In post-hoc analyses of the Phase 3 DISSOLVE trials in uncontrolled gout, nanoencapsulated sirolimus plus pegadricase (NASP) drove rapid and durable biochemical and clinical effects: median serum uric acid fell by 97–98% through Week 24 versus a 1.5% increase on placebo, mean serum uric acid generally remained at or below 2.0 mg/dL while placebo remained above 6 mg/dL, tender and swollen joint counts were roughly halved versus placebo, gout flares in Weeks 13–24 were 2.3- to 5.7-fold fewer than placebo, and complete tophus resolution at Week 24 reached 31–48% versus 5% on placebo. NASP was generally well tolerated in the blinded extension of DISSOLVE I, with low discontinuation and no new safety signals reported.
The data were part of 15 Sobi abstracts at ACR Convergence 2025, spanning three programs. For NASP (formerly SEL-212), the company is leaning on DISSOLVE outcomes ahead of a June 27, 2026, PDUFA date following BLA acceptance in September. For Gamifant (emapalumab), now approved in the U.S. for MAS in Still’s disease, pooled analyses across two prospective trials indicated responses across MAS subtypes and showed marked reductions in PD markers of IFNγ activity among responders, including CXCL9 and ferritin. And for Vonjo (pacritinib), Sobi highlighted the first international randomized, double-blind, placebo-controlled Phase 2 dose-finding study in VEXAS syndrome and advanced field infrastructure with consensus definitions for VEXAS flare and a new disease activity index.
Strategically, Sobi is tightening its positioning in rare inflammatory conditions by combining registrational momentum with field shaping. In gout, the company is directly challenging the entrenched uricase paradigm by pairing a uricase with tolerogenic sirolimus to blunt anti-drug antibodies, aiming to deliver sustained urate control without co-therapy complexity. The emphasis at ACR on flares, tophus resolution, and HRQOL moves beyond biochemical surrogacy toward functionally meaningful outcomes likely to feature in FDA deliberations. In MAS, the company is broadening the clinical utility of Gamifant with evidence that aligns with regulators’ preference for mechanism-linked PD readouts, potentially informing dose optimization and earlier intervention strategies. In VEXAS, a heterogeneous, newly defined syndrome, the decision to run a robust randomized trial while underwriting common language on flares and disease activity is a classic category-building move that can lower future development friction.
For sites and CROs, NASP’s sequential infusion model and monthly cadence will demand infusion chair planning, flare adjudication workflows, and consistent capture of PROs and joint assessments; tophus evaluation methods may need standardization across networks. The MAS program’s biomarker signal supports tighter lab logistics and could seed stratified protocols that taper steroids more consistently across centers. VEXAS will test cross-specialty coordination between hematology and rheumatology sites, while the new flare and activity instruments, if adopted widely, could reduce endpoint variability and streamline monitoring plans. Vendors with digital flare diaries, image capture for tophi, and centralized biomarker capabilities may find near-term demand.
Key watch items are whether FDA prioritizes NASP’s clinical outcome signals alongside urate-lowering, the need for an advisory committee, and any postmarketing requirements to confirm flare and tophus benefits in broader practice. In MAS, uptake will hinge on operationalizing rapid diagnosis and infection surveillance while exploring biomarker-guided dosing. For VEXAS, recruitment pace, dose selection from Part 1 of PAXIS, and real-world validation of the VEXAS-DAI and flare criteria will determine how quickly the space moves toward registrational endpoints. The through line is Sobi’s bet that operational simplicity, standardized endpoints, and mechanism-tied biomarkers can convert small-population inflammation programs into durable franchises.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
