PRIMARY OBJECTIVE:~I. To assess the safety and tolerability of 111In/225Ac-DOTA-daratumumab, at each dose level in order to establish the maximum tolerated dose (MTD), which will inform the recommended phase 2 dose (RP2D).~SECONDARY OBJECTIVES:~I. To describe the anti-myeloma activity of 225Ac-DOTA-daratumumab as assessed by overall response rate (ORR).~II. To evaluate the organ biodistribution, pharmacokinetics and organ dose estimates of 111In/225Ac-DOTA-daratumumab.~EXPLORATORY OBJECTIVE:~I. To assess the activity of 225Ac-DOTA-daratumumab against non-cancer immune cells using the peripheral blood and bone marrow (BM) samples.~OUTLINE: This is a dose-escalation trial of 225Ac-DOTA-daratumumab.~Patients receive daratumumab intravenously (IV) over 45 minutes. Two hours later, patients receive 111In-DOTA-daratumumab and 225Ac-DOTA-daratumumab IV over 20-30 minutes.~After completion of study treatment, patients are followed up weekly for 8 weeks, every 2 weeks for 4 weeks, every 4 weeks for 16 weeks, and then periodically up to 12 months.
This phase I trial tests the safety, side effects, and best dose of actinium Ac 225-DOTA-daratumumab (225Ac-DOTA-daratumumab) in combination with daratumumab and indium In 111-DOTA-daratumumab (111In-DOTA-daratumumab) in treating patients with multiple myeloma that does not respond to treatment (refractory) or that has come back (recurrent). Daratumumab is a monoclonal antibody that may interfere with the ability of cancer cells to grow and spread. 111In-DOTA-daratumumab and 225Ac-DOTA-daratumumab are forms of radioimmunotherapy in which a monoclonal antibody, daratumumab, has been linked to a radiotracer to allow for targeted delivery of the treatment to cancer cells. Giving all three together may kill more cancer cells.