PEST domain NOTCH mutations confer a poor relapse free survival in pediatric T-ALL: Data from a tertiary care centre in India.

A comprehensive genotype-phenotype analysis of pediatric T-ALL data was performed. 33 confirmed pediatric (≤12 y) T-ALL samples were evaluated for oncogenic transcripts: TLX-1, TLX-3, common fusion of STIL-TAL1, NOTCH1 mutations and copy number variations (CNVs). Mean WBC was 235.69 × 103/μL. TLX1 and TLX-3 overexpression detected in 1 (3%) and 7 (21%) patients and STIL-TAL1 in 8 (27%). NOTCH1 mutations were noted in 17 (52%), of which 12 (71%) in HD domain and 6 (35%) in PEST domain (including one case with mutations in all three domains). Commonest CNVs were CDKN2A (85%) and CDKN2B (75%). Relapse occurred in 8 (24%) patients. The median follow-up was 15 months (range: 0.5-36). Bulky liver (p = 0.025), day 35 marrow (p = 0.004) and NOTCH mutation (p = 0.046) were predictive of time to an event. RFS was significantly poor for cases with PEST Vs. HD domain mutations (50% Vs. 85%) (p = 0.0009). Though cases with PEST domain NOTCH mutations had poor RFS, the OS was not influenced by NOTCH mutation positivity.