Utility of Flow Cytometry for Prognostic Prediction in Adult T-Cell Leukemia/Lymphoma.

INTRODUCTION

Adult T-cell leukemia/lymphoma (ATL) exhibits marked clinical heterogeneity; however, current classification primarily rely on morphology and laboratory findings and require further advancement. This study aimed to evaluate the roles of human T-lymphotropic virus type 1 (HTLV-1)-infected cell (CD4-positive T cell) analysis system using flow cytometry (HAS-Flow) and absolute CD4 count in prognostic assessment of nonaggressive ATL.

METHODS

We retrospectively analyzed 227 individuals with HTLV-1 infection in Japan (derivation cohort) and 81 in the United Kingdom (validation cohort). HAS-Flow categorized patients into G1-G4 groups according to the proportion of cell adhesion molecule 1 (CADM1)+/CD7- cells. Clinical outcomes were compared by HAS-Flow and absolute CD4 count (cutoff: 1500 cells/µL) using Kaplan-Meier and Cox analyses.

RESULTS

In the derivation cohort, 4-year progression-free survival (PFS) rates were 100% for G1-G2, 94.2% for G3, and 55.7% for G4 (p < 0.01). Absolute CD4 counts >1500 cells/µL identified patients with significantly shorter PFS and overall survival. G4 patients showed poor prognosis irrespective of CD4 counts. The UK validation cohort reproduced the prognostic CD4 counts >1500 cells/µL.

CONCLUSION

HAS-Flow and absolute CD4 count provide additive prognostic information beyond the Shimoyama classification.

TRIAL REGISTRATION: The authors have confirmed clinical trial registration is not needed for this submission.