Orum Therapeutics Presents Preclinical Data at ASH 2025 Demonstrating Potent and Selective Antitumor Activity of ORM-1153, a CD123-Targeting Degrader Antibody Conjugate for Acute Myeloid Leukemia

BOSTON & DAEJEON, South Korea--(BUSINESS WIRE)--#ADC--Orum Therapeutics (“Orum” or the “Company”) (KRX: 475830), a public biotechnology company pioneering the field of degrader-antibody conjugates (DACs), today announced the presentation of preclinical data for ORM-1153 at the 67th American Society of Hematology (ASH) Annual Meeting, taking place December 6 to 9, 2025, in Orlando, Florida. ORM-1153 is a novel CD123-targeting DAC designed to deliver Orum’s proprietary GSPT1-degrading payload selectively into cancer cells to achieve targeted protein degradation and antitumor activity in acute myeloid leukemia (AML) and other CD123-positive hematological malignancies.

“These data highlight ORM-1153 as a differentiated therapeutic candidate designed to address the need for more effective and better-tolerated treatments for acute myeloid leukemia,” said Sung Joo (SJ) Lee, Ph.D., Founder and CEO of Orum Therapeutics. “AML remains one of the most challenging hematologic cancers to treat, with frequent relapse and limited options, particularly for patients with TP53-mutant disease. These data demonstrate the potential of ORM-1153 to achieve potent antitumor activity with a differentiated safety profile, addressing long-standing limitations of current AML therapies and further validating the versatility of our targeted protein degrader approach.”

The preclinical data presented at ASH show that ORM-1153 drives efficient, CD123-dependent internalization and degradation of GSPT1, resulting in strong and durable antitumor activity in AML models, including TP53-mutant disease. In comparative studies, ORM-1153 demonstrated approximately 1,000-fold higher potency than the unconjugated degrader payload and produced dose-dependent tumor regression in a disseminated AML xenograft model, with complete and durable responses at the highest dose level.

Importantly, ORM-1153 maintained a favorable tolerability profile and showed minimal effects on normal hematopoietic progenitors in colony-forming assays, suggesting potential for a differentiated therapeutic window compared with current standard-of-care. Together, these findings support ORM-1153 as a promising candidate for the treatment of AML and other CD123-positive hematologic malignancies.

About Orum’s TPD²® Approach

Orum’s unique Dual-Precision Targeted Protein Degradation (TPD²®) approach builds novel targeted protein degraders combined with the precise cell delivery mechanisms of antibodies to generate innovative, first-in-class, cell-selective TPDs for the treatment of cancer and other serious diseases. Orum has developed new targeted protein degrader payloads to specifically degrade an intracellular target protein within cancer cells via the E3 ubiquitin ligase pathway. Conjugated to antibodies, the payloads are designed to be delivered specifically to target cells and precisely degrade the intracellular target protein of interest.

About Orum Therapeutics

Orum Therapeutics is a public biotech pioneering the development of cell-specific, targeted protein degraders (TPD²®) with the precision of antibody targeting to develop the next generation of degrader antibody conjugates (DACs) for oncology and beyond. The company is advancing its GSPT1-directed TPD² programs and developing novel degrader payloads to expand the potential of targeted protein degradation. Orum's novel targeted protein degrader payloads are designed to selectively degrade key intracellular proteins, offering a highly targeted approach to treating difficult-to-treat diseases. Orum is located in Lexington, MA, US, and Daejeon, South Korea. For more info, visit www.orumrx.com.

Orum Therapeutics Forward-Looking Statements

This press release contains forward-looking statements that are based on the current expectations and beliefs of Orum Therapeutics, Inc. (“Orum”). Statements in this release regarding matters that are not historical facts, including, but not limited to, statements relating to the potential potency, tolerability, therapeutic window, and durable activity of ORM-1153; its advancement beyond the preclinical stage; its potential indications; and the potential versatility of Orum’s targeted protein degrader approach are forward-looking statements. These forward-looking statements are based on management’s expectations and assumptions as of the date of this release and are subject to numerous risks and uncertainties, which could cause actual results to differ materially from those expressed or implied by such statements. These risks and uncertainties include, without limitation, the uncertainty of success in research and development activities; competition from alternative therapies; and risks related to the recruitment and retention of key employees, fluctuating markets and economic conditions, and future fundraising. The forward-looking statements in this presentation speak only as of the date of this release, and Orum undertakes no obligation to update or revise any of the statements. Orum cautions investors not to place considerable reliance on the forward-looking statements contained in this release.

Corporate: IR/PR, Orum Therapeutics, media@orumrx.com
Media: Jessica Yingling, Ph.D., President, Little Dog Communications Inc., jessica@litldog.com