Ibrutinib alone or with dexamethasone for relapsed or relapsed and refractory multiple myeloma: phase 2 trial results.

Novel therapies with unique new targets are needed for patients who are relapsed/refractory to current treatments for multiple myeloma. Ibrutinib is a first-in-class, once-daily, oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in the myeloma stem cell population. This study examined various doses of ibrutinib ± low-dose dexamethasone in patients who received ≥2 prior lines of therapy, including an immunomodulatory agent. Daily ibrutinib ± weekly dexamethasone 40 mg was assessed in 4 cohorts using a Simon 2-stage design. The primary objective was clinical benefit rate (CBR; ≥minimal response); secondary objectives included safety. Patients (n = 92) received a median of 4 prior regimens. Ibrutinib + dexamethasone produced the highest CBR (28%) in Cohort 4 (840 mg + dexamethasone; n = 43), with median duration of 9·2 months (range, 3·0-14·7). Progression-free survival was 4·6 months (range, 0·4-17·3). Grade 3-4 haematological adverse events included anaemia (16%), thrombocytopenia (11%), and neutropenia (2%); grade 3-4 non-haematological adverse events included pneumonia (7%), syncope (3%) and urinary tract infection (3%). Ibrutinib + dexamethasone produced notable responses in this heavily pre-treated population. The encouraging efficacy, coupled with the favourable safety and tolerability profile of ibrutinib, supports its further evaluation as part of combination treatment.

Immune responses and long-term disease recurrence status after telomerase-based dendritic cell immunotherapy in patients with acute myeloid leukemia.

BACKGROUND: Telomerase activity in leukemic blasts frequently is increased among patients with high-risk acute myeloid leukemia (AML). In the current study, the authors evaluated the feasibility, safety, immunogenicity, and therapeutic potential of human telomerase reverse transcriptase (hTERT)-expressing autologous dendritic cells (hTERT-DCs) in adult patients with AML. METHODS: hTERT-DCs were produced from patient-specific leukapheresis, electroporated with an mRNA-encoding hTERT and a lysosomal-targeting sequence, and cryopreserved. A total of 22 patients with a median age of 58 years (range, 30-75 years) with intermediate-risk or high-risk AML in first or second complete remission (CR) were enrolled. hTERT-DCs were generated for 24 patients (73%). A median of 17 intradermal vaccinations (range, 6-32 intradermal vaccinations) containing 1×107 cells were administered as 6 weekly injections followed by 6 biweekly injections. A total of 21 patients (16 in first CR, 3 in second CR, and 2 with early disease recurrence) received hTERT-DCs. RESULTS: hTERT-DCs were well tolerated with no severe toxicities reported, with the exception of 1 patient who developed idiopathic thrombocytopenic purpura. Of the 19 patients receiving hTERT-DCs in CR, 11 patients (58%) developed hTERT-specific T-cell responses that primarily were targeted toward hTERT peptides with predicted low human leukocyte antigen (HLA)-binding affinities. With a median follow-up of 52 months, 58% of patients in CR (11 of 19 patients) were free of disease recurrence at the time of their last follow-up visit; 57% of the patients who were aged ≥60 years (4 of 7 patients) also were found to be free of disease recurrence at a median follow-up of 54 months. CONCLUSIONS: The generation of hTERT-DCs is feasible and vaccination with hTERT-DCs appears to be safe and may be associated with favorable recurrence-free survival. Cancer 2017;123:3061-72. © 2017 American Cancer Society.

Ibrutinib Inhibits ERBB Receptor Tyrosine Kinases and HER2-Amplified Breast Cancer Cell Growth.

Ibrutinib is a potent, small-molecule Bruton tyrosine kinase (BTK) inhibitor developed for the treatment of B-cell malignancies. Ibrutinib covalently binds to Cys481 in the ATP-binding domain of BTK. This cysteine residue is conserved among 9 other tyrosine kinases, including HER2 and EGFR, which can be targeted. Screening large panels of cell lines demonstrated that ibrutinib was growth inhibitory against some solid tumor cells, including those inhibited by other HER2/EGFR inhibitors. Among sensitive cell lines, breast cancer lines with HER2 overexpression were most potently inhibited by ibrutinib (<100 nmol/L); in addition, the IC50s were lower than that of lapatinib and dacomitinib. Inhibition of cell growth by ibrutinib coincided with downregulation of phosphorylation on HER2 and EGFR and their downstream targets, AKT and ERK. Irreversible inhibition of HER2 and EGFR in breast cancer cells was established after 30-minute incubation above 100 nmol/L or following 2-hour incubation at lower concentrations. Furthermore, ibrutinib inhibited recombinant HER2 and EGFR activity that was resistant to dialysis and rapid dilution, suggesting an irreversible interaction. The dual activity toward TEC family (BTK and ITK) and ERBB family kinases was unique to ibrutinib, as ERBB inhibitors do not inhibit or covalently bind BTK or ITK. Xenograft studies with HER2+ MDA-MB-453 and BT-474 cells in mice in conjunction with determination of pharmacokinetics demonstrated significant exposure-dependent inhibition of growth and key signaling molecules at levels that are clinically achievable. Ibrutinib's unique dual spectrum of activity against both TEC family and ERBB kinases suggests broader applications of ibrutinib in oncology. Mol Cancer Ther; 15(12); 2835-44. ©2016 AACR.

Ibrutinib exerts potent antifibrotic and antitumor activities in mouse models of pancreatic adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense stromal fibroinflammatory reaction that is a major obstacle to effective therapy. The desmoplastic stroma comprises many inflammatory cells, in particular mast cells as key components of the PDAC microenvironment, and such infiltration correlates with poor patient outcome. Indeed, it has been hypothesized that stromal ablation is critical to improve clinical response in patients with PDAC. Ibrutinib is a clinically approved Bruton's tyrosine kinase inhibitor that inhibits mast cells and tumor progression in a mouse model of ß-cell tumorigenesis. Here, we show that ibrutinib is highly effective at limiting the growth of PDAC in both transgenic mouse and patient-derived xenograft models of the disease. In these various experimental settings, ibrutinib effectively diminished fibrosis, extended survival, and improved the response to clinical standard-of-care therapy. Our results offer a preclinical rationale to immediately evaluate the clinical efficacy of ibrutinib in patients with PDAC.

Ibrutinib treatment ameliorates murine chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a life-threatening impediment to allogeneic hematopoietic stem cell transplantation, and current therapies do not completely prevent and/or treat cGVHD. CD4+ T cells and B cells mediate cGVHD; therefore, targeting these populations may inhibit cGVHD pathogenesis. Ibrutinib is an FDA-approved irreversible inhibitor of Bruton's tyrosine kinase (BTK) and IL-2 inducible T cell kinase (ITK) that targets Th2 cells and B cells and produces durable remissions in B cell malignancies with minimal toxicity. Here, we evaluated whether ibrutinib could reverse established cGVHD in 2 complementary murine models, a model interrogating T cell-driven sclerodermatous cGVHD and an alloantibody-driven multiorgan system cGVHD model that induces bronchiolar obliterans (BO). In the T cell-mediated sclerodermatous cGVHD model, ibrutinib treatment delayed progression, improved survival, and ameliorated clinical and pathological manifestations. In the alloantibody-driven cGVHD model, ibrutinib treatment restored pulmonary function and reduced germinal center reactions and tissue immunoglobulin deposition. Animals lacking BTK and ITK did not develop cGVHD, indicating that these molecules are critical to cGVHD development. Furthermore, ibrutinib treatment reduced activation of T and B cells from patients with active cGVHD. Our data demonstrate that B cells and T cells drive cGVHD and suggest that ibrutinib has potential as a therapeutic agent, warranting consideration for cGVHD clinical trials.

Egress of CD19(+)CD5(+) cells into peripheral blood following treatment with the Bruton tyrosine kinase inhibitor ibrutinib in mantle cell lymphoma patients.

Ibrutinib (PCI-32765) is a highly potent oral Bruton tyrosine kinase (BTK) inhibitor in clinical development for treating B-cell lymphoproliferative diseases. Patients with chronic lymphocytic leukemia (CLL) often show marked, transient increases of circulating CLL cells following ibrutinib treatments, as seen with other inhibitors of the B-cell receptor (BCR) pathway. In a phase 1 study of ibrutinib, we noted similar effects in patients with mantle cell lymphoma (MCL). Here, we characterize the patterns and phenotypes of cells mobilized among patients with MCL and further investigate the mechanism of this effect. Peripheral blood CD19(+)CD5(+) cells from MCL patients were found to have significant reduction in the expression of CXCR4, CD38, and Ki67 after 7 days of treatment. In addition, plasma chemokines such as CCL22, CCL4, and CXCL13 were reduced 40% to 60% after treatment. Mechanistically, ibrutinib inhibited BCR- and chemokine-mediated adhesion and chemotaxis of MCL cell lines and dose-dependently inhibited BCR, stromal cell, and CXCL12/CXCL13 stimulations of pBTK, pPLCγ2, pERK, or pAKT. Importantly, ibrutinib inhibited migration of MCL cells beneath stromal cells in coculture. We propose that BTK is essential for the homing of MCL cells into lymphoid tissues, and its inhibition results in an egress of malignant cells into peripheral blood. This trial was registered at www.clinicaltrials.gov as #NCT00114738.

Bruton tyrosine kinase inhibition is a novel therapeutic strategy targeting tumor in the bone marrow microenvironment in multiple myeloma.

Bruton tyrosine kinase (Btk) has a well-defined role in B-cell development, whereas its expression in osteoclasts (OCs) further suggests a role in osteoclastogenesis. Here we investigated effects of PCI-32765, an oral and selective Btk inhibitor, on osteoclastogenesis as well as on multiple myeloma (MM) growth within the BM microenvironment. PCI-32765 blocked RANKL/M-CSF-induced phosphorylation of Btk and downstream PLC-γ2 in OCs, resulting in diminished TRAP5b (ED50 = 17 nM) and bone resorption activity. PCI-32765 also inhibited secretion of multiple cytokines and chemokines from OC and BM stromal cell cultures from both normal donors (ED50 = 0.5 nM) and MM patients. It decreased SDF-1-induced migration of MM cells, and down-regulated MIP1-α/CCL3 in MM cells. It also blocked MM cell growth and survival triggered by IL-6 or coculture with BM stromal cells or OCs in vitro. Importantly, PCI-32765 treatment significantly inhibits in vivo MM cell growth (P < .03) and MM cell-induced osteolysis of implanted human bone chips in SCID mice. Moreover, PCI-32765 prevents in vitro colony formation by stem-like cells from MM patients. Together, these results delineate functional sequelae of Btk activation mediating osteolysis and growth of MM cells, supporting evaluation of PCI-32765 as a novel therapeutic in MM.

Bruton tyrosine kinase (BTK) and its role in B-cell malignancy.

BTK is a kinase that functions downstream of multiple receptors in various hematologic cells. This review focuses on BTK-dependent pathways that are likely to be involved in maintaining the malignant phenotype in B-cell lymphomas and leukemias. Survival of various B-cell malignancies requires BTK-dependent signals from the B-cell antigen receptor. Survival is also dependent on malignant cells homing to and interacting with lymphoid microenvironments, and these interactions are also BTK-dependent due its role in signaling downstream of chemokine and innate immune receptors. The potential for therapeutic targeting of BTK is currently being tested in clinical settings.

Phase II studies of antiangiogenic four drug regimens for the treatment of advanced renal cell carcinoma: FUNIL-retinoid and the FUNIL-thalidomide protocols.

BACKGROUND AND PURPOSE: The objective of these studies was to determine the activity of two alternative 4- drug combinations using cis-retinoic acid or thalidomide administered with a previously developed combination of 5 fluorouracil, interferon-alpha, and interleukin 2 (FUNIL), for patients with metastatic renal cell carcinoma (RRC). METHODS: Patients enrolled in these studies had progressive measurable metastatic renal cell cancer and signed an informed consent. Treatments included continuous infusions of 5-fluorouracil, interferon-alpha, 6 MIU/m2 given subcutaneous on days 1, 3, and 5 every week, interleukin-2 6 MIU/m2/day given by continuous infusion days 2 to 5 every week, and either cis-retinoic acid at a dose of 1 mg/kg/day orally in two divided doses or thalidomide given at an initial dose of 200 mg per day. Each cycle consisted of 6 or 4 weeks of the combinations, respectively, followed by a 2-week rest. Patients were evaluated for response prior to each successive cycle. A 2-step mini-max statistical design was used. RESULTS: In the cis-retinoid study, 20 patients were enrolled. One patient was ineligible. There were 1 complete and 2 partial responses (one confirmed and one unconfirmed) (15.8%), 1 stable disease, and 15 disease progression. In the thalidomide combination study, 20 patients were enrolled, but only 19 are assessable. One patient progressed early and was never treated. There were 2 partial responses (10.5%), 4 stable disease, and 13 progressive disease. CONCLUSION: Neither the FUNIL-cis-retinoid nor the FUNIL-thalidomide regimens met their primary objective first step endpoint of 3 confirmed responses. Both regimens had significant adverse effects and neither is considered promising for further study.

A phase II study of thalidomide in advanced metastatic renal cell carcinoma.

OBJECTIVES: To evaluate the toxicity and activity of thalidomide in patients with advanced metastatic renal cell cancer and to measure changes of one angiogenic factor, vascular endothelial growth factor (VEGF)165, with therapy. PATIENTS AND METHODS: 29 patients were enrolled on a study of thalidomide using an intra-patient dose escalation schedule. Patients began thalidomide at 400 mg/d and escalated as tolerated to 1200 mg/d by day 54. Fifty-nine per cent of patients had had previous therapy with IL-2 and 52% were performance status 2 or 3. Systemic plasma VEGF165 levels were measured by dual monoclonal ELISA in 8 patients. RESULTS: 24 patients were evaluable for response with one partial response of 11 months duration of a patient with hepatic and pulmonary metastases (4%), one minor response, and 2 patients stable for over 6 months. Somnolence and constipation were prominent toxicities and most patients could not tolerate the 1200 mg/day dose level. Systemic plasma VEGF165 levels did not change with therapy. CONCLUSION: These results are consistent with a low level of activity of thalidomide in renal cell carcinoma. Administration of doses over 800 mg/day was difficult to achieve in this patient population, however lower doses were practical. The dose-response relationship, if any, of thalidomide for renal cell carcinoma is unclear.

Therapy-related myeloid leukemias are observed in patients with chronic lymphocytic leukemia after treatment with fludarabine and chlorambucil: results of an intergroup study, cancer and leukemia group B 9011.

PURPOSE: Patients with chronic lymphocytic leukemia (CLL) may have disease transformation to non-Hodgkin's lymphoma or prolymphocytic leukemia; however, development of therapy-related acute myeloid leukemia (t-AML) is unusual. A series of patients enrolled onto an intergroup CLL trial were examined for this complication. PATIENTS AND METHODS: A total of 544 previously untreated B-cell CLL patients were enrolled onto a randomized intergroup study comparing treatment with chlorambucil, fludarabine, or fludarabine plus chlorambucil. Case report forms from 521 patients were reviewed for t-AML. RESULTS: With a median follow-up of 4.2 years, six patients (1.2%) to date have developed therapy-related myelodysplastic syndrome (t-MDS; n = 3), t-AML (n = 2), or t-MDS evolving to t-AML (n = 1), from 27 to 53 months (median, 34 months) after study entry. This included five (3.5%) of 142 patients treated with fludarabine plus chlorambucil and one (0.5%) of 188 receiving fludarabine; no chlorambucil-treated patients developed t-MDS or t-AML (P =.007). At study entry, the median age among these six patients was 56 years (range, 44 to 72 years); three were male; the CLL Rai stage was I/II (n = 4) or III/IV (n = 2). Response to CLL therapy was complete (n = 4) or partial remission (n = 1) and stable disease (n = 1). Marrow cytogenetics, obtained in three of six cases at diagnosis of t-MDS or t-AML, were complex, with abnormalities in either or both chromosomes 5 and 7. Other abnormalities involved chromosomes X, 1, 8, 12, 17, and 19. Median survival after diagnosis of t-MDS/AML was 3.5 months (range, 0.5 to 10.1 months). CONCLUSION: Our findings raise the possibility that alkylator-purine analog combination therapy may increase the risk of therapy-related myeloid malignancies, which is of particular relevance with regard to ongoing trials using these combination therapies.

Analysis of age, estimated creatinine clearance and pretreatment hematologic parameters as predictors of fludarabine toxicity in patients treated for chronic lymphocytic leukemia: a CALGB (9011) coordinated intergroup study.

PURPOSE: Fludarabine is a renally excreted agent that is an effective treatment for chronic lymphocytic leukemia (CLL), a disease predominantly of the elderly. We sought to determine whether age, renal function or pretreatment hematologic status predicted toxicity of fludarabine treatment for CLL. METHODS: We evaluated 192 patients with previously untreated B-cell CLL who were entered onto the fludarabine treatment arm (25 mg/m(2) daily for 5 days every 28 days) of CALGB study 9011, an intergroup study with participation from SWOG, CTG/NCI-C and ECOG. Patients were required to have serum creatinine within 1.5 times normal. Hematologic indices and infections were recorded during the first 28-day cycle of treatment. A time-to-toxicity endpoint was evaluated over the entire course of fludarabine treatment. Creatinine clearance (CrCl(est)) was estimated using serum creatinine, age and body mass index. RESULTS: The median age was 64 years (range 37-87 years) and median CrCl(est) was 62 ml/min (range 27-162 ml/min, interquartile range 52-79 ml/min). We found no association between age and incidence of hematologic toxicity or infection during the first cycle of treatment. There was a strong association between CrCl(est) and the time-to-toxicity endpoint. Patients with CrCl(est) below 80 ml/min had increased incidence of toxicity during their treatment course ( P<0.0001). Pretreatment anemia, thrombocytopenia and Rai stage were highly associated with the incidence of neutrophil toxicity and grade III/IV hematologic toxicities during the first cycle of treatment ( P<0.0001). CONCLUSIONS: Patient age was not an independent risk factor for fludarabine-related toxicity, but CrCl(est) was associated with time to toxicity.