A DLT was defined as any treatment-related toxicity that was National Cancer Institute Common Terminology Criteria for Adverse Event Grade ≥3, confirmed by the safety monitoring committee to be relevant for the study drug treatment, and that occurred during the first 3 weeks of balstilimab treatment in the dose escalation portion of the study (DLT evaluation period).

An adverse event (AE) was any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product, which did not necessarily have a causal relationship with the treatment. TEAEs were AEs with onset dates during the on-treatment period, or the worsening of an event during the on-treatment period. A summary of all Serious Adverse Events and Other Adverse Events (nonserious), regardless of causality, is located in the 'Reported Adverse Events' Section.

ORR was defined as percentage of participants with a best overall response (BOR) of complete response (CR) or partial response (PR), as determined by an IERC per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). BOR was defined as the best response recorded from the start of the study treatment until the end of treatment. CR was defined as disappearance of all target lesions, and PR was defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters.