Treatment and sampling schedule. Every “X” on the sampling schedule represents an FCM and ctDNA sample. Benda, bendamustine; C1, cycle 1; C2, cycle 2; C3, cycle 3; C4, cycle 4; C5, cycle 5; C6, cycle 6; DB1, debulking cycle 1; DB2, debulking cycle 2; FCM, flow cytometry; IR, initial response assessment; M1, maintenance staging 1; M2, maintenance staging 2; Mx, maintenance stagings 3 to 8; obi, obinutuzumab; RE, final restaging.