CD38 and autoimmune disease: In recent years, plasma-cell depletion with daratumumab, a monoclonal antibody against CD38, has been used successfully for treatment-resistant patients with various autoimmune diseases, including iTTP, although long-term data remain limited.<h4>Objectives</h4>To assess the efficacy, durability, and safety of daratumumab in patients with r/r iTTP.<h4>Methods</h4>We retrospectively analyzed 8 daratumumab treatment episodes in 5 patients with r/r iTTP, treated at 3 Swiss tertiary centers, with a median follow-up after daratumumab of 44 months (range, 34-65 months).