Page 172 - Haematologica April 2020

M. Kroll et al.
analyzed clinical data from DS-ALL and NDS-ALL patients who were treated according to ALL-BFM proto- cols in Germany and Switzerland (ALL-BFM 1995, ALL- BFM 2000 and AIEOP-BFM ALL 2009). We focused on toxicities occurring after HD-MTX administrations during the consolidation element Protocol M in which patients receive four courses of i.v. HD-MTX (5 g/m2 each, 24-hour infusion).
Additionally, we investigated the influence of the rs1051266 80G>A polymorphism of the chromosome 21- encoded folate carrier SLC19A1 (RFC1) on MTX toxicity in DS-ALL. SLC19A1 functions as the main transporter for MTX into cells. Therefore rs1051266 may alter the trans- portation rate of MTX into cells and thus may affect the severity of toxicities.10-12
Methods
Patients
A total of 1,212 patients were selected from three consecutive multicenter ALL-BFM trials (ALL-BFM 95, ALL-BFM 2000 and AIEOP-BFM ALL 2009; diagnosed between January 13, 1996 and September 6, 2016 for DS-ALL and between April 11, 1995 and May 4, 2007 for NDS-ALL patients) according to the following inclusion criteria: age at diagnosis between ≥ 1 year and ≤ 18 years, no initial high risk (HR) features, consolidation treatment with HD-MTX (Protocol M) and availability of treatment and tox- icity data. Detailed information on the different recruitment peri- ods and treatment stratification is given in the Online Supplementary Materials and Methods. Informed consent from the patients and/or guardians was obtained and the studies were approved by the responsible ethical committees.
Consolidation Protocol M is an 8-week therapy element given to non-HR patients only. Patients receive four courses of i.v. HD- MTX (5 g/m2 each, 24-hour infusion) every second week in addi- tion to an age-adapted intrathecal MTX and daily oral 6-MP (25 mg/m2 /day). MTX plasma levels were measured at various time points after the start of each MTX infusion and each HD-MTX course was followed by an i.v. leucovorine (LCV) rescue (15 mg/m2 ) at 42, 48 and 54 hours after the start of the MTX infusion (for details on Protocol M see the Online Supplementary Material and Methods).13 Patients who qualified for the HR group only after the start of Protocol M and who were therefore allocated to the HR treatment arm of the respective study were included in the toxic- ity analysis for the HD-MTX courses they had received (usually only the first course) but not for outcome analysis.
As of 2004, the study group recommended to administer the first HD-MTX course with a reduced dose of 0.5 g/m2 in order to reduce severe toxicities in DS-ALL patients. A subsequent increase of MTX dosages could be performed if no severe toxicity had occurred. After each HD-MTX course, toxicity grading was per- formed for leukopenia, thrombocytopenia, infections, stomatitis, hepatotoxicity, nephrotoxicity and bilirubinemia according to the Common Terminology Criteria for Adverse Events (CTCAE) ver- sion 2.0 (for details see the Online Supplementary Materials and Methods and Online Supplementary Table S1). In some patients reporting was incomplete covering only some of the seven toxici- ties.
Statistical analysis
Statistical analysis included χ2-, Fisher’s exact, Mann-Whitney- U and McNemar tests as indicated in the figure legends and tables. The 5-year-cumulative incidence risk of relapse was calculated according to Kalbfleisch and Prentice and compared using the Gray’s test. Analyses were done using IBM SPSS 22 and SAS 9.4.
A P-value ≤ 0.05 was considered to be statistically significant.
DNA and allelic discrimination assay
Information on patient DNA preparation and SLC19A1 rs1051266 80G>A genotyping can be found in the Online Supplementary Materials and Methods.
Results
Patients, treatment discontinuation and MTX dosages
1,212 patients were included in this study, 103 DS-ALL and 1,109 NDS-ALL. The comparison of both groups showed no significant differences in the median age at diagnosis, sex distribution, and white blood cell counts at diagnosis (Table 1). None of the DS patients had T-cell ALL in contrast to 12.4% of the NDS-ALL group (P=0.006) and a hyperdiploid karyotype was less frequent in DS- ALL compared to NDS-ALL patients (P=0.002). Furthermore, NDS-ALL had more ETV6-RUNX1 rearrangements compared to DS-ALL patients (P<0.001) (Table 1).
Of the 103 DS-ALL patients who started HD-MTX con- solidation 95 patients (92.2%) completed the protocol. Seven DS-ALL patients discontinued consolidation treat- ment at various time points due to a switch to HR treat- ment (n= 4) or severe infections (n= 2). Analysis could not be performed in one patient with DS-ALL for the fourth HD-MTX course due to incomplete toxicity data. One DS-ALL patient died after the second course from septic shock in neutropenia after receiving 5 g/m2 MTX doses in the first and second course. In contrast, 1,083 of 1,109 NDS-ALL patients (97.7%) completed consolidation. Consolidation discontinuation in 26 NDS-ALL patients was due to a switch to HR treatment (n=24) or severe tox- icities (neurotoxicity, n=1 and severe infection, n=1). Three additional patients could not be analyzed due to incomplete data. None of the NDS-ALL patients died dur- ing HD-MTX consolidation (Figure 1).
As of 2004, the ALL-BFM study group recommended for DS-ALL patients to administer a reduced MTX dose of 0.5 g/m2 in the first HD-MTX course and to subsequently increase the dose if no severe side effects occur. Therefore, 51 of 103 (49.5%) DS-ALL patients received the first HD- MTX course with a dose of 0.5 g/m2 (±10%) and 45 of 103 (43.7%) received 5 g/m2 (±10%) in the first course (Table 1). Of note, in some DS-ALL patients a MTX dose of 0.5 g/m2 was given already before 2004 and some DS-ALL patients still received 5 g/m2 doses after the 2004 recom- mendation, (DS-ALL with 0.5 g/m2 MTX in the first course before 2004, n= 6 of 42 [14.3%] and 5.0 g/m2 in first course since 2004, n=11 of 61 [18.0%]).
In contrast, 1,089 of 1,109 (98.2%) non-DS-ALL patients received 5 g/m2 MTX. As expected, the MTX dosages in the course of the consolidation treatment were more het- erogeneous in DS-ALL as compared to NDS-ALL (Table 1).
Toxicities after HD-MTX
Initially we focused on toxicities after the first HD-MTX course because latter courses might be more biased by toxicities and MTX dosages from previous HD-MTX courses, especially in those patients for whom the dose has been adopted after the recommendation in 2004. After receiving a MTX dose of 5 g/m2 patients with DS-ALL showed significantly higher rates of grade 3/4 leukopenia, thrombocytopenia, infections and stomatitis compared to
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