Correlation between MRD at the end of induction and EFS in pediatric T-cell lymphoblastic lymphoma

Measurable residual disease (MRD), a test used to detect the presence of lymphoma cells after therapy has shown prognostic significance in both B-cell and T-cell acute lymphoblastic leukemia. However, the correlation between end-of-induction (EOI) MRD and clinical outcomes in patients with T-cell lymphoblastic lymphoma (T-LBL) remains unclear.

Here, we summarize a subgroup analysis of the phase III Children’s Oncology Group AALL1231 trial published by Hayashi et al.¹ in Blood assessing the correlation between EOI MRD and event-free survival (EFS) in patients with T-LBL.

Study design¹

• This was a phase III trial of patients with newly diagnosed Stages II–IV T-cell acute lymphoblastic leukemia or T-LBL
  • Children and young adults were randomized to either the standard therapy arm (A) or with the addition of bortezomib (B)
• Patients with T-LBL who were enrolled in the AALL1231 trial were invited to submit bone marrow samples after induction therapy.
• The primary endpoint was EFS; other endpoints included overall survival (OS).

Key findings¹

• A total of 86 out of the 209 patients with T-LBL volunteered to submit samples, representing 41% of the total population.
• Patients with an MRD of <0.1% (n = 75) at the end of induction experienced a higher four-year EFS rate vs patients with MRD ≥0.1% (n = 11) (Figure 1).
• A significant difference in EFS rates was also observed by treatment arm with patients receiving bortezomib experiencing higher EFS.
• There was no significant difference in overall survival rates by MRD status.
• A significant difference in OS was observed between treatment arms A and B, with those also receiving bortezomib experiencing increased OS rates.
• MRD EOI of ≥0.1% was associated with a lower EFS, irrespective of treatment arm [hazard ratio of 3.73 (1.120–12.4; p = 0.032).
  • There was no significant difference in EFS between treatment arms or increasing MRD at diagnosis.

Figure 1. 4-year EFS and OS rates by MRD*  

EFS, event-free survival; MRD, measurable residual disease; OS, overall survival.  
*Data from Hayashi, et al.¹