Gilead to Stop Phase 3 Study 116 of Idelalisib in Chronic Lymphocytic Leukemia Early Because of Positive Risk-Benefit

  Gilead to Stop Phase 3 Study 116 of Idelalisib in Chronic Lymphocytic
  Leukemia Early Because of Positive Risk-Benefit

Business Wire

FOSTER CITY, Calif. -- October 9, 2013

Following a recommendation by an independent Data Monitoring Committee (DMC),
Gilead Sciences, Inc.(Nasdaq:GILD) today announced that its Phase 3 study
(Study 116) evaluating idelalisib in previously-treated chronic lymphocytic
leukemia (CLL) patients who are not fit for chemotherapy will be stopped
early. This DMC recommendation is based on a predefined interim analysis
showing highly statistically significant efficacy for the primary endpoint of
progression-free survival in patients receiving idelalisib plus rituximab
compared to those receiving rituximab alone. The safety profile of idelalisib
was acceptable and consistent with prior experience in combination with
rituximab in previously treated CLL. Gilead has informed the U.S. Food and
Drug Administration (FDA) of the plan to end the study and will engage in a
dialogue with the FDA regarding a regulatory filing in CLL. Data from Study
116 will be submitted for presentation at an upcoming scientific conference.

“Given the significant unmet medical need in CLL, particularly in this
population of patients who are not fit for chemotherapy, we are pleased that
idelalisib has shown a clinically meaningful benefit for patients,” said
Norbert W. Bischofberger, PhD, Gilead’s Executive Vice President, Research and
Development and Chief Scientific Officer. “This is the first Phase 3 study to
report positive results for a new class of targeted therapies that inhibit
B-cell receptor signaling as a major component of their mechanism of action,
an important area of focus in the development of chemotherapy-free regimens in
CLL and other B-cell malignancies. We extend thanks to the investigative sites
and to the other research collaborators participating in this study, as well
as to the patients who volunteered, and we look forward to sharing these data
with the hematology community.”

Patients from Study 116 randomized to idelalisib will continue receiving
idelalisib and patients in the control arm (placebo plus rituximab) will
become eligible to receive open-label idelalisib therapy in an extension
study. Gilead is also planning an expanded access program (EAP) for patients
with recurrent CLL who are not fit for chemotherapy and require treatment.

A new drug application (NDA) for idelalisib was submitted for refractory
indolent non-Hodgkin’s lymphoma (iNHL) on September 11, 2013. Gilead plans to
file for regulatory approval of idelalisib in the European Union later this

About Study 116

Study 116 was a randomized, double-blind, placebo-controlled, Phase 3 study
evaluating the efficacy and safety of idelalisib in combination with
rituximab. The study enrolled 220 adult patients with previously treated
recurrent CLL who had measureable lymphadenopathy with disease progression
less than 24 months following completion of prior therapy, and who required
treatment but were not fit to receive cytotoxic therapy. Eligible patients
were randomized to receive eight infusions of rituximab over 24 weeks plus
either idelalisib (150 mg) or placebo taken orally twice daily continuously
until disease progression or unacceptable toxicity. Patients who progressed on
Study 116 were eligible to receive active idelalisib therapy in a double-blind
extension study (Study 117).

About Idelalisib

Idelalisib is an investigational, highly selective and potent oral inhibitor
of phosphoinositide 3-kinase (PI3K) delta. PI3K delta signaling is critical
for the activation, proliferation, survival and trafficking of B lymphocytes
and is hyperactive in many B-cell malignancies. Idelalisib is being developed
both as a single agent and in combination with approved and investigational

In addition to a Phase 2 study in double-refractory iNHL, Gilead’s clinical
development program for idelalisib includes two Phase 3 studies of idelalisib
in patients with previously treated iNHL and three Phase 3 studies of
idelalisib in patients with previously treated CLL. Combination therapy with
idelalisib and GS-9973, Gilead’s novel spleen tyrosine kinase (Syk) inhibitor,
also is being evaluated in a Phase 2 trial of patients with relapsed or
refractory CLL, iNHL and other lymphoid malignancies.

Additional information about clinical studies of idelalisib and Gilead’s other
investigational cancer agents can be found
Idelalisib and GS-9973 are investigational products and their safety and
efficacy have not yet been established.

AboutGilead Sciences

Gilead Sciencesis a biopharmaceutical company that discovers, develops and
commercializes innovative therapeutics in areas of unmet medical need. The
company’s mission is to advance the care of patients suffering from
life-threatening diseases worldwide. Headquartered inFoster City, California,
Gilead has operations inNorth America,EuropeandAsia Pacific.

Forward-Looking Statement

This press release includes forward-looking statements within the meaning of
the Private Securities Litigation Reform Act of 1995 that are subject to
risks, uncertainties and other factors, including the possibility of
unfavorable results from clinical trials involving idelalisib, including in
combination with GS-9973 or other product candidates. Gilead may also be
unable to file for regulatory approval for idelalisib for CLL with the FDA or
for CLL and iNHL in the European Union in the currently anticipated timelines.
In addition, the pending new drug application for idelalisib for iNHL may not
be approved by the FDA, and if marketing approval is granted, there may be
significant limitations on its use. As a result, idelalisib may never be
successfully commercialized. Further, Gilead may make a strategic decision to
discontinue development of idelalisib if, for example, Gilead believes
commercialization will be difficult relative to other opportunities in its
pipeline. These risks, uncertainties and other factors could cause actual
results to differ materially from those referred to in the forward-looking
statements. The reader is cautioned not to rely on these forward-looking
statements. These and other risks are described in detail in Gilead’s
Quarterly Report on Form 10-Q for the quarter endedJune 30, 2013, as filed
with theU.S. Securities and Exchange Commission. All forward-looking
statements are based on information currently available to Gilead, and Gilead
assumes no obligation to update any such forward-looking statements.

 For more information onGilead Sciences, please visit the company’s website, follow Gilead on Twitter (@GileadSciences) or call Gilead
             Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.


Gilead Sciences, Inc.
Patrick O’Brien, 650-522-1936 (Investors)
Nathan Kaiser, 650-522-1853 (Media)
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