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A pre-clinical model of resistance to induction therapy in pediatric acute lymphoblastic leukemia.

Samuels AL, Beesley AH, Yadav BD, Papa RA, Sutton R, Anderson D, Marshall GM, Cole CH, Kees UR, Lock RB - Blood Cancer J (2014)

Bottom Line: CMap analyses reinforced these features, identifying the cholesterol pathway inhibitor simvastatin (SVT) as a potential therapy to overcome resistance.Combined ex vivo with DEX, SVT was significantly synergistic, yet when administered in vivo with VXLD it did not delay leukemia progression.Synergy of SVT with established chemotherapy may depend on higher drug doses than are tolerable in this model.

View Article: PubMed Central - PubMed

Affiliation: Division of Children's Leukaemia and Cancer Research, Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia.

ABSTRACT
Relapse and acquired drug resistance in T-cell acute lymphoblastic leukemia (T-ALL) remains a significant clinical problem. This study was designed to establish a preclinical model of resistance to induction therapy in childhood T-ALL to examine the emergence of drug resistance and identify novel therapies. Patient-derived T-ALL xenografts in immune-deficient (non-obese diabetic/severe combined immunodeficient) mice were exposed to a four-drug combination of vincristine, dexamethasone (DEX), L-asparaginase and daunorubicin (VXLD). 'Relapse' xenografts were characterized by responses to drugs, changes in gene expression profiles and Connectivity Map (CMap) prediction of strategies to reverse drug resistance. Two of four xenografts developed ex vivo and in vivo drug resistance. Both resistant lines showed altered lipid and cholesterol metabolism, yet they had a distinct drug resistance pattern. CMap analyses reinforced these features, identifying the cholesterol pathway inhibitor simvastatin (SVT) as a potential therapy to overcome resistance. Combined ex vivo with DEX, SVT was significantly synergistic, yet when administered in vivo with VXLD it did not delay leukemia progression. Synergy of SVT with established chemotherapy may depend on higher drug doses than are tolerable in this model. Taken together, we have developed a clinically relevant in vivo model of T-ALL suitable to examine the emergence of drug resistance and to identify novel therapies.

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In vivo drug treatment of T-ALL xenografts. (a) ALL-31, (b) ALL-27, (c) ALL-29 and (d) ALL-33 were treated with either single (VXLD) or multiple (VXLD2) rounds of treatment, or saline (control), to generate lines resistant to multidrug chemotherapy. Acquired drug resistance to single agent ASP (e, f), single agent DNR and VCR (i, j) and single agent DEX, or VXLD combination therapy (g, h) was assessed in ALL-31R (derived from VXLD2-treated ALL-31) and compared with passage-matched ALL-31C, with time course of huCD45+ cells (e, g, i) and survival plots (f, h, j) for the groups of mice in each drug treatment. Baseline engraftment ALL-31C or ALL-31R treated with saline only is indicated in e.
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fig1: In vivo drug treatment of T-ALL xenografts. (a) ALL-31, (b) ALL-27, (c) ALL-29 and (d) ALL-33 were treated with either single (VXLD) or multiple (VXLD2) rounds of treatment, or saline (control), to generate lines resistant to multidrug chemotherapy. Acquired drug resistance to single agent ASP (e, f), single agent DNR and VCR (i, j) and single agent DEX, or VXLD combination therapy (g, h) was assessed in ALL-31R (derived from VXLD2-treated ALL-31) and compared with passage-matched ALL-31C, with time course of huCD45+ cells (e, g, i) and survival plots (f, h, j) for the groups of mice in each drug treatment. Baseline engraftment ALL-31C or ALL-31R treated with saline only is indicated in e.

Mentions: We previously optimized an induction-type regimen of VCR, DEX and ASP (VXL) for pre-clinical ALL studies in NOD/SCID mice.25 To improve the clinical relevance of the model in the current study, we included the anthracycline DNR in the VXL backbone. The maximum tolerated dose of DNR in NOD/SCID mice was 2.5 mg/kg administered i.v. once per week (Supplementary Table 1). At this dose and schedule DNR, delayed disease progression by 8.1 days in the previously characterized T-ALL xenograft ALL-16,17 and when added to the VXL platform (VXLD) extended the progression delay of ALL-31 from 26.4– to 41.0 days (data not shown). Therefore, this dose and schedule of DNR exerted anti-leukemic efficacy in vivo. We next developed protocols for the in vivo selection of drug-resistant xenografts based on the VXLD platform. A 4-week induction schedule was adopted, analogous to the clinical regimen, which clearly delayed disease progression in all four xenografts (Figures 1a–d). The intention was to allow disease reappearance in the peripheral blood and resume cycles of VXLD treatment until the disease progressed through the treatment. Based on tolerability and the proportion of mice with re-emergence of disease, we eventually adopted a protocol consisting of a 4-week block of VXLD, followed at disease re-emergence by a 2-week block of half-dose VXL (Figures 1a–d, and Supplementary Table 2). Re-emerging lines (herein labeled ‘R') were thus harvested after either one block of therapy (‘VXLD') or repeated chemotherapy blocks (‘VXLD2'), respectively. Passage-matched controls (labeled ‘C') were also harvested for each xenograft line.


A pre-clinical model of resistance to induction therapy in pediatric acute lymphoblastic leukemia.

Samuels AL, Beesley AH, Yadav BD, Papa RA, Sutton R, Anderson D, Marshall GM, Cole CH, Kees UR, Lock RB - Blood Cancer J (2014)

In vivo drug treatment of T-ALL xenografts. (a) ALL-31, (b) ALL-27, (c) ALL-29 and (d) ALL-33 were treated with either single (VXLD) or multiple (VXLD2) rounds of treatment, or saline (control), to generate lines resistant to multidrug chemotherapy. Acquired drug resistance to single agent ASP (e, f), single agent DNR and VCR (i, j) and single agent DEX, or VXLD combination therapy (g, h) was assessed in ALL-31R (derived from VXLD2-treated ALL-31) and compared with passage-matched ALL-31C, with time course of huCD45+ cells (e, g, i) and survival plots (f, h, j) for the groups of mice in each drug treatment. Baseline engraftment ALL-31C or ALL-31R treated with saline only is indicated in e.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219466&req=5

fig1: In vivo drug treatment of T-ALL xenografts. (a) ALL-31, (b) ALL-27, (c) ALL-29 and (d) ALL-33 were treated with either single (VXLD) or multiple (VXLD2) rounds of treatment, or saline (control), to generate lines resistant to multidrug chemotherapy. Acquired drug resistance to single agent ASP (e, f), single agent DNR and VCR (i, j) and single agent DEX, or VXLD combination therapy (g, h) was assessed in ALL-31R (derived from VXLD2-treated ALL-31) and compared with passage-matched ALL-31C, with time course of huCD45+ cells (e, g, i) and survival plots (f, h, j) for the groups of mice in each drug treatment. Baseline engraftment ALL-31C or ALL-31R treated with saline only is indicated in e.
Mentions: We previously optimized an induction-type regimen of VCR, DEX and ASP (VXL) for pre-clinical ALL studies in NOD/SCID mice.25 To improve the clinical relevance of the model in the current study, we included the anthracycline DNR in the VXL backbone. The maximum tolerated dose of DNR in NOD/SCID mice was 2.5 mg/kg administered i.v. once per week (Supplementary Table 1). At this dose and schedule DNR, delayed disease progression by 8.1 days in the previously characterized T-ALL xenograft ALL-16,17 and when added to the VXL platform (VXLD) extended the progression delay of ALL-31 from 26.4– to 41.0 days (data not shown). Therefore, this dose and schedule of DNR exerted anti-leukemic efficacy in vivo. We next developed protocols for the in vivo selection of drug-resistant xenografts based on the VXLD platform. A 4-week induction schedule was adopted, analogous to the clinical regimen, which clearly delayed disease progression in all four xenografts (Figures 1a–d). The intention was to allow disease reappearance in the peripheral blood and resume cycles of VXLD treatment until the disease progressed through the treatment. Based on tolerability and the proportion of mice with re-emergence of disease, we eventually adopted a protocol consisting of a 4-week block of VXLD, followed at disease re-emergence by a 2-week block of half-dose VXL (Figures 1a–d, and Supplementary Table 2). Re-emerging lines (herein labeled ‘R') were thus harvested after either one block of therapy (‘VXLD') or repeated chemotherapy blocks (‘VXLD2'), respectively. Passage-matched controls (labeled ‘C') were also harvested for each xenograft line.

Bottom Line: CMap analyses reinforced these features, identifying the cholesterol pathway inhibitor simvastatin (SVT) as a potential therapy to overcome resistance.Combined ex vivo with DEX, SVT was significantly synergistic, yet when administered in vivo with VXLD it did not delay leukemia progression.Synergy of SVT with established chemotherapy may depend on higher drug doses than are tolerable in this model.

View Article: PubMed Central - PubMed

Affiliation: Division of Children's Leukaemia and Cancer Research, Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia.

ABSTRACT
Relapse and acquired drug resistance in T-cell acute lymphoblastic leukemia (T-ALL) remains a significant clinical problem. This study was designed to establish a preclinical model of resistance to induction therapy in childhood T-ALL to examine the emergence of drug resistance and identify novel therapies. Patient-derived T-ALL xenografts in immune-deficient (non-obese diabetic/severe combined immunodeficient) mice were exposed to a four-drug combination of vincristine, dexamethasone (DEX), L-asparaginase and daunorubicin (VXLD). 'Relapse' xenografts were characterized by responses to drugs, changes in gene expression profiles and Connectivity Map (CMap) prediction of strategies to reverse drug resistance. Two of four xenografts developed ex vivo and in vivo drug resistance. Both resistant lines showed altered lipid and cholesterol metabolism, yet they had a distinct drug resistance pattern. CMap analyses reinforced these features, identifying the cholesterol pathway inhibitor simvastatin (SVT) as a potential therapy to overcome resistance. Combined ex vivo with DEX, SVT was significantly synergistic, yet when administered in vivo with VXLD it did not delay leukemia progression. Synergy of SVT with established chemotherapy may depend on higher drug doses than are tolerable in this model. Taken together, we have developed a clinically relevant in vivo model of T-ALL suitable to examine the emergence of drug resistance and to identify novel therapies.

Show MeSH
Related in: MedlinePlus