Merck makes a new move in Astra battle
The group is pitting its anti-CD19 T-cell engager MK-1045 head-to-head against Blincyto.
The group is pitting its anti-CD19 T-cell engager MK-1045 head-to-head against Blincyto.
Merck & Co, lagging behind AstraZeneca in the race to get a next-gen CD19-targeting T-cell engager to market, will soon start the first pivotal trial of its contender, MK-1045, a new listing on clinicaltrials.gov reveals.
Unlike Astra, however, Merck is taking aim at a relapsed/refractory setting – namely B-cell acute lymphoblastic leukaemia. Another difference is that Merck is testing its project head-to-head against Amgen’s approved Bite-format anti-CD19 T-cell engager Blincyto, something that Astra so far isn’t doing.
Better than Blincyto?
Both groups are trying to improve on Blincyto, which is approved for relapsed/refractory B-ALL, but carries boxed warnings of CRS and neurotoxicity.
Blincyto’s dosing schedule is also arduous, involving continuous infusion over four weeks, followed by two weeks without infusion – although Amgen is working on a subcutaneous version. Despite all this, Blincyto still sold $1.6bn in 2025.
And Merck is the first to be challenging the Amgen drug directly. Three phase 3 studies of Astra’s candidate, surovatamig, have already been listed on the clinical trials registry: Soundtrack-F1 in first-line follicular lymphoma; Soundtrack-D2 in first-line LBCL (elderly/unfit patients); and Soundtrack-C1 as consolidation therapy in chronic lymphocytic leukaemia.
The last trial is testing a subcutaneous formulation of surovatamig; the other two studies make no mention of the molecule's route of administration, and are assumed to be evaluating an IV version.
The phase 3 battle of anti-CD19 T-cell engagers
| MK-1045 (Merck & Co) | Surovatamig (AstraZeneca) | |
|---|---|---|
| r/r B-ALL | MK-1045-005*, monoRx vs Blincyto, to start May 2026 | N/A |
| 1st-line FL | N/A | Soundtrack-F1, + Rituxan, vs chemo, data due 2027+ |
| 1st-line LBCL | N/A | Soundtrack-D2, + R-mini-Chop, vs R-mini-Chop in elderly/unfit pts, data due 2027+ |
| CLL/SLL | N/A | Soundtrack-C1, monoRx** as consolidation, vs observation, estimated start Apr 2026 |
Note: *phase 2/3; **SC surovatamig. Source: OncologyPipeline & clinicaltrials.gov.
Merck’s trial, known as MK-1045-005 and due to start in May, is testing an IV formulation. The phase 2/3 will include a dose-optimisation phase before the randomised phase against Blincyto, and primary efficacy endpoints are the proportion of patients with complete remission (for parts one and two), and overall survival (part two only).
Astra’s trials are classed as phase 3s, but also include dose-finding phases. The UK group raised eyebrows by jumping straight from phase 1 into pivotal trials, but Merck also looks to be taking a risk with MK-1045, which it licensed from China’s Curon Biopharmaceutical in 2024 for $700m up front. At the time the asset, then known as CN201, had produced data from early-stage Chinese studies.
Chinese phase 1/2 data in relapsed/refractory B-ALL were presented at last year’s ASH meeting. MK-1045 produced a CR/CRi/CRh rate of 55% among 73 patients across doses, rising to 83% among 24 patients receiving target doses of 60mg or more. In the Tower trial, Blincyto produced a CR/CRh rate of 42%.
Merck is also starting a global phase 1/2 study in relapsed/refractory follicular lymphoma and DLBCL, testing both IV and SC formulations of MK-1045. Merck has rights to Alteogen’s Hybrozyme technology for use in its SC version of Keytruda, and presumably it’s also using this for MK-1045.
Mystery also surrounds the SC formulation of surovatamig, although Astra also signed a deal with Alteogen last year covering unknown projects.
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