR 0.59; 95% CI 0.46 to 0.74, 371 participants ; moderate-certainty evidence). Afatinib showed evidence of clinical benefit for PFS when compared with chemotherapy in a pooled analysis of two trials (HR 0.42; 95% CI 0.34 to 0.53, 709 participants high-certainty evidence). All but one small trial showed a corresponding improvement in response rate with tyrosine-kinase inhibitor (TKI) compared to chemotherapy. Commonly reported grade 3/4 adverse events associated with afatinib, erlotinib, gefitinib and icotinib monotherapy were rash and diarrhoea. Myelosuppression was consistently worse in the chemotherapy arms; fatigue and anorexia were also associated with some chemotherapies. Seven trials reported on health-related quality of life and symptom improvement using different methodologies. For each of erlotinib, gefitinib, and afatinib, two trials showed improvement in one or more indices for the TKI compared to chemotherapy. The quality of evidence was high for the comparisons of erlotinib and gefitinib with cytotoxic chemotherapy and for the comparison of afatinib with cytotoxic chemotherapy.
AUTHORS' CONCLUSIONS
Erlotinib, gefitinib, afatinib and icotinib are all active agents in EGFR M+ NSCLC patients, and demonstrate an increased tumour response rate and prolonged PFS compared to cytotoxic chemotherapy. We found a beneficial effect of the TKI compared to cytotoxic chemotherapy in adverse effect and health-related quality of life. We found limited evidence for increased OS for the TKI when compared with standard chemotherapy, but the majority of the included trials allowed participants to switch treatments on disease progression, which will have a confounding effect on any OS analysis. Single agent-TKI remains the standard of care and the benefit of combining a TKI and chemotherapy remains uncertain as the evidence is based on small patient numbers. Cytotoxic chemotherapy is less effective in EGFR M+ NSCLC than erlotinib, gefitinib, afatinib or icotinib and is associated with greater toxicity. There are no data supporting the use of monoclonal antibody therapy. Icotinib is not available outside China.
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