A retrospective chart review of outcomes of favourable risk NPM1 mutated AML patients who underwent allogeneic stem cell transplantation in CR2

Background

NPM1 mutated AML in the absence of FLT3-ITD or adverse karyotype is classified as favourable risk AML according to ELN 2022¹ and these patients are not Allogeneic Stem Cell Transplant (Allo-SCT) candidates in CR1. Typically, the outcomes of those who relapse are also considered to be good with Allo-SCT. We investigated the transplant outcomes of this patient population who have been transplanted in CR2 in our institutional set up.

Methods and Results

We identified 25 patients with NPM1 mutated favorable risk AML at baseline who underwent Allo-SCT in CR2 between January 2015 to December 2022 in our center. Median age of population was 59.5 years (Range 22-72), 13 (52%) were male. All the patients received high dose chemotherapy as first line therapy, most commonly 7+3. The median duration of first complete remission was 15 months (Range 8.3 to 67.7). Two patients were FLT3-ITD at first relapse. Most common second line therapy was high dose chemotherapy (FLAG-IDA), but two received HMA-Ven and two received Gilteritinib. The donor types for Allo-SCT were 8 (32%) MSD ; 13 (52%) MUD and 4(16%) Haplo. Conditioning was myeloablative in 10 (40%). Overall there were 9 (36% ) early deaths at less than d100 of SCT, and median overall survival of the cohort was 35.2 months. There were four post SCT relapses at median day 587 post SCT (range 350 to 735). Median Relapse free survival was 21.2 months. All four post SCT relapse patients could go on to receive a second Allo-SCT and two amongst them are surviving for more than one year post second SCT.

Conclusion

Allo-SCT in CR2 for NPM1 mutated favorable risk AML is an effective treatment option even in the era before NPM1 MRD based decision making for NPM1 mutated AML.