A Study of Olaratumab (IMC-3G3) in Prostate Cancer

PFS is measured from randomization to the earliest date of the following events: PD according to Response Evaluation Criteria In Solid Tumors (RECIST) criteria version (v) 1.1, is a ≥20% increase in the sum of diameter of the target lesions taking as reference the smallest sum on study and an absolute increase in the sum diameter of ≥5 millimeter (mm), the appearance of 1 or more new lesions and/or unequivocal progression of existing nontarget lesions, unequivocal evidence of progression by bone scan, clinical progression or death from any cause. For participants who had no documented PD or death or had started new anti-cancer therapy or were lost to follow-up, PFS was censored at their last tumor assessment.

OS was defined as the time from the date of randomization to the date of death from any cause. If the participants were alive at the end of the follow-up period or were lost to follow-up, OS time was censored on the last date the participant was known to be alive.

Best response is categorized using the RECIST v1.1 guidelines. CR is the disappearance of all non-nodal target lesions, with the short axes of any target lymph nodes reduced to <10 mm. PR is a ≥30% decrease in the sum of the diameters of target lesions (including the short axes of any target lymph nodes), taking as reference the pretreatment sum diameter. Percentage of participants = (number of participants who had CR or PR) / (number of participants treated) * 100.

Decrease in PSA ≥50% from pretreatment required confirmation no less than 3 weeks after the initial suggestion of response and occurring prior to documentation of PD. Percentage of participants = (number of participants who had ≥50% decrease in PSA at any time) / (number of participants treated) * 100.

Percentage of participants = (number of participants who had ≥30% decrease in PSA at Week 12) / (number of participants treated) * 100.

Data presented are the number of participants who experienced serious adverse events (SAEs) and other nonserious adverse events (AEs). For participants in mitoxantrone group who had PD and chose optional IMC-3G3 follow-on treatment, the baseline was defined as the last assessment prior to the start of the olaratumab treatment. A summary of SAEs and other nonserious AEs, regardless of causality, is located in the Reported Adverse Events section.

High expression (HE) of CTC was defined as having CTC counts ≥5 cells/7.5 milliliter (mL) and low expression (LE) of CTC was defined as having CTC counts <5 cells/7.5 mL. PFS is measured from randomization to the earliest date of the following events: PD according to RECIST criteria v. 1.1, is a ≥20% increase in the sum diameter of the target lesions taking as reference the smallest sum on study and an absolute increase in the sum diameter of ≥5 mm, the appearance of 1 or more new lesions and/or unequivocal progression of existing nontarget lesions, unequivocal evidence of progression by bone scan, clinical progression or death from any cause.

HE of CTC was defined as having CTC counts ≥5 cells/7.5 mL and LE of CTC was defined as having CTC counts <5 cells/7.5 mL. OS was defined as the time from the date of randomization to the date of death from any cause.

PDGFRα protein expression (pretreatment) by IHC was assessed in tumor cells, and was provided as a dichotomous variable with "positive" and "negative" expression. "Positive" corresponds to weak intensity membranous staining comprising greater than 30% of the tumor and/or moderate to strong intensity membranous staining comprising greater than 5% of the tumor. "Negative" corresponds to staining that does not meet these requirements.

Participants with Treatment Emergent (TE) anti-olaratumab antibodies were participants with a 4-fold increase (2 dilutions) increase over a positive baseline antibody titer or for a negative baseline titer, a participant with an increase from the baseline to a level of 1:20.