Vectibix, a drug developed by Amgen that is expected to make significant gains in the market for colorectal cancer drugs, has won approval in the USA, its first market.
Vectibix (panitumumab) is an epidermal growth factor receptor (EGFr) inhibitor and will eventually compete with another drug in this class, Erbitux from ImClone Systems and Bristol Myers Squibb.
For the moment, Vectibix is approved as a third-line monotherapy for colorectal cancer, while Erbitux is approved for use as a first-line treatment in combination with chemotherapy. But Amgen is determined to expand the use of its drug into the adjuvant setting, which could drive peak sales into blockbuster territory and place it head-to-head with Erbitux.
With current therapies, almost all colorectal cancer patients experience progressive disease after second-line therapy, so even with third-line labelling Vectibix is expected to secure sales in excess of $750 million, according to analysts.
Amgen is due to report data from trials looking at first-line treatment with Vectibix and Roche’s Avastin (bevacizumab) early next year, with additional studies planned in other combinations and in other tumour types.
That course of action that could have set it on course for an intellectual property dispute with ImClone. But a court stripped ImClone of rights to a US patent covering the use of EGFr inhibitors alongside chemotherapy last week and awarded ownership instead to an Israeli company. Amgen was swift to negotiate its own licensing agreement for the disputed patent with the new holder, Yeda Research and Development Co, removing a potential block to commercialisation of Vectibix.
Announcing the approval yesterday, Amgen was quick to throw down the gauntlet to its rival and said it would launch Vectibix at a 20% discount to Erbitux, roughly $8,000 per month.
Even without the lower price, Vectibix is expected to mount strong competition to Erbitux because it is a fully-human antibody, which theoretically means that it is less prone to infusion reactions and allergic side effects than ImClone's product. It is dosed once every two weeks, while Erbitux is given weekly.
The FDA approved Vectibix on the basis of the results of a clinical trial of 463 metastatic colorectal cancer patients who had already undergone treatment with fluoropyrimidine, oxaliplatin and irinotecan-based chemotherapy.
The mean time to disease progression or death in patients receiving Vectibix was 96 days versus 60 days in patients receiving the best standard supportive care. In addition, 8% of the patients on Vectibix experienced a tumour shrinkage that in some cases exceeded 50% of the pre-treatment size.
Both study groups showed similar overall survival. As a condition of approval Amgen has committed to a post-marketing trial to show whether the drug improves patients’ survival in patients with fewer prior chemotherapies.
The company also said it would set up a financial assistance programme that would include a cap on out-of-pocket expenses for patients receiving the drug at 5% of their gross income, as well as treatment at no cost to qualifying uninsured patients.