Flow-cytometric vs. -morphologic assessment of remission in childhood acute lymphoblastic leukemia: a report from the Children's Oncology Group (COG).

Minimal residual disease (MRD) after initial therapy is integral to risk stratification in B-precursor and T-precursor acute lymphoblastic leukemia (B-ALL, T-ALL). Although MRD determines depth of remission, remission remains defined by morphology. We determined the outcomes of children with discordant assessments of remission by morphology vs. flow cytometry using patients age 1-30.99 years enrolled on Children's Oncology Group ALL trials who underwent bone marrow assessment at the end of induction (N = 9350). Morphologic response was assessed locally as M1 (<5% lymphoblasts; remission), M2 (5-25%), or M3 (>25%). MRD was centrally measured by flow cytometry. Overall, 19.8% of patients with M2/M3 morphology had MRD < 5%. M1 with MRD ≥ 5% was less common in B-ALL (0.9%) than T-ALL (6.9%; p < 0.0001). In B-ALL, M1/MRD ≥ 5% was associated with superior 5-year event-free survival (EFS) than M2/MRD ≥ 5% (59.1% ± 6.5% vs. 39.1% ± 7.9%; p = 0.009), but was inferior to M1/MRD < 5% (87.1% ± 0.4%; p < 0.0001). MRD levels were higher in M2/MRD ≥ 5% than M1/MRD ≥ 5% patients. In T-ALL, EFS was not significantly different between M1/MRD ≥ 5% and M2/MRD ≥ 5%. Patients with morphologic remission but MRD ≥ 5% have outcomes similar to those who fail to achieve morphological remission, and significantly inferior to those with M1 marrows and concordant MRD, suggesting that flow cytometry should augment the definition of remission in ALL.

Cumulative incidence, risk factors, and management of atrial fibrillation in patients receiving ibrutinib.

Atrial fibrillation (AF) has been reported in up to 16% of patients taking ibrutinib. Data regarding the management of AF in this patient population are limited, and stroke prevention poses a challenge because of increased risk of bleeding with ibrutinib treatment. Our study sought to describe the incidence of AF in adult patients treated with ibrutinib for a hematologic malignancy, assess management strategies, evaluate stroke and bleeding outcomes, and identify risk factors for occurrence. Of 582 patients treated with ibrutinib, 76 developed AF. With a median follow-up of 32 months, the estimated cumulative incidence at 6 months, 1 year, and 2 years was 5.9% (95% confidence interval [CI]: 4.2-8.0), 7.5% (95% CI: 5.5-9.9), and 10.3% (95% CI: 8.0-13.0), respectively. Median time to onset of AF was 7.6 months. History of AF and Framingham Heart Study (FHS) AF risk score were found to be significant risk factors for development of AF. Most patients were treated with rate control-only strategies (61.8%), and concomitant aspirin or anticoagulant therapy with ibrutinib was used in 52.6% and 28.9% of patients, respectively. One patient on aspirin developed symptoms consistent with stroke. Nine major bleeds were noted in 7 patients, and 34 clinically relevant nonmajor bleeds were noted in 24 patients. Twenty-one bleeds (4 major bleeds) occurred in 18 patients on aspirin, and 10 bleeds (all clinically relevant nonmajor bleeds) occurred in 6 patients with anticoagulant therapy. These results provide risk factor assessment, impact of management strategies, and outcomes of patients with AF on ibrutinib and serve as basis for formal guidelines.