Parsaclisib, a potent and highly selective phosphoinositide 3-kinase δ inhibitor, has shown clinical activity in relapsed/refractory (R/R) B-cell lymphoma. The phase 1 CITADEL-112 (NCT03424122) study assessed safety and efficacy of parsaclisib in combination with investigator choice standard of care (SOC; rituximab [Treatment A], rituximab plus bendamustine [Treatment B], or ibrutinib [Treatment C]) in 50 patients with R/R B-cell lymphoma. The most common treatment-emergent adverse events included neutropenia (62.5%, 50.0%, and 50.0% of patients in Treatments A, B, and C, respectively); diarrhea (37.5%) and anemia (31.3%) in Treatment A; abdominal pain, asthenia, diarrhea, and nausea (each 33.3%) in Treatment B; and increased alanine and aspartate aminotransferase (each 37.5%) in Treatment C. Objective responses were observed in 13 patients (81.3%) in Treatment A, 10 (55.6%) in Treatment B, and 8 (50.0%) in Treatment C. Parsaclisib combined with SOC therapies had an expected safety profile and promising efficacy in patients with R/R B-cell lymphomas.

Parsaclisib, a potent and selective phosphatidylinositol 3 kinase δ inhibitor, has been investigated for the treatment of B-cell malignancies and studied in patients with autoimmune diseases and myelofibrosis. The CITADEL-101 study (NCT02018861) assessed safety, tolerability, and preliminary efficacy of parsaclisib in patients with relapsed or refractory non-Hodgkin lymphoma. This study evaluated the cardiac safety of parsaclisib as monotherapy based on data from 72 patients enrolled in the CITADEL-101 study. Time-matched pharmacokinetic and ECG measurements were collected at specified times for 69 patients receiving monotherapy in doses of 5, 10, 15, 20, 30, and 45 mg once daily. Based on the categorical outlier analysis, no dose-dependent effect was observed on the incidence of outliers in QT interval corrected for heart rate (HR) by Fridericia\'s method (QTcF), HR, or cardiac conduction. Based on central tendency analysis, the least square means (LSMs) (90% confidence interval [CI]) of ΔQTcF from the central tendency analysis ranged from -6.83 (-18.8 to 5.19) to 4.75 ms (0.410-9.09) across dose groups (below 20 ms, the threshold of large QT effects) and was not considered dose dependent. Moreover, the LSMs of ΔHR, ΔPR interval, and ΔQRS interval were minor. From the concentration-ΔQTcF analyses, the predicted ΔQTcF (90% CI) for all dose levels was between 0.365 (-1.75 to 2.48) and 7.87 ms (0.921-14.8), with the highest upper limit of CIs well below 20 ms, and therefore, a large QT/QTc effect was ruled out up to the highest dose level (45 mg) investigated. Overall, parsaclisib at the dose ranges studied did not reveal concentration-dependent effects on change in QTcF and did not have a significant effect on HR or cardiac conduction.

UNASSIGNED: Phosphoinositide 3-kinase delta (PI3Kδ) inhibitors are a class of novel agents that are mainly used to treat B-cell malignancies. They function by inhibiting one or more enzymes which are part of the PI3K/AKT/mTOR pathway. Idelalisib is a first-in-class PI3Kδ inhibitor effective in patients with B-cell lymphoid malignancies.
UNASSIGNED: This article reviews the chemical structure, mechanism of action, and metabolic and toxicological properties of PI3Kδ inhibitors and discusses their clinical applications in monotherapy and in combination with other agents for the treatment of chronic lymphocytic leukemia (CLL). A search was conducted of PubMed, Web of Science, and Google Scholar for articles in English.
UNASSIGNED: PI3Kδ inhibitors hold potential for the treatment of B-cell malignancies, including CLL. However, their use is also associated with severe toxicities, including pneumonia, cytopenias, hepatitis, and rash. Newer drugs are in development to reduce toxicity with novel schedules and/or combinations.
UNASSIGNED: The development of novel PI3Kδ inhibitors might help to reduce toxicity and improve efficacy in patients with CLL and other B-cell lymphoid malignancies.

UNASSIGNED: Parsaclisib, a potent and highly selective PI3Kδ inhibitor, has shown clinical benefit in patients with relapsed or refractory (R/R) B-cell malignancies. This phase 2 study (CITADEL-203; NCT03126019, EudraCT 2017-001624-22) assessed efficacy and safety of parsaclisib monotherapy in patients with R/R follicular lymphoma (FL).
UNASSIGNED: Patients ≥18 years of age with histologically confirmed R/R FL (grade 1-3a) and prior treatment with ≥2 systemic therapies received parsaclisib 20 mg once daily (QD) for 8 weeks then parsaclisib 20 mg once weekly (weekly dosing group [WG]) or parsaclisib 20 mg QD for 8 weeks then parsaclisib 2.5 mg QD (daily dosing group [DG]); DG was selected for further assessment. Primary endpoint was objective response rate (ORR).
UNASSIGNED: At data cut-off (January 15, 2021), 126 patients had been treated (WG: n = 23; DG: n = 103). ORR (95% confidence interval [CI]) was 77.7% (68.4-85.3) with a complete response rate (95% CI) of 19.4% (12.3-28.4) in DG; median (95% CI) duration of response was 14.7 months (10.4-not estimable [NE]), median progression-free survival was 15.8 months (11.0-NE), and median overall survival was not reached. The most common any-grade treatment-emergent adverse events (TEAEs) among all treated patients included diarrhoea (n = 48, 38.1%), nausea (n = 31, 24.6%), and cough (n = 28, 22.2%); the most common grade ≥3 TEAEs were diarrhoea (n = 15, 11.9%), neutropenia (n = 13, 10.3%), and colitis (n = 7, 5.6%). Dose interruption, reduction, and discontinuation from TEAEs occurred in 46.8% (n = 59), 17.5% (n = 22), and 23.8% (n = 30) of patients, respectively.
UNASSIGNED: Treatment with parsaclisib demonstrated rapid and durable responses, and a manageable safety profile in patients with R/R FL.
UNASSIGNED: Incyte Corporation.

UNASSIGNED: Parsaclisib is a potent and highly selective PI3Kδ inhibitor that has shown clinical benefit in patients with relapsed/refractory (R/R) B-cell malignancies. In this phase 2 study (CITADEL-205; NCT03235544, EudraCT 2017-003148-19), the efficacy and safety of parsaclisib was evaluated in patients with R/R mantle cell lymphoma (MCL).
UNASSIGNED: Patients ≥18 years old with pathologically confirmed R/R MCL and prior treatment with 1-3 systemic therapies, with (cohort 1) or without (cohort 2) previous Bruton kinase inhibitor (BTKi) treatment, received oral parsaclisib 20 mg once-daily (QD) for 8 weeks, then either parsaclisib 20 mg once-weekly (weekly dosing group [WG]) or parsaclisib 2.5 mg QD (daily dosing group [DG]). The primary endpoint was objective response rate (ORR).
UNASSIGNED: At the primary analysis data cutoff on January 15, 2021, 53 patients in cohort 1 (BTKi-experienced) (WG, n = 12; DG: n = 41) and 108 patients in cohort 2 (BTKi-naive) (WG, n = 31; DG: n = 77) had received parsaclisib monotherapy. The BTKi-experienced cohort was closed after an interim analysis demonstrated limited clinical benefit. In the BTKi-naive cohort, the ORR (95% CI) for DG (dosing selected for further study) was 70.1% (58.6%-80.0%), with a complete response rate (95% CI) of 15.6% (8.3%-25.6%) and a median duration of response (95% CI) of 12.1 (9.0-not evaluable) months. Treatment-emergent adverse events (TEAEs) occurred among 90.7% (98/108) of all treated patients in the BTKi-naive cohort. Grade ≥3 TEAEs occurred among 62.0% (67/108) of patients, including diarrhoea (13.9%, 15/108) and neutropenia (8.3%, 9/108). Parsaclisib interruption, reduction, or discontinuation due to TEAEs occurred among 47.2% (51/108), 8.3% (9/108), and 25.0% (27/108) of patients, respectively. Fatal TEAEs were experienced by six patients and determined to be treatment-related in one patient.
UNASSIGNED: Parsaclisib, a potent, highly selective, PI3Kδ inhibitor demonstrated meaningful clinical benefits and a manageable safety profile (25.0% discontinuation rate, low incidences of individually reported grade ≥3 or serious adverse events) in R/R MCL patients with no prior BTKi therapy. Limited clinical benefit was observed with parsaclisib monotherapy in patients who had previously received BTKi treatment. Future development of PI3K inhibitors for NHL will require further investigation of dose optimisation to improve safety and long-term survival.
UNASSIGNED: Incyte Corporation.

Parsaclisib is a potent and highly selective PI3Kδ inhibitor that has shown clinical benefit with monotherapy in a phase 2 study in relapsed or refractory (R/R) follicular lymphoma (FL). CITADEL-102 (NCT03039114), a phase 1, multicenter study, assessed the efficacy of parsaclisib in combination with obinutuzumab and bendamustine in patients with R/R FL. Patients were ≥18 years of age with histologically confirmed and documented CD20-positive FL, and R/R to previous rituximab-containing treatment regimens. Part one (safety run-in) determined the maximum tolerated dose of parsaclisib in combination with standard dosage regimens of obinutuzumab and bendamustine. Part two (dose expansion) was an open-label, single-group design evaluating safety, tolerability (primary endpoint), and efficacy (secondary endpoint) of parsaclisib combination therapy. Twenty-six patients were enrolled in CITADEL-102 and all patients received parsaclisib 20 mg once daily for 8 weeks, followed by 20 mg once weekly thereafter, in combination with obinutuzumab and bendamustine. One patient in safety run-in experienced a dose-limiting toxicity of grade 4 QT interval prolongation that was considered related to parsaclisib. Eight patients (30.8%) discontinued treatment due to treatment-emergent adverse events (TEAEs) of colitis (2 [7.7%]), alanine aminotransferase and aspartate aminotransferase increase (both in one patient [3.8%]), neutropenia, thrombocytopenia, QT prolongation, tonsil cancer, and maculopapular rash (each 1 [3.8%]). The most common reported TEAEs were pyrexia (53.8%), neutropenia (50.0%), and diarrhea (46.2%). Twenty-three patients (88.5%) experienced grade 3 or 4 TEAEs; the most common were neutropenia (34.6%), febrile neutropenia (23.1%), and thrombocytopenia (19.2%). Seventeen patients (65.4%) had a complete response and 3 patients (11.5%) had a partial response, for an objective response rate of 76.9%. Overall, results from CITADEL-102 suggest that the combination of parsaclisib with obinutuzumab and bendamustine did not result in unexpected safety events, with little evidence of synergistic toxicity, and demonstrated preliminary efficacy in patients with R/R FL who progressed following prior rituximab-containing regimens.

In this review article we provide a critical insight into recent reports evaluating innovative therapies for warm type autoimmune hemolytic anemia (wAIHA). Among published articles, we selected two reports on the use of the proteasome inhibitor bortezomib in association with dexamethasone or rituximab, one study on the spleen tyrosine kinase inhibitor fostamatinib, and a retrospective study on recombinant erythropoietin (rEPO). Among recent scientific communications, we discussed a report on the phosphoinositide 3-kinase delta inhibitor (PI3Kδi) parsaclisib. All studies highlighted a good efficacy although to be confirmed in larger trials and with limitations due to the heterogeneity of wAIHA patients enrolled, the small number of subjects, the concomitant medications allowed, and the short follow-up. Ongoing trials include new B-cell/plasma-cell targeting agents such as the Bruton tyrosine kinase inhibitors ibrutinib and rilzabrutinib, and the anti-CD38 MoAbs daratumumab and its analogue isatuximab. Further drugs in clinical trials target the complement cascade in wAIHA with complement activation, such as the C3 inhibitor pegcetacoplan and the C1q inhibitor ANX005. Finally, an interesting and non-immuno-toxic strategy is to remove the pathogenic autoantibodies via blocking the neonatal Fc receptor, by intravenous nipocalimab and subcutaneous RVT-1401. Such novel agents targeting the several immunopathological mechanisms acting in wAIHA and their possible combination, will increase the therapeutic armamentarium and possibly fill the gap of wAIHA relapsed after/refractory to rituximab. Moreover, these new target therapies may represent a tool for the unmet need of very acute cases.

Decreasing efficacy over time and initial suboptimal response to Janus kinase (JAK) inhibitors such as ruxolitinib in a subset of patients are critical clinical challenges associated with myeloproliferative neoplasms (MPNs), primarily myelofibrosis.
The role of phosphatidylinositol-3 kinase (PI3K) in MPN disease progression and treatment resistance and as a potential therapeutic target in patients who experience loss of response to JAK inhibition is discussed. Understanding the complex signaling networks involved in the pathogenesis of MPNs has identified potentially novel therapeutic targets and treatment strategies, such as inhibiting other signaling pathways in addition to the JAK/signal transducer and activator of transcription (STAT) pathway. PI3K plays a crucial role downstream of JAK signaling in rescuing tumor cell proliferation, with PI3Kδ being particularly important in hematologic malignancies. Concurrent targeting of both PI3K and JAK/STAT pathways may offer an innovative therapeutic strategy to maximize efficacy.
Based on our understanding of the underlying mechanisms and the role of PI3K pathway signaling in the loss of response or resistance to JAK inhibitor treatment and initial results from clinical studies, the combination of parsaclisib (PI3Kδ inhibitor) and ruxolitinib holds great clinical potential. If confirmed in larger clinical trials, parsaclisib may provide more treatment options and improve clinical outcomes for patients with MPNs.

Phosphoinositide 3-kinases (PI3Ks) signaling regulates key cellular processes, such as growth, survival and apoptosis. Among the three classes of PI3K, class I is the most important for the development, differentiation and activation of B and T cells. Four isoforms are distinguished within class I (PI3Kα, PI3Kβ, PI3Kδ and PI3Kγ). PI3Kδ expression is limited mainly to the B cells and their precursors, and blocking PI3K has been found to promote apoptosis of chronic lymphocytic leukemia (CLL) cells. Idelalisib, a selective PI3Kδ inhibitor, was the first-in-class PI3Ki introduced into CLL treatment. It showed efficacy in patients with del(17p)/TP53 mutation, unmutated IGHV status and refractory/relapsed disease. However, its side effects, such as autoimmune-mediated pneumonitis and colitis, infections and skin changes, limited its widespread use. The dual PI3Kδ/γ inhibitor duvelisib is approved for use in CLL patients but with similar toxicities to idelalisib. Umbralisib, a highly selective inhibitor of PI3Kδ and casein kinase-1ε (CK1ε), was found to be efficient and safe in monotherapy and in combination regimens in phase 3 trials in patients with CLL. Novel PI3Kis are under evaluation in early phase clinical trials. In this paper we present the mechanism of action, efficacy and toxicities of PI3Ki approved in the treatment of CLL and developed in clinical trials.

Parsaclisib, a potent, selective, next-generation PI3Kδ inhibitor, has shown clinical benefit in patients with relapsed or refractory B-cell lymphoma. We undertook a phase Ib study (CITADEL-111) evaluating safety, pharmacokinetics, and efficacy of parsaclisib in Japanese patients with relapsed or refractory B-cell malignancies. Patients received oral parsaclisib daily for 8 weeks then once weekly (10-mg dose, n = 3; 20-mg dose, n = 14). Pharmacokinetic samples were collected on days 1, 8, and 15, and efficacy was monitored according to Lugano criteria. At data cut-off (August 14, 2020), 6 patients (35.3%) remained on study treatment and 11 (64.7%) discontinued due to progressive disease (9 [52.9%]) or adverse events (2 [11.8%]). Median duration of treatment was 8.3 (range, 0.3-24.4) months. The most commonly reported nonhematologic adverse events were constipation (6 [35.3%]), nausea, and pyrexia (each 4 [23.5%]). Five patients (29.4%) experienced treatment-emergent new or worsening decreased neutrophils to grade 3 or 4. No treatment-emergent worsening in aminotransferase elevations to grade 3 or 4 were observed. Ten patients (58.8%) required dose interruption and 5 (29.4%) dose reduction. Body weight-normalized parsaclisib exposure was comparable between Japanese and Western patients. Objective response rate was 100% in follicular lymphoma (9 of 9 patients, including complete response in 2 patients [22.2%]) and marginal zone lymphoma (2 of 2 patients), and 16.7% in diffuse large B-cell lymphoma (1 of 6 patients). Results observed in Japanese patients with relapsed or refractory follicular or marginal zone lymphoma support further clinical development of parsaclisib in these patient populations.