Trubion Announces Positive Data From a Phase 1 / 2 Study of TRU-016 for the Treatment...

Trubion Announces Positive Data From a Phase 1 / 2 Study of TRU-016 for the
Treatment of Chronic Lymphocytic Leukemia (CLL)

SEATTLE and ORLANDO, Fla., June 1 /PRNewswire-FirstCall/ -- Trubion
Pharmaceuticals, Inc. (Nasdaq: TRBN) announced today the presentation of
encouraging Phase 1 safety and efficacy results following administration of
low doses of TRU-016 in heavily pre-treated patients with high-risk genomic
factors and relapsed or refractory chronic lymphocytic leukemia (CLL). TRU-016
is the Company's proprietary anti-CD37 Small Modular ImmunoPharmaceutical
(SMIP(TM)) product candidate.

(Logo: http://www.newscom.com/cgi-bin/prnh/20090320/TRUBIONLOGO)

Abstract 3017: A Phase 1 Trial of TRU-016, An Anti-CD37 Small Modular
ImmunoPharmaceutical (SMIP(TM)), in Relapsed and Refractory CLL -- Early
Promising Clinical Activity
The clinical data presented at the American Society of Clinical Oncology
(ASCO) are preliminary results from an ongoing Phase 1 / 2 clinical trial
(#16007) of TRU-016 for the treatment of CLL and small lymphocytic leukemia
(SLL). The objectives of the Phase 1 TRU-016 CLL study were to define safety
and tolerability, identify a maximum tolerated dose, evaluate pharmacology and
pharmacodynamics, and assess preliminary clinical activity. Patients received
either one dose weekly for four weeks, or three doses the first week followed
by three additional weekly doses. Patients were also able to receive up to two
additional cycles if clinical benefit was observed.

At the time of the presentation, data were available for 26 patients enrolled
in the Phase 1 dose escalation trial, all of whom had received an average of
6.5 prior treatments, including at least one fludarabine-containing regimen.
All patients had also previously received rituximab or other anti-CD20
therapies an average of three times, either as a single agent or as part of a
combination regimen. Of the 24 patients with genetic data, 17 had high genomic
risk factors, such as deletion of the 17p or 11q chromosomes. At the time of
the presentation, patients had received intravenous doses of TRU-016 ranging
from 0.03 mg/kg to 10 mg/kg over the course of four to 12 weeks.

Beginning with the 0.1 mg/kg dose, evidence of biologic activity was observed.
The median reduction in peripheral lymphocytes was 67% and was as high as 98%.
Two patients with leukemia cutis had complete or partial clearance of skin
lesions. One patient had a 36% reduction in lymph node size, a 28% decrease in
spleen size and a significant increase (44%) in hemoglobin. Mild grade 1 or 2
infusion toxicity was observed and there were three dose-limiting toxicities
reported that all occurred in different dose cohorts. A maximum tolerated dose
has not yet been reached.

Also presented at the ASCO Annual Meeting this week was data demonstrating
that TRU-016 is additive or synergistic in combination with established
therapeutics (Abstract 8571) and that TRU-016-mediated apoptosis in CLL cells
occurs via a distinct mechanism of apoptosis compared with many other
therapeutic agents utilized for the treatment of CLL (Abstract 3035). Copies
of all three presentations are available on Trubion's website at
http://investors.trubion.com/events.cfm.

"These results show promising single agent activity of TRU-016, even at
surprisingly low doses, in a heavily pre-treated patient population most of
whom harbored genetic lesions known to be associated with poor response to
standard therapies," said Peter Thompson, M.D., FACP, president, CEO and
chairman of Trubion. "These data suggest that this novel, first-in-class
compound may become a new treatment option for patients with B-cell
malignancies, either as a stand-alone treatment or when used in combination
with other therapies. These diseases are not curable presently, and eventually
patients with these diseases show diminished response to current therapies.
These patients and their physicians need more effective therapies with new
mechanisms of action that address new targets. We look forward to presenting
additional data on our expanding clinical experience with TRU-016 as it is
accrued."

TRU-016 is a humanized, SMIP protein therapeutic that targets the CD37 antigen
and has shown potent anti-tumor activity in pre-clinical studies. Trubion
initiated a Phase 1 / 2 clinical trial of TRU-016 in March 2008. The
open-label clinical trial has two components: a Phase 1 dose escalation study
designed to evaluate the safety, tolerability and pharmacokinetics of TRU-016,
and a Phase 2 expansion cohort designed to further evaluate safety and
estimate clinical activity of TRU-016 in patients with previously treated CLL
or SLL.

About Trubion
Trubion is a biopharmaceutical company that is creating a pipeline of novel
protein therapeutic product candidates to treat autoimmune and inflammatory
diseases and cancer. The Company's mission is to develop a variety of
first-in-class and best-in-class product candidates, customized for optimal
safety, efficacy and convenience that it believes may offer improved patient
experiences. Trubion's current product candidates are novel single-chain
protein, or SMIP(TM), therapeutics, and are designed using its custom drug
assembly technology. Trubion's product pipeline includes CD20-directed SMIP
therapeutics such as TRU-015 and SBI-087 for autoimmune and inflammatory
diseases, developed under the Company's Wyeth collaboration. Trubion's product
pipeline also includes Trubion's proprietary product candidate, TRU-016, a
novel CD37-targeted therapy for the treatment of B-cell malignancies that is
currently in Phase
1 / 2 clinical evaluation. In addition to Trubion's current clinical stage
product pipeline, the Company is also developing additional product candidates
that build on its product development experience. More information is
available in the investors section of Trubion's website:
http://investors.trubion.com/index.cfm.

Forward-Looking Statements
Certain statements in this release may constitute "forward-looking statements"
within the meaning of Section 21E of the Securities Exchange Act of 1934 and
Section 27A of the Securities Act of 1933. These statements include, but are
not limited to, those related to the Company's future clinical development
programs and the timing thereof, the Company's future regulatory filings and
the timing and outcome thereof. These statements are based on current
expectations and assumptions regarding future events and business performance
and involve certain risks and uncertainties that could cause actual results to
differ materially. These risks include, but are not limited to, risks
associated with the clinical advancement of TRU-016, the Company's Wyeth
collaboration, including Wyeth's control over development timelines, the risks
that the Company is unable to advance its clinical development programs and
regulatory applications and action at the rate it expects, and such other
risks as identified in the Company's quarterly report on Form 10-Q for the
period ended March 31, 2009, and from time to time in other reports filed by
Trubion with the U.S. Securities and Exchange Commission. These reports are
available on the Investors page of the company's corporate website at
http://www.trubion.com/. Trubion undertakes no duty to update any
forward-looking statement to conform the statement to actual results or
changes in the Company's expectations.

Contact:
Jim DeNike
Senior Director, Corporate Communications
Trubion Pharmaceuticals, Inc.
(206) 838-0500
jdenike@trubion.com
http://www.trubion.com

Waggener Edstrom Worldwide Healthcare
Amy Petty
Senior Account Executive
(617) 576-5788
amyp@waggeneredstrom.com

TRBN-016CLL

SOURCE Trubion Pharmaceuticals, Inc.

Jim DeNike, Senior Director, Corporate Communications of Trubion
Pharmaceuticals, Inc., +1-206-838-0500, jdenike@trubion.com; or Amy Petty,
Senior Account Executive of Waggener Edstrom Worldwide Healthcare,
+1-617-576-5788, amyp@waggeneredstrom.com, for Trubion Pharmaceuticals, Inc.