Journal of Leukemia
Open Access

Abstract

Clinical Significance of WT1 mRNA Levels in Japanese Acute Lymphoblastic Leukemia Patients

Yoshiko Hashii, Yoshiyuki Kosaka, Kenichiro Watanabe, Koji Kato, Masue Imaizumi, Takashi Kaneko, Shosuke Sunami, Arata Watanabe, Hidefumi Hiramatsu, Yuhki Koga, Masahiro Hirayama, Takafumi Nakao, Tomoko Hata, Naoyuki Uchida, Ken Ishiyama, Kinuko Mitani, Michihiro Hidaka, Kunio Kitamura, Hiroko Tsunemine, Yasunori Ueda, Atsuko Mugitani, Kensuke Usuki,

This study enrolled 49 patients with de novo childhood acute lymphoblastic leukemia (ALL) and 19 adult patients with ALL. WT1 mRNA showed high positive expression rates of 90% or more in ALL patients, and fusion gene transcripts were detected in 22.4% of childhood ALL cases prior to treatment. During follow-up at 4-6 months, WT1 mRNA levels in childhood ALL cases were observed to be lower in patients undergoing hematological remission after treatment when compared to the initial stages. We also assessed hematological remission via ROC analysis. The upper cut-off values were calculated to be 220 and 1,820 copies/μg RNA in the peripheral blood (PB) and bone marrow (BM) samples, respectively. Since 50 copies/μg RNA was determined to be both, the limit of detection (LOD) and minimal residual disease (MRD) threshold, WT1 mRNA regions below the upper cut-off values indicated remission depth. The detection of high WT1 mRNA levels, even in patients without fusion gene transcripts, reflected the treatment effects and remission depth, demonstrating its capacity to be a useful MRD monitoring marker in ALL.