CITADEL-204 was a Phase II study evaluating the PI3 kinase δ inhibitor parsaclisib in patients with relapsed/refractory marginal zone lymphoma. The study was originally designed to evaluate two cohorts, BTK inhibitor-experienced and the BTK inhibitor-naive patients with marginal zone lymphoma. Due to enrollment feasibility issues, we did close the BTK inhibitor-experienced cohort and focused on those who were BTK inhibitor-naive...
CITADEL-204 was a Phase II study evaluating the PI3 kinase δ inhibitor parsaclisib in patients with relapsed/refractory marginal zone lymphoma. The study was originally designed to evaluate two cohorts, BTK inhibitor-experienced and the BTK inhibitor-naive patients with marginal zone lymphoma. Due to enrollment feasibility issues, we did close the BTK inhibitor-experienced cohort and focused on those who were BTK inhibitor-naive. In total, we enrolled 100 patients. They were started with parsaclisib, 20 milligrams once daily. Then patients were then allocated one-to-one into a 2.5 milligrams daily dosing or 20 milligrams once-weekly dosing. The vast majority, 72 of the 100, were eventually treated at the 2.5 milligrams once-daily dosing for maintenance and that was the dose put forth to move forward in Phase 2 dosing.
From this study, what we demonstrated is that parsaclisib was effective in multiple different subtypes of marginal zone lymphoma: nodal, splenic marginal zone lymphoma, and extranodal. We didn’t notice any specific efficacy differences between the three different arms. Toxicity, which has been a concern obviously with PI3 kinase δ inhibitors, and that’s part of the reason why we explored the maintenance dosing. We did see continued reports of diarrhea, colitis, and infection. But compared to what we see with daily dosing, frequencies are much reduced with the use of the maintenance dosing.
Moving forward, obviously, with marginal zone lymphoma, there are a few approved agents: BTK inhibitors, R². But parsaclisib does fit in quite appropriately with the available PI3 kinase δ inhibitors that are currently available. That gives another oral option for these patients pending further maturation of the data and how the company puts forth the medication.