Number of participants with PFS responders and non-responders at Month 6 was reported. PFS was defined as the time from the date of the first dose of amatuximab to the date of disease progression or death due to any cause, as determined by independent radiologist based on the modified Response Evaluation Criteria in Solid Tumors (RECIST) utilizing the total tumor measurement (performed by computerized tomography (CT)/magnetic resonance imaging (MRI)) which includes the pleural unidimensional measure plus the total of the target lesion(s) measurement. A "response", in terms of PFS, was defined to be at least a 6-month stabilization of disease. Progressive disease (PD) as measured by Modified RECIST was defined as an increase of at least 20 percent (%) in the total tumor measurement over the nadir measurement, or the appearance of one or more new lesions.

Primary Efficacy Population: all participants who received at least 1 dose of amatuximab and met key eligibility criteria (had measurable disease at screening, had unresectable disease, and had at least 1 response assessment or died after starting treatment with amatuximab). Here, number of participants analyzed are first 77 enrolled participants.

ORR, defined as the percentage of participants with objective evidence of complete response (CR) or partial response (PR) as determined by independent radiologist based on the modified RECIST utilizing the total tumor measurement (performed by CT/ MRI) which includes the pleural unidimensional measure plus the total of the target lesion(s) measurement. Tumor assessments performed up to the initiation of further anticancer therapy were considered. CR was defined as the disappearance of all target lesions with no evidence of tumor elsewhere, and PR was defined as at least a 30% reduction in the total tumor measurement. A confirmed response required a repeat observation on two occasions 4 weeks apart. ORR = CR + PR.

Primary Efficacy Population: all participants who received at least 1 dose of amatuximab and met key eligibility criteria (had measurable disease at screening, had unresectable disease, and had at least 1 response assessment or died after starting treatment with amatuximab).

DR was derived for those participants who achieved a PFS Response and had an objective evidence of CR or PR. DR was defined as the time (in months) from first documentation of objective response (CR or PR) to the first documentation of disease progression or death [as determined by independent radiologist based on the modified RECIST utilizing the total tumor measurement (performed by CT/ MRI) which includes the pleural unidimensional measure plus the total of the target lesion(s) measurement]. Tumor assessments performed up to the initiation of further anticancer therapy were considered. CR was defined as the disappearance of all target lesions with no evidence of tumor elsewhere, and PR was defined as at least a 30% reduction in the total tumor measurement. PD as measured by Modified RECIST was defined as an increase of at least 20% in the total tumor measurement over the nadir measurement, or the appearance of one or more new lesions.

Primary Efficacy Population: all participants who received at least 1 dose of amatuximab, met key eligibility criteria (had measurable disease at screening, had unresectable disease, and had at least 1 response assessment or died after starting treatment with amatuximab). Here, number of participants analysed included responders (CR or PR).

TTR was derived for those participants with objective evidence of CR or PR. TTR was defined as the time from the date of the first dose of amatuximab to first documentation of objective tumor response. CR was defined as the disappearance of all target lesions with no evidence of tumor elsewhere, and PR was defined as at least a 30% reduction in the total tumor measurement.

Primary Efficacy Population: all participants who received at least 1 dose of amatuximab and met key eligibility criteria (had measurable disease at screening, had unresectable disease, and had at least 1 response assessment or died after starting treatment with amatuximab). Here, number of participants analysed included responders (CR or PR).

OS was defined as the time from the date of the first dose of amatuximab to the date of death.

Safety population consisted of all participants who received at least 1 dose of amatuximab.

Overall PFS was defined as the time from the date of first dose of amatuximab to the date of disease progression or death due to any cause. In the absence of confirmation of death, the survival time was censored at the date of the last follow-up contact. Tumor assessments performed up to the initiation of further anticancer therapy were considered. PD as measured by Modified RECIST was defined as an increase of at least 20% in the total tumor measurement over the nadir measurement, or the appearance of one or more new lesions.

Primary Efficacy Population: all participants who received at least 1 dose of amatuximab and met key eligibility criteria (had measurable disease at screening, had unresectable disease, and had at least 1 response assessment or died after starting treatment with amatuximab).

An adverse event (AE) was any untoward medical occurrence (example; any unfavorable and unintended sign including abnormal laboratory findings, symptom or disease) in a participant or clinical investigation participant after providing written informed consent for participation in the study until the end of study visit. TEAEs were defined as an AE that developed or worsened in severity during the on-treatment period (from first dose of amatuximab to 30 days after last dose of amatuximab). SAE was defined as any adverse event (appearance of [or worsening of any pre-existing]) undesirable sign, symptom or medical conditions which is fatal or life-threatening or results in persistent or significant disability/incapacity or constitutes a congenital anomaly/birth defect or requires inpatient hospitalization or prolongation of existing hospitalization or is medically significant.

Safety population included all participants who received at least 1 dose of amatuximab.