Post-transplant MRD Monitoring by TP53 Duplex Sequencing with APR-246 + Azacitidine Maintenance Predicts Outcomes

Outcomes are poor for TP53 mutant myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) patients who undergo allo-HSCT. Notably, minimal data exist on the impact of TP53 MRD monitoring post allo-HSCT. Thus, we completed duplex TP53 MRD sequencing for all patients on our prospective eprenetapopt (APR-246) + azacitidine maintenance study (n=14). Bone marrow aspirates were obtained prior to allo-HSCT, prior to the start of investigational therapy (day +30 to day +100) and after cycle 3 and cycle 12 of therapy. To assess low allele frequency mutations in TP53, a custom-targeted sequencing panel was used with duplex sequencing, targeting 30,000-70,000X duplex coverage to detect variants at a frequency as low as .005%. For all analyses, TP53 MRD negativity cutoff was 0.01%. All study patients had significant TP53 positivity prior to allo-HSCT and 57% post-HSCT. MRD evaluation after end of maintenance (12 cycles) was the strongest predictor of outcomes. Specifically, MRD negativity after cycle 12 strongly predicted OS (33.9 vs 20.4 months; P=.005) and EFS (33.9 vs 10.1 months; P=.004) with a trend for RFS (32.6 vs 13.5 months; P=.06). TP53 MRD was strongly predictive of outcomes, supporting incorporation of this assay in future novel strategies.