Results of CoALL 07-03 study childhood ALL based on combined risk assessment by in vivo and in vitro pharmacosensitivity.

We conducted a clinical trial and report the long-term outcome of 773 children with acute lymphoblastic leukemia upon risk-adapted therapy accrued in trial CoALL 07-03 (from the Cooperative Study Group for Childhood Acute Lymphoblastic Leukemia). In a 2-step stratification, patients were allocated to receive either low- or high-risk treatment, based on initial white blood cell count, age, and immunophenotype. A second stratification was performed according to the results of in vitro pharmacosensitivity toward prednisolone, vincristine, and asparaginase (PVA score) and in vivo response after induction therapy (minimal residual disease [MRD]). Therapy was reduced for both risk groups in patients with a low PVA score or negative MRD result, and intensified in patients with a high PVA score. Overall outcome improved significantly compared with the predecessor CoALL 06-97 trial, with identical therapy backbone despite treatment reduction in 15.8% of patients (10-year probability of event-free survival, 83.5% vs 73.9%; overall survival, 90.7% vs 83.8%). Outcome for patients in the reduced treatment arms was superior to that of patients in the standard arms, associated with a profound reduction in frequency and severity of infectious complications. Importantly, we observed a lack of correlation between in vitro and in vivo drug response, as well as a lower predictive value of in vitro drug testing, reflecting an intrinsic limitation of this methodology that prevents its use for treatment stratification in future trials. In conclusion, it might be possible to reduce chemotherapy in children with acute lymphoblastic leukemia selected by stringent in vivo measurement of MRD without jeopardizing overall outcome.

Daunorubicin during delayed intensification decreases the incidence of infectious complications - a randomized comparison in trial CoALL 08-09.

Anthracyclines are integral components of antileukemic treatment. Apart from cardiotoxicity, myelosuppression and infectious complications have been described for doxorubicin (DOX) and daunorubicin (DNR) as predominant side effects, but little is known about their differential toxicities. To address the question whether DNR is associated with a lower rate of infectious complications compared with DOX, 307 children with newly diagnosed acute lymphoblastic leukemia, enrolled in trial CoALL 08-09, were randomized to receive either DOX 30 mg/m2 (n = 153) or DNR 36 mg/m2 (n = 154) in delayed intensification. Hematologic toxicities and stomatitis were less frequent in the DNR group resulting in a significantly lower rate of infections in the DNR arm (27% vs. 59%, p < .0001). Survival was equal in both arms (95% SE 2%) (p = .55), with an insignificant difference in the relapse rate (RR 0.12 (SE = 0.03) in the DOX arm vs. 0.16 (SE = 0.04) in the DNR arm; p = .37; Hazard ratio 1.3; 95% confidence interval 0.7-2.6). In conclusion, DNR given in delayed intensification is associated with a lower incidence of infectious complications without loss of efficacy.