An adverse event (AE) was any medical occurrence in a participant who was administered denileukin diftitox and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), and did not necessarily have a causal relationship with this treatment. An AE included any side effect, injury, toxicity, sensitivity reaction, or any undesirable clinical or laboratory event that was not normally observed in the participant. Safety was assessed for all participants who received at least one dose of study medication and was monitored throughout the study. Safety evaluations were based on the incidence, intensity, and type of AE, and clinically significant changes in the participant's medical history, physical examination findings, vital signs, and clinical laboratory results. Participants also notified the study staff of any problems that occurred between visits by telephone, and if necessary, were evaluated by the investigator or study staff at an unscheduled interim visit.

The Safety Population was used and defined as all treated participants. Participants who did not receive at least one dose of study medication were excluded from this population. For this study, the safety population is the same as the Intent to Treat (ITT) population.

A treatment-related adverse event was any medical occurrence in a participant who was administered denileukin diftitox and CHOP and was determined to be possibly, probably, or definitely related to study treatment. An AE included any side effect, injury, toxicity, sensitivity reaction, or any undesirable clinical or laboratory event that was not normally observed in the participant. Safety was assessed for all participants who received at least one dose of study medication and was monitored throughout the study. Safety evaluations were based on the incidence, intensity, and type of AE, and clinically significant changes in the participant's medical history, physical examination findings, vital signs, and clinical laboratory results. Participants also notified the study staff of any problems that occurred between visits by telephone, and if necessary, were evaluated by the investigator or study staff at an unscheduled interim visit.

Safety population

Treatment-related AEs were medical occurrences determined to be possibly, probably, or definitely related to study treatment. Severity grading of the AE was according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) severity scale (grades 1 - 5) with grade 3 representing a severe AE. Safety was assessed for all participants who received at least one dose of study medication and was monitored throughout the study. Safety evaluations were based on the incidence, intensity, and type of AE, and clinically significant changes in the participant's medical history, physical examination findings, vital signs, and clinical laboratory results. Participants also notified the study staff of any problems that occurred between visits by telephone, and if necessary, were evaluated by the investigator or study staff at an unscheduled interim visit.

Safety population

A serious adverse event (SAE) was any AE that occurred at any dose and resulted in any of the following outcomes: death, a life-threatening adverse drug experience, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant disability/incapacity, or a congenital anomaly/birth defect. Important medical events that did not result in death, were life-threatening, or required hospitalization were considered a SAE when based upon appropriate medical judgment, jeopardized the participant and required medical or surgical intervention to prevent one of the outcomes listed above. Possibly Related (Poss Rel) applied to AEs judged to be perhaps related to study medication, Probably Related (Prob Rel) applied to AEs judged to have a high degree of certainty as related to study medication, and Definitely Related (Def Rel) related applied to AEs that were judged to be without a doubt related to study medication.

Safety population

Response rate was defined as the percentage of the ITT population who achieved a Complete Response (CR), Unconfirmed Complete Response (CRu), or Partial Response (PR). The International Working Group recommendations on non-Hodgkin's lymphoma response criteria were used to determine response to therapy. Largely, the protocol defined the response criteria as: 1) CR, loss of all detectable clinical and radiographic evidence of disease and disease-related symptoms if present before therapy; 2) CRu, CR with the caveats, response to therapy was accompanied with a 75% reduction in measurable lesion size and/or an indeterminate bone marrow biopsy (if initially positive); and 3) PR, less than or equal to 50% decrease in the sum of the measurements of tumor diameters, no increase in the size of other nodes, liver, or spleen, hepatic or spleen nodules regressed by at least 50%, and/or no new sites of disease.

Intent to treat (ITT) population included all participants who signed an informed consent and were deemed eligible to participate by the investigator based on the screening assessments, and started at least 1 cycle of study treatment. It is the same as the Safety Population (SP) for this study.

Response rate was defined as the percentage of the EA population who achieved a CR, CRu, or PR. The International Working Group recommendations on non-Hodgkin's lymphoma response criteria were used to determine response to therapy. Largely, the protocol defined the response criteria as: 1) CR, loss of all detectable clinical and radiographic evidence of disease and disease-related symptoms if present before therapy; 2) CRu, CR with the caveats, response to therapy was accompanied with a 75% reduction in measurable lesion size and/or an indeterminate bone marrow biopsy (if initially positive); and 3) PR, less than or equal to 50% decrease in the sum of the measurements of tumor diameters, no increase in the size of other nodes, liver, or spleen, hepatic or spleen nodules regressed by at least 50%, and/or no new sites of disease.

EA population includes all participants who received at least 2 cycles of study drug treatment, were eligible to participate or ineligible with an exception granted by the principal investigator (PI), had bidimensional lesions at baseline, and had at least 1 disease response assessment form submitted following cycle 2.

Duration of response was defined as the length of time from the first date at which the response criteria were met (taking the earliest date at which a PR, CRu, or the confirmed CR occurred) until the date that recurrent or PD or death was accurately documented, per the criteria defined for progression-free survival (PFS). All participants within the EA population who achieved a response per the criteria defined were included in the duration of the response analysis. Participants lost to follow-up prior to PD or death were censored at the date they were last known to still be responding to treatment. Duration of response was estimated using the Kaplan-Meier method with the median duration of response summarized.

EA population

PFS was defined as the period of time from treatment start to the first documentation of PD, recurrence, or death. PD was defined as a greater than or equal to 50% increase from baseline in the sum of the products of the greatest diameters of any previously identified abnormal node for PRs or non-responders, or the appearance of any new lesions during or at the end of therapy. PFS was censored at the last date for which the response assessment resulted in the absence of PD for participants who did not demonstrate objective progression or recurrence. Participants who withdrew prior to evidence of disease progression or recurrence, PFS was censored at the last date assessment showed an absence of PD.

ITT population

Overall Survival (OS) was defined as the time from the date of registration to the date of the participant's death. OS was determined by reviewing all participant's records every 6 months until the study was administratively closed or all participants died, whichever occurred first. Participants who were lost to follow-up but were still alive at the date of last contact were censored at the date of last contact. Participants who did not have a recorded date of death were censored for OS at the last date at which they were known to be alive.

ITT population