Background: Therapies for adults with newly diagnosed Ph+ ALL are limited and associated with poor outcomes. PON, a potent TKI, is active against native BCR-ABL1 and all identified single resistance mutations, including T315I, which confers resistance to other TKIs (Zhou. Chem Biol Drug Des 2011;77). In the phase 2 PACE study, PON had a 41% major hematologic response rate in heavily pretreated Ph+ ALL, but responses were not durable mainly due to compound mutations (Cortes. Blood 2018;132; Pritchard. Blood 2016;128). As PON suppresses single BCR-ABL1 resistance mutations, resistance in Ph+ ALL is acquired through compound mutations. Decreased likelihood of compound mutations with first-line PON in Ph+ ALL may lead to more durable responses compared with PON in later lines of therapy. In a phase 2 study of PON with CT in newly diagnosed Ph+ ALL, long-term outcomes were improved vs first/second-generation TKIs (Jabbour. Lancet Haematol 2018;5). The PhALLCON trial compares first-line PON vs IM with reduced-intensity CT. Methods: This open-label trial (NCT03589326) is enrolling 230–320 pts (≥18 y) with newly diagnosed Ph+ or BCR-ABL1–positive ALL (p190/p210) and ECOG status ≤2. Pts are randomized 2:1 to PON 30 mg/d or IM 600 mg/d PO with reduced-intensity CT in induction (cycles [C] 1-3), consolidation (C4-9), and maintenance (C10-20). PON dose is reduced to 15 mg once pt achieves minimal residual disease–negative (MRD−) complete remission (CR). After 20C, pts stay on single-agent PON/IM. CNS prophylaxis: 2x/mo in C1-6. Primary endpoint: MRD− (BCR-ABL/ABL1 ≤0.01%) CR (end of induction). Key secondary endpoint: EFS; others in the Table. Subgroup analysis: pts with/without HSCT. Exploratory endpoints include mutation status. Initiated Aug 2018; to include ~110 sites in ≤35 countries. Currently, 5 active sites (4 US, 1 Spain); accrual ongoing. Clinical trial information: NCT03589326