May 15, 2013
Gilead Announces Response Data from Phase 2 Study of Idelalisib for Previously Untreated Chronic Lymphocytic Leukemia
-- Regimen Achieves 97 Percent Overall Response Rate with Estimated Progression-Free Survival at 24 Months of 93 Percent --
-- Results from Study 101-08 and Other Idelalisib Clinical Studies
to Be Presented at
CLL is a slow-growing cancer that induces the production of too many
mature white blood cells. It is the second most common type of leukemia
“New therapies that can drive CLL into remission while potentially
avoiding or delaying the need for chemotherapy would represent a much
needed clinical advance,” said Susan M. O’Brien, MD,
Among the 64 patients in the study, Kaplan-Meier estimated PFS at 24 months was 93 percent. The median time on treatment was 14 months, with 33 patients remaining on treatment. The median time to response was two months. No relapses on study have been reported. The nine patients with chromosome 17p deletion (del 17p) (n=6) or mutation in the TP53 gene (n=3), which have been linked to poor prognosis, all responded to therapy including three with a complete response. Ninety-four percent of patients with thrombocytopenia at baseline responded to treatment (16/17), as did all patients with anemia at baseline (17/17). Of patients with systemic symptoms such as extreme fatigue, fever, night sweats or weight loss (known as “B symptoms”) at baseline, 77 percent (20/26) were asymptomatic by eight weeks.
Patients completing 48 weeks of therapy without progression could continue to receive idelalisib in an extension study. Forty-three patients completed 48 weeks of treatment (21 discontinued – 17 due to adverse events, three due to death and one due to other reasons); 40 patients entered the extension study and 33 remain on treatment.
During the primary and extension study, Grade 3 diarrhea and/or colitis was reported in 33 percent of patients, Grade ≥3 pneumonia in 17 percent and Grade ≥3 transaminase elevations (measure of liver function) in 23 percent of patients.
“These results demonstrate for the first time idelalisib’s potential
benefit for patients with a previously untreated hematological
Idelalisib’s clinical and safety profile for a number of blood cancers
will be characterized in six additional oral or poster presentations at
Chronic Lymphocytic Leukemia (CLL)
- Final results of a Phase 1 study of idelalisib in patients with relapsed or refractory CLL (Abstract #7003; oral session).
- Update on a Phase 1 study of idelalisib in combination with rituximab and/or bendamustine in patients with relapsed or refractory CLL (Abstract #7017; poster session).
Indolent Non-Hodgkin’s Lymphoma (iNHL)
- Combinations of the PI3K delta inhibitor idelalisib with rituximab and/or bendamustine are tolerable and highly active in patients with previously treated, indolent non-Hodgkin lymphoma: Updated results from a Phase 1 study (Abstract #8500; oral session).
- Final results of a Phase 1 study of idelalisib, a selective inhibitor of PI3K delta, in patients with relapsed or refractory indolent non-Hodgkin lymphoma (Abstract #8526; poster session).
Mantle Cell Lymphoma (MCL)
- Final results of a Phase 1 study of idelalisib, a selective inhibitor of PI3K delta in patients with relapsed or refractory mantle cell lymphoma (Abstract #8519; clinical science symposium).
- Preliminary results of PI3K delta inhibitor idelalisib treatment in combination with everolimus, bortezomib, or bendamustine/rituximab in patients with previously treated mantle cell lymphoma (Abstract #8501; oral session).
About Study 101-08
Study 101-08 is an open-label, single-arm Phase 2 trial that enrolled 64 treatment-naïve patients ≥65 years old with CLL or small lymphocytic lymphoma (SLL), a less common form of the disease. Patients received intravenous rituximab 375 mg/m2 weekly for eight weeks and oral idelalisib 150 mg twice daily for 48 weeks. The primary endpoint of the study is overall response rate, defined as the proportion of patients achieving a complete or partial response with this regimen (response definitions based on standard criteria). Patients completing 48 weeks of therapy without progression could continue to receive idelalisib in an extension study.
Idelalisib is an investigational, targeted, highly selective oral inhibitor of phosphoinositide 3-kinase (PI3K) delta, a molecular target that is critical for the activation, proliferation and survival of B lymphocytes. PI3K delta signaling is hyperactive in many B-cell leukemias and lymphomas and drives proliferation, survival and trafficking to lymphoid tissue. Idelalisib is being developed both as a single agent and in combination with approved and investigational therapies.
Gilead’s clinical development program for idelalisib includes three Phase 3 studies evaluating the drug in combination with approved therapies for patients with previously treated CLL, and two Phase 3 studies of idelalisib in combination with approved therapies for patients with previously treated indolent non-Hodgkin’s lymphoma (iNHL). In addition, combination therapy with idelalisib and GS-9973, Gilead’s novel spleen tyrosine kinase (Syk) inhibitor, is being studied in a Phase 2 trial of patients with relapsed or refractory CLL, iNHL and other lymphoid and hematological malignancies.
Additional information about clinical studies of idelalisib and Gilead’s other investigational cancer agents can be found at www.clinicaltrials.gov. Idelalisib and GS-9973 are investigational products and their safety and efficacy have not yet been established.
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 risks
related to the possibility of unfavorable results from clinical trials
involving idelalisib, including in combination with GS-9973 or other
product candidates. Gilead also faces risks related to its ability to
enroll patients in a Phase 3 clinical study in treatment-naïve CLL
patients or other studies and may need to modify or delay this study or
other studies. 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 ended
For more information on
Gilead Sciences, Inc.
Patrick O’Brien, 650-522-1936
Nathan Kaiser, 650-522-1853