The autoimmune disease lupus has no cure, and current treatment is limited in its effectiveness in reducing symptoms and controlling damage to the body. Now, scientists report they have begun phase 2 clinical trials with a compound that, in mice, not only prevents lupus-like symptoms, but also reverses signs of organ damage caused by the disease and prevents death.
“Few new therapies have succeeded, but we believe our compound could be an effective treatment for lupus,” says Alaric Dyckman, PhD. The disease affects 5 million people worldwide, according to the Lupus Foundation of America. Symptoms include rashes, extreme fatigue, pain, inflammation and deterioration of organs, such as the kidneys and heart, which can lead to death.
The researchers will present their results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2022 is a hybrid meeting being held virtually and in-person Aug. 21–25, with on-demand access available Aug. 26–Sept. 9.
Lupus develops when the immune system attacks the body’s tissues. Years ago, researchers began suspecting that this process involved toll-like receptors (TLRs) 7 and 8, which are cellular proteins that activate the immune system when they detect viral RNA or mistakenly identify a person’s own RNA as a threat.
“Genetic data and evaluations of injectable treatments suggested TLR7 and 8 could be drug targets for lupus. What was missing was an ability to directly block these receptors with small molecules that could be taken orally,” explained Dr Dyckman. So in 2010, he and other scientists at Bristol Myers Squibb (BMS) set out to develop such compounds.
New options would be welcome, since many patients don’t respond fully to current medications. The two approved therapies that were specifically developed for lupus reduce activity of specific immune system components: AstraZeneca’s anifrolumab blocks an interferon receptor, while GlaxoSmithKline’s belimumab reduces the survival of B cells. Other treatments include steroids and other general immune suppressants, anti-malarials, anti-inflammatories and anticoagulants. However, anifrolumab and belimumab must be given by injection or infusion, Dr Dyckman noted, while steroids and general immune suppressants are associated with safety concerns and were not originally designed to treat lupus.
The BMS researchers started by screening the company’s compound collection for molecules that could block TLR7/8 signalling. The team refined the search further to improve interaction with other receptors, and potency, and enablee oral dosing. The resulting compound, afimetoran, binds to the target TLRs, inhibiting their operation to achieve beneficial activity. Like anifrolumab, it interferes with interferon, and like belimumab, it controls damage from overactive B cells. It also inhibits the production of multiple proinflammatory cytokines that cause a lot of tissue damage in lupus.
“With afimetoran, not only could we prevent the development of lupus-like symptoms in mice before their disease onset, but we could actually reverse the symptoms and prevent death in animals that were days or weeks away from succumbing to the disease,” Dr Dyckman said. “We hadn’t seen that reversal with other mechanisms we had evaluated, so we were particularly excited about that finding.” Dr Dyckman said that he believes afimetoran effects together may let it control lupus as well as or better than existing treatments, doing it through an oral route.
Afimetoran also combined well with corticosteroid treatments in mice, so patients might be able to use lower doses of steroids and reducing associated side effects.
Phase 1 clinical trials of afimetoran have been completed. The trials showed that a low, once-daily oral dose was safe in healthy patients and could almost completely block signalling through TLR7/8. And now, a phase 2 trial to test its effectiveness in lupus patients is underway. Because of its mode of action, Dr Dyckman said, it may also work in other autoimmune disorders, such as psoriasis or arthritis.
BMS is testing other compounds against lupus, such as deucravacitinib, an oral, selective tyrosine kinase 2 (TYK2) inhibitor that is moving into phase 3 studies. Other companies are also making progress. Merck, for instance, is evaluating its own oral TLR7/8 blocker, enpatoran, in phase 2 trials.
Despite intensive efforts to develop new therapies over the past several decades, few have succeeded. “So getting a lot of shots on goal is important,” Dr Dyckman said. “Also, lupus is such a heterogeneous disease that it’s unlikely that any single approach will provide relief for all of the patients out there.”
Source: EurekAlert!
