Bokemeyer OPUS 2009.

Methods	Phase II open‐label RCT; n = 338
Participants	Nonresectable metastatic CRC
Interventions	FOLFOX4 with cetuximab versus FOLFOX4
Outcomes	Primary endpoint: tumour response rate. Secondary endpoints: exploratory only
Notes	Funded by Merck KGaA. Funding: Bokemeyer: consultant/advisory role (Merck Serono), honoraria (Merck Serono, Sanofi‐Aventis), research funding (Merck Serono); Koralewski: none declared. Follow‐up: 44.1 months (cetuximab arm), 31.8 months (standard arm)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation (1:1) was carried out using a stratified permuted‐block procedure, with ECOG PS (0 and 1 vs 2) as a stratification factor.
Allocation concealment (selection bias)	Unclear risk	No details provided.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Open‐label trial (but blinded review for primary outcome; see below)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The independent review committee conducted a blinded review of images and clinical data using a common set of prespecified criteria.
Incomplete outcome data (attrition bias) All outcomes	Low risk	1/170 dropout in experimental arm, 0/168 in control arm
Selective reporting (reporting bias)	Low risk	All stated outcomes reported.
Other bias	Low risk	No other significant bias present; funders did not have inappropriate influence.