Isis and Partners Present New Research at the American Association for Cancer Research...

Isis and Partners Present New Research at the American Association for Cancer
Research 2009 Annual Meeting

DENVER and CARLSBAD, Calif., April 20 /PRNewswire-FirstCall/ -- Isis
Pharmaceuticals, Inc. (Nasdaq: ISIS) announced today that Isis and its
collaborators presented results on antisense inhibition of novel targets that
could offer new mechanisms to treat cancer during the American Association for
Cancer Research (AACR) meeting. Research conducted by Isis and its
collaborators demonstrated the feasibility of targeting a large non-coding
RNA, sigma RNA also known as Malat-1, that could offer a new therapeutic
mechanism to treat disease. Isis also presented new preclinical data showing
that antisense inhibition of STAT5 resulted in potent anti-tumor activity.
The oral presentations were presented today, April 20, at the AACR 100th
Annual Meeting 2009 in Denver, Colorado by Isis and its collaborators.

The presentation by R. Lin from The Scripps Research Institute on work done in
collaboration with scientists from Isis and titled "Molecular Control of RNA
Alternative Splicing by sigma RNA, a Marker for Carcinomas" showed that
antisense inhibition of Malat-1 altered the splicing of multiple mRNAs.
Altering splicing results in the production of different variations of a
protein, including variations that could be associated with cancer. Malat-1
is up-regulated in many human cancers including liver, breast, lung, pancreas,
colon, and prostate.

Isis scientist Y. Kim presented research titled "Selective Inhibition of STAT5
Expression in Acute Myeloid Leukemia Cells Results in Potent Antitumor
Activity" showing that antisense inhibition of STAT5 increased survival in
preclinical models of acute myeloid leukemia (AML) suggesting that antisense
drugs targeting STAT5 may offer a new avenue to treat AML and related blood
disorders.

"The work presented at this year's AACR demonstrates the broad applicability
of antisense technology and adds to our previously published work using
antisense to target different classes of RNAs, including microRNAs and other
non-coding RNAs. We and our collaborators have shown that antisense
inhibition of non-coding RNAs can impact splicing patterns in cells to
modulate the expression of multiple proteins that may be involved in disease,"
said C. Frank Bennett, Ph.D., Senior Vice President of Research at Isis
Pharmaceuticals. "Furthermore, the work of our team on STAT5 provides yet
another oncology target with the potential for anti-tumor activity. We
believe that antisense drugs have pharmaceutical properties that make them
attractive therapeutics for cancer, and we are expanding our efforts in cancer
to include new targets and new approaches."

ABOUT ISIS PHARMACEUTICALS, INC.
Isis is exploiting its expertise in RNA to discover and develop novel drugs
for its product pipeline and for its partners. The Company has successfully
commercialized the world's first antisense drug and has 19 drugs in
development. Isis' drug development programs are focused on treating
cardiovascular and metabolic diseases. Isis' partners are developing
antisense drugs invented by Isis to treat a wide variety of diseases. Isis
and Alnylam Pharmaceuticals are joint owners of Regulus Therapeutics Inc., a
company focused on the discovery, development and commercialization of
microRNA therapeutics. Isis also has made significant innovations beyond
human therapeutics resulting in products that other companies, including
Abbott, are commercializing. As an innovator in RNA-based drug discovery and
development, Isis is the owner or exclusive licensee of over 1,600 issued
patents worldwide. Additional information about Isis is available at
www.isispharm.com.

This press release includes forward-looking statements regarding Isis'
business, its drug discovery and development pipeline, and the therapeutic
potential of antisense drugs for the treatment of cancer. Any statement
describing Isis' goals, expectations, financial or other projections,
intentions or beliefs is a forward-looking statement and should be considered
an at-risk statement. Such statements are subject to certain risks and
uncertainties, particularly those inherent in the process of discovering,
developing and commercializing drugs that are safe and effective for use as
human therapeutics, and in the endeavor of building a business around such
products. Isis' forward-looking statements also involve assumptions that, if
they never materialize or prove correct, could cause its results to differ
materially from those expressed or implied by such forward-looking statements.
Although Isis' forward-looking statements reflect the good faith judgment of
its management, these statements are based only on facts and factors currently
known by Isis. As a result, you are cautioned not to rely on these
forward-looking statements. These and other risks concerning Isis' programs
are described in additional detail in Isis' annual report on Form 10-K for the
year ended December 31, 2008, which is on file with the SEC. Copies of this
and other documents are available from the Company.

In this press release, unless the context requires otherwise, "Isis,"
"Company," "we," "our," and "us" refers to Isis Pharmaceuticals and its
subsidiaries, including Regulus Therapeutics Inc.

Isis Pharmaceuticals is a registered trademark of Isis Pharmaceuticals, Inc.
Regulus Therapeutics is a trademark of Regulus Therapeutics Inc.

SOURCE Isis Pharmaceuticals, Inc.

Kristina Lemonidis, Director, Investor Relations, +1-760-603-2490, or Amy
Blackley, Ph.D., Assistant Director, Corporate Communications,
+1-760-603-2772, both of Isis Pharmaceuticals, Inc.