South Korea and US-based Orum Therapeutics (KOSDAQ: 475830) received US FDA clearance to take ORM-1153, a degrader-antibody conjugate (DAC) designed to selectively deliver a GSPT1 degrader to CD123-expressing cancer cells, into clinical testing. The company plans to start a first-in-human Phase I trial in relapsed or refractory acute myeloid leukemia (AML) and other hematologic malignancies before the end of 2026.
ORM-1153 uses Orum's TPD² targeted protein degradation platform, combining an anti-CD123 antibody with a proprietary GSPT1-degrading payload through a cleavable β-glucuronide linker. The antibody is designed to internalize after binding CD123, allowing the payload to be released inside target cells and trigger degradation of GSPT1, a protein implicated in cell survival. The approach is intended to restrict exposure to the degrader through antibody-directed delivery rather than relying on a conventional cytotoxic ADC payload.
Preclinical data presented at the AACR 2026 Annual Meeting showed activity across primary AML patient samples and models relevant to TP53-mutant disease. Orum also reported low-dose in vivo activity, prolonged tumor accumulation, undetectable systemic free payload, and favorable findings in repeat-dose non-human primate studies. The candidate incorporates an antibody engineered for increased internalization and reduced Fc-gamma receptor interactions alongside a linker optimized for plasma stability.
The planned multicenter Phase I study is expected to initially enroll approximately 42 patients at US sites, with potential expansion to other regions. The trial will assess safety and tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity in relapsed or refractory AML and other hematologic malignancies.