The study drug will be given by intravenous infusion once weekly as long as the subject is deriving clinical benefit until disease progression or other treatment discontinuation criteria met, unacceptable toxicity, or subject's refusal, whichever occurs first. The dose-limiting toxicity observation period will be 28 days, reflecting adequate exposure for safety assessment. The dose-escalation scheme will follow a Bayesian logistic regression model. A safety review committee will monitor safety and recommend all cohort dosing decisions. The starting First In Human dose for AFM28 will be 25 mg i.v. and treatment in each cohort will utilize a staggered approach, with at least 7 days between the first dose of the first subject and the first dose of subsequent subjects. In order to gather additional Pharmacokinetics/ Pharmacodynamics and safety data to inform potential final dose escalation decisions and selection of one or more recommended phase 2 doses at selected dose levels, additional subjects may be enrolled in at least two cohorts consistent with backfilling a cohort (up to 12 subjects).
This study is a First In Human, phase 1, open-label, non-randomized, multi-center, multiple ascending dose escalation study evaluating AFM28 as a monotherapy in subjects with Relapsed/Refractory CD123-positive Acute Myeloid Leukemia (AML). AFM28 is a tetravalent monoclonal antibody targeting the interleukin-3 receptor subunit alpha (IL3RA, CD123) and the low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A, CD16A). It is developed as an antineoplastic agent for hematologic malignancies known to express CD123. The primary pharmacological Mode of Action of AFM28 is induction of cell death of CD123-expressing cells by stimulating Antibody-Dependent Cell-mediated Cytotoxicity mediated by CD16A-expressing immune cells, primarily Natural Killer cells. The aim of the dose escalation is to determine the Maximum Tolerated Dose (MTD) and/or establish one or more Recommended Phase 2 Doses, based on safety, preliminary anti-leukemic activity and Pharmacokinetics / Pharmacodynamics data.