Chemotherapy-Sparing Induction Followed By Consolidation and Maintenance with Blinatumomab and Concurrent Oral Tyrosine Kinase Inhibitor Therapy for Newly-Diagnosed Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia: Primary Endpoint Results from the Blissphall Study

Background: Oral ABL-targeted kinase inhibitors (TKIs) have transformed treatment of BCR::ABL+ (Philadelphia chromosome-positive, Ph+) acute lymphoblastic leukemia (ALL). Induction (IND) w/ corticosteroids (CS) and dasatinib (DAS) alone results in morphologic complete response (mCR) rates approaching 100% but low rates of measurable residual disease (MRD) negativity; addition of intensive chemotherapy to TKIs adds risks of myelosuppression. DAS + the CD3/CD19 bispecific T-cell engager blinatumomab (BLIN) is effective consolidation (CONSOL) for Ph+ ALL, though ABL kinase mutations conferring resistance can arise early in therapy (Foà, NEJM, 2020). We designed a phase II study of BLIN as part of a chemotherapy sparing strategy in pts w/ Ph+ ALL (BLISSPHALL), introducing BLIN as early as 6 weeks into treatment for pts in mCR, w/ aim of expediting MRD clearance and suppressing resistant clones early in disease course, and including a maintenance (MAINT) phase of BLIN + TKI for pts in molecular response.