Patients aged ≥18 years with relapsed CD20-positive indolent B-cell lymphoma received copanlisib (45 mg, increasing to 60 mg if no dose-limiting toxicities) weekly on an intermittent schedule with R-B or R-CHOP...Among evaluable patients, objective response rates were 90% (5 complete, 4 partial) and 100% (3 complete, 7 partial) with copanlisib plus R-B and R-CHOP, respectively....Copanlisib is the first PI3K inhibitor to demonstrate safe, tolerable, and effective combinability with immunochemotherapy in patients with relapsed indolent B-cell lymphoma...