The Efficacy of Duvelisib Monotherapy Following Disease Progression on Ofatumumab Monotherapy in Patients with Relapsed/Refractory CLL or SLL in the DUO™ Crossover Extension Study

Background: Duvelisib, an oral dual inhibitor of PI3K-δ,γ, is being developed for the treatment of hematologic malignancies, including relapsed/refractory (RR) CLL/SLL. In the Phase 3 DUO study (NCT02004522) duvelisib monotherapy demonstrated significant improvement compared to ofatumumab monotherapy (PFS 13.3 vs 9.9 mo. p < 0.0001; ORR 74% vs 45% p < 0.0001) with a manageable safety profile (Flinn, ASH 2017). Study IPI-145-12 (NCT02049515) is an open-label, optional, crossover extension study where pts with confirmed progressive disease (PD) on DUO were given the option to receive the opposite treatment. Herein we present data for the 89 pts who voluntarily rolled over following PD on ofatumumab on DUO and received duvelisib on Study IPI-145-12.