Long-term follow-up of the RESONATE phase 3 trial of ibrutinib vs ofatumumab.

Ibrutinib, a once-daily oral inhibitor of Bruton tyrosine kinase, has greatly improved outcomes for patients with chronic lymphocytic leukemia (CLL). The phase 3 RESONATE trial, which compared single-agent ibrutinib to ofatumumab in high-risk, relapsed patients with CLL, provided support for approval of ibrutinib in the United States and Europe. We describe long-term follow-up of patients treated in RESONATE, where continued superiority of progression-free survival (PFS) (hazard ratio [HR], 0.133; 95% confidence interval [CI], 0.099-0.178) was observed. Overall survival benefit continues (HR, 0.591; 95% CI, 0.378-0.926), although with decreased magnitude relative to that seen before crossover to ibrutinib was implemented for patients on ofatumumab (HR, 0.426; 95% CI, 0.220-0.823). Notably, overall response to ibrutinib increased over time, with 91% of patients attaining a response. The PFS benefit with ibrutinib was independent of baseline risk factors, although patients with ≥2 prior therapies had shorter PFS than those with <2 prior therapies, and the presence of TP53 or SF3B1 mutations showed a trend toward shorter PFS vs without these factors. Median duration of ibrutinib was 41 months, with 46% remaining on treatment at a median follow-up of 44 months. Grade ≥3 adverse events generally decreased over time, causing only a small proportion of patients to cease therapy. Ibrutinib was discontinued due to progressive disease in 27% of patients. This long-term study provides support for sustained efficacy and safety of ibrutinib in relapsed/refractory CLL and consideration of study provisions that allow crossover to investigational therapy when benefit has been clearly demonstrated. This trial was registered at www.clinicaltrials.gov as #NCT01578707.

Single-agent ibrutinib in treatment-naïve and relapsed/refractory chronic lymphocytic leukemia: a 5-year experience.

We previously reported durable responses and manageable safety of ibrutinib from a 3-year follow-up of treatment-naïve (TN) older patients (≥65 years of age) and relapsed/refractory (R/R) patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). We now report on long-term efficacy and safety with median follow-up of 5 years in this patient population with TN (N = 31) and R/R (N = 101) CLL/SLL. With the current 5-year follow-up, ibrutinib continues to yield a high overall response rate of 89%, with complete response rates increasing over time to 29% in TN patients and 10% in R/R patients. The median progression-free survival (PFS) was not reached in TN patients. The 5-year PFS rate was 92% in TN patients and 44% in R/R patients. Median PFS in R/R patients was 51 months; in those with del(11q), del(17p), and unmutated IGHV, it was 51, 26, and 43 months, respectively, demonstrating long-term efficacy of ibrutinib in some high-risk subgroups. Survival outcomes were less robust for R/R patients with del(17p) and those who received more prior therapies. The onset of grade ≥3 cytopenias, such as neutropenia and thrombocytopenia, decreased over time. Treatment--limiting adverse events were more frequent during the first year compared with subsequent periods. These results demonstrate sustained efficacy and acceptable tolerability of ibrutinib over an extended time, providing the longest experience for Bruton tyrosine kinase inhibitor treatment in patients with CLL/SLL. These trials were registered at www.clinicaltrials.gov as #NCT01105247 and #NCT01109069.

Ibrutinib plus obinutuzumab versus chlorambucil plus obinutuzumab in first-line treatment of chronic lymphocytic leukaemia (iLLUMINATE): a multicentre, randomised, open-label, phase 3 trial.

BACKGROUND: Both single-agent ibrutinib and chlorambucil plus obinutuzumab have shown superior efficacy to chlorambucil monotherapy and are standard first-line treatments in chronic lymphocytic leukaemia. We compared the efficacy of the combination of ibrutinib plus obinutuzumab with chlorambucil plus obinutuzumab in first-line chronic lymphocytic leukaemia or small lymphocytic lymphoma. METHODS: iLLUMINATE is a multicentre, randomised, open-label, phase 3 trial done at 74 academic and community hospitals in Australia, Canada, Israel, New Zealand, Russia, Turkey, the EU, and the USA in patients with previously untreated chronic lymphocytic leukaemia or small lymphocytic lymphoma, either aged 65 years or older or younger than 65 years with coexisting conditions. Patients were randomly assigned (1:1) using a blocked randomisation schedule, stratified by Eastern Cooperative Oncology Group performance status and cytogenetics, to receive ibrutinib plus obinutuzumab (oral ibrutinib [420 mg once daily continuously] combined with intravenous obinutuzumab [100 mg on day 1, 900 mg on day 2, 1000 mg on day 8, and 1000 mg on day 15 of cycle 1 and on day 1 of subsequent 28-day cycles, for a total of six cycles]) or chlorambucil plus obinutuzumab (oral chlorambucil [0·5 mg/kg bodyweight on days 1 and 15 of each 28-day cycle for six cycles] combined with the same obinutuzumab regimen). Allocation concealment was achieved using an interactive web response system. Patients and investigators were not masked to treatment assignment. The primary endpoint was progression-free survival assessed by a masked independent review committee in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov (NCT02264574), and patient enrolment is complete. FINDINGS: Between Oct 6, 2014, and Oct 12, 2015, 229 patients were enrolled and randomly assigned to receive ibrutinib plus obinutuzumab (n=113) or chlorambucil plus obinutuzumab (n=116). After a median follow-up of 31·3 months (IQR 29·4-33·2), median progression-free survival was significantly longer in the ibrutinib plus obinutuzumab group (median not reached [95% CI 33·6-non-estimable]) than in the chlorambucil plus obinutuzumab group (19·0 months [15·1-22·1]; hazard ratio 0·23; 95% CI 0·15-0·37; p<0·0001). Estimated 30-month progression-free survival was 79% (95% CI 70-85) in the ibrutinib plus obinutuzumab group and 31% (23-40) in the chlorambucil plus obinutuzumab group. The most common grade 3 or 4 adverse events in both groups were neutropenia and thrombocytopenia. Serious adverse events occurred in 65 (58%) of 113 patients treated with ibrutinib plus obinutuzumab and 40 (35%) of 115 patients treated with chlorambucil plus obinutuzumab. Ibrutinib or chlorambucil treatment-related deaths were reported in one (1%) of 113 patients in the ibrutinib plus obinutuzumab group (sudden death) and one (1%) of 115 patients in the chlorambucil plus obinutuzumab group (neuroendocrine carcinoma of the skin). INTERPRETATION: Ibrutinib plus obinutuzumab is an efficacious and safe chemotherapy-free combination treatment in previously untreated patients with chronic lymphocytic leukaemia or small lymphocytic lymphoma independent of high-risk features and provides an alternative first-line treatment option for these patients. FUNDING: Pharmacyclics LLC, an AbbVie Company, and Janssen Research and Development.

Ibrutinib for chronic graft-versus-host disease after failure of prior therapy.

Chronic graft-versus-host disease (cGVHD) is a serious complication of allogeneic stem cell transplantation with few effective options available after failure of corticosteroids. B and T cells play a role in the pathophysiology of cGVHD. Ibrutinib inhibits Bruton tyrosine kinase in B cells and interleukin-2-inducible T-cell kinase in T cells. In preclinical models, ibrutinib reduced severity of cGVHD. This multicenter, open-label study evaluated the safety and efficacy of ibrutinib in patients with active cGVHD with inadequate response to corticosteroid-containing therapies. Forty-two patients who had failed 1 to 3 prior treatments received ibrutinib (420 mg) daily until cGVHD progression. The primary efficacy end point was cGVHD response based on 2005 National Institutes of Health criteria. At a median follow-up of 13.9 months, best overall response was 67%; 71% of responders showed a sustained response for ≥20 weeks. Responses were observed across involved organs evaluated. Most patients with multiple cGVHD organ involvement had a multiorgan response. Median corticosteroid dose in responders decreased from 0.29 mg/kg per day at baseline to 0.12 mg/kg per day at week 49; 5 responders discontinued corticosteroids. The most common adverse events were fatigue, diarrhea, muscle spasms, nausea, and bruising. Plasma levels of soluble factors associated with inflammation, fibrosis, and cGVHD significantly decreased over time with ibrutinib. Ibrutinib resulted in clinically meaningful responses with acceptable safety in patients with ≥1 prior treatments for cGVHD. Based on these results, ibrutinib was approved in the United States for treatment of adult patients with cGVHD after failure of 1 or more lines of systemic therapy. This trial was registered at www.clinicaltrials.gov as #NCT02195869.

Impact of ibrutinib dose adherence on therapeutic efficacy in patients with previously treated CLL/SLL.

Ibrutinib, an oral inhibitor of Bruton's tyrosine kinase (BTK), at a once-daily dose of 420 mg achieved BTK active-site occupancy in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) that was maintained at 24 hours. It is unknown if intermittent interruption of ibrutinib therapy contributes to altered clinical outcomes. We therefore evaluated the effect of ibrutinib dose adherence on patient outcomes in the phase 3 RESONATE trial. The overall mean dose intensity (DI) was 95% with median treatment duration of ∼9 months. Pharmacokinetic assessment of ibrutinib exposure at 420-mg dose suggested similar exposure regardless of patient weight or age. As assessed by independent review committee, patients with higher DI experienced longer median progression-free survival (PFS) compared with those with lower DI regardless of del17p and/or TP53 status. Of 79 patients requiring a drug hold, treatment was restarted at the original dose in 73 (92%) patients. Mean duration of a missed-dose event was 18.7 days (range, 8-56). Patients missing ≥8 consecutive days of ibrutinib had a shorter median PFS vs those missing <8 days (10.9 months vs not reached). These results support sustained adherence to once-daily ibrutinib dosing at 420 mg as clinically feasible to achieve optimal outcomes in patients with previously treated CLL. The trial was registered at www.clinicaltrials.gov as #NCT01578707.

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.

Evaluation of 230 patients with relapsed/refractory deletion 17p chronic lymphocytic leukaemia treated with ibrutinib from 3 clinical trials.

Patients with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) with deletion 17p [del(17p)] have poor outcomes with chemoimmunotherapy. Ibrutinib is indicated for the treatment of CLL/SLL, including del(17p) CLL/SLL, and allows for treatment without chemotherapy. This integrated analysis was performed to evaluate outcomes in 230 patients with relapsed/refractory del(17p) CLL/SLL from three ibrutinib studies. With a median of 2 prior therapies (range, 1-12), 18% and 79% of evaluable patients had del(11q) or unmutated IGHV, respectively. With a median follow-up of 28 months, overall response rate was 85% and estimated 30-month progression-free and overall survival rates were 57% [95% confidence interval (CI) 50-64] and 69% (95% CI 61-75), respectively. Patients with normal lactate dehydrogenase or no bulky disease had the most favourable survival outcomes. Sustained haematological improvements in haemoglobin, platelet count and absolute neutrophil count occurred in 61%, 67% and 70% of patients with baseline cytopenias, respectively. New onset severe cytopenias and infections decreased in frequency over time. Progression-free and overall survival with ibrutinib surpass those of other therapies for patients with del(17p) CLL/SLL. These results provide further evidence of the robust clinical activity of ibrutinib in difficult-to-treat CLL/SLL populations.

Ibrutinib as Initial Therapy for Patients with Chronic Lymphocytic Leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) primarily affects older persons who often have coexisting conditions in addition to disease-related immunosuppression and myelosuppression. We conducted an international, open-label, randomized phase 3 trial to compare two oral agents, ibrutinib and chlorambucil, in previously untreated older patients with CLL or small lymphocytic lymphoma. METHODS: We randomly assigned 269 previously untreated patients who were 65 years of age or older and had CLL or small lymphocytic lymphoma to receive ibrutinib or chlorambucil. The primary end point was progression-free survival as assessed by an independent review committee. RESULTS: The median age of the patients was 73 years. During a median follow-up period of 18.4 months, ibrutinib resulted in significantly longer progression-free survival than did chlorambucil (median, not reached vs. 18.9 months), with a risk of progression or death that was 84% lower with ibrutinib than that with chlorambucil (hazard ratio, 0.16; P<0.001). Ibrutinib significantly prolonged overall survival; the estimated survival rate at 24 months was 98% with ibrutinib versus 85% with chlorambucil, with a relative risk of death that was 84% lower in the ibrutinib group than in the chlorambucil group (hazard ratio, 0.16; P=0.001). The overall response rate was higher with ibrutinib than with chlorambucil (86% vs. 35%, P<0.001). The rates of sustained increases from baseline values in the hemoglobin and platelet levels were higher with ibrutinib. Adverse events of any grade that occurred in at least 20% of the patients receiving ibrutinib included diarrhea, fatigue, cough, and nausea; adverse events occurring in at least 20% of those receiving chlorambucil included nausea, fatigue, neutropenia, anemia, and vomiting. In the ibrutinib group, four patients had a grade 3 hemorrhage and one had a grade 4 hemorrhage. A total of 87% of the patients in the ibrutinib group are continuing to take ibrutinib. CONCLUSIONS: Ibrutinib was superior to chlorambucil in previously untreated patients with CLL or small lymphocytic lymphoma, as assessed by progression-free survival, overall survival, response rate, and improvement in hematologic variables. (Funded by Pharmacyclics and others; RESONATE-2 ClinicalTrials.gov number, NCT01722487.).

Single-agent ibrutinib versus chemoimmunotherapy regimens for treatment-naïve patients with chronic lymphocytic leukemia: A cross-trial comparison of phase 3 studies.

Chemoimmunotherapy (CIT) and targeted therapy with single-agent ibrutinib are both recommended first-line treatments for chronic lymphocytic leukemia (CLL), although their outcomes have not been directly compared. Using ibrutinib data from the RESONATE-2 (PCYC-1115/1116) study conducted in patients ≥65 years without del(17p), we performed a cross-trial comparison with CIT data from published phase 3 studies in first-line treatment of CLL. Progression-free survival (PFS), overall survival (OS), and safety data for ibrutinib (median follow-up 35.7 months) were evaluated alongside available CIT data. CIT regimens included: fludarabine + cyclophosphamide + rituximab (CLL8, CLL10), bendamustine + rituximab (CLL10), obinutuzumab + chlorambucil and rituximab + chlorambucil (CLL11), and ofatumumab + chlorambucil (COMPLEMENT-1). Median age across studies was 61-74 years, with older populations receiving ibrutinib, obinutuzumab + chlorambucil, or rituximab + chlorambucil. Median follow-up varied across studies/regimens (range 14.5-37.4 months). Among all patients, PFS appeared longer with ibrutinib relative to CIT and OS appeared comparable. Relative to CIT studies that similarly excluded patients with del(17p) (CLL10) or enrolled older/less-fit patients (CLL11), PFS appeared favorable for ibrutinib in high-risk subgroups, including advanced disease, bulky lymph nodes, unmutated IGHV status, and presence of del(11q). Grade ≥ 3 infections ranged from 9% (ofatumumab + chlorambucil) to 40% (fludarabine + cyclophosphamide + rituximab), and was 25% with ibrutinib. Grade ≥ 3 neutropenia was 12% for ibrutinib and 26%-84% for CIT. Although definitive conclusions cannot be made due to inherent limitations of cross-trial comparisons, this report suggests that ibrutinib has a favorable benefit/risk profile and may potentially eliminate the need for chemotherapy in some patients. Randomized, comparative studies are needed to support these findings.

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.

Resistance mechanisms for the Bruton's tyrosine kinase inhibitor ibrutinib.

BACKGROUND: Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase (BTK) and is effective in chronic lymphocytic leukemia (CLL). Resistance to irreversible kinase inhibitors and resistance associated with BTK inhibition have not been characterized. Although only a small proportion of patients have had a relapse during ibrutinib therapy, an understanding of resistance mechanisms is important. We evaluated patients with relapsed disease to identify mutations that may mediate ibrutinib resistance. METHODS: We performed whole-exome sequencing at baseline and the time of relapse on samples from six patients with acquired resistance to ibrutinib therapy. We then performed functional analysis of identified mutations. In addition, we performed Ion Torrent sequencing for identified resistance mutations on samples from nine patients with prolonged lymphocytosis. RESULTS: We identified a cysteine-to-serine mutation in BTK at the binding site of ibrutinib in five patients and identified three distinct mutations in PLCγ2 in two patients. Functional analysis showed that the C481S mutation of BTK results in a protein that is only reversibly inhibited by ibrutinib. The R665W and L845F mutations in PLCγ2 are both potentially gain-of-function mutations that lead to autonomous B-cell-receptor activity. These mutations were not found in any of the patients with prolonged lymphocytosis who were taking ibrutinib. CONCLUSIONS: Resistance to the irreversible BTK inhibitor ibrutinib often involves mutation of a cysteine residue where ibrutinib binding occurs. This finding, combined with two additional mutations in PLCγ2 that are immediately downstream of BTK, underscores the importance of the B-cell-receptor pathway in the mechanism of action of ibrutinib in CLL. (Funded by the National Cancer Institute and others.).

Ibrutinib versus ofatumumab in previously treated chronic lymphoid leukemia.

BACKGROUND: In patients with chronic lymphoid leukemia (CLL) or small lymphocytic lymphoma (SLL), a short duration of response to therapy or adverse cytogenetic abnormalities are associated with a poor outcome. We evaluated the efficacy of ibrutinib, a covalent inhibitor of Bruton's tyrosine kinase, in patients at risk for a poor outcome. METHODS: In this multicenter, open-label, phase 3 study, we randomly assigned 391 patients with relapsed or refractory CLL or SLL to receive daily ibrutinib or the anti-CD20 antibody ofatumumab. The primary end point was the duration of progression-free survival, with the duration of overall survival and the overall response rate as secondary end points. RESULTS: At a median follow-up of 9.4 months, ibrutinib significantly improved progression-free survival; the median duration was not reached in the ibrutinib group (with a rate of progression-free survival of 88% at 6 months), as compared with a median of 8.1 months in the ofatumumab group (hazard ratio for progression or death in the ibrutinib group, 0.22; P<0.001). Ibrutinib also significantly improved overall survival (hazard ratio for death, 0.43; P=0.005). At 12 months, the overall survival rate was 90% in the ibrutinib group and 81% in the ofatumumab group. The overall response rate was significantly higher in the ibrutinib group than in the ofatumumab group (42.6% vs. 4.1%, P<0.001). An additional 20% of ibrutinib-treated patients had a partial response with lymphocytosis. Similar effects were observed regardless of whether patients had a chromosome 17p13.1 deletion or resistance to purine analogues. The most frequent nonhematologic adverse events were diarrhea, fatigue, pyrexia, and nausea in the ibrutinib group and fatigue, infusion-related reactions, and cough in the ofatumumab group. CONCLUSIONS: Ibrutinib, as compared with ofatumumab, significantly improved progression-free survival, overall survival, and response rate among patients with previously treated CLL or SLL. (Funded by Pharmacyclics and Janssen; RESONATE ClinicalTrials.gov number, NCT01578707.).

The Bruton tyrosine kinase inhibitor ibrutinib with chemoimmunotherapy in patients with chronic lymphocytic leukemia.

The safety and efficacy of ibrutinib, an oral inhibitor of Bruton tyrosine kinase, were evaluated with chemoimmunotherapy (CIT) in a multicenter phase 1b study. Patients with relapsed/refractory chronic lymphocytic leukemia received bendamustine and rituximab (BR) or fludarabine, cyclophosphamide, and rituximab (FCR) for up to 6 cycles with daily ibrutinib (420 mg) until progressive disease or unacceptable toxicity. Enrollment to FCR-ibrutinib closed early due to a lack of fludarabine-naïve previously treated patients. No patients treated with BR-ibrutinib (n = 30) or FCR-ibrutinib (n = 3) experienced prolonged hematologic toxicity in cycle 1 (primary end point). Tolerability was as expected with either CIT or single-agent ibrutinib. The overall response rate (ORR) with BR-ibrutinib was 93.3%, including 16.7% complete responses (CRs) initially, which increased to 40% with the extension period. Including 1 patient with partial response with lymphocytosis, the best ORR was 96.7%. Sixteen of 21 patients with baseline cytopenias had sustained hematologic improvement. At 12 and 36 months, 86.3% and 70.3% remained progression-free, respectively. All 3 patients treated with ibrutinib-FCR achieved CR. Ibrutinib may enhance CIT efficacy without additive toxicities, providing the rationale for studying this combination in an ongoing phase 3 trial. The study is registered to www.clinicaltrials.gov as #NCT01292135.

Three-year follow-up of treatment-naïve and previously treated patients with CLL and SLL receiving single-agent ibrutinib.

Ibrutinib is an orally administered inhibitor of Bruton tyrosine kinase that antagonizes B-cell receptor, chemokine, and integrin-mediated signaling. In early-phase studies, ibrutinib demonstrated high response rates and prolonged progression-free survival (PFS) in chronic lymphocytic leukemia (CLL). The durable responses observed with ibrutinib relate in part to a modest toxicity profile that allows the majority of patients to receive continuous therapy for an extended period. We report on median 3-year follow-up of 132 patients with symptomatic treatment-naïve and relapsed/refractory CLL or small lymphocytic lymphoma. Longer treatment with ibrutinib was associated with improvement in response quality over time and durable remissions. Toxicity with longer follow-up diminished with respect to occurrence of grade 3 or greater cytopenias, fatigue, and infections. Progression remains uncommon, occurring primarily in some patients with relapsed del(17)(p13.1) and/or del(11)(q22.3) disease. Treatment-related lymphocytosis remains largely asymptomatic even when persisting >1 year and does not appear to alter longer-term PFS and overall survival compared with patients with partial response or better. Collectively, these data provide evidence that ibrutinib controls CLL disease manifestations and is well tolerated for an extended period; this information can help direct potential treatment options for different subgroups to diminish the long-term risk of relapse.

Safety and activity of BTK inhibitor ibrutinib combined with ofatumumab in chronic lymphocytic leukemia: a phase 1b/2 study.

Ibrutinib represents a therapeutic advance in chronic lymphocytic leukemia (CLL) but as monotherapy produces few complete remissions in previously treated patients. Anti-CD20 antibodies have improved response and progression-free survival (PFS) when combined with chemotherapy. We evaluated the safety and activity of adding ofatumumab to ibrutinib in 3 different administration sequences. Patients with CLL/small lymphocytic lymphoma (SLL), prolymphocytic leukemia, or Richter's transformation who failed ≥2 prior therapies were enrolled. Patients received ibrutinib 420 mg daily and 12 doses of ofatumumab 300/2000 mg in 3 schedules: ibrutinib lead-in (group 1; n = 27), concurrent start (group 2; n = 20), or ofatumumab lead-in (group 3; n = 24). Seventy-one patients were treated; most had high-risk disease including del(17)(p13.1) (44%) or del(11)(q22.3) (31%). The most frequent adverse events (any grade) were diarrhea (70%), infusion-related reaction (45%), and peripheral sensory neuropathy (44%). Overall response rates in CLL/SLL patients (n = 66) were 100%, 79%, and 71% in groups 1, 2, and 3, respectively. Estimated 12-month PFSs for all patients were 89%, 85%, and 75%, respectively. Four patients in group 3 progressed prior to receiving ibrutinib. This study demonstrates the tolerability and clinical activity of this combination with quicker time to best response than single-agent ibrutinib and with durable responses. This trial was registered at www.clinicaltrials.gov as #NCT01217749.

Characterization of atrial fibrillation adverse events reported in ibrutinib randomized controlled registration trials.

The first-in-class Bruton's tyrosine kinase inhibitor ibrutinib has proven clinical benefit in B-cell malignancies; however, atrial fibrillation (AF) has been reported in 6-16% of ibrutinib patients. We pooled data from 1505 chronic lymphocytic leukemia and mantle cell lymphoma patients enrolled in four large, randomized, controlled studies to characterize AF with ibrutinib and its management. AF incidence was 6.5% [95% Confidence Interval (CI): 4.8, 8.5] for ibrutinib at 16.6-months versus 1.6% (95%CI: 0.8, 2.8) for comparator and 10.4% (95%CI: 8.4, 12.9) at the 36-month follow up; estimated cumulative incidence: 13.8% (95%CI: 11.2, 16.8). Ibrutinib treatment, prior history of AF and age 65 years or over were independent risk factors for AF. Multiple AF events were more common with ibrutinib (44.9%; comparator, 16.7%) among patients with AF. Most (85.7%) patients with AF did not discontinue ibrutinib, and more than half received common anticoagulant/antiplatelet medications on study. Low-grade bleeds were more frequent with ibrutinib, but serious bleeds were uncommon (ibrutinib, 2.9%; comparator, 2.0%). Although the AF rate among older non-trial patients with comorbidities is likely underestimated by this dataset, these results suggest that AF among clinical trial patients is generally manageable without ibrutinib discontinuation (clinicaltrials.gov identifier: 01578707, 01722487, 01611090, 01646021).

Ibrutinib for patients with relapsed or refractory chronic lymphocytic leukaemia with 17p deletion (RESONATE-17): a phase 2, open-label, multicentre study.

BACKGROUND: The TP53 gene, encoding tumour suppressor protein p53, is located on the short arm of chromosome 17 (17p). Patients with 17p deletion (del17p) chronic lymphocytic leukaemia have poor responses and survival after chemoimmunotherapy. We assessed the activity and safety of ibrutinib, an oral covalent inhibitor of Bruton's tyrosine kinase, in relapsed or refractory patients with del17p chronic lymphocytic leukaemia or small lymphocytic lymphoma. METHODS: We did a multicentre, international, open-label, single-arm study at 40 sites in the USA, Canada, Europe, Australia, and New Zealand. Patients (age ≥18 years) with previously treated del17p chronic lymphocytic leukaemia or small lymphocytic lymphoma received oral ibrutinib 420 mg once daily until progressive disease or unacceptable toxicity. The primary endpoint was overall response in the all-treated population per International Workshop on Chronic Lymphocytic Leukaemia 2008 response criteria modified for treatment-related lymphocytosis. Preplanned exploratory analyses were progression-free survival, overall survival, sustained haematological improvement, and immunological improvement. Patient enrolment is complete, but follow-up is ongoing. Treatment discontinuation owing to adverse events, unacceptable toxicity, or death were collected as a single combined category. This study is registered with ClinicalTrials.gov, number NCT01744691. FINDINGS: Between Jan 29, 2013, and June 19, 2013, 145 patients were enrolled. The all-treated population consisted of 144 patients with del17p chronic lymphocytic leukaemia or small lymphocytic lymphoma who received at least one dose of study drug, with a median age of 64 years (IQR 57-72) and a median of two previous treatments (IQR 1-3). At the prespecified primary analysis after a median follow-up of 11·5 months (IQR 11·1-13·8), 92 (64%, 95% CI 56-71) of 144 patients had an overall response according to independent review committee assessment; 119 patients (83%, 95% CI 76-88) had an overall response according to investigator assessment. In an extended analysis with median follow-up of 27·6 months (IQR 14·6-27·7), the investigator-assessed overall response was reported in 120 patients (83%, 95% CI 76-89). 24-month progression-free survival was 63% (95% CI 54-70) and 24-month overall survival was 75% (67-81). Sustained haematological improvement was noted in 72 (79%) of 91 patients with any baseline cytopenia. No clinically relevant changes were noted from baseline to 6 months or 24 months in IgA (median 0·4 g/L at baseline, 0·6 g/L at 6 months, and 0·7 g/L at 24 months), IgG (5·0 g/L, 5·3 g/L, and 4·9 g/L), or IgM (0·3 g/L at each timepoint) concentrations. Common reasons for treatment discontinuation were progressive disease in 34 (24%) patients and adverse events, unacceptable toxicity, or death in 24 (17%) patients. Major bleeding occurred in 13 (9%) patients (11 [8%] grade 3-4). Grade 3 or worse infections occurred in 43 (30%) patients, including pneumonia in 19 (13%) patients. In the extended analysis, 38 patients died, 18 as a result of adverse events (four pneumonia, three chronic lymphocytic leukaemia, two Richter's syndrome, two sepsis, and one each of acute myocardial infarction, septic shock, encephalopathy, general deterioration in physical health, abnormal hepatic function, myocardial infarction, and renal infarction). INTERPRETATION: A high proportion of patients had an overall response to ibrutinib and the risk:benefit profile was favourable, providing further evidence for use of ibrutinib in the most difficult subset of patients with chronic lymphocytic leukaemia or small lymphocytic lymphoma. Ibrutinib represents a clinical advance in the treatment of patients with del17p chronic lymphocytic leukaemia and has been incorporated into treatment algorithms as a primary treatment for these patients. FUNDING: Pharmacyclics LLC, an AbbVie Company.

Targeting BTK with ibrutinib in relapsed chronic lymphocytic leukemia.

BACKGROUND: The treatment of relapsed chronic lymphocytic leukemia (CLL) has resulted in few durable remissions. Bruton's tyrosine kinase (BTK), an essential component of B-cell-receptor signaling, mediates interactions with the tumor microenvironment and promotes the survival and proliferation of CLL cells. METHODS: We conducted a phase 1b-2 multicenter study to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of ibrutinib (PCI-32765), a first-in-class, oral covalent inhibitor of BTK designed for treatment of B-cell cancers, in patients with relapsed or refractory CLL or small lymphocytic lymphoma. A total of 85 patients, the majority of whom were considered to have high-risk disease, received ibrutinib orally once daily; 51 received 420 mg, and 34 received 840 mg. RESULTS: Toxic effects were predominantly grade 1 or 2 and included transient diarrhea, fatigue, and upper respiratory tract infection; thus, patients could receive extended treatment with minimal hematologic toxic effects. The overall response rate was the same in the group that received 420 mg and the group that received 840 mg (71%), and an additional 20% and 15% of patients in the respective groups had a partial response with lymphocytosis. The response was independent of clinical and genomic risk factors present before treatment, including advanced-stage disease, the number of previous therapies, and the 17p13.1 deletion. At 26 months, the estimated progression-free survival rate was 75% and the rate of overall survival was 83%. CONCLUSIONS: Ibrutinib was associated with a high frequency of durable remissions in patients with relapsed or refractory CLL and small lymphocytic lymphoma, including patients with high-risk genetic lesions. (Funded by Pharmacyclics and others; ClinicalTrials.gov number, NCT01105247.).

Prolonged lymphocytosis during ibrutinib therapy is associated with distinct molecular characteristics and does not indicate a suboptimal response to therapy.

The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has outstanding activity in patients with chronic lymphocytic leukemia. Most patients experience lymphocytosis, representing lymphocyte egress from nodal compartments. This resolves within 8 months in the majority of patients, but a subgroup has lymphocytosis lasting >12 months. Here we report a detailed characterization of patients with persistent lymphocytosis during ibrutinib therapy. Signaling evaluation showed that while BTK is inhibited, downstream mediators of B-cell receptor (BCR) signaling are activated in persistent lymphocytes. These cells cannot be stimulated through the BCR and do not show evidence of target gene activation. Flow cytometry for κ and λ expression, IGHV sequencing, Zap-70 methylation, and targeted gene sequencing in these patients are identical at baseline and later time points, suggesting that persistent lymphocytes do not represent clonal evolution. In vitro treatment with targeted kinase inhibitors shows that they are not addicted to a single survival pathway. Finally, progression-free survival is not inferior for patients with prolonged lymphocytosis vs those with traditional responses. Thus, prolonged lymphocytosis is common following ibrutinib treatment, likely represents the persistence of a quiescent clone, and does not predict a subgroup of patients likely to relapse early.

Modeling absolute lymphocyte counts after treatment of chronic lymphocytic leukemia with ibrutinib.

The objective in this study was to characterize the pattern of the treatment-related lymphocytosis curve in chronic lymphocytic leukemia (CLL) patients treated with ibrutinib, and assess the relationship between the baseline factors and absolute lymphocyte counts (ALC). The PCYC-1102-CA study was a five-arm phase Ib/II open-label, nonrandomized, multicenter study in CLL/SLL. The arms and accruals were 420 and 840 mg/day treatment-naive elderly CLL/SLL (N = 27 and N = 4, respectively), 420 and 840 mg/day relapsed/refractory CLL/SLL (N = 27 and N = 34, respectively), and 420 mg/day high-risk CLL/SLL (N = 24). The results were generated through statistical modeling using data from a clinical trial (PCYC-1102) in five cohorts of treatment-naïve or relapsed/refractory CLL patients treated at 420 and 840 mg daily of ibrutinib. In cases in which the initial increase in ALC doubles by day 28, it takes patients longer to reach their maximum ALC when compared with those with a lower rate of increase. Our models show that all of the cohorts exhibited the same pattern of treatment-related lymphocytosis from ibrutinib, and there are no significant differences between cohorts, including no detectable dose effect. The ALC of the majority of patients return to baseline ALC values by the end of cycle 5.