The clinical effectiveness and cost-effectiveness of cetuximab (review of technology appraisal no. 176) and panitumumab (partial review of technology appraisal no. 240) for previously untreated metastatic colorectal cancer: a systematic review and economic evaluation

BACKGROUND

Colorectal cancer is the fourth most commonly diagnosed cancer in the UK after breast, lung and prostate cancer. People with metastatic disease who are sufficiently fit are usually treated with active chemotherapy as first- or second-line therapy. Targeted agents are available, including the antiepidermal growth factor receptor (EGFR) agents cetuximab (Erbitux^®, Merck Serono UK Ltd, Feltham, UK) and panitumumab (Vecitibix^®, Amgen UK Ltd, Cambridge, UK).

OBJECTIVE

To investigate the clinical effectiveness and cost-effectiveness of panitumumab in combination with chemotherapy and cetuximab in combination with chemotherapy for rat sarcoma (RAS) wild-type (WT) patients for the first-line treatment of metastatic colorectal cancer.

DATA SOURCES

The assessment included 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 up to 27 April 2015 in a range of electronic databases, including MEDLINE, EMBASE and The Cochrane Library.

REVIEW METHODS

Studies were included if they were randomised controlled trials (RCTs) or systematic reviews of RCTs of cetuximab or panitumumab in participants with previously untreated metastatic colorectal cancer with RAS WT status. All steps in the review were performed by one reviewer and checked independently by a second. Narrative synthesis and network meta-analyses (NMAs) were conducted for outcomes of interest. An economic model was developed focusing on first-line treatment and using a 30-year time horizon to capture costs and benefits. Costs and benefits were discounted at 3.5% per annum. Scenario analyses and probabilistic and univariate deterministic sensitivity analyses were performed.

RESULTS

The searches identified 2811 titles and abstracts, of which five clinical trials were included. Additional data from these trials were provided by the manufacturers. No data were available for panitumumab plus irinotecan-based chemotherapy (folinic acid + 5-fluorouracil + irinotecan) (FOLFIRI) in previously untreated patients. Studies reported results for RAS WT subgroups. First-line treatment with anti-EGFR therapies in combination with chemotherapy appeared to have statistically significant benefits for patients who are RAS WT. For the independent economic evaluation, the base-case incremental cost-effectiveness ratio (ICER) for RAS WT patients for cetuximab plus oxaliplatin-based chemotherapy (folinic acid + 5-fluorouracil + oxaliplatin) (FOLFOX) compared with FOLFOX was £104,205 per quality-adjusted life-year (QALY) gained; for panitumumab plus FOLFOX compared with FOLFOX was £204,103 per QALY gained; and for cetuximab plus FOLFIRI compared with FOLFIRI was £122,554 per QALY gained. The ICERs were sensitive to treatment duration, progression-free survival, overall survival (resected patients only) and resection rates.

LIMITATIONS

The trials included RAS WT populations only as subgroups. No evidence was available for panitumumab plus FOLFIRI. Two networks were used for the NMA and model, based on the different chemotherapies (FOLFOX and FOLFIRI), as insufficient evidence was available to the assessment group to connect these networks.

CONCLUSIONS

Although cetuximab and panitumumab in combination with chemotherapy appear to be clinically beneficial for RAS WT patients compared with chemotherapy alone, 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 in patients with RAS WT.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015016111.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Epidermal growth factor receptor (EGFR) inhibitors for metastatic colorectal cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) inhibitors prevent cell growth and have shown benefit in the treatment of metastatic colorectal cancer, whether used as single agents or in combination with chemotherapy. Clear benefit has been shown in trials of EGFR monoclonal antibodies (EGFR MAb) but not EGFR tyrosine kinase inhibitors (EGFR TKI). However, there is ongoing debate as to which patient populations gain maximum benefit from EGFR inhibition and where they should be used in the metastatic colorectal cancer treatment paradigm to maximise efficacy and minimise toxicity.

OBJECTIVES

To determine the efficacy, safety profile, and potential harms of EGFR inhibitors in the treatment of people with metastatic colorectal cancer when given alone, in combination with chemotherapy, or with other biological agents.The primary outcome of interest was progression-free survival; secondary outcomes included overall survival, tumour response rate, quality of life, and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library, Issue 9, 2016; Ovid MEDLINE (from 1950); and Ovid Embase (from 1974) on 9 September 2016; and ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) on 14 March 2017. We also searched proceedings from the major oncology conferences ESMO, ASCO, and ASCO GI from 2012 to December 2016. We further scanned reference lists from eligible publications and contacted corresponding authors for trials for further information where needed.

SELECTION CRITERIA

We included randomised controlled trials on participants with metastatic colorectal cancer comparing: 1) the combination of EGFR MAb and 'standard therapy' (whether chemotherapy or best supportive care) to standard therapy alone, 2) the combination of EGFR TKI and standard therapy to standard therapy alone, 3) the combination of EGFR inhibitor (whether MAb or TKI) and standard therapy to another EGFR inhibitor (or the same inhibitor with a different dosing regimen) and standard therapy, or 4) the combination of EGFR inhibitor (whether MAb or TKI), anti-angiogenic therapy, and standard therapy to anti-angiogenic therapy and standard therapy alone.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures defined by Cochrane. Summary statistics for the endpoints used hazard ratios (HR) with 95% confidence intervals (CI) for overall survival and progression-free survival, and odds ratios (OR) for response rate (RR) and toxicity. Subgroup analyses were performed by Kirsten rat sarcoma viral oncogene homolog (KRAS) and neuroblastoma RAS viral (V-Ras) oncogene homolog (NRAS) status - firstly by status of KRAS exon 2 testing (mutant or wild type) and also by status of extended KRAS/NRAS testing (any mutation present or wild type).

MAIN RESULTS

We identified 33 randomised controlled trials for analysis (15,025 participants), including trials of both EGFR MAb and EGFR TKI. Looking across studies, significant risk of bias was present, particularly with regard to the risk of selection bias (15/33 unclear risk, 1/33 high risk), performance bias (9/33 unclear risk, 9/33 high risk), and detection bias (7/33 unclear risk, 11/33 high risk).The addition of EGFR MAb to standard therapy in the KRAS exon 2 wild-type population improves progression-free survival (HR 0.70, 95% CI 0.60 to 0.82; high-quality evidence), overall survival (HR 0.88, 95% CI 0.80 to 0.98; high-quality evidence), and response rate (OR 2.41, 95% CI 1.70 to 3.41; high-quality evidence). We noted evidence of significant statistical heterogeneity in all three of these analyses (progression-free survival: I2 = 76%; overall survival: I2 = 40%; and response rate: I2 = 77%), likely due to pooling of studies investigating EGFR MAb use in different lines of therapy. Rates of overall grade 3 to 4 toxicity, diarrhoea, and rash were increased (moderate-quality evidence for all three outcomes), but there was no evidence for increased rates of neutropenia.For the extended RAS wild-type population (no mutations in KRAS or NRAS), addition of EGFR MAb improved progression-free survival (HR 0.60, 95% CI 0.48 to 0.75; moderate-quality evidence) and overall survival (HR 0.77, 95% CI 0.67 to 0.88; high-quality evidence). Response rate was also improved (OR 4.28, 95% CI 2.61 to 7.03; moderate-quality evidence). We noted significant statistical heterogeneity in the progression-free survival analysis (I2 = 61%), likely due to the pooling of studies combining EGFR MAb with chemotherapy with monotherapy studies.We observed no evidence of a statistically significant difference when EGFR MAb was compared to bevacizumab, in progression-free survival (HR 1.02, 95% CI 0.93 to 1.12; high quality evidence) or overall survival (HR 0.84, 95% CI 0.70 to 1.01; moderate-quality evidence). We noted significant statistical heterogeneity in the overall survival analysis (I2 = 51%), likely due to the pooling of first-line and second-line studies.The addition of EGFR TKI to standard therapy in molecularly unselected participants did not show benefit in limited data sets (meta-analysis not performed). The addition of EGFR MAb to bevacizumab plus chemotherapy in people with KRAS exon 2 wild-type metastatic colorectal cancer did not improve progression-free survival (HR 1.04, 95% CI 0.83 to 1.29; very low quality evidence), overall survival (HR 1.00, 95% CI 0.69 to 1.47; low-quality evidence), or response rate (OR 1.20, 95% CI 0.67 to 2.12; very low-quality evidence) but increased toxicity (OR 2.57, 95% CI 1.45 to 4.57; low-quality evidence). We noted significant between-study heterogeneity in most analyses.Scant information on quality of life was reported in the identified studies.

AUTHORS' CONCLUSIONS

The addition of EGFR MAb to either chemotherapy or best supportive care improves progression-free survival (moderate- to high-quality evidence), overall survival (high-quality evidence), and tumour response rate (moderate- to high-quality evidence), but may increase toxicity in people with KRAS exon 2 wild-type or extended RAS wild-type metastatic colorectal cancer (moderate-quality evidence). The addition of EGFR TKI to standard therapy does not improve clinical outcomes. EGFR MAb combined with bevacizumab is of no clinical value (very low-quality evidence). Future studies should focus on optimal sequencing and predictive biomarkers and collect quality of life data.