The following article features coverage from the 2021 American Society of Hematology Annual Meeting. Click here to read more of Cancer Therapy Advisor’s conference coverage.

The PI3K-delta inhibitor parsaclisib demonstrated “rapid and durable responses” in patients with relapsed/refractory follicular lymphoma (FL), according to a presentation at the 2021 American Society of Hematology (ASH) Annual Meeting.

The results come from the phase 2 CITADEL-203 trial ( Identifier: NCT03126019). The trial included 126 patients with grade 1-3a, relapsed/refractory FL who were eligible for transplant. 

The patients’ median age was 67.5 years (range, 40-88 years), and 56% were men. Patients had received a median of 2 prior systemic therapies (range, 1-8). 

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Initially, patients received parsaclisib at 2 different dosing schedules. In the weekly dosing group, patients received 20 mg once daily for 8 weeks, followed by 20 mg once weekly continuously (n=23). 

In the daily dosing group, patients received 20 mg once daily for 8 weeks, followed by 2.5 mg daily continuously (n=103). After an interim analysis, enrollment continued in the daily dosing group and was closed in the weekly dosing group. 

The primary endpoint was objective response rate (ORR) by an independent review committee. The median follow-up was 20.6 months overall and 17.6 months for patients in the daily dosing group.

In all 126 treated patients, the ORR was 75.4%, with 18% of patients achieving a complete response (CR) and 57% having a partial response (PR). An additional 15% of patients had stable disease (SD). 

Among the 103 patients in the daily dosing group, the ORR was 77.7%, the CR rate was 19%, the PR rate was 58%, and 13% of patients had SD.

The median duration of response was 14.7 months for all patients and 14.7 months for the daily dosing group. The median progression-free survival was 14.0 months and 15.8 months, respectively.

A total of 87 patients (69.0%) discontinued treatment, mostly due to progressive disease (36.5%) or adverse events (21%).

The rate of grade 3 or higher treatment-emergent adverse events (TEAEs) was 59% for the entire cohort. The most common grade 3 or higher TEAEs were diarrhea (12%) and neutropenia (10%). 

Serious TEAEs occurred in 45% of patients. The most common were diarrhea (7%) and colitis (6%). There were 2 fatal events attributable to parsaclisib — Stevens-Johnson syndrome and pneumonia.

Disclosures: This research was supported by Incyte Corporation. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of the ASH 2021 meeting by visiting the conference page.


Lynch RC, Avigdor A, McKinney M, et al. Efficacy and safety of parsaclisib in patients with relapsed or refractory follicular lymphoma: Primary analysis from a phase 2 study. Presented at ASH 2021; December 11-14, 2021. Abstract 813.