Event-free survival is defined as the time from the date of randomization to the first occurrence of (whichever came first) progressive disease, death, or additional Non-Hodgkins Lymphoma (NHL) therapy due to disease-related symptoms, threatened end-organ function, cytopenias secondary to NHL, massive bulk disease, or steady progression over at least 6 months. Progressive disease is defined as at least a 50% increase in the sum of the perpendicular diameters of all measurable lesions and the appearance of new lesions at least 1.4 centimeters (cm) x 1.4 cm (i.e., 2.0 cm\^2) by radiographic evaluation or greater than 1.0 cm by palpation upon physical examination.

Progression-free survival is defined as the time from the initial date of dosing to the first documented disease progression or death. Disease assessment was based on the International Workshop to Standardize Response Criteria (IWSRC) for Non-Hodgkin's Lymphoma (NHL). Progression is defined as at least a 50% increase in the sum of the perpendicular diameters of all measurable lesions and the appearance of new lesions at least 1.4 centimeters (cm) x 1.4 cm (i.e., 2.0 cm\^2) by radiographic evaluation or greater than 1.0 cm by palpation upon physical examination.

Responders are defined as participants with Complete Response (CR: disappearance of all clinical and radiological evidence of lymphoma), Clinical Complete Response (CCR: all criteria met for CR, except there is a residual nodal mass \>15 millimeters), or Partial Response (PR: 50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions with no new lesions). Response is based on objective evaluation, using the guidelines developed by The International Workshop to Standardize Response Criteria, independent of the investigator's evaluation.

Hematology parameter grades were summarized according to the National Cancer Institute's (NCI) Common Terminology Criteria for Adverse Events (CTCAE), version 2.0. Grade 1, mild; Grade 2, moderate; Grade 3, severe; Grade 4, life-threatening or disabling; Grade 5, death. Data are presented for those participants who experienced Grade 4 toxicities. Grade 4 hematological toxicities included absolute neutrophil count (ANC) (calculated) \<1000 cells/millimeters cubed (mm\^3), white blood cells (WBC) \<2000 cells/mm\^3, platelets \<50000 cells/mm\^3, and hemoglobin \< 8.0 grams/deciliter.

An AE was defined as any untoward medical occurrence in a participant administered a pharmaceutical product and does not necessarily have to have a causal relationship (association) with this treatment. Therefore, an AE was any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not it was considered to be related to the medicinal product. Laboratory abnormalities were recorded as AEs only if they were associated with clinical sequelae and/or required an intervention.

All noxious and unintended responses to a study treatment related to any dose were considered as TRAEs. A response to a study treatment indicates that a causal relationship between a study drug and an adverse event was at least a reasonable possibility, i.e., the relationship cannot be ruled out.

Adverse events were graded using the Common Toxicity Criteria from the Cancer Therapy Evaluation Program, Division of Cancer Therapy, National Cancer Institute. Grades: 0 = No adverse event or within normal limits; 1 = Mild adverse event; 2 = Moderate adverse event; 3 = Severe and undesirable adverse event; 4 = Life-threatening or disabling adverse event; 5 = Death related to adverse event.

All of the treatment-related grade 3 (severe and undesirable) and grade 4 (life-threatening or disabling) adverse events experienced by the participants were recorded.

An SAE was defined as any event occurring at any dose that results in any of the following outcomes: death, a life threatening adverse drug experience (at immediate risk of death from the experience as it occurred), inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant disability/incapacity, or a congenital anomaly/birth defect. Important medical events that may not result in death, be life-threatening, or require hospitalization may be considered to be a serious adverse drug experience when based upon appropriate medical judgment.

All of the treatment-related SAEs experienced by the participants were recorded.

AEs were graded using the Common Toxicity Criteria from the Cancer Therapy Evaluation Program, Division of Cancer Therapy, National Cancer Institute. Grades: 0 = No AE or within normal limits; 1 = Mild AE; 2 = Moderate AE; 3 = Severe and undesirable AE; 4 = Life-threatening or disabling AE; 5 = Death related to AE. mm, millimeters; mm\^3, millimeters cubed. Grade 3 and Grade 4 AEs are reported to focus on the most severe AEs.

All noxious and unintended responses to a study treatment related to any dose were considered as TRAEs. A response to a study treatment indicates that a causal relationship between a study drug and an adverse event was at least a reasonable possibility, i.e., the relationship cannot be ruled out.

The administration of murine antibodies may form HAMA. A HAMA assay was performed using the ImmunoSTRIP HAMA IgG enzyme-linked immune absorbent assay by a central laboratory (Covance Classic Laboratory Services, Indianapolis, IN). Fludarabine, a known immunosuppressant, might decrease HAMA production in addition to reducing bone marrow involvement. To be "positive," a participant had to have a positive HAMA assessment at any follow-up visit (Weeks 12 and 25; Months 12, 18, and 24).

Kaplan-Meier estimates of the time to HAMA positivity (days from the first fludarabine dose) was determined for participants who converted to HAMA positivity.

The number of participants with elevated TSH levels is reported. An elevated TSH level indicates that an insufficient amount of the thyroid hormone is being produced. Insufficient thyroid hormone production is known as hypothyroidism. The normal range of TSH is between 0.2 and 6.1 milliunits per liter (mU/L).

Thyroid medication included any prescribed medication for the treatment of thyroid dysfunction.

Nadir was defined as the lowest laboratory value recorded up to 120 days following the therapeutic dose (or dosimetric dose for participants who did not receive the therapeutic dose).

Nadir was defined as the lowest laboratory value recorded up to 120 days following the therapeutic dose (or dosimetric dose for participants who did not receive the therapeutic dose).

Nadir was defined as the lowest laboratory value recorded up to 120 days following the therapeutic dose (or dosimetric dose for participants who did not receive the therapeutic dose).

Nadir was defined as the lowest laboratory value recorded up to 120 days following the therapeutic dose (or dosimetric dose for participants who did not receive the therapeutic dose).

Adverse events were graded using the Common Toxicity Criteria from the Cancer Therapy Evaluation Program, Division of Cancer Therapy, National Cancer Institute. Grades (G): 0=No AE or within normal limits; 1=Mild AE; 2=Moderate AE; 3=Severe and undesirable AE; 4=Life-threatening or disabling AE; 5=Death related to AE. ANC (10\^3/mm\^3): G1=1.5 to \<2.0, G2=1.0 to \<1.5, G3=0.5 to \< 1.0, G4=\<0.5. Hemoglobin (g/dL): G1=10.0 to \<12.0, G2=8.0 to \<10.0, G3=6.5 to \<8.0, G4=\< 6.5. Platelets (10\^3/microliter): G1=75 to \<150, G2=50 to \<75, G3=25 to \<50, G4=\<25.

Adverse events were graded using the Common Toxicity Criteria from the Cancer Therapy Evaluation Program, Division of Cancer Therapy, National Cancer Institute. Grades (G): 0=No AE or within normal limits; 1=Mild AE; 2=Moderate AE; 3=Severe and undesirable AE; 4=Life-threatening or disabling AE; 5=Death related to AE. ANC (10\^3/mm\^3): G1=1.5 to \<2.0, G2=1.0 to \<1.5, G3=0.5 to \< 1.0, G4=\<0.5. Hemoglobin (g/dL): G1=10.0 to \<12.0, G2=8.0 to \<10.0, G3=6.5 to \<8.0, G4=\< 6.5. Platelets (10\^3/microliter): G1=75 to \<150, G2=50 to \<75, G3=25 to \<50, G4=\<25.

An infection is the colonization of a host organism by a parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease. Colloquially, infections are usually considered to be caused by microscopic organisms or microparasites like viruses, bacteria, and viroids, although larger organisms such as macroparasites and fungi can also infect.

An infection is the colonization of a host organism by a parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease. Colloquially, infections are usually considered to be caused by microscopic organisms or microparasites like viruses, bacteria, and viroids, although larger organisms such as macroparasites and fungi can also infect.

Specimen samples of the body fluid are cultured for testing whether the infectious organism is present and grown in the culture media to assess the growth pattern of the organisms present in the specimen.

The culture results could be positive or negative. The positive culture results indicates that the tested participant have the infection under investigation so therapeutic treatment with anti-infective is required.

Anti-infectives are capable of acting against infection, by inhibiting the spread of an infectious agent or by killing the infectious agent outright. Anti-infective is a general term that encompasses antibacterials, antibiotics, antifungals, antiprotozoans, and antivirals.

Supportive care involves interventions that help the participants to achieve comfort but do not affect the course of a disease.

Supportive care involves interventions that help the participants to achieve comfort but do not affect the course of a disease. Supportive care involved administration of granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), red blood cell (RBC) transfusions, erythropoietin, and platelet transfusions.

Complete response (CR) is defined as the complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease. Response is defined as the best response achieved at any evaluation. A confirmed response is defined as a response that was confirmed by two separate response evaluations occurring at least 4 weeks apart.

For participants with CR, clinical CR (CCR), or partial response (PR), duration of response is defined as the time from the first documented response to the first documented progression. CCR is defined as the complete resolution of all disease-related symptoms, but residual foci, thought to be residual scar tissue, are present. Generally, an unchanging lesion \<=2 centimeters (cm) in diameter by radiographic evaluation or \<=1 cm in diameter by physical examination can be considered scar tissue. The extent of disease must be unchanged or decreased upon follow-up evaluations and, if unchanged or if further decreases for 6 months or longer are present, the participant will then be reclassified as a CR (complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease). PR is defined as a \>=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions, with no new lesions.

Time to treatment failure is defined as the time from the dosimetric dose to the first occurrence of treatment withdrawal, a decision to receive additional therapy, study withdrawal, disease progression, or death.

Time to death (overall survival) is defined as the time from the start of retreatment (i.e., the dosimetric dose) to the date of death from any cause.

An AE is defined as any untoward medical occurrence in a participant or clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An SAE is defined as those events that were fatal or immediately life-threatening, and those events that resulted in hospitalization; prolonged an existing hospitalization; or resulted in disability, congenital anomaly, or cancer. Refer to the general AE/SAE module for a complete list of all AEs and SAEs.

Par. with response are those with complete response (CR; complete resolution of all disease-related radiological abnormalities and the disappearance of all signs/symptoms related to disease), complete response unconfirmed (CRu; meets characteristics of CR, except the nodal size hasn't regressed sufficiently, or there is indeterminate bone marrow), or partial response (PR; \>=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions with no new lesions). Participants' LQCR was used as a comparator for subsequent treatment with Iodine I 131TST.

Duration of response is defined as the time from the first documented response (for par. with complete response, complete response unconfirmed, or partial response) until disease progression (DP). DP is defined as a \>=25% increase from the nadir value (lowest laboratory value recorded following administration of the study medication) of the sum of the products of the longest perpendicular diameters of all measurable lesions or the appearance of any new lesion. Individual lesions must be \>2 centimeters (cm) in diameter by radiographic evaluation or \>1 cm in diameter by physical examination.