Recent advances in therapy of chronic lymphocytic leukaemia

The PKN1- TRAF1 signaling axis as a potential new target for chronic lymphocytic leukemia

TRAF1 is a pro-survival adaptor molecule in TNFR superfamily (TNFRSF) signaling. TRAF1 is overexpressed in many B cell cancers including refractory chronic lymphocytic leukemia (CLL). Little has been done to assess the role of TRAF1 in human cancer. Here we show that the protein kinase C related kinase Protein Kinase N1 (PKN1) is required to protect TRAF1 from cIAP-mediated degradation during constitutive CD40 signaling in lymphoma. We show that the active phospho-Thr774 form of PKN1 is constitutively expressed in CLL but minimally detected in unstimulated healthy donor B cells. Through a screen of 700 kinase inhibitors, we identified two inhibitors, OTSSP167, and XL-228, that inhibited PKN1 in the nanomolar range and induced dose-dependent loss of TRAF1 in RAJI cells. OTSSP167 or XL-228 treatment of primary patient CLL samples led to a reduction in TRAF1, pNF-κB p65, pS6, pERK, Mcl-1 and Bcl-2 proteins, and induction of activated caspase-3. OTSSP167 synergized with venetoclax in inducing CLL death, correlating with loss of TRAF1, Mcl-1, and Bcl-2. Although correlative, these findings suggest the PKN1-TRAF1 signaling axis as a potential new target for CLL. These findings also suggest the use of the orally available inhibitor OTSSP167 in combination treatment with venetoclax for TRAF1 overexpressing CLL.

Rapid improvement in symptoms and physical function following ibrutinib initiation in chronic lymphocytic leukemia and the associated changes in plasma cytokines

A prospective pilot study was carried out on 34 CLL patients treated with ibrutinib, evaluating the effects on symptoms and physical function with changes in plasma exosomes (EXs), β2-microglobulin (β2M) and 26 plasma cytokines. The revised Edmonton Symptom Assessment Scale (ESAS-R) demonstrated moderate fatigue, shortness of breath and a sense of unwellness before treatment, which significantly improved within 2 weeks of starting ibrutinib. These changes were associated with a rapid improvement in sit-to-stand and 4 m walking speeds. The plasma levels of CCL11, IL-7, -8 and -10 dropped initially while the levels of TNF-α/-β, CCL3, CCL4, CCL17, and IL-16 continued to decline for 12 months. Despite the initial lymphocytosis, plasma β2M levels fell but no consistent change in plasma EXs occurred. Thus, ibrutinib can produce a rapid and sustained improvement in symptoms and physical function in CLL, associated with a decline in multiple plasma cytokines.

Fludarabine-resistance associates with ceramide metabolism and leukemia stem cell development in chronic lymphocytic leukemia

Fludarabine (flu) -containing regimens such as flu, cyclophosphamide and rituximab have been established as one of the standard first line therapy in medically-fit chronic lymphocytic leukemia (CLL) patients. Therefore, flu-refractory (primary flu-insensitivity or flu-caused relapse) remains a major problem causing treatment failure for CLL patients. We isolated the peripheral blood mononuclear cells (PBMCs) from CLL patients and treated with flu to find flu-refractory cases, and established flu-resistant clonal cells to study molecular mechanism of flu-resistance. By comparing parental MEC-2 cells, a human CLL cell line, we found that flu-resistant clonal cells were significantly increased lethal dose 50 of flu concentration, and up-regulated expression of P-glycoprotein, a drug-resistant marker, glucosylceramide synthase (GCS), an enzyme that can convert ceramide to glucosylceramide, and CD34, a leukemia stem cell marker. Overexpression of GCS leads to promptly elimination of cellular ceramide levels and accumulation of glucosylceramide, which reduces apoptosis and promotes survival and proliferation of flu-resistant clonal cells. Furthermore, we demonstrated that the accumulation of glucosylceramide can be blocked by PDMP to restore flu-sensitivity in flu-resistant clonal cells. We also found that elevating glucosylceramide levels in flu-resistant clonal cells was associated with up-regulation of GCS and CD34 expression. Importantly, overexpression of GCS or CD34 was also determined in flu-refractory PBMCs. Our results show that flu-resistance is associated with the alteration of ceramide metabolism and the development of leukemia stem cell-like cells. The flu-resistance can be reversed by GCS inhibition as a novel strategy for overcoming drug resistance.

Ailanthone induces autophagic and apoptotic cell death in human promyelocytic leukemia HL-60 cells

Ailanthone, which is extracted from the traditional Chinese medicinal plant Ailanthus altissima, has been thoroughly demonstrated to have anti-tumor, anti-HIV, anti-inflammatory, anti-malarial, anti-allergic and anti-microbial activities. However, the anti-proliferative effects of ailanthone on HL-60 cells and potential mechanisms underlying those effects have not been reported. In the present study, we demonstrated the potent cytotoxicity of ailanthone against HL-60 cells. Annexin V-APC/7-ADD staining assay indicated that ailanthone increased the number of apoptotic cells in a dose-dependent manner. PI staining showed that ailanthone increased the percentage of G0/G1-phase cells in a dose-dependent manner. Acridine orange staining suggested that ailanthone induced the formation of acidic vesicular organelles in HL-60 cells and pretreatment with BaF-A1 could attenuate this process. Western blotting showed that ailanthone up-regulated the protein expression levels of beclin-1 and LC3-II and down-regulated those of LC3-I and p62 in a dose-dependent manner. Use of BaF-A1 showed that the anti-proliferative effects of ailanthone on HL-60 cells may be partly attributable to the induction of autophagy-mediated apoptosis by MTT assay and annexin V-APC/7-ADD staining assay.

Efficient lysis of B-chronic lymphocytic leukemia cells by the plant-derived sesquiterpene alcohol α-bisabolol, a dual proapoptotic and antiautophagic agent

The sesquiterpene α-bisabolol (α-BSB) is a cytotoxic agent against acute leukemia and chronic myeloid leukemia cells. Here the profile of α-BSB citotoxicity was evaluated ex vivo in primary mononuclear blood cells isolated from 45 untreated B-chronic lymphocytic leukemia (B-CLL) patients. We studied the effects of α-BSB by flow cytometric and western blotting techniques with the following findings: (1) α-BSB was an effective proapoptotic agent against B-CLL cells (IC50 42 ± 15 μM). It was also active, but to a lesser extent, on normal residual B cells and monocytes (IC50 68 ± 34 and 74 ± 28 μM, respectively; p < 0.01), while T-cells, though not achieving IC50, were nevertheless decreased. (2) Lipid raft content positively correlated with α-BSB cell sensitivity, while neither the phenotype of B-CLL cells nor the disease clinical stage did affect the sensitivity to α-BSB. (3) Flow cytometry analysis evidenced the induction of pores in mitochondrial and lysosomal membrane after 3- to 5-hour exposure of B-CLL cells to α-BSB, leading to apoptosis; in contrast, western blotting analysis showed inhibition of the autophagic flux. Therefore, according to cellular selectivity, α-BSB is a cytotoxic agent preferentially active against leukemic cells, while its lower activity on normal B cells, monocytes and T cells may account for an additive anti-inflammatory effect targeting the leukemia-associated pro-inflammatory microenvironment. Consistent with the observed effects on intracellular processes, α-BSB should be regarded as a dual agent, both activating mitochondrial-based apoptosis and inhibiting autophagy by disrupting lysosomes.

Changes in T-cell subpopulations and cytokine network during early period of ibrutinib therapy in chronic lymphocytic leukemia patients: the significant decrease in T regulatory cells number

B cell receptor (BCR) stimulation signal plays an important role in the pathogenesis of chronic lymphocytic leukemia (CLL), and kinase inhibitors directed toward the BCR pathway are now the promising anti-leukemic drugs. Ibrutinib, a Bruton tyrosine kinase inhibitor, demonstrates promising clinical activity in CLL. It is reported that ibrutinib, additionally to directly targeting leukemic cells, also inhibits the interactions of these cells with T cells, macrophages and accessory cells. Assessment of these mechanisms is important because of their non -direct anti-leukemic effects and to identify possible side effects connected with long-term drug administration.

The aim of this study was to assess the in vivo effects of ibrutinib on T-cell subpopulations and cytokine network in CLL. The analysis was performed on a group of 19 patients during first month of ibrutinib therapy. The standard multicolor flow cytometry and cytometric bead array methods were used for assessment of T-cell subsets and cytokines/chemokines, respectively.

The data obtained indicates that Ibrutinib treatment results in changes in T-cell subpopulations and cytokine network in CLL patients. Particularly, a significant reduction of T regulatory cells in peripheral blood was observed. By targeting these populations of T cells Ibrutinib can stimulate rejection of tumor cells by the immune system.

Rituximab maintenance versus observation following abbreviated induction with chemoimmunotherapy in elderly patients with previously untreated chronic lymphocytic leukaemia (CLL 2007 SA): an open-label, randomised phase 3 study

BACKGROUND

Most patients with chronic lymphocytic leukaemia relapse after initial therapy combining chemotherapy with rituximab. We assessed the efficacy and safety of rituximab maintenance treatment versus observation for elderly patients in remission after front-line abbreviated induction by fludarabine, cyclophosphamide, and rituximab (FCR).

METHODS

This randomised, open-label, multicentre phase 3 trial at 89 centres in France enrolled treatment-naive and fit patients aged 65 years or older with chronic lymphocytic leukaemia without del(17p). Eligible patients had an Eastern Cooperative Oncology Group performance status of 0-1 and adequate renal and hepatic function. Patients in response to complete induction treatment with four monthly courses of full-dose FCR with two interim rituximab doses on day 14 of cycles 1 and 2 (oral fludarabine [40 mg/m² per day] and oral cyclophosphamide [250 mg/m² per day] for the first 3 days of each cycle, rituximab at 375 mg/m² intravenously on day 0 of cycle 1 and subsequently at 500 mg/m² on day 14 of cycle 1, days 1 and 14 of cycle 2, and day 1 of cycles 3 and 4) were eligible for randomisation. Recovery from FCR toxicity and patient willingness to continue the trial were mandatory. We randomly assigned (1:1) patients to either receive intravenous rituximab (500 mg/m²) every 8 weeks for up to 2 years or undergo observation, with a central computer-generated randomisation list using randomly permuted blocks of variable sizes. Randomisation was stratified by IGHV mutational status, the presence or absence of del(11q), and response level to induction treatment. The primary endpoint was progression-free survival, with the objective to assess the superiority of rituximab maintenance relative to observation. The final analysis was done in the intention-to-treat population. Safety was analysed in all patients who received at least one dose of study drug in the rituximab group and in all patients in the observation group. This trial is closed to accrual whilst continuing patient follow-up. The study is registered with ClinicalTrials.gov, number NCT00645606.

FINDINGS

Between Dec 14, 2007, and Feb 18, 2014, 542 patients were enrolled, of whom 525 started FCR induction. Between June 10, 2008, and Aug 14, 2014, 409 (78%) patients were randomly assigned to rituximab maintenance (n=202) or observation (n=207). Four (2%) patients in the rituximab group did not receive the allocated treatment (progressive disease [n=1], adverse events [n=3]). After a median follow-up of 47·7 months (IQR 30·4-65·8), median progression-free survival in the rituximab group (59·3 months, 95% CI 49·6-not estimable) was improved compared with the observation group (49·0 months, 39·9-60·5; hazard ratio 0·55, 95% CI 0·40-0·75; p=0·0002). Neutropenia and grade 3-4 infections were more common with rituximab maintenance (105 [53%] of 198 patients vs 74 [36%] of 207 patients and 38 [19%] vs 21 [10%], respectively) during the study. The most common grade 3-4 infection was lower respiratory tract infection (24 [12%] vs eight [4%]). The incidence of second cancers, except basal cell carcinoma, was similar in both groups (29 [15%] vs 23 [11%]). Deaths were related to adverse events for 23 (11%) patients in the rituximab group and 16 (8%) in the observation group.

INTERPRETATION

2-year maintenance rituximab in selected elderly patients improves progression-free survival and shows an acceptable safety profile. Immunotherapy maintenance strategy is a relevant option in front-line treatment of chronic lymphocytic leukaemia, even in the age of targeted therapy.

FUNDING

French National Cancer Institute (INCa), Roche, Chugai.

Lck is a relevant target in chronic lymphocytic leukaemia cells whose expression variance is unrelated to disease outcome

Pathogenesis of chronic lymphocytic leukaemia (CLL) is contingent upon antigen receptor (BCR) expressed by malignant cells of this disease. Studies on somatic hypermutation of the antigen binding region, receptor expression levels and signal capacity have all linked BCR on CLL cells to disease prognosis. Our previous work showed that the src-family kinase Lck is a targetable mediator of BCR signalling in CLL cells, and that variance in Lck expression associated with ability of BCR to induce signal upon engagement. This latter finding makes Lck similar to ZAP70, another T-cell kinase whose aberrant expression in CLL cells also associates with BCR signalling capacity, but also different because ZAP70 is not easily pharmacologically targetable. Here we describe a robust method of measuring Lck expression in CLL cells using flow cytometry. However, unlike ZAP70 whose expression in CLL cells predicts prognosis, we find Lck expression and disease outcome in CLL are unrelated despite observations that its inhibition produces effects that biologically resemble the egress phenotype taken on by CLL cells treated with idelalisib. Taken together, our findings provide insight into the pathobiology of CLL to suggest a more complex relationship between expression of molecules within the BCR signalling pathway and disease outcome.

Angiomodulators in cancer therapy: New perspectives

The formation of new blood vessels plays a crucial for the development and progression of pathophysiological changes associated with a variety of disorders, including carcinogenesis. Angiogenesis inhibitors (anti-angiogenics) are an important part of treatment for some types of cancer. Some natural products isolated from marine invertebrates have revealed antiangiogenic activities, which are diverse in structure and mechanisms of action. Many preclinical studies have generated new models for further modification and optimization of anti-angiogenic substances, and new information for mechanistic studies and new anti-cancer drug candidates for clinical practice. Moreover, in the last decade it has become apparent that galectins are important regulators of tumor angiogenesis, as well as microRNA. MicroRNAs have been validated to modulate endothelial cell migration or endothelial tube organization. In the present review we summarize the current knowledge regarding the role of marine-derived natural products, galectins and microRNAs in tumor angiogenesis.

Idelalisib and caffeine reduce suppression of T cell responses mediated by activated chronic lymphocytic leukemia cells

Chronic lymphocytic leukemia (CLL) is associated with T cell dysfunction. Activated CLL cells are found within the lymphoid tumor micro-environment and overcoming immuno-suppression induced by these cells may improve anti-CLL immune responses. However, the mechanisms by which activated CLL cells inhibit T cell responses, and reagents targeting such mechanisms have not been identified. Here we demonstrate that the ability of in vitro activated CLL cells to suppress T cell proliferation is not reversed by the presence of ecto-nuclease inhibitors or blockade of IL-10, PD-1 and CTLA-4 pathways. Caffeine is both an adenosine receptor antagonist and a phosphatidylinositol-3-kinase, p110δ (PI3Kδ) inhibitor and, at physiologically relevant levels, significantly reversed suppression. Significant reversal of suppression was also observed with the PI3Kδ specific inhibitor Idelalisib but not with adenosine receptor specific antagonists. Furthermore, addition of caffeine or Idelalisib to activated CLL cells significantly inhibited phosphorylation of AKT, a downstream kinase of PI3K, but did not affect CLL viability. These results suggest that caffeine, in common with Idelalisib, reduces the immuno-suppressive activity of activated CLL cells by inhibiting PI3Kδ. These findings raise the possibility that these compounds may provide a useful therapeutic adjunct by reducing immuno-suppression within the tumor micro-environment of CLL.

Differences in treatment goals and perception of symptom burden between patients with myeloproliferative neoplasms (MPNs) and hematologists/oncologists in the United States: Findings from the MPN Landmark survey

BACKGROUND

This analysis of the myeloproliferative neoplasm (MPN) Landmark survey evaluated gaps between patient perceptions of their disease management and physician self-reported practices.

METHODS

The survey included 813 patient respondents who had MPNs (myelofibrosis [MF], polycythemia vera [PV], or essential thrombocythemia [ET]) and 457 hematologist/oncologist respondents who treated patients with these conditions.

RESULTS

Greater proportions of physician respondents reported using prognostic risk classifications (MF, 83%; PV, 59%; ET, 77%) compared with patient recollections (MF, 54%; PV, 17%; ET, 31%). Most physician respondents reported that their typical symptom assessments included asking patients about the most important symptoms or a full list of symptoms, whereas many patient respondents reported less specific assessments (eg, they were asked how they were feeling). Many patient respondents did not recognize common symptoms as MPN-related. For example, approximately one-half or more did not believe difficulty sleeping resulted from their MPN (MF, 49%; PV, 64%; ET, 76%). Physician respondents underestimated the proportion of patients who had symptomatic PV or ET at diagnosis compared with patient respondents. There was discordance regarding treatment goals: among patient respondents with MF or PV, "slow/delay progression of condition" was the most important treatment goal, whereas physician respondents reported "symptom improvement" and "prevention of vascular/thrombotic events," respectively. Finally, more than one-third of patient respondents were not "very satisfied" with their physician's overall management/communication.

CONCLUSIONS

The care and satisfaction of patients with MPN may be improved with increased patient education and improved patient-physician communication. Cancer 2017;123:449-458. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.