FDA delays Sobi gout therapy, citing manufacturing issues

The U.S. Food and Drug Administration declined to approve Sobi’s gout therapy after flagging manufacturing and contract-facility issues, not questions about whether the drug worked or was safe. The complete response letter arrived on June 26, 2026, one day before the agency’s June 27 decision deadline for the biologics license application it had accepted on September 10, 2025.

The treatment, NASP, short for nanoencapsulated sirolimus plus pegadricase, was built as a four-week infusion for adults with uncontrolled gout. Sobi puts the U.S. market opportunity at roughly 200,000 people whose serum uric acid remains above 6 mg/dL despite oral urate-lowering therapy and who continue to suffer debilitating flares and, in many cases, tophi. The disease is the most common form of inflammatory arthritis, and persistent high uric acid can drive recurrent swelling, pain and long-term joint damage.

Sobi’s filing rested on the Phase 3 DISSOLVE I and II studies, which supported the application through the primary endpoint of sustained serum uric acid control for at least 80% of the treatment period over six months. At the 2025 American College of Rheumatology meeting, company presentations showed fewer gout flares, fewer tender and swollen joints, lower serum uric acid and better quality of life. A later presentation put pooled response rates at 51% for the higher dose and 43% for the lower dose.

The FDA identified deficiencies tied to chemistry, manufacturing and controls and to contract manufacturing facilities, while not raising safety or efficacy concerns. Sobi will seek a meeting with the FDA, work with contract manufacturers to address the problems and then decide when to resubmit. In May 2026, the company announced its acquisition of Arthrosi Therapeutics.