Final results from the CRYSTAL (Cetuximab combined with iRinotecan in first line therapY for metaSTatic colorectAL cancer) study, evaluating the addition of cetuximab (Erbitux®) to FOLFIRI chemotherapy in the first-line treatment of metastatic colorectal cancer (mCRC), have been presented at the ASCO 2010 Gastrointestinal Cancers Symposium (ASCO-GI).

In patients with KRAS wild-type tumours (n=666), the main findings were as follows (taken from the attached press release):

• Median overall survival (OS) was 23.5 months in those randomised to cetuximab plus FOLFIRI compared to 20.0 months in those receiving chemotherapy alone (Hazard Ratio [HR] 0.796; p=0.0093)

• The overall response rate (ORR) was 61.0% vs. 42.6%, respectively (p<0.0001)

• The addition of cetuximab to FOLFIRI increased progression-free survival by 2.1 months (10.9 months vs. 8.8 months; p=0.0016).  The risk of disease progression was reduced by 30.4% (HR 0.696; p=0.0012)

The final results from CRYSTAL included an analysis of the predictive value of BRAF status on cetuximab efficacy (n=59).  The results of this suggest that BRAF is not predictive for cetuximab efficacy, as patients with KRAS wild-type tumours bearing a BRAF mutation also benefited from treatment.

Updated results from patients with KRAS wild-type tumours enrolled in the OPUS  (OxaliPlatin and cetUximab in firSt-line treatment of mCRC) study (n=82) were also presented.  These showed that median OS was prolonged, but not statistically significantly so, in patients randomised to receive cetuximab plus FOLFOX4 (22.8 months versus 18.5 months in the FOLFOX4 arm; HR 0.855; p=0.3854).  The respective ORR were 57.3% and 34.0% (p=0.0027).

Finally, the authors presented the results of a pooled analysis which included all patients with KRAS wild-type mCRC enrolled in the CRYSTAL and OPUS trials (n=845).  The results for the combined study population were as follows (taken from the press release):

• The risk of death (HR 0.81; p=0.0062) and disease progression (HR 0.66; p<0.0001) were lower for patients receiving cetuximab plus FOLFIRI compared to patients receiving chemotherapy alone

• The overall response rate was 57.3% vs. 38.5%, respectively (p<0.0001)