ORM-1153 IND Clearance: Novel Mechanism, No Human Data, High Evidentiary Bar Ahead

FDA Clears IND for Orum's ORM-1153 in AML

Orum Therapeutics announced that the U.S. FDA has cleared its Investigational New Drug (IND) application for ORM-1153, a novel CD123-GSPT1 degrader-antibody conjugate (DAC). This clearance paves the way for a first-in-human Phase 1 study of ORM-1153, expected to begin by the end of 2026. The study will enroll approximately 42 patients with relapsed or refractory acute myeloid leukemia (AML) and other hematologic malignancies at U.S. clinical sites. ORM-1153 utilizes Orum’s TPD²® approach, combining cell-selective delivery with targeted protein degradation, aiming to improve treatment efficacy and tolerability for severe hematologic malignancies. Preclinical data presented at AACR 2026 demonstrated broad activity across AML models, including in primary patient samples and TP53-relevant models, with favorable tolerability.

• Orum Therapeutics achieved a significant regulatory milestone with the U.S. FDA clearance of its IND application for ORM-1153, a CD123-GSPT1 degrader-antibody conjugate. This approval allows the company to initiate a first-in-human Phase 1 clinical study, advancing its innovative degrader-antibody conjugate platform into clinical development.
• ORM-1153 leverages Orum’s proprietary Dual-Precision Targeted Protein Degradation (TPD²®) approach, which combines precise antibody-mediated cell delivery with targeted protein degradation. This mechanism specifically delivers a GSPT1 degrader payload to CD123-expressing cells, enabling the selective degradation of the intracellular GSPT1 protein, offering a highly targeted therapeutic strategy for cancer.
• Preclinical studies, presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, demonstrated ORM-1153's broad activity across various AML models, including primary AML patient samples and TP53-relevant models. The data also highlighted promising low-dose in vivo activity and favorable repeat-dose tolerability, suggesting potential for improved efficacy and safety in patients.
• The planned multicenter Phase 1 study will assess the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of ORM-1153. The trial is designed to initially enroll approximately 42 patients with relapsed or refractory acute myeloid leukemia and other hematologic malignancies at U.S. clinical sites, with potential for future expansion to other regions.

ORM-1153: A Novel CD123-GSPT1 DAC for AML

Recent AML research has expanded well beyond established targets, with several mechanistically distinct classes of agents advancing through clinical and preclinical development. Menin inhibitors have emerged as a particularly significant breakthrough, with revumenib receiving accelerated regulatory approval in November 2024 for relapsed/refractory KMT2A-rearranged leukemia. Next-generation menin inhibitors — including ziftomenib, bleximenib, enzomenib, and BMF-219 — have demonstrated composite complete remission rates of 20–35% and overall response rates of 45–65% in heavily pretreated patients. Triplet combinations incorporating these agents with intensive chemotherapy or venetoclax plus hypomethylating agents have yielded response rates exceeding 80% in de novo settings and 50–70% in relapsed disease, with the majority of responding patients achieving measurable residual disease negativity. On the epigenetic front, LSD1 (lysine demethylase 1) inhibition is also gaining traction; DC551040, a potent and selective irreversible LSD1 inhibitor, has shown encouraging tolerability in a Phase I AML trial (CTR20222026), while SP2509 has demonstrated the ability to promote differentiation of UTX-deficient hematopoietic stem and progenitor cells and extend survival in murine leukemia models.

Cell surface antigen targeting represents another rapidly evolving area of investigation, with multiple receptors under active exploration for immunotherapeutic applications. CLL-1 (C-type lectin-like molecule-1), stably expressed on AML blasts throughout disease progression but absent on normal hematopoietic stem cells, is being pursued across CAR-T-cell and antibody-drug conjugate (ADC) platforms and has potential utility in minimal residual disease monitoring. TIM-3, similarly expressed on leukemic stem cells and blasts in the majority of AML patients but not on normal hematopoietic stem cells, is being targeted by KK2845 — an ADC demonstrating cytotoxicity comparable to CD33-directed agents with a more favorable toxicity profile against normal bone marrow cells. Additional surface targets including CD33, CD123, CD7, CD70, CD38, and FLT3 are being investigated through immunoconjugates, bispecific T-cell engagers, and CAR-T constructs.

Resistance to venetoclax has accelerated interest in next-generation BCL-2 family inhibitors such as sonrotoclax, alongside strategies that address MCL-1 upregulation via cyclin-dependent kinase inhibition. Integrated approaches combining BCL-2 inhibition with immunotherapy have shown synergistic activity, with reported improvements in progression-free survival of 30–40%. PIM family serine/threonine kinases represent an additional co-therapeutic target of interest; PIM inhibitors have demonstrated synergy with splicing modulators targeting SF3B1 and SRPK1, as well as with RNA polymerase I inhibitors, resulting in enhanced AML cell killing and suppression of tumor growth in preclinical models.

The Persistent Challenges in Relapsed/Refractory AML

Relapsed/refractory AML remains one of oncology's most intractable clinical problems, characterized by a convergence of biological resistance mechanisms, therapeutic limitations, and patient-specific vulnerabilities. Current treatment approaches face challenges across multiple dimensions — from molecular resistance to transplant eligibility — that collectively constrain durable remission and long-term survival.

• Leukemic stem cell (LSC)-driven resistance and minimal residual disease (MRD): LSCs underpin both primary and acquired resistance through a multilayered network of intrinsic and extrinsic mechanisms, including cellular quiescence, enhanced multidrug efflux, apoptosis evasion, stress-adaptive autophagy, and epigenetic/metabolic plasticity. Protective bone marrow niche interactions further reinforce LSC survival under therapeutic pressure. Approximately half of adult patients achieving complete remission will relapse within 12 months due to outgrowth of residual disease, and MRD positivity in the bone marrow correlates directly with poor survival outcomes.

• Resistance to FLT3 inhibitors: Although agents such as midostaurin, gilteritinib, and quizartinib demonstrate strong initial response rates in FLT3-mutated AML, the durability of response is frequently insufficient. Secondary resistance emerges through both on-target mechanisms — including TKD mutations (e.g., D835Y) that maintain the kinase domain in its active conformation, and the universal resistance-conferring gatekeeper mutation F691L — and off-target mechanisms such as activating mutations in NRAS, AXL, and PIM1 that bypass or reinforce FLT3 signaling. Additionally, FL-dependent activation of co-expressed wild-type FLT3 and IFNγ-mediated STAT1/AXL upregulation within the bone marrow microenvironment further attenuate inhibitor efficacy.

• Venetoclax-based therapy resistance: Resistance to hypomethylating agent (HMA) and venetoclax (VEN) combinations has emerged as a significant and growing clinical challenge in myeloid malignancies. Prognosis following HMA/VEN failure remains poor, and strategies to overcome both primary and secondary resistance to this regimen represent a clear unmet clinical need.

• Barriers to allogeneic hematopoietic stem cell transplantation (HSCT) and post-transplant relapse: Patients proceeding to allogeneic HSCT are inherently a high-risk population, often presenting with advanced disease, elevated relapse risk, advanced age, and significant comorbidities. Patients aged ≥70 years have traditionally been excluded due to concerns over transplant-related mortality and post-transplant complication management. Even among those who do proceed, the cumulative incidence of relapse at 2 years in older AML patients receiving reduced-intensity conditioning HSCT reaches 44% (95% CI, 35%–53%), underscoring the inadequacy of current transplant strategies in this setting.

• Poor outcomes in older AML patients: Long-term survival rates for older patients with newly diagnosed AML are extremely low. Transplant eligibility assessments in this population must extend beyond disease risk stratification and treatment response to encompass comprehensive evaluation of comorbidities, functional status, cognitive function, and social support — adding complexity to treatment decision-making and limiting access to potentially curative approaches.