The study is a sequential cohort ascending dose (3+3 methodology after a sentinel at the 0,25 mg/kg level) study to confirm safety and identify DLTs in the study population and determine the maximum tolerated dose (MTD) and the RP2D.~The range of proposed doses includes optimal doses identified in parallel safety studies of STI-6129 for the treatment of relapsed/refractory systemic amyloid light chain (AL) amyloidosis that are currently ongoing (a three-stage, multicenter, open-label, dose -finding, Phase 1 trial to identify the RP2D). STI-6129 will be given as an intravenous (IV) infusion.~Each patient enrolled will received repeated 4-week cycles of STI-6129 (Q4W) Total duration will vary according to patient response. After the treatment period, patients will be monitored for up to 2 years.
This study is a Phase 1b, single-center, open-label, dose-finding trial designed to identify the Recommended Phase 2 Dose (RP2D) of STI 6129 by assessing the safety, preliminary efficacy, and immunogenicity in subjects with any advanced solid tumor.~The patients that will be treated with STI-6129 in this trial are advanced solid tumor patients who have received prior lines of treatment.