This is a phase III， Multicenter, Randomized study， evaluating the efficacy and Safety of LM-108(an Anti-CCR8 mAb) in combination With Toripalimab Versus Paclitaxel Injection in subjects with CCR8-Positive locally advanced or metastatic Gastric Cancer and Gastroesophageal Junction Adenocarcinoma.

Inclusion Criteria:

1. Individuals who are willing to participate in the study and sign the informed consent form (ICF) prior to any procedure.
2. Age 18 years or older, male or female.
3. Weight ≥ 40 kg or Body Mass Index (BMI)≥ 18.5 kg/m²
4. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
5. Life expectancy ≥ 3 months.
6. Individuals must have histologically or cytologically confirmed locally advanced or metastatic gastric/gastroesophageal junction adenocarcinoma and be ineligible for curative surgery or radiotherapy.
7. Confirmed CCR8-positive by the central laboratory.
8. HER2-negative, low-expressing, or non-expressing.
9. Individuals must experience radiographic progression during or after prior standard first-line therapy, or who developed intolerance to treatment due to chemotherapy-related toxicity
10. At least one lesion.
11. Have appropriate organ and marrow function in laboratory examinations.
12. Women of childbearing potential have a negative pregnancy test and must not be breastfeeding. All of reproductive potential agree to use effective contraception throughout the study period and for 6 months after the last dose of study drug.

Exclusion Criteria:

1. Received treatment targeting the same target or other drugs acting on regulatory T cells (Tregs).
2. Received antitumor treatments such as chemotherapy, radiotherapy, biological therapy, immunotherapy, or Chinese herbal medicine or Chinese herbal preparations within 2-4 weeks (depending on the specific anticancer drug) prior to the first dose.
3. Received anti-PD-(L)1 antibody immunotherapy and experienced disease progression confirmed by RECIST 1.1 assessment within ≤2 months after treatment initiation.
4. Use of any live vaccine within 4 weeks prior to the first dosing of study drugs.
5. Individuals who received major surgery or interventional treatment within 4 weeks prior to the first dosing of study drugs.
6. Individuals who take systemic corticosteroids (> 10 mg daily prednisone equivalents) or other systemic immunosuppressive medications within 2 weeks prior to the first dosing of study drugs.
7. Any adverse event from prior anti-tumor therapy has not yet recovered to ≤ grade 1 of CTCAE v6.0, individuals who experienced ≥ Grade 3 immune-related adverse events during prior immunotherapy, or terminated prior immunotherapy due to severe or life-threatening immune-related adverse events.
8. Any other pathological type.
9. Uncontrollable clinical third-space fluid accumulation.
10. Unstable or progressive central nervous system (CNS) metastases or carcinomatous meningitis (meningeal metastases).
11. Individuals with a known history of autoimmune diseases.
12. For individuals with drug allergies or contraindications.
13. The investigator determined that there are other situations that are not suitable for participation in this study.