• Males or females aged ≥ 18 years, who was histologically or cytologically diagnosed unresectable locally advanced, metastatic or recurrent refractory soft tissue sarcoma.

• Ability to understand and willingness to sign a written informed consent document (ICF). Informed consent of subjects must be performed before the study, and the written informed consent shall be voluntarily signed by himself or his guardian; The subject or his guardian can communicate well with the investigator, and perform according to the protocol.

• Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1.

• Estimated life expectancy, in the judgment of the Investigator, of at least 90 days.

• Adequate bone marrow function, as defined by all of the following:

∙ hemoglobin (Hb) ≥ 90 g/L, and

‣ absolute neutrophil count (ANC) ≥ 1.5x109/L, and

‣ platelet count (PLT) ≥ 75x109/L.

• Adequate liver function, as defined by all of the following:

∙ Total bilirubin ≤ 1.5 × ULN; or ≤ 2.5 × ULN for patients who have serum bilirubin increases due to underlying Gilbert's Syndrome or familial benign unconjugated hyperbilirubinemia.

‣ Aspartate Aminotransferase (AST) ≤ 1.5 × ULN, and Alanine Transaminase (ALT) ≤ 1.5× ULN.

‣ International normalized ratio (INR) or prothrombin time (PT), activated partial thromboplastin time (aPTT) ≤ 1.5×ULN, for subjects who are receiving anticoagulant therapy, INR level should be within therapeutic range.

‣ Amylase and lipase ≤1.5 × ULN

• Adequate renal function as defined by an estimated serum creatinine clearance of ≥ 50 mL/min (calculated by Cockcroft-Gault formula) or serum creatinine≤1.5×ULN.

• Women of childbearing potential must agree to abstain from heterosexual intercourse or use highly effective contraceptive methods from the time of signing informed consent and through 120 days after the last dose of study drug. Should a woman become pregnant or suspect she is pregnant while she (or her partner) is participating in this study, she should inform her research physician immediately.

• a. A woman of childbearing potential is any woman, regardless of sexual orientation, who meets the following criteria: 1. has not undergone tubal ligation, a hysterectomy, or bilateral oophorectomy; or 2. has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months).

• Men enrolled on this study must agree to abstain, be surgically sterilized, or agree to use highly effective methods of contraception, including barrier contraception from the time of signing informed consent and through 120 days after the last dose of study drug.

⁃ Patients should recover from all reversible clinically significant AEs of previous anticancer therapies to baseline or NCI-CTCAE v. 5.0 Grade 0-1, except for alopecia (any Grade), Grade \< 2 sensory or motor peripheral neuropathy, lymphopenia, or hypothyroidism on hormone replacement (Grade 2), within 14 days prior to the first dose on study. Inclusion of patients with other toxicities deemed not clinically significant (Grade ≤ 2) should be discussed and approved by the Medical Head of Sponsor.

⁃ All patients must have at least one measurable lesion as defined by RECIST v1.1 for solid tumors.

⁃ All patients with advanced/metastatic soft tissue sarcoma receiving LVGN6051 combinated with Anlotinib must have received one prior line of approved chemotherapy and disease progresses or intolerance confirmed by imaging examination before enrollment. Approved chemotherapy must include anthracycline, except acinar soft tissue sarcoma and clear cell sarcoma, which can be included in patients with recurrence or metastasis who are newly diagnosed or who only receive surgical treatment.