The combination of ibrutinib and rituximab demonstrates activity in first-line follicular lymphoma.

This phase 2 study evaluated the activity and safety of ibrutinib, a Bruton's tyrosine kinase inhibitor, plus rituximab in adults with previously untreated follicular lymphoma. Patients received once-daily ibrutinib 560 mg continuously plus once-weekly rituximab 375 mg/m2 for 4 weeks beginning Week 1 (Arm 1, n = 60) or Week 9 (following an 8-week ibrutinib lead-in) to explore biomarkers (Arm 2, n = 20). The primary endpoint was the best overall response rate (ORR). The median age was 58 years; most had an Eastern Cooperative Oncology Group Performance Status of 0 (74%) and Stage III/IV disease (84%). At a median study follow-up of 34 months in Arm 1 and 29 months in Arm 2, ORRs were 85% [95% confidence interval (CI) 73-93] and 75% (95% CI 51-91), respectively, with complete responses in 40% and 50%. The median duration of response was not reached in either arm; 30-month progression-free and overall survival rates were 67% and 97% (Arm 1) and 65% and 100% (Arm 2). The most common adverse events were fatigue, diarrhoea and nausea. Higher grade (Grade 3/4) haematological, haemorrhagic and cardiac events occurred infrequently. Ibrutinib plus rituximab was active and tolerable in first-line follicular lymphoma.

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.

Absence of BTK, BCL2, and PLCG2 Mutations in Chronic Lymphocytic Leukemia Relapsing after First-Line Treatment with Fixed-Duration Ibrutinib plus Venetoclax.

PURPOSE: Mutations in BTK, PLCG2, and BCL2 have been reported in patients with progressive disease (PD) on continuous single-agent BTK or BCL2 inhibitor treatment. We tested for these mutations in samples from patients with PD after completion of first-line treatment with fixed-duration ibrutinib plus venetoclax for chronic lymphocytic leukemia (CLL) in the phase II CAPTIVATE study. PATIENTS AND METHODS: A total of 191 patients completed fixed-duration ibrutinib plus venetoclax (three cycles of ibrutinib then 12-13 cycles of ibrutinib plus venetoclax). Genomic risk features [del(11q), del(13q), del(17p), trisomy 12, complex karyotype, unmutated IGHV, TP53 mutated] and mutations in genes recurrently mutated in CLL (ATM, BIRC3, BRAF, CHD2, EZH2, FBXW7, MYD88, NOTCH1, POT1, RPS15, SF3B1, XPO1) were assessed at baseline in patients with and without PD at data cutoff; gene variants and resistance-associated mutations in BTK, PLCG2, or BCL2 were evaluated at PD. RESULTS: Of 191 patients completing fixed-duration ibrutinib plus venetoclax, with median follow-up of 38.9 months, 29 (15%) developed PD. No baseline risk feature or gene mutation was significantly associated with development of PD. No previously reported resistance-associated mutations in BTK, PLCG2, or BCL2 were detected at PD in 25 patients with available samples. Of the 29 patients with PD, 19 have required retreatment (single-agent ibrutinib, n = 16, or ibrutinib plus venetoclax, n = 3); 17 achieved partial response or better, 1 achieved stable disease, and 1 is pending response assessment. CONCLUSIONS: First-line fixed-duration combination treatment with ibrutinib plus venetoclax may mitigate development of resistance mechanisms associated with continuous single-agent targeted therapies, allowing for effective retreatment. See related commentary by Al-Sawaf and Davids, p. 471.

The iR2 regimen (ibrutinib plus lenalidomide and rituximab) for relapsed/refractory DLBCL: A multicentre, non-randomised, open-label phase 2 study.

Background: This phase 1b/2 PCYC-1123-CA study evaluated efficacy and safety of the combination of ibrutinib, lenalidomide, and rituximab (iR2 regimen) in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) ineligible for stem cell transplantation. Methods: In phase 2, patients with relapsed/refractory non-germinal centre B-cell-like DLBCL received oral ibrutinib 560 mg once daily and oral lenalidomide 20 mg or 25 mg once daily on Days 1-21 of each 28-day cycle until disease progression or unacceptable toxicity and intravenous rituximab 375 mg/m2 on Day 1 of Cycles 1-6. The primary endpoint was overall response rate (ORR) in the response-evaluable population (received any study treatment and had ≥1 post-baseline disease assessment). The study was done at 24 academic and community hospitals in Belgium, Germany, United Kingdom, and USA. This study was registered with ClinicalTrials.gov, NCT02077166. Findings: Between March 13, 2014 and October 2, 2018, 89 patients were enrolled with a median time on study of 35.0 months. Best ORR in the response-evaluable population (n = 85) was 49% (95% confidence interval [CI], 38-61) across dose cohorts and 53% (95% CI, 39-67) and 44% (95% CI, 26-62) in the 20 mg and 25 mg lenalidomide cohorts, respectively, with complete responses in 24/85 (28%), 17/53 (32%), and 7/32 (22%) patients, respectively. Grade 3/4 adverse events (AEs) occurred in 81/89 patients (91%), most frequently neutropenia (36/89; 40%), maculopapular rash (16/89; 18%), anaemia (12/89; 13%), and diarrhoea (9/89; 10%). Serious adverse events occurred in 57/89 patients (64%). Fatal AEs occurred in 12/89 patients (13%); causes of death were worsening of DLBCL (n = 7), pneumonia (n = 3), sepsis (n = 1), and cardiac arrest (n = 1). Interpretation: The most frequent AEs (diarrhoea, neutropenia, fatigue, cough, anaemia, peripheral oedema, and maculopapular rash) were consistent with known safety profiles of the individual drugs. The iR2 regimen demonstrated antitumour activity with durable responses in patients with relapsed/refractory DLBCL. Funding: Pharmacyclics LLC, an AbbVie Company.

Concurrent ibrutinib plus venetoclax in relapsed/refractory mantle cell lymphoma: the safety run-in of the phase 3 SYMPATICO study.

Ibrutinib plus venetoclax, given with an ibrutinib lead-in, has shown encouraging clinical activity in early phase studies in mantle cell lymphoma (MCL). The ongoing phase 3 SYMPATICO study evaluates the safety and efficacy of concurrently administered, once-daily, all-oral ibrutinib plus venetoclax in patients with relapsed/refractory MCL. A safety run-in (SRI) cohort was conducted to inform whether an ibrutinib lead-in should be implemented for the randomized portion. Patients received concurrent ibrutinib 560 mg continuously plus venetoclax in a 5-week ramp-up to venetoclax 400 mg for up to 2 years. The primary endpoint was occurrence of tumor lysis syndrome (TLS) and dose-limiting toxicities (DLTs). The SRI cohort enrolled 21 patients; six and 15 were in low- or increased-risk categories for TLS, respectively. During the 5-week venetoclax ramp-up, three patients had DLTs, and one patient at increased risk for TLS had a laboratory TLS; no additional TLS events occurred during follow-up. With a median follow-up of 31 months, the overall response rate was 81% (17/21); 62% (13/21) of patients had a complete response. SRI data informed that the randomized portion should proceed with concurrent ibrutinib plus venetoclax, with no ibrutinib lead-in. Ibrutinib plus venetoclax demonstrated promising efficacy; no new safety signals were observed.Trial registration: ClinicalTrials.gov, NCT03112174. Registered 13 April 2017, https://clinicaltrials.gov/ct2/show/NCT03112174 .

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.

Improvement in Parameters of Hematologic and Immunologic Function and Patient Well-being in the Phase III RESONATE Study of Ibrutinib Versus Ofatumumab in Patients With Previously Treated Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma.

BACKGROUND: Ibrutinib compared with ofatumumab significantly improves progression-free and overall survival in patients with previously treated chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). PATIENTS AND METHODS: Measures of well-being were assessed in RESONATE, where previously treated patients with CLL/SLL were randomized to receive ibrutinib 420 mg/day (n = 195) or ofatumumab (n = 196) for up to 24 weeks. Endpoints included hematologic function, Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), disease-related symptoms, European Organization for Research and Treatment of Cancer Quality of Life Questionnaires Core 30 (EORTC QLQ-C30), and medical resource utilization. RESULTS: With up to 24 months' follow-up (median, 16.4 months), 79% of cytopenic patients showed sustained hematologic improvement (82% with improved platelet count, 69% with improved hemoglobin) on ibrutinib versus 43% on ofatumumab (P < .0001). Higher rates of clinically meaningful improvement were demonstrated with ibrutinib versus ofatumumab for FACIT-F and EORTC global health. Greater improvement was observed in disease-related weight loss, fatigue, night sweats, and abdominal discomfort with ibrutinib versus ofatumumab. Hospitalizations in the first 30 days occurred less frequently with ibrutinib than ofatumumab (0.087 vs. 0.184 events/patient; P = .0198). New-onset diarrhea was infrequent with ibrutinib after the first 6 months (47% at ≤6 months vs. 5% at 12-18 months). With ibrutinib, grade ≥ 3 hypertension occurred in 6%, grade ≥ 3 atrial fibrillation in 4%, major hemorrhage in 2%, and tumor lysis syndrome in 1% of patients. CONCLUSION: Ibrutinib led to significant improvements in hematologic function and disease symptomatology versus ofatumumab, and can restore quality of life while prolonging survival in relapsed/refractory CLL/SLL.

Combination of Ibrutinib and ABT-199 in Diffuse Large B-Cell Lymphoma and Follicular Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma are the most prevalent B-lymphocyte neoplasms in which abnormal activation of the Bruton tyrosine kinase (BTK)-mediated B-cell receptor signaling pathway contributes to pathogenesis. Ibrutinib is an oral covalent BTK inhibitor that has shown some efficacy in both indications. To improve ibrutinib efficacy through combination therapy, we first investigated differential gene expression in parental and ibrutinib-resistant cell lines to better understand the mechanisms of resistance. Ibrutinib-resistant TMD8 cells had higher BCL2 gene expression and increased sensitivity to ABT-199, a BCL-2 inhibitor. Consistently, clinical samples from ABC-DLBCL patients who experienced poorer response to ibrutinib had higher BCL2 gene expression. We further demonstrated synergistic growth suppression by ibrutinib and ABT-199 in multiple ABC-DLBCL, GCB-DLBCL, and follicular lymphoma cell lines. The combination of both drugs also reduced colony formation, increased apoptosis, and inhibited tumor growth in a TMD8 xenograft model. A synergistic combination effect was also found in ibrutinib-resistant cells generated by either genetic mutation or drug treatment. Together, these findings suggest a potential clinical benefit from ibrutinib and ABT-199 combination therapy. Mol Cancer Ther; 16(7); 1246-56. ©2017 AACR.

The role of PIM1 in the ibrutinib-resistant ABC subtype of diffuse large B-cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is a heterogeneous lymphoma and the most common subtype of non-Hodgkin lymphoma, accounting for roughly 30% of newly diagnosed cases in the United States. DLBCL can be separated into the activated B cell-like (ABC) and germinal center B cell-like (GCB) subtypes, with distinct gene expression profiles, oncogenic aberrations, and clinical outcomes. ABC-DLBCL is characterized by chronically active B-cell receptor (BCR) signaling that can be modulated by Bruton's tyrosine kinase (BTK) activity. Thus, BTK serves as an attractive therapeutic target in this type of B-cell malignancy. Ibrutinib, a first-in-class, orally available covalent BTK inhibitor, has demonstrated clinical activity in several B-cell leukemias and lymphomas. A phase 1/2 clinical trial of single-agent ibrutinib in relapsed and refractory DLBCL patients revealed an overall response rate of 37% in ABC-DLBCL patients. However, responses to kinase-directed therapies are often limited by emerging resistance mechanisms that bypass the therapeutic target. Here we report the discovery of point mutations within the kinase PIM1 that reduce sensitivity to ibrutinib in ABC-DLBCL. These mutations stabilize PIM1 and affect upstream regulators and downstream targets of NF-κB signaling. The introduction of mutant PIM1 into an ABC-DLBCL cell line, TMD8, increased colony formation and decreased sensitivity to ibrutinib. In addition, ibrutinib-resistant cell lines generated by prolonged ibrutinib exposure in vitro upregulated PIM1 expression, consistent with a role for PIM1 in antagonizing ibrutinib activity. The combination of a pan-PIM inhibitor with ibrutinib synergistically inhibited proliferation in vitro and tumor growth in vivo. Together, these data provide a rationale for combining BTK and PIM1 inhibition in the treatment of ABC-DLBCL.

Engraftment of sorted/expanded human central nervous system stem cells from fetal brain.

Direct isolation of human central nervous system stem cells (CNS-SC) based on cell surface markers yields a highly purified stem cell population that can extensively expand in vitro and exhibit multilineage differentiation potential both in vitro and in vivo. The CNS-SC were isolated from fetal brain tissue using the cell surface markers CD133(+), CD34(-), CD45(-), and CD24(-/lo) (CD133(+) cells). Fluorescence-activated cell sorted (FACS) CD133(+) cells continue to expand exponentially as neurospheres while retaining multipotential differentiation capacity for >10 passages. CD133(-), CD34(-), and CD45(-) sorted cells (approximately 95% of total fetal brain tissue) fail to initiate neurospheres. Neurosphere cells transplanted into neonatal immunodeficient NOD-SCID mice proliferated, migrated, and differentiated in a site-specific manner. However, it has been difficult to evaluate human cell engraftment, because many of the available monoclonal antibodies against neural cells (beta-tubulin III and glial fibrillary acidic protein) are not species specific. To trace the progeny of human cells after transplantation, CD133(+)-derived neurosphere cells were transduced with lentiviral vectors containing enhanced green fluorescent protein (eGFP) expressed downstream of the phosphoglycerate kinase promoter. After transduction, GFP(+) cells were enriched by FACS, expanded, and transplanted into the lateral ventricular space of neonatal immunodeficient NOD-SCID brain. The progeny of transplanted cells were detected by either GFP fluorescence or antibody against GFP. GFP(+) cells were present in the subventricular zone-rostral migrating stream, olfactory bulb, and hippocampus as well as nonneurogenic sites, such as cerebellum, cerebral cortex, and striatum. Antibody against GFP revealed that some of the cells displayed differentiating dendrites and processes with neurons or glia cells. Thus, marking human CNS-SC with reporter genes introduced by lentiviral vectors is a useful tool with which to characterize migration and differentiation of human cells in this mouse transplantation model.