Number of Participants (Par.) With Confirmed Response as Assessed by the Investigator
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
Number of Participants With Confirmed Response Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Participants receiving Unlabeled TST with progressive disease (defined as a >=25% increase from the nadir value of the sum of the products of the longest perpendicular diameters of all measureable 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.) were assessed separately before and after receiving the crossover treatment of I 131 TST for confirmed response, which included participants with CR, CCR, and PR.
Number of Participants With Confirmed Complete Response (CR) as Assessed by the Investigator
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.
Number of Participants (Par.) With a Confirmed Complete Response as Assessed by the Masked Independent Randomized Radiology and Oncology Review (MIRROR) Panel
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
Number of Participants With Confirmed Complete Response (CR) Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Participants receiving Unlabeled TST with progressive disease were assessed separately before and after receiving the crossover treatment of I 131 TST for CR. 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.
Number of Participants With Confirmed Clinical Complete Response (CCR) as Assessed by the Investigator
CCR is defined as the complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present. Generally, an unchanging lesion =<2 cm in diameter by radiographic evaluation or =<1 cm in diameter by physical examination can be considered scar tissue.
Number of Participants With Confirmed Clinical Complete Response (CCR) Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Participants receiving Unlabeled TST with progressive disease were assessed separately before and after receiving the crossover treatment of I 131 TST for CCR. CCR is defined as the complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present. Generally, an unchanging lesion =<2 cm in diameter by radiographic evaluation or =<1 cm in diameter by physical examination can be considered scar tissue.
Number of Participants With Confirmed Complete Response Plus Clinical Complete Response (CR + CCR) as Assessed by the Investigator
CCR is defined as the complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present. Generally, an unchanging lesion =<2 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. If the extent of disease was unchanged or if further decreases occurred for 6 months or longer, the participant was reclassified as having a CR.
Number of Participants With Confirmed Complete Response Plus Clinical Complete Response (CR + CCR) Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Participants receiving Unlabeled TST with progressive disease were assessed separately before and after receiving the crossover treatment of I 131 TST for CR + CCR.
Number of Participants With Confirmed Partial Response (PR) as Assessed by the Investigator
Confirmed 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.
Number of Participants With Confirmed Partial Response (PR) Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Participants receiving Unlabeled TST with progressive disease were assessed separately before and after receiving the crossover treatment of I 131 TST confirmed PR. Confirmed PR is defined as a >=50 percent reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions, with no new lesions.
Number of Participants (Par.) With a Confirmed Response (CR, CCR, or PR) as Assessed by the MIRROR Panel
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
Duration of Response for All Confirmed Responders, Confirmed Complete Responders, and Confirmed Partial Responders
For all participants with CR, CCR, or PR, duration of response was defined as the time from first documented response to first documented progression. All confirmed responders included participants with CR, CCR, and PR, whereas confirmed complete responders included participants with CR and CCR.
MIRROR Panel Assessments of Duration of Complete Response (Time From the First Documented Response to the First Documented Progression)
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
MIRROR Panel Assessments of Duration of Confirmed Response (Time From the First Documented Response to the First Documented Progression)
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
Time to Progression of Disease or Death as Assessed by the Investigator
Progression-free survival or time to progression is defined as the time from the dosimetric dose to the first documented occurrence of disease progression or death.
Time to Progression of Disease or Death in Participants Before and After Crossover From Unlabeled TST to TST and Iodine I 131 TST as Assessed by the Investigator
Progression-free survival or time to progression is defined as the time from the dosimetric dose to the first documented occurrence of disease progression or death.
MIRROR Panel Assessed Time to Response (Time From the Date of Enrollment to the First Documented Response (PR, CR, CCR)
Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).
MIRROR Panel Assessed Progression-free Survival
Time from the date of enrollment (the date of randomization) to the first documented progression or death.
Overall Survival
Overall survival is defined as the time from the treatment start date to the date of death by any cause.
Number of Participants With the Indicated Drug-Related (DR) Adverse Events (AEs) Experienced by 3 or More Participants
An AE is any untoward medical occurrence in a participant administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. Causality of AEs was determined by the investigators as "none," "remote," "possible," "probable," or "highly probable." AEs considered by the investigator as being at least remotely related to the study treatment were considered to be DR AEs. White blood cell (WBC) count and absolute neutrophil count (ANC) were measured as cells per millimeters cubed (mm^3); hemoglobin was measured in grams per deciliter (g/dL).
Number of Participants With the Indicated Type of Infection
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. 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 indicate that the tested participant has the infection under investigation, in which case therapeutic treatment with anti-infective is required.
Number of Participants With an Infection for Which Anti-infectives Were Administered
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.
Number of Participants With the Indicated Grade 3 or Grade 4 AEs Experienced by 3 or More Participants
AEs 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.
Number of Participants With the Indicated Grade 3 or Grade 4 Drug-related AEs Experienced by 3 or More Participants
AEs 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.
Number of Participants With the Indicated Primary Cause of Death
Participants were categorized according to their primary cause of death. Deaths due to progressive disease or to another reason ("Other") were not captured as serious adverse events (SAEs) and are thus not included in the SAE module.
Number of Participants With a Time to Death From the Last Dose of Study Drug Less Than or Equal to 30 Days or More Than 30 Days
Time to death from the last dose of study drug is the time from the last dose of study drug administered to the date of death. Deaths due to progressive disease or to another reason ("Other") were not captured as serious adverse events (SAEs) and are thus not included in the SAE module.
Number of Participants With the Indicated Serious Adverse Events (SAE) Related to Study Drug
An SAE is any event occurring at any dose that results in any of the following: death, a life-threatening adverse drug experience (ADE; at immediate risk of death from the experience as it occurred), inpatient hospitalization/prolongation of existing hospitalization, a persistent/significant disability/incapacity, or a congenital anomaly/birth defect. Medical events that may not result in death, be life-threatening, or require hospitalization may be considered to be a serious ADEs when based upon appropriate medical judgment. Relatedness was based on the investigator's medical judgement.
Number of Participants With the Indicated Fatal SAEs Related to Study Drug
An SAE is any event occurring at any dose that results in any of the following: death, a life-threatening adverse drug experience (ADE; at immediate risk of death from the experience as it occurred), inpatient hospitalization/prolongation of existing hospitalization, a persistent/significant disability/incapacity, or a congenital anomaly/birth defect. Medical events that may not result in death, be life-threatening, or require hospitalization may be considered to be a serious ADEs when based upon appropriate medical judgment. Relatedness was based on the investigator's medical judgement.
Time to Nadir and Time to Recovery to Baseline in Hematologic Laboratory Evaluations
Nadir is defined as the lowest laboratory value recorded following the administration of the study medication. Time to recovery to baseline in hematologic laboratory evaluations is the time required for recovery from nadir values to baseline values. Hematologic laboratory evaluations included ANC, hemoglobin (Hb), platelets (Plt), and WBC count.
Nadir Values for ANC, a Hematologic Parameter
Nadir is defined as the lowest laboratory value recorded following the administration of study medication. ANC is a measure of the number of neutrophil granulocytes present in the blood. Neutrophils are a type of white blood cell that fights against infection.
Nadir Values for Hemoglobin, a Hematologic Parameter
Nadir is defined as the lowest laboratory value recorded following the administration of study medication. Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells.
Nadir Values for the Hematologic Parameters Platelets and WBC Count
Nadir is defined as the lowest laboratory value recorded following the administration of study medication. Platelets and WBCs are types of blood cells.
Number of Participants With the Indicated Grade 3 or Grade 4 Hematologic Toxicities
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.
Duration of the Indicated Grade 3 or Grade 4 Hematologic Toxicities
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.
Time to Human Anti-Murine Antibodies (HAMA) Positivity From the First Dosimetric Dose
Tositumomab is a murine (mouse) antibody (immunoglobulin) of the IgG2a subclass. Participants in this study were evaluated to determine whether they developed an immune response to study treatment as evident by human anti-mouse antibodies (HAMA) after administration of tositumomab and iodine I 131 tositumomab. A positive HAMA value indicates that the participant developed human anti-mouse antibodies above the HAMA assay threshold, and a negative HAMA value indicates either the absence or below threshold level of human anti-mouse antibodies.