This is a prospective, single-arm, open-label dose-escalation clinical study to evaluate LVIVO-TaVec400 in the treatment of relapsed/refractory multiple myeloma.

This is a prospective, single-arm, open-label dose-escalation and dose-expansion study, designed to evaluate the safety, tolerability, anti-tumor efficacy profile, and pharmacokinetic characteristics of the LVIVO-TaVec400 in subjects with relapsed/refractory multiple myeloma who have failed at least 3 lines of prior standard therapies. The subject who meet the defined eligibility criteria will be enrolled with a core study period of approximately 2 years, including the screening, bridging therapy(if needed), treatment, and follow-up.

Inclusion Criteria:

1. Subjects voluntarily participate in clinical studies; Fully informed of this study and signed informed consent; Informed consent form must be obtained prior to initiation of any study-related tests or procedures that are not part of the standard treatment for the subject's disease; Good compliance and cooperation with follow-up.
2. Age ≥ 18 years.
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
4. Has measurable lesions
5. Relapsed and/or refractory multiple myeloma
6. Life expectancy≥ 3 months
7. Clinical laboratory values meet screening visit criteria
8. Adequate organ function.

Exclusion Criteria:

1. Prior antitumor therapy with insufficient washout period ;
2. Patients who are positive for hepatitis B surface antigen (HBsAg), hepatitis B virus deoxyribonucleic acid (HBV DNA), hepatitis C antibody (HCV-Ab), hepatitis C virus ribonucleic acid (HCV RNA), and human immunodeficiency virus antibody (HIV-Ab).
3. Those who have experienced life-threatening allergic reactions, hypersensitivity reactions or intolerances to the excipients and related additives of the investigational drug; or those with a previous history of severe allergic reactions (such as hypersensitivity reactions, or those for whom the investigator assesses the need to use glucocorticoids to prevent severe immune-related reactions such as allergic reactions).
4. Any condition deemed by the investigator as rendering the subject unsuitable for participation in this study.
5. Also enrolled in other clinical studies.