The purpose of this study is to determine the safety and tolerability in subjects who receive FF-21101(111In) for dosimetry and FF-21101(90Y) for treatment of advanced solid tumors.

The purpose of this study is to determine the safety and tolerability in subjects who receive FF-21101(111In) for dosimetry and FF-21101(90Y) for treatment of advanced solid tumors. This is an open label study that will recruit approx 70 patients

Inclusion Criteria:

• Males and females ≥ 18 years of age
• Histologically or cytologically confirmed advanced solid tumor malignancy, refractory or relapsed from prior therapy, or for whom no alternative therapy is available
• At least 4 weeks beyond the last chemotherapy (or ≥ 5 half-lives for targeted agents, whichever is shorter), radiotherapy, major surgery or experimental treatment and recovered from all acute toxicities (≤ Grade 1)
• Archival tumor sample available, or be willing to undergo a fresh tumor biopsy, prior to study
• At least one measurable disease site that meets target lesion requirements
• Adequate performance status: Eastern Cooperative Oncology Group (ECOG) ≤ 2
• Life expectancy of ≥ 3 months
• Adequate hematologic parameters without ongoing transfusional support:
• Negative serum pregnancy test
• Ability to provide written informed consent

Exclusion Criteria:

• Previous radioimmunotherapy. Previous antibody-based therapy is allowed as long as ≥ 28 days has elapsed from last dose to study treatment.
• Prior radiation to > 30% of the red marrow or to maximal tolerable level for any organ
• Serious cardiac condition within the last 6 months
• Concomitant medication(s) that may cause QTc prolongation or induce Torsades de Pointes, with the exception of antimicrobials that are considered to be essential for care of the patient
• History of retinal degenerative disease, history of uveitis, history of retinal vein occlusion (RVO), or any eye condition that would be considered a risk factor for RVO or has medically relevant abnormalities identified on screening ophthalmologic examination
• Active central nervous system (CNS) malignant disease in subjects with a history of CNS malignancy. Subjects with stable, prior, or currently treated brain metastases are allowed.
• Known positive for human immunodeficiency virus (HIV), hepatitis B virus surface antigen (HBsAg) or hepatitis C virus (HCV)
• Known autoimmune disease
• Active infection requiring intravenous (IV) antibiotic usage within the last week prior to the dosimetry portion of the study
• Corticosteroid use within 2 weeks of study treatment
• Any other medical intervention or other condition which, in the opinion of the Principal Investigator, could compromise adherence with study requirements or confound the interpretation of study results
• Pregnant or breast-feeding