First Line Therapy of Advanced Stage Follicular Lymphoma in Patients < 60 Years Not Eligible fo Standard Immunochemotherapy and in All Patients ≥ 60 Years

Inclusion Criteria:

* Medically nonfit" patients \< 60 years defined by

  o ECOG \> 2 or ECOG 0-2 with co-morbidities excluding intensive therapy according to local investigator's discretion
* All patients ≥ 60 years in case of decision of investigator and patient to apply a reduced Treatment
* Documentation of the CIRS-G, IADL, G8 and ECOG Scores before start of treatment
* Histologically confirmed follicular lymphoma grade I, II or IIIa with material available for central pathology review
* Stage III/IV or stage II without the option of curative radiotherapy
* Age \> 18 years
* No prior therapy
* Presence of at least one of the following symptoms or conditions requiring initiation of treatment:

  * Bulky disease according to the GELF criteria: nodal or extranodal mass \> 7cm in its greater diameter
  * B symptoms (fever, drenching night sweats, or unintentional weight loss of \>10% of normal body weight over a period of 6 months or less)
  * Hematopoietic insufficiency (at least one of the following: granulocytopenia \<1500 cells/μl, Hb \< 10 g/dl, thrombocytopenia \<100.000 cells/μl)
  * Compressive syndrome
  * Pleural/peritoneal effusion
  * Symptomatic nodal or extranodal manifestations
* At least one bi-dimensionally measurable lesion (\> 1.5 cm in its largest dimension by CT scan or MRI)
* Adequate hematologic function (unless abnormalities are related to NHL), defined as follows:

  * hemoglobin ≥ 9.0 g/dl
  * absolute neutrophil count ≥ 1500 /μL
  * platelet count ≥ 75000 /μl
* Women who are not breast feeding, are using effective contraception, are not pregnant and agree not to become pregnant during participation in the trial and during the 18 months thereafter.
* Men who agree not to father a child during participation in the trial and during the 18 months thereafter.
* Written informed consent form

Exclusion Criteria:

"Medically fit" patients \< 60 years with the option for more intensive induction therapy such as R-CHOP

* Transformation to high-grade lymphoma (secondary to "low-grade" follicular lymphoma)
* Grade IIIb follicular lymphoma
* Presence or history of CNS disease (either CNS lymphoma or lymphomatous meningitis).
* Regular use of corticosteroids during the last 4 weeks, unless administered at a dose equivalent to \< 20 mg/day prednisone.
* Prior (\< 3 years) or concomitant malignancies except non-melanoma skin cancer or adequately treated in situ cervical cancer.
* Major surgery (excluding lymph node biopsy) within 28 days prior to registration.
* Necessity of rapid cytoreduction
* Serious underlying medical conditions, which could impair the ability of the patient to tolerate the therapy offered in this trial (e.g. ongoing infection, uncontrolled diabetes mellitus, gastric ulcers, active autoimmune disease).
* Severe hepatic impairment (serum bilirubin \> 3.0 mg/dl)
* Known sensitivity or allergy to murine products
* Known hypersensitivity to any of the study drugs
* Treatment within a clinical lymphoma trial within 30 days prior to trial entry
* Positive test results for chronic HBV infection (defined as positive HBsAg serology) (mandatory testing) Patients with occult or prior HBV infection (defined as negative HBsAg and positive total HBcAb) may be included if HBV DNA is undetectable, provided that they are willing to undergo monthly DNA testing. Patients who have protective titers of hepatitis B surface antibody (HBSAb) after vaccination or prior but cured hepatitis B are eligible.
* Positive test results for hepatitis C (mandatory hepatitis C virus \[HCV\] antibody serology testing). Patients positive for HCV antibody are eligible only if PCR is negative for HCV RNA
* Known history of HIV seropositive status.
* Patients with a history of confirmed PML
* Vaccination with a live vaccine within 28 days prior to registration
* Prior organ, bone marrow or peripheral blood stem cell transplantation
* Any other co-existing medical or psychological condition that will preclude participation in the study or compromise the ability to understand its nature,meaning and implications