• Number of Subjects with treatment-related adverse events (AEs) [ Time Frame: 12 months ]
  Incidence, nature, and severity of adverse events graded according to the NCI CTCAE v5.0. AEs were considered to be treatment-related if they had started or worsened within the interval from first study drug administration until the follow-up visit.
• Progression-free survival (PFS) at 6 months [ Time Frame: 6 months ]
  Progression free survival (PFS) at 6 months in patients with local advanced /metastatic BTCs treated with the combined regimen. Progression will be defined clinically or on imaging as per immune related response evaluation criteria in solid tumors (RECIST V1.1) definition

• Disease control rate (DCR) [ Time Frame: 12 months ]
  DCR is defined as the proportion of subjects who achieved a stable disease (SD), partial response (PR) or complete response (CR) according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
• Object response rate (ORR) [ Time Frame: 12 months ]
  ORR is defined as the proportion of subjects who achieved a partial response (PR) or complete response (CR) according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
• Overall survival (OS) [ Time Frame: 24 months ]
  OS time was measured from the study entry to the date of death.
• Number of participants with laboratory test abnormalities [ Time Frame: 12 months ]
  The laboratory tests of serum cytokines and chemokines will be performed on day 1 and 3 of each cycle, and the abnormality will be determined by the investigator.

• Drug: Manganese Chloride
  Administered by inhalation at 0.2 or 0.4mg/kg/d once daily in a 3-week cycle
• Drug: nab-paclitaxel
  Administered intravenously, 125mg/m2/d on day1 and day8 in a 3-week cycle
  Other Name: Paclitaxel For Injection (Albumin Bound)
• Drug: Gemcitabine
  Administered intravenously, 1g/m2/d on day1 and day8 in a 3-week cycle
• Drug: anti-PD-1 antibody
  Administered intravenously, 2-4mg/kg on day 3 in a 3-week cycle
  Other Name: Anti-PD-1 monoclonal antibody; PD-1 inhibitor

Inclusion Criteria:

1. ≥ 18 years old.
2. Life expectancy of at least 3 months.
3. Subjects must have Histopathological/cytological diagnosis of unresectable or recurrent /metastatic biliary tract carcinoma (intra-hepatic, extrahepatic or gall bladder).
4. Eastern Cooperative Oncology Group performance status 0-2.
5. Subjects must have at least one measurable lesion ≥ 1 cm as defined by response criteria.
6. Subjects may have received prior radiotherapy, chemotherapy, or other local ablative therapies, which completed ≥ 4 weeks prior to registration AND patient has recovered to <= grade 1 toxicity.
7. Subjects with Anti-PD-1 antibody treatment history are eligible which must be resistance.
8. Adequate organ function.
9. Participants of childbearing potential must be willing to use an adequate method of contraception for the course of the study through 120 days after the last dose of study drug.

Exclusion Criteria:

1. Subjects with any autoimmune disease or history of syndrome that requires corticosteroids or immunosuppressive medications.
2. Serious uncontrolled medical disorders or active infections, pulmonary infection especially.
3. Prior organ allograft.
4. Women who are pregnant or breastfeeding.
5. Women with a positive pregnancy test on enrollment or prior to investigational product administration.
6. Subjects who are compulsorily detained for treatment of either a psychiatric or physical (eg, infectious disease) illness.