ORR was defined as the percentage of participants who had a confirmed complete response (CR) or partial response (PR) as per Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1. CR. CR was defined as the disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 millimeter (mm) (<1 centimeter [cm]). PR was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum diameters.

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment.

ORR was defined as the percentage of participants who had a confirmed CR or PR as per RECIST v1.1. CR was defined as the disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 mm (<1 cm). PR was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum diameters.

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment.

ORR was defined as the percentage of participants who had a confirmed CR or PR assessed by the investigator as per modified RECIST (mRECIST) v1.1. CR. CR was defined as the disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 mm (<1 cm). PR was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum diameters.

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment.

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An SAE was any AE that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect or was an important medical event. TEAEs were defined as AEs that developed, worsened (according to the investigator's opinion) or became serious during the TE period.

The exposed population consisted of all participants who had given their informed consent and received at least one dose of study treatment (pegenzileukin or other anticancer therapies).

Selected events that occurred during DLT observation period were considered as DLT unless due to PD or to a cause obviously unrelated to pegenzileukin. Selected events included: grade (G) 4 neutropenia for >=7 consecutive days, G3 or 4 neutropenia complicated by fever or microbiologically or radiographically documented infection, G3 or 4 thrombocytopenia associated with clinically significant bleeding that required clinical intervention; G3 or above alanine aminotransferase or aspartate aminotransferase in combination with a bilirubin >2 times upper limit of normal with no evidence of cholestasis or another cause such as viral infection or other drugs;G3 or above vascular leak syndrome, hypotension, and cytokine release syndrome;any other G3; G3 or 4 non-hematologic laboratory value; any death not clearly due to the underlying disease or extraneous causes;any toxicity that required permanent discontinuation of the study treatment(s).

The DLT-evaluable population consisted of all exposed participants in the safety run-in who had been observed for at least 21 days. Any participants who had experienced a DLT during DLT observation period were also DLT-evaluable.

TTR was defined as the time from the date of first study treatment administration to the first tumor assessment at which the overall response was recorded as PR or CR that was subsequently confirmed as per RECIST v 1.1 (NSCLC) and assessed by the investigator as per mRECIST v1.1 (mesothelioma). CR was defined as the disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 mm (<1 cm). PR was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum diameters.

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment. Only participants with confirmed CR or PR were analyzed.

DOR was defined as time from date of first tumor assessment at which overall response was recorded as CR or PR that was subsequently confirmed to date of first documentation of objective PD before initiation of any post-treatment anti-cancer therapy or death due to any cause, whichever occurred first, as per RECIST v 1.1 (NSCLS) and assessed by investigator as per mRECIST v1.1 (mesothelioma). CR: disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 mm (<1 cm). PR: at least a 30% decrease in sum of diameters of target lesions, taking as reference baseline sum diameters. PD:at least a 20% increase in sum of diameters of target lesions, taking as reference the smallest sum on study (this included baseline sum if that was smallest on study), in addition to relative increase of 20%, sum must have also demonstrated an absolute increase of at least 5 mm (0.5 cm).

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment. Only participants with confirmed CR or PR were analyzed.

The CBR was defined as the percentage of participants with clinical benefit: confirmed CR or PR as best overall response (BOR), or stable disease (SD) that lasted at least 6 months as per RECIST v 1.1 (NSCLS) and assessed by investigator as per mRECIST v1.1 (mesothelioma). CR: disappearance of all target lesions, any pathological lymph nodes (whether target or non-target) with reduction in short axis to <10 mm (<1 cm). PR: at least a 30% decrease in sum of diameters of target lesions, taking as reference baseline sum diameters. BOR was the best response observed from start of the study treatment until PD, death, cut-off date or initiation of post-treatment anticancer therapy, whichever occurred first. SD was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study.

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment.

The PFS was defined as the time from the date of first study treatment to the date of the first documentation of objective PD, or death due to any cause, whichever occurred first as per RECIST v 1.1 (NSCLS) and assessed by investigator as per mRECIST v1.1 (mesothelioma). PD was defined as at least a 20% increase in the sum of the diameters of target lesions, taking as reference the smallest sum on study (this included the baseline sum if that was the smallest on study), in addition to the relative increase of 20%, the sum must have also demonstrated an absolute increase of at least 5 mm (0.5 cm).

The efficacy population consisted of all participants from the exposed population with at least one evaluable post-baseline tumor assessment or who permanently discontinued study treatment.

Blood samples were collected at specified timepoints for the assessment of plasma concentrations of pegenzileukin. The pharmacokinetic (PK) parameters were calculated using non-compartmental method.

The PK population consisted of all participants from exposed population with at least one PK concentration available after the first dose of study treatment. Only participants with data collected at specified timepoints are reported. Limited or no participants returned on the Cycle 1 Day 3 for sample collection.

Blood samples were collected at specified timepoints for the assessment of Ceoi of pegenzileukin.

The PK population consisted of all participants from exposed population with at least 1 PK concentration available after the first dose of study treatment. Only participants with data collected at specified timepoints are reported. Eventually, the participants discontinued as they progressed in the study. Hence, fewer participants at each cycle and no participants returned on Cycle 15 in Cohort B1 Arm.

Blood samples were collected at specified timepoints to assess the presence of ADAs against pegenzileukin. Treatment-emergent ADA was defined as at least one treatment-induced or treatment-boosted ADA. Treatment-induced ADA was defined as ADA that developed during the TE period and without pre-existing ADA (including participants without pre-treatment samples). Treatment-boosted ADA was defined as pre-existing ADA that was boosted during the TE period to a significant higher titer than the baseline. Number of participants with treatment-emergent ADA is presented.

The ADA population consisted of all participants from the exposed population with at least one ADA result (positive, negative or inconclusive) after the first dose of study treatment.