Trubion Announces Completion Of Enrollment And Dosing Of Patients In Phase IIb Clinical Trial Of TRU-015 For The Treatment Of Rheumatoid Arthritis

Trubion Pharmaceuticals,
Inc. (Nasdaq: TRBN), today announced it has completed enrollment and dosing
of patients in its Phase IIb clinical trial of TRU-015, the Company's lead
Small Modular ImmunoPharmaceutical (SMIP(TM)) drug candidate for the
treatment of rheumatoid arthritis (RA). The randomized, double-blind,
placebo-controlled clinical trial is designed to evaluate safety and
clinical response rates in patients with rheumatoid arthritis.


"We are pleased with the rapid enrollment of this study and look
forward to reporting its results later this year," said Peter Thompson,
M.D., co-founder, president and CEO of Trubion. "Previously reported
TRU-015 clinical trial data has been promising and we expect that the
results of our ongoing clinical evaluation will serve as the basis for
Phase III pivotal trial design."



TRU-015 Phase IIb Clinical Trial Protocol



The Phase IIb randomized, double-blind, placebo-controlled clinical
trial is designed to enroll 280 patients with rheumatoid arthritis.
Patients have been randomized into five groups to evaluate the safety and
efficacy of an infused dose of TRU-015 compared to placebo for a 24-week
period. Building on the findings of Trubion's Phase IIa clinical trial,
this trial will evaluate the effect of a single infusion of TRU-015 ranging
from 200 mg to 1,600 mg per patient.



Similar to the Phase IIa study, this study will evaluate composite
measurements of improvement in disease activity derived from parameters
such as tender and swollen joint counts, patient and physician global
assessments, patient assessment of pain and disability, and laboratory
measures of inflammation as defined by the American College of
Rheumatology.



About TRU-015 and SMIPs



Trubion and Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE) are
developing TRU-015, a SMIP(TM) drug candidate, as a potential new therapy
for RA. SMIP(TM) drugs represent a novel class of immunotherapeutics that
Trubion believes possess enhanced drug properties over monoclonal and
recombinant antibodies.



In February 2006, the Company completed enrollment in a Phase IIa study
in RA patients designed to demonstrate proof of concept that TRU-015
measurably improves the signs and symptoms of rheumatoid arthritis. In the
first 24 weeks after receiving intravenous infusions of TRU-015, 72 percent
of the subjects experienced a clinical response that is equal to or greater
than that required to achieve an ACR20 response, 28 percent achieved an
ACR50 response and 14 percent achieved an ACR70 response. In these measures
of clinical response, ACR 50 and ACR70 indicate progressively greater
responses from a baseline measure than ACR20, which is defined as an
improvement of at least 20 percent from baseline in counts of both tender
and swollen joints, as well as in at least three of five other disease
activity parameters.
















About Rheumatoid Arthritis



According to Datamonitor, RA is estimated to affect approximately 4.3
million people in the United States, Japan and Europe. In 2005, total
reported worldwide sales of protein therapeutics used for the treatment of
RA were $7.6 billion. Total worldwide sales of protein therapeutics for the
treatment of RA are expected to grow to $10 billion in 2010.



About Trubion



Trubion is a biopharmaceutical company creating a pipeline of product
candidates to treat autoimmune disease and cancer. The Company's product
candidates are novel proteins known as single-chain polypeptides and are
designed using its SMIP(TM) custom drug assembly technology. In less than
24 months, the Company designed, developed and submitted to the FDA an
Investigational New Drug application for its lead product candidate,
TRU-015, which is currently being tested in a Phase IIb clinical trial for
the treatment of rheumatoid arthritis. In December 2005, the Company
entered into a collaboration agreement with Wyeth for the development and
worldwide commercialization of certain therapeutics, including TRU-015. In
addition, Trubion's TRU-016 program targets CD37, an antigen present on B
cells, for the treatment of non-Hodgkin's lymphoma and chronic lymphocytic
leukemia. Subject to satisfactory completion of preclinical testing of
TRU-016, the Company expects to file an IND for TRU-016 in the second half
of 2007. Trubion currently retains all development and commercialization
rights for the TRU-016 program. For additional information visit
trubion/.



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, future clinical
development plans, the details of the clinical trials and the results and
timing thereof, the timing of regulatory applications and action. These
statements are based on current expectations and assumptions regarding
future events and the expected future size of the market for protein
therapeutics for the treatment of RA, 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 ability of the company to successfully conduct clinical trials for
TRU-015 and other SMIP(TM) candidates, the uncertainty of the FDA approval
process and other regulatory requirements, the therapeutic and commercial
value of Trubion's drug candidates, the company's collaboration
relationship with Wyeth, including its ability to receive milestone
payments from Wyeth, and risks associated with defending and enforcing any
patent claims and other intellectual property rights; and such other risks
as identified in the company's quarterly report on Form 10-Q for the period
ended September 30, 2006 and from time to time in other reports filed by
Trubion with the U.S. Securities Exchange Commission. These reports are
available on the Investors page of the company's corporate Web site at
trubion. Trubion undertakes no duty to update any forward-looking
statement to conform the statement to actual results or changes in the
company's expectations.


Trubion Pharmaceuticals, Inc.

trubion/