A Phase I Imaging and Pharmacodynamic Trial of CS-1008 in Patients With Metastatic Colorectal Cancer

Eligible subjects were to be enrolled into one of 5 dose-escalation cohorts to receive CS-1008 administered weekly as an intravenous (IV) infusion over 30 ± 10 minutes. Each cohort initially comprised 2 subjects but was expanded in up to 5 subjects if additional biodistribution and/or PK data were required. The initial infusion of CS-1008 on Day 1 was trace labeled with Indium-111 (111\^In-CS-1008; 5-7 mCi) and was investigated at escalating doses up to the standard loading dose, as follows: Cohort 1 (0.2 mg/kg), Cohort 2 (1 mg/kg), Cohort 3 (2 mg/kg), Cohort 4 (4 mg/kg), and Cohort 5 (6 mg/kg). The initial 111\^In-CS-1008 dose was followed by gamma camera imaging with blood sampling over a 10-day period to evaluate biodistribution, tumor uptake, PK, and serum biomarkers. Day 8 dosing comprised non-labeled CS-1008 at doses of 6 mg/kg in Cohorts 1-3, 4 mg/kg in Cohort 4, and 2 mg/kg in Cohort 5. Subsequent weekly infusions of standard dose CS-1008 (2 mg/kg) were administered on Days 15, 22, 29, 36, and 43. The Day 36 infusion of CS-1008 was also trace labeled with 111\^In (5-7 mCi), with subsequent gamma camera imaging and blood sampling. Subjects were assessed for disease status using the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, serum tumor biomarkers (carcinoembryonic antigen \[CEA\]), and human-anti-CS-1008-antibody development (HAHA). Subjects were assessed for changes in tumor metabolism following CS-1008 administration using computed tomography (CT) or fluorodeoxyglucose positron emission tomography (18\^F-FDG PET) scans. Cycle 1 encompassed the first 7 weeks of therapy. Within 1 week (Days 44-50) after the last infusion of CS-1008, subjects completed an End of Study/End of Cycle 1 assessment. Subjects with stable disease or better (according to RECIST version 1.1) at the Day 44-50 reassessment were permitted to receive additional 4-week cycles of CS-1008 (2 mg/kg) until disease progression, unacceptable toxicity, or subject/physician decision.