Patient characteristics
Of 745 patients included in CoALL08-09 89 patients (11.9 %) were allocated to the HR-I treatment arm according to MRD levels at EOI (figure 2). Twelve patients from the HR-I group did not receive AEP (six patients underwent SCT without prior AEP bridging treatment, three patients died before receiving AEP due to a treatment-related morbidity and three patients received other therapy modifications upon physicians’ individual decision).
Fortytwo patients (5.6 %) were classified as failure of remission induction by morphology and confirmed by MRD analysis. Twenty of those did not receive AEP, because SCT was performed prior to AEP (nine patients), treatment-related mortality before AEP (two patients), allergic reaction to amsacrine (one patient) or other therapy modifications according to physicians’ decision (eight patients). One patient had to be excluded from the response analysis in the AEP cohort because of lacking MRD data (figure 2).
The remaining 77 patients in the HR-I group and 22 patients prior to SCT received AEP and were therefore eligible and evaluable for this analysis.
There were 42 high-risk patients from the predecessor trial CoALL07-03 (4.9 % of all patients) with MRD EOI in a comparable range as the HR-I patients, i.e. B-lineage ALL: MRD ≥ 10-3 at day 29 and T-lineage-ALL: MRD ≥ 10-3 at day 29 and day 43. This patient cohort did not receive AEP as part of their consolidation treatment (figure 1) and was used for comparative analysis. The reason for the small proportion of patients with an MRD result in CoALL07-03 is the fact that MRD analysis was not used by default in the first three years of this trial. Due to substantial heterogeneity in treatment approaches we did not perform a comparative analysis of ALL patients with IF including historical control cohorts.
There was an equal distribution of sex and age in the different patient groups. With regard to the molecular genetic features we noted fewerETV6/RUNX1 + translocations among patients in the CoALL08-09 cohort without reaching statistical significance (table 1).