ymi vs. Incy from jonathan Aschoff
We primarily wanted to point out some differences between INCB18424 and CYT387, as these drugs are often directly compared. We emphasize that data for CYT387 comes from 60 patients followed for a median of two months and that data for INCB18424 comes from 153 patients followed for a median of 20 months, and thus drawing useful comparisons best wait for more mature data from YM Boisciences, but by which time we will already have Phase 3 data from Incyte. We also wanted to point out that transfusion independence was in fact measured differently in the INCB18424 NEJM paper than it was in the ongoing YM trial, and thus conclusions about CYT387’s superiority in reversing anemia are premature. Later this month, should INCB18424 succeed in Phase 3 with spleen size reductions in the Phase 1/2 ballpark and acceptable safety, it is in our view way too early to consider CYT387 a serious future threat about four years from now. We also discuss Incyte’s updated PV and ET results.
Discussion
§Concerning anemia and transfusion independence, there appears to be a real difference between the definitions that both companies are using to define the transfusion independence. Incyte was trying to use a more inclusive definition of transfusion independence in order to describe patients that are freer of transfusions than the less stringent IWG criteria. Incyte’s definition describes a patient that is transfusion free for 12 consecutive weeks or at least during the last 8 weeks on study (or the last 8 weeks prior to database closure for Incyte’s published NEJM paper), whereas the more standard IWG definition used by YM less stringently requires a patient to go any 8 weeks without a transfusion. The confusion lay in the fact that the NEJM paper describing Incyte’s Phase 1/2 did not accurately describe the actual criteria used. This statement in the paper “After a median treatment duration of 12 weeks, four patients (14%) had transfusion independence (clinical improvement according to the International Working Group) for a median duration of 20 months.” inaccurately describes the criteria used. In fact, the Phase 2 median transfusion free period of 20 months for INCB18424 patients that qualified as being transfusion independent was defined under Incyte’s stricter definition described above.
If a patient in YM’s trial had a transfusion right before enrolling in the trial, and several transfusions more than two months after dosing started, they would have been considered to be transfusion free. Due to the different definitions used for transfusion independence, and what we view to be unfair comparisons drawn by YM, Incyte calculated its data using the more forgiving standard IWG definition used by YM in order to directly and more fairly compare these results. Using this more proper comparison, one can see a comparable anemia response between the two drugs, with INCB18424 showing a 45% response, and CYT387 showing a 50% response. Furthermore, given the numerical similarity between these measurements, that fewer patients (n=60) were reported on from the CYT387 trial than in Incyte''s trial (n=153), and that median follow up was two months for YM versus 20 months for Incyte, we view YM''s findings as far less robust at present and in need of much maturation prior to drawing any definitive comparisons regarding transfusion independence.
