Merck Launches First Pivotal Trial of CD19 T-Cell Engager MK-1045 Against Blincyto in B-ALL
核心洞察
Merck & Co (搜索) will start the first pivotal trial of MK-1045, a next-generation CD19 (搜索)-targeting T-cell engager, in May 2026 for relapsed/refractory B-cell acute lymphoblastic leukemia (搜索).
The phase 2/3 study will directly compare MK-1045 against Amgen's approved Blincyto, marking the first head-to-head challenge to the established therapy.
Early Chinese phase 1/2 data showed MK-1045 achieved an 83% complete remission rate at target doses, compared to Blincyto's 42% rate in the Tower trial.
Merck & Co (搜索) is set to launch its first pivotal trial of MK-1045, a next-generation CD19 (搜索)-targeting T-cell engager, in May 2026, marking a significant escalation in the competitive race against AstraZeneca's surovatamig (搜索). The phase 2/3 study will test MK-1045 directly against Amgen's established therapy Blincyto in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (搜索).
Direct Challenge to Blincyto
The upcoming trial, designated MK-1045-005, represents the first direct head-to-head comparison against Blincyto, distinguishing Merck's approach from AstraZeneca's strategy. While AstraZeneca has launched three phase 3 studies of surovatamig (搜索) in different indications, none directly challenge Blincyto in the relapsed/refractory setting.
The study will include a dose-optimization phase before proceeding to the randomized comparison against Blincyto. Primary efficacy endpoints include the proportion of patients achieving complete remission for both study phases, with overall survival as an additional primary endpoint for the randomized portion.
Promising Early Data
MK-1045 has demonstrated encouraging results in early-stage Chinese studies. Phase 1/2 data presented at the ASH meeting showed a complete remission rate of 55% among 73 patients across all doses, with the response rate climbing to 83% among 24 patients receiving target doses of 60mg or more. This compares favorably to Blincyto's 42% complete remission rate in the Tower trial.
Merck acquired global rights to MK-1045, originally known as CN201, through a $700 million deal with China's Curon Biopharmaceutical (搜索) in 2024. At the time of acquisition, the asset had generated data from early-stage Chinese studies.
Competitive Landscape
Both Merck and AstraZeneca are attempting to improve upon Blincyto, which carries boxed warnings for cytokine release syndrome and neurotoxicity despite generating $1.6 billion in sales in 2025. Blincyto's dosing schedule requires continuous infusion over four weeks followed by two weeks without treatment, presenting an opportunity for more convenient alternatives.
AstraZeneca currently leads the race with three ongoing phase 3 studies of surovatamig (搜索): Soundtrack-F1 in first-line follicular lymphoma (搜索), Soundtrack-D2 in first-line large B-cell lymphoma (搜索) for elderly/unfit patients, and Soundtrack-C1 as consolidation therapy in chronic lymphocytic leukemia (搜索). The company acquired rights to surovatamig through its 2022 acquisition of Teneotwo for $100 million upfront.
Subcutaneous Formulations in Development
Both companies are pursuing subcutaneous formulations to improve convenience. AstraZeneca's Soundtrack-C1 trial is testing a subcutaneous version of surovatamig (搜索), marking the first disclosure of this route of administration for the drug. The subcutaneous formulation may utilize technology licensed from drug delivery specialist Alteogen.
Merck is also developing both intravenous and subcutaneous formulations of MK-1045 in a separate global phase 1/2 study for relapsed/refractory follicular lymphoma (搜索) and diffuse large B-cell lymphoma (搜索). The company has rights to Alteogen's Hybrozyme technology, which it uses for its subcutaneous version of Keytruda.
Market Implications
The competitive dynamics reflect the significant market opportunity in CD19 (搜索)-targeting therapies. Novartis recently abandoned its anti-CD19 x CD2 trispecific T-cell engager PIT565 in cancer indications, though autoimmune applications continue, highlighting the challenges in this therapeutic area.
Both companies are taking calculated risks by advancing to phase 3 studies with limited clinical data. AstraZeneca raised eyebrows by jumping directly from phase 1 to phase 3 trials, while Merck is similarly advancing MK-1045 based primarily on Chinese study data.