This study is a randomized, parallel, double-blind, placebo-controlled, subcutaneous administration Phase II dose-exploration clinical trial aimed at evaluating the efficacy, safety, PK, PD, and immunogenicity characteristics of SLN12140 at different doses in IgA nephropathy subjects who have previously received standard treatment (the standard treatment drugs allowed in this study include: angiotensin-converting enzyme inhibitors \[ACEi\], angiotensin II receptor blockers \[ARB\], and sodium-glucose co-transporter 2 inhibitors \[SGLT2i\]) but have poor control.
The study is divided into four stages, including a screening period of up to 8 weeks, an introduction period of up to 12 weeks, a 40-week double-blind period (including a 36-week treatment period and a 4-week safety follow-up period; all subjects in the three dose groups who are willing to continue treatment and are judged by the investigator to potentially benefit from subsequent treatment will enter the open-label extension period for continued treatment after completing the double-blind period), and a 56-week open-label extension period (all subjects in the three dose groups who are willing to continue treatment and are judged by the investigator to potentially benefit from subsequent treatment will continue SLN12140 at the same dose group \[the optimal dose\], including a 52-week open treatment period and a 4-week safety follow-up period).