DYNAMICS OF EARLY RESPONSE TO TREATMENT OF CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA IS ASSOCIATED WITH GENE DEFECTS
(Abstract release date: 05/19/16)
EHA Library. Pastorczak A. 06/09/16; 132389; E840
Dr. Agata Pastorczak
Contributions
Contributions
Abstract
Abstract: E840
Type: Eposter Presentation
Background
Genetic abnormalities such as BCR-ABL1 translocations, MLL and CRLF2 rearrangements and IKZF1 deletions influence blast clearance during induction phase of childhood B-cell precursor ALL (BCP-ALL). Minimal residual disease (MRD) at different time-points of the induction protocol reflects chemosensitivity and may provide information about resistance of leukemic cells to cytotoxic drugs.
Aims
We investigated early response to treatment at three time-points of induction protocol (days 8, day 15 and 33) in patients with childhood ALL with respect to genetic abnormalities.
Methods
481 children (median age 4.33 yrs), with newly diagnosed BCP-ALL treated between 02-2009 and 08-2015 with the ALL-IC BFM09 protocol in centers of the Polish Pediatric Leukemia/Lymphoma Study Group were enrolled into analysis. Targeted copy number screening was performed on available DNA samples (n=457) using the P335-B2 SALSA MLPA kit (MRC-Holland, Netherlands). IKZF1 deletions were confirmed with breakpoint-specific multiplex-PCR. CRLF2 protein expression on leukemic cells was determined by flow cytometry (FCM). Steroid resistance was defined as the presence of ≥1000 leukemic cells/µl of peripheral blood after 7 days of steroid therapy. MRD was measured at day 15 (MRD15) and day 33 (MRD33) of induction therapy using 8-color flow cytometry. Chemosensitivity of leukemic cells to L-asparaginase, antracyclines and steroids was tested in vitro using an MTT assay (n=27).
Results
The frequency of cytogenetic abnormalities and microdeletions in selected genes were as follow: BCR-ABL1 fusion n=11 (2.4%), MLL rearrangements n=24 (5.2%), IKZF1del n=96 (20%), PAX5 del n=100 (22%), PAR1 del n= 42 (10%), CDKN2A del n=128 (28%), CDKN2B del (26%), BTG1 del n=39 (8.5%), ETV6 del n=101 (22%), EBF1 del n=21 (4.5%), RB1 del n=30 (6.5%). TLSPR expression was observed in 6% of patients (22/358). Poor steroid response was present in 42 cases (42/452=9.3%) and was not associated (all p>0.15) with any of the analyzed genetic factors. Median MRD15 and MRD33 were 5.67% and 0.01% respectively. In univariate analysis median MRD level at day 15 was significantly higher among patients with BCR-ABL1 fusion [12.69(2.5-37.78)% vs 0.31(0.03–3.28)% p=6x10-4], IKZF1del [1.005(0.072-12.54)% vs 0.3(0.03-2.7)%, p=4x10-4] and ETV6del [0.6(0.075-6.615)% vs 0.32(0.029-3.94)%, p=0.02]. Also median MRD level at day 33 was elevated in patients with BCR-ABL1 fusion [0.03(0.0001-0.08)% vs 1x10-4(0.0001-0.005)%, p=0.02] and in patients with IKZF1 deletion [1x10-4(0.0001-0.05)% vs 1x10-4(0.0001-0.003)%, p=0.02]. Multivariate analysis of MRD15, MRD33 and ΔMRD was done for variables with univariate significance of p<0.15 (log10WBC, age at diagnosis, sex, poor steroid response, hypodiploidy, MLL rearrangements, BCR-ABL1 fusion, IKZF1 del, ETV6 del, EBF1 del, PAR1 del). A mixed effects model was used to evaluate intraindividual changes of MRD15 and MRD33 and factored in genetic covariates. The following variables were significant for MRD15 and MRD33 timepoints: log10WBC (β=0.28, p=1x10-7) and (β=0.09, p=0.05), age at diagnosis (β=0.22, p=1x10-7) and (β=0.23, p=1x10-6), IKZF1 del (β=0.14, p=1x10-3) and (β=0.08, p=0.08), respectively. Additionally the following variables were significantly associated with the absolute difference of MRD between MRD33 and MRD15: logWBC (β=-0.15, p=4x10-4), steroid resistance (β=-0.38, p=1x10-6), IKZF1 del (β=-0.19, p=2x10-2), and PAR1 del (β=-0.13, p=3x10-3). MTT confirmed increased resistance to asparaginase of IKZF1 del positive blasts (p=0.01).
Conclusion
Poorer blast clearance during induction protocol in ALL patients harboring IKZF1 deletions may result partly from chemoresistance to L-ASP, which was noted for the first time in both clinical and in vitro settings.
Session topic: E-poster
Keyword(s): Acute lymphoblastic leukemia, Gene deletion, Minimal residual disease (MRD)
Type: Eposter Presentation
Background
Genetic abnormalities such as BCR-ABL1 translocations, MLL and CRLF2 rearrangements and IKZF1 deletions influence blast clearance during induction phase of childhood B-cell precursor ALL (BCP-ALL). Minimal residual disease (MRD) at different time-points of the induction protocol reflects chemosensitivity and may provide information about resistance of leukemic cells to cytotoxic drugs.
Aims
We investigated early response to treatment at three time-points of induction protocol (days 8, day 15 and 33) in patients with childhood ALL with respect to genetic abnormalities.
Methods
481 children (median age 4.33 yrs), with newly diagnosed BCP-ALL treated between 02-2009 and 08-2015 with the ALL-IC BFM09 protocol in centers of the Polish Pediatric Leukemia/Lymphoma Study Group were enrolled into analysis. Targeted copy number screening was performed on available DNA samples (n=457) using the P335-B2 SALSA MLPA kit (MRC-Holland, Netherlands). IKZF1 deletions were confirmed with breakpoint-specific multiplex-PCR. CRLF2 protein expression on leukemic cells was determined by flow cytometry (FCM). Steroid resistance was defined as the presence of ≥1000 leukemic cells/µl of peripheral blood after 7 days of steroid therapy. MRD was measured at day 15 (MRD15) and day 33 (MRD33) of induction therapy using 8-color flow cytometry. Chemosensitivity of leukemic cells to L-asparaginase, antracyclines and steroids was tested in vitro using an MTT assay (n=27).
Results
The frequency of cytogenetic abnormalities and microdeletions in selected genes were as follow: BCR-ABL1 fusion n=11 (2.4%), MLL rearrangements n=24 (5.2%), IKZF1del n=96 (20%), PAX5 del n=100 (22%), PAR1 del n= 42 (10%), CDKN2A del n=128 (28%), CDKN2B del (26%), BTG1 del n=39 (8.5%), ETV6 del n=101 (22%), EBF1 del n=21 (4.5%), RB1 del n=30 (6.5%). TLSPR expression was observed in 6% of patients (22/358). Poor steroid response was present in 42 cases (42/452=9.3%) and was not associated (all p>0.15) with any of the analyzed genetic factors. Median MRD15 and MRD33 were 5.67% and 0.01% respectively. In univariate analysis median MRD level at day 15 was significantly higher among patients with BCR-ABL1 fusion [12.69(2.5-37.78)% vs 0.31(0.03–3.28)% p=6x10-4], IKZF1del [1.005(0.072-12.54)% vs 0.3(0.03-2.7)%, p=4x10-4] and ETV6del [0.6(0.075-6.615)% vs 0.32(0.029-3.94)%, p=0.02]. Also median MRD level at day 33 was elevated in patients with BCR-ABL1 fusion [0.03(0.0001-0.08)% vs 1x10-4(0.0001-0.005)%, p=0.02] and in patients with IKZF1 deletion [1x10-4(0.0001-0.05)% vs 1x10-4(0.0001-0.003)%, p=0.02]. Multivariate analysis of MRD15, MRD33 and ΔMRD was done for variables with univariate significance of p<0.15 (log10WBC, age at diagnosis, sex, poor steroid response, hypodiploidy, MLL rearrangements, BCR-ABL1 fusion, IKZF1 del, ETV6 del, EBF1 del, PAR1 del). A mixed effects model was used to evaluate intraindividual changes of MRD15 and MRD33 and factored in genetic covariates. The following variables were significant for MRD15 and MRD33 timepoints: log10WBC (β=0.28, p=1x10-7) and (β=0.09, p=0.05), age at diagnosis (β=0.22, p=1x10-7) and (β=0.23, p=1x10-6), IKZF1 del (β=0.14, p=1x10-3) and (β=0.08, p=0.08), respectively. Additionally the following variables were significantly associated with the absolute difference of MRD between MRD33 and MRD15: logWBC (β=-0.15, p=4x10-4), steroid resistance (β=-0.38, p=1x10-6), IKZF1 del (β=-0.19, p=2x10-2), and PAR1 del (β=-0.13, p=3x10-3). MTT confirmed increased resistance to asparaginase of IKZF1 del positive blasts (p=0.01).
Conclusion
Poorer blast clearance during induction protocol in ALL patients harboring IKZF1 deletions may result partly from chemoresistance to L-ASP, which was noted for the first time in both clinical and in vitro settings.
Session topic: E-poster
Keyword(s): Acute lymphoblastic leukemia, Gene deletion, Minimal residual disease (MRD)
Abstract: E840
Type: Eposter Presentation
Background
Genetic abnormalities such as BCR-ABL1 translocations, MLL and CRLF2 rearrangements and IKZF1 deletions influence blast clearance during induction phase of childhood B-cell precursor ALL (BCP-ALL). Minimal residual disease (MRD) at different time-points of the induction protocol reflects chemosensitivity and may provide information about resistance of leukemic cells to cytotoxic drugs.
Aims
We investigated early response to treatment at three time-points of induction protocol (days 8, day 15 and 33) in patients with childhood ALL with respect to genetic abnormalities.
Methods
481 children (median age 4.33 yrs), with newly diagnosed BCP-ALL treated between 02-2009 and 08-2015 with the ALL-IC BFM09 protocol in centers of the Polish Pediatric Leukemia/Lymphoma Study Group were enrolled into analysis. Targeted copy number screening was performed on available DNA samples (n=457) using the P335-B2 SALSA MLPA kit (MRC-Holland, Netherlands). IKZF1 deletions were confirmed with breakpoint-specific multiplex-PCR. CRLF2 protein expression on leukemic cells was determined by flow cytometry (FCM). Steroid resistance was defined as the presence of ≥1000 leukemic cells/µl of peripheral blood after 7 days of steroid therapy. MRD was measured at day 15 (MRD15) and day 33 (MRD33) of induction therapy using 8-color flow cytometry. Chemosensitivity of leukemic cells to L-asparaginase, antracyclines and steroids was tested in vitro using an MTT assay (n=27).
Results
The frequency of cytogenetic abnormalities and microdeletions in selected genes were as follow: BCR-ABL1 fusion n=11 (2.4%), MLL rearrangements n=24 (5.2%), IKZF1del n=96 (20%), PAX5 del n=100 (22%), PAR1 del n= 42 (10%), CDKN2A del n=128 (28%), CDKN2B del (26%), BTG1 del n=39 (8.5%), ETV6 del n=101 (22%), EBF1 del n=21 (4.5%), RB1 del n=30 (6.5%). TLSPR expression was observed in 6% of patients (22/358). Poor steroid response was present in 42 cases (42/452=9.3%) and was not associated (all p>0.15) with any of the analyzed genetic factors. Median MRD15 and MRD33 were 5.67% and 0.01% respectively. In univariate analysis median MRD level at day 15 was significantly higher among patients with BCR-ABL1 fusion [12.69(2.5-37.78)% vs 0.31(0.03–3.28)% p=6x10-4], IKZF1del [1.005(0.072-12.54)% vs 0.3(0.03-2.7)%, p=4x10-4] and ETV6del [0.6(0.075-6.615)% vs 0.32(0.029-3.94)%, p=0.02]. Also median MRD level at day 33 was elevated in patients with BCR-ABL1 fusion [0.03(0.0001-0.08)% vs 1x10-4(0.0001-0.005)%, p=0.02] and in patients with IKZF1 deletion [1x10-4(0.0001-0.05)% vs 1x10-4(0.0001-0.003)%, p=0.02]. Multivariate analysis of MRD15, MRD33 and ΔMRD was done for variables with univariate significance of p<0.15 (log10WBC, age at diagnosis, sex, poor steroid response, hypodiploidy, MLL rearrangements, BCR-ABL1 fusion, IKZF1 del, ETV6 del, EBF1 del, PAR1 del). A mixed effects model was used to evaluate intraindividual changes of MRD15 and MRD33 and factored in genetic covariates. The following variables were significant for MRD15 and MRD33 timepoints: log10WBC (β=0.28, p=1x10-7) and (β=0.09, p=0.05), age at diagnosis (β=0.22, p=1x10-7) and (β=0.23, p=1x10-6), IKZF1 del (β=0.14, p=1x10-3) and (β=0.08, p=0.08), respectively. Additionally the following variables were significantly associated with the absolute difference of MRD between MRD33 and MRD15: logWBC (β=-0.15, p=4x10-4), steroid resistance (β=-0.38, p=1x10-6), IKZF1 del (β=-0.19, p=2x10-2), and PAR1 del (β=-0.13, p=3x10-3). MTT confirmed increased resistance to asparaginase of IKZF1 del positive blasts (p=0.01).
Conclusion
Poorer blast clearance during induction protocol in ALL patients harboring IKZF1 deletions may result partly from chemoresistance to L-ASP, which was noted for the first time in both clinical and in vitro settings.
Session topic: E-poster
Keyword(s): Acute lymphoblastic leukemia, Gene deletion, Minimal residual disease (MRD)
Type: Eposter Presentation
Background
Genetic abnormalities such as BCR-ABL1 translocations, MLL and CRLF2 rearrangements and IKZF1 deletions influence blast clearance during induction phase of childhood B-cell precursor ALL (BCP-ALL). Minimal residual disease (MRD) at different time-points of the induction protocol reflects chemosensitivity and may provide information about resistance of leukemic cells to cytotoxic drugs.
Aims
We investigated early response to treatment at three time-points of induction protocol (days 8, day 15 and 33) in patients with childhood ALL with respect to genetic abnormalities.
Methods
481 children (median age 4.33 yrs), with newly diagnosed BCP-ALL treated between 02-2009 and 08-2015 with the ALL-IC BFM09 protocol in centers of the Polish Pediatric Leukemia/Lymphoma Study Group were enrolled into analysis. Targeted copy number screening was performed on available DNA samples (n=457) using the P335-B2 SALSA MLPA kit (MRC-Holland, Netherlands). IKZF1 deletions were confirmed with breakpoint-specific multiplex-PCR. CRLF2 protein expression on leukemic cells was determined by flow cytometry (FCM). Steroid resistance was defined as the presence of ≥1000 leukemic cells/µl of peripheral blood after 7 days of steroid therapy. MRD was measured at day 15 (MRD15) and day 33 (MRD33) of induction therapy using 8-color flow cytometry. Chemosensitivity of leukemic cells to L-asparaginase, antracyclines and steroids was tested in vitro using an MTT assay (n=27).
Results
The frequency of cytogenetic abnormalities and microdeletions in selected genes were as follow: BCR-ABL1 fusion n=11 (2.4%), MLL rearrangements n=24 (5.2%), IKZF1del n=96 (20%), PAX5 del n=100 (22%), PAR1 del n= 42 (10%), CDKN2A del n=128 (28%), CDKN2B del (26%), BTG1 del n=39 (8.5%), ETV6 del n=101 (22%), EBF1 del n=21 (4.5%), RB1 del n=30 (6.5%). TLSPR expression was observed in 6% of patients (22/358). Poor steroid response was present in 42 cases (42/452=9.3%) and was not associated (all p>0.15) with any of the analyzed genetic factors. Median MRD15 and MRD33 were 5.67% and 0.01% respectively. In univariate analysis median MRD level at day 15 was significantly higher among patients with BCR-ABL1 fusion [12.69(2.5-37.78)% vs 0.31(0.03–3.28)% p=6x10-4], IKZF1del [1.005(0.072-12.54)% vs 0.3(0.03-2.7)%, p=4x10-4] and ETV6del [0.6(0.075-6.615)% vs 0.32(0.029-3.94)%, p=0.02]. Also median MRD level at day 33 was elevated in patients with BCR-ABL1 fusion [0.03(0.0001-0.08)% vs 1x10-4(0.0001-0.005)%, p=0.02] and in patients with IKZF1 deletion [1x10-4(0.0001-0.05)% vs 1x10-4(0.0001-0.003)%, p=0.02]. Multivariate analysis of MRD15, MRD33 and ΔMRD was done for variables with univariate significance of p<0.15 (log10WBC, age at diagnosis, sex, poor steroid response, hypodiploidy, MLL rearrangements, BCR-ABL1 fusion, IKZF1 del, ETV6 del, EBF1 del, PAR1 del). A mixed effects model was used to evaluate intraindividual changes of MRD15 and MRD33 and factored in genetic covariates. The following variables were significant for MRD15 and MRD33 timepoints: log10WBC (β=0.28, p=1x10-7) and (β=0.09, p=0.05), age at diagnosis (β=0.22, p=1x10-7) and (β=0.23, p=1x10-6), IKZF1 del (β=0.14, p=1x10-3) and (β=0.08, p=0.08), respectively. Additionally the following variables were significantly associated with the absolute difference of MRD between MRD33 and MRD15: logWBC (β=-0.15, p=4x10-4), steroid resistance (β=-0.38, p=1x10-6), IKZF1 del (β=-0.19, p=2x10-2), and PAR1 del (β=-0.13, p=3x10-3). MTT confirmed increased resistance to asparaginase of IKZF1 del positive blasts (p=0.01).
Conclusion
Poorer blast clearance during induction protocol in ALL patients harboring IKZF1 deletions may result partly from chemoresistance to L-ASP, which was noted for the first time in both clinical and in vitro settings.
Session topic: E-poster
Keyword(s): Acute lymphoblastic leukemia, Gene deletion, Minimal residual disease (MRD)
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