MRD response to AEP
To evaluate the efficacy of AEP treatment in the context of induction
failure we monitored MRD in 21 patients presenting a failure of
remission EOI prior and after AEP. In eight patients (31 %) a profound
MRD reduction of at least half a log-fold was observed. It should be
emphasized here that 5 of these 8 patients had a T-ALL immunophenotype.
The remaining 13 patients (including 7 patients with a T-ALL) did not
discernibly respond to AEP treatment at the molecular level, with no
patient showing a serious increase in disease burden (table 2).
In patients within the HR-I arm MRD assessment was performed after the
consolidation phase at the start of delayed intensification. In 44 of
the 77 HR-I patients that had received AEP MRD results were available.
Of these 44 patients 38 (86%) had no measurable MRD, 2 patients had
discernible but non-quantifiable (n.q.) MRD levels and only 4 patients
still had quantifiable MRD burden. Fifteen of the 77 patients (19%) in
the HR-I cohort who had received AEP suffered from relapsing disease.
Interestingly, only 2 of those relapse-fated 15 patients showed a
positive MRD at the start of delayed intensification, i.e. after AEP,
whereas 7 of them showed negative results indicative of a declining
predictive power of MRD negativity over time of treatment. In 6 patients
who later on relapsed the MRD measurement was not available.