|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Prepublished online as a Blood First Edition Paper on May 17, 2002; DOI 10.1182/blood-2002-02-0495.
CLINICAL OBSERVATIONS, INTERVENTIONS, AND THERAPEUTIC TRIALS
From the Department of Pharmaceutical Sciences,
Department of Biostatistics, Department of Hematology-Oncology, and
Department of Pathology, St Jude Children's Research Hospital; and
University of Tennessee; both of Memphis, TN.
Methotrexate (MTX) and mercaptopurine (MP) are widely used
antileukemic agents that inhibit de novo purine synthesis (DNPS) as a
mechanism of their antileukemic effects. To elucidate pharmacodynamic differences among children with acute lymphoblastic leukemia (ALL), DNPS was measured in leukemic blasts from newly diagnosed patients before and after therapy with these agents. Patients were randomized to
receive low-dose MTX (LDMTX: 6 oral doses of 30 mg/m2) or
high-dose MTX (HDMTX: intravenous 1 g/m2) followed by
intravenous MP; or intravenous MP alone (1 g/m2), as
initial therapy. At diagnosis, the rate of DNPS in bone marrow leukemia
cells was 3-fold higher in patients with T-lineage ALL compared
with those with B-lineage ALL (769 ± 189 vs 250 ± 38 fmol/nmol/h;
P = .001). DNPS was not consistently inhibited following
MP alone but was markedly inhibited following MTX plus MP (median
decrease 3% vs 94%; P < .001). LDMTX plus MP and HDMTX plus MP produced greater antileukemic effects (percentage decrease in
circulating leukocyte counts) compared with MP alone ( Methotrexate (MTX) and mercaptopurine (MP) are
antimetabolites that form the cornerstone of continuation therapy for
childhood acute lymphoblastic leukemia (ALL).1 Both of
these agents can inhibit de novo purine synthesis (DNPS), which is
postulated as a mechanism of their antileukemic effects and a rationale
for using them in combination.2 MTX is converted by
folylpolyglutamate synthase to methotrexate polyglutamates
(MTXPGs).3 MTXPGs inhibit dihydrofolate reductase, thereby
decreasing the amount of reduced folates, the one-carbon donor for the
purine ring formation in DNPS,3 and MTXPGs also directly
inhibit phosphoribosylpyrophosphate (PRPP)
amidotransferase,4 glycinamide ribonucleotide (GAR) transformylase, and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase,5 key enzymes in the DNPS pathway.
MP is metabolized by the purine salvage enzyme, hypoxanthine-guanine phosphoribosyltransferase, to thioinosine monophosphate and
subsequently metabolized to thioguanine nucleotides or alternatively
metabolized by thiopurine methyltransferase to methylthioinosine
monophosphate, an inhibitor of PRPP amidotransferase.6,7
The consequence of DNPS inhibition by these antimetabolites is purine
deprivation, leading to inhibition of DNA synthesis, decreased cell
proliferation, and cytotoxicity.8
Although in vitro studies have demonstrated that DNPS inhibition by MTX
and/or MP contributes to their cytotoxic effects6,8 and
that MTX putatively acts synergistically with MP by enhancing the
accumulation of PRPP, a necessary cofactor for MP
activation,9,10 these mechanisms have not been established
in primary leukemia cells in vivo.
In the present investigation, we determined the effects of a single
dose of MP alone or in combination with low-dose or high-dose MTX on
DNPS in bone marrow leukemia cells from patients with newly diagnosed
ALL. These studies revealed significant lineage differences in DNPS
rates at diagnosis of ALL and a significant relation between the extent
of DNPS inhibition and antileukemic effects of these medications.
Patients and treatment
After stratification for age, leukocyte count, immunophenotype, and
sex, patients were randomized to receive 1 of 3 upfront therapies
(Figure 1): intravenous MP alone
(intravenous MP: 1 g/m2 over 6 hours consisting of 200 mg/m2 over 20 minutes and 800 mg/m2 over 5 hours 40 minutes); low-dose oral MTX (LDMTX: 30 mg/m2 every
6 hours for a total of 6 doses) followed by intravenous MP (same dose
as above); or high-dose intravenous MTX (HDMTX: 1 g/m2 over
24 hours consisting of 200 mg/m2 intravenous push and 800 mg/m2 over 24 hours) immediately followed by intravenous MP
(same as above). Intravenous MTX and oral MTX were purchased from
Lederle Laboratories (Pearl River, NY). Intravenous MP was supplied by the National Cancer Institute, as a lyophilized powder of sodium salt
of MP (0.5 mg per vial). MP salt was reconstituted with sterile water
for injection. Patients received hydration with intravenous dextrose
5%/0.25 normal saline with 40 mEq NaHCO3 per liter.
NaHCO3 was given as needed to maintain urine pH at least
6.5 but less than 8.0. All patients treated with MTX received
leucovorin rescue (10 mg/m2 orally or intravenously every 6 hours for 5 doses starting 48 hours from the start of MTX). Leucovorin
rescue was continued until the plasma MTX concentration was below 0.1 µM.
To prevent or treat hyperuricemia and tumor lysis syndrome, urate
oxidase13 (Uricozyme; Sanofi-Synthelabo, Paris, France) or
its recombinant analog (Rasburicase; Sanofi-Synthelabo) was administered intravenously if required. In case of contraindication to
Uricozyme and Rasburicase (glucose 6-phosphate dehydrogenase deficiency, asthma, and history of atopic allergy), allopurinol (Zyloprim; Glaxo-Wellcome, Research Triangle Parks, NJ) was given orally.
Bone marrow collection and processing
Evaluation of response to chemotherapy Circulating leukocyte counts were measured before therapy (day 0) and at day 3, prior to the administration of other antileukemic agents. Leukocyte counts were determined with a Coulter counter (model F+STKR; Coulter, Hialeah, FL). The percentage change in leukocyte count 3 days after beginning chemotherapy was determined as the day 3 count minus the day 0 count, divided by the day 0 count, and multiplied by 100.Determination of bone marrow purine bases, rate of DNPS, and MTXPG concentrations The concentration of purine bases from hydrolyzed nucleotides and the rate of DNPS in ALL blasts were simultaneously determined by quantifying unlabeled and radiolabeled purine bases (adenine and guanine) after acid hydrolysis of a 2-hour ex vivo incubation of 5 × 106 lymphoblasts with 14C-formate, as previously described.14,15 The concentrations of unlabeled adenine and guanine were determined from peak areas of UV chromatograms against a linear calibration curve of standards (1-75 nmol on column) prepared in phosphate-buffered saline. Newly synthesized purines were determined by the concentration of 14C-adenine and 14C-guanine, which were calculated on the basis of the total disintegrations per minute (dpm) corresponding to the relevant peaks of the chromatograms, with a specific activity of 50 dpm/pmol. The detection limit for the radiolabeled purines was 0.02 pmol on column. The rate of de novo adenine plus guanine synthesis (DNPS) was calculated as the femtomoles of newly synthesized adenine plus guanine per nanomole of total intracellular adenine plus guanine per hour of incubation (fmol/nmol/h). Under conditions used, the rate of DNPS (14C incorporation from formate) remained linear for incubation times of 30 to 120 minutes in human CEM-CCRF (ATCC, Manassas, VA) leukemia cells (linear correlation coefficient 0.986 ± 0.009, mean of 3 experiments). Similarly, the rate of de novo adenine or de novo guanine synthesis was calculated as the femtomoles of newly synthesized adenine or guanine per nanomole of total intracellular adenine plus guanine per hour of incubation. The percentage change in DNPS 20 hours after initiation of MP was determined by comparison with the initial DNPS (subtraction of the 20 hours of DNPS from the pretherapy DNPS, dividing by the pretherapy DNPS, and multiplying by 100). Intracellular purine concentrations are expressed as nanomoles per 106 cells. Inhibition of DNPS was classified as full (> 90%), partial (10%-89%), or no (< 10%) inhibition. The high-performance liquid chromatography separation and measurement of MTX and 6 polyglutamated metabolites (MTXPG2 to MTXPG7) were performed as previously described.16Statistical analyses The distributions of sex, immunophenotypes, ploidy, type of uricolytic therapy received in the 72 hours preceding key time points (bone marrow aspirates at diagnosis and after chemotherapy), as well as the patterns of DNPS inhibition were assessed with either the 2 or exact 2 test as appropriate.
Quantitative variables and demographic characteristics were compared
among the 3 treatment arms with the exact Kruskal-Wallis test or
compared with the exact Wilcoxon rank sum test17 when only
2 treatment groups were considered. Change between any 2 time points
was assessed with the exact Wilcoxon signed rank test. No adjustments
have been made for multiple testing. Results are expressed as mean ± SE unless otherwise indicated.
Patients Between August 1994 and July 1998, 233 children with newly diagnosed ALL were enrolled on the St Jude Total Therapy XIIIB protocol and randomized to receive 1 of 3 initial treatments: MP alone (76 patients), LDMTX plus MP (83 patients), or HDMTX plus MP (74 patients). There were no significant differences in demographic characteristics (Table 1) or the frequency of uricolytics administered among the 3 groups of patients or between patients randomized to MP alone versus MTX plus MP.
Effect of chemotherapy among treatment regimens and immunophenotypes At initiation of chemotherapy, leukocyte counts were similar among the 3 treatment groups (P = .83; n = 233), whereas within each treatment arm patients presenting with T-lineage ALL had higher leukocyte counts than those with B-lineage ALL (P < .001). As depicted in Figure 2A, patients with nonhyperdiploid B-lineage ALL presented with higher leukocyte counts than those with hyperdiploid B-lineage ALL (P < .001).
Antileukemic response was evaluable in 195 patients (38 were not
evaluable because leukocyte count was not determined on day 3) based on
the decrease in circulating leukocytes over the initial 3 days of
treatment. As depicted in Figure 2B, the average percentage decrease in
leukocyte counts was significantly less in patients randomized to MP
alone ( In patients randomized to MP alone, a similar percentage decrease
in leukocyte counts was observed among the 3 leukemic subtypes (P = .137) (Figure 2B). In patients who received MTX (high
dose or low dose) plus MP, those with T-lineage ALL had a greater
percentage decrease in leukocyte counts ( DNPS and intracellular purine concentrations At diagnosis, bone marrow DNPS rates and intracellular purine concentrations were evaluable in 194 patients (40 were not evaluable because of poor yields of the bone marrow aspirate). No significant effect of uricolytics (within 72 hours prior to the bone marrow aspirate) was observed on de novo adenine, guanine, or adenine plus guanine synthesis rates (P > .20). De novo adenine, guanine, and de novo adenine plus guanine synthesis rates were higher in T-lineage ALL (n = 32) than B-lineage ALL (n = 161), with no difference between hyperdiploid B-lineage ALL (n = 55) and nonhyperdiploid B-lineage ALL (n = 106) (P > .60) (Figure 3A). Patients with T-lineage ALL had on average 4-fold and 2-fold higher de novo adenine and de novo guanine synthesis rates when compared with B-lineage ALL (P = .0007 and P = .010 respectively), resulting in a 3-fold higher total DNPS rate (adenine plus guanine) in T-lineage ALL compared with B-lineage ALL (769 ± 189 vs 250 ± 38 fmol/nmol/h; P = .001) (Figure 3A).
Bone marrow hypoxanthine plus inosine concentrations were higher in hyperdiploid B-lineage ALL (1.10 ± 0.29 nmol/106 cells, n = 42) than in nonhyperdiploid B-lineage ALL (0.65 ± 0.12 nmol/106 cells, n = 93) and higher in hyperdiploid B-lineage ALL than T-lineage ALL (0.41 ± 0.20 nmol/106 cells, n = 27) (P < .001). Furthermore, adenine concentrations were higher in hyperdiploid B-lineage ALL (5.10 ± 0.37 nmol/106 cells, n = 51) than in nonhyperdiploid B-lineage ALL (4.16 ± 0.26 nmol/106 cells, n = 99) and higher than in nonhyperdiploid B-lineage ALL compared with T-lineage ALL (3.64 ± 0.24 nmol/106 cells, n = 27) (P = .007). However, intracellular guanine concentrations were similar among the 3 leukemic subtypes (P = .52) (Figure 3B). Effect of treatment regimens on DNPS The change in DNPS rate from initiation of chemotherapy to 20 or 44 hours after chemotherapy was evaluable in 158 patients (51 patients randomized to MP, 62 patients to LDMTX plus MP, and 45 to HDMTX plus MP). The remaining 75 patients were not evaluated because there were insufficient cells to measure DNPS at diagnosis or after treatment. In patients randomized to MP alone, there was no significant inhibition of DNPS rate at 20 hours (median change of 3%, n = 51;
P = .34). In contrast, as depicted in Figure 4A, there was inhibition of DNPS in
patients randomized to receive LDMTX plus MP (median change of 94%,
n = 62; P < .001) or HDMTX plus MP (median change of
99%, n = 45; P < .001). These differences were
similar when either de novo adenine or de novo guanine synthesis rates
were compared (not shown).
Patients with hyperdiploid B-lineage ALL exhibited less inhibition of
DNPS (median change of Among 158 evaluable patients, full DNPS inhibition occurred in 78 patients (49%), partial inhibition in 47 patients (30%), and no inhibition in 33 patients (21%). The percentage of patients having full DNPS inhibition was significantly lower after MP alone (20%) compared with LDMTX plus MP (53%; P < .001) or HDMTX plus MP treatment (78%; P < .001). Furthermore, full DNPS inhibition was achieved in a higher percentage of patients randomized to HDMTX plus MP compared with LDMTX plus MP (P = .027) (Figure 4B). Effects of MTXPGs on DNPS In 106 patients treated with MTX plus MP, MTXPG concentrations were measured in leukemia cells from bone marrow aspirates obtained 44 hours after the start of MTX treatment. Patients randomized to HDMTX plus MP had on average 2-fold higher MTXPG concentrations (MTXPG1-7: 2148 ± 298 pmol/109 cells, n = 47) than those randomized to LDMTX plus MP (1075 ± 114 pmol/109 cells, n = 59) (P = .0027). Similarly, HDMTX plus MP treatment produced 1.7-fold higher long-chain MTXPG concentrations (MTXPG4-7: 1316 ± 159 pmol/109 cells, n = 47) compared with LDMTX plus MP (818 ± 88 pmol/109 cells, n = 59) (P = .0141).As depicted in Figure 5A, patients with
T-lineage ALL had significantly lower MTXPG1-7
concentrations (691 ± 146 pmol/109 cells, n = 23) than
patients with nonhyperdiploid B-lineage ALL (1467 ± 161
pmol/109 cells, n = 61; P < .001), and
patients with nonhyperdiploid B-lineage ALL had lower
MTXPG1-7 concentrations than those with hyperdiploid B-lineage ALL (2684 ± 499 pmol/109 cells, n = 22;
P = .001). Similar results were observed when long-chain
MTXPG4-7 concentrations were compared (Figure 5B) or when
lineage and ploidy were assessed within the LDMTX plus MP or the HDMTX
plus MP groups. The administration of HDMTX plus MP resulted in
2.1-fold higher MTXPG1-7 concentrations compared with LDMTX
plus MP administration in patients with hyperdiploid B-lineage ALL
(4033 ± 1005 pmol/109 cells, n = 9, vs 1751 ± 308
pmol/109 cells, n = 13; P < .01) or
nonhyperdiploid B-lineage ALL (2043 ± 284 pmol/109
cells, n = 28, vs 978 ± 127 pmol/109 cells, n = 33;
P < .01). However, in patients with T-lineage ALL, the
administration of HDMTX plus MP did not produce higher MTXPG1-7 concentrations when compared with LDMTX plus MP
(749 ± 274 pmol/109 cells, n = 10, vs 646 ± 161
pmol/109 cells, n = 13, respectively;
P = .49) (Figure 5A).
There were significantly higher MTXPG1-7 concentrations in leukemia cells of patients with full inhibition of DNPS (1803 ± 236 pmol/109 cells, n = 52) compared with patients with partial or no inhibition (939 ± 124 pmol/109 cells, n = 31) (P = .0172) (Figure 5C). Similar results were observed when only patients with hyperdiploid or nonhyperdiploid B-lineage ALL were considered (P < .025); however, within patients with T-lineage ALL there was not a statistically significant difference, although the trend was similar (P = .35) (Figure 5C). Significantly lower MTXPG1-7 concentrations were required for full DNPS inhibition in patients with T-lineage ALL (831 ± 215 pmol/109 cells, n = 14) compared with those with nonhyperdiploid B-lineage ALL (1845 ± 303 pmol/109 cells, n = 28) or hyperdiploid B-lineage ALL (3044 ± 674 pmol/109 cells, n = 10) (P = .001). Similar differences were observed with long-chain MTXPG4-7 (Figure 5D) or when the analysis was restricted to the LDMTX plus MP or the HDMTX plus MP group (data not shown). Effect of treatment regimen on DNPS and relationship to response to chemotherapy Among the 158 patients with evaluable DNPS inhibition, 135 (85%) were also evaluable for initial response to chemotherapy. As depicted in Figure 6A, full DNPS inhibition was associated with a significantly greater percentage decrease in circulating leukocytes (57% ± 4%, n = 71) compared with
partial inhibition (38% ± 7%, n = 38; P = .008)
or no inhibition (29% ± 6%, n = 26; P < .001).
However, there was no significant difference in the percentage decrease
in circulating leukocytes between patients having partial or no
inhibition (P = .11). Therefore, these 2 groups (47% of
patients) were combined and compared with the group of patients (53%)
having full DNPS inhibition.
In patients with nonhyperdiploid B-lineage ALL or T-lineage ALL, those
having full inhibition of DNPS had a greater percentage decrease in
circulating leukocytes compared with those with partial or no
inhibition (B-lineage: Within patients randomized to MTX plus MP, those with hyperdiploid
B-lineage ALL did not exhibit a significantly greater percentage decrease in circulating leukocyte counts with full DNPS inhibition versus partial or no inhibition of DNPS ( Within patients with nonhyperdiploid B-lineage or T-lineage ALL
randomized to LDMTX plus MP (n = 42), those with full DNPS inhibition
had a greater percentage decrease in leukocyte counts (
We have investigated in a randomized clinical trial the in vivo antileukemic effects of MP alone or in combination with LDMTX or HDMTX in children with ALL. These 2 agents are among the most widely used medications in the curative therapy of childhood ALL, yet their mechanisms and optimal doses remain to be fully elucidated in different ALL subtypes. Previous studies suggested that high-dose intravenous MP plus HDMTX improves outcome in childhood ALL.18,19 However, the therapeutic effect of high-dose MP alone has not been evaluated. The objective of the current research was to determine whether MP alone or in combination with MTX inhibits DNPS and how this relates to the antileukemic effects of these medications. Purine nucleotides are synthesized by the salvage pathway and by the de novo pathway, the latter being specifically measured in the current study. We found that leukemic cells from patients with T-lineage ALL have on average 4-fold and 2-fold higher de novo adenine and de novo guanine synthesis rates at diagnosis, resulting in a 3.0-fold higher total DNPS rate when compared with patients with B-lineage ALL. In addition, patients with T-lineage ALL had lower intracellular concentrations of inosine, hypoxanthine, and adenine but similar guanine concentrations compared with those with B-lineage ALL. These new findings are consistent with prior studies reporting constitutive differences in purine enzyme activities in T-lineage ALL compared with B-lineage ALL.20,21 Therefore, T-lineage ALL may be more dependent on the de novo pathway for purine synthesis (especially adenine) compared with B-lineage ALL, a finding consistent with previous in vitro data in cell lines9 and with recent evidence22-24 that methylthioadenosine phosphorylase (an adenine salvage gene) is more frequently deleted in T-lineage than in B-lineage ALL, because of its close genomic proximity to the tumor suppressors P16INK4A/P15INK4B. In addition, hypoxanthine inhibits DNPS by feedback mechanisms,25,26 and the lower intracellular hypoxanthine plus inosine concentrations in T-lineage ALL compared with B-lineage ALL suggest that lower purine recycling and salvage activity may be compensated for by increased DNPS in T-lineage ALL. In vitro, MTX produces DNPS inhibition through folate depletion as well as direct inhibition by MTXPGs of key DNPS enzymes, amidophosphoribosyltransferase, AICAR, and GAR transformylases.3-5 In contrast, MP is known to inhibit DNPS only through inhibition of amidophosphoribosyltransferase by methylthioinosine nucleotides.7 Our data establish that a single high-dose of MP does not consistently inhibit DNPS in ALL cells in vivo, whereas the combination of MTX and MP does. It is unclear whether inhibition of DNPS is due predominantly to MTX, but this is likely because MP had little effect alone and HDMTX produced greater inhibition than LDMTX. In this regard, our data support the use of HDMTX in childhood ALL, to more consistently achieve full DNPS inhibition, compared with LDMTX, because full DNPS inhibition produced greater antileukemic effects compared with partial or no inhibition. Partial DNPS inhibition was not associated with significantly greater antileukemic effects when compared with no DNPS inhibition, suggesting that full DNPS inhibition is required to trigger cell death. This is consistent with the notion that leukemia cells rely more on the de novo pathway than on salvage mechanisms to synthesize purines and that near complete inhibition of purine synthesis may be required to produce a purineless state, leading to cell death. However, DNPS inhibition is only one mechanism of action shared by MTX and MP, and a component of the antileukemic effects of these 2 agents may be mediated via alternative mechanisms, such as inhibition of thymidylate synthase by MTXPGs or incorporation of deoxythioguanosine into DNA following MP. MTXPGs inhibit other targets in a concentration-dependent manner, and the current work further establishes that HDMTX achieves higher MTXPGs concentrations in ALL blasts in vivo compared with LDMTX. Interestingly, the relationship of DNPS inhibition to antileukemic effect was dissimilar among leukemic subtypes. In patients with nonhyperdiploid B-lineage and T-lineage ALL, full DNPS inhibition produced greater antileukemic effects than partial or no inhibition, whereas in patients with hyperdiploid B-lineage ALL, no relationship was evident between the extent of DNPS inhibition and antileukemic response. This suggests that DNPS inhibition may be a more important mechanism for antileukemic effects in patients with nonhyperdiploid B-lineage or T-lineage ALL than hyperdiploid B-lineage ALL. Unexpectedly, patients with T-lineage ALL had a greater decrease in circulating leukocytes than those with B-lineage ALL following MTX. It is plausible that T-lineage ALL is more susceptible to DNPS inhibition than B-lineage ALL, because T-ALL blasts rely more on DNPS than on the purine salvage pathway.24,27-29 In contrast, more efficient purine salvage or purine recycling mechanisms in hyperdiploid B-lineage (consistent with greater hypoxanthine and inosine concentrations at diagnosis) may explain their lower sensitivity to DNPS inhibition compared with nonhyperdiploid B-lineage ALL. A good initial response during the first week of chemotherapy has been associated with a good overall treatment outcome in patients with ALL (ie, response to steroids).30 In that regard, results in the present study appear paradoxical, because patients with hyperdiploid B-lineage ALL exhibited lower initial response to chemotherapy compared with patients with T-lineage ALL, yet, overall, patients with hyperdiploid B-lineage ALL have a better event-free survival than most other ALL subtypes. However, it is possible that the initial decrease in leukocyte counts following MTX and MP (over 72 hours in our study) does not have the same prognostic value as the steroid response over 7 days.30 In addition, the improved event-free survival in patients with hyperdiploid B-lineage ALL compared with patients with T-lineage ALL might reflect their sensitivity to other chemotherapeutic agents given during 2.5 to 3 years of therapy (eg, L-asparaginase and cytarabine).31 In the LDMTX plus MP group, patients with nonhyperdiploid B-lineage or T-lineage ALL had greater antileukemic response when full DNPS inhibition was achieved. In contrast, within the HDMTX plus MP treatment group, the antileukemic response did not differ in patients with full versus partial or no DNPS inhibition. In addition, among patients with nonhyperdiploid B-lineage ALL, HDMTX plus MP produced a greater percentage decrease in leukocyte counts than LDMTX plus MP in patients with partial or no inhibition of DNPS, and similar differences were observed between the 2 MTX arms in case of full inhibition. Taken together, these findings support the rationale for HDMTX in childhood ALL, because HDMTX plus MP is more likely to produce complete DNPS inhibition and because HDMTX plus MP produces greater antileukemic effects in the absence of complete DNPS inhibition, consistent with additional mechanisms of action for HDMTX versus LDMTX. Going forward, it will be important to determine the optimal dosage and schedule of HDMTX in the major lineage and genetic subtypes of childhood ALL to maximize the efficacy of this widely used antileukemic agent.
We thank our clinical staff for scrupulous attention to patient care and management of blood sampling; our research nurses, Sheri Ring, Lisa Walters, and Terri Kuehner; and the patients and their parents for their participation in this study. We also thank Eve Su, YaQin Chu, May Chung, Kathryn Brown, Margaret Needham, Emily Melton, and Anatoli Lenchik for technical assistance and Nancy Kornegay for her computer and database expertise.
Submitted February 14, 2002; accepted April 9, 2002.
Prepublished online as Blood First Edition Paper, May 17, 2002; DOI 10.1182/blood-2002-02-0495.
Supported by grants CA 36401, CA 78224, CA21765, and CA51001 from the National Institutes of Health; a Center of Excellence grant from the State of Tennessee; and American Lebanese Syrian Associated Charities.
T.D. and T.L.B. contributed equally to this work.
The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734.
Reprints: William E. Evans, Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, 332 N Lauderdale, Memphis, TN 38105; e-mail: william.evans{at}stjude.org.
1.
Pui CH, Evans WE.
Acute lymphoblastic leukemia.
N Engl J Med.
1998;339:605-615 2. Chu E, Johnston PG, Grem JL, et al. Antimetabolites. Cancer Chemother Biol Response Modif. 1994;15:1-31[Medline] [Order article via Infotrieve]. 3. Chabner BA, Allegra CJ, Curt GA, et al. Polyglutamation of methotrexate. Is methotrexate a prodrug? J Clin Invest. 1985;76:907-912[Medline] [Order article via Infotrieve]. 4. Fairbanks LD, Ruckemann K, Qiu Y, et al. Methotrexate inhibits the first committed step of purine biosynthesis in mitogen-stimulated human T-lymphocytes: a metabolic basis for efficacy in rheumatoid arthritis? Biochem J. 1999;342:143-152.
5.
Allegra CJ, Drake JC, Jolivet J, Chabner BA.
Inhibition of phosphoribosylaminoimidazolecarboxamide transformylase by methotrexate and dihydrofolic acid polyglutamates.
Proc Natl Acad Sci U S A.
1985;82:4881-4885
6.
Dervieux T, Blanco JG, Krynetski EY, et al.
Differing contribution of thiopurine methyltransferase to mercaptopurine versus thioguanine effects in human leukemic cells.
Cancer Res.
2001;61:5810-5816 7. Tay BS, Lilley RM, Murray AW, Atkinson MR. Inhibition of phosphoribosyl pyrophosphate amidotransferase for Erlich ascites-tumour cells by thiopurine nucleotides. Biochem Pharmacol. 1969;18:936-938[CrossRef][Medline] [Order article via Infotrieve]. 8. Bokkerink JP, De Abreu RA, Bakker MA, et al. Effects of methotrexate on purine and pyrimidine metabolism and cell-kinetic parameters in human malignant lymphoblasts of different lineages. Biochem Pharmacol. 1988;37:2329-2338[CrossRef][Medline] [Order article via Infotrieve]. 9. Bokkerink JP, Bakker MA, Hulscher TW, De Abreu RA, Schretlen ED. Purine de novo synthesis as the basis of synergism of methotrexate and 6-mercaptopurine in human malignant lymphoblasts of different lineages. Biochem Pharmacol. 1988;37:2321-2327[CrossRef][Medline] [Order article via Infotrieve]. 10. Bokkerink JP, Bakker MA, Hulscher TW, et al. Sequence-, time- and dose-dependent synergism of methotrexate and 6-mercaptopurine in malignant human T-lymphoblasts. Biochem Pharmacol. 1986;35:3549-3555[CrossRef][Medline] [Order article via Infotrieve].
11.
Pui C-H, Crist WM, Look AT.
Biology and clinical significance of cytogenetic abnormalities in childhood acute lymphoblastic leukemia.
Blood.
1990;76:1449-1463
12.
Look AT, Melvin SL, Williams DL, et al.
Aneuploidy and percentage of S-phase cells determined by flow cytometry correlate with cell phenotype in childhood acute leukemia.
Blood.
1982;60:959-967
13.
Pui CH, Mahmoud HH, Wiley JM, et al.
Recombinant urate oxidase for the prophylaxis or treatment of hyperuricemia in patients with leukemia or lymphoma.
J Clin Oncol.
2001;19:697-704 14. Masson E, Relling MV, Synold TW, et al. Accumulation of methotrexate polyglutamates in lymphoblasts is a determinant of antileukemic effects in vivo. A rationale for high-dose methotrexate. J Clin Invest. 1996;97:73-80[Medline] [Order article via Infotrieve]. 15. Masson E, Synold TW, Relling MV, et al. Allopurinol inhibits de novo purine synthesis in lymphoblasts of children with acute lymphoblastic leukemia. Leukemia. 1996;10:56-60[Medline] [Order article via Infotrieve]. 16. Synold TW, Relling MV, Boyett JM, et al. Blast cell methotrexate-polyglutamate accumulation in vivo differs by lineage, ploidy, and methotrexate dose in acute lymphoblastic leukemia. J Clin Invest. 1994;94:1996-2001[Medline] [Order article via Infotrieve]. 17. Proc-StatXact for SAS users: statistical software for exact non parametric inference. Cambridge, MA: Cytel; 1997. 18. Mahoney DH Jr, Camitta BM, Leventhal BG, et al. Repetitive low dose oral methotrexate and intravenous mercaptopurine treatment for patients with lower risk B-lineage acute lymphoblastic leukemia. A Pediatric Oncology Group pilot study. Cancer. 1995;75:2623-2631[CrossRef][Medline] [Order article via Infotrieve]. 19. Camitta B, Mahoney D, Leventhal B, et al. Intensive intravenous methotrexate and mercaptopurine treatment of higher-risk non-T, non-B acute lymphocytic leukemia: a Pediatric Oncology Group study. J Clin Oncol. 1994;12:1383-1389[Abstract]. 20. van Laarhoven JP, De Bruyn CH. Purine metabolism in relation to leukemia and lymphoid cell differentiation. Leuk Res. 1983;7:451-480[CrossRef][Medline] [Order article via Infotrieve].
21.
Poplack DG, Blatt J, Reaman G.
Purine pathway enzyme abnormalities in acute lymphoblastic leukemia.
Cancer Res.
1981;41:4821-4823 22. Rubnitz JE, Behm FG, Pui CH, et al. Genetic studies of childhood acute lymphoblastic leukemia with emphasis on p16, MLL, and ETV6 gene abnormalities: results of St Jude Total Therapy Study XII. Leukemia. 1997;11:1201-1206[CrossRef][Medline] [Order article via Infotrieve].
23.
Hebert J, Cayuela JM, Berkeley J, Sigaux F.
Candidate tumor-suppressor genes MTS1 (p16INK4A) and MTS2 (p15INK4B) display frequent homozygous deletions in primary cells from T- but not from B-cell lineage acute lymphoblastic leukemias.
Blood.
1994;84:4038-4044
24.
Batova A, Diccianni MB, Nobori T, et al.
Frequent deletion in the methylthioadenosine phosphorylase gene in T-cell acute lymphoblastic leukemia: strategies for enzyme-targeted therapy.
Blood.
1996;88:3083-3090 25. King ME, Honeysett JM, Howell SB. Regulation of de novo purine synthesis in human bone marrow mononuclear cells by hypoxanthine. J Clin Invest. 1983;72:965-970[Medline] [Order article via Infotrieve].
26.
Yamaoka T, Yano M, Kondo M, et al.
Feedback inhibition of amidophosphoribosyltransferase regulates the rate of cell growth via purine nucleotide, DNA, and protein syntheses.
J Biol Chem.
2001;276:21285-21291
27.
Chen ZH, Olopade OI, Savarese TM.
Expression of methylthioadenosine phosphorylase cDNA in p16-, MTAP- malignant cells: restoration of methylthioadenosine phosphorylase-dependent salvage pathways and alterations of sensitivity to inhibitors of purine de novo synthesis.
Mol Pharmacol.
1997;52:903-911
28.
Hori H, Tran P, Carrera CJ, et al.
Methylthioadenosine phosphorylase cDNA transfection alters sensitivity to depletion of purine and methionine in A549 lung cancer cells.
Cancer Res.
1996;56:5653-5658 29. Sano H, Kubota M, Kasai Y, et al. Increased methotrexate-induced DNA strand and cytotoxicity following mutational loss of thymidine kinase. Int J Cancer. 1991;48:92-95[Medline] [Order article via Infotrieve].
30.
Reiter A, Schrappe M, Ludwig W-D, et al.
Chemotherapy in 998 unselected acute lymphoblastic leukemia patients. Results and conclusions of the multicenter trial ALL-BFM.
Blood.
1994;84:3122-3133
31.
Kaspers G, Smets L, Pieters R, et al.
Favorable prognosis of hyperdiploid common acute lymphoblastic leukemia may be explained by sensitivity to antimetabolites and other drugs: result of an in vitro study.
Blood.
1995;85:751-756
© 2002 by The American Society of Hematology.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
 |
|
  A. D. ASKANASE, D. J. WALLACE, M. H. WEISMAN, C.-E TSENG, L. BERNSTEIN, H. M. BELMONT, E. SEIDMAN, M. ISHIMORI, P. M. IZMIRLY, and J. P. BUYON Use of Pharmacogenetics, Enzymatic Phenotyping, and Metabolite Monitoring to Guide Treatment with Azathioprine in Patients with Systemic Lupus Erythematosus J Rheumatol, January 1, 2009; 36(1): 89 - 95. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 U Hindorf, M Lindqvist, C Peterson, P Soderkvist, M Strom, H Hjortswang, A Pousette, and S Almer Pharmacogenetics during standardised initiation of thiopurine treatment in inflammatory bowel disease Gut, October 1, 2006; 55(10): 1423 - 1431. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Davies Pharmacogenetics, Pharmacogenomics and Personalized Medicine: Are We There Yet? Hematology, January 1, 2006; 2006(1): 111 - 117. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Zaza, M. Cheok, W. Yang, J. C. Panetta, C.-H. Pui, M. V. Relling, and W. E. Evans Gene expression and thioguanine nucleotide disposition in acute lymphoblastic leukemia after in vivo mercaptopurine treatment Blood, September 1, 2005; 106(5): 1778 - 1785. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.-H. Pui, J. T. Sandlund, D. Pei, D. Campana, G. K. Rivera, R. C. Ribeiro, J. E. Rubnitz, B. I. Razzouk, S. C. Howard, M. M. Hudson, et al. Improved outcome for children with acute lymphoblastic leukemia: results of Total Therapy Study XIIIB at St Jude Children's Research Hospital Blood, November 1, 2004; 104(9): 2690 - 2696. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Zaza, W. Yang, L. Kager, M. Cheok, J. Downing, C.-H. Pui, C. Cheng, M. V. Relling, and W. E. Evans Acute lymphoblastic leukemia with TEL-AML1 fusion has lower expression of genes involved in purine metabolism and lower de novo purine synthesis Blood, September 1, 2004; 104(5): 1435 - 1441. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Kishi, W. Yang, B. Boureau, S. Morand, S. Das, P. Chen, E. H. Cook, G. L. Rosner, E. Schuetz, C.-H. Pui, et al. Effects of prednisone and genetic polymorphisms on etoposide disposition in children with acute lymphoblastic leukemia Blood, January 1, 2004; 103(1): 67 - 72. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Dervieux, D. Orentas Lein, J. Marcelletti, K. Pischel, K. Smith, M. Walsh, and R. Richerson HPLC Determination of Erythrocyte Methotrexate Polyglutamates after Low-Dose Methotrexate Therapy in Patients with Rheumatoid Arthritis Clin. Chem., October 1, 2003; 49(10): 1632 - 1641. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. V. Relling, J. M. Boyett, J. G. Blanco, S. Raimondi, F. G. Behm, J. T. Sandlund, G. K. Rivera, L. E. Kun, W. E. Evans, and C.-H. Pui Granulocyte colony-stimulating factor and the risk of secondary myeloid malignancy after etoposide treatment Blood, May 15, 2003; 101(10): 3862 - 3867. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 2002 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
Top
Abstract
Introduction
