#277 Update to the long-term safety and efficacy of iptacopan in C3G: 33-month extension study data from patients enrolled in a phase 2 study
Authors: Nester Carla M , Eisenberger Ute , Karras Alexandre , Quintrec Moglie Le , Lightstone Liz , Praga Manuel , Remuzzi Giuseppe , Romeo Maria José Soler , Liu Junhao , Meier Matthias , Webb Nicholas , Wong Edwin 
Published: May 2024

Background and Aims

Complement 3 glomerulopathy (C3G), due to dysregulation of the alternative complement pathway (AP), is an ultra-rare primary glomerulonephritis. Iptacopan (LNP023) is an oral, proximal complement inhibitor that specifically binds factor B and inhibits the AP. We previously reported the primary endpoint data from the Phase (Ph) 2 extension study (NCT03955445), showing proteinuria reduction (57% [p &lt; 0.0001]) and estimated glomerular filtration rate (eGFR) improvement (by +6.83 mL/min/1.73 m2 [p = 0.0174]) from baseline, following 12 months (M) of treatment with iptacopan in patients with C3G. Here we present further long-term efficacy and safety data from patients with C3G and recurrent C3G (post-kidney transplantation), who completed 33M of treatment with iptacopan (NCT03955445).

Method

Adults with C3G disease (Cohort A) or C3G recurrence post-transplantation (Cohort B) received iptacopan 200 mg twice-daily (bid) for at least 12 weeks in the Ph2 study (NCT03832114) before entering the open label extension study (NCT03955445). Long-term efficacy was assessed by a number of renal endpoints, including a 2-component composite renal endpoint (eGFR stability [≤10% reduction] and ≥50% proteinuria reduction). Long-term safety and tolerability of iptacopan was continually monitored.

Results

Of 27 patients completing the Ph2 study (NCT03832114), 26 (16 Cohort A, 10 Cohort B) entered the extension study treatment with iptacopan 200 mg bid; 22 patients (14 Cohort A, 8 Cohort B) completed the 33M visit (i.e., 3M in the Ph2 study and 30M in the extension study). In Cohort A, 42.9% of patients met the 2-component composite renal endpoint criteria at 33M. Proteinuria (first morning void [FMV] urine protein–creatinine ratio [UPCR]) was reduced by 41% (p = 0.0097) compared to baseline. eGFR stabilized or improved in most patients (13/16) over time and change from baseline at the 33M time-point was −3.18 mL/min/1.73 m2 (p = 0.3512). C3 levels increased by 275% (p &lt; 0.0001) from baseline. In Cohort B, eGFR change from baseline at the 33M time-point was −6.34 mL/min/1.73 m2 (p = 0.0571), and C3 levels increased by 102%. Baseline proteinuria values (FMV UPCR) were within the normal range for most participants in Cohort B and remained so during iptacopan treatment. Iptacopan was generally well-tolerated, and most adverse events were of mild severity in both cohorts. Biomarkers demonstrated substantial AP inhibition.

Conclusion

Long-term treatment with iptacopan was associated with sustained reduction in proteinuria in patients with C3G (Cohort A), and preservation of eGFR. These improvements in kidney function were associated with substantial inhibition of the AP leading to normalization of serum C3. Iptacopan was well-tolerated with no new safety findings in the long term, in patients with C3G, including those with recurrence post-transplantation on top of broad triple immunosuppression. The ongoing Ph3 APPEAR-C3G study (NCT04817618) is evaluating the efficacy and safety of iptacopan in patients with C3G.