as a potentially safer, and lower-cost, alternative. The Amgen drug is made of fully human DNA copies. That’s different than the part-mouse, part-human antibodies in the Lilly product, which are thought to be capable of sparking more of an immune-system reaction against the drug.
Not surprisingly, the safety concern has made it hard for Amgen to gin up sales for this product, which had $170 million in sales last year. But instead of letting the Amgen drug fade into a treatment of last resort, the company went back to what it learned from tumor samples collected from earlier trials, as I described in this story back in August. When the company filtered patients based on whether they had a normal KRAS gene, or a mutated form, they found a striking result.
About 17 percent of patients with normal KRAS genes had tumors shrink after they took the drug, while none of those with mutated KRAS genes saw that benefit, according to research published in March in the Journal of Clinical Oncology.
Amgen thinks that result may point to a way to salvage the commercial potential of this drug. Patients in the niche may be more motivated to take the drug if they can see it has a higher likelihood of working. Amgen has compared this situation to Genentech’s success with trastuzumab (Herceptin), a drug that’s approved only for about one-fourth of breast cancer patients with a mutated form of the HER2 gene. Even without selling the drug to all breast cancer patients, Genentech was able to generate $1.3 billion in U.S. sales last year.
The FDA has made it clear it wants to encourage more drugmakers to do this kind of precise whittling of patient populations, to boost the likelihood of success. The part officials don’t like is that few companies plan ahead to do this kind of analysis. Rather, they decide to shoot for the largest patient population in clinical trials, and then try to do statistically dubious “data dredging” after a trial is completed to fish around for some positive sign in a subgroup.
“An ideal scenario is one in which the relationship of the biomarker to potential action of
the drug is recognized very early—indeed, such a relationship might be the motivation
for starting the drug’s development,” the FDA said in its briefing document in advance of the panel.
Both Amgen and Lilly say they want to be able to include new data in their drugs’ prescribing information, so they can legally promote the benefits of the drugs for patients with normal KRAS status. If they get their way with the drug label, and time shows that this strategy expands sales rather than limits them, then you might well see other companies starting to get with the program of more personalized medicine.
