Shuo Ma

Idelalisib and Rituximab in Relapsed Chronic Lymphocytic Leukemia

BACKGROUND Patients with relapsed chronic lymphocytic leukemia (CLL) who have clinically significant coexisting medical conditions are less able to undergo standard chemotherapy. Effective therapies with acceptable side-effect profiles are needed for this patient population. METHODS In this multicenter, randomized, double-blind, placebo-controlled, phase 3 study, we assessed the efficacy and safety of idelalisib, an oral inhibitor of the delta isoform of phosphatidylinositol 3-kinase, in combination with rituximab versus rituximab plus placebo. We randomly assigned 220 patients with decreased renal function, previous therapy-induced myelosuppression, or major coexisting illnesses to receive rituximab and either idelalisib (at a dose of 150 mg) or placebo twice daily. The primary end point was progression-free survival. At the first prespecified interim analysis, the study was stopped early on the recommendation of the data and safety monitoring board owing to overwhelming efficacy. RESULTS The median progression-free survival was 5.5 months in the placebo group and was not reached in the idelalisib group (hazard ratio for progression or death in the idelalisib group, 0.15; P<0.001). Patients receiving idelalisib versus those receiving placebo had improved rates of overall response (81% vs. 13%; odds ratio, 29.92; P<0.001) and overall survival at 12 months (92% vs. 80%; hazard ratio for death, 0.28; P=0.02). Serious adverse events occurred in 40% of the patients receiving idelalisib and rituximab and in 35% of those receiving placebo and rituximab. CONCLUSIONS The combination of idelalisib and rituximab, as compared with placebo and rituximab, significantly improved progression-free survival, response rate, and overall survival among patients with relapsed CLL who were less able to undergo chemotherapy. (Funded by Gilead; ClinicalTrials.gov number, NCT01539512.).

Regulation of Leukocyte Transmigration: Cell Surface Interactions and Signaling Events

A fundamental event in the inflammatory response is recruitment of blood leukocytes to a site of injury or infection, often resulting in tissue dysfunction and damage. The steps in this recruitment process are leukocyte adhesion to the endothelial lining of the vessel wall, diapedesis, or

Venetoclax plus rituximab in relapsed or refractory chronic lymphocytic leukaemia: a phase 1b study.

BACKGROUND Selective BCL2 inhibition with venetoclax has substantial activity in patients with relapsed or refractory chronic lymphocytic leukaemia. Combination therapy with rituximab enhanced activity in preclinical models. The aim of this study was to assess the safety, pharmacokinetics, and activity of venetoclax in combination with rituximab. METHODS Adult patients with relapsed or refractory chronic lymphocytic leukaemia (according to the 2008 Modified International Workshop on CLL guidelines) or small lymphocytic lymphoma were eligible for this phase 1b, dose-escalation trial. The primary outcomes were to assess the safety profile, to determine the maximum tolerated dose, and to establish the recommended phase 2 dose of venetoclax when given in combination with rituximab. Secondary outcomes were to assess the pharmacokinetic profile and analyse efficacy, including overall response, duration of response, and time to tumour progression. Minimal residual disease was a protocol-specified exploratory objective. Central review of the endpoints was not done. Venetoclax was dosed daily using a stepwise escalation to target doses (200-600 mg) and then monthly rituximab commenced (375 mg/m2 in month 1 and 500 mg/m2 in months 2-6). Adverse events were graded according to the National Cancer Institute Common Terminology Criteria for adverse events version 4.0. Protocol-guided drug cessation was allowed for patients who achieved complete response (including complete response with incomplete marrow recovery) or negative bone marrow minimal residual disease. Analyses were done per protocol for all patients who commenced drug and included all patients who received at least one dose of venetoclax. Data were pooled across dose cohorts. Patients are still receiving therapy and follow-up is ongoing. The trial is registered at ClinicalTrials.gov, number NCT01682616. FINDINGS Between Aug 6, 2012, and May 28, 2014, we enrolled 49 patients. Common grade 1-2 toxicities included upper respiratory tract infections (in 28 [57%] of 49 patients), diarrhoea (27 [55%]), and nausea (25 [51%]). Grade 3-4 adverse events occurred in 37 (76%) of 49 patients; most common were neutropenia (26 [53%]), thrombocytopenia (eight [16%]), anaemia (seven [14%]), febrile neutropenia (six [12%]), and leucopenia (six [12%]). The most common serious adverse events were pyrexia (six [12%]), febrile neutropenia (five [10%]), lower respiratory tract infection, and pneumonia (each three [6%]). Clinical tumour lysis syndrome occurred in two patients (resulting in one death) who initiated venetoclax at 50 mg. After enhancing tumour lysis syndrome prophylaxis measures and commencing venetoclax at 20 mg, clinical tumour lysis syndrome did not occur. The maximum tolerated dose was not identified; the recommended phase 2 dose of venetoclax in combination with rituximab was 400 mg. Overall, 42 (86%) of 49 patients achieved a response, including a complete response in 25 (51%) of 49 patients. 2 year estimates for progression-free survival and ongoing response were 82% (95% CI 66-91) and 89% (95% CI 72-96), respectively. Negative marrow minimal residual disease was attained in 20 (80%) of 25 complete responders and 28 (57%) of 49 patients overall. 13 responders ceased all therapy; among these all 11 minimal residual disease-negative responders remain progression-free off therapy. Two with minimal residual disease-positive complete response progressed after 24 months off therapy and re-attained response after re-initiation of venetoclax. INTERPRETATION A substantial proportion of patients achieved an overall response with the combination of venetoclax and rituximab including 25 (51%) of 49 patients who achieved a complete response and 28 (57%) of 49 patients who achieved negative marrow minimal residual disease with acceptable safety. The depth and durability of responses observed with the combination offers an attractive potential treatment option for patients with relapsed or refractory chronic lymphocytic leukaemia and could allow some patients to maintain response after discontinuing therapy, a strategy that warrants further investigation in randomised studies. FUNDING AbbVie Inc and Genentech Inc.

The role of endothelial cell lateral junctions during leukocyte trafficking

Summary: An essential function of the inflammatory response is selective targeting of appropriate leukocyte types to a site of infection or injury. The past decade has witnessed an explosion in the level of detail concerning the identification and deciphering of the molecular mechanisms that capture leukocytes from flowing blood and promote leukocyte arrest on the vessel wall. In contrast, less information is known about the migration of adherent blood leukocytes through endothelial cell‐to‐cell borders (transendothelial migration, TEM) and into the underlying tissues. This article reviews the endothelial‐dependent mechanisms that coordinate TEM in peripheral vasculature and highlights the role of certain lateral junctional proteins and protein complexes.

Nuclear overexpression of lymphoid-enhancer-binding factor 1 identifies chronic lymphocytic leukemia/small lymphocytic lymphoma in small B-cell lymphomas

Lymphoid-enhancer-binding factor 1 (LEF1), coupling with β-catenin, functions as a key nuclear mediator of WNT/β-catenin signaling, which regulates cell proliferation and survival. LEF1 has an important role in lymphopoiesis, and is normally expressed in T and pro-B cells but not mature B cells. However, gene expression profiling demonstrates overexpression of LEF1 in chronic lymphocytic leukemia, and knockdown of LEF1 decreases the survival of the leukemic cells. So far, the data on LEF1 expression in B-cell lymphomas are limited. This study represents the first attempt to assess LEF1 by immunohistochemistry in a large series (290 cases) of B-cell lymphomas. Strong nuclear staining of LEF1 was observed in virtually all neoplastic cells in 92 of 92 (100%) chronic lymphocytic leukemia/small lymphocytic lymphomas including two CD5− cases, with strongest staining in cells with Richters transformation. LEF1 also highlighted the morphologically inconspicuous small lymphocytic lymphoma component in three composite lymphomas. All 53 mantle cell lymphomas, 31 low-grade follicular lymphomas and 31 marginal zone lymphomas, including 3 CD5+ cases, were negative. In 12 grade 3 follicular lymphomas, LEF1 was positive in a small subset (5–15%) of cells. Diffuse large B-cell lymphoma, however, demonstrated significant variability in LEF1 expression with overall positivity in 27 of 71 (38%) cases. Our results demonstrate that nuclear overexpression of LEF1 is highly associated with chronic lymphocytic leukemia/small lymphocytic lymphoma, and may serve as a convenient marker for differential diagnosis of small B-cell lymphomas. The expression of β-catenin, the coactivator of LEF1 in WNT signaling, was examined in 50 chronic lymphocytic leukemia/small lymphocytic lymphomas, of which 44 (88%) showed negative nuclear staining. The findings of universal nuclear overexpression of LEF1 but lack of nuclear β-catenin in the majority of chronic lymphocytic leukemia/small lymphocytic lymphoma suggest that the pro-survival function of LEF1 in this disease may be independent of WNT/β-catenin signaling.

Ibrutinib for patients with rituximab-refractory Waldenström's macroglobulinaemia (iNNOVATE): an open-label substudy of an international, multicentre, phase 3 trial

BACKGROUND In the era of widespread rituximab use for Waldenströms macroglobulinaemia, new treatment options for patients with rituximab-refractory disease are an important clinical need. Ibrutinib has induced durable responses in previously treated patients with Waldenströms macroglobulinaemia. We assessed the efficacy and safety of ibrutinib in a population with rituximab-refractory disease. METHODS This multicentre, open-label substudy was done at 19 sites in seven countries in adults aged 18 years and older with confirmed Waldenströms macroglobulinaemia, refractory to rituximab and requiring treatment. Disease refractory to the last rituximab-containing therapy was defined as either relapse less than 12 months since last dose of rituximab or failure to achieve at least a minor response. Key exclusion criteria included: CNS involvement, a stroke or intracranial haemorrhage less than 12 months before enrolment, clinically significant cardiovascular disease, hepatitis B or hepatitis C viral infection, and a known bleeding disorder. Patients received oral ibrutinib 420 mg once daily until progression or unacceptable toxicity. The substudy was not prospectively powered for statistical comparisons, and as such, all the analyses are descriptive in nature. This study objectives were the proportion of patients with an overall response, progression-free survival, overall survival, haematological improvement measured by haemoglobin, time to next treatment, and patient-reported outcomes according to the Functional Assessment of Cancer Therapy-Anemia (FACT-An) and the Euro Qol 5 Dimension Questionnaire (EQ-5D-5L). All analyses were per protocol. The study is registered at ClinicalTrials.gov, number NCT02165397, and follow-up is ongoing but enrolment is complete. FINDINGS Between Aug 18, 2014, and Feb 18, 2015, 31 patients were enrolled. Median age was 67 years (IQR 58-74); 13 (42%) of 31 patients had high-risk disease per the International Prognostic Scoring System Waldenström Macroglobulinaemia, median number of previous therapies was four (IQR 2-6), and all were rituximab-refractory. At a median follow-up of 18·1 months (IQR 17·5-18·9), the proportion of patients with an overall response was 28 [90%] of 31 (22 [71%] of patients had a major response), the estimated 18 month progression-free survival rate was 86% (95% CI 66-94), and the estimated 18 month overall survival rate was 97% (95% CI 79-100). Baseline median haemoglobin of 10·3 g/dL (IQR 9·3-11·7) increased to 11·4 g/dL (10·9-12·4) after 4 weeks of ibrutinib treatment and reached 12·7 g/dL (11·8-13·4) at week 49. A clinically meaningful improvement from baseline in FACT-An score, anaemia subscale score, and the EQ-5D-5L were reported at all post-baseline visits. Time to next treatment will be presented at a later date. Common grade 3 or worse adverse events included neutropenia in four patients (13%), hypertension in three patients (10%), and anaemia, thrombocytopenia, and diarrhoea in two patients each (6%). Serious adverse events occurred in ten patients (32%) and were most often infections. Five (16%) patients discontinued ibrutinib: three due to progression and two due to adverse events, while the remaining 26 [84%] of patients are continuing ibrutinib at the time of this report. INTERPRETATION The sustained responses and median progression-free survival time, combined with a manageable toxicity profile observed with single-agent ibrutinib indicate that this chemotherapy-free approach is a potential new treatment choice for patients who had heavily pretreated, rituximab-refractory Waldenströms macroglobulinaemia. FUNDING Pharmacyclics LLC, an AbbVie Company.

Targeting Bruton tyrosine kinase with ibrutinib in relapsed/refractory marginal zone lymphoma

Marginal zone lymphoma (MZL) is a heterogeneous B-cell malignancy for which no standard treatment exists. MZL is frequently linked to chronic infection, which may induce B-cell receptor (BCR) signaling, resulting in aberrant B-cell survival and proliferation. We conducted a multicenter, open-label, phase 2 study to evaluate the efficacy and safety of ibrutinib in previously treated MZL. Patients with histologically confirmed MZL of all subtypes who received ≥1 prior therapy with an anti-CD20 antibody-containing regimen were treated with 560 mg ibrutinib orally once daily until progression or unacceptable toxicity. The primary end point was independent review committee-assessed overall response rate (ORR) by 2007 International Working Group criteria. Among 63 enrolled patients, median age was 66 years (range, 30-92). Median number of prior systemic therapies was 2 (range, 1-9), and 63% received ≥1 prior chemoimmunotherapy. In 60 evaluable patients, ORR was 48% (95% confidence interval [CI], 35-62). With median follow-up of 19.4 months, median duration of response was not reached (95% CI, 16.7 to not estimable), and median progression-free survival was 14.2 months (95% CI, 8.3 to not estimable). Grade ≥3 adverse events (AEs; >5%) included anemia, pneumonia, and fatigue. Serious AEs of any grade occurred in 44%, with grade 3-4 pneumonia being the most common (8%). Rates of discontinuation and dose reductions due to AEs were 17% and 10%, respectively. Single-agent ibrutinib induced durable responses with a favorable benefit-risk profile in patients with previously treated MZL, confirming the role of BCR signaling in this malignancy. As the only approved therapy, ibrutinib provides a treatment option without chemotherapy for MZL. This study is registered at www.clinicaltrials.gov as #NCT01980628.

Phase I study of single-agent CC-292, a highly selective Bruton's tyrosine kinase inhibitor, in relapsed/refractory chronic lymphocytic leukemia.

B-cell receptor (BCR) signaling plays a key role in the pathogenesis of B-cell malignancies, mediating the survival and proliferation of malignant B cells.[1][1],[2][2] Clinical studies have shown that Bruton’s tyrosine kinase (BTK) inhibitors are well tolerated, with promising clinical activity.

Molecular motors and membrane traffic in Dictyostelium.

Phagocytosis and membrane traffic in general are largely dependent on the cytoskeleton and their associated molecular motors. The myosin family of motors, especially the unconventional myosins, interact with the actin cortex to facilitate the internalization of external materials during the early steps of phagocytosis. Members of the kinesin and dynein motor families, which mediate transport along microtubules (MTs), facilitate the intracellular processing of the internalized materials and the movement of membrane. Recent studies indicate that some unconventional myosins are also involved in membrane transport, and that the MT- and actin-dependent transport systems might interact with each other. Studies in Dictyostelium have led to the discovery of many motors involved in critical steps of phagocytosis and membrane transport. With the ease of genetic and biochemical approaches, the established functional analysis to test phagocytosis and vesicle transport, and the effort of the Dictyostelium cDNA and Genome Projects, Dictyostelium will continue to be a superb model system to study phagocytosis in particular and cytoskeleton and motors in general.

Signal transduction inhibitors in chronic lymphocytic leukemia.

Purpose of review Chronic lymphocytic leukemia (CLL) therapy has evolved over the past few decades as modern chemo-immunotherapy significantly improved the response and survival of CLL patients. However, treatment toxicity of the intensive chemo-immunotherapy often limits its use in the mostly elderly population of patients. Further, the disease eventually relapses and additional therapy options are required. Of particular interest are molecular targeted therapies that interfere with critical signal transduction pathways controlling cell growth and survival. This review will provide an update on the most recent preclinical and clinical development of signal transduction targeted therapy in CLL. Recent findings Small molecular kinase inhibitors have been developed to target the proximal B-cell receptor signaling pathway (e.g. spleen tyrosine kinase inhibitors and Brutons tyrosine kinase inhibitors) or the downstream phosphatidylinositol-3 kinase/Akt/mammalian target of rapamycin pathway. These agents showed unique in-vitro activities by inducing apoptosis and blocking interaction of CLL cells and the protective microenvironment. They have also shown promising clinical activity in early-phase clinical studies and appear to alter lymphocyte trafficking. Inhibitors of the B-cell CLL/lymphoma 2 (BCL-2) family of antiapoptotic proteins and Cdk inhibitors are in active clinical development. Strategies modulating the CLL interaction with the microenvironment niche are emerging. Further understanding of novel signaling pathways helps to identify additional potential therapeutic targets. Summary Signal transduction inhibitors are promising new strategy for targeted CLL treatment. Identification of novel molecular targets and therapeutic agents will further expand our therapeutic options.