This study randomly assigned participants in a 2:1 ratio to receive either zanubrutinib plus obinutuzumab or obinutuzumab alone. The assignment considered how many prior treatments participants had received, whether their cancer had stopped responding to rituximab, and whether they were enrolled in Mainland China or other regions. Each treatment cycle lasted 28 days, with zanubrutinib taken by mouth twice daily and obinutuzumab given intravenously on a set schedule, followed by optional maintenance for up to 24 months. Participants who had obinutuzumab alone could have switched to the combination treatment if their disease worsened or did not respond after 12 months, if confirmed by an independent review.