Updated with additional information. SAN DIEGO ( TheStreet) -- YM Biosciences ( YMI) appears to have a real myelofibrosis drug on its hands. Highly anticipated results from a mid-stage and multi-center study of YM Bio's myelofibrosis drug CYT387 were released Monday night showing the ballyhooed (and controversial) anemia response maintained. Of the 68 myelofibrosis patients who were transfusion dependent when the study started, 46% became transfusion independent for a minimum of 12 weeks and maintained hemoglobin levels equal to or above 8 g/dl. Of the 26 transfusion-dependent patients treated with the 300 mg dose of '387, 62% became transfusion independent and maintained hemoglobin levels equal to or above 8 g/dl. These '387 anemia response data are stronger and more credible than what was presented last spring because Monday's results are culled from many more patients enrolled at multiple clinical trial sites. If '387 can reverse the anemia associated with myelofibrosis, it will have a legitimate superiority claim over Incyte's ( INCY) recently approved myelofibrosis drug Jakafi, which has no effect on anemia. Based on the positive anemia response data released Monday, the current valuation gap between Incyte ($1.8 billion market cap) and YM Bio ($170 million market cap) is way too big even considering '387 is two or three years behind in clinical development. "It's a drug," said Crespi Monness Hardt analyst (and YM Bio supporter) Avik Roy, referring to '387. YM Bio shares closed Monday at $1.46 but were up 24% to $1.81 in after-hours trading as the '387 data were released at the American Society of Hematology (ASH) annual meeting. Myelofibrosisis is a disorder in which abnormal bone marrow stem cells produce scar tissue that replaces healthy marrow. Patients with myelofibrosis suffer from anemia and enlarged spleens. YM Bio's '387 and Incyte's Jakafi belong to a class of oral drugs that block the effects of Janus kinase (JAK) enzymes which play a role in diseases that cause bone marrow cells to grow uncontrollably. The YM Bio phase I/II study enrolled 166 myelofibrosis patients across six study sites, treating them with 150 mg or 300 mg of '387 daily. Of the 142 patients evaluable, 31% achieved a spleen response with a median duration of response not yet reached. Forty-nine percent of patients achieved more than a 50% maximal decrease in spleen size from baseline. Measured by magnetic resonance imaging, the '387 spleen response rate was 64%, which is defined as a 35% drop in spleen volume. Twenty percent of patients experienced mild peripheral neuropathy, while 33% of patients reported thrombocytopenia, or low platelet counts, with 6% grade 4. Twelve patients, or 7%, died during the core portion of the study. --Written by Adam Feuerstein in Boston. >To contact the writer of this article, click here: Adam Feuerstein. >To follow the writer on Twitter, go to http://twitter.com/adamfeuerstein. >To submit a news tip, send an email to: email@example.com. Follow TheStreet on Twitter and become a fan on Facebook.