KRN5500: a novel therapeutic agent with in vitro activity against human B-cell chronic lymphocytic leukemia cells mediates cytotoxicity via the intrinsic pathway of apoptosis

Blood ◽  
2003 ◽  
Vol 101 (11) ◽  
pp. 4547-4550 ◽  
Author(s):  
John C. Byrd ◽  
David M. Lucas ◽  
Andrew P. Mone ◽  
Joshua B. Kitner ◽  
Joseph J. Drabick ◽  
...  

Abstract Therapy of B-cell chronic lymphocytic leukemia (CLL) is currently palliative, emphasizing the need for identification of new therapies for this disease. KRN5500 is a novel agent that has a unique sensitivity pattern in the National Cancer Institute cell line screening panel, suggesting a unique mechanism of action. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 11) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC50) at 4 hours, 24 hours, and 4 days at KRN5500 concentrations of 2.50 μM, 0.276 μM, and 0.139 μM, respectively. KRN5500 induced cellular injury via caspase-dependent apoptosis involving the intrinsic mitochondrial (caspase-9) initiating caspase and caspase-3 effector caspase; however, expression of the antiapoptotic mitochondrial membrane protein Bcl-2 was unaffected. These data demonstrate KRN5500 has significant in vitro activity against human CLL cells, thus providing support for introduction of this agent into clinical trials for patients with CLL.

Blood ◽  
1999 ◽  
Vol 94 (4) ◽  
pp. 1401-1408 ◽  
Author(s):  
John C. Byrd ◽  
Charlotte Shinn ◽  
Rajani Ravi ◽  
Carl R. Willis ◽  
Jamie K. Waselenko ◽  
...  

Abstract Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity of therapeutic agents toward normal residual immune cells and inherent drug resistance. Identification of agents that spare normal immune effector cells, thus facilitating addition of immune-based therapies, and that modulate factors associated with drug resistance in CLL might represent a major therapeutic advance. Depsipeptide (FR901228) is a novel agent entering clinical trials that has selective in vitro activity against resistant leukemia cell lines. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 10) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC50) at 4 hours, 24 hours, and 4 days at depsipeptide concentrations of 0.038, 0.024, and 0.015 μmol/L, respectively. Depsipeptide had marked selective cytotoxicity when compared with normal blood mononuclear cells, in which the LC50 was 3.44 μmol/L at 4 hours (P = .03), 0.965 μmol/L at 24 hours (P = .01), and 0.0318 μmol/L at 96 hours (P = .04). Inhibition of bone marrow progenitor cell growth was also minimal after incubation with 0.015 μmol/L (19% inhibition of colony forming unit-granulocyte-macrophage [CFU-GM]; 17% inhibition burst forming unit-erythroid [BFU-E]) and 3.44 μmol/L (24% inhibition of CFU-GM; 57% inhibition BFU-E) of depsipeptide for 4 hours, followed by a 14-day incubation period. Expression of apoptotic proteins after depsipeptide exposure (0.015 μmol/L) included no change in bcl-2, elevation of bax, and decreased expression of p27. These data demonstrate that depsipeptide has significant selective in vitro activity against human CLL cells concurrent with favorable alterations of the bcl-2:bax protein ratio and decrease in p27 expression. Such findings strongly support the early introduction of depsipeptide into clinical trials for patients with CLL.


Blood ◽  
1999 ◽  
Vol 94 (4) ◽  
pp. 1401-1408 ◽  
Author(s):  
John C. Byrd ◽  
Charlotte Shinn ◽  
Rajani Ravi ◽  
Carl R. Willis ◽  
Jamie K. Waselenko ◽  
...  

Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity of therapeutic agents toward normal residual immune cells and inherent drug resistance. Identification of agents that spare normal immune effector cells, thus facilitating addition of immune-based therapies, and that modulate factors associated with drug resistance in CLL might represent a major therapeutic advance. Depsipeptide (FR901228) is a novel agent entering clinical trials that has selective in vitro activity against resistant leukemia cell lines. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 10) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC50) at 4 hours, 24 hours, and 4 days at depsipeptide concentrations of 0.038, 0.024, and 0.015 μmol/L, respectively. Depsipeptide had marked selective cytotoxicity when compared with normal blood mononuclear cells, in which the LC50 was 3.44 μmol/L at 4 hours (P = .03), 0.965 μmol/L at 24 hours (P = .01), and 0.0318 μmol/L at 96 hours (P = .04). Inhibition of bone marrow progenitor cell growth was also minimal after incubation with 0.015 μmol/L (19% inhibition of colony forming unit-granulocyte-macrophage [CFU-GM]; 17% inhibition burst forming unit-erythroid [BFU-E]) and 3.44 μmol/L (24% inhibition of CFU-GM; 57% inhibition BFU-E) of depsipeptide for 4 hours, followed by a 14-day incubation period. Expression of apoptotic proteins after depsipeptide exposure (0.015 μmol/L) included no change in bcl-2, elevation of bax, and decreased expression of p27. These data demonstrate that depsipeptide has significant selective in vitro activity against human CLL cells concurrent with favorable alterations of the bcl-2:bax protein ratio and decrease in p27 expression. Such findings strongly support the early introduction of depsipeptide into clinical trials for patients with CLL.


2001 ◽  
Vol 25 (6) ◽  
pp. 435-440 ◽  
Author(s):  
Jamie K Waselenko ◽  
Michael R Grever ◽  
Charlotte A Shinn ◽  
Ian W Flinn ◽  
John C Byrd

Blood ◽  
1998 ◽  
Vol 92 (10) ◽  
pp. 3804-3816 ◽  
Author(s):  
John C. Byrd ◽  
Charlotte Shinn ◽  
Jamie K. Waselenko ◽  
Ephraim J. Fuchs ◽  
Teresa A. Lehman ◽  
...  

Abstract Flavopiridol has been reported to induce apoptosis in lymphoid cell lines via downregulation of bcl-2. The in vitro activity of flavopiridol against human chronic lymphocytic leukemia (CLL) cells and potential mechanisms of action for inducing cytotoxicity were studied. The in vitro viability of mononuclear cells from CLL patients (n = 11) was reduced by 50% at 4 hours, 24 hours, and 4 days at a flavopiridol concentration of 1.15 μmol/L (95% confidence interval [CI] ±0.31), 0.18 μmol/L (95% CI ±0.04), and 0.16 μmol/L (95% CI ±0.04), respectively. Loss of viability in human CLL cells correlated with early induction of apoptosis. Exposure of CLL cells to 0.18 μmol/L of flavopiridol resulted in both decreased expression of p53 protein and cleavage of the caspase-3 zymogen 32-kD protein with the appearance of its 20-kD subunit. Contrasting observations of others in tumor cell lines, flavopiridol cytotoxicity in CLL cells did not correlate with changes in bcl-2 protein expression alterations. We evaluated flavopiridol’s dependence on intact p53 by exposing splenocytes from wild-type (p53+/+) and p53 null (p53−/−) mice that demonstrated no preferential cytotoxicity as compared with a marked differential with F-ara-a and radiation. Incubation of CLL cells with antiapoptotic cytokine interleukin-4 (IL-4) did not alter the LC50 of flavopiridol, as compared with a marked elevation noted with F-ara-a in the majority of patients tested. These data demonstrate that flavopiridol has significant in vitro activity against human CLL cells through activation of caspase-3, which appears to occur independently of bcl-2 modulation, the presence of IL-4, or p53 status. Such findings strongly support the early introduction of flavopiridol into clinical trials for patients with B-CLL.


Blood ◽  
2001 ◽  
Vol 97 (9) ◽  
pp. 2777-2783 ◽  
Author(s):  
Luisa Granziero ◽  
Paolo Ghia ◽  
Paola Circosta ◽  
Daniela Gottardi ◽  
Giuliana Strola ◽  
...  

Abstract In B-cell chronic lymphocytic leukemia (B-CLL), defective apoptosis causes the accumulation of mature CD5+ B cells in lymphoid organs, bone marrow (BM), and peripheral blood (PB). These cells are the progeny of a proliferating pool that feeds the accumulating compartment. The authors sought to determine which molecular mechanisms govern the proliferating pool, how they relate to apoptosis, and what the role is of the microenvironment. To begin to resolve these problems, the expression and modulation of the family of inhibitor of apoptosis proteins (IAPs) were investigated, with consideration given to the possibility that physiological stimuli, such as CD40 ligand (CD40L), available to B cells in the microenvironment, might modulate IAP expression. The in vitro data on mononuclear cells from PB or BM of 30 patients demonstrate that B-CLL cells on CD40 stimulation express Survivin and that Survivin is the only IAP whose expression is induced by CD40L. Through immunohistochemistry, in vivo Survivin expression in lymph node (LN) and BM biopsies was evaluated. In reactive LN, Survivin was detected only in highly proliferating germinal center cells. In LN from patients with B-CLL, Survivin was detected only in pseudofollicles. Pseudofollicle Survivin+ cells were actively proliferating and, in contrast to Survivin+ B cells found in normal GC, were Bcl-2+. In B-CLL BM biopsies, CD5+, Survivin+ cells were observed in clusters interspersed with T cells. These findings establish that Survivin controls the B-CLL proliferative pool interfacing apoptosis and that its expression may be modulated by microenvironmental stimuli.


Blood ◽  
1998 ◽  
Vol 92 (10) ◽  
pp. 3804-3816 ◽  
Author(s):  
John C. Byrd ◽  
Charlotte Shinn ◽  
Jamie K. Waselenko ◽  
Ephraim J. Fuchs ◽  
Teresa A. Lehman ◽  
...  

Flavopiridol has been reported to induce apoptosis in lymphoid cell lines via downregulation of bcl-2. The in vitro activity of flavopiridol against human chronic lymphocytic leukemia (CLL) cells and potential mechanisms of action for inducing cytotoxicity were studied. The in vitro viability of mononuclear cells from CLL patients (n = 11) was reduced by 50% at 4 hours, 24 hours, and 4 days at a flavopiridol concentration of 1.15 μmol/L (95% confidence interval [CI] ±0.31), 0.18 μmol/L (95% CI ±0.04), and 0.16 μmol/L (95% CI ±0.04), respectively. Loss of viability in human CLL cells correlated with early induction of apoptosis. Exposure of CLL cells to 0.18 μmol/L of flavopiridol resulted in both decreased expression of p53 protein and cleavage of the caspase-3 zymogen 32-kD protein with the appearance of its 20-kD subunit. Contrasting observations of others in tumor cell lines, flavopiridol cytotoxicity in CLL cells did not correlate with changes in bcl-2 protein expression alterations. We evaluated flavopiridol’s dependence on intact p53 by exposing splenocytes from wild-type (p53+/+) and p53 null (p53−/−) mice that demonstrated no preferential cytotoxicity as compared with a marked differential with F-ara-a and radiation. Incubation of CLL cells with antiapoptotic cytokine interleukin-4 (IL-4) did not alter the LC50 of flavopiridol, as compared with a marked elevation noted with F-ara-a in the majority of patients tested. These data demonstrate that flavopiridol has significant in vitro activity against human CLL cells through activation of caspase-3, which appears to occur independently of bcl-2 modulation, the presence of IL-4, or p53 status. Such findings strongly support the early introduction of flavopiridol into clinical trials for patients with B-CLL.


Blood ◽  
1988 ◽  
Vol 71 (4) ◽  
pp. 1012-1020 ◽  
Author(s):  
JS Moore ◽  
MB Prystowsky ◽  
RG Hoover ◽  
EC Besa ◽  
PC Nowell

The consistent occurrence of T cell abnormalities in patients with B cell chronic lymphocytic leukemia (B-CLL) suggest that the non- neoplastic host T cells may be involved in the pathogenesis of this B cell neoplasm. Because potential defects of immunoglobulin regulation are evident in B-CLL patients, we investigated one aspect of this by studying the T cell-mediated immunoglobulin isotype-specific immunoregulatory circuit in B-CLL. The existence of class-specific immunoglobulin regulatory mechanisms mediated by Fc receptor-bearing T cells (FcR + T) through soluble immunoglobulin binding factors (IgBFs) has been well established in many experimental systems. IgBFs can both suppress and enhance B cell activity in an isotype-specific manner. We investigated the apparently abnormal IgA regulation in a B-CLL patient (CLL249) whose B cells secrete primarily IgA in vitro. Enumeration of FcR + T cells showed a disproportionate increase in IgA FcR + T cells in the peripheral blood of this patient. Our studies showed that the neoplastic B cells were not intrinsically unresponsive to the suppressing component of IgABF produced from normal T cells, but rather the IgABF produced by the CLL249 host T cells was defective. CLL249 IgABF was unable to suppress IgA secretion by host or normal B cells and enhanced the in vitro proliferation of the host B cells. Size fractionation of both normal and CLL249 IgABF by gel-filtration high- performance liquid chromatography (HPLC) demonstrated differences in the ultraviolet-absorbing components of IgABF obtained from normal T cells v that from our patient with defective IgA regulation. Such T cell dysfunction may not be restricted to IgA regulation, since we have found similar expansion of isotype-specific FcR + T cells associated with expansion of the corresponding B cell clone in other patients with B-CLL. These data suggest that this T cell-mediated regulatory circuit could be significantly involved in the pathogenesis of B-CLL.


Blood ◽  
1987 ◽  
Vol 69 (6) ◽  
pp. 1667-1673 ◽  
Author(s):  
I Touw ◽  
L Dorssers ◽  
B Lowenberg

Abstract To determine the growth properties of B cell chronic lymphocytic leukemia (B CLL) and to identify possible abnormalities thereof, we examined the in vitro action of interleukin 2 (IL2) in four patients. Using radiolabeled IL2 and monoclonal antibodies reactive with IL2 membrane receptors we show that CLL cells, after their activation in vitro, express IL2 receptors of a high- as well as a low-affinity type, exactly as has been reported for normal T and B blasts. In three of the four reported cases, CLL proliferation (measured with 3H-thymidine incorporation) depended on the addition of phytohemagglutinin (PHA) to activate the cells and IL2 (optimal concentration, 10 to 100 U IL2/mL). In contrast, the cells of the fourth case of CLL (CLL-4) proliferated in an autonomous fashion, ie, without a need for PHA and IL2 in culture. Specific blocking of the IL2-binding sites with anti-IL2 receptor monoclonal antibodies almost completely inhibited the proliferation of these cells, which indicated that functional IL2 receptors were required for the autonomous proliferation. The demonstration of low concentrations of IL2 activity in the culture medium conditioned by the cells suggests that endogenous IL2 had been responsible for the spontaneous 3H-thymidine uptake by the CLL cells of patient 4. However, we were unable to extract IL2 mRNA from the cells (neither fresh nor after various in vitro incubations) in quantities detectable by Northern blot analysis that would prove that the CLL cells of patient 4 were actively synthesizing IL2 during culture. Thus, individual cases of B CLL are subject to variable growth regulation involving functional IL2 receptors on the cell surface: after activation with PHA the cells respond to exogenous IL2 in a fashion similar to normal B lymphocytes, or the cells are stimulated by endogenous IL2 (or an IL2-like activity) and do not require activation with PHA.


Blood ◽  
1984 ◽  
Vol 64 (3) ◽  
pp. 667-671 ◽  
Author(s):  
F Lauria ◽  
D Raspadori ◽  
S Tura

Abstract Abnormalities of T lymphocytes in B cell chronic lymphocytic leukemia (B-CLL) have been extensively documented by several immunologic investigations. Following recent studies pointing to the favorable effect of TP-1, a partially purified extract of calf thymus, on the T cell-mediated immunity of several diseases, including Hodgkin's disease, we have used monoclonal antibodies and the enriched T lymphocytes of 16 untreated B-CLL patients to evaluate the proportion of T cell subsets before and after the administration of TP-1. In addition, the proliferative response to phytohemagglutinin (PHA) and the helper function in a pokeweed mitogen (PWM) system were assessed. In ten cases, the effect of TP-1 was also studied in vitro by evaluating the same parameters before and after incubation of B-CLL T cells with the drug. The study demonstrated that in vivo administration of TP-1 increases significantly (P less than .001) the proportion of the defective helper/inducer T cell population (OKT4-positive cells) in B-CLL, leading to a near normal OKT4/OKT8 ratio. Furthermore, the improved phenotypic profile was accompanied by an increased proliferative response to PHA and, in particular, by a significant increase (P less than .01) of T helper capacity; this increase was, however, insufficient to enable the normalization of the serum immunoglobulin levels. The in vitro incubation of B-CLL T lymphocytes did not succeed in producing significant modifications in distribution and function.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 53-53 ◽  
Author(s):  
Krzysztof Giannopoulos ◽  
Iwona Hus ◽  
Li Li ◽  
Agnieszka Bojarska-Junak ◽  
Jochen Greiner ◽  
...  

Abstract Definition of appropriate target antigens might open new avenues to antigen targeted immunotherapies for patients with B-cell chronic lymphocytic leukemia (B-CLL). We screened the mRNA expression of tumor associated antigens (TAAs), from the literature (fibromodulin, survivin, OFA-iLRP, BAGE, G250, MAGE1, PRAME, proteinase, Syntaxin, hTERT, WT-1), and TAAs defined earlier by serological analysis of cDNA expression libraries from leukemic cells (PINCH, HSJ2, MAZ, MPP11, RHAMM/CD168, NY-Ren60). Peripheral blood mononuclear cells from 43 B-CLL patients and 20 healthy volunteers (HVs) were examined by conventional and quantitative RT-PCR. mRNA of RHAMM/CD168, fibromodulin, syntaxin and NY-Ren60 was expressed in 55–90%, mRNA of HSJ2, MAZ and OFA-iLRP in 90–100% of the patients. No expression of WT-1, h-TERT, BAGE, G250, MAGE1 and survivin was observed. Low (2–20%) expression frequencies of MPP11, PINCH, PRAME and proteinase were detected. RHAMM/CD168, fibromodulin, PRAME and MPP11 showed expression in B-CLL patients, but not in HVs. Because of the exquisite tissue expression of RHAMM/CD168 and its high expression frequency in B-CLL patients even in early stages of disease, mixed lymphocyte peptide culture (MLPC), enzyme-linked immunosorbent spot (ELISPOT) and flow cytometry were performed for antigen specific T cells. In MLPC, RHAMM specific responses by CD8+HLA-A2/R3tetramer+CCR7-CD45RAhigh effector T cells were detected. Moreover, we observed an enhanced RHAMM/CD168 specific CD8+ T cell response after vaccination in one from four HLA-A2 positive B-CLL patients vaccinated with tumor cell lysate pulsed dendritic cells. Therefore, RHAMM/CD168 is an interesting candidate antigen for future immunotherapies in both ZAP-70 (+) and ZAP-70 (−) B-CLL patients.


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