A Phase 2 Study to Test the Feasibility, Safety and Efficacy of the Addition of Blinatumomab to the Interfant06 Backbone in Infants with Newly Diagnosed KMT2A-Rearranged Acute Lymphoblastic Leukemia. a Collaborative Study of the Interfant Network

Background: Infant acute lymphoblastic leukemia (ALL) is a rare disease with dismal outcome. While outcomes for older children have improved, with event-free survival (EFS) currently above 85%, newly diagnosed infants ( Methods: We conducted a prospective, single-arm, international, multicenter, phase 2 study. Newly diagnosed patients 0.05% before OCTADAD and all HR patients in complete remission were eligible for HSCT. (Serious) Adverse Events ((S)AEs) were collected from the start of blinatumomab until the next treatment block. Outcome data were compared to historical controls. Results: Twenty-eight patients were enrolled. Baseline characteristics are shown in Table 1. The median follow-up was 11 months (range 1.5-33 months). All patients received the full course of blinatumomab without treatment interruptions. Seven SAEs were reported during blinatumomab (3 fever, grade 1 and 4 infections, grade 3-4). None of the patients experienced neurological (S)AEs. In total, 70 AEs were reported, the most frequent grade >3 adverse events were febrile neutropenia (n= 2), anemia (n=5), and elevated GGT (n=2). MRD negative complete response occurred in 54% (n=15/28) at TP blina1, as well as at TP blina2 (after 2 and 4 weeks of blinatumomab, Table 2), which tended to be higher compared to the end of consolidation in Interfant06 (40%, p=0.16). There were 89% (25/28) of patients who were MRD negative or not quantifiable ( Conclusion: This is the first trial to use blinatumomab in infants with newly diagnosed KMT2A-r ALL. Blinatumomab added to the Interfant06 backbone was very well tolerated, and has promising efficacy in terms of a high rate of complete MRD response and short term EFS. Longer follow-up is awaited, but the low relapse rate after blinatumomab is remarkable, given that in historical controls relapses occur frequently and early, during therapy. Given these findings, blinatumomab will be implemented for all infants with newly diagnosed KMT2A-r ALL in the next Interfant21 protocol. Figure 1 Figure 1. Disclosures Nysom: Y-mAbs: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: teaching; EUSA Pharma: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: teaching. Biondi: Amgen: Honoraria; Incyte: Consultancy, Other: Advisory Board; Bluebird: Other: Advisory Board; Novartis: Honoraria; Colmmune: Honoraria. OffLabel Disclosure: Investigational use of blinatumomab