ImClone's Erbitux gets FDA Priority Review: Genentech's Avastin Threatened by Competitor's Less Ghastly Side-Effects

The two currently available monoclonal antibodies being used to treat metastatic colorectal cancer, ImClone's Erbitux and Genentech's Avastin, operate very differently from one another with very different side-effects when halting progress of the disease once it has begun its spread throughout the body. And Erbitux is decidedly less onerous a treatment, making the Priority Review announcement from FDA especially important to potentially millions of cancer sufferers worldwide each year.

Erbitux slows cancer growth by targeting a protein found on the surface of some cells called the epidermal growth factor receptor while Avastin shuts down the process whereby tumors grow new blood vessels to help them receive the nutrients they need to survive and grow. But, only Avastin is currently approved by the FDA. Patients who received Avastin plus chemotherapy drugs (IFL) had an overall response rate of 39%, while the Erbitux studies showed a response rate of 21% without any chemotherapy drugs. Besides not having to go through chemo, the side effects of Erbitux are less alarming that Avastin. Erbitux has side effect like skin problems, fatigue and weakness, constipation and fever. However, Avastin, while it also has some more common and milder side effects such as those listed above, the treatment can also produce holes in the colon requiring surgical repair, heart failure, kidney damage, and the decreased ability to heal wounds.

The likely FDA action date for the supplemental biologics license application (sBLA) is early October and if the sBLA is approved, Erbitux would be the only biologic therapy to demonstrate overall survival as a single agent in patients with metastatic colorectal cancer. And, while the thought of not having to go undergo chemotherapy may be a pleasing idea to cancer patients, Genentech, the maker of Avastin, can only be more nervous about Erbitux's awaiting approval.

For background, UPI gives a nice rundown of the priority review process for Erbitux in the excerpt below:

ImClone said Monday the U.S. Food and Drug Administration granted priority review for its bid to include survival improvement on Erbitux labeling.
The company's supplemental biologics license application seeks to include evidence of improved overall survival of patients with metastatic colorectal cancer on Erbitux labeling.

If approved, the move would make Erbitux the only biologic shown to improve survival as a single agent in advanced colorectal cancer patients.

ImClone, which co-markets Erbitux with Bristol-Myers Squibb, said its request is supported by results from a phase 3 trial.

In addition to advanced colorectal cancer, Erbitux, a monoclonal antibody that inhibits a molecular structure expressed on tumor cells called the epidermal growth factor receptor, is currently approved for treating squamous cell carcinoma of the head and neck