A Second Chance for a Targeted IBM Drug: New Funding Backs a Retry Focused on Earlier-Stage Disease
For people following IBM drug development, one question has loomed all year: would ulviprubart — an experimental antibody that targets the very immune cells thought to damage IBM muscle — get another chance? On August 18, 2026, Abcuro announced it had raised $66 million (a "Series D" financing round) to do exactly that. The company plans to launch a new Phase 3 trial focused on people with less severe IBM, with an eye toward seeking FDA approval if the study succeeds.
Why This Is a Big Deal
Ulviprubart (formerly ABC008) works differently from most experimental IBM drugs. Up to now, most therapies have tried to calm general inflammation. Ulviprubart instead targets a specific marker called KLRG1 found on a subset of highly activated "cytotoxic" T cells — the immune cells researchers believe are directly killing muscle fibers in IBM. By selectively depleting these cells while sparing the rest of the immune system, the drug aims to slow the muscle damage at its source.
Earlier this year, the company reported that its large Phase 2/3 "MUSCLE" study did not meet its main goal in the overall patient group. In 272 people with IBM, the low-dose group declined by 1.7 points on the IBM-FRS (a standard measure of function) over 76 weeks, the high-dose group by 2.1 points, and placebo by 2.4 points. Those differences were not statistically significant.
The encouraging part came from a pre-planned analysis of people who entered the study with less severe disease (an IBM-FRS score of 29 or higher). In that subgroup, both dose groups declined by about 50% more slowly than placebo — a difference the researchers called clinically meaningful even though it also did not reach conventional statistical significance.
Ulviprubart also looked safe and was generally well tolerated compared with placebo. Notably, no one receiving the drug stopped treatment because of a side effect, and nearly all participants who finished the study chose to continue into an ongoing open-label extension.
What the New Money Will Do
The $66 million round, led by New Leaf Venture Partners, will support a potentially "registrational" Phase 3 study — meaning its goal is to generate the evidence needed for approval. The trial is expected to begin in the fourth quarter of 2026 and to report top-line results in the second half of 2028. The company says it has been in discussion with the U.S. Food and Drug Administration about a path forward, and that, assuming positive results, it plans to file a biologics license application (BLA).
What This Means for IBM Patients
This is not a cure, and approval is still years away and far from guaranteed. But the decision to fund a second large trial is a meaningful signal. It shows that sophisticated investors and researchers believe targeting KLRG1-positive T cells — in the right patients, at the right stage of disease — is worth a carefully designed second experiment.
It also reflects a broader shift in the field: an increasing focus on testing treatments earlier in IBM, when muscle is less damaged, and a growing recognition that "earlier is better" may be key to showing a benefit. For patients, the number to watch is whether the new trial really does enroll people with less severe IBM and whether the promising trend from the MUSCLE subgroup holds up in a dedicated study.
Where to Learn More
For the community's perspective on this development, The Myositis Association published a summary on August 20, 2026 titled "New Hope on the Horizon." The company's press release (August 18, 2026), which includes the full investor list and quotes from the trial's principal investigator, is available from Abcuro and BioSpace. Anyone interested in participating in future trials should discuss eligibility with their neurologist or myositis specialist.
Source
• Abcuro, Inc. "Abcuro Announces $66 Million Series D Financing to Advance Its First-In-Class Medicine in Development for Inclusion Body Myositis." BioSpace, August 18, 2026. https://www.biospace.com/press-releases/abcuro-announces-66-million-series-d-financing-to-advance-its-first-in-class-medicine-in-development-for-inclusion-body-myositis
• Kobert L. "New Hope on the Horizon." The Myositis Association, August 20, 2026. https://www.myositis.org/blog/new-hope-on-the-horizon/
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