Study of YKST02 in Adults With Relapsed or Refractory Multiple Myeloma

Prior treatment

• Prior treatment with any BCMA-targeted therapy, including BCMA-directed chimeric antigen receptor (CAR) T-cell therapy.
• Recent anticancer therapy, investigational medicinal product, radiotherapy, stem cell transplantation, or organ transplantation that does not meet the protocol-defined washout requirements.
• Major surgery or severe trauma shortly before study treatment, or planned major surgery during the study.
• Receipt of a live or live attenuated vaccine within the protocol-defined period before the first dose of study treatment.

Other illness

• Plasma cell leukemia, Waldenström macroglobulinemia, POEMS syndrome, or primary light-chain (AL) amyloidosis.
• Active graft-versus-host disease (GvHD) requiring systemic treatment or clinically significant active GvHD.
• History of another malignancy within the past 5 years, except for adequately treated malignancies with negligible risk of recurrence, as specified in the protocol.
• Symptomatic central nervous system (CNS) metastases, leptomeningeal disease, or evidence of uncontrolled CNS or leptomeningeal involvement that, in the investigator's judgment, makes the participant unsuitable for study participation.
• History of clinically significant central nervous system disorders that may increase study risk or interfere with study participation.
• Known hypersensitivity to monoclonal antibodies, human immunoglobulins, or any component of the study drug.
• Requirement for systemic corticosteroids or other immunosuppressive therapy for conditions other than multiple myeloma that does not meet protocol requirements.
• Active hepatitis B or hepatitis C infection, positive human immunodeficiency virus (HIV) test, or other clinically significant uncontrolled infection requiring systemic therapy.
• Known psychiatric illness or other conditions that may compromise the participant's ability to comply with study requirements.

Lab values

• Clinically significant cardiovascular disease, including recent acute coronary syndrome or coronary revascularization, uncontrolled arrhythmias, New York Heart Association (NYHA) Class III or IV heart failure, clinically significant cardiac dysfunction, prolonged QT interval, or uncontrolled hypertension.
• Any other clinically significant medical condition, laboratory abnormality, or circumstance that, in the investigator's judgment, would make participation in the study inappropriate.

Other

• Uncontrolled pleural effusion, pericardial effusion, or ascites requiring repeated drainage.
• Pregnant or breastfeeding women.

• Able and willing to provide written informed consent (or consent provided by a legally authorized representative, where applicable) and comply with all study procedures.
• Diagnosis of multiple myeloma according to the 2016 International Myeloma Working Group (IMWG) diagnostic criteria.
• Relapsed or refractory multiple myeloma after at least two prior lines of therapy, including prior exposure to a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody.
• Measurable disease as defined in the study protocol.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Estimated life expectancy of at least 12 weeks.
• Recovery from clinically significant toxicities related to prior anticancer therapy to an acceptable level before study treatment (except alopecia).
• Adequate hematologic, hepatic, renal, and coagulation function based on protocol-specified laboratory criteria.
• Women of childbearing potential must have a negative pregnancy test before study treatment and agree to use effective contraception during the study and for 3 months after the last dose of study treatment.
• Male participants must agree to use effective contraception during the study and for 3 months after the last dose of study treatment and must not donate sperm during this period.