Although azacitidine monotherapy improves survival in myelodysplastic (MDS) patients, various outcomes have been found regarding cytogenetic and molecular features.

This retrospective analysis of 80 Thai patients with MDS treated with azacitidine monotherapy evaluated real-world outcomes in Thailand and identified clinical parameters associated with treatment response and survival. Azacitidine was given at 100 mg/day for 7 days, every 28-day cycle. Targeted exome analysis of 25 genes was performed, using a QIAact Myeloid DNA UMI Panel with GeneReader next generation sequencing system.

MDS with increased blasts (IB) and low blasts (LB) were observed in 64% and 20%, respectively. The median number of cycles of azacitidine therapy was 11 cycles. The ORR was 59%, patients with MDS-IB2 had the highest ORR (71%) compared to those with MDS-IB1 (47%) or MDS-LB (41%), p = 0.029. A significantly lower ORR was found for MDS patients (27%) with complex karyotypes (CKs), p = 0.016. MDS patients with poor/very poor risk cytogenetics had significantly lower ORR than those without poor/very poor risk cytogenesis 37% versus 65%, p = 0.039. MDS patients with mutated TET2 had lower ORR than those with wild-type TET2, 17% vs. 62% (p = 0.041). The median OS in patients with MDS was 19 months. The median OS was shorter in MDS patients with CKs (p = 0.003), intermediate/higher-risk IPSS-R (p = 0.046), poor- cytogenetic risks (p = 0.028), RUNX1 (p = 0.047) or transcription factor (TF) gene mutations (p = 0.011) than those without CKs, poor risk cytogenetics, RUNX1 and TF gene mutation.

Complex karyotype was associated with poor ORR in MDS patients receiving azacitidine monotherapy, therefore, these patients need to be treated with the combination therapy or other treatment regimens rather than azacitidine monotherapy. CKs, intermediate/higher-risk IPSS-R, poor-cytogenetic risks, mutated RUNX1 and transcription factor gene mutations were associated with poor OS in MDS patients.