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N Engl J Med. 2015 Dec 17;373(25):2425-37. doi: 10.1056/NEJMoa1509388. Epub 2015 Dec 6.

Ibrutinib as Initial Therapy for Patients with Chronic Lymphocytic Leukemia.

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From the University of Texas MD Anderson Cancer Center, Houston (J.A.B.); Azienda Ospedaliera Niguarda Cà Granda (A.T.) and Università Vita-Salute San Raffaele and IRCCS Istituto Scientifico San Raffaele (P.G.), Milan, and the Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara (G.G.) - all in Italy; Wilmot Cancer Institute, University of Rochester, Rochester, NY (P.M.B.); Medical University of Lodz and Copernicus Memorial Hospital, Lodz (T.R.), the Department of Cancer Prevention, School of Public Health, Medical University of Silesia, Katowice (S.G.), and the Department of Hematology, University Clinical Center of Medical University of Gdansk, Gdansk (A.H.) - all in Poland; Tom Baker Cancer Centre, Calgary, AB, Canada (C.O.); Rabin Medical Center, Beilinson Hospital and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (O.B.), and Hadassah University Hospital, Hebrew University Medical School, Jerusalem (A.P.) - both in Israel; Leeds Teaching Hospitals, St. James Institute of Oncology, Leeds (P.H.), Kings College Hospital, London (S.D.), Royal Bournemouth Hospital, Bournemouth (H.M.), and University of Oxford, Oxford (A.S.) - all in the United Kingdom; Washington University School of Medicine, St. Louis (N.L.B.); Jiangsu Province Hospital, Nanjing, China (J.L.); North Shore Hospital, Auckland, New Zealand (D. Simpson); Stanford University School of Medicine, Stanford (S.C.), City of Hope National Medical Center, Duarte (T.S.), Pharmacyclics, Sunnyvale (D. Suri, M.C., F.C., L.S., D.F.J.), and Moores Cancer Center, University of California, San Diego, San Diego (T.J.K.) - all in California; St. Vincent's Hospital, University of Melbourne (H.Q.), and Peter MacCallum Cancer Centre and St. Vincent's Hospital (C.S.T.), Melbourne, VIC, Australia; Institute of Blood Pathology and Transfusion Medicine, National Academy of Medical Sciences of Ukraine, Lviv, Ukraine (Z.M.); Norton Cancer Institute, Louisville, KY (D.A.S.);



Chronic lymphocytic leukemia (CLL) primarily affects older persons who often have coexisting conditions in addition to disease-related immunosuppression and myelosuppression. We conducted an international, open-label, randomized phase 3 trial to compare two oral agents, ibrutinib and chlorambucil, in previously untreated older patients with CLL or small lymphocytic lymphoma.


We randomly assigned 269 previously untreated patients who were 65 years of age or older and had CLL or small lymphocytic lymphoma to receive ibrutinib or chlorambucil. The primary end point was progression-free survival as assessed by an independent review committee.


The median age of the patients was 73 years. During a median follow-up period of 18.4 months, ibrutinib resulted in significantly longer progression-free survival than did chlorambucil (median, not reached vs. 18.9 months), with a risk of progression or death that was 84% lower with ibrutinib than that with chlorambucil (hazard ratio, 0.16; P<0.001). Ibrutinib significantly prolonged overall survival; the estimated survival rate at 24 months was 98% with ibrutinib versus 85% with chlorambucil, with a relative risk of death that was 84% lower in the ibrutinib group than in the chlorambucil group (hazard ratio, 0.16; P=0.001). The overall response rate was higher with ibrutinib than with chlorambucil (86% vs. 35%, P<0.001). The rates of sustained increases from baseline values in the hemoglobin and platelet levels were higher with ibrutinib. Adverse events of any grade that occurred in at least 20% of the patients receiving ibrutinib included diarrhea, fatigue, cough, and nausea; adverse events occurring in at least 20% of those receiving chlorambucil included nausea, fatigue, neutropenia, anemia, and vomiting. In the ibrutinib group, four patients had a grade 3 hemorrhage and one had a grade 4 hemorrhage. A total of 87% of the patients in the ibrutinib group are continuing to take ibrutinib.


Ibrutinib was superior to chlorambucil in previously untreated patients with CLL or small lymphocytic lymphoma, as assessed by progression-free survival, overall survival, response rate, and improvement in hematologic variables. (Funded by Pharmacyclics and others; RESONATE-2 number, NCT01722487.).

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