NOTCH1 pathway activating mutations and clonal evolution in pediatric T-cell acute lymphoblastic leukemia

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Activating NOTCH1 signaling, driven by NOTCH1/FBXW7 alterations, is a major oncogenic driver in T-cell acute lymphoblastic leukemia (T-ALL).
• The molecular mechanisms underlying T-ALL relapse remain incompletely understood.
• Understanding these mechanisms is crucial for developing targeted therapies and improving patient outcomes.

Purpose of the Study:

• To investigate the role of NOTCH1/FBXW7 mutations in T-ALL relapse.
• To analyze clonal evolution from diagnosis to relapse in pediatric T-ALL patients.
• To identify specific mutation patterns associated with disease recurrence.

Main Methods:

• Whole-exome sequencing of 30 pediatric T-ALL cases.
• Amplicon-based deep sequencing of 11 diagnosis-relapse paired samples.
• Comparative analysis of mutation profiles between diagnosis and relapse stages.

Main Results:

• NOTCH1/FBXW7 alterations were prevalent in both diagnosis (73.3%) and relapse (72.7%) samples.
• A shift in mutation type was observed, with PEST domain alterations becoming more frequent at relapse (54.5%) compared to diagnosis.
• NOTCH1 "switching" (different mutations in the major clone between diagnosis and relapse) was identified in 2 out of 11 paired cases and in a separate cohort, underscoring NOTCH1's dynamic role.

Conclusions:

• NOTCH1 mutations are critical in both the initiation and progression of T-ALL.
• The observed shift in NOTCH1 mutation types and the phenomenon of NOTCH1 "switching" suggest a role in T-ALL relapse.
• Further research with larger cohorts and minimal residual disease-based protocols is warranted to confirm these findings and their clinical implications.