Adding Umbralisib and Ublituximab (U2) to Ibrutinib in Patients with CLL: A Phase II Study of an MRD-Driven Approach.

PURPOSE: Ibrutinib has transformed the management of chronic lymphocytic leukemia (CLL), though its use is limited by toxicity and resistance. In this study, we utilized an "add on" approach for patients who had been treated with ibrutinib in the front-line or relapsed/refractory settings with detectable MRD. Umbralisib and ublituximab (U2) were added on to ibrutinib, patients were treated until achieving undetectable-MRD (U-MRD), and then they entered a period of treatment-free observation (TFO). PATIENTS AND METHODS: Patients were eligible if they received ibrutinib in any line of therapy for at least 6 months and had detectable MRD (flow cytometry, <1 cell in 10-4 cutoff for U-MRD). U2 was added to ibrutinib, and patients were monitored serially for MRD. Once U-MRD was achieved or a total of 24 cycles were administered, patients entered a period of TFO. The primary study objective was rate of U-MRD. Secondary endpoints included safety and durability of clinical benefit after treatment discontinuation. RESULTS: Twenty-eight patients were enrolled of whom 27 were evaluable for efficacy. Patients received ibrutinib for a median of 21 months (range 7-67) prior to study enrollment. Fourteen patients (52%) have achieved U-MRD per protocol whereas 78% had at least one U-MRD evaluation. Seventeen patients (63%) have entered TFO after a median of 6.4 months on triplet therapy. Progression-free survival at 12 months was estimated at 95%. Grade ≥3 adverse events were hypertension 7%, diarrhea 4%, and increased ALT/AST 4%. CONCLUSIONS: This triplet approach utilizes the addition of U2 to ibrutinib as an MRD-driven time-limited therapy. This therapy was well tolerated and effective. TFO following this therapy appears durable in ongoing follow-up.

Phase 2 study of the safety and efficacy of umbralisib in patients with CLL who are intolerant to BTK or PI3Kδ inhibitor therapy.

Intolerance is the most common reason for kinase inhibitor (KI) discontinuation in chronic lymphocytic leukemia (CLL). Umbralisib, a novel highly selective phosphatidylinositol 3-kinase Î´ (PI3Kδ)/CK1ε inhibitor, is active and well tolerated in CLL patients. In this phase 2 trial (NCT02742090), umbralisib was initiated at 800 mg/d in CLL patients requiring therapy, who were intolerant to prior BTK inhibitor (BTKi) or PI3K inhibitor (PI3Ki) therapy, until progression or toxicity. Primary end point was progression-free survival (PFS). Secondary end points included time to treatment failure and safety. DNA was genotyped for CYP3A4, CYP3A5, and CYP2D6 polymorphisms. Fifty-one patients were enrolled (44 BTKi intolerant and 7 PI3Kδi intolerant); median age was 70 years (range, 48-96), with a median of 2 prior lines of therapy (range, 1-7), 24% had del17p and/or TP53 mutation, and 65% had unmutated IGHV. Most common adverse events (AEs) leading to prior KI discontinuation were rash (27%), arthralgia (18%), and atrial fibrillation (16%). Median PFS was 23.5 months (95% CI, 13.1-not estimable), with 58% of patients on umbralisib for a longer duration than prior KI. Most common (≥5%) grade ≥3 AEs on umbralisib (all causality) were neutropenia (18%), leukocytosis (14%), thrombocytopenia (12%), pneumonia (12%), and diarrhea (8%). Six patients (12%) discontinued umbralisib because of an AE. Eight patients (16%) had dose reductions and were successfully rechallenged. These are the first prospective data to confirm that switching from a BTKi or alternate PI3Ki to umbralisib in this BTKi- and PI3Ki-intolerant CLL population can result in durable well-tolerated responses.

Assessment of the Efficacy of Therapies Following Venetoclax Discontinuation in CLL Reveals BTK Inhibition as an Effective Strategy.

PURPOSE: Venetoclax-based therapy is a standard-of-care option in first-line and relapsed/refractory chronic lymphocytic leukemia (CLL). Patient management following venetoclax discontinuation remains nonstandard and poorly understood. EXPERIMENTAL DESIGN: To address this, we conducted a large international study to identify a cohort of 326 patients who discontinued venetoclax and have been subsequently treated. Coprimary endpoints were overall response rate (ORR) and progression-free survival for the post-venetoclax treatments stratified by treatment type [Bruton's tyrosine kinase inhibitor (BTKi), PI3K inhibitor (PI3Ki), and cellular therapies]. RESULTS: We identified patients with CLL who discontinued venetoclax in the first-line (4%) and relapsed/refractory settings (96%). Patients received a median of three therapies prior to venetoclax; 40% were BTKi naïve (n = 130), and 81% were idelalisib naïve (n = 263). ORR to BTKi was 84% (n = 44) in BTKi-naïve patients versus 54% (n = 30) in BTKi-exposed patients. We demonstrate therapy selection following venetoclax requires prior novel agent exposure consideration and discontinuation reasons. CONCLUSIONS: For BTKi-naïve patients, selection of covalently binding BTKis results in high ORR and durable remissions. For BTKi-exposed patients, covalent BTK inhibition is not effective in the setting of BTKi resistance. PI3Kis following venetoclax do not appear to result in durable remissions. We conclude that BTKi in naïve or previously responsive patients and cellular therapies following venetoclax may be the most effective strategies.See related commentary by Rogers, p. 3501.

A retrospective comparison of venetoclax alone or in combination with an anti-CD20 monoclonal antibody in R/R CLL.

Venetoclax (VEN) is approved for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) as monotherapy (VENmono) or in combination with rituximab. Whether VEN plus anti-CD20 (VENcombo) is superior to VENmono is unknown. We conducted a multicenter, retrospective cohort analysis comparing 321 CLL patients treated with VENmono vs VENcombo across the United States and the United Kingdom. We examined demographics, baseline characteristics, dosing, adverse events, response rates, and outcomes. The primary endpoints were progression-free survival (PFS) and overall survival (OS), estimated by Kaplan-Meier method, in patients treated with VENmono vs VENcombo. Univariate and bivariate analyses were performed with COX regression. Three hundred twenty-one CLL patients were included (3 median prior treatments, 78% prior ibrutinib). The overall response rates (ORRs) were similar (VENmono, 81% ORR, 34% complete remission [CR] vs VENcombo, 84% ORR, 32% CR). With a median follow-up of 13.4 months, no differences in PFS and OS were observed between the groups. In unadjusted analyses, the hazard ratios (HRs) for PFS and OS for VENmono vs VENcombo were HR 1.0 (95% confidence interval [CI], 0.6-1.8; P = .7) and HR 1.2 (95% CI, 0.6-2.3; P = .5), respectively. When adjusting for differences between the cohorts, the addition of an anti-CD20 antibody in combination with VEN did not impact PFS (HR, 1.0; 95% CI, 0.5-2.0; P = .9) or OS (HR, 1.1; 95% CI, 0.4-2.6; P = .8). We demonstrate comparable efficacy between VENmono and VENcombo in a heavily pretreated, high-risk, retrospective cohort, in terms of both response data and survival outcomes. Prospective studies are needed to validate these findings.

Tumor Lysis, Adverse Events, and Dose Adjustments in 297 Venetoclax-Treated CLL Patients in Routine Clinical Practice.

PURPOSE: Clinical trials of venetoclax reported negligible rates of clinical tumor lysis syndrome (TLS) in patients with chronic lymphocytic leukemia (CLL) when using an extended dose escalation schedule. We aimed to understand TLS prophylaxis, rates of select adverse events (AE), and impact of dosing modifications in routine clinical practice. EXPERIMENTAL DESIGN: This retrospective cohort study included 297 CLL venetoclax-treated patients outside of clinical trials in academic and community centers. Demographics, baseline disease characteristics, venetoclax dosing, TLS risk and prophylaxis, and AEs were collected. RESULTS: The group was 69% male, 96% had relapsed/refractory CLL, 45% had deletion chromosome 17p, 84% had unmutated IGHV, 80% received venetoclax monotherapy, and median age was 67. TLS risk was categorized as low (40%), intermediate (32%), or high (28%), and 62% had imaging prior to venetoclax initiation. Clinical TLS occurred in 2.7% of patients and laboratory TLS occurred in 5.7%. Pre-venetoclax TLS risk group and creatinine clearance independently predict TLS development in multivariable analysis. Grade 3/4 AEs included neutropenia (39.6%), thrombocytopenia (29.2%), infection (25%), neutropenic fever (7.9%), and diarrhea (6.9%). Twenty-two patients (7.4%) discontinued venetoclax due to an AE. Progression-free survival was similar regardless of number of dose interruptions, length of dose interruption, and stable venetoclax dose. CONCLUSIONS: These data provide insights into current use of venetoclax in clinical practice, including TLS rates observed in clinical practice. We identified opportunities for improved adherence to TLS risk stratification and prophylaxis, which may improve safety.

Real-world outcomes and management strategies for venetoclax-treated chronic lymphocytic leukemia patients in the United States.

Venetoclax is a BCL2 inhibitor approved for 17p-deleted relapsed/refractory chronic lymphocytic leukemia with activity following kinase inhibitors. We conducted a multicenter retrospective cohort analysis of patients with chronic lymphocytic leukemia treated with venetoclax to describe outcomes, toxicities, and treatment selection following venetoclax discontinuation. A total of 141 chronic lymphocytic leukemia patients were included (98% relapsed/refractory). Median age at venetoclax initiation was 67 years (range 37-91), median prior therapies was 3 (0-11), 81% unmutated IGHV, 45% del(17p), and 26.8% complex karyotype (≥ 3 abnormalities). Prior to venetoclax initiation, 89% received a B-cell receptor antagonist. For tumor lysis syndrome prophylaxis, 93% received allopurinol, 92% normal saline, and 45% rasburicase. Dose escalation to the maximum recommended dose of 400 mg daily was achieved in 85% of patients. Adverse events of interest included neutropenia in 47.4%, thrombocytopenia in 36%, tumor lysis syndrome in 13.4%, neutropenic fever in 11.6%, and diarrhea in 7.3%. The overall response rate to venetoclax was 72% (19.4% complete remission). With a median follow up of 7 months, median progression free survival and overall survival for the entire cohort have not been reached. To date, 41 venetoclax treated patients have discontinued therapy and 24 have received a subsequent therapy, most commonly ibrutinib. In the largest clinical experience of venetoclax-treated chronic lymphocytic leukemia patients, the majority successfully completed and maintained a maximum recommended dose. Response rates and duration of response appear comparable to clinical trial data. Venetoclax was active in patients with mutations known to confer ibrutinib resistance. Optimal sequencing of newer chronic lymphocytic leukemia therapies requires further study.

Toxicities and outcomes of 616 ibrutinib-treated patients in the United States: a real-world analysis.

Clinical trials that led to ibrutinib's approval for the treatment of chronic lymphocytic leukemia showed that its side effects differ from those of traditional chemotherapy. Reasons for discontinuation in clinical practice have not been adequately studied. We conducted a retrospective analysis of chronic lymphocytic leukemia patients treated with ibrutinib either commercially or on clinical trials. We aimed to compare the type and frequency of toxicities reported in either setting, assess discontinuation rates, and evaluate outcomes. This multicenter, retrospective analysis included ibrutinib-treated chronic lymphocytic leukemia patients at nine United States cancer centers or from the Connect® Chronic Lymphocytic Leukemia Registry. We examined demographics, dosing, discontinuation rates and reasons, toxicities, and outcomes. The primary endpoint was progression-free survival. Six hundred sixteen ibrutinib-treated patients were identified. A total of 546 (88%) patients were treated with the commercial drug. Clinical trial patients were younger (mean age 58 versus 61 years, P=0.01) and had a similar time from diagnosis to treatment with ibrutinib (mean 85 versus 87 months, P=0.8). With a median follow-up of 17 months, an estimated 41% of patients discontinued ibrutinib (median time to ibrutinib discontinuation was 7 months). Notably, ibrutinib toxicity was the most common reason for discontinuation in all settings. The median progression-free survival and overall survival for the entire cohort were 35 months and not reached (median follow-up 17 months), respectively. In the largest reported series on ibrutinib- treated chronic lymphocytic leukemia patients, we show that 41% of patients discontinued ibrutinib. Intolerance as opposed to chronic lymphocytic leukemia progression was the most common reason for discontinuation. Outcomes remain excellent and were not affected by line of therapy or whether patients were treated on clinical studies or commercially. These data strongly argue in favor of finding strategies to minimize ibrutinib intolerance so that efficacy can be further maximized. Future clinical trials should consider time-limited therapy approaches, particularly in patients achieving a complete response, in order to minimize ibrutinib exposure.