Inclusion Criteria:

          1. Documented CLL requiring treatment according to iwCLL criteria

          2. Age at least 18 years

          3. Life expectancy ≥ 6 months

          4. Ability and willingness to provide written informed consent and to adhere to the study
             visit schedule and other protocol requirements

          5. Adequate bone marrow function indicated by a platelet count >30 x10^9/l (unless
             directly attributable to CLL infiltration of the bone marrow, proven by bone marrow
             biopsy)

          6. Creatinine clearance ≥70ml/min directly measured with 24hr urine collection or
             calculated according to the modified formula of Cockcroft and Gault (for men: GFR ≈
             ((140 - age) x bodyweight) / (72 x creatinine), for women x 0, 85). For patients with
             creatinine values within the normal range the calculation of the clearance is not
             necessary. Dehydrated patients with an estimated creatinine clearance less than 70
             ml/min may be eligible if a repeat estimate after adequate hydration is > 70 ml/min

          7. Adequate liver function as indicated by a total bilirubin≤ 2 x, AST/ALT ≤ 2.5 x the
             institutional ULN value, unless directly attributable to the patient's CLL or to
             Gilbert's Syndrome

          8. Negative serological testing for hepatitis B (HBsAg negative and anti-HBc negative;
             patients positive for anti-HBc may be included if PCR for HBV DNA is negative and
             HBV-DNA PCR is performed every month until 12 months after last treatment cycle),
             negative testing for hepatitis C RNA within 6 weeks prior to registration

          9. Eastern Cooperative Oncology Group Performance Status (ECOG) performance status 0-2

        Exclusion Criteria:

          1. Any prior CLL-specific therapies (except corticosteroid treatment administere due to
             necessary immediate intervention; within the last 10 days before start of study
             treatment, only dose equivalents of 20 mg prednisolone are permitted).

          2. Transformation of CLL (Richter transformation)

          3. Decompensated hemolysis, defined as ongoing hemoglobin drop in spite of three more
             concurrent treatments being administered for hemolysis

          4. Detected del(17p) or TP53 mutation

          5. Patients with a history of PML

          6. Any comorbidity or organ system impairment rated with a single CIRS (cumulative
             illness rating scale) score of 4 (excluding the eyes/ears/nose/throat/larynx organ
             system), a total CIRS score of more than 6 or any other life-threatening illness,
             medical condition or organ system dysfunction that, in the investigator´s opinion,
             could comprise the patients safety or interfere with the absorption or metabolism of
             the study drugs (e.g, inability to swallow tablets or impaired resorption in the
             gastrointestinal tract)

          7. Urinary outflow obstruction

          8. Malignancies other than CLL currently requiring systemic therapies, not being treated
             in curative intention before (unless the malignant disease is in a stable remission
             due to the discretion of the treating physician) or showing signs of progression after
             curative treatment

          9. Uncontrolled or active infection

         10. Patients with known infection with human immunodeficiency virus (HIV)

         11. Requirement of therapy with strong CYP3A4 and CYP3A5 inhibitors/inducers

         12. Anticoagulant therapy with warfarin or phenoprocoumon, (rotation to alternative
             anticoagulation is allowed, but note that patients being treated with NOAKs can be
             included, but must be properly informed about the potential risk of bleeding under
             treatment with ibrutinib)

         13. History of stroke or intracranial hemorrhage within 6 months prior to registration

         14. Use of investigational agents which might interfere with the study drug within 28 days
             prior to registration

         15. Vaccination with live vaccines 28 days prior to registration

         16. Major surgery less than 30 days before start of treatment

         17. History of severe allergic or anaphylactic reactions to humanized or murine monoclonal
             antibodies, known sensitivity or allergy to murine products

         18. Known hypersensitivity to any active substance or to any of the excipients of one of
             the drugs used in the trial

         19. Pregnant women and nursing mothers (a negative pregnancy test is required for all
             women of childbearing potential within 7 days before start of treatment; further
             pregnancy testing will be performed regularly)

         20. Fertile men or women of childbearing potential unless:

               1. surgically sterile or ≥ 2 years after the onset of menopause

               2. willing to use two methods of reliable contraception including one highly
                  effective contraceptive method (Pearl Index <1) and one additional effective
                  (barrier) method during study treatment and for 18 months after the end of study
                  treatment

         21. Legal incapacity

         22. Prisoners or subjects who are institutionalized by regulatory or court order

         23. Persons who are in dependence to the sponsor or an investigator