The trial is a phase 1b open-label study of daratumumab in participants with APS.~The study design is a modification of the 3 + 3 dose escalation scheme. Three daratumumab dose cohorts are planned: 4 mg/kg, 8 mg/kg, and 16 mg/kg of intravenous (IV) daratumumab administered weekly for 8 doses (weeks 0 through 7). Post-treatment follow-up visits will occur at weeks 9, 12, 18, 24, 36, and 48.~Dose Escalation Phase Dose escalation will proceed according to safety criteria (Dose Limiting Toxicity, DLT) and efficacy criteria (antiphospholipid antibody negativity). An independent safety committee will review the data and approve escalation to the next dose.~The Highest Safe Dose (HSD) is the highest administered dose at which ≤ 1/6 participants experiences a DLT at or prior to week 9.~Expansion Phase Four additional participants will be enrolled and treated at the HSD weekly for 8 doses.
The purpose of this study is to see if the study medication, daratumumab, is safe to treat individuals with Anti-Phospholipid Syndrome (APS).~Three daratumumab dosing cohorts are planned with up to six participants in each dosing cohort with the potential to enroll an additional 4 subjects in the highest safe dose (HSD) cohort, for a total of up to 22 participants. The dosing cohorts are: 4 mg/kg, 8 mg/kg, and 16 mg/kg. Each cohort will receive intravenous (IV) administration of daratumumab according to the following schedule, for a total of 8 doses.~The primary objective is to determine the safety of daratumumab in APS defined as Dose Limiting Toxicities (DLTs) occurring during the dose escalation phase.