SFL-0821

SFL-0821 is an antibody-siRNA conjugate (ARC) being developed by Soufflé Therapeutics for the treatment of facioscapulohumeral muscular dystrophy (FSHD). It utilizes a proprietary discovery platform to enable myocyte-selective functional delivery of genetic therapeutics. The drug consists of a siRNA targeting the DUX4 transcript conjugated to a proprietary antibody that binds to a specific myocyte receptor, facilitating receptor-mediated uptake. By silencing the aberrant expression of DUX4 in skeletal muscle, SFL-0821 aims to prevent the cascade of transcriptional changes that lead to myocyte cell death. Non-clinical data in mouse models have demonstrated potent and persistent knockdown of DUX4 protein and regulated transcripts, which was associated with increased muscle mass and improved muscle function. Soufflé Therapeutics plans to initiate clinical trials for SFL-0821 in 2026.