Abstract
Background:
Colorectal cancer is the third most commonly diagnosed cancer in the UK after breast and lung cancer. People with metastatic disease who are sufficiently fit are usually treated with active chemotherapy as first- or second-line therapy. Recently, targeted agents have become available including anti-epidermal growth factor receptor (EGFR) agents, for example cetuximab and panitumumab, and anti-vascular endothelial growth factor (VEGF) receptor agents, for example bevacizumab.
Objective:
To investigate the clinical effectiveness and cost-effectiveness of panitumumab monotherapy and cetuximab (mono- or combination chemotherapy) for Kirsten rat sarcoma (KRAS) wild-type (WT) patients, and bevacizumab in combination with non-oxaliplatin chemotherapy, for the treatment of metastatic colorectal cancer after first-line chemotherapy.
Data sources:
The assessment comprises a systematic review of clinical effectiveness and cost-effectiveness studies, a review and critique of manufacturer submissions and a de novo cohort-based economic analysis. For the assessment of effectiveness, a literature search was conducted in a range of electronic databases, including MEDLINE, EMBASE and The Cochrane Library, from 2005 to November 2010.
Review methods:
Studies were included if they were randomised controlled trials (RCTs) or systematic reviews of RCTs of cetuximab, bevacizumab or panitumumab in participants with EGFR-expressing metastatic colorectal cancer with KRAS WT status that has progressed after first-line chemotherapy (for cetuximab and panitumumab) or participants with metastatic colorectal cancer that has progressed after first-line chemotherapy (bevacizumab). All steps in the review were performed by one reviewer and checked independently by a second. Synthesis was mainly narrative. An economic model was developed focusing on third-line and subsequent lines of treatment. Costs and benefits were discounted at 3.5% per annum. Probabilistic and univariate deterministic sensitivity analyses were performed.
Results:
The searches identified 7745 titles and abstracts. Two clinical trials (reported in 12 papers) were included. No data were available for bevacizumab in combination with non-oxaliplatin-based chemotherapy in previously treated patients. Neither of the included studies had KRAS status performed prospectively, but the studies did report retrospective analyses of the results for the KRAS WT subgroups. Third-line treatment with cetuximab plus best supportive care or panitumumab plus best supportive care appears to have statistically significant advantages over treatment with best supportive care alone in patients with KRAS WT status. For the economic evaluation, five studies met the inclusion criteria. The base-case incremental cost-effectiveness ratio (ICER) for KRAS WT patients for cetuximab compared with best supportive care is £98,000 per quality-adjusted life-year (QALY), for panitumumab compared with best supportive care is £150,000 per QALY and for cetuximab plus irinotecan compared with best supportive care is £88,000 per QALY. All ICERs are sensitive to treatment duration.
Limitations:
In the specific populations of interest, there is a lack of evidence on bevacizumab, cetuximab and cetuximab plus irinotecan used second line and on bevacizumab and cetuximab plus irinotecan used third line. For cetuximab plus irinotecan treatment for KRAS WT people, there is no direct evidence on progression-free survival, overall survival and duration of treatment.
Conclusions:
Although cetuximab and panitumumab appear to be clinically beneficial for KRAS WT patients compared with best supportive care, they are likely to represent poor value for money when judged by cost-effectiveness criteria currently used in the UK. It would be useful to conduct a RCT for patients with KRAS WT status receiving cetuximab plus irinotecan.
Funding:
The National Institute for Health Research Health Technology Assessment programme.
