Isis Pharmaceuticals Earns $3.5 Million from Biogen Idec

           Isis Pharmaceuticals Earns $3.5 Million from Biogen Idec

PR Newswire

CARLSBAD, Calif., May 9, 2013

CARLSBAD, Calif., May 9, 2013 /PRNewswire/ -- Isis Pharmaceuticals, Inc.
(NASDAQ: ISIS) announced today that is has earned a $3.5 million milestone
payment from Biogen Idec associated with the dosing of the first patient in a
Phase 2 study of ISIS-SMN[Rx] in infants with spinal muscular atrophy (SMA).

The Phase 2 study of ISIS-SMN[Rx] is an open-label, multiple-dose,
dose-escalation pilot study, which will include eight infants who have been
diagnosed with SMA. To meet enrollment criteria, infants must be between the
ages of three weeks and seven months, live in close proximity to a study site
and pass screening evaluations conducted at study sites. The study will be
conducted at centers in the United States and Canada. For further study
information, please visit www.clinicaltrials.gov and search for the identifier
number NCT01839656.

ABOUT ISIS-SMN[Rx
]ISIS-SMN[Rx] is designed to alter the splicing of a closely related gene
(SMN2) to increase production of fully functional SMN protein. The United
States Food and Drug Administration granted orphan drug status and fast track
designation to ISIS-SMN[Rx] for the treatment of patients with SMA. Isis is
currently in collaboration with Biogen Idec to develop and potentially
commercialize the investigational compound, ISIS-SMN[Rx], to treat all types
of SMA. Under the terms of the January 2012 agreement, Isis is responsible
for global development and Biogen Idec has the option to license the compound
until completion of the first successful Phase 2/3 study. ISIS-SMN[Rx] is
currently being evaluated in a Phase 1b/2a multiple-dose, dose-escalation
study in children with SMA. In this study, children will either receive two
or three doses of ISIS-SMN[Rx] over the course of the study.

Isis acknowledges support from the following organizations for ISIS-SMN[Rx]:
Muscular Dystrophy Association, SMA Foundation, Families of SMA and
intellectual property licensed from Cold Spring Harbor Laboratory and the
University of Massachusetts Medical School.

ABOUT ISIS PHARMACEUTICALS, INC.
Isis is exploiting its leadership position in antisense technology to discover
and develop novel drugs for its product pipeline and for its partners. Isis'
broad pipeline consists of 28 drugs to treat a wide variety of diseases with
an emphasis on cardiovascular, metabolic, severe and rare diseases, and
cancer. Isis' partner, Genzyme, is commercializing Isis' lead product,
KYNAMRO™, in the United States for the treatment of patients with HoFH.
Genzyme is also pursuing marketing approval of KYNAMRO in other markets.
Isis' patents provide strong and extensive protection for its drugs and
technology. Additional information about Isis is available at
www.isispharm.com.

ISIS PHARMACEUTICALS' FORWARD-LOOKING STATEMENT
This press release includes forward-looking statements regarding Isis'
strategic alliance with Biogen Idec, and the discovery, development, activity,
therapeutic and commercial potential and safety of ISIS-SMN[Rx]. Any
statement describing Isis' goals, expectations, financial or other
projections, intentions or beliefs, including the commercial potential of
KYNAMRO, 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 drugs.
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, 2012 and its most recent quarterly report on Form
10-Q, which are on file with the SEC. Copies of these 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.

Isis Pharmaceuticals® is a registered trademark of Isis Pharmaceuticals, Inc.
KYNAMRO™ is a trademark of Genzyme Corporation.

SOURCE Isis Pharmaceuticals, Inc.

Contact: D. Wade Walke, Ph.D., Executive Director, Corporate Communications
and Investor Relations, 760-603-2741; Amy Blackley, Ph.D., Associate Director,
Corporate Communications, 760-603-2772