The goal of this phase 2 trial is to test the safety and efficacy of selinexor combined with ixazomib and lenalidomide as maintenance therapy in patients with multiple myeloma.

The investigators will evaluate safety and efficacy of selinexor combined with ixazomib and lenalidomide as maintenance therapy in patients with multiple myeloma post complete remission. Event-free survival (EFS), progression-free survival (PFS), overall survival (OS), adverse events (AEs) will be assessed.

Inclusion Criteria:

• Pathologically confirmed Multiple Myeloma according World Health Organization (WHO) classification;
• Patient is ≥ 18 years of age at the time of signing the informed consent form (ICF).
• Patient must understand and voluntarily sign an ICF prior to any study-specific assessments/procedures being conducted;
• Patient is willing and able to adhere to the study visit schedule and other protocol requirements;
• Documented response to ASCT (PR, VGPR, CR/stringent complete response [sCR]) according to IMWG criteria.

Exclusion Criteria:

• Active or uncontrolled infections requiring systemic treatment within 14 days before enrollment.
• Any instability of systemic disease, including but not limited to severe cardiac, liver, kidney, or metabolic disease need therapy.
• Pregnant or lactating women