A Study of Safety and Efficacy of Sirolimus for Injection (Albumin-bound) in Patients With Advanced Malignant Perivascular Epithelioid Cell Tumor (PEComa)

Inclusion Criteria: * Aged 18 years or older, and Phase Ⅰb: Patients with histologically confirmed diagnosis of advanced soft tissue sarcomas (including malignant PEComa, accounting for at least 1/2) have failed standard treatment (disease progression or relapse or intolerance to chemotherapy, radiotherapy, targeted therapy, etc.) or lack effective treatment; Phase Ⅱ: Patients must have a histologically confirmed diagnosis of malignant PEComa that is either metastatic or locally advanced and for which surgery is not a recommended option. \[Malignant PEComas displaying 2 or more of the features of large size (\> 5 cm), infiltrative growth, high nuclear grade, cellular necrosis, mitoses ≥1/50 high power field (HPF), or vascular invasion\] * At least 1 measurable lesion as defined by RECIST 1.1. * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. * Life expectancy \>3 months. * Patient must have the following biological parameters levels at screening (without blood transfusion, EPO, G-CSF and other medical support within14 days prior to screening tests): Blood tests: Absolute neutrophil count (ANC) ≥1.5 × 10\^9/L; Platelet count ≥100 × 10\^9/L; Hemoglobin ≥90 g/L; Renal function tests: serum creatinine ≤1.5 x upper limit of normal (ULN); Liver function tests: Total bilirubin ≤1.5 x ULN (Patients with liver metastases, bile duct obstruction, or confirmed Gilbert syndrome: ≤ 3×ULN); AST and ALT ≤2.5 x ULN (≤5 x ULN if attributable to liver metastases); Blood…