Current approach to relapsed acute lymphoblastic leukemia in children

Table 1 Features at primary diagnosis of acute lymphoblastic leukaemia associated with an increased risk of relapse[3]

Clinical features		High-risk group stratification1
Age	Infants < 1 yr old	Yes
	≥ 10 yr	Yes2
WBC	≥ 50 × 109/L	Yes2
Sex	Male	No
Ethnicity	Blacks	No
	Native American	No
	Alaskan Native	No
	Hispanic	No
CNS status	CNS3	No
Response to therapy
Morphological response	PPR	Yes
	Induction failure3	Yes
MRD ≥ 0.01%	After induction (day 33)	Yes
	After consolidation (day 78)
Biology
Immunophenotype	T-cell	No
	Early T-cell precursor	Accepted by some study groups
Genetic alterations	BCR-ABL1	Yes
	MLL translocation	Yes if age < 1 yr
	Hypodiploidy (< 44 chromosomes)	Yes
	TCF3-PBX1 (E2A-PBX1)	No
	TCF3-HLF	Accepted by some study groups
	iAMP21	Accepted by some study groups
	BCR-ABL1-like ALL4	No
	IKZF1 mutation or deletion	No

¹Some features have prognostic importance but are not commonly used in risk stratification;

²The National Cancer Institute (NCI)/Rome risk criteria categorize as high risk patients all those patients with WBC ≥ 50 × 10⁹/L and/or age ≥ 10 yr;

³Induction failure: failure to achieve morphological remission after 4 to 6 wk of induction therapy;

⁴The BCR-ABL1-like or Ph-like ALL with a gene expression profile similar to that of Ph + ALL. ALL: Acute lymphoblastic leukaemia; CNS: Central nervous system; CNS3: ≥ 5 WBC/μL in cerebrospinal fluid with blasts or cranial nerve palsy; MRD: Minimal residual disease; PPR: Poor prednisone response defined as ≥ 1 × 10⁹/L leukemic blasts in the peripheral blood after 1 wk prednisone prophase; WBC: White blood cell count.