Effective Tumor Debulking with Ibrutinib Before Initiation of Venetoclax: Results from the CAPTIVATE Minimal Residual Disease and Fixed-Duration Cohorts.

PURPOSE: The phase II CAPTIVATE study investigated first-line treatment with ibrutinib plus venetoclax for chronic lymphocytic leukemia in two cohorts: minimal residual disease (MRD)-guided randomized treatment discontinuation (MRD cohort) and fixed duration (FD cohort). We report tumor debulking and tumor lysis syndrome (TLS) risk category reduction with three cycles of single-agent ibrutinib lead-in before initiation of venetoclax using pooled data from the MRD and FD cohorts. PATIENTS AND METHODS: In both cohorts, patients initially received three cycles of ibrutinib 420 mg/day then 12 cycles of ibrutinib plus venetoclax (5-week ramp-up to 400 mg/day). RESULTS: In the total population (N = 323), the following decreases from baseline to after ibrutinib lead-in were observed: percentage of patients with a lymph node diameter ≥5 cm decreased from 31% to 4%, with absolute lymphocyte count ≥25 × 109/L from 76% to 65%, with high tumor burden category for TLS risk from 23% to 2%, and with an indication for hospitalization (high TLS risk, or medium TLS risk and creatinine clearance <80 mL/minute) from 43% to 18%. Laboratory TLS per Howard criteria occurred in one patient; no clinical TLS was observed. CONCLUSIONS: Three cycles of ibrutinib lead-in before venetoclax initiation provides effective tumor debulking, decreases the TLS risk category and reduces the need for hospitalization for intensive monitoring for TLS.

Ibrutinib for Hospitalized Adults With Severe Coronavirus Disease 2019 Infection: Results of the Randomized, Double-Blind, Placebo-Controlled iNSPIRE Study.

Background: Few therapies are approved for hospitalized patients with severe coronavirus disease 2019 (COVID-19). Ibrutinib, a once-daily Bruton tyrosine kinase inhibitor, may mitigate COVID-19-induced lung damage by reducing inflammatory cytokines. The multicenter, randomized, double-blind phase 2 iNSPIRE study evaluated ibrutinib for prevention of respiratory failure in hospitalized patients with severe COVID-19. Methods: Adult patients with severe COVID-19 requiring hospitalization and supplemental oxygen but without respiratory failure were randomized 1:1 (stratified by remdesivir prescription) to ibrutinib 420 mg or placebo once daily for up to 28 days plus standard of care (SOC), including remdesivir and/or dexamethasone. Results: Forty-six patients were randomized to ibrutinib plus SOC (n = 22) or placebo plus SOC (n = 24). The primary endpoint (proportion of patients alive and without respiratory failure through day 28) was not met, with no statistically significant difference adjusting for remdesivir prescription (86% with ibrutinib plus SOC vs 79% with placebo plus SOC; adjusted difference, 5.8% [80% confidence interval, -9.2% to 20.4%]; P = .599). Secondary endpoints also showed no statistically significant improvement with ibrutinib plus SOC. Median treatment duration was 14 days for ibrutinib and placebo. Adverse events were similar with ibrutinib plus SOC vs placebo plus SOC (overall: 55% vs 50%; serious: 18% vs 13%) and were consistent with the known safety profile of ibrutinib. Conclusions: Addition of ibrutinib to SOC did not improve the proportion of patients alive and without respiratory failure through day 28 in hospitalized patients with severe COVID-19. Ibrutinib had a manageable safety profile, with similar safety to placebo. Clinical Trials Registration: NCT04375397.

Fixed-duration ibrutinib plus venetoclax for first-line treatment of CLL: primary analysis of the CAPTIVATE FD cohort.

CAPTIVATE (NCT02910583) is an international phase 2 study in patients aged ≤70 years with previously untreated chronic lymphocytic leukemia (CLL). Results from the cohort investigating fixed-duration (FD) treatment with ibrutinib plus venetoclax are reported. Patients received 3 cycles of ibrutinib lead-in then 12 cycles of ibrutinib plus venetoclax (oral ibrutinib [420 mg/d]; oral venetoclax [5-week ramp-up to 400 mg/d]). The primary endpoint was complete response (CR) rate. Hypothesis testing was performed for patients without del(17p) with prespecified analyses in all treated patients. Secondary endpoints included undetectable minimal residual disease (uMRD) rates, progression-free survival (PFS), overall survival (OS), and safety. Of the 159 patients enrolled and treated, 136 were without del(17p). The median time on study was 27.9 months, and 92% of patients completed all planned treatment. The primary endpoint was met, with a CR rate of 56% (95% confidence interval [CI], 48-64) in patients without del(17p), significantly higher than the prespecified 37% minimum rate (P < .0001). In the all-treated population, CR rate was 55% (95% CI, 48-63); best uMRD rates were 77% (peripheral blood [PB]) and 60% (bone marrow [BM]); 24-month PFS and OS rates were 95% and 98%, respectively. At baseline, 21% of patients were in the high tumor burden category for tumor lysis syndrome (TLS) risk; after ibrutinib lead-in, only 1% remained in this category. The most common grade ≥3 adverse events (AEs) were neutropenia (33%) and hypertension (6%). First-line ibrutinib plus venetoclax represents the first all-oral, once-daily, chemotherapy-free FD regimen for patients with CLL. FD ibrutinib plus venetoclax achieved deep, durable responses and promising PFS, including in patients with high-risk features.

Ibrutinib Plus Venetoclax for First-Line Treatment of Chronic Lymphocytic Leukemia: Primary Analysis Results From the Minimal Residual Disease Cohort of the Randomized Phase II CAPTIVATE Study.

PURPOSE: CAPTIVATE (NCT02910583), a randomized phase II study, evaluates minimal residual disease (MRD)-guided treatment discontinuation following completion of first-line ibrutinib plus venetoclax treatment in patients with chronic lymphocytic leukemia (CLL). METHODS: Previously untreated CLL patients age < 70 years received three cycles of ibrutinib and then 12 cycles of combined ibrutinib plus venetoclax. Patients in the MRD cohort who met the stringent random assignment criteria for confirmed undetectable MRD (Confirmed uMRD) were randomly assigned 1:1 to double-blind placebo or ibrutinib; patients without Confirmed uMRD (uMRD Not Confirmed) were randomly assigned 1:1 to open-label ibrutinib or ibrutinib plus venetoclax. Primary end point was 1-year disease-free survival (DFS) rate with placebo versus ibrutinib in the Confirmed uMRD population. Secondary end points included response rates, uMRD, and safety. RESULTS: One hundred sixty-four patients initiated three cycles of ibrutinib lead-in. After 12 cycles of ibrutinib plus venetoclax, best uMRD response rates were 75% (peripheral blood) and 68% (bone marrow). Patients with Confirmed uMRD were randomly assigned to receive placebo (n = 43) or ibrutinib (n = 43); patients with uMRD Not Confirmed were randomly assigned to ibrutinib (n = 31) or ibrutinib plus venetoclax (n = 32). Median follow-up was 31.3 months. One-year DFS rate was not significantly different between placebo (95%) and ibrutinib (100%; arm difference: 4.7% [95% CI, -1.6 to 10.9]; P = .15) in the Confirmed uMRD population. After ibrutinib lead-in tumor debulking, 36 of 40 patients (90%) with high tumor lysis syndrome risk at baseline shifted to medium or low tumor lysis syndrome risk categories. Adverse events were most frequent during the first 6 months of ibrutinib plus venetoclax and generally decreased over time. CONCLUSION: The 1-year DFS rate of 95% in placebo-randomly assigned patients with Confirmed uMRD suggests the potential for fixed-duration treatment with this all-oral, once-daily, chemotherapy-free regimen in first-line CLL.

Effects of ibrutinib on in vitro platelet aggregation in blood samples from healthy donors and donors with platelet dysfunction.

Background: Ibrutinib, a first-in-class, once-daily inhibitor of Bruton's tyrosine kinase (BTK), is approved in the US and EU for the treatment of various B-cell malignancies. In clinical studies, BTK inhibitors have been associated with increased bleeding risk, which may result from BTK inhibition in platelets.Methods: To better understand the mechanism of ibrutinib in bleeding events, we isolated platelet-rich plasma from healthy donors (n = 8) and donors with conditions associated with impaired platelet function or with potentially increased bleeding risk (on hemodialysis, taking aspirin, or taking warfarin; n = 8 each cohort) and used light transmission aggregometry to assess platelet aggregation in vitro after exposure to escalating concentrations of ibrutinib, spanning and exceeding the pharmacologic range of clinical exposure.Results: Platelet aggregation was induced by agonists of 5 major platelet receptors: adenosine diphosphate (ADP), thrombin receptor-activating peptide 6 (TRAP6), ristocetin, collagen, or arachidonic acid (AA). Platelet aggregation induced by ADP, TRAP6, ristocetin, and AA was not meaningfully inhibited by the maximal concentrations of ibrutinib (10 µM). In contrast, collagen-induced platelet aggregation was dose-dependently inhibited by ibrutinib in all donor cohorts (maximum aggregation % with 10 µM ibrutinib, -64% to -83% of agonist activity compared to control agonist samples but without ibrutinib).Conclusion: These results confirm prior reports and support a mechanistic role for the inhibition of collagen-induced platelet aggregation in bleeding events among susceptible individuals receiving ibrutinib therapy.

Long-Term Studies Assessing Outcomes of Ibrutinib Therapy in Patients With Del(11q) Chronic Lymphocytic Leukemia.

BACKGROUND: Certain genomic features, such as del(11q), expression of unmutated immunoglobulin heavy-chain variable region (IGHV) gene, or complex karyotype, predict poorer outcomes to chemotherapy in patients with chronic lymphocytic leukemia (CLL). PATIENTS AND METHODS: We examined the pooled long-term follow-up data from PCYC-1115 (RESONATE-2), PCYC-1112 (RESONATE), and CLL3001 (HELIOS), comprising a total of 1238 subjects, to determine the prognostic significance of these markers in patients treated with ibrutinib. RESULTS: With a median follow-up of 47 months, ibrutinib-treated patients had longer progression-free survival (PFS) than patients treated in the comparator arm, regardless of genomic risk factors. Among patients treated with ibrutinib, we found that high-risk genomic features were not associated with shorter PFS (63-75% across all subgroups at 42 months) or overall survival (79-83% across all subgroups at 42 months). Surprisingly, we observed that ibrutinib-treated patients with del(11q) actually had a significantly longer PFS than ibrutinib-treated patients without del(11q) (42-month PFS rate 70% vs. 65%, P = .02). CONCLUSION: These analyses not only demonstrate that genomic risk factors previously associated with poor outcomes lose their adverse prognostic significance but also that del(11q) can be associated with a superior PFS with ibrutinib therapy.

Outcomes with ibrutinib by line of therapy and post-ibrutinib discontinuation in patients with chronic lymphocytic leukemia: Phase 3 analysis.

The efficacy of ibrutinib has been demonstrated in patients with chronic lymphocytic leukemia (CLL), including as first-line therapy. However, outcomes after ibrutinib discontinuation have previously been limited to higher-risk populations with relapsed/refractory (R/R) disease. The objective of this study was to evaluate outcomes of ibrutinib-treated patients based on prior lines of therapy, including after ibrutinib discontinuation. Data were analyzed from two multicenter phase 3 studies of single-agent ibrutinib: RESONATE (PCYC-1112) in patients with R/R CLL and RESONATE-2 (PCYC-1115) in patients with treatment-naive (TN) CLL without del(17p). This integrated analysis included 271 ibrutinib-treated non-del(17p) patients with CLL (136 TN and 135 R/R). Median progression-free survival (PFS) was not reached for subgroups with 0 and 1/2 prior therapies but was 40.6 months for patients with ≥3 therapies (median follow-up: TN, 36 months; R/R, 44 months). Median overall survival (OS) was not reached in any subgroup. Overall response rate (ORR) was 92% in TN and 92% in R/R, with depth of response increasing over time. Adverse events (AEs) and ibrutinib discontinuation due to AEs were similar between patient groups. Most patients (64%) remain on treatment. OS following discontinuation was 9.3 months in R/R patients (median follow-up 18 months, n = 51) and was not reached in TN patients (median follow-up 10 months, n = 30). In this integrated analysis, ibrutinib was associated with favorable PFS and OS, and high ORR regardless of prior therapies in patients with CLL. The best outcomes following ibrutinib discontinuation were for patients receiving ibrutinib in earlier lines of therapy.

Characterizing the kinetics of lymphocytosis in patients with chronic lymphocytic leukemia treated with single-agent ibrutinib.

Increased absolute lymphocyte count (ALC) is a key feature of chronic lymphocytic leukemia (CLL) but is also observed during treatment with B-cell receptor pathway inhibitors including ibrutinib, a first-in-class inhibitor of Bruton's tyrosine kinase. In patients with CLL treated with single-agent ibrutinib in two multicenter, open-label, randomized, phase 3 studies (RESONATE-2, NCT01722487; RESONATE, NCT01578707), lymphocytosis was observed in 77 of 136 (57%) patients treated in first-line and 133 of 195 (69%) relapsed/refractory patients. On treatment, lymphocytosis resolved in 95% of patients in the first-line and 94% in the relapsed/refractory setting. The median duration of lymphocytosis was 12 and 14 weeks in the first-line and relapsed/refractory settings, respectively. Lymphocytosis is a common and predictable pharmacodynamic effect of ibrutinib treatment, and in the absence of other signs of progression, does not represent disease progression. Lymphocytosis resolves in the majority of patients and does not require interruption or discontinuation of ibrutinib therapy.

Use of anticoagulants and antiplatelet in patients with chronic lymphocytic leukaemia treated with single-agent ibrutinib.

Bleeding events have been observed among a subgroup of chronic lymphocytic leukaemia (CLL) patients treated with ibrutinib. We analysed data from two studies of single-agent ibrutinib to better characterize bleeding events and pattern of anticoagulation and antiplatelet use. Among 327 ibrutinib-treated patients, concomitant anticoagulation (11%) or antiplatelet use (34%) was common, but major bleeding was infrequent (2%). Bleeding events were primarily grade 1, and infrequently (1%) led to discontinuation. Among 175 patients receiving concomitant anticoagulant or antiplatelet agents, 5 had major bleeding events (3%). These events were typically observed in conjunction with other factors, such as coexisting medical conditions and/or concurrent medications.