Terminal Complement Inhibition: Promising Results in IgAN from the I CAN Trial

Terminal complement inhibition with Ultomiris (ravulizumab) delivered a statistically significant and clinically meaningful reduction in proteinuria at week 34 in adults with immunoglobulin A nephropathy (IgAN) at high risk of progression. According to the prespecified interim analysis of the Phase III I CAN trial, this effect emerged as early as week 10. These results position terminal complement inhibition as a promising disease-modifying approach in IgAN, a condition that still carries substantial unmet need despite currently available therapies.

Proteinuria Drop Signals Long-Term Kidney Protection

The most striking outcome is the rapid and sustained lowering of 24-hour urine protein creatinine ratio (UPCR) at week 34, with reductions already visible by week 10. In IgAN, proteinuria is a validated surrogate for kidney disease progression; reductions of this magnitude are strongly linked to slower decline toward end-stage kidney disease. Patients in the trial were already receiving stable standard-of-care therapy for at least three months, confirming that ravulizumab provides meaningful incremental benefit. By blocking C5, terminal complement inhibition directly interrupts the uncontrolled complement activation triggered by IgA immune complex deposition, addressing a core driver of glomerular damage rather than simply treating symptoms. The safety profile remained consistent with previous experience across multiple indications.

Unravelling Complement-Driven Kidney Damage

Immunoglobulin A nephropathy develops when abnormal IgA proteins form immune complexes that deposit in the kidneys, activating the complement cascade and causing terminal complement-mediated inflammation. This leads to progressive glomerular injury, chronic kidney disease, and, in many cases, kidney failure. More than 560,000 people are diagnosed with IgAN across the United States, EU5 and Japan, with over half of those showing high proteinuria or reduced kidney function at risk of reaching kidney failure within ten years.

Adaptive Phase III Design Links Early Surrogate to Clinical Outcomes

The I CAN trial (ALXN1210-IgAN-320) is a global, randomised, double-blind, placebo-controlled Phase III study that enrolled approximately 510 adults at risk of progression in 28 countries. Participants received weight-based loading and maintenance dosing of Ultomiris every eight weeks or matching placebo for 106 weeks, on top of stable background therapy. The interim analysis met the first primary endpoint—change from baseline in 24-hour UPCR at week 34—while the second primary endpoint of eGFR change at week 106 continues to be evaluated. Key secondary endpoints include the proportion of patients achieving at least 50 percent UPCR reduction, time to sustained eGFR decline, and time to composite kidney events. This adaptive dual-primary-endpoint design efficiently connects an early surrogate marker with a later clinical outcome, an approach particularly valuable for regulatory and reimbursement decisions in rare kidney diseases.

HEOR and Market Access Implications of Early Disease Modification

These interim findings have clear implications for health economics, outcomes research, market access and reimbursement. Rapid, statistically significant proteinuria reduction at week 34, with effects seen by week 10, strengthens the case for accelerated approval pathways and conditional reimbursement based on validated surrogates. From a health economic perspective, delaying progression to dialysis or transplantation could deliver substantial cost savings and reduce associated cardiovascular burden. The consistent safety profile, already well-established in paroxysmal nocturnal haemoglobinuria, atypical haemolytic uraemic syndrome, generalised myasthenia gravis and neuromyelitis optica spectrum disorder, may further support favourable payer assessment. As the trial advances toward the week-106 eGFR readout, robust modelling of the relationship between early UPCR response and long-term kidney preservation will be essential to build comprehensive value dossiers.