The PRESERVE study is a Phase 3b, multicenter, single-arm, open-label clinical trial designed to explore the efficacy and safety of pegcetacoplan in preventing or delaying the recurrence of C3 glomerulopathy (C3G) or primary immune-complex membranoproliferative glomerulonephritis (IC-MPGN) following kidney transplantation. Recurrence of these diseases after transplantation is common and can lead to graft dysfunction and loss. Pegcetacoplan is a complement C3/C3b inhibitor that has demonstrated activity in patients with native kidney undermine disease and recurrent disease after transplantation. The study aims to assess whether initiating pegcetacoplan at the time of kidney transplantation, before recurrence occurs, may delay the recurrence and support long-term graft outcomes. Participants will receive pegcetacoplan in addition to standard post-transplant care and will be followed to evaluate disease recurrence, kidney function, graft outcomes, safety, and tolerability.