In the CLL2-BAG-trial, a total of 62 patients of an allcomer CLL population (irrespective of physical fitness, previous therapies and prognostic factors) with an indication for treatment will be included. Patient will receive 2 cycles of debulking treatment with Bendamustine unless contraindications (e.g. refractoriness) are present or a debulking is not indicated due to a low tumor load. Afterwards, 6 cycles of induction treatment with GA101 (obinutuzumab, 3 doses in the first cycle and monthly in cycles 2-6) and ABT-199 (venetoclax, continuously starting in cycle 2 with a low dose escalation) will be applied. The primary endpoint overall response rate will be assessed at final restaging (2 months after end of induction treatment). Patients benefitting from treatment receive further therapy with GA101 (3 monthly) and ABT-199 (continuously) in a maintenance phase for up to 24 months. Maintenance treatment will be stopped in case of achievement of a complete remission and confirmation of MRD (minimal residual disease) negativity in peripheral blood or if unacceptable toxicity or progression occurs.