Cetuximab: a new treatment for advanced non-small cell lung cancer

Lung cancer is the most common cancer in the world. Advanced non-small cell lung cancer (NSCLC) accounts for about 60% of all lung cancer cases. Since the effectiveness of current standard treatment for advanced NSCLC (i.e. chemotherapy) has reached a ceiling, there is a continuous need for new, more effective treatments to further improve the outcome of patients with the disease. This review of 2018 patients, from four trials, found that adding cetuximab (a newly developed agent) to standard treatment, prolonged the survival time of advanced NSCLC patients by about 1.5 months, and deferred the progression of cancer by about 0.5 month. One year after the treatment, 45% of the patients receiving standard treatment plus cetuximab, and 40% of the patients receiving standard treatment alone were still alive. However, the effects of cetuximab on quality of life of patients were uncertain. Seven types of adverse events, mainly involving skin and blood, occurred much more in the patients receiving cetuximab, while other adverse events seemed to occur equally in both groups. The adverse events were reported as generally manageable. No deaths related to cetuximab were reported. In summary, high quality evidence shows that the use of cetuximab combined with standard treatment leads to better survival than standard treatment alone, in improving survival of patients with advanced NSCLC.

Authors' conclusions: 

The combination of chemotherapy plus cetuximab is better than chemotherapy alone as the first-line treatment of advanced NSCLC in improving overall survival, while inducing higher rates of some reportedly manageable adverse events.

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Background: 

In advanced non-small cell lung cancer (NSCLC), the effectiveness of standard cytotoxic chemotherapy seems to have reached a 'plateau', and there is a continuous need for new treatments to further improve the prognosis. Cetuximab is a monoclonal antibody targeted at the epidermal growth factor receptor (EGFR) signalling pathway. Basically, it is designed to inhibit the growth and metastasis among other biological processes of cancer. In combination with chemotherapy, it has been evaluated as a first-line treatment for advanced NSCLC in some randomised controlled trials (RCTs), with inconsistent results.

Objectives: 

To evaluate the efficacy and toxicity of chemotherapy plus cetuximab, compared with chemotherapy alone, for advanced non-small cell lung cancer (NSCLC) previously untreated with chemotherapy or epidermal growth factor receptor (EGFR)-targeted drugs.

Search strategy: 

We systematically searched the Cochrane Lung Cancer Review Group's Specialized Register (from inception to 17 December 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE (accessed through PubMed, 1966 to 17 December 2013), EMBASE (1980 to 17 December 2013), ClinicalTrials.gov (from inception to 17 December 2013), and the World Health Organization (WHO) International Clinical Trials Registry Platform (from inception to 17 December 2013). We also handsearched the proceedings related to lung cancer from the American Society of Clinical Oncology and European Society of Medical Oncology (2000 to 17 December 2013). We checked the reference lists of all eligible primary studies and review articles for additional potentially eligible studies.

Selection criteria: 

Eligible studies were RCTs that compared chemotherapy plus cetuximab with the same chemotherapy alone, in advanced NSCLC, previously untreated with chemotherapy or EGFR-targeted drugs, and measured at least one of the following: overall survival, progression-free survival, one-year survival rate, objective response rate, quality of life, or serious adverse events.

Data collection and analysis: 

We used standard methodological procedures expected by The Cochrane Collaboration. We extracted the following data from each study: publication details, participant characteristics, regimens for intervention and control arms, outcome measures and effect size, and information related to the methodological quality of the study. We measured the treatment effects on dichotomous and time-to-event outcomes by risk ratio (RR) and hazard ratio (HR), with 95% confidence intervals (CIs), respectively. We conducted meta-analyses with Review Manager 5 using the random-effects model. We employed the Mantel-Haenszel method to combine RRs and the inverse-variance method to combine HRs.

Main results: 

We included four trials, containing 2018 patients. The subjects were mostly white people (female: 26% to 56%), with a median age of 58 to 66 years. About half of them had histologically proven adenocarcinoma. Of the 2018 patients, 83% to 99% had their status measured using the Eastern Cooperative Oncology Group performance status, and had a score of 0 to 1 (which is usually considered as physically "fit").

All four studies provided data on overall survival, progression-free survival, one-year survival rate, objective response rate, and serious adverse events, with two studies (1901 patients) investigating the effect of cetuximab on quality of life as well. The risk of bias was low for the data on overall survival and one-year survival rate, and high for the data on all other outcomes, mainly due to lack of blinding. Compared with chemotherapy alone, chemotherapy plus cetuximab improved overall survival (10.5 months versus 8.9 months; HR 0.87, 95% CI 0.79 to 0.96), one-year survival rate (45% versus 40%; RR 1.13, 95% CI 1.02 to 1.25), and objective response rate (30% versus 23%; RR 1.31, 95% CI 1.14 to 1.51). The difference in progression-free survival was at the limit of the statistical significance (4.9 months versus 4.4 months; HR 0.91, 95% CI 0.83 to 1.00). No significant difference in quality of life between the two treatment arms was reported by the two relevant studies. Patients in the cetuximab group experienced more acneiform rash (11.2% versus 0.3%; RR 37.36, 95% CI 10.66 to 130.95), hypomagnesemia (5.3% versus 0.8%; RR 6.57, 95% CI 1.13 to 38.12), infusion reaction (3.9% versus 1.1%; RR 3.50, 95% CI 1.76 to 6.94), diarrhoea (4.8% versus 2.3%; RR 2.10, 95% CI 1.26 to 3.48), hypokalaemia (6.3% versus 3.6%; RR 1.74, 95% CI 1.02 to 2.99), febrile neutropenia (10.6% versus 7.6%; RR 1.40, 95% CI 1.10 to 1.77), and leukopenia (58.1% versus 42.7%; RR 1.36, 95% CI 1.17 to 1.58) than did those in the control group. The difference in other adverse events did not reach statistical significance. According to the reports of original studies, the adverse events were generally manageable. There were no cetuximab-related deaths.

The quality of the evidence is high for overall survival and one-year survival rate, but low for most secondary outcomes.

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