From the Wires
YM BioSciences Reports Phase I/II Data for JAK Inhibitor CYT387 in Myelofibrosis at ASH 2012
Dec. 9, 2012 05:15 PM
- 68% transfusion independence response rate and 37% durable spleen
response rate -
MISSISSAUGA, ON, Dec. 9, 2012 /PRNewswire/ - YM BioSciences Inc. (NYSE MKT: YMI, TSX: YM) today reported updated results from the 166 patient Phase I/II study of
its JAK1/JAK2 inhibitor, CYT387, for the treatment of myelofibrosis.
The results were presented this afternoon in an oral session at the 54th Annual Meeting of the American Society of Hematology underway in
68% durable 12-week transfusion independence response rate with a
maximal duration of response approaching three years and ongoing.
The percentage of patients requiring transfusions decreased
substantially, from 44% at baseline to below 10% at week 40 of
37% durable spleen response per IWG-MRT* with a maximal duration of
response of nearly 2.5 years and ongoing.
The majority of subjects achieved a complete resolution or marked
improvement of common constitutional symptoms.
The majority of adverse events were Grade 1.
"These data continue to demonstrate that treatment with CYT387 results
in significant, durable responses in transfusion dependency,
splenomegaly and constitutional symptoms," said Dr. Nick Glover,
President and CEO of YM BioSciences. "The benefits CYT387 produces are
highly encouraging for patients with myelofibrosis and underscore the
clinical potential of this drug."
*International Working Group for Myelofibrosis Research and Treatment
Phase I/II Core Study Results
Study Design and Subject Disposition
The Core Study consisted of nine 28-day treatment cycles where CYT387
was orally self-administered, primarily at dosages of 150 mg once-daily
(QD), 300 mg QD or 150 mg twice-daily (BID). Patients who tolerated and
benefited from the drug could continue to receive CYT387 for an
indefinite period beyond the Core Study in an Extension Study. The 300
mg QD dosing regimen has been selected for use in the anticipated Phase
III clinical development program.
The median follow-up time for patients in the Core Study and Extension
Study is 16.9 months (range: 0.8 - 34.2 months; ongoing). During the
Core Study, 42 patients (25%) discontinued the study, eight for
possibly or probably related adverse events, for an overall retention
rate of 75%.
Subject Baseline Characteristics
The majority of the 166 patients enrolled across the six study sites
have primary myelofibrosis (63%); 22% have post-polycythemia vera
myelofibrosis and 15% have post-essential thrombocythemia
myelofibrosis. Other patient characteristics include:
DIPSS-Plus category: Int-1 - 10%; Int-2 - 62%; High - 28%
RBC (Red blood cell) transfusion-dependent: 44%
Palpable splenomegaly >10 cm: 79%
Patients who had received previous therapies, including other JAK
inhibitors (13%) and IMiDs (9%).
Transfusion Independence Response
Of the 68 evaluable patients who were transfusion dependent at baseline,
68% became transfusion independent for a minimum of 12 weeks during the
Core Study. The median duration of the transfusion-free period has not
yet been reached (range: 85 - 988 days, ongoing). Of the transfusion
dependent patients who did not achieve a full transfusion independence
response, 23% achieved at least a 50% reduction in transfusion
requirement in any 3-month period.
The percentage of patients requiring transfusions decreased
substantially during the study, from 44% at baseline to below 10% at
week 40 of treatment.
Of the 28 evaluable patients who were transfusion dependent at baseline
and dosed at 300 mg QD, 75% have become transfusion independent for a
minimum of 12 weeks.
Three additional patients achieved a 12-week transfusion independence
response during the Extension Study.
Of the 145 patients evaluable for spleen response by palpation, 37%
achieved a response per IWG-MRT. The median duration of spleen response
reported was 744 days (range: 56 - 859 days, ongoing). Three additional
subjects achieved spleen response during the Extension Study.
During the Core Study, 50% of evaluable patients achieved more than a
50% maximal decrease in spleen size from baseline, with 87% achieving
more than a 25% maximal decrease.
Of the 51 patients who were evaluable for spleen response and dosed at
300 mg QD, 39% achieved a response per IWG-MRT.
In the Core Study, 11 patients were evaluable for spleen response by
MRI. The response rate at six months was 45% by MRI (defined as a 35%
decrease in spleen volume) and the median splenic decrease from
baseline at six months was -41% by volume measured by MRI.
Constitutional Symptoms Response
The majority of patients reporting constitutional symptoms at baseline
demonstrated a Complete Resolution or Marked Improvement of their
symptoms, including night sweats, pruritus and bone pain.
CYT387 is well tolerated in myelofibrosis patients for dosing periods
currently up to three years and ongoing. The majority of adverse events
were Grade 1. Common reported adverse effects include thrombocytopenia;
transient, mild dizziness; mild peripheral neuropathy; and
abnormalities in liver/pancreas-related laboratory tests.
Treatment-emergent anemia and neutropenia were rarely observed.
Oral presentation and YM conference call:
The results from the Phase I/II study are being presented today at
5:15pm ET in an Oral Session at the 2012 Annual Meeting of the American
Society of Hematology in Atlanta, Georgia. YM will also host a webcast
meeting open to members of the investment community to discuss the
results. This event will be held from 6:30-7:30am ET on Monday,
December 10th in the Imperial Salon Room A of the Atlanta Marriott Marquis, 265
Peachtree Center Ave. NE, Atlanta, Georgia. Access to the webcast will
be available from YM's website at www.ymbiosciences.com or at www.newswire.ca.
CYT387 is an inhibitor of the kinase enzymes JAK1 and JAK2, which have
been implicated in a family of hematological conditions known as
myeloproliferative neoplasms, including myelofibrosis, and as well in
numerous other disorders including indications in hematology, oncology
and inflammatory diseases. Myelofibrosis is a chronic debilitating
disease in which a patient's bone marrow is replaced by scar tissue and
for which treatment options are limited or unsatisfactory. Both the
U.S. Food and Drug Administration (FDA) and the European Commission
have designated CYT387 an Orphan Drug for the treatment of
About YM BioSciences
YM BioSciences Inc. is a drug development company primarily focused on
advancing CYT387, an orally administered inhibitor of both the JAK1 and
JAK2 kinases, which have been implicated in a number of hematological
and immune cell disorders including myeloproliferative neoplasms and
inflammatory diseases as well as certain cancers. Positive interim
results have been reported from a Phase I/II trial of CYT387 in 166
patients with myelofibrosis. YM's portfolio also includes several
preclinical programs underway with candidates from its library of novel
compounds identified through internal research conducted at YM
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SOURCE YM BioSciences Inc.