Copanlisib Has Activity As a Single Agent and in Combination with Carfilzomib and Response Correlates with Phospho-S6 Level

The reversible, pan-class I PI3K inhibitor copanlisib (BAY 80-6946) has potent activity against the alpha and delta isoforms. Using a panel of 20 multiple myeloma cell lines, we show the in vitro activity of copanlisib as a single agent and in combination with carfilzomib. Sensitive cell lines had lower baseline and post-treatment levels of phospho-S6 (p-S6) resulting in a potential biomarker of response and a potential pharmacodynamic biomarker.