Inclusion Criteria:

          -  Confirmed diagnosis of chronic lymphocytic leukemia (CLL) or small lymphocytic
             lymphoma according to the revised iwCLL criteria19 with biopsy proven transformation
             to diffuse large B-cell lymphoma, consistent with RS according to the 2016 WHO
             classification

          -  Both patients with previously treated or treatment-naïve CLL are eligible

          -  Age greater than or equal to 18 years

          -  Eastern Cooperative Oncology Group (ECOG) performance status <3

          -  Patients must meet the following hematologic criteria at screening, unless they have
             significant bone marrow involvement of either CLL or RS cells confirmed on biopsy:
             absolute neutrophil count ≥1.0 G/L, platelet count ≥50 G/L independent of transfusion
             within 7 days of screening

          -  Subject must have adequate coagulation, renal, and hepatic function at screening

          -  Adequate left ventricular ejection function (> 50 %)

          -  Patients who have undergone prior allogeneic hematopoietic stem-cell transplantation
             (HSCT) are eligible as long as they do not have significant active graft versus host
             disease and that their transplant day 0 is > 6 months from their first dose of
             protocol therapy

          -  Female patients of child bearing potential must have negative pregnancy test and use
             an effective method of birth control during treatment period and 48h thereafter; Males
             must use an effective method of birth control during treatment period and 48h
             thereafter.

          -  Ability to understand and the willingness to sign a written informed consent document

        Exclusion Criteria:

          -  Patients with the Hodgkin variant of RS

          -  Patients with previously treated RS

          -  History or presence of clinically relevant disorder affecting the central nervous
             system (CNS)

          -  Known active DLBCL in the CNS (confirmed by cerebrospinal fluid analysis)

          -  Steroids treatment (≥ 20 mg for one week) before inclusion

          -  HSCT within 6 months before inclusion

          -  Active graft-versus-host disease

          -  History of other malignancies, except: i) malignancy treated with curative intent and
             with no recurrence over the last 5 years ii) adequately treated non-melanoma skin
             cancer without evidence of disease iii) adequately treated carcinoma in situ without
             evidence of disease

          -  History of human immunodeficiency virus

          -  Hepatitis B or C seropositivity (unless clearly due to vaccination)

          -  Pregnant or breastfeeding women

          -  Unwilling or unable to participate in all required study evaluations and procedures.

          -  Unable to understand the purpose and risks of the study and to provide a signed and
             dated informed consent form and authorization to use protected health information (in
             accordance with national and local subject privacy regulations)

          -  Abnormal screening laboratory values as defined as following: a) serum glutamate
             oxaloacetate transaminase and/or serum glutamate pyruvate transaminase and/or alkaline
             phosphatase > or =5 x upper limit of normal (ULN); b) Total bilirubin > or = 1.5 x
             ULN, unless due to Gilbert's disease; c) Creatinine > or = 2.0 x ULN or creatinine
             clearance <50 mL/min (calculated).

          -  Fertile male and female patients who cannot or do not wish to use an effective method
             of contraception during treatment and for 48h after the final treatment used for the
             purposes of the study

          -  Treatment with other investigational agent or participating to another trial within 30
             days prior to entering the study

          -  No affiliated to social security