BOSTON ( TheStreet) -- @Eli75NY tweets, "Adam, are you still big on $YMI? In the past you named it top 10 Bio under $300 million cap? Thanks."

YM Biosciences ( YMI) faces a big test Monday night when new data on its myelofibrosis drug CYT387 is presented at the American Society of Hematology (ASH) annual meeting.

These new CYT387 results will encompass data from 166 myelofibrosis patients enrolled at six centers, giving YM Bio an opportunity to counter the skepticism raised by non-believers when initial study results culled from about 60 patients at the Mayo Clinic were presented last spring.

Or, the new CYT387 data will prove the YM Bio bears correct.

The key watch points for Monday's 6 p.m. New York time presentation:

1. Will the anemia response hold up? CYT387's ticket to stardom is its potential to reverse the anemia associated with myelofibrosis. This is important because myelofibrosis patients who are anemic or require red blood cell transfusions have more aggressive disease and shorter life spans. If CYT387 can demonstrate a positive and clinically meaningful impact on anemia in myelofibrosis patients, it could claim superiority over Incyte's ( INCY) recently approved drug Jakafi, which has no effect on anemia.

From the last data presentation in June (42 evaluable CYT387 patients), 50% achieved an anemia response. All anemia responses persisted for a minimum of 12 weeks. Of the 33 patients transfusion dependent at baseline, 19, or 58%, became transfusion independent, with a median duration of transfusion independence of 7.5 months.

These data came from patients all treated at the Mayo Clinic, which led to questions about selectivity bias. The data to be presented Monday will come from multiple centers and will incorporate many more patients.

An equal or better anemia response rate Monday will be very positive. More likely the anemia response decreases. How much lower is acceptable to investors is hard to gauge. Monness Crespi Hardt analyst Avik Roy says he's keying on the patient's hemoglobin curves, which should go up over time on CYT387 treatment if the drug's anemia response is real.

"Those same curves go down for Jakafi," he says. "Even if the anemia response is lower this time around, it still puts CYT387 far ahead of Incyte's drug."

Whatever the anemia data show, expect Incyte bulls to stubbornly question the impact. Front and center will likely be Bank of America analyst Rachel McMinn, a big Incyte bull and a vocal YM Bio bear.

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