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 use of monoclonal antibodies in the treatment of autoimmune complications of chronic lymphocytic leukemia

Autoimmune cytopenias are a frequent complication in CLL, occurring in approximately 5-10% of the patients. The most common manifestation is autoimmune haemolytic anaemia, followed by immune thrombocytopenia and only rarely pure red blood cell aplasia or autoimmune granulocytopenia. Initial treatment is as for the idiopathic autoimmune cytopenias, with most patients responding to conventional corticosteroid therapy. Patients, who do not respond to conventional therapy after 4-6 weeks, should be considered for alternative immunosuppression, monoclonal antibody therapy or splenectomy. While randomized trials demonstrating the benefit of rituximab in CLL-related autoimmune diseases are still lacking, there are considerable data in the literature that provide evidence for its effectiveness. The monoclonal antibody alemtuzumab also displays considerable activity against both the malignant disease and the autoimmune complication in patients with CLL, although at the expense of greater toxicity. A number of new monoclonal antibodies, such as ofatumumab, GA-101, lumiliximab, TRU-016, epratuzumab, and galiximab, are currently investigated in CLL and their activity in CLL-related autoimmune cytopenias should be evaluated in future studies.

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.

Mutations of NOTCH1 are an independent predictor of survival in chronic lymphocytic leukemia

Analysis of the chronic lymphocytic leukemia (CLL) coding genome has recently disclosed that the NOTCH1 proto-oncogene is recurrently mutated at CLL presentation. Here, we assessed the prognostic role of NOTCH1 mutations in CLL. Two series of newly diagnosed CLL were used as training (n = 309) and validation (n = 230) cohorts. NOTCH1 mutations occurred in 11.0% and 11.3% CLL of the training and validation series, respectively. In the training series, NOTCH1 mutations led to a 3.77-fold increase in the hazard of death and to shorter overall survival (OS; P < .001). Multivariate analysis selected NOTCH1 mutations as an independent predictor of OS after controlling for confounding clinical and biologic variables. The independent prognostic value of NOTCH1 mutations was externally confirmed in the validation series. The poor prognosis conferred by NOTCH1 mutations was attributable, at least in part, to shorter treatment-free survival and higher risk of Richter transformation. Although NOTCH1 mutated patients were devoid of TP53 disruption in more than 90% cases in both training and validation series, the OS predicted by NOTCH1 mutations was similar to that of TP53 mutated/deleted CLL. NOTCH1 mutations are an independent predictor of CLL OS, tend to be mutually exclusive with TP53 abnormalities, and identify cases with a dismal prognosis.

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.