Rigel Provides Pipeline Update

                        Rigel Provides Pipeline Update

Path Forward Clear for Fostamatinib, Ends for R333

PR Newswire

SOUTH SAN FRANCISCO, Calif., Oct. 24, 2013

SOUTH SAN FRANCISCO, Calif., Oct. 24, 2013 /PRNewswire/ -- Rigel
Pharmaceuticals, Inc. (Nasdaq: RIGL) today announced updates on two of the
Company's pipeline products: R333, a topical dermatological JAK/SYK inhibitor,
and fostamatinib, an oral SYK inhibitor.

R333 Update
Rigel announced that R333, which was being evaluated as a potential
therapeutic for active skin lesions in patients with discoid lupus
erythematosus (DLE), did not meet the primary endpoint in a recently completed
Phase 2 clinical study. The primary endpoint was the proportion of patients
who achieved at least a 50% decrease from baseline in the total combined
Erythema and Scaling score of all treated lesions at Week 4. R333 was shown
to be relatively safe and well tolerated. In light of these overall findings,
Rigel has decided not to pursue this indication further with R333.

Fostamatinib Update
Rigel representatives met with the FDA for an end-of-Phase 2 meeting for
fostamatinib, an oral SYK inhibitor in development for patients with immune
thrombocytopenic purpura (ITP). Rigel expects to initiate two pivotal Phase 3
studies in the first half of 2014. Each of these trials are expected to
enroll approximately 75 patients who would be treated for six months and have
the option to enroll in an extension study. These trials will be randomized,
placebo-controlled and will enroll verified ITP patients with platelet counts
below 30,000 platelets per microliter of blood. The goal of the trials will
be to achieve a durable platelet count increase to over 50,000 platelets per
microliter of blood. Rigel expects top line data from these studies in 2015.

"These events provide clarity to Rigel's pipeline. We now have a clear picture
of the Phase 3 program for fostamatinib in ITP and we plan to start the
studies early next year," said James M. Gower, chairman and chief executive
officer of Rigel. He also said, "Unfortunately, discoid lupus is a difficult
indication and R333 didn't provide the benefit we had hoped. However, this
frees up resources to focus on our ITP and dry eye programs."

About Rigel (www.rigel.com)
Rigel Pharmaceuticals, Inc.is a clinical-stage drug development company that
discovers and develops novel, small-molecule drugs for the treatment of
inflammatory and autoimmune diseases, as well as muscle disorders. Rigel's
pioneering research focuses on intracellular signaling pathways and related
targets that are critical to disease mechanisms. The company currently has
five product candidates in development: fostamatinib, an oral SYK inhibitor
for ITP that is expected to commence Phase 3 clinical trials in the first half
of 2014; R348, a topical JAK/SYK inhibitor for dry eye in Phase 2 clinical
trials; R118, an AMPK activator entering Phase 1 in early 2014; and two
oncology product candidates in Phase 1 development with partners BerGenBio AS
andDaiichi Sankyo.

This press release contains "forward-looking" statements, including, without
limitation, statements related to development plans and results, including
development plans and timing for fostamatinib for ITP. Any statements
contained in this press release that are not statements of historical fact may
be deemed to be forward-looking statements. Words such as "planned," "will,"
"may," "expect," and similar expressions are intended to identify these
forward-looking statements. These forward-looking statements are based on
Rigel's current expectations and inherently involve significant risks and
uncertainties. Actual results and the timing of events could differ materially
from those anticipated in such forward looking statements as a result of these
risks and uncertainties, which include, without limitation, the availability
of resources to develop Rigel's product candidates, our need for additional
capital in the future to sufficiently fund our operations and research, the
uncertain timing of completion of and the success of clinical trials, market
competition, risks associated with and Rigel's dependence on Rigel's corporate
partnerships, as well as other risks detailed from time to time in Rigel's
reports filed with theSecurities and Exchange Commission, including its
Quarterly Report on Form10-Q for thequarter ended June 30, 2013. Rigel does
not undertake any obligation to update forward-looking statements and
expressly disclaims any obligation or undertaking to release publicly any
updates or revisions to any forward-looking statements contained herein.

Contact: Raul Rodriguez
Phone: 650.624.1302
Email: invrel@rigel.com

Media Contact: Susan C. Rogers, Alchemy Consulting, Inc.
Phone: 650.430.3777
Email: susan@alchemyemail.com

SOURCE Rigel Pharmaceuticals, Inc.

Website: http://www.rigel.com