Subjects with splenic MZL must have an additional measurable lesion, nodal or extranodal, as described in inclusion criterion #;
Histologically confirmed relapsed (response to last treatment >=  months duration) or refractory (no response to last treatment or response duration <  months) indolent/low grade B cell NHL; NOTE: if patient has received previous anti-PD- or anti-PDL- consult with study chair\r\n* Follicular lymphoma, grades ,  and \r\n* Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type\r\n* Splenic and nodal marginal zone lymphoma\r\n* Lymphoplasmacytic lymphoma including Waldenstrom macroglobulinemia;
Patients must have histologically determined indolent NHL that is relapsed or primary refractory after initial therapy; indolent NHL includes the morphologic and clinical variants:\r\n* Follicular lymphoma, grades -a\r\n* Marginal zone lymphoma (extranodal, nodal, or splenic)\r\n** All nodal marginal zone lymphomas are eligible\r\n** Extranodal marginal zone lymphomas of the stomach (gastric mucosa associated lymphoid tissue [MALT] lymphomas) may not be candidates for cure with antibiotics or local radiotherapy; patients who have failed antibiotics or local therapy are eligible for the protocol as long as they have measurable disease\r\n** Splenic marginal zone lymphoma patients may have received prior splenectomy as long as they have measurable disease\r\n* Re-biopsy is not mandated at relapse unless there is clinical suspicion about an alternate diagnosis
Confirmed diagnosis of Marginal Zone Lymphoma or Waldenstroms Macroglobulinemia
Waldenstrom's macroglobulinemia (WM) or marginal zone lymphoma (MZL) based on institutional pathology review; patients may have either previously untreated or relapsed/refractory disease
Previously untreated, histologically confirmed indolent non-Hodgkins lymphoma as follows:\r\n* Follicular lymphoma (World Health Organization [WHO] classification grade , , or a)\r\n* Marginal zone lymphoma including:\r\n** Nodal and splenic marginal zone lymphoma (MZL) who have an indication for systemic therapy\r\n** Extranodal MZL:\r\n*** Nongastric/noncutaneous MZL requiring systemic therapy\r\n*** Cutaneous MZL will be eligible only if they have pathologically confirmed extra-cutaneous disease\r\n*** Gastric MZL only if stage IIIE/IV defined as lymph node involvement on both sides of the diaphragm or with disseminated extranodal disease such as bone marrow or additional extra nodal sites
Marginal zone lymphoma (extranodal, nodal or splenic). Subjects with gastric mucosa-associated lymphoid tissue must have progressed after Helicobacter pylori therapy and radiation. Subjects with splenic marginal zone lymphoma must have prior splenectomy.
Patients must have histologically confirmed, low-grade B-lymphocyte non-Hodgkin lymphoma (NHL) by the World Health Organization classification:\r\n* Follicular lymphoma grades , , and a\r\n* Marginal zone B-cell lymphoma, including extranodal (mucosa-associated lymphoid tissue [MALT]), nodal and splenic\r\n* Excluding:\r\n** Small lymphocytic lymphoma\r\n** Lymphoplasmacytic lymphoma/Waldenstroms macroglobulinemia (WM)
Subjects must have histologically determined B cell NHL that is relapsed or primary refractory after initial therapy\r\n* Follicular lymphoma of any grade\r\n* Marginal zone lymphoma (extranodal, nodal, or splenic); patients with gastric mucosa-associated lymphoid tissue (MALT) must have progressed after Helicobacter pylori (H. pylori) therapy and radiation; patients with splenic marginal zone lymphoma (MZL) must have prior splenectomy
Marginal zone lymphoma (splenic, nodal, or extranodal)
Marginal zone lymphoma (MZL) (splenic, nodal, or extra-nodal)
Non-WM must have at least one bi-dimensionally measurable lesion (which has not been previously irradiated) according to the Lugano Classification. For patients with splenic MZL (Marginal-zone lymphoma) this requirement may be restricted to splenomegaly alone since that is usually the only manifestation of measurable disease.
Follicular lymphoma, marginal zone lymphomas (splenic, nodal, or extranodal/mucosa-associated lymphoid tissue [MALT] type)\r\n* Primary refractory disease\r\n* Relapse after >=  prior regimens\r\n* Relapse/progression after autologous HSCT
Marginal zone B-cell lymphoma or follicular lymphoma that has progressed after at least two prior therapies (excluding single agent Rituxan)
Indolent lymphoma Phase  cohort: Marginal zone or follicular lymphoma, relapsed or refractory to standard approved therapies
Indolent non-Hodgkins lymphoma, which may include the following:\r\n* Nodal marginal zone lymphoma\r\n* Extranodal marginal zone lymphoma mucosa-associated lymphoid tissue (MALT)\r\n* Splenic marginal zone lymphoma\r\n* Follicular lymphoma grade -a with low tumor burden, Follicular Lymphoma International Prognostic Index (FLIPI)  risk category of either low (i.e. no risk factors) or intermediate (- risk factors), and with no B symptoms. B symptoms are defined as:\r\n** Fever (i.e., temperature >  degree Celsius (C) [> . degree Fahrenheit (F)]) for  consecutive days\r\n** Weight loss exceeding % of body weight in  months\r\n** Drenching night sweats\r\n* Lymphoplasmacytic lymphoma\r\n*** Low tumor burden is defined as normal lactate dehydrogenase, largest nodal or extranodal mass less than  cm, up to three nodal sites containing nodes with a diameter greater than  cm, no clinically significant serous effusions detectable by physical examination or positron emission tomography (PET)/computed tomography (CT) scan, and spleen enlargement up to  cm by CT without any evidence of portal hypertension
Prior history of malignancies, other than follicular or marginal zone lymphoma, unless the subject has been free of the disease for ?  years.
Marginal zone lymphoma (MZL) (splenic, nodal, or extra-nodal).
Histologically confirmed diagnosis of follicular lymphoma (FL) grades ,  or a, marginal zone lymphoma (including nodal or splenic marginal zone B-cell lymphoma and mucosa-associated lymphoid tissue [MALT] lymphoma), lymphoplasmacytic lymphoma/Waldenstrm macroglobulinemia, chronic lymphocytic leukemia (CLL).
Marginal zone lymphoma (MZL) (splenic, nodal, or extranodal)
Follicular lymphoma, Mucosa-Associated Lymphoid Tissue (MALT) and nodular marginal zone are not included into this therapeutic study
Follicular lymphoma, MALT and nodular marginal zone are not included into this therapeutic study
Cluster of differentiation  (CD)-positive indolent B-cell non-Hodgkin's lymphoma (follicular lymphoma or splenic, nodal or extranodal marginal zone lymphoma)
For participants with symptomatic splenic, nodal, or non-gastric extranodal marginal zone lymphoma: disease that is de novo or has relapsed following local therapy (i.e. surgery or radiotherapy) and requires therapy as assessed by the investigator
Histologically confirmed marginal zone lymphoma, including extranodal, nodal, and splenic subtypes.
Follicular lymphoma, marginal zone lymphomas (splenic, nodal, or extranodal/mucosa-associated lymphoid tissue [MALT] type)\r\n* Chemotherapy-refractory disease\r\n* Relapse after >=  prior regimens\r\n* Relapse/progression after autologous HSCT
Marginal zone lymphoma (MZL) (splenic, nodal, or extra-nodal)
Marginal zone lymphoma (MZL) (splenic, nodal, or extranodal)
Histologically documented marginal zone lymphoma including splenic, nodal, and extranodal sub-types; subjects with splenic MZL must have an additional measurable lesion, nodal or extranodal, as described in inclusion criteria 
Small lymphocytic, lymphoplasmacytic, marginal zone lymphoma, and follicular lymphoma; Grades ,  and a, defined according to World Health organization (WHO) guidelines. [Tefferi, ]
Marginal zone lymphoma
splenic marginal zone B-cell lymphoma
extra-nodal marginal zone lymphoma of mucosa-associated lymphoid tumor (MALT) type
nodal marginal zone B-cell lymphoma
Inclusion Criteria:\n\n        Each of the following criteria must be met in order for a patient to be considered eligible\n        for registration:\n\n          -  Biopsy proven (with hematopathology review at one of the participating sites to\n             confirm correct histology in accordance with World Health Organization) indolent\n             lymphoma to include the following diagnoses:\n\n               -  Grade , , or a follicular lymphoma\n\n               -  Small lymphocytic lymphoma (CLL excluded)\n\n               -  Marginal zone lymphoma (nodal or splenic)\n\n               -  Mucosal-associated lymphoid tissue\n\n          -  Measurable disease defined by Lugano criteria\n\n          -  No prior anti-lymphoma systemic therapy; prior radiation therapy allowed\n\n          -  Age  or over\n\n          -  Ann Arbor stages II, III or IV\n\n          -  Patients with follicular lymphoma must have PET FDG-avid lymphoma and fulfill Low\n             tumor burden by Groupe D'Etude des Lymphomes Folliculaires (GELF) criteria:\n\n               -  No mass >  cm\n\n               -  <  distinct masses of greater than  cm\n\n               -  No B symptoms\n\n               -  No splenomegaly >  cm by computed tomography (CT) scan\n\n               -  No risk of vital organ compression\n\n               -  No leukemic phase > /l circulating lymphocytes (except for in patients with\n                  splenic marginal zone diagnosis)\n\n               -  No cytopenias (platelets < ,/l, hemoglobin <  g/dl, or absolute\n                  neutrophil count < /l)\n\n        Exclusion Criteria:\n\n        The following criteria will prevent inclusion of an inappropriate subject into the trial:\n\n          -  Osteoporosis requiring prescription treatment\n\n          -  Known symptomatic primary hyperparathyroidism\n\n          -  Hypercalcemia defined as above the institutional normal range (corrected for albumin\n             when albumin levels are below normal)\n\n          -  History of calcium-related kidney stones\n\n          -  Creatinine > .X above upper limit of normal\n\n          -  Women who are known to be pregnant or who plan to become pregnant while on rituximab\n             treatment