CAMBRIDGE, Mass. — September 17, 2026

Biogen announced publication of prespecified adolescent subgroup results from the Phase 3 VALIANT study of EMPAVELI® (pegcetacoplan) in the Clinical Journal of the American Society of Nephrology. The analysis evaluated adolescents aged 12 to 17 years with C3 glomerulopathy (C3G) or primary immune complex membranoproliferative glomerulonephritis (IC-MPGN). At Week 26, EMPAVELI-treated adolescents achieved a 75% relative reduction in proteinuria versus placebo, while kidney function remained stable. The findings add to the evidence supporting EMPAVELI as a treatment option for younger patients with these rare complement-mediated kidney diseases.

VALIANT Shows Significant Proteinuria Reduction in Adolescents

The adolescent cohort included 55 patients, representing nearly half of the overall VALIANT study population and one of the larger randomized datasets available for this patient population. At Week 26, 71% of adolescents treated with EMPAVELI achieved at least a 50% reduction in proteinuria, compared with 4% receiving placebo. The relative reduction in proteinuria versus placebo was 75% (95% CI: 59%-84%; nominal p<0.001), with improvements observed as early as Week 4 and continuing through Week 26. In addition, 57% of EMPAVELI-treated adolescents achieved both stable kidney function and at least a 50% reduction in proteinuria, compared with 4% of placebo-treated patients. The adolescent findings were consistent with outcomes observed in the broader VALIANT population.

EMPAVELI Expands Pediatric Kidney Disease Treatment

EMPAVELI is designed to target excessive activation of the complement cascade through inhibition of complement component C3, a pathway implicated in the progression of C3G and primary IC-MPGN. The diseases can begin early in life and may lead to progressive kidney damage and kidney failure. The recent U.S. FDA label expansion allows EMPAVELI to be used in adult and pediatric patients aged 12 years and older with C3G or primary IC-MPGN to reduce proteinuria and the loss of kidney function. The update was supported by 52-week VALIANT efficacy and safety data showing sustained effects on proteinuria and preservation of estimated glomerular filtration rate. Biogen reported that EMPAVELI was well tolerated in adolescents, with a safety profile consistent with the overall VALIANT population..

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Biogen Advances EMPAVELI in Rare Renal Diseases

The VALIANT results strengthen the clinical evidence base for EMPAVELI in adolescents with complement-mediated kidney diseases, while extending the product’s development and regulatory progress following the recent U.S. label expansion. VALIANT was a randomized, placebo-controlled, double-blind Phase 3 study involving 124 patients aged 12 years and older with C3G or primary IC-MPGN, including patients with native kidney disease and post-transplant recurrence. Participants received EMPAVELI or placebo twice weekly for 26 weeks, followed by a 26-week open-label period. EMPAVELI carries important safety considerations because complement inhibition can increase the risk of serious infections caused by encapsulated bacteria, and treatment is subject to a REMS program in the United States. The new adolescent data provide additional clinical evidence for Biogen’s strategy to address progressive complement-mediated renal diseases across younger and adult patient populations.

Source: Biogen, press release