An open-label, first-in-human, dose-escalation/expansion study of SAR443579 administered as single agent by intravenous infusion in adult and pediatric participants with relapsed or refractory acute myeloid leukemia (R/R AML), B-cell acute lymphoblastic leukemia (B-ALL), high risk-myelodysplasia (HR-MDS), or blastic plasmacytoid dendritic cell neoplasm (BPDCN)

This study is open to both men and women, aged 18 years and older. There is no upper age limit for participants.

To be considered for this study, you must have one of the specific blood cancers mentioned: acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (B-ALL), high-risk myelodysplastic syndrome (HR-MDS), or blastic plasmacytoid dendritic cell neoplasm (BPDCN). Importantly, your cancer must be resistant to standard treatments or have returned after treatment.

Specific medical tests will be done to confirm if you meet all the necessary health criteria for taking part. Your doctor will be able to tell you if this study might be a suitable option for your particular situation.

If you join this study, you'll receive the study medicine, SAR443579, through a drip into your vein. You'll also be given other common medicines like antihistamines (promethazine, diphenhydramine, cetirizine, dexchlorpheniramine) and paracetamol, which are used to help prevent or manage possible reactions to the new treatment. Because this is an early-stage study, you will have frequent visits to the clinic for medical check-ups, blood tests, and scans. These visits are very important for the study team to carefully monitor your health, how you are reacting to the medicine, and how well it's working.

The study starts by finding the right dose, so the amount of SAR443579 you receive might change. Close monitoring for side effects is a key part of the first stage. The total duration of your participation will depend on how you respond to the treatment and the study plan, but you should expect regular follow-up appointments and checks for an extended period.