Functional impact of NOTCH1 mutations in chronic lymphocytic leukemia

The purpose of this study was to compare the expression and function of NOTCH1 in chronic lymphocytic leukemia (CLL) patients harboring a wild-type (WT) or mutated NOTCH1 gene. NOTCH1 mRNA and surface protein expression levels were independent of the NOTCH1 gene mutational status, consistent with the requirement for NOTCH1 signaling in this leukemia. However, compared with NOTCH1-WT CLL, mutated cases displayed biochemical and transcriptional evidence of an intense activation of the NOTCH1 pathway. In vivo, expression and activation of NOTCH1 was highest in CLL cells from the lymph nodes as confirmed by immunohistochemistry. In vitro, the NOTCH1 pathway was rapidly downregulated, suggesting that signaling relies upon micro-environmental interactions even in NOTCH1-mutated cases. Accordingly, co-culture of Jagged1(+) (the NOTCH1 ligand) nurse-like cells with autologous CLL cells sustained NOTCH1 activity over time and mediated CLL survival and resistance against pro-apoptotic stimuli, both abrogated when NOTCH1 signaling was pharmacologically switched off. Together, these results show that NOTCH1 mutations have stabilizing effects on the NOTCH1 pathway in CLL. Furthermore, micro-environmental interactions appear critical in activating the NOTCH1 pathway both in WT and mutated patients. Finally, NOTCH1 signals may create conditions that favor drug resistance, thus making NOTCH1 a potential molecular target in CLL.

Long-term outcomes of primary ocular adnexal lymphoma treatment with intraorbital rituximab injections

PURPOSE

We recently reported on the efficacy of intralesional rituximab for treating primary ocular adnexal lymphoma in a pilot study. After treatment, a complete response was observed in two of five patients, a partial response in one patient, and lesion recurrence in two patients. In this study, we evaluate the long-term follow-up of the five previously treated patients as well as the response of two new patients to an augmented dose of rituximab.

METHODS

We followed up the five patients who were treated with rituximab during the initial pilot study. Two additional patients were also enrolled and treated with four intraorbital injections of 10 mg rituximab once a week for 1 month (total dose of 40 mg). Median follow-up period was 4 years for the first five patients and 1 year for the last two patients.

RESULTS

Lymphoma did not relapse in the two patients who originally responded immediately to treatment. Of the initial partial responders, one became disease-free after additional rituximab treatment, and one experienced a standardized uptake value reduction, as measured with positron emission tomography-CT. One patient who experienced abdominal and pulmonary localization 7 months later showed no local recurrence. The two newly enrolled patients had complete remission after the first cycle of treatment and no disease recurrence eight and 11 months later, respectively.

CONCLUSIONS

This study suggests that intralesional administration of rituximab for treating localized ocular adnexal CD20+ lymphomas could be an effective front-line therapeutic option with negligible side effects and a good response rate and duration.

Abstract 2302: The extracellular form of NAMPT contributes to creating a proinflammatory environment in chronic lymphocytic leukemia

Malignant cells are characterized by a higher NAD turnover rate than normal cells, making this biosynthetic pathway an attractive target for cancer treatment. Increasing evidence indicate that NAD plays important roles not only in energy metabolism, but also in calcium homeostasis and inflammation. Here we investigated the biologic significance of a rate-limiting enzyme of the NAD synthesis pathway, nicotinamide phosphoribosyl transferase (NAMPT), focusing our attention on the extracellular form (eNAMPT), which exerts cytokine/adipokine-like actions in different tumor models as well as in acute and chronic inflammatory-metabolic diseases. The role of eNAMPT and its mechanisms of action have been addressed in chronic lymphocytic leukemia (CLL), an indolent lymphoproliferative disorder, strongly dependent on a growth supportive environment and on nucleotide/nucleoside metabolism. The aim of this work is to test whether eNAMPT plays a role in shaping the leukemic environment, by generating proinflammatory conditions that favor tumor expansion.

Results indicated that: i) B-CLL lymphocytes expressed higher levels of NAMPT mRNA compared to normal B lymphocytes obtained from age- and sex-matched donors; ii) plasma levels of eNAMPT were also significantly higher in CLL patients (n=80) compared to controls (n=20); and iii) activation of purified CLL cells was followed by eNAMPT secretion, indicating that it is the leukemic component that actively releases eNAMPT. Then we addressed the question whether this cytokine may play an active role in the leukemic microenvironment. Treatment of PBMCs, but not B purified CLL lymphocytes, for 5 days with recombinant NAMPT resulted in an increased numbers of adherent cells (CD11b+), displaying intracellular vacuoles and granules, consistent with macrophage differentiation, and in significant induction and secretion of proinflammatory cytokines. Furthermore, long-term exposure to eNAMPT enhanced the formation and the phagocytosis ability of nurse-like cells (NCLs), a CD68+ myeloid population and an essential component of the CLL microenvironment. Moreover, treatment of NLCs with eNAMPT triggered rapid phosphorylation of Erk1/2, STAT3 and nuclear translocation of the NF-kB component p65. Lastly, preliminary data indicated that NAMPT enzymatic activity is not required for its extracellular functions, as highlighted by the inability of i) nicotinamide mononucleotide (NMN), a product of the NAMPT activity, to induce STAT3 phosphorylation and cytokines secretion, as well as ii) NAMPT inhibitor FK866 to block eNAMPT-dependent STAT3 activation.

Taken together, these data support the hypothesis that eNAMPT, secreted by CLL cells, contributes to the formation of a proinflammatory environment, driving recruitment and differentiation of myeloid populations, that provides anti-apoptotic and pro-survival signals to leukemic cells.

Citation Format: Valentina Audrito, Sara Serra, Tiziana Vaisitti, Nadia Raffaelli, Luca Laurenti, Giovanni D'Arena, Davide Rossi, Gianluca Gaidano, Menico Rizzi, Silvia Deaglio. The extracellular form of NAMPT contributes to creating a proinflammatory environment in chronic lymphocytic leukemia. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2302. doi:10.1158/1538-7445.AM2013-2302

The PD-1/PD-L1 axis contributes to T-cell dysfunction in chronic lymphocytic leukemia

Chronic lymphocytic leukemia is marked by profound defects in T-cell function. Programmed death-1 is a receptor involved in tumor-mediated immunosuppression through binding of the PD-L1 ligand. Multiparametric flow cytometry and immunohistochemistry were used to study PD-1/PD-L1 expression. Functional assays were used to determine the involvement of the PD-1/PD-L1 axis in T-cell responses. PD-1 expression by CD4(+) and CD8(+) T lymphocytes was significantly higher in 117 chronic lymphocytic leukemia patients than in 33 donors of a comparable age. CD4(+) and CD8(+) T lymphocytes from chronic lymphocytic leukemia patients displayed increased numbers of effector memory and terminally differentiated cells, respectively, when compared to controls. The number of effector memory CD4(+) and terminally differentiated CD8(+) lymphocytes positively associated with a more advanced stage of disease, treatment requirements and unfavorable genomic aberrations. Furthermore, leukemic lymphocytes expressed higher levels of PD-L1 than circulating B lymphocytes from normal donors. PD-1 and PD-L1 surface expression spiked in proliferating T and B lymphocytes, suggesting that this interaction works efficiently in activated environments. Within chronic lymphocytic leukemia proliferation centers in the lymph node, CD4(+)/PD-1(+) T lymphocytes were found to be in close contact with PD-L1(+) chronic lymphocytic leukemia cells. Lastly, functional experiments using recombinant soluble PD-L1 and blocking antibodies indicated that this axis contributes to the inhibition of IFN-γ production by CD8(+) T cells. These observations suggest that pharmacological manipulation of the PD-1/PD-L1 axis may contribute to restoring T-cell functions in the chronic lymphocytic leukemia microenvironment.

B-cell receptor configuration and adverse cytogenetics are associated with autoimmune hemolytic anemia in chronic lymphocytic leukemia

The development of autoimmune hemolytic anemia (AIHA) in patients with chronic lymphocytic leukemia (CLL) is associated with specific biological features. The occurrence of AIHA was hereby investigated in a retrospective series of 585 CLL patients with available immunoglobulin heavy chain variable (IGHV) gene status. AIHA occurred in 73 patients and was significantly associated with an IGHV unmutated (UM) status (P < 0.0001) and unfavorable [del(17)(p13) and del(11)(q23)] cytogenetic lesions (P < 0.0001). Stereotyped HCDR3 sequences were identified in 29.6% of cases and were similarly represented among patients developing or not AIHA; notably, subset #3 was associated with a significantly higher risk of AIHA than the other patients (P = 0.004). Multivariate analysis showed that UM IGHV, del(17)(p13) and del(11)(q23), but not stereotyped subset #3, were the strongest independent variables associated with AIHA. Based on these findings, we generated a biological risk score for AIHA development according to the presence of none (low risk), one (intermediated risk), or two (high risk) of the independent risk factors. Overall, our data indicate that UM IGHV status and/or unfavorable cytogenetic lesions are associated with the risk of developing secondary AIHA in CLL patients and suggest a possible role of specific stereotyped B-cell receptor subsets in a proportion of cases.

Role of 18F-FDG PET-CT for evaluating the response to reduced-intensity conditioning allogeneic transplant in heavily pre-treated patients with chronic lymphocytic leukemia: preliminary results in nine patients

OBJECTIVE

The aim of our preliminary study was to evaluate the potential role of 18F-FDG PET-CT in monitoring response to reduced-intensity conditioning (RIC) transplant in a small series of chronic lymphocytic leukemia (CLL) patients and to compare the results with those obtained by standard criteria.

METHODS

We retrospectively analyzed 9 consecutive refractory/relapsed CLL patients, who underwent RIC transplant from March 2004 until May 2009. PET-CT was planned at 6-8 months after transplant to assess response and at a mean of 6 months during follow-up. The mean long-term follow-up period was 38 months (range 12-74 months, median 29 months).

RESULTS

The first PET-CT showed abnormal 18F-FDG uptake in five patients, while by standard criteria eight patients showed persistent disease. At the end of follow-up (mean 38 months), all four patients with previously negative scan were still PET negative and in complete remission by standard criteria. All five patients with previously positive scan were still PET positive: one patient died for disease progression and four are alive with disease.

CONCLUSIONS

Our preliminary data, although in a small series of CLL patients, suggest that the metabolic findings revealed at first PET-CT after transplant seem to predict the patient outcome and to assess the metabolic disease status earlier than clinical evaluation by standard criteria. PET-CT performed during follow-up may be useful to early detect disease progression.

Efficacy of lenalidomide plus dexamethasone for POEMS syndrome relapsed after autologous peripheral stem-cell transplantation

POEMS syndrome is a rare paraneoplastic condition associated to an underlying plasmacellular dyscrasia. The pathogenesis of POEMS is poorly understood, but overproduction of VEGF, probably secreted by clonal plasma cells, is thought to be responsible for the signs and symptoms of the syndrome, and it seems to be useful for the monitoring of the response to therapy. At present, an effective therapeutic option for the patients is represented by autologous peripheral blood stem-cell transplantation (aPBSCT), although relapses have been described, and there is an important morbidity associated with this procedure. Before the implementation of aPBSCT, the clinical course of POEMS syndrome was characterized by progressive polyneuropathy potentially leading to death for respiratory failure. Given the high serum and plasma levels of VEGF observed in POEMS patients, the use of anti-angiogenetic drugs such as thalidomide and lenalidomide and other drugs with anti-VEGF and anti-TNF effect such as bortezomib have been considered to treat this syndrome. There are evidences of lenalidomide benefit in both front-line and previously treated patients, but scanty data are available about its use for relapse after aPBSCT. Here, we report the successful use of lenalidomide in a patient who relapsed after aPBSCT.

A shorter time to the first treatment may be predicted by the absolute number of regulatory T-cells in patients with Rai stage 0 chronic lymphocytic leukemia

Regulatory T-cells (Tregs) are increased in chronic lymphocytic leukemia(CLL) and correlates with clinical and biological features of active/progressive disease. However, little is known about their ability to predict the time to first treatment (TFT). We evaluated 75 patients with Rai stage 0 CLL, in whom the absolute number of Tregs was determined at diagnosis, and correlated to main clinical and biological features, as well as to the need of receiving any specific therapy during the course of the disease. After a median follow-up of 30 months, 12 patients(16%) required therapy at some time from the diagnosis. Treated patients showed a significant higher number of peripheral white blood cells and B-lymphocytes, platelet count, cases with unmutated immunoglobulin heavy chain status, and high-risk cytogenetic abnormalities,as well as lower hemoglobin values, than patients who did not need therapy. A greater number of circulating Tregs was detected in treated patients (P < 0.001). Multivariate analysis confirmed that the absolute number of Tregs was an independent predictor of TFT in these patients, the best predictive cut-off being 41/mL. These data show that the absolute Tregs cell number is able to identify Rai stage 0 CLL patients at higher risk of requiring therapy.

Abstract 1348: CD38 regulates homing and engraftment in a mouse model of CLL

Chronic lymphocytic leukemia (CLL) is the result of a dynamic balance between proliferating cells in lymphoid organs and circulating cells resisting apoptosis. A critical step in the maintenance and progression of the disease is the re-circulation of leukemic cells from blood to growth-permissive niches. This process is controlled by a set of surface molecules expressed by CLL cells and modulated in response to environmental conditions. We previously showed that CD38, an enzyme and a receptor, functionally cooperates with the CXCL12/CXCR4 axis, increasing the ability of CLL cells to home to bone marrow and lymph nodes. Moreover, the use of anti-CD38 mAbs influences this cooperation, enhancing or impairing the chemotactic behavior of the neoplastic cells. New evidence also indicates that CD38 synergizes with the CD49d integrin, increasing adhesion of CLL cells to VCAM-1 or the CS-1 fibronectin fragment, two known ligands of CD49d. To complete the picture, CD38 expression marks a CLL subset with increased activity of MMP-9, the main matrix metalloproteinase expressed by CLL cells. Ligation of CD38 with specific antibodies increases MMP-9 secretion and hence the invasive properties of CLL cells. The effects on chemotaxis, adhesion and invasion are obtained through the modulation of a ERK1/2-dependent, PI-3K-independent pathway. The aim of this work is to confirm in an in vivo model the role played by CD38 in regulating CLL homing to specific niches and engraftment ability of leukemic cells. The CLL-like cell line Mec-1, constitutively CD38-/CD49d+, was compared to transfectants, generated both by lentiviral infections and by electroporation, stably expressing wild-type CD38, as well a mutant lacking enzyme activities. An in vivo model of immune-compromised mice was set-up, using the NOD/SCID/γ chain-/- (NSG) mice. Tumor cells were injected into the tail vein of 10-12 weeks old mice and left to engraft for 4 weeks. Results indicate that de novo expression of CD38 by Mec-1 cells increases growth kinetics in vivo with a higher proliferation rate and metastatic potential, as compared to the Mec-1 mock- cells. Mice injected with CD38+ Mec-1 cells show earlier signs of tumor burden and die sooner. Both these features are lost when the animals are injected with the enzyme-deficient variant of CD38, suggesting that the enzymatic activity is critical for in vivo growth and re-circulation of Mec-1 cells. Microarray data confirm that the genetic signature of the CD38-enzyme mutant overlaps with the wild-type cell line, clearly distinct from cells transfected with CD38. The latter cell line shows up-modulation of several genes involved in chemotaxis and adhesion. These results support the working hypothesis that CD38 is part of a complex network of molecules and signals, that regulate homing of leukemic cells to growth-permissive niches and represent the rationale for testing the in vivo impact of anti-CD38 mAbs or enzyme inhibitors as potential therapeutic tools.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1348. doi:1538-7445.AM2012-1348

Abstract 5170: Metabolism and cancer: The CD38-NAMPT connection in chronic lymphocytic leukemia

Tumor transformation is generally accompanied by an altered metabolic state, with higher needs for NAD, an essential co-factor in the oxidative phosphorylation chain, as well as a substrate for four classes of enzymes, including the NADase CD38. In leukocytes, NAD is synthesized mainly from nicotinamide through the activity of nicotinamide phosphoribosyl transferase (NAMPT), which is the first and rate-limiting enzyme in this biosynthesis pathway. In addition to its intracellular localization (iNAMPT form), the enzyme can be present extracellularly (eNAMPT), where it exerts cytokine-like actions that promote the maturation of early stage B cells. For this reason it is also known as pre-B cell colony enhancing factor (PBEF). Our hypothesis is that PBEF/Nampt exerts pro-survival activity in human leukemic B cells through the generation of a pro-inflammatory microenvironment. The model selected is chronic lymphocytic leukemia (CLL), a disease characterized by the slowly progressive expansion of mature CD5+ B lymphocytes, intrinsically resistant to apoptosis and dependent on a growth supportive environment for progression. A further reason for selecting this model is that CD38 is an independent negative prognostic marker for CLL patients, suggesting that modulation of the extracellular NAD/nicotinamide balance is critical in determining a more aggressive phenotype. Analysis of the expression of i and eNAMPT shows that CLL cells (n=60) express high and homogeneous levels of iNAMPT comparable with those scored by normal B lymphocytes from peripheral blood of health donors. In contrast, plasma eNAMPT levels are significantly higher (fourfold increased, p=0.001) in CLL patients (n=50) when compared to controls. These data suggest an involvement of eNAMPT in this disease, also confirmed by in vitro experiments where CLL cells, cultured in the presence of recombinant eNAMPT, showed activation and proliferation. Furthermore, after 5 days of treatment with eNAMPT CLL cells displayed morphological features of immunoblasts, as observed after activation of CD38 using a combination of agonistic mAbs and IL-2. In line with our hypothesis of a direct interplay between CD38 and eNAMPT, i) CD38+ CLL cells were selectively responsive to eNAMPT actions and ii) CD38 activation led to a potent and reproducible increase in eNAMPT. Combined treatment of CLL cells with agonistic anti-CD38/IL-2 was followed by i) a rapid increased of NAMPT mRNA and ii) a marked secretion of eNAMPT, present in culture supernatants after 5 days of treatment. No difference was observed in iNAMPT levels, constantly elevated. Considered together, these data suggest the existence of a CD38/eNAMPT extracellular loop, where CD38 consumes NAD and generates nicotinamide, triggering eNAMPT expression and activation to reconstitute extracellular NAD levels. This loop appears to be operative in CLL cells, generating pro-survival and activation signals.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5170. doi:1538-7445.AM2012-5170

The Aurora A and B kinases are up-regulated in bone marrow-derived chronic lymphocytic leukemia cells and represent potential therapeutic targets

BACKGROUND

The malignant B cells in chronic lymphocytic leukemia receive signals from the bone marrow and lymph node microenvironments which regulate their survival and proliferation. Characterization of these signals and the pathways that propagate them to the interior of the cell is important for the identification of novel potential targets for therapeutic intervention.

DESIGN AND METHODS

We compared the gene expression profiles of chronic lymphocytic leukemia B cells purified from bone marrow and peripheral blood to identify genes that are induced by the bone marrow microenvironment. Two of the differentially expressed genes were further studied in cell culture experiments and in an animal model to determine whether they could represent appropriate therapeutic targets in chronic lymphocytic leukemia.

RESULTS

Functional classification analysis revealed that the majority of differentially expressed genes belong to gene ontology categories related to cell cycle and mitosis. Significantly up-regulated genes in bone marrow-derived tumor cells included important cell cycle regulators, such as Aurora A and B, survivin and CDK6. Down-regulation of Aurora A and B by RNA interference inhibited proliferation of chronic lymphocytic leukemia-derived cell lines and induced low levels of apoptosis. A similar effect was observed with the Aurora kinase inhibitor VX-680 in primary chronic lymphocytic leukemia cells that were induced to proliferate by CpG-oligonucleotides and interleukin-2. Moreover, VX-680 significantly blocked leukemia growth in a mouse model of chronic lymphocytic leukemia.

CONCLUSIONS

Aurora A and B are up-regulated in proliferating chronic lymphocytic leukemia cells and represent potential therapeutic targets in this disease.

IGHV gene mutational status and 17p deletion are independent molecular predictors in a comprehensive clinical-biological prognostic model for overall survival prediction in chronic lymphocytic leukemia

Background

Prognostic index for survival estimation by clinical-demographic variables were previously proposed in chronic lymphocytic leukemia (CLL) patients. Our objective was to test in a large retrospective cohort of CLL patients the prognostic power of biological and clinical-demographic variable in a comprehensive multivariate model. A new prognostic index was proposed.

Methods

Overall survival and time to treatment in 620 untreated CLL patients were analyzed retrospectively to evaluate the multivariate independence and predictive power of mutational status of immunoglobulin heavy chain variable gene segments (IGHV), high-risk chromosomal aberration such as 17p or 11q deletions, CD38 and ZAP-70 expression, age, gender, Binet stage, β2-microglobulin levels, absolute lymphocyte count and number of lymph node regions.

Results

IGHV mutational status and 17p deletion were the sole biological variables with independent prognostic relevance in a multivariate model for overall survival, which included easily measurable clinical parameters (Binet staging, β2-microglobulin levels) and demographics (age and gender). Analysis of time to treatment in Binet A patients below 70 years of age showed that IGHV was the most important predictor. A novel 6-variable clinical-biological prognostic index was developed and internally validated, which assigned 3 points for Binet C stage, 2 points/each for Binet B stage and for age > 65 years, 1 point/each for male gender, high β2-microglobulin levels, presence of an unmutated IGHV gene status or 17p deletion. Patients were classified at low-risk (score = 0-1; 21%), intermediate-risk (score 2-5; 63% of cases), high-risk (score 6-9; 16% of cases). Projected 5-year overall survival was 98%, 90% and 58% in low-, intermediate- and high-risk groups, respectively. A nomogram for individual patient survival estimation was also proposed.

Conclusions

Data indicate that IGHV mutational status and 17p deletion may be integrated with clinical-demographic variables in new prognostic tools to estimate overall survival.

Concurrent search for unrelated cord and volunteer donor in high-risk acute lymphoblastic leukemia

To assess the effectiveness of the search for an unrelated donor on the outcome of patients with high-risk acute lymphoblastic leukemia, we analyzed prospectively 136 patients who underwent a search for cord blood (CB) and an unrelated volunteer donor (UD) at the same time. The probability of finding a donor was 58.2%, 70.3%, and 75.7% at 3, 6, and 12 months, respectively. The median time to find a donor was 1.8 months for CB and 3.5 months for UD. Of the 99 patients with a donor, 38.4% failed to undergo the transplant because of a relapse observed at a median of 4 months from the start of the search. In univariate analysis, absence of relapse during the search (p < 0.0001) and transplant (p = 0.004) showed a positive impact on long-term survival. In multivariate analysis, relapse during the search remained the key factor affecting survival (p < 0.0001). Since an extension of the search beyond 3 months enables only a slight increase in the probability of finding a donor compared to the increased risk of relapse, the time of the search should not exceed the 3-month time point. The simultaneous search for CB and UD increases the likelihood of performing a timely transplant.

Multiple myeloma shows no intra-disease clustering of immunoglobulin heavy chain genes

BACKGROUND

Characterization of the immunoglobulin gene repertoire has improved our understanding of the immunopathogenesis of lymphoid tumors. Early B-lymphocyte precursors of multiple myeloma are known to exist and might be susceptible to antigenic drive.

DESIGN AND METHODS

To verify this hypothesis, we collected a database of 345 fully readable multiple myeloma immunoglobulin sequences. We characterized the immunoglobulin repertoire, analyzed the somatic hypermutation load, and investigated for stereotyped receptor clusters.

RESULTS

Compared to the normal immunoglobulin repertoire, multiple myeloma displayed only modest differences involving only a few genes, showing that the myeloma immunoglobulin repertoire is the least skewed among mature B-cell tumors. Median somatic hypermutation load was 7.8%; median length of complementarity determining-region 3 was 15.5 amino acids. Clustering analysis showed the absence of myeloma specific clusters and no similarity with published chronic lymphocytic leukemia or lymphoma subsets.

CONCLUSIONS

Analysis of multiple myeloma immunoglobulin repertoire does not support a pathogenetic role for antigen selection in this tumor.

NOTCH1 mutations in +12 chronic lymphocytic leukemia (CLL) confer an unfavorable prognosis, induce a distinctive transcriptional profiling and refine the intermediate prognosis of +12 CLL

Trisomy 12, the third most frequent chromosomal aberration in chronic lymphocytic leukemia (CLL), confers an intermediate prognosis. In our cohort of 104 untreated patients carrying +12, NOTCH1 mutations occurred in 24% of cases and were associated to unmutated IGHV genes (P=0.003) and +12 as a sole cytogenetic abnormality (P=0.008). NOTCH1 mutations in +12 CLL associated with an approximately 2.4 fold increase in the risk of death, a significant shortening of survival (P<0.01) and proved to be an independent predictor of survival in multivariate analysis. Analogous to +12 CLL with TP53 disruption or del(11q), NOTCH1 mutations in +12 CLL conferred a significantly worse survival compared to that of +12 CLL with del(13q) or +12 only. The overrepresentation of cell cycle/proliferation related genes of +12 CLL with NOTCH1 mutations suggests the biological contribution of NOTCH1 mutations to determine a poor outcome. NOTCH1 mutations refine the intermediate prognosis of +12 CLL.

An Italian retrospective study on the routine clinical use of low-dose alemtuzumab in relapsed/refractory chronic lymphocytic leukaemia patients

Low-dose alemtuzumab has shown a favourable toxicity profile coupled with good results in terms of efficacy in relapsed/refractory chronic lymphocytic leukaemia (CLL). We conducted a multicentre retrospective study on the routine clinical use of low-dose alemtuzumab in this patient setting. One hundred and eight relapsed/refractory CLL patients from 11 Italian centres were included in the analysis. All patients had an Eastern Cooperative Oncology Group performance status ≤2 and the majority (84%) had adenopathies <5 cm. Low-dose alemtuzumab was defined as a total weekly dose ≤45 mg and a cumulative dose ≤600 mg given for up to 18 weeks. The overall response rate was 56% (22% complete remissions). After a median follow-up of 42.2 months, the median overall survival and progression-free survival were 39.0 and 19.4 months, respectively. In univariate analysis, response was inversely associated with lymph node (P = 0.01) and spleen (P = 0.02) size, fludarabine-refractoriness (P = 0.01) and del(11q) (P = 0.009). Advanced age and del(17p) were not associated with a worse outcome. Cumulative dose of alemtuzumab was not associated to response. Toxicities were usually mild and manageable; severe infections occurred in seven patients (7%) during therapy. This retrospective analysis confirms that low-dose alemtuzumab is a valid and currently used therapeutic option for the treatment of relapsed/refractory CLL.

The coexistence of chronic lymphocytic leukemia and myeloproliperative neoplasms: a retrospective multicentric GIMEMA experience

Although the coexistence of chronic lymphocytic leukemia (CLL) and myeloproliferative neoplasms (MPN) has been sporadically reported in the literature, no systematic studies on this disease association are available. We retrospectively analyzed 46 patients affected by CLL/MPN referred by 15 Italian GIMEMA centers. The aim of this retrospective multicenter study was to define the following: clinico-biological characteristics, possible familiarity, clinical course of both diseases, and influence of MPN chemotherapy on the course of CLL. Among 46 patients, 30 patients were males, 16 patients were females; median age was 71 years. Only one case had familiar CLL. Myeloproliferative disorders consisted of essential thrombocytemia in 18 cases, polycythemia vera in 10 cases, chronic myeloid leukemia in 9 cases, primary myelofibrosis in 6 cases, and MPN/myelodysplastic syndrome in 3 cases. The lymphoproliferative disorder was diagnosed as monoclonal B-cell lymphocytosis in 8 patients and as Binet Stage A CLL in 38 patients. After a median follow-up of 49 months, 9 patients experienced progressive CLL and only 6 patients required treatment after a median of 57.5 months. The biological profile confirmed a subset of low-risk CLL. Twenty patients received chemotherapy for MPN without influence on the course of CLL: lymphocyte counts remained unchanged after 3, 6, and 12 months of treatment. This series is the largest so far reported in literature. The diagnosis of concomitant CLL/MPN is a rare event and lymphoproliferative disorders present a clinical indolent course with a low-risk biological profile. MPN therapy does not interfere with the prognosis of patients with CLL.

CD73-generated extracellular adenosine in chronic lymphocytic leukemia creates local conditions counteracting drug-induced cell death

Extracellular adenosine (ADO), generated from ATP or ADP through the concerted action of the ectoenzymes CD39 and CD73, elicits autocrine and paracrine effects mediated by type 1 purinergic receptors. We have tested whether the expression of CD39 and CD73 by chronic lymphocytic leukemia (CLL) cells activates an adenosinergic axis affecting growth and survival. By immunohistochemistry, CD39 is widely expressed in CLL lymph nodes, whereas CD73 is restricted to proliferation centers. CD73 expression is highest on Ki-67(+) CLL cells, adjacent to T lymphocytes, and is further localized to perivascular areas. CD39(+)/CD73(+) CLL cells generate ADO from ADP in a time- and concentration-dependent manner. In peripheral blood, CD73 expression occurs in 97/299 (32%) CLL patients and pairs with CD38 and ZAP-70 expression. CD73-generated extracellular ADO activates type 1 purinergic A2A receptors that are constitutively expressed by CLL cells and that are further elevated in proliferating neoplastic cells. Activation of the ADO receptors increases cytoplasmic cAMP levels, inhibiting chemotaxis and limiting spontaneous drug-induced apoptosis of CLL cells. These data are consistent with the existence of an autocrine adenosinergic loop, and support engraftment of leukemic cells in growth-favorable niches, while simultaneously protecting from the action of chemotherapeutic agents.

New and old monoclonal antibodies for the treatment of chronic lymphocytic leukemia

Over the last few years, several new agents have been under evaluation in preclinical studies and clinical trials, showing promise in treating chronic lymphocytic leukemia (CLL). Among these agents, monoclonal antibodies (mAbs) such as rituximab and alemtuzumab have changed the natural course of the disease. Nowadays there are several new promising monoclonal antibodies under investigation against the CD20, CD23, CD37 and CD40 molecules. Application of newer monoclonal antibodies represents an area of ongoing clinical research in CLL.

CD38 in chronic lymphocytic leukemia: from bench to bedside?

Human CD38 is a cell surface molecule endowed with multiple functions. As an enzyme, it catalyzes the production of Ca2+ active metabolites, predominantly cADPR and ADPR. As a receptor, it regulates the activation of an intracellular signaling pathway, generally linked to lymphocyte activation and proliferation in physiological conditions. The finding that CD38 behaves as an independent negative prognostic factor in CLL patients was the starting point for investigations into the functional role of the molecule in the neoplastic context. Data accumulating in over a decade concur to define a model where CD38 is a central element of a large supramolecular complex that includes surface signaling receptors, chemokine receptors, adhesion molecules and matrix metalloproteases. Expression of CD38 within this supramolecular complex makes signal transduction as well as chemotaxis and homing more efficient, suggesting that the molecule is an integrator of proliferative and migratory signals. These data indicate that CD38 is not only a reliable disease marker but also a functional molecule in the CLL context. The next decade will likely tell whether it can also be a useful therapeutic target.

The role of MTHFR and RFC1 polymorphisms on toxicity and outcome of adult patients with hematological malignancies treated with high-dose methotrexate followed by leucovorin rescue

PURPOSE

In the last years, the influence of different genes involved in metabolism of chemotherapeutic agents has been studied. Methotrexate (MTX) is a key compound of chemotherapeutic regimens used in the treatment of acute lymphoblastic leukemia (ALL), primary central nervous system lymphoma (PCNSL) and Burkitt's lymphomas (BL). This study aims to evaluate the role of MTHFR C677T and A1298C polymorphisms and G80A reduced folate carrier gene (RFC1) in a cohort of adult patients with lymphoproliferative malignancies submitted to high-dose MTX followed by leucovorin rescue.

METHODS

We performed the analysis of these polymorphisms on genomic DNA with RFLP-PCR.

RESULTS

Patients carrying MTHFR A1298C variant showed decreased hepatic and hematological toxicity (P = 0.03). Overall survival (OS) and progression-free survival (PFS) between homozygous wild-type and variant patients for the RFC1 G(80)A were significantly different (P = 0.035 and P = 0.02, respectively). A significant correlation between hematological toxicity and age (P = 0.003) was observed. There was no significant influence of MTHFR C677T genotype on toxicity, OS and PFS.

CONCLUSIONS

Leucovorin rescue given after high-dose MTX probably accounts for the lack of influence of C677T polymorphism. To better define a role of RFC1 polymorphism on patients outcome, it would be worthwhile to perform a study on intracellular MTX level and RFC1 substrate binding affinities in different genotypes.

Circulating Regulatory T Cells in “Clinical” Monoclonal B-Cell Lymphocytosis

Regulatory T-cells (Tregs) constitute a small subset of cells involved in antitumour immunity and are generally increased in patients with chronic lymphocytic leukemia (CLL). No data is available on Tregs in monoclonal B-cell lymphocytosis (MBL), a disease entity characterized by less than 5000/μL circulating clonal B-cells in absence of other features of lymphoproliferative disorders. We used multicolour flow cytometry to evaluate the number of circulating Tregs in 56 patients with “clinical” MBL, 74 patients with previously untreated CLL and 40 healthy subjects. MBL patients showed a lower absolute number of Tregs, compared to CLL patients, but slightly higher than controls. Moreover, the absolute cell number of Tregs directly correlated both with more advanced Rai/Binet clinical stages and peripheral blood B-cell lymphocytosis. Of note, the absolute number of Tregs was found lower in MBL patients than in CLL patients staged as 0/A Rai/Binet. The study showed that Tregs increase gradually from normal subjects to “clinical” MBL patients and are significantly higher in CLL patients as compared to MBL patients. Moreover, a significant direct relationship was found between higher Treg values and a higher tumor burden expressed by B-lymphocytosis or more advanced clinical stages. In light of this data, MBL seems to be a preliminary phase preceding CLL. The progressive increase of Treg numbers might contribute both to the clinical evolution of MBL to overt CLL and to CLL progression.

Analysis of the chronic lymphocytic leukemia coding genome: role of NOTCH1 mutational activation

Next generation sequencing and copy number analysis provide insights into the complexity of the CLL coding genome, and reveal an association between NOTCH1 mutational activation and poor prognosis.

The pathogenesis of chronic lymphocytic leukemia (CLL), the most common leukemia in adults, is still largely unknown. The full spectrum of genetic lesions that are present in the CLL genome, and therefore the number and identity of dysregulated cellular pathways, have not been identified. By combining next-generation sequencing and copy number analysis, we show here that the typical CLL coding genome contains <20 clonally represented gene alterations/case, including predominantly nonsilent mutations, and fewer copy number aberrations. These analyses led to the discovery of several genes not previously known to be altered in CLL. Although most of these genes were affected at low frequency in an expanded CLL screening cohort, mutational activation of NOTCH1, observed in 8.3% of CLL at diagnosis, was detected at significantly higher frequency during disease progression toward Richter transformation (31.0%), as well as in chemorefractory CLL (20.8%). Consistent with the association of NOTCH1 mutations with clinically aggressive forms of the disease, NOTCH1 activation at CLL diagnosis emerged as an independent predictor of poor survival. These results provide initial data on the complexity of the CLL coding genome and identify a dysregulated pathway of diagnostic and therapeutic relevance.

Nicotinamide blocks proliferation and induces apoptosis of chronic lymphocytic leukemia cells through activation of the p53/miR-34a/SIRT1 tumor suppressor network

Because of its relatively indolent clinical course, chronic lymphocytic leukemia (CLL) offers a versatile model for testing novel therapeutic regimens and drug combinations. Nicotinamide is the main NAD(+) precursor and a direct inhibitor of four classes of enzymes, including the sirtuins. SIRT1, the main member of the sirtuin family, inactivates p53 by deacetylating a critical lysine residue. In this study, we showed that CLL cells express high levels of functional SIRT1, which is inhibited by exogenous nicotinamide. This agent blocks proliferation and promotes apoptosis selectively in leukemic cells that express wild-type (wt) p53. Nicotinamide modulates the p53-dependent genes p21, NOXA, BAX, and Mcl-1, indicating an activation of the p53 pathway and of caspase-3. DNA-damaging chemotherapeutics, such as etoposide, activate a functional loop linking SIRT1 and p53 through the induction of miR-34a. When leukemic cells are simultaneously exposed to nicotinamide and etoposide, we observe a significant increase in miR-34a levels with a concomitant inhibition of SIRT1. Furthermore, p53 acetylation levels are higher than with either agent used alone. Overall, treatment with both nicotinamde and etoposide shows strongly synergistic effects in the induction of apoptosis. We therefore concluded that nicotinamide has the dual property of inhibiting SIRT1 through a noncompetitive enzymatic block (p53 independent) and at the same time through miR-34a induction (p53 dependent). These observations suggested the therapeutic potential of nicotinamide, a novel, safe, and inexpensive drug, to be used in addition to chemotherapy for CLL patients with wt p53.

13q14 deletion size and number of deleted cells both influence prognosis in chronic lymphocytic leukemia

Deletion at 13q14 is detected by fluorescence in situ hybridization (FISH) in about 50% of chronic lymphocytic leukemia (CLL). Although CLL with 13q deletion as the sole cytogenetic abnormality (del13q-only) usually have good prognosis, more aggressive clinical courses are documented for del13q-only CLL carrying higher percentages of 13q deleted nuclei. Moreover, deletion at 13q of different sizes have been described, whose prognostic significance is still unknown. In a multi-institutional cohort of 342 del13q-only cases and in a consecutive unselected cohort of 265 CLL, we investigated the prognostic significance of 13q deletion, using the 13q FISH probes locus-specific identifier (LSI)-D13S319 and LSI-RB1 that detect the DLEU2/MIR15A/MIR16-1 and RB1 loci, respectively. Results indicated that both percentage of deleted nuclei and presence of larger deletions involving the RB1 locus cooperated to refine the prognosis of del13q-only cases. In particular, CLL carrying <70% of 13q deleted nuclei with deletions not comprising the RB1 locus were characterized by particularly long time-to-treatment. Conversely, CLL with 13q deletion in <70% of nuclei but involving the RB1 locus, or CLL carrying 13q deletion in ≥70% of nuclei, with or without RB1 deletions, collectively experienced shorter time-to-treatment. A revised flowchart for the prognostic FISH assessment of del13q-only CLL, implying the usage of both 13q probes, is proposed.

Abstract 389: CD38 is part of a network of molecules regulating chemotaxis and homing of CLL cells

An essential step in the maintenance and progression of chronic lymphocytic leukemia (CLL) is the recirculation of leukemic cells from blood to favorable growth niches in the lymphoid organs. This process is regulated by an intricate network of signals, including chemokines and their receptors, adhesion molecules and proteases that digest the extracellular matrix. The CXCL12/CXCR4 axis is believed to play an essential role in the regulation of the homing process, re-directing CLL cells to BM and LN. The CD49d integrin mediates adhesion to other cells or to the extracellular matrix via VCAM-1 or CS-1 fibronectin fragment. Lastly, the extra-vasation step is mainly controlled by MMP-9, the only gelatinases expressed by CLL cells. The working hypothesis is that CD38 may be involved in these three aspects of leukocyte homing, through a physical and functional association with CXCR4, CD49d and MMP-9. CLL cells from a molecularly and clinically characterized cohort of patients were used. Functional responses to CXCL12 were studied by immunoblot and chemotaxis. Genetic manipulation of CLL cells was carried out using a lentiviral techinique. The activity of MMP-9 in CLL cells was analyzed by gelatin zymography. Results indicate that CD38 expression marks i) CLL cells that are highly sensitive to the actions of the CXCL12. Furthermore, ii) CD38+ cases are characterized by a higher expression and activity of MMP-9. Moreover, iii) the analysis of CLL patients with a bimodal expression of CD38 indicates that the CD38+ fraction of the clone is characterized by higher levels of MMP-9 compared to the negative one. These data suggest that the CD38+ component of a CLL clone is enriched in cells that have the molecular machinery to migrate from the blood to the lymphoid organs. A formal proof of the role played by CD38 was obtained using a lentiviral technique that allows genetic modification of freshly purified CLL cells. De novo expression of CD38 was followed by an increased sensitivity to the CXCL12 chemokine as well as by secretion of high amounts of the active form of MMP-9, suggesting that de novo CD38+ cells digest extracellular matrix more readily compared to the same cells infected with an empty virus. Finally, the engagement of CD38 by means of agonistic mAbs was followed by increased chemotaxis and MMP-9 activation, while blocking anti-CD38 mAbs were highly effective in preventing CLL homing in an in vivo mouse model. Finally, v) CD38 appears to co-localize with CXCR4 and MMP-9 in the same membrane areas, as inferred by confocal microscopy analysis. These results suggest that CD38 is part of a complex network of molecules/signals that fine tune homing of leukemic cells to growth-permissive microenvironment. The physical proximity of these molecules on CLL membrane indicate that they could form a large supramolecular complex with the characteristic of the invadosome, linking the ability to migrate and invade to the poor clinical outcome of these patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 389. doi:10.1158/1538-7445.AM2011-389

Abstract 2630: Nicotinamide activates the p53/miR-34a/SIRT1 tumor suppressor network leading to apoptosis of chronic lymphocytic leukemia cells

Nicotinamide, the amide form of the B-complex vitamin niacin, is the main precursor of NAD+ in most mammalian cells. Tumor transformation is generally accompanied by profound alterations in total cellular NAD+ and nicotinamide levels, and consequently in the activities of NAD+-dependent enzymes. Among these enzymes, sirtuins are class III histone deacetylases. SIRT1, the best characterized member, plays important roles in gene silencing, aging and longevity deacetylating histone and non-histone proteins, including p53. Several evidences indicate that SIRT1 may work as an oncogene by suppressing p53 functions, leading to genome instability and resistance to apoptosis. For these reasons, there is intense investigation in designing molecular tools that inhibit sirtuins.

Because of a longstanding experience in the use of nicotinamide for the treatment of pellagra and because of the lack of reported side effects, nicotinamide could be in the pipeline of SIRT1 inhibitors to be tested in clinical settings. Our hypothesis is that nicotinamide affects human B cell homeostasis and that the effects might be more marked in a neoplastic context. Chronic lymphocytic leukemia (CLL), selected as disease model, is characterized by the slowly progressive expansion of a population of mature monoclonal B lymphocytes, intrinsically resistant to apoptosis.

The results of this study confirm that CLL cells are characterized by increased expression and function of SIRT1, compared to normal B lymphocytes from peripheral blood of age- and sex-matched donors. Nicotinamide treatment directly leads to enzymatic activity inhibition of SIRT1 evident only in leukemic cells. Functional block of this enzyme is followed by re-activation of the p53 pathway marked by increased expression of p53-dependent genes, such as p21, NOXA and BAX and decreased of Mcl-1. The endpoint is a block of the cell cycle and induction of apoptosis in CLL cells with a wild type p53. Conversely CLL cells with a mutated/deleted p53 protein are partially resistant to nicotinamide-mediated effects.

Our hypothesis is that the link between SIRT1 and p53 is represented by miR-34a, a direct transcriptional target of p53 that can bind SIRT1 mRNA and trigger its degradation. In line with this hypothesis, a combined treatment of CLL cells with nicotinamide and etoposide (a DNA-damaging chemotherapeutic) is followed by i) up-regulation of miR-34a expression, ii) marked down-modulation of SIRT1 expression and function, and iii) induction of expression and acetylation of p53. This positive feedback loop is operative in the CLL model, with the final outcome of a tumor cell apoptosis significantly enhanced.

In conclusion this work suggests that nicotinamide represents a potentially useful adjunct in the treatment of selected forms of CLL, also considering that normal B lymphocytes are markedly less sensitive to nicotinamide effects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2630. doi:10.1158/1538-7445.AM2011-2630

Intralesional administration of rituximab for treatment of CD20 positive orbital lymphoma: safety and efficacy evaluation

B-cell lymphomas constitute the most frequent malignant neoplasm of the ocular adnexal, often presenting with localized disease. Five patients with primary localized CD20 positive B cell non Hodgkin ocular adnexal lymphomas received intralesional rituximab at the dose of 5mg once a week for one month, followed by 10mg weekly in case of incomplete response. Four of five patients obtained regression of symptoms and 2 of them showed complete response. No patients experienced side effects besides pain on the site of the injection. Local treatment with Rituximab for OAL is a safe and useful first-line therapeutic option.

B-cell receptor, clinical course and prognosis in chronic lymphocytic leukaemia: the growing saga of the IGHV3 subgroup gene usage

The immunoglobulin heavy chain variable gene (IGHV) mutational status has been recognized as an important predictor of prognosis in chronic lymphocytic leukaemia (CLL) since 1999. More recently, other features of the B-cell receptor, such as stereotypy, have been identified as capable of refining the prognostic potential of IGHV status in the clinical assessment of CLL patients. In this context, different genes belonging to the IGHV3 subgroup, the most frequently used subgroup in CLL, have been shown to denote disease subsets that either display a bad prognosis (i.e. IGHV3-21, IGHV3-23) or are associated with particularly good clinical outcomes, including a highly stable/indolent clinical course, even prone to spontaneous regression (i.e. IGHV3-72, IGHV3-30). The present review focuses on the molecular and biological features of CLL-expressing specific genes belonging to the IGHV3 subgroup that are known to mark disease subsets with completely different clinical courses, and may be possibly related to CLL pathogenesis via antigen and/or superantigen involvement.

Mycosis fungoides as a cause of severe obstructive sleep apnea

We report the case of a 38-year-old woman, affected by a cutaneous form of mycosis fungoides (MF) who presented with a history of loud snoring associated with sleep apnea. A polysomnographic study confirmed the presence of severe obstructive sleep apnea syndrome (OSAS). Cranial and neck MRI revealed a neoplastic infiltration of the tongue base and the posterior pharynx wall. Upper airway neoplastic infiltration is rarely reported as a cause of OSAS and extra-cutaneous localizations of MF are uncommon. This is the first case in the literature of a patient with nocturnal polysomnogram documented OSAS caused by a mucosal involvement of MF.

A variant of the LRP4 gene affects the risk of chronic lymphocytic leukaemia transformation to Richter syndrome

Richter syndrome (RS) represents the transformation of chronic lymphocytic leukaemia (CLL) to aggressive lymphoma. Risk factors of CLL transformation to RS are only partly known. We explored the role of the host genetic background as a risk factor for RS occurrence. Forty-five single nucleotide polimorphisms (SNPs) known to be relevant for CLL prognosis were genotyped in a consecutive cohort of 331 CLL, of which 21 had transformed to RS. After correcting for multiple testing and adjusting for previously reported RS risk factors, the LRP4 rs2306029 TT variant genotype was the sole SNP independently associated with a higher risk of RS transformation (Hazard Ratio: 4·17; P = 0·001; q = 0·047). The enrichment of LRP4 TT genotype in RS was confirmed in an independent series (n = 44) used for validation purposes. The LRP4 protein was expressed in CLL (n =66). Bioinformatic analysis scored LRP4 rs2306029 as a variant with possible deleterious and damaging variant of LRP4. LRP4 genotyping may help the recognition of patients with increased risk of RS at the time of CLL diagnosis.

Regulatory T-cell number is increased in chronic lymphocytic leukemia patients and correlates with progressive disease

Regulatory T-cells (Treg) actively maintain immunological self-tolerance and play a significant role in the progression of cancer. Treg cell numbers have been evaluated in 80 patients with previously untreated chronic lymphocytic leukemia (CLL) and in 40 normal healthy volunteers. Treg cells are higher in CLL patients than in controls and correlate with disease status (more advanced clinical stage, peripheral blood B-cell lymphocytosis, absolute CD38+ B-cell number, and more elevated LDH levels). No correlation was found with ZAP-70 expression, IgVH mutational status and cytogenetic abnormalities. This data shows that Treg cell number is abnormal in CLL patients.

Reduced expression of the tumor suppressor PHLPP1 enhances the antiapoptotic B-cell receptor signal in chronic lymphocytic leukemia B-cells

The PI3K/Akt pathway is activated in response to various microenvironmental stimuli that regulate the survival and proliferation of chronic lymphocytic leukemia (CLL) B-cells, including triggering of the B-cell receptor (BCR). Although this pathway is frequently targeted in cancer, no significant alterations have yet been identified in CLL. We now show that the phosphatase PH domain leucin-rich repeat protein phosphatase (PHLPP1), a recently identified tumor suppressor and negative regulator of the Akt kinase, is absent or expressed at substantially reduced levels in CLL B-cells. To determine what the consequences of PHLPP1 loss on BCR signaling are, we downregulated or re-expressed PHLPP1 in lymphoma cell lines and primary CLL B-cells, respectively. Downregulation of PHLPP1 increased BCR-induced phosphorylation and activation of the Akt, GSK3 and ERK kinases, whereas re-expression had the opposite effect. Importantly, re-expression of PHLPP1 in primary CLL cells prevented upregulation of Mcl-1 and inhibited the increase in leukemic cell viability induced by sustained BCR engagement. Enforced expression of PHLPP1 also affected the response to other microenvironmental stimuli, particularly in terms of ERK phosphorylation. Collectively, these data show that CLL cells lack an important negative regulator of the Akt and ERK pathways, which could confer them a growth advantage by facilitating the propagation of crucial microenvironment-derived stimuli.

Multicentre validation of a prognostic index for overall survival in chronic lymphocytic leukaemia

We wish to validate in a multicentric CLL population a nomogram and a risk score recently developed to predict overall survival (OS). Complete records from 1037 CLL patients were retrospectively collected to estimate OS and time to treatment (TTT). Cox models were used to test the independence of age, β-2-microglobulin, absolute lymphocyte count (ALC), sex, Rai stage and number of involved lymph node regions (LNR). Accuracy of prognostic models was tested with the concordance index (c-index). Median follow-up was 5.5 years, with 151 deaths and 475 treated patients. Median OS was not reached (65% survival rate at 13.9 years), median TTT was 6 years. We confirmed the ability of the prognostic score to predict OS and TTT in three risk groups, with results comparable with those reported in the original report. However, ALC and Rai stage were not independent predictors, whereas the Binet staging system, which incorporates LNR variable, showed independent predictive power; furthermore, both 5- and 10-year OS estimates from nomogram were lower compared to real data. When separately analysed, the impact of therapy on OS was not selected as independent predictor of OS in our series. According to these results, we proposed a simpler four-variable model (age, sex, Binet staging, β-2-microglobulin) and a new nomogram. This model had a c-index of 0.78 versus 0.76 of the six-variable model (p  =  0.043), showing better predictive accuracy. External validation and refinement are needed on independent data sets, possibly from cancer registry patients' series.