Abcuro's Ulviprubart Misses Primary Endpoints in Inclusion Body Myositis Trial, Shows Promise in Mild-to-Moderate Patients
核心洞察
Abcuro (搜索)'s Phase 2/3 MUSCLE study of ulviprubart failed to meet primary and key secondary endpoints in the overall population of 272 inclusion body myositis (搜索) patients at Week 76.
Pre-specified subgroup analysis revealed clinically meaningful improvements in patients with mild to moderate disease, suggesting potential disease-modifying activity in this population segment.
The investigational monoclonal antibody demonstrated a favorable safety and tolerability profile compared to placebo, with no safety signals identified at the studied doses.
Abcuro (搜索) announced disappointing topline results from its Phase 2/3 MUSCLE clinical study of ulviprubart (ABC008), an investigational monoclonal antibody for inclusion body myositis (搜索) (IBM (搜索)), after the trial failed to meet its primary endpoint. However, the company found encouragement in subgroup analyses showing clinically meaningful benefits in patients with mild to moderate disease, establishing a potential pathway forward for this first-in-class therapeutic approach.
The global MUSCLE study (NCT05721573) enrolled 272 patients with IBM (搜索), randomized across two drug levels and placebo cohorts. The primary endpoint assessed changes in the IBM Functional Rating Scale (IBMFRS) total score at Week 76 compared to placebo, while key secondary endpoints included Manual Muscle Test 12 (MMT-12) and dynamometry measurements for hand grip and quadricep strength.
Subgroup Analysis Reveals Therapeutic Potential
While the overall study population did not achieve statistical significance, a pre-specified subgroup analysis in patients with mild to moderate disease at baseline demonstrated trends in improvement in the IBMFRS total score and key secondary endpoints. This finding suggests ulviprubart's potential disease-modifying activity in patients with less severe disease progression.
"While we are disappointed that the MUSCLE trial did not reach statistical significance in the overall study population, we are encouraged by the clear and meaningful magnitude of improvements observed in patients with mild to moderate disease, as well as its favorable safety and tolerability profile overall," said H. Jeffrey Wilkins, Chief Medical Officer of Abcuro (搜索).
Novel Mechanism Targets Disease Pathology
Ulviprubart represents a potential first-in-class monoclonal antibody designed to target pathogenic T cells expressing killer cell lectin-like receptor G1 (搜索) (KLRG1 (搜索)) on their cell surface. The drug selectively targets and depletes well-differentiated cytotoxic KLRG1+ T cells while sparing other immune cells, potentially offering improved safety and tolerability compared to other T cell depleting approaches.
"Ulviprubart was designed to target cytotoxic T-cells expressing KLRG1 (搜索), a pathology we believe is a potential driver of muscle destruction in IBM (搜索). This is the first study to investigate this mechanism of action in IBM," Wilkins explained.
Safety Profile Supports Continued Development
The study demonstrated ulviprubart's favorable safety and tolerability profile compared to placebo, with no safety signals identified at the doses studied. Nearly all patients who completed the MUSCLE study are currently receiving treatment in an ongoing open-label extension study.
Abcuro (搜索) plans to discuss its regulatory approach with the FDA in the near future and remains committed to advancing ulviprubart development for IBM (搜索) patients. The company will present detailed study results at the 6th Global Conference on Myositis meeting in Lisbon, Portugal, from March 23-26, 2026.
Addressing Significant Unmet Medical Need
IBM (搜索) represents a rare, debilitating and relentlessly progressive chronic autoimmune muscle disease with no approved pharmacologic treatments. The condition is mediated by highly differentiated T cells that are chronically or aberrantly overstimulated, leading to destruction of healthy muscle tissue. Patients progressively lose muscle function, including grip strength, dexterity and mobility.
Based on published epidemiology literature and diagnostic coding data, Abcuro (搜索) estimates approximately 40,000 patients with IBM (搜索) in the United States, with an additional 35,000 patients across major European countries and Japan.
"Abcuro (搜索) remains committed to the IBM (搜索) community, and we are extremely grateful to the clinical study participants, investigators, and study site teams that supported this important clinical study," said Alex Martin, Chief Executive Officer of Abcuro. "With insights derived from this study, we hope to continue developing ulviprubart for patients with IBM."