Shares in US biotech ImClone Systems fell on Tuesday after a highly-anticipated trial of its cancer drug Erbitux (cetuximab) in pancreatic cancer failed to live up to expectations.
The news comes as a blow to patients suffering from pancreatic cancer, who desperately need improved therapies for a disease that has a five-year survival rate of just 5 per cent. But the company still believes Erbitux could have a role to play in treating the disease.
Although already on the market for colorectal and head and neck cancer, the Phase III trial in pancreatic cancer was considered a real opportunity to add some new sales momentum to Erbitux, currently its only marketed product.
Estimates are that the market for pancreatic cancer would be roughly equivalent to that of head and neck cancer in terms of patient numbers, but given the lack of effective treatments penetration of a new option would likely be swift.
Erbitux failed to meet the primary objective of extending overall survival in the trial, which looked at the benefit of adding the biologic to standard treatment with Eli Lilly's Gemzar (gemcitabine).
But ImClone and its co-marketing partner for the drug, Bristol-Myers Squibb, insisted they were not giving hope and would continue to test it as a combination therapy in pancreatic cancer.
A spokesperson for ImClone said there are a number of trials ongoing on the use of Erbitux and a rival colorectal cancer treatment, Genentech/Roche's Avastin (bevacizumab), in pancreatic cancer patients.
Avastin has a different mechanism of action to Erbitux, and ImClone is optimistic that giving the two drugs in combination could be the key to unlocking the efficacy of its product in pancreatic cancer.
These trials include: IMCL-055, looking at Erbitux/Avastin plus Gemzar; ECOG 8200, which is investigating Erbitux use alongside chemotherapy with irinotecan and docetaxel; and NCI-6580, which will assess Avastin and Gemzar with either Erbitux or another recently-launched pancreatic cancer drug, Genentech/Roche's Tarceva (erlotinib).
Since launching the drug in 2004, ImClone and BMS have been able to coax healthy sales out of Erbitux, topping $1 billion last year. Analysts have suggested that extending Erbitux' uses into pancreatic cancer could boost its peak sales by upwards of $250 million a year.
Conversely, the failure of the trial could also peg back Erbitux' growth as a portion of the drug's sales - perhaps as much as $50 million - is estimated to come from off-label use in these patients. It also raises questions about how effective Erbitux may be in other follow-up indications such as lung cancer.
Meantime, Erbitux recently started to face competition in colorectal cancer treatment from Amgen's Vectibix (panitumumab) which was launched in the US last September.
Both Erbitux and Vectibix work by blocking the epidermal growth factor receptor (EGFr) which is over-expressed in a number of solid tumours, while Avastin targets the receptor for vascular endothelial growth factor (VEGF).
Since launching its drug in the US, Amgen has thrown down the gauntlet to ImClone and B-MS, positioning Vectibix as a lower-cost alternative to Erbitux via substantial discounting and price-capping incentives for patients funding their own treatment. This is despite the fact that the two have different approved uses, with Vectibix used as a third-line therapy for colorectal cancer, and Erbitux cleared as a second-line treatment in combination with chemotherapy.
Amgen suffered its own disappointment for Vectibix last month after the drug failed to show an increase in efficacy in combination with Avastin and chemotherapy as a first-line treatment for colorectal cancer, but has already got off to a promising start commercially with its approved use. It grabbed just under $40 million in sales in its first three months on the US market, helped by off-label use as a second-line treatment.
In Europe, Erbitux is sold by German pharmaceutical and chemical firm Merck KGaA, which reported that turnover of the drug in 2006 climbed 55 per cent to €337 million. Shares in Merck also dipped on news of the pancreatic cancer trial disappointment.