To evaluate the safety and tolerability of intraperitoneal PX in combination with nab-paclitaxel in patients with peritoneal metastatic mucinous adenocarcinoma, and to determine the maximum tolerated dose (MTD) and the recommended Phase II dose (RP2D).

Inclusion Criteria:

• Age ≥ 18 years, regardless of sex;
• Histologically confirmed peritoneal metastatic mucinous adenocarcinoma;
• Considered suitable for intraperitoneal therapy based on investigator assessment;
• ECOG performance status 0-2;
• Adequate organ function confirmed by laboratory tests within 7 days prior to enrollment:
• Hematology: ANC ≥ 1.5 × 10⁹/L; PLT ≥ 100 × 10⁹/L; Hb ≥ 85 g/L; Liver function: TBIL ≤ 1.5 × ULN (≤ 3 × ULN for Gilbert's syndrome);AST/ALT ≤ 3 × ULN (≤ 5 × ULN in patients with liver metastases); Renal function: creatinine clearance ≥ 60 mL/min (Cockcroft-Gault) or serum creatinine ≤ 1.5 × ULN; Coagulation: PT, INR, and APTT ≤ 1.5 × ULN;
• Life expectancy ≥ 3 months;
• Ability to understand and willingness to sign written informed consent.

Exclusion Criteria:

• Planned concomitant systemic anti-tumor therapy during intraperitoneal treatment;
• Massive ascites not expected to be adequately drained prior to dosing;
• Chemotherapy or radiotherapy within 4 weeks prior to enrollment (≥ 6 weeks for nitrosoureas or mitomycin C);
• Pregnancy or lactation, or unwillingness to use effective contraception;
• Severe abdominal infection or gastrointestinal obstruction;
• Known peritoneal adhesions deemed unsuitable for catheter placement;
• Active bleeding, uncorrected coagulation disorders, or inability to safely interrupt therapeutic anticoagulation;
• Known hypersensitivity to PX, nab-paclitaxel, or excipients;
• Pre-existing ≥ Grade 2 peripheral sensory neuropathy;
• Severe or uncontrolled comorbidities that may increase study risk or interfere with evaluation;
• Active or severe autoimmune disease, or ongoing systemic immunosuppressive therapy;
• Positive for HBsAg, anti-HCV, syphilis antibody, or HIV antibody;
• Psychiatric or cognitive disorders affecting compliance;
• Any other condition deemed unsuitable by the investigator.