Inclusion Body Myositis – Clinical Trials

Clinical trials for inclusion body myositis are research studies that investigate the effectiveness of new treatments, medical tests, or devices. Trials are carefully designed and follow strict procedures to help provide reliable results.

Clinical Trials - General Considerations

Phase I: Initial studies of new drugs in humans are small, short studies designed primarily to see if the medication is safe.
Phase II: If a medication seems safe, a larger and longer study will be done to begin to learn if the drug actually works, and to obtain more safety data. Sometimes studies are designated as either Phase IIa or Phase IIb. Phase IIa studies are more exploratory in nature. Although they are designed to reveal information about the efficacy of the drug, the primary endpoint may be to determine the optimal frequency of dosing, the type of patient most suitable for future testing, or other aspects of safety and efficacy. Phase IIb studies are more advanced, and are generally designed with efficacy as the primary endpoint.
Phase III: The final phase involves research studies of large groups of patients.

Each trial has eligibility criteria that specify which patients are allowed to participate. This can be frustrating if you are a patient who does not meet the criteria, especially for diseases like inclusion body myositis that do not have currently approved treatments. The purpose of the criteria is to ensure that all the patients in the trial have the same disease, and that they can participate in all aspects of the treatment and testing. This increases the likelihood that a successful treatment will be identified. If the treatment eventually does receive FDA approval, the treatment might then be given to patients who did not meet the eligibility criteria for the study.

Clinical trials for Rare Diseases are Challenging

It can be difficult to recruit adequate numbers of patients.
Clinical trials are expensive, and funding can be hard to obtain.
The natural history of the disease may be poorly known.

Natural History Studies

The natural history of a chronic disease refers to how the disease affects people, from the time the disease begins until the patient dies, without treatment. Accurate knowledge of how the disease progresses is crucial to the design and implementation of clinical trials. How do you test if a drug works if you don’t know what happens in the disease without the drug? Cure IBM encourages all inclusion body myositis patients to participate in natural history studies.

The INSPIRE-IBM study is a large natural history study that is currently underway. Study sites are located throughout the United States. Please visit the ClinicalTrials.gov webpage for more information.

The ClinicalTrials.gov online registry

ClinicalTrials.gov is an online registry of clinical trials, and is the place to go if you would like to search for clinical trials for inclusion body myositis. The site is managed by the United States National Library of Medicine and the National Institutes of Health. Although it is a US government website, some studies offered outside the United States are listed on the website. After entering inclusion body myositis as the name of the condition/disease, clicking the “Search all studies” button will bring up a list not only of active studies that are currently recruiting new patients, but also recently concluded studies and studies which are about to begin.

Inclusion Body Myositis Clinical Trials of Current Interest

Ulviprubart

Ulviprubart (ABC008) is an experimental treatment designed to reduce the immune-system attack on muscle that is believed to contribute to inclusion body myositis. It selectively removes a group of immune cells thought to be especially involved in damaging muscle, while leaving many other important immune cells intact.

More specifically, ulviprubart targets highly cytotoxic T cells that carry a marker called KLRG1. These KLRG1-positive T cells are found attacking muscle fibers in IBM. Ulviprubart is designed to selectively deplete these cells while preserving other T cells that perform important immune functions.

Abcuro's Phase 2/3 MUSCLE trial of ulviprubart did not meet its primary endpoint or key secondary endpoints in the overall study population. However, more detailed results showed an encouraging finding in a pre-specified group of patients with less severe IBM. In patients who entered the trial with an IBM Functional Rating Scale (IBMFRS) score of 29 or higher, both ulviprubart dose groups declined by 1.3 IBMFRS points over 76 weeks, compared with 2.6 points for placebo—a 50% slowing in functional decline relative to placebo.

In August 2026, Abcuro announced that it had raised $66 million to initiate a new Phase 3 study of ulviprubart in people with less severe IBM. The company plans to begin the study in 2026 and says it has alignment with the FDA on a path forward for the new trial.

The new Phase 3 trial will focus on people with less advanced IBM, the group in whom the earlier trial showed the strongest evidence of slowing disease progression. Details of the new study, including its eligibility requirements, have not yet been announced.

More information about the upcoming Phase 3 trial

More information about the ulviprubart clinical trial

Ulviprubart clinical trial information at ClinicalTrials.gov

Sirolimus

Sirolimus, also known as rapamycin, is an established, FDA-approved drug that has been used for many years to prevent kidney transplant rejection. A Phase IIb clinical trial of sirolimus in inclusion body myositis was completed in France, and results were reported in 2017. The results were promising enough to spur interest in further study. A Phase III trial is now underway in Australia and the United States.

Cure IBM Blog article on Rapamycin and Inclusion Body Myositis.

Sirolimus clinical trial information at ClinicalTrials.gov

Pioglitazone

A Phase I trial found that pioglitazone, a diabetes drug, improved some abnormal metabolic changes in IBM muscle. The study was small and ended early because of the COVID pandemic, and the results are preliminary.

More information about the pioglitazone trial for IBM

Arimoclomol

The clinical trial of Arimoclomol, a drug which helps with protein folding and clumping, did not demonstrate a benefit in inclusion body myositis.

Cure IBM blog article: Arimoclomol trial results for inclusion body myositis

Academic, medical journal article: A Randomized, Double-Blind, Placebo-Controlled Study of Arimoclomol in Patients with Inclusion Body Myositis

by Kevin Dooley, MD

Revised August 14, 2026