Philadelphia chromosome-positive acute lymphoblastic leukemia in children: durable responses to chemotherapy associated with low initial white blood cell counts

Abstract

To substantiate the reported sensitivity of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) to St Jude-type multiagent chemotherapy and to identify means of selecting patients most likely to benefit from such treatment, we analyzed the clinical and biologic characteristics of 12 patients with classic Ph+ ALL who were treated in either of two total therapy programs at St Jude Children’s Research Hospital (1989–1994). Event-free survival estimates for this cohort were compared with historical data on 11 patients from an earlier total therapy study (Lancet 1994; 343: 331–332). The prognostic importance of age, white blood cell count and other presenting features was assessed by the logrank test in all 23 patients. Complete remissions were induced in 92% of the patients treated since 1989, compared with 82% of the historical control group (P > 0.05). There was essentially no difference in event-free survival between the study group and historical controls (4-year Kaplan–Meier estimates, 33 ± 19% s.e. vs 36 ± 13%). Further analysis of potentially informative risk factors identified a good-prognosis subgroup defined by an initial white blood cell count of ⩽25 × 10⁹/l and a 4-year event-free survival of 73 ± 19%. In conclusion, intensive multiagent chemotherapy offers an attractive therapeutic option for children and adolescents with Ph+ ALL and low presenting leukocyte count.