Predicting Response to Selinexor-Based Therapy in Relapsed/Refractory Multiple Myeloma: A Multicenter Prospective Study

Inclusion Criteria: 1. Patients with a confirmed diagnosis of multiple myeloma (MM) based on bone marrow aspiration or biopsy, in accordance with the International Myeloma Working Group (IMWG) criteria. 2. Patients with relapsed/refractory MM after 2-4 prior lines of therapy. 3. Age ≥18 years. 4. Provision of written informed consent, with willingness to participate in the study and to provide relevant clinical samples and follow-up information. Exclusion Criteria: 1. Patients with relapsed MM whose toxicities from prior chemotherapy have not recovered to baseline or ≤ Grade 1. 2. Presence of other active malignancies or severe systemic diseases (e.g., significant cardiovascular or cerebrovascular disease, hepatic or renal insufficiency) that may affect study outcomes or limit tolerance to treatment or follow-up. 3. Prior history of bone marrow transplantation or other treatments that may affect the bone marrow microenvironment or immune function within 6 months before study initiation. 4. Known hypersensitivity to selinexor, ixazomib, or any components of the study drugs, or a history of severe allergic reactions. 5. Known human immunodeficiency virus (HIV) infection (HIV antibody positive). 6. Participation in another clinical trial within 30 days prior to study initiation or during the study period. 7. Pregnant or breastfeeding women. 8. Patients with psychiatric disorders or those unable to comply with study procedures.