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J Liu,
G Chen,
L Feng,
W Zhang,
H Pelicano,
F Wang,
M A Ogasawara,
W Lu,
H M Amin,
C M Croce, M J Keating,
P Huang
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ABSTRACT: Chronic lymphocytic leukemia (CLL) patients with deletion of chromosome 17p, where the p53 gene is located, often develop more aggressive disease with poor clinical outcomes. To investigate the underlying mechanisms for the highly malignant phenotype of 17p- CLL and to facilitate in vivo evaluation of potential drugs against CLL with p53 deletion, we have generated a mouse model with TCL1-Tg:p53(-/-) genotype. These mice develop B-cell leukemia at the early age with an early appearance of CD5(+)/IgM(+) B cells in the peritoneal cavity and spleen, and exhibit aggressive path of disease development and drug resistance phenotype similar to human CLL with 17p deletion. The TCL1-Tg:p53(-/-) leukemia cells exhibit higher survival capacity and are more drug-resistant than the leukemia cells from TCL1-Tg:p53wt mice. Analysis of microRNA expression reveals that p53 deletion resulted in a decrease of miR-15a and miR-16-1, leading to an elevated expression of Mcl-1. Primary leukemia cells from CLL patients with 17p deletion also show a decrease in miR-15a/miR-16-1 and an increase in Mcl-1. Our study suggests that the p53/miR15a/16-1/Mcl-1 axis may be an important pathway that regulates Mcl-1 expression and contributes to drug resistance and aggressive phenotype in CLL cells with loss of p53.Leukemia accepted article preview online, 23 April 2013; doi:10.1038/leu.2013.125.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 04/2013; · 8.30 Impact Factor
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ABSTRACT: The tissue microenvironment in chronic lymphocytic leukemia (CLL) has an increasingly recognized role in disease progression, but the molecular mechanisms of cross talk between CLL cells and their microenvironment remain incompletely defined. Bone marrow stromal cells (BMSC) protect CLL cells from apoptosis in a contact-dependent fashion, and have been used for the identification of key pathways such as the CXCR4-CXCL12 axis. To further dissect the molecular impact of BMSC on survival and the molecular activation signature of CLL cells, we co-cultured CLL cells with different BMSC. Gene expression profiling of CLL cells revealed that the lymphoid proto-oncogene TCL1 was among the top genes upregulated in CLL cells by BMSC. TCL1 mRNA and protein upregulation by BMSC was paralleled by decreases of TCL1-interacting FOS/JUN, and confirmed by qRT-PCR, immunoblotting, immunoprecipitations, and flow cytometry. Stroma mediated increases in TCL1 were also associated with decreased levels of TCL1-regulatory micro-RNAs (miR-29b, miR-181b, miR-34b). These findings demonstrate that the microenvironment has a proactive role in the regulation of the known signaling enhancer and pro-survival molecule TCL1 in CLL. This provides a further rationale for therapeutically targeting the cross talk between CLL and BMSC.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 03/2012; 26(8):1812-20. · 8.30 Impact Factor
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J Hoellenriegel,
G P Coffey,
U Sinha,
A Pandey,
M Sivina,
A Ferrajoli,
F Ravandi,
W G Wierda,
S O'Brien, M J Keating,
J A Burger
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ABSTRACT: Syk is a protein tyrosine kinase that couples B-cell receptor (BCR) activation with downstream signaling pathways, affecting cell survival and proliferation. Moreover, Syk is involved in BCR-independent functions, such as B-cell migration and adhesion. In chronic lymphocytic leukemia (CLL), Syk becomes activated by external signals from the tissue microenvironment, and was targeted in a first clinical trial with R788 (fostamatinib), a relatively nonspecific Syk inhibitor. Here, we characterize the activity of two novel, highly selective Syk inhibitors, PRT318 and P505-15, in assays that model CLL interactions with the microenvironment. PRT318 and P505-15 effectively antagonize CLL cell survival after BCR triggering and in nurse-like cell-co-cultures. Moreover, they inhibit BCR-dependent secretion of the chemokines CCL3 and CCL4 by CLL cells, and leukemia cell migration toward the tissue homing chemokines CXCL12, CXCL13, and beneath stromal cells. PRT318 and P505-15 furthermore inhibit Syk and extracellular signal-regulated kinase phosphorylation after BCR triggering. These findings demonstrate that the selective Syk inhibitors PRT318 and P505-15 are highly effective for inhibition of CLL survival and tissue homing circuits, and support the therapeutic development of these agents in patients with CLL, other B-cell malignancies and autoimmune disorders.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 02/2012; 26(7):1576-83. · 8.30 Impact Factor
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Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 03/2010; 24(5):1096-8. · 8.30 Impact Factor
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ABSTRACT: Fludarabine Monophosphate (FLU) is an adenosine analogue with a high-level of anti-leukemic activity in patients (pts) with CLL. FLU (25–30 mg/m2/day × 5 every 4 weeks) was given to 78 previously treated pts with CLL. The overall response rate was 58% (CR 11%, nodular CR 26%, PR 21%). Subsequently, prednisone (P, 30 mg/m2/day × 5) was added to the FLU regimen and administered to 169 pts. The response rate, up to this time, was similar to the FLU regimen 52% (CR 12%, nodular CR 28%, PR 12%). The major toxicity was febrile episodes which occurred in one course in 5 for both groups of pts. The median survival was also similar in both groups (FLU 74 weeks and FLU + P 103 weeks). Thus, no advantage was noted with the addition of P to FLU. FLU and FLU + P have been administered to 36 pts and 62 pts respectively who have had no prior treatment. The response rate for FLU was 83% (CR 39%, nodular CR 36%, PR 8%) and FLU + P was 82% (CR 29%, nodular CR 34%, PR 19%). Several of the FLU + P group developed persistent thrombocytopenia despite a good anti-leukemic response. The rates of decrease of the circulating and marrow lymphocyte counts were similar for the FLU and FLU + P groups. No survival difference has been noted to date in these groups. Time to development of progressive disease in the previously treated pts FLU and FLU + P is 104 weeks and is similar for the CR and nodular CR pts 118 weeks vs. 97 weeks and for the PR pts 89 weeks. All pts appear eventually to recur. Insufficient data is available to evaluate the time to progression of the previously treated pts. Two parameter flow-cytometry for CD19 and CD5, Kappa/Lamda ratio and immunoglobulin gene rearrangement studies are able to detect residual bone marrow disease in a majority of pts with CR and nodular CR (BM lymphocytes <30%). As relapse appears to be inevitable in the previously treated group who respond, post-remission therapy will include autologous bone marrow transplantation for pts <60 years of age and recombinant alpha-Interferon for pts >60 years of age. Post-remission therapy for the previously untreated responders will not be given to allow an estimate of the unmaintained time to progression. Bone marrow will be stored in first remission for future use, if the pts recur. Combination therapy studies utilizing FLU combined with Ara-C or Doxorubicin are being conducted.
06/2009; 5(s1):139-142.
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ABSTRACT: Mutation of Bcr-Abl is an important mechanism by which chronic myelogenous leukemia (CML) cells become resistant to Gleevec. The T315I mutation is clinically significant since CML cells harboring this mutation are insensitive to Gleevec and other Bcr-Abl-targeted drugs. Identification of new agents capable of effectively killing CML cells with T315I mutation would have important therapeutic implications in Gleevec-resistant CML. Here, we showed that beta-phenylethyl isothiocyanate (PEITC), a natural compound found in vegetables, is effective in killing CML cells expressing T315I BCR-ABL. Treatment of leukemia cell lines harboring wild-type or mutant Bcr-Abl with 10 microM PEITC resulted in an elevated ROS stress and a redox-mediated degradation of the BCR-ABL protein, leading to massive death of the leukemia cells. Antioxidant NAC attenuated the PEITC-induced oxidative stress in CML cells and prevented the degradation of BCR-ABL, caspase-3 activation and cell death. We further showed that the ROS-induced degradation of BCR-ABL was mediated partially by caspase-3 and the proteasome pathway. The ability of PEITC to effectively kill T315I-positive CML cells was further confirmed using primary leukemia cells isolated from CML patients. Our results suggest that PEITC is a promising compound capable of killing Gleevec-resistant CML cells through a ROS-mediated mechanism and warrants further investigations.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 07/2008; 22(6):1191-9. · 8.30 Impact Factor
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Value in Health 01/2008; 11(6). · 2.19 Impact Factor
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A Safdar,
G Rodriguez,
K V I Rolston,
S O'Brien,
I F Khouri,
E J Shpall, M J Keating,
H M Kantarjian,
R E Champlin,
I I Raad,
D P Kontoyiannis
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ABSTRACT: Pneumocandins have concentration-dependent antifungal activity and higher dose of caspofungin (HD-CAP) in combination with other licensed antifungal therapy (OLAT) may improve response. Thirty-four patients who received HD-CAP were compared with 63 patients who received standard dose (SD)-CAP. There were no differences between the groups in either patient or disease characteristics. Significantly more patients in the HD-CAP arm had extrapulmonary infections (29 vs 8% in SD group; P=0.0053), and non-Aspergillus species infection (21 vs 6%; P=0.05) and had received prior antifungal therapy (71 vs 33%; P=0.0004). No serious adverse reactions were noted in patients receiving HD- or SD-CAP therapy. Twelve weeks after treatment commenced 44% had a complete or partial response compared with 29% in SD-CAP group (P=0.1). Logistic regression analysis showed a significant probability of a favorable outcome at 12 weeks in patients who received HD-CAP (OR 3.066, 95% CI, 1.092-8.61; P=0.033). This may in part reflect higher number of patients in HD group had received granulocyte-macrophage colony-stimulating factor (41 vs 14% in SD group; P=0.04) and/or interferon gamma (26 vs 5% in SD group; P=0.003) immune enhancement. Further studies are needed to evaluate efficacy of HD-CAP in severely immunosuppressed cancer patients with invasive fungal infections.
Bone Marrow Transplantation 03/2007; 39(3):157-64. · 3.75 Impact Factor
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Leukemia 09/2006; 20(8):1452-3. · 9.56 Impact Factor
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ABSTRACT: 17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a new anticancer agent currently in clinical trials. The ability of 17-AAG to abrogate the function of heat-shock protein Hsp90 and modulate cellular sensitivity to anticancer agents has prompted recent research to use this compound in drug combination therapy. Here we report that 17-AAG has striking opposite effects on the activity of arsenic trioxide (ATO) and ara-C. Combination of 17-AAG with ATO exhibited a synergistic effect in leukemia cells, whereas coincubation of 17-AAG and ara-C showed antagonistic activity. Mechanistic studies revealed that ATO exerted cytotoxic action by reactive oxygen species generation, and activated Akt survival pathway. 17-AAG abrogated Akt activation and enhanced the activity of ATO. In contrast, treatment of leukemia cells with 17-AAG caused a G1 arrest, a decrease in DNA synthesis and reduced ara-C incorporation into DNA, leading to antagonism. The ability of 17-AAG to enhance the antileukemia activity of ATO was further demonstrated in primary leukemia cells isolated from patients with acute myeloid leukemia and chronic lymphocytic leukemia, including cells from refractory patients. Our data suggest that combination of 17-AAG and ATO may be an effective therapeutic regimen. Caution should be exercised in using 17-AAG together with ara-C, as their combination effects are schedule dependent.
Leukemia 05/2006; 20(4):610-9. · 9.56 Impact Factor
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ABSTRACT: The mammalian target of rapamycin (mTOR) pathway plays important roles in regulating nutrient metabolism and promoting the growth and survival of cancer cells, which exhibit increased glycolysis for ATP generation. In this study, we tested the hypothesis that inhibition of the mTOR pathway and glycolysis would synergistically impact the energy metabolism in cancer cells and may serve as an effective therapeutic strategy to kill malignant cells. Using human lymphoma cells and leukemia cells, we demonstrated that the combination of rapamycin, an mTOR inhibitor, with a glycolytic inhibitor produced synergistic cytotoxic effect, as evidenced by apoptosis and cell growth inhibition assays. Mechanistic studies showed that inhibition of the mTOR pathway by rapamycin alone sufficiently suppressed the phosphorylation of the downstream molecules p70S6K and 4E-BP-1, but only caused a moderate cytostatic effect. Combination of mTOR inhibition and blockage of glycolysis synergistically suppressed glucose uptake and severely depleted cellular ATP pools, leading to significant enhancement of cell killing. In contrast, combination of rapamycin and ara-C did not increase cytotoxicity in vitro. Our findings suggest that targeting mTOR pathway in combination with inhibition of glycolysis may be an effective therapeutic strategy for hematological malignancies. This mechanism-based drug combination warrants further investigation in preclinical and clinical settings.
Leukemia 01/2006; 19(12):2153-8. · 9.56 Impact Factor
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ABSTRACT: Patients with chronic lymphocytic leukemia (CLL) have defects in both cellular and humoral immunity. Since CD152 (CTLA-4) plays a critical role in downregulating T-cell responses, we studied the expression of surface and cytoplasmic CD152 (sCD152 and cCD152, respectively) in freshly isolated T cells from treatment-naïve patients with CLL. CD4+ and CD8+ T cells from these patients demonstrated significantly increased sCD152 and cCD152 compared to normal donors. Furthermore, these patients had an increased proportion of the regulatory CD4(+)/CD25(+)/CD152+ subset that correlated with advanced Rai stage, unfavorable cytogenetics and low serum IgG and IgA levels. The expression of sCD152 by T cells also correlated with ZAP-70 expression by CLL B cells. The proportion of CD4(+)/CD25+ cells was also correlated with unmutated immunoglobulin heavy chain variable gene status. Blockade of CD152 with monoclonal antibody (mAb) in proliferation assays was associated with potent T-cell proliferation in response to autologous and allogeneic CD40-activated CLL B cells. In summary, T cells from patients with CLL may be primed for anergy by expressing increased amounts of CD152; anti-CD152 mAb may represent a therapeutic opportunity to enhance an immune response against autologous leukemia cells.
Leukemia 11/2005; 19(10):1788-93. · 9.56 Impact Factor
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J Kurtzberg,
T J Ernst, M J Keating,
V Gandhi,
J P Hodge,
D F Kisor,
J J Lager,
C Stephens,
J Levin,
T Krenitsky,
G Elion,
B S Mitchell
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ABSTRACT: A phase I study was conducted to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetics of a novel purine nucleoside, nelarabine, a soluble prodrug of 9-beta-D-arabinosylguanine (araG; Nelarabine), in pediatric and adult patients with refractory hematologic malignancies.
Between April 1994 and April 1997, 93 patients with refractory hematologic malignancies were treated with one to 16 cycles of study drug. Nelarabine was administered daily, as a 1-hour intravenous infusion for 5 consecutive days, every 21 to 28 days. First-cycle pharmacokinetic data, including plasma nelarabine and araG levels, were obtained on all patients treated. Intracellular phosphorylation of araG was studied in samples of leukemic blasts from selected patients.
The MTDs were defined at 60 mg/kg/dose and 40 mg/kg/dose daily x 5 days in children and adults, respectively. Dose-limiting toxicity (DLT) was neurologic in both children and adults. Myelosuppression and other significant organ toxicities did not occur. Pharmacokinetic parameters were similar in children and adults. Accumulation of araGTP in leukemic blasts was correlated with cytotoxic activity. The overall response rate was 31%. Major responses were seen in patients with T-cell malignancies, with 54% of patients with T-lineage acute lymphoblastic leukemia achieving a complete or partial response after one to two courses of drug.
Nelarabine is a novel nucleoside with significant cytotoxic activity against malignant T cells. DLT is neurologic. Phase II and III trials in patients with T-cell malignancies are encouraged.
Journal of Clinical Oncology 06/2005; 23(15):3396-403. · 18.37 Impact Factor
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ABSTRACT: B cell chronic lymphocytic leukemia (CLL) is the most prevalent adult leukemia in the Western hemisphere, yet many biological and molecular features of the disease remain undefined. CLL cells generate increased levels of radical species such as superoxide and nitric oxide (NO), which is associated with mitochondrial DNA mutations. Considering that NO levels can affect mitochondrial biogenesis, we hypothesized that the inherent nitrosative stress in CLL cells may lead to hyperactive mitochondrial biogenesis. Here we report that primary CLL cells contained significantly more mitochondria than normal lymphocytes and that their mitochondrial mass was significantly related to endogenous NO levels. Expression of the mitochondrial biogenesis factors nuclear respiratory factor-1 and mitochondrial transcription factor A was elevated in most CLL specimens examined and appeared to be related to cellular NO levels. Treatment of B cells with exogenous NO caused a substantial increase in mitochondrial mass. In vitro sensitivity of CLL cells to fludarabine was highly related to mitochondrial mass in that cells with greater mitochondrial mass were less sensitive to the drug. Taken together, our results suggest that NO is a key mediator of mitochondrial biogenesis in CLL and that modulation of mitochondrial biogenesis by NO may alter cellular sensitivity to fludarabine.
Leukemia 01/2005; 18(12):1934-40. · 9.56 Impact Factor
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Leukemia 12/2004; 18(11):1912-4. · 9.56 Impact Factor
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ABSTRACT: Novel therapeutic approaches with conventional chemotherapy and monoclonal antibody combinations have improved the complete remission rates in chronic lymphocytic leukemia. However, cure remains elusive, particularly in fludarabine-refractory patients, whose prognosis remains poor. Autologous stem cell transplantation (SCT) has been explored for such patients, lengthening the time to treatment failure in selected patients, but there is little hope that it will improve the cure rate. The strategy is particularly ineffective in patients with poor biological prognostic factors, such as abnormal cytogenetics and unmutated immunoglobulin heavy-chain variable region. Allogeneic SCT remains the only curative approach, producing an extended disease-free survival in 25-60%, mainly via the graft-versus-leukemia effect. The treatment-related mortality with such an approach has been significant, however, with a 30-40% risk of death within 100 days of the transplant. Nonmyeloablative (NMA) conditioning regimens may produce high response rates and lower morbidity, especially for patients with chemosensitive disease. Randomized trials designed according to the new biologic prognostic parameters described in chronic lymphocytic leukemia are required to better define the role of NMA SCT in the near future.
Bone Marrow Transplantation 09/2004; 34(4):289-97. · 3.75 Impact Factor
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ABSTRACT: Alemtuzumab is effective in reducing the risk of acute graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (ASCT). Alemtuzumab may also delay immune reconstitution and reduce graft-versus-leukemia effects. The optimal dose has not been established. We investigated engraftment, acute GVHD incidence and severity, and pharmacokinetics of alemtuzumab associated with the use of low-dose alemtuzumab/cyclophosphamide/total body irradiation and ASCT for patients with aggressive CD52-positive hematologic malignancies. In all, 12 patients were treated. Alemtuzumab 10 mg daily on days -7 to -3 was given intravenously. Tacrolimus and methotrexate were used for GVHD prophylaxis. Alemtuzemab was not detected in any of the 36 sequential serum samples tested between days -1 and +21 of transplant. All patients engrafted rapidly; the median time to an absolute neutrophil count >0.5 x 10(9)/l was 14 days (range 11-17 days), and the median time to a platelet count >20 x 10(9)/l was 16 days (range 6-30 days). By 1 month after transplant, nine patients had 100% donor chimerism, while three had mixed donor chimerism. At 3 months, 11 had achieved 100% donor chimerism. No cases of grade III/IV acute GVHD occurred. At a median follow-up interval of 14.7 months (range 4-24), seven patients remained alive, and five remained free of disease.
Bone Marrow Transplantation 04/2004; 33(8):833-7. · 3.75 Impact Factor
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ABSTRACT: Mitochondrial DNA (mtDNA) codes for 13 respiratory chain subunits and is more vulnerable to damage than nuclear DNA due, in part, to a lack of histone protection and a weak repair capacity. While mtDNA alterations have been observed in human cancer, their roles in oncogenesis and chemosensitivity remain unclear. We investigated the relationship between mtDNA mutations, reactive oxygen species (ROS) generation, and clinical outcomes in chronic lymphocytic leukemia (CLL) patients. An analysis of mtDNA from 20 CLL patients revealed that primary CLL cells from patients with prior chemotherapy had a significantly higher frequency of heteroplasmic mutations than did those from untreated patients. Overall, mtDNA mutations appeared to be associated with increased ROS generation. Patients refractory to conventional therapeutic agents tended to have higher mutation rates than patients who responded to treatment. Analysis of paired blood samples from the same patient led to the identification of a heteroplasmic mutation in the cytochrome c oxidase II gene several months after chemotherapy. The mutation was associated with increased ROS generation. Our results suggest for the first time that chemotherapy with DNA-damaging agents may cause mtDNA mutations in primary leukemia cells, which often exist in heteroplasmy, and are associated with increased ROS generation.
Leukemia 09/2003; 17(8):1437-47. · 9.56 Impact Factor
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A-M Tsimberidou,
H M Kantarjian,
E Estey,
J E Cortes,
S Verstovsek,
S Faderl,
D A Thomas,
G Garcia-Manero,
A Ferrajoli,
J T Manning, M J Keating,
M Albitar,
S O'Brien,
F J Giles
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ABSTRACT: Granulocytic sarcoma (GS) is an extramedullary tumor composed of immature myeloid cells. The objectives of this study were to describe the frequency, presenting characteristics, and survival in patients with nonleukemic GS by conducting a review of all untreated patients presenting to the MD Anderson Cancer Center between January 1990 and June 2002. In all, 21 patients with nonleukemic GS, 1520 patients with acute myeloid leukemia (AML), and 402 patients with high-risk myelodysplastic syndrome (MDS) were identified. GS occurred in 1.4% of patients with AML, and 1.1% of patients with AML or high-risk MDSs. The median patient age was 57 years (range, 7-81). Among 20 patients with available cytogenetics in tissue and/or bone marrow, six had chromosome 8 abnormalities. The median follow-up of surviving patients is 12 months (range, 7-75). In all, 20 patients were treated. Patients were treated with AML-type chemotherapy (n=16), chemotherapy and radiotherapy (n=3), or radiotherapy alone (n=1). A total of 13 patients (65%) achieved complete remission and one patient (5%) achieved partial remission. The median overall survival was 20 months (range, 1-75), median overall failure-free survival was 12 months (range, 1-75). The median survival of patients with chromosome 8 abnormalities was 12 months compared with 40 months of those without (P=0.17). Novel therapies for patients with GS are required.
Leukemia 07/2003; 17(6):1100-3. · 9.56 Impact Factor
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ABSTRACT: Resistance to purine analogs is emerging as a major problem in the management of patients with chronic lymphocytic leukemia (CLL). Most of these patients have already been exposed to and have become refractory to alkylating agents. To define the natural history of fludarabine (Fludara) refractory patients with CLL, we reviewed the response to first salvage therapy of 147 patients who were refractory to Fludara or had a remission less than six months in duration after a Fludara-containing regimen. Thirty-three (22%) patients responded to their first salvage attempt. However, the median survival was only 10 months. Responders survived significantly longer than non-responders. The most effective salvage regimens were combinations of purine analogs and cyclophosphamide. Patients still possibly sensitive to alkylating agents had a superior response than alkylating agent resistant or naive patients. Subsequent salvage therapy was administered to 61 patients. The most promising results noted in the group were transplantation and the use of Campath-1H antibody. The major morbidity and cause of death were associated with infections. The probability of infection was most strongly associated with the response to salvage therapy. Gram-positive organisms were most commonly associated with infection. However, gram-negative bacilli or opportunistic infection such as fungi, Pneumocystis carinii, acid-fast bacilli and legionella were prominent causes of infection. Fludara-refractory patients are a poor prognosis group and need more effective therapeutic regimens and well-designed infection prophylactic regimens.
Leukemia and Lymphoma 10/2002; 43(9):1755-62. · 2.58 Impact Factor
