Bristol-Myers Squibb (BMS) and Eli Lilly have won US approval for the use of Erbitux as a first-line treatment for patients with metastatic colorectal cancer who test positive for a genetic biomarker.
The US Food and Drug Administration (FDA) cleared Erbitux (cetuximab) for the new indication whilst also giving a green light to Qiagen's therascreen KRAS RGQ test, a polymerase chain reaction (PCR) companion diagnostic that will help predict whether a patient will respond to treatment with the drug.
The test is used to determine whether patients have mutations in the KRAS gene, a group which makes up around 40 per cent of colorectal cancer cases.
Earlier studies have shown that KRAS-positive patients do not tend to respond to Erbitux treatment, as the mutation bypasses the molecular blockade imposed by the epidermal growth factor receptor (EGFR) inhibitor on cancer cells.
Erbitux was first approved in the US in 2004 for all colorectal cancer patients whose tumours expressed EGFR, but its labelling was narrowed in 2009 after the effects of the KRAS mutation became known.
BMS and Lilly carried out testing on tumour biopsies collected in the pivotal trials programme for Erbitux using Qiagen's genetic test, and found that KRAS-negative patients lived for a median of 8.6 months with Erbitux treatment, while those with the mutation lived for around 5 months.
The new Erbitux indication is for first-line use of the drug alongside chemotherapy with irinotecan, 5-fluorouracil and leucovorin (FOLFIRI) with EGFR-positive and KRAS-negative tumours.
The news is a boost for Erbitux' developers, which have struggled to get approval for new indications for the drug beyond its established uses in colorectal and head and neck cancer.
Just last week, Erbitux' European marketer Merck KGaA announced disappointing results in a phase III trial of the drug in gastric cancer. Meanwhile earlier studies looking at its use in the adjuvant setting in colorectal cancer and in non-small cell lung cancer (NSCLC) were also negative.
Analysts said the use in first-line colorectal cancer would not lead to a significant boost in sales, however, as other tests are available for KRAS mutations and are already used off-label by some oncologists to gauge whether patients should be treated with Erbitux and other EGFR inhibitors such as Amgen/Takeda's Vectibix (panitumumab).