written by guest blogger Ed Kissel, Vice President of Quantitative Analysis
In July 2010, an advisory panel voted 12-1 to urge the FDA to withdraw the approved use of Avastin in metastatic HER2-negative breast cancer. As a result of this announcement, IntrinsiQ hypothesized that physicians would immediately decrease the use the drug in new patients. We also believed that physicians would continue the course of therapy in existing patients, drawing out the decline we would see in Avastin sales. In fact, within the first three months after the advisory panel’s announcement, the usage of Avastin dropped across all lines of therapy as physicians grew reluctant to prescribe the drug when choosing their next course of therapy.
Prior to the public chatter on the FDA review, Avastin was selling approximately $160-$180MM per quarter in the U.S. breast cancer market. These sales were divided practically evenly by metastatic line of therapy. IntrinsiQ estimated the initial market event was significant enough to adversely affect Avastin sales in this tumor. We publicly reported that around $60MM per quarter would be lost within the next three months, but the decline would lose considerable momentum prior to any official FDA decision. A retrospective analysis looking at Avastin clearly shows that sales dropped as expected. IntrinsiQ’s extensive library of oncology market analogs will often show that commonly-believed benign market events (like FDA reviews for approved drugs) are often important enough to reduce sales up to 60% practically overnight.
Unfortunately for other products in the breast cancer market, this does not necessarily open the door for new therapies. We believe that there is no real replacement for Avastin in breast cancer in today’s market. Avastin is primarily seen as an add-on therapy and didn’t replace anything at launch. We believe that the market will revert back to historical usage patterns, or taxanemonotherapy and combination use without adding Avastin.
In December 2010, the FDA moved to withdraw the approval of Avastin in metastatic HER2-negative breast cancer based on the lack of clinical benefit shown in the trial data. We are not in the right position to provide the clinical insight into the FDA’s evaluation of efficacy significance weighed against the drug’s risks. All we can say is that the breast cancer uptake of Avastin was nowhere near the initial expectations of Financial Analysts, and the continued decline will also be much smaller after the approval’s withdrawal. The majority of the market impact on Avastin occurred immediately after the advisory panel vote. Further declines will be less significant and there will also be some continued use, albeit a fraction of what we saw in early 2010, of Avastin in breast cancer.
The FDA’s move makes it clear that the panel is thinking very much like doctors, seeking the greater survival benefit of drugs tailored to specialized patient populations. In the breast cancer space, this means that blanket approval for a costly drug for all HER2-negative patients is simply too large a market. Clinical trials will increasingly need to test for biomarkers, across all cancer markets.The FDA will likely only become stricter in its reviews.