Excellent Prognosis of Children with ETV6-RUNX1 Positive (+) Acute Lymphoblastic Leukemia (ALL) in the FRALLE 2000 Protocol.

Abstract 1628

Poster Board I-654

Since the cloning of the t(12 ;21) in 1995 the prognosis of children with ETV6-RUNX1(+)ALL seems to further increase in the current era. From december 2000 to july 2008, 1461 children and adolescents aged from 1 to 20 years with B cell lineage ALL have been treated according the FRALLE protocols: one for standard-risk (SR) ALL (age 1-9 y, WBC < 50 G/L, no extra medullary involvement) F2000-A; the other one FRALLE 2000-B for high and very high risk ALL (HR) (all other pts). The two protocols mainly differ by a larger use of dexamethasone and a reduced use of anthracyclins in F2000A and the use of HDMTX and a double delayed intensification in FRALLE 2000B. ETV6-RUNX1 presence has been assessed by RT-PCR in 1392 pts (i.e. 96%) and found positive in 321 pts, i.e. 23%. Initial features include a median age of 4.2 y (1.2-15.6), a sex ratio (M/F) of 1.2, a median WBC of 10 G/L(1-293). Both peripheral blood D8 response to prednisone (PRED) and D21 marrow response to chemotherapy were evaluable in 316 pts: 94% of the pts have a rapid early response at D8 and D21. Only 3% of the pts were qualified as D8 poor PRED responders and 3% slow marrow responders at D21. The D35-42 CR rate is 100%. End of induction (EOI) minimal residual disease (MRD) using Ig-TCR methods is known in 259 out of 321 pts (81%) pts. Only 4 pts (2%) had a very high (≥10-2) EOI-MRD. Five year EFS, DFS and OS are 95±2%, 95±2%, 98±1%, respectively. The 5y EFS is 96±2% for the 252 SR pts and 90±7% for the 69 HR pts, p=0.30. The 5y EFS is significantly better for children with ETV6-RUNX1(+)ALL compared to those with ETV6-RUNX1(-) B-lineage ALL: 95±2% vs 84±2%, respectively (p=.001). Nine relapses have been reported in the bone marrow (4) the testis (4), the CNS (1) after a median time of 44 m (25-68), i.e. significantly longer than in the ETV6-RUNX1(-) cases (28m (1-92), p=.01). More testis relapses are observed in boys with ETV6-RUNX1(+)ALL (4 out 7 relapses vs 2 out of 62 in boys with ETV6-RUNX1(-) ALL). These results represent a significant progress compared to the previous protocol F 93 (191 children) both in terms of EFS and overall survival (5y EFS: 95±2% vs 78±3%, p=.001; 5 y OS: 98±1% vs 92±2%, p=.001).