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Lack of antileukemic activity of rapamycin in elderly patients with acute myeloid leukemia evolving from a myelodysplastic syndrome
Letters to the Editor / Leukemia Research 32 (2008) 1623–1640
Lack of antileukemic activity of rapamycin in elderly patients with acute myeloid leukemia evolving from a myelodysplastic syndrome It was recently demonstrated that the mammalian target of rapamycin (mTOR) is aberrantly regulated in most acute myeloid leukemia (AML) cells and that mTOR inhibition by rapamycin, an immunosuppressant and antiproliferative agent clinically used in the setting of solid-organ and hematopoietic transplants, induces significant clinical responses in patients with different categories of AML [1,2]. Furthermore, rapamycin can prevent leukemia development in mouse models while at the same time restoring normal hematopoietic stem cell function [3]. Given these promising data, thus defining the basis for a new therapeutic strategy for AML patients using mTOR inhibitors, elderly patients with AML evolving from a myelodysplastic syndrome were treated with rapamycin as a single agent. Inclusion criteria and rapamycin treatment were performed as previously described [1]. Inclusion criteria were AML secondary to refractory anemia with excess blasts (World Health Organization (WHO) classification—AML with multilineage dysplasia evolving from a myelodysplastic syndrome [4]), age older than 65 years, Eastern Cooperative Oncology Group (ECOG) performance status less than four, no renal or hepatic function impairment (defined by serum creatinine <150 M, serum bilirubin <35 M and alanine aminotransferase and aspartate aminotransferease <2 times normal) and no active infection. Patients were treated with sirolimus (Rapamune; Wyeth, Pearl River, NY) (orally) 6 mg as loading dose at day 1 then 2 mg per day for a planned time of 28 days, after informed consent. Treatment was continued in patients with evidence of hematologic response, until progression or toxicity. Patients were treated as outpatients with weekly clinical examinations and biologic monitoring (hematologic and biochemical tests) for the first 28 days of treatment. The primary study objective was to determine the response rate. Complete response (CR) was defined by an absolute neutrophil count of more than 1.5 × 109 L−1 , a platelet count of 100 × 109 L−1 or more, and less than 5% of blast cells
1633
in the marrow. Partial response (PR) was defined as a more than 50% reduction in the absolute number of blood blasts or at least a 50% reduction in the percentage of marrow blasts. Of 15 patients enrolled, 7 had undergone treatment with rapamycin at the time of reporting and all of them had evidence of disease progression (Table 1). The lack of significant responses obtained within 21 days of treatment with rapamycin led us to stop the trial; rapamycin was discontinued and cytotoxic drugs, such as low-dose cytarabine or cytarabine plus daunorubicin, were used in order to induce the remission of the disease. At a median follow-up of 3 months (range 1–6), three patients were alive in PR. We found no evidence that rapamycin is an effective treatment for elderly patients with AML evolving from a myelodysplastic syndrome. Comparison of our results with the outcomes of others studies is difficult since the use mTOR inhibitors in hematologic malignancies has been poorly demonstrated [5]. In one pilot study, R´echer et al. [1] showed that rapamycin induced partial responses in 4 of 9 patients with either refractory/relapsed de novo AML or secondary AML; this study, unlike ours, enrolled only one patient with AML evolving from a myelodysplastic syndrome and it is wild accepted that this category of AML often has a worse prognosis. However, a satisfactory explanation for our data remains elusive. At same doses used for renal transplant recipients, all AML patients showed disease progression; one hypothesis is that a therapeutic effect might be achieved with higher doses of rapamycin alone or in combination with other pharmacologic inhibitors or cytotoxic drugs. In this setting, Mahalati and Kahan [6] demonstrated that the whole blood concentrations of rapamycin showed a highly variable inter- and intrapatient biodisponibility suggesting that analogs of rapamycin, with better pharmacologic properties, could be more efficient. A second hypothesis is that AML cells from our patients showed primary resistance to rapamycin; due to the low number of patients, we did not find any correlation between clinical resistance and bioclinical data. Different mechanisms of resistance to rapamycin have been described in vitro and, moreover, some AML cells may also activate other signaling pathways able to overpass mTOR inhibition [7,8]. Whether these mechanisms are found
Table 1 Characteristics and hematologic responses of patients with AML evolving from a myelodysplastic syndrome treated with rapamycin Patient (n◦ )
Age (years)
Cytogenetics
WBC (×109 L−1 ) and peripheral blood blast cell percentage (%) Days of treatment
1 2 3 4 5 6 7
80 82 71 75 76 79 81 a
45,XY 45,XY (+8) 45,XX 45,XX 45,XX (−7q) 45,XY (−5q) 45,XY
1
7
14
21
3.5 (15) 10.3 (31) 5.6 (9) 7.8 (23) 15.1 (43) 2.3 (11) 11.2 (29)
4.7 (12) 11.3 (22) 9.8 (11) 12.3 (25) 24.2 (37) 8.6 (23) 15.2 (34)
17.7 (35) 23.5 (43) 27.6 (28) 32.1 (46) 43.7 (43) 23.7 (34) 32.1 (39)
38.5 (54)a 54.3 (69)a 45.5 (43)a 65.7 (63)a 160.1 (87)a 67.4 (43)a 56.0 (53)a
Hypercellular marrow aspirate with more than 20% blast cells without evidence of CR or PR.
1634
Letters to the Editor / Leukemia Research 32 (2008) 1623–1640
in elderly patients with AML evolving from a myelodysplastic syndrome remains to be determined. Finally, within the experimental framework presented here, our data suggest a lack of antileukemic activity of rapamycin in elderly patients with AML evolving from a myelodysplastic syndrome. Despite our disappointing results we believe that further analysis on these fields will add practical guidance to centers that are conducting treatments for patients with AML.
∗ Corresponding
author. Tel.: +55 12 3921 3766; fax: +55 12 3921 3766. E-mail address: [email protected] (F. Callera) 8 February 2008 Available online 10 April 2008 doi: 10.1016/j.leukres.2008.02.004
Neuropilin-1 is expressed by chronic lymphocytic leukemia B cells Conflict of interest To the Editor, None.
Acknowledgements This study was carried out in the Hospital PIO XII of S˜ao Jos´e dos Campos supported by the Servic¸o de Hematologia do Vale do Para´ıba. No potential conflict of interest relevant to this article was reported. Contributions. Dr. Carlos O. Lopes, Dr. Evandro S. Rosa and Dr. Carla C. Mulin are the staff of the Servic¸o de Hematologia do Vale do Para´ıba and contributed with the treatment component of the study.
References [1] R´echer C, Beyne-Rauzy O, Demur C, Chicanne G, Dos Santos C, Mas VM-D, et al. Antileukemic activity of rapamycin in acute myeloid leukemia. Blood 2005;105:2527–34. [2] R´echer C, Dos Santos C, Demur C, Payrastre B. mTOR, a new therapeutic target in acute myeloid leukemia. Cell Cycle 2005;4(11):1540– 9. [3] Marx J. Cancerˇıs perpetual source? Science 2007;317:1029–31. [4] Vardiman J, Harris N, Brunning R. The World Health Organization (WHO) classification of the myeloid neoplasms. Blood 2002;100(7):2292–302. [5] Panwalkar A, Verstovsek S, Giles FJ. Mammalian target of rapamycin inhibition as therapy for hematologic malignancies. Cancer 2004;100:657–66. [6] Mahalati K, Kahan BD. Clinical pharmacokinetics of sirolimus. Clin Pharmacokinet 2001;40:573–85. [7] Hosoi H, Dilling MB, Liu LN. Studies on the mechanisms of resistance to rapamycin in human cancer cells. Mol Pharmacol 1998;54:815– 24. [8] Huang S, Bjornsti MA, Houghton PJ. Rapamycins: mechanism of action and cellular resistance. Cancer Biol Ther 2003:222–32.
Fernando Callera ∗ Carlos O. Lopes Evandro S. Rosa Carla C. Mulin Servi¸co de Hematologia do Vale do Para´ıba, Rua Antonio Sais 425, 12210-040 S˜ao Jos´e Dos Campos, S˜ao Paulo, Brazil
Primary CLL B cells have been shown to secrete vascular endothelial growth factor (VEGF), and secreted VEGF was shown to increase the resistance of leukemic CLL B cells to spontaneous and drug induced apoptosis through what is believed to be an autocrine loop [1]. We and others have shown that CLL B cells express VEGF receptor 1 (VEGF-R1) and 2 (VEGF-R2) which provide these cells with a capacity for VEGF binding [2]. While these receptors were shown to be expressed on tumor cells and are likely to be involved in both autocrine survival as well as neovascularization in tumor models, there is increasing evidence that another VEGF receptor, neuropilin-1 (NRP-1), is critical in these tumor angiogenic features and most likely involved in VEGF mediated resistance to apoptosis [3]. Aberrant NRP-1 expression has been shown in several solid tumors and acute myeloid leukemia. In the latter, NRP-1 expression was associated with shortened overall survival of these patients [4]. Recently, we have investigated NRP-1 expression in CLL and normal B cells. All CLL patients had a confirmed diagnosis using the National Cancer Institute (NCI) Working Group definition. Patients’ samples utilized in Western blot analysis were from all Rai stages where more than 90% of CD19+ and CD5+ CLL B cells were present as assessed by flow cytometry. Western blot was performed for 10 CLL patients using monoclonal anti-NRP-1 antibodies (Calbiochem, San Diego, CA) and showed NRP-1 protein expression in 7 of 10 patients (Fig. 1A). We also evaluated surface NRP-1 expression by flow cytometry (n = 5) (Fig. 1B). Patients in this cohort were from early Rai stages (0–2) and had a varying degree of lymphocytosis (median, 63,000 × 109 L−1 ; range, 6000–123,000). Isolated mononuclear cells were stained with monoclonal allophycocyanin labeled anti-CD19 antibodies (BD Biosciences, San Jose, CA) and phycoerythrin labeled antiNRP-1 antibodies (Miltenyi Biotec, Auburn, CA) and then analyzed by flow cytometry gating on CD19+ cells. Isotypespecific antibodies were used as controls. NRP-1 expression by flow was seen in two of five patients, but NRP-1 expression was not detected in three of three normal B cells obtained from healthy controls. Our results demonstrate, for the first time, that NRP-1 is expressed by a subset of CLL B cells.
Lack of antileukemic activity of rapamycin in elderly patients with acute myeloid leukemia evolving from a myelodysplastic syndrome It was recently demonstrated that the mammalian target of rapamycin (mTOR) is aberrantly regulated in most acute myeloid leukemia (AML) cells and that mTOR inhibition by rapamycin, an immunosuppressant and antiproliferative agent clinically used in the setting of solid-organ and hematopoietic transplants, induces significant clinical responses in patients with different categories of AML [1,2]. Furthermore, rapamycin can prevent leukemia development in mouse models while at the same time restoring normal hematopoietic stem cell function [3]. Given these promising data, thus defining the basis for a new therapeutic strategy for AML patients using mTOR inhibitors, elderly patients with AML evolving from a myelodysplastic syndrome were treated with rapamycin as a single agent. Inclusion criteria and rapamycin treatment were performed as previously described [1]. Inclusion criteria were AML secondary to refractory anemia with excess blasts (World Health Organization (WHO) classification—AML with multilineage dysplasia evolving from a myelodysplastic syndrome [4]), age older than 65 years, Eastern Cooperative Oncology Group (ECOG) performance status less than four, no renal or hepatic function impairment (defined by serum creatinine <150 M, serum bilirubin <35 M and alanine aminotransferase and aspartate aminotransferease <2 times normal) and no active infection. Patients were treated with sirolimus (Rapamune; Wyeth, Pearl River, NY) (orally) 6 mg as loading dose at day 1 then 2 mg per day for a planned time of 28 days, after informed consent. Treatment was continued in patients with evidence of hematologic response, until progression or toxicity. Patients were treated as outpatients with weekly clinical examinations and biologic monitoring (hematologic and biochemical tests) for the first 28 days of treatment. The primary study objective was to determine the response rate. Complete response (CR) was defined by an absolute neutrophil count of more than 1.5 × 109 L−1 , a platelet count of 100 × 109 L−1 or more, and less than 5% of blast cells
1633
in the marrow. Partial response (PR) was defined as a more than 50% reduction in the absolute number of blood blasts or at least a 50% reduction in the percentage of marrow blasts. Of 15 patients enrolled, 7 had undergone treatment with rapamycin at the time of reporting and all of them had evidence of disease progression (Table 1). The lack of significant responses obtained within 21 days of treatment with rapamycin led us to stop the trial; rapamycin was discontinued and cytotoxic drugs, such as low-dose cytarabine or cytarabine plus daunorubicin, were used in order to induce the remission of the disease. At a median follow-up of 3 months (range 1–6), three patients were alive in PR. We found no evidence that rapamycin is an effective treatment for elderly patients with AML evolving from a myelodysplastic syndrome. Comparison of our results with the outcomes of others studies is difficult since the use mTOR inhibitors in hematologic malignancies has been poorly demonstrated [5]. In one pilot study, R´echer et al. [1] showed that rapamycin induced partial responses in 4 of 9 patients with either refractory/relapsed de novo AML or secondary AML; this study, unlike ours, enrolled only one patient with AML evolving from a myelodysplastic syndrome and it is wild accepted that this category of AML often has a worse prognosis. However, a satisfactory explanation for our data remains elusive. At same doses used for renal transplant recipients, all AML patients showed disease progression; one hypothesis is that a therapeutic effect might be achieved with higher doses of rapamycin alone or in combination with other pharmacologic inhibitors or cytotoxic drugs. In this setting, Mahalati and Kahan [6] demonstrated that the whole blood concentrations of rapamycin showed a highly variable inter- and intrapatient biodisponibility suggesting that analogs of rapamycin, with better pharmacologic properties, could be more efficient. A second hypothesis is that AML cells from our patients showed primary resistance to rapamycin; due to the low number of patients, we did not find any correlation between clinical resistance and bioclinical data. Different mechanisms of resistance to rapamycin have been described in vitro and, moreover, some AML cells may also activate other signaling pathways able to overpass mTOR inhibition [7,8]. Whether these mechanisms are found
Table 1 Characteristics and hematologic responses of patients with AML evolving from a myelodysplastic syndrome treated with rapamycin Patient (n◦ )
Age (years)
Cytogenetics
WBC (×109 L−1 ) and peripheral blood blast cell percentage (%) Days of treatment
1 2 3 4 5 6 7
80 82 71 75 76 79 81 a
45,XY 45,XY (+8) 45,XX 45,XX 45,XX (−7q) 45,XY (−5q) 45,XY
1
7
14
21
3.5 (15) 10.3 (31) 5.6 (9) 7.8 (23) 15.1 (43) 2.3 (11) 11.2 (29)
4.7 (12) 11.3 (22) 9.8 (11) 12.3 (25) 24.2 (37) 8.6 (23) 15.2 (34)
17.7 (35) 23.5 (43) 27.6 (28) 32.1 (46) 43.7 (43) 23.7 (34) 32.1 (39)
38.5 (54)a 54.3 (69)a 45.5 (43)a 65.7 (63)a 160.1 (87)a 67.4 (43)a 56.0 (53)a
Hypercellular marrow aspirate with more than 20% blast cells without evidence of CR or PR.
1634
Letters to the Editor / Leukemia Research 32 (2008) 1623–1640
in elderly patients with AML evolving from a myelodysplastic syndrome remains to be determined. Finally, within the experimental framework presented here, our data suggest a lack of antileukemic activity of rapamycin in elderly patients with AML evolving from a myelodysplastic syndrome. Despite our disappointing results we believe that further analysis on these fields will add practical guidance to centers that are conducting treatments for patients with AML.
∗ Corresponding
author. Tel.: +55 12 3921 3766; fax: +55 12 3921 3766. E-mail address: [email protected] (F. Callera) 8 February 2008 Available online 10 April 2008 doi: 10.1016/j.leukres.2008.02.004
Neuropilin-1 is expressed by chronic lymphocytic leukemia B cells Conflict of interest To the Editor, None.
Acknowledgements This study was carried out in the Hospital PIO XII of S˜ao Jos´e dos Campos supported by the Servic¸o de Hematologia do Vale do Para´ıba. No potential conflict of interest relevant to this article was reported. Contributions. Dr. Carlos O. Lopes, Dr. Evandro S. Rosa and Dr. Carla C. Mulin are the staff of the Servic¸o de Hematologia do Vale do Para´ıba and contributed with the treatment component of the study.
References [1] R´echer C, Beyne-Rauzy O, Demur C, Chicanne G, Dos Santos C, Mas VM-D, et al. Antileukemic activity of rapamycin in acute myeloid leukemia. Blood 2005;105:2527–34. [2] R´echer C, Dos Santos C, Demur C, Payrastre B. mTOR, a new therapeutic target in acute myeloid leukemia. Cell Cycle 2005;4(11):1540– 9. [3] Marx J. Cancerˇıs perpetual source? Science 2007;317:1029–31. [4] Vardiman J, Harris N, Brunning R. The World Health Organization (WHO) classification of the myeloid neoplasms. Blood 2002;100(7):2292–302. [5] Panwalkar A, Verstovsek S, Giles FJ. Mammalian target of rapamycin inhibition as therapy for hematologic malignancies. Cancer 2004;100:657–66. [6] Mahalati K, Kahan BD. Clinical pharmacokinetics of sirolimus. Clin Pharmacokinet 2001;40:573–85. [7] Hosoi H, Dilling MB, Liu LN. Studies on the mechanisms of resistance to rapamycin in human cancer cells. Mol Pharmacol 1998;54:815– 24. [8] Huang S, Bjornsti MA, Houghton PJ. Rapamycins: mechanism of action and cellular resistance. Cancer Biol Ther 2003:222–32.
Fernando Callera ∗ Carlos O. Lopes Evandro S. Rosa Carla C. Mulin Servi¸co de Hematologia do Vale do Para´ıba, Rua Antonio Sais 425, 12210-040 S˜ao Jos´e Dos Campos, S˜ao Paulo, Brazil
Primary CLL B cells have been shown to secrete vascular endothelial growth factor (VEGF), and secreted VEGF was shown to increase the resistance of leukemic CLL B cells to spontaneous and drug induced apoptosis through what is believed to be an autocrine loop [1]. We and others have shown that CLL B cells express VEGF receptor 1 (VEGF-R1) and 2 (VEGF-R2) which provide these cells with a capacity for VEGF binding [2]. While these receptors were shown to be expressed on tumor cells and are likely to be involved in both autocrine survival as well as neovascularization in tumor models, there is increasing evidence that another VEGF receptor, neuropilin-1 (NRP-1), is critical in these tumor angiogenic features and most likely involved in VEGF mediated resistance to apoptosis [3]. Aberrant NRP-1 expression has been shown in several solid tumors and acute myeloid leukemia. In the latter, NRP-1 expression was associated with shortened overall survival of these patients [4]. Recently, we have investigated NRP-1 expression in CLL and normal B cells. All CLL patients had a confirmed diagnosis using the National Cancer Institute (NCI) Working Group definition. Patients’ samples utilized in Western blot analysis were from all Rai stages where more than 90% of CD19+ and CD5+ CLL B cells were present as assessed by flow cytometry. Western blot was performed for 10 CLL patients using monoclonal anti-NRP-1 antibodies (Calbiochem, San Diego, CA) and showed NRP-1 protein expression in 7 of 10 patients (Fig. 1A). We also evaluated surface NRP-1 expression by flow cytometry (n = 5) (Fig. 1B). Patients in this cohort were from early Rai stages (0–2) and had a varying degree of lymphocytosis (median, 63,000 × 109 L−1 ; range, 6000–123,000). Isolated mononuclear cells were stained with monoclonal allophycocyanin labeled anti-CD19 antibodies (BD Biosciences, San Jose, CA) and phycoerythrin labeled antiNRP-1 antibodies (Miltenyi Biotec, Auburn, CA) and then analyzed by flow cytometry gating on CD19+ cells. Isotypespecific antibodies were used as controls. NRP-1 expression by flow was seen in two of five patients, but NRP-1 expression was not detected in three of three normal B cells obtained from healthy controls. Our results demonstrate, for the first time, that NRP-1 is expressed by a subset of CLL B cells.