This study is aimed to evaluate the efficacy, safety, immunogenicity and pharmkinetics, pharmacodynamics of 6MW3211 as monotherapy and in combination with AZA or AZA plus VEN in patients with AML/MDS.

This study is a phase I/II study to evaluate the pharmacokinetics, pharmacodynamics, efficacy and safety of 6MW3211 monotherapy or combined with AZA or AZA plus VEN in patients with AML and MDS. There will be 2 parts of this study. The phase Ib is about monotherapy of 6MW3211 and Phase II is designed to evaluate the safety and efficacy of 6MW3211 combined with AZA or AZA plus VEN in patients with relapse/refractory and newly diagnosed AML and MDS.

Inclusion Criteria:

• Voluntarily participate in the study and sign the informed consent;
• 18≤age≤75，Men or women；
• AML patients (except acute promyelocytic leukemia) : subjects who meet the diagnostic criteria for relapsed/refractory AML according to the diagnostic criteria of 2021 Chinese Guidelines for the Diagnosis and Treatment of Relapsed and Refractory AML ； MDS patients: MDS patients were diagnosed as having moderate risk of recurrence/refractory (IPSS-R score >3.5) according to WHO diagnostic criteria in 2016
• ECOG:0-2;
• Survival expectation of at least 3 months;
• Adequate organs and hematopoietic functions; only applicable for phase II :
• Newly diagnosed AML with intolerance to standard induction chemotherapy who should meet one of following criterias: age ≥75 years; ECOG 2-3; chronic heart failure requiring treatment or EF≤50% or chronic stable angina pectoris; DLCO≤65% or FEV1≤65%;30ml/min≤CrCl<45ml/min；1.5 x ULN\