You may be right, but as long as people are living dramatically longer once they start on Kadcyla, it's market should grow substantially each year. I say this because in the refractory market, I believe treatment will continue indefinitely with Kadcyla.
Some time ago a expressed the opinion that Gleevec was a great drug for the drugmaker as it was effective essentially as long as patients took it. Patients exhibited being disease free, but only as long as they took the disease. I'm currently on the third generation of Gleevec, it's called Sprycel, and my Dr. believes I should take it for the remainder of my life. I see Kadcyla being somewhat the same. I don't know the numbers, but let's say each year 10K patients start on Kadcyla, and if the majority remain on it, the total numbers would grow substantially each year.
I believe it's also becoming clear that for many the quality of life issues with Kadcyla in combination is better than Herceptin even if the outcome isn't dramatically different. If I'm correct about this, I believe that physicians will move in this direction even if it's considered off label use. I can't say how rapidly such use will grow, but my experience in treatment for Leukemia tells me that the Doctor's have little problem in using the drug that they select. Perhaps my experience is slanted because City of Hope has that sort of credibility, but I really believe that Doctors can use approved drugs as they wish. As Doctor's experience with Kadcyla grows, I believe they'll use it more.
Gary