This abstract is embargoed until the conclusion of the press conference, 
which starts at 9:00 a.m. (EDT) on Monday, May 20.

PLENARY PRESENTATION Lead Author: 
MONDAY, MAY 20, 1:20 p.m. (EDT) 
LEVEL 2, HALL A1-A2  Brian Druker, MD
Oregon Health & Science University
Portland, OR  

STI-571 Effective Against Newly Diagnosed Chronic Myeloid Leukemia

After showing promise against chronic myeloid leukemia in its advanced stages, a
study now demonstrates that the new cancer drug STI-571 (Gleevec) is more effective
and better tolerated than the standard therapy for patients newly diagnosed with
the disease. 

Patients who received STI-571 were more likely to have a complete or partial
remission of their leukemia, compared to those who received the standard therapy
– interferon plus cytarabine, the researchers found.

"Although the long-term results of STI-571 remain unknown, it should now be
considered as standard therapy for newly diagnosed CML patients," said Brian
Druker, MD, of the Oregon Health & Science University, on behalf of the
International Gleevec Study Group. 

The phase III study involved 1,106 patients from 16 countries. Patients were
randomly assigned to receive STI-571 or the interferon-based therapy. STI-571, a
targeted cancer therapy, is already approved for the treatment of CML patients who
no longer respond to interferon and for patients in an accelerated phase or in
myeloid blast crisis. Both are critical stages of CML that are virtually impossible
to treat with standard therapy. Last year, STI-571 also showed dramatic effect
against gastrointestinal stromal tumors (GISTs). 

The current study is the first large-scale clinical trial to evaluate STI-571’s
effectiveness in patients newly diagnosed with the disease and the first to
directly compare STI-571 to the standard therapy. The researchers found that six
months after therapy, leukemia continued to worsen in 8 patients taking STI-571,
versus 57 patients taking the interferon-based therapy. In addition, 75% of
patients taking STI-571 had a significant decrease in the number of cancer cells in
their bone marrow, and within this group, cancer cells had completely disappeared
in 54%. For patients given the standard therapy, 15% had a significant reduction in
the number of cancer cells, and only 3% of those patients experienced a complete
disappearance of cancer cells. 

Only 6 patients treated with STI-571 were in blast crisis six months after therapy,
versus 26 patients who received the interferon-based therapy. In addition, fewer
than 1% of patients given STI-571 experienced severe side effects; 19% of patients
treated with interferon could not tolerate the therapy and were switched to
STI-571.

[Above summary reflects new data]



*1
 
STI571 (Gleevec™/Glivec®, imatinib) versus Interferon (IFN) + cytarabine as
initial therapy for patients with CML: results of a randomized study. 
The IRIS (International Randomized IFN vs. STI571) study group (presented by Brian
Druker, Oregon Health & Science University, Portland, OR) 

Background: STI571, a specific inhibitor of the Bcr-Abl tyrosine kinase, is
effective in late chronic, accelerated, and blast phases of CML. Its activity in
newly diagnosed CML patients has yet to be determined. Following a second planned
interim analysis of this study, the Independent Data Monitoring Board recommended
that the data be disclosed early. Methods: This is an open-label, multi-center,
randomized study of STI571 at 400 mg/d vs. IFN (target dose 5 MIU/m2/day) +
cytarabine (20 mg/m2/day for 10 days/month). The primary endpoint is time to
progression (TTP) defined as either death, progression to accelerated or blast
phase, rapidly increasing WBC, or loss of either a complete hematologic (CHR) or
major cytogenetic response (MCR). Crossover is allowed for loss of CHR or MCR, a
rapidly increasing WBC or severe intolerance of therapy. Results: From June 2000 to
January 2001, 1106 patients were randomized (553 to each arm). Baseline
characteristics were well balanced for age, WBC, Sokal score, and time from
diagnosis. Median duration of first-line therapy was 6.5 and 8.3 months on STI571
and IFN, respectively. At 6 months, the rates of MCR and complete cytogenetic
response were 63% and 40% (STI571) vs. 10% and 2% (IFN)(p<0.001). The STI571 arm
had a significantly better outcome for TTP (8 [1.4%] vs. 57 [10.3%] events) and
time to accelerated phase/blast crisis (6 [1.1%] vs. 26 [4.7%] events) (p<0.001 for
both comparisons, logrank). Crossovers due to intolerance occurred in <1% of STI571
and 19% of IFN-treated patients. Conclusions: These data indicate that STI571 has
significantly greater efficacy and is better tolerated than IFN as first line
treatment of CML. Updated results will be presented at the meeting.