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‹ Mon · 27 Jul 2026
Novel or significantly improved treatment

Phase 1 clinical trial of S64315, an intravenous MCL1 inhibitor, in patients with myeloid malignancies.

First human evidence shows an MCL1-blocking drug can be given safely to patients with hard-to-treat blood cancers, opening a new treatment pathway.

S64315 is a first-in-class intravenous inhibitor of MCL1, a key anti-apoptotic protein overexpressed in many hematologic cancers, evaluated in a Phase 1 dose-escalation study in patients with refractory myeloid malignancies. This trial provides the first human clinical evidence for MCL1 inhibition as a therapeutic strategy, addressing a major unmet need in AML and MDS where available salvage options are limited.

What the study was

Study design
Phase 1 dose-escalation clinical trial
Population
Patients with refractory/relapsed myeloid malignancies (AML, MDS, MPN)
Category
Drug Development
Maturity
Exploratory
Journal
Leukemia & lymphoma

Why it surfaced

Phase 1 first-in-human trial of MCL1 inhibitor, a long-validated but previously undruggable target. AML/MDS represents one of the highest unmet needs in hematology. Clinical Phase 1 data from a multicenter trial with leading hematology centers (Vey, Montesinos, Daver, Wei).

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