This is a single-arm extension study to investigate the long-term safety, tolerability, and efficacy of lunsekimig in adult participants with inadequately controlled CRSwNP who have completed a previous lunsekimig CRSwNP clinical study (also referred to as the parent study ACT18207). The study duration will be up to approximately 56 weeks per participant, 52 weeks of treatment period, and 4 weeks of follow-up.