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Purpose: We tested whether blinatumomab (Blina) is effective as a toxicity-sparing alternative to first-line intensive chemotherapy in children and young persons (CYP) with B-ALL who were chemotherapy-intolerant or chemotherapy-resistant., Methods: Data were collected for consecutive CYP (age 1-24 years) with Philadelphia chromosome-positive or Philadelphia chromosome-negative B-ALL who received Blina as first-line therapy. Blina was given as replacement for postremission intensive chemotherapy to patients with chemotherapy intolerance or resistance. Blina responders received further chemotherapy (Blin-CT) or first remission hematopoietic stem-cell transplant (Blin-HSCT) if indicated. Event-free survival (EFS) and overall survival (OS) of the Blin-CT group were compared with those of matched controls treated with standard chemotherapy in the UKALL 2003 trial. Events were defined as death, relapse, or secondary cancer., Results: From February 2018 to February 2023, 105 patients were treated, of whom 85 were in the Blin-CT group and 20 were in the Blin-HSCT group. A majority of Blin-CT patients received Blina for chemotherapy intolerance (70 of 85, 82%), and the group had a higher-risk profile than unselected patients with B-ALL. Blina was well tolerated with only one patient having a grade 3/4-related toxicity event, and of the 60 patients who were minimal residual disease-positive pre-Blina, 58 of 60 (97%) responded. At a median follow-up of 22 months, the 2-year outcomes of the 80 matched Blin-CT group patients were similar to those of 192 controls (EFS, 95% [95% CI, 85 to 98] v 90% [95% CI, 65 to 93] and OS, 97% [95% CI, 86 to 99] v 94% [95% CI, 89 to 96]). Of the 20 in the HSCT group, three died because of transplant complications and two relapsed., Conclusion: Blina is safe and effective in first-line treatment of chemotherapy-intolerant CYP with ALL.

Purpose: The aim of the randomized trial, UKALL2003, was to adjust treatment intensity on the basis of minimal residual disease (MRD) stratification for children and young adults with acute lymphoblastic leukemia. We analyzed the 10-year randomized outcomes and the time for patients to be considered cured (ClinicalTrials.gov identifier: NCT00222612)., Methods: A total of 3,113 patients were analyzed including 1,054 patients who underwent random assignment (521 MRD low-risk and 533 MRD high-risk patients). Time to cure was defined as the point at which the chance of relapse was < 1%. The median follow-up time was 10.98 (interquartile range, 9.19-13.02) years, and survival rates are quoted at 10 years., Results: In the low-risk group, the event-free survival was 91.7% (95% CI, 87.4 to 94.6) with one course of delayed intensification versus 93.7% (95% CI, 89.9 to 96.1) with two delayed intensifications (adjusted hazard ratio, 0.73; 95% CI, 0.38 to 1.40; P = .3). In the high-risk group, the event-free survival was 82.1% (95% CI, 76.9 to 86.2) with standard therapy versus 87.1% (95% CI, 82.4 to 90.6) with augmented therapy (adjusted hazard ratio, 0.68; 95% CI, 0.44 to 1.06; P = .09). Cytogenetic high-risk patients treated on augmented therapy had a lower relapse risk (22.1%; 95% CI, 15.1 to 31.6) versus standard therapy (52.4%; 95% CI, 28.9 to 80.1; P = .016). The initial risk of relapse differed significantly by sex, age, MRD, and genetics, but the risk of relapse for all subgroups quickly coalesced at around 6 years after diagnosis., Conclusion: Long-term outcomes of the UKALL2003 trial confirm that low-risk patients can safely de-escalate therapy, while intensified therapy benefits patients with high-risk cytogenetics. Regardless of prognosis, the time to cure is similar across risk groups. This will facilitate communication to patients and families who pose the question "When am I/is my child cured?"

Purpose Minimal residual disease (MRD) and genetic abnormalities are important risk factors for outcome in acute lymphoblastic leukemia. Current risk algorithms dichotomize MRD data and do not assimilate genetics when assigning MRD risk, which reduces predictive accuracy. The aim of our study was to exploit the full power of MRD by examining it as a continuous variable and to integrate it with genetics. Patients and Methods We used a population-based cohort of 3,113 patients who were treated in UKALL2003, with a median follow-up of 7 years. MRD was evaluated by polymerase chain reaction analysis of Ig/TCR gene rearrangements, and patients were assigned to a genetic subtype on the basis of immunophenotype, cytogenetics, and fluorescence in situ hybridization. To examine response kinetics at the end of induction, we log-transformed the absolute MRD value and examined its distribution across subgroups. Results MRD was log normally distributed at the end of induction. MRD distributions of patients with distinct genetic subtypes were different ( P < .001). Patients with good-risk cytogenetics demonstrated the fastest disease clearance, whereas patients with high-risk genetics and T-cell acute lymphoblastic leukemia responded more slowly. The risk of relapse was correlated with MRD kinetics, and each log reduction in disease level reduced the risk by 20% (hazard ratio, 0.80; 95% CI, 0.77 to 0.83; P < .001). Although the risk of relapse was directly proportional to the MRD level within each genetic risk group, absolute relapse rate that was associated with a specific MRD value or category varied significantly by genetic subtype. Integration of genetic subtype-specific MRD values allowed more refined risk group stratification. Conclusion A single threshold for assigning patients to an MRD risk group does not reflect the response kinetics of the different genetic subtypes. Future risk algorithms should integrate genetics with MRD to accurately identify patients with the lowest and highest risk of relapse.

Purpose Our aim was to determine the role of end-of-induction (EOI) minimal residual disease (MRD) assessment in the identification and stratification of induction failure in patients with pediatric acute lymphoblastic leukemia (ALL) and to identify genetic abnormalities that drive disease in these patients. Patients and Methods Analysis included 3,113 patients who were treated in the Medical Research Council UKALL2003 multicenter randomized trial (NCT00222612) between 2003 and 2011. MRD was measured by using standardized real-time quantitative PCR. Median follow-up was 5 years 9 months. Results Fifty-nine patients (1.9%) had morphologic induction failure with 5-year event-free survival (EFS) of 50.7% (95% CI, 37.4 to 64.0) and 5-year overall survival of 57.7% (95% CI, 44.2 to 71.2). Of these, a small proportion of patients with M2 marrow (6 of 44) and a low EOI MRD level (< 0.01%) had 5-year EFS of 100%. Conversely, among patients with morphologic remission 2.3% (61 of 2,633) had high MRD (≥ 5%) and 5-year EFS of 47.0% (95% CI, 32.9 to 61.1), which was similar to those with morphologic induction failure. Redefining induction failure to include morphologic induction failure and/or MRD ≥ 5% identified 3.9% (120 of 3,133 patients) of the trial cohort with 5-year EFS of 48.0% (95% CI, 39.3 to 58.6). Induction failure (morphologic or MRD ≥ 5%) occurred most frequently in T-ALL (10.1%; 39 of 386 T-ALL cases) and B-other ALL, that is, lacking established chromosomal abnormalities (5.6%; 43 of 772 B-other cases). Genetic testing within the B-other group revealed the presence of PDGFRB gene fusions, particularly EBF1-PDGFRB, in almost one third of B-other ALL cases. Conclusion Integration of EOI MRD level with morphology identifies induction failure more precisely than morphology alone. Prevalence of EBF1-PDGFRB fusions in this group highlights the importance of genetic screening to identify abnormalities that may be targets for novel agents.