As a flood of data comes pouring out of the American Society of Clinical Oncology meeting in Chicago, ImClone’s Erbitux has attracted much of the attention, though survival results from a lung cancer study of the drug have received a mixed response from observers.

Data from the FLEX study, conducted by Merck KGaA, the European licensee for Erbitux (cetuximab) involved 1,125 patients with newly-diagnosed advanced non-small cell lung cancer who were randomised to receive chemotherapy (cisplatin and vinorelbine) plus Erbitux or chemotherapy alone. The results demonstrated that those who received cetuximab plus chemotherapy experienced median overall survival of 11.3 months, compared with 10.1 months for those who received chemotherapy alone. The findings also showed that tumours shrank in 36.3% of patients who received the Erbitux regimen, compared with 29.2% who received chemotherapy.

This translates to Erbitux increasing overall survival by about five weeks in patients with advanced NSCLC, a result which ImClone said is statistically significant but others argue that the figures are not particularly robust. Nevertheless, ImClone and US partner Bristol-Myers Squibb will submit a supplemental biologics licence application later this year for Erbitux, which is already approved for colon and head and neck cancers, to be used in the first-line treatment of patients with NSCLC on the basis of FLEX.

Based on the results, Erbitux is now the first anti-epidermal growth factor receptor-targeted therapy to improve overall survival for NSCLC as well as the first monoclonal antibody “to improve survival across all histological subtypes, when added to platinum-based chemotherapy,” said Martin Birkhofer, vice president of oncology global medical affairs at B-MS. However his enthusiasm is not universally shared by analysts.

Eric Schmidt at Cowen & Co described the FLEX results as solid, but noted that the findings are not impressive enough to significantly affect lung cancer sales of Roche and Genentech's Avastin (bevacizumab). However he noted that doctors treating patients with NSCLC who cannot take Avastin because of side-effect issues may opt for Erbitux, which could lead to an additional $700 million in sales in the USA alone.

There was more data presented on Erbitux at ASCO, most notably another Merck-financed study called CRYSTAL which revealed that the drug does not work in patients with a gene mutation found in about 40% of colorectal tumours. However for most people who have a non-mutated version of the KRAS gene, adding Erbitux to chemotherapy cut the risk of the disease progressing by a third.