Locally Advanced Gastric Adenocarcinoma

This phase I/II trial tests the safety and tolerability of an experimental personalized vaccine when given by itself and with pembrolizumab in treating patients with solid tumor cancers that have spread to other places in the body (advanced). The experimental vaccine is designed target certain proteins (neoantigens) on individuals' tumor cells. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving the personalized neoantigen peptide-based vaccine with pembrolizumab may be safe and effective in treating patients with advanced solid tumors.

This phase I trial tests the safety, side effects and best dose of futibatinib with paclitaxel and ramucirumab for the treatment of patients with gastric, gastroesophageal junction or esophageal adenocarcinoma that has spread to nearby tissue or lymph nodes (locally advanced) or that cannot be removed by surgery (unresectable). Futibatinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Paclitaxel is in a class of medications called antimicrotubule agents. It stops cancer cells from growing and dividing and may kill them. Ramucirumab is a monoclonal antibody that may prevent the growth of new blood vessels that tumors need to grow. Giving futibatinib with paclitaxel and ramucirumab may be safe and tolerable in treating patients with locally advanced or unresectable gastric, gastroesophageal junction or esophageal adenocarcinoma.

The goal of this clinical trial is to learn if a new type of scan, FAPI-PET/CT, can help find metastases of gastric cancer. We want to know how well this scan works for this purpose and whether it is less burdensome for patients compared to the methods we currently use to find metastases. The main questions it aims to answer are: * In how many patients can FAPI-PET/CT find metastases, which leads to a change in their treatment plan as decided by their medical team, such as avoiding unnecessary surgeries and changing from treatment meant to cure the disease to treatment focused on comfort (palliative treatment)? * In how many patients does FAPI-PET/CT change the diagnostic process as decided by their medical team, like more biopsies or imaging, or changing the type (extent) of surgery needed? Apart from the usual care gastric cancer patients receive, participants will: * Undergo one additional scan, which will take approximately 2 hours in total (excluding travel time) * Complete a number of questionnaires, which will take approximately 4 hours in total

A phase II study of peri-operative anti-PD1 (Zimberelimab) +/- anti-TIGIT (Domvanalimab) in resectable mismatch repair deficient (MMRd)/ high micro-satellite instability (MSI-H) gastric/gastro-oesophageal junctional (GOJ) adenocarcinoma (AC)

The goal of this single arm clinical trial is to learn about sequential S-1 adjuvant therapy in patient wich locally advanced gastric cancer. The main question it aims to answer is: • The efficacy and safety of S-1 adjuvant therapy, following D2 radical surgery and DS(Docetaxel + S-1) adjuvant chemotherapy. All patients with locally advanced gastric cancer will received D2 radical surgery, 6 cycles of DS chemotherapy, and sequential S-1 chemotherapy up to 1 year postoperation.

The FOLFIRINOX regimen has become the standard treatment regimen for advanced colorectal cancer, advanced pancreatic cancer and postoperative adjuvant treatment for pancreatic cancer. With the continuous exploration of Chinese scholars, it has also revised the modified dose suitable for the physical fitness of the Chinese people, which is well tolerated and has a clear efficiency. The drugs in this program are all standard treatment drugs for gastric cancer. In 2020, JAMA Network Open and JAMA Oncology successively reported the application of FOLFIRINOX in the perioperative period of gastric cancer and the late-stage results of gastric cancer, and they obtained very amazing data respectively. According to the results of CheckMate-649, the FDA approved Nivolumab combined chemotherapy for first-line treatment of advanced or metastatic gastric cancer, gastroesophageal junction cancer and esophageal adenocarcinoma, regardless of PD-L1 expression. At the same time, this is also the first first-line immunotherapy approved by the FDA for gastric cancer.However, there is no definite conclusion about the preoperative neoadjuvant or perioperative clinical research, so it is necessary to explore the efficacy of PD-1 antibody in the perioperative period. This study is a single-center, randomized, controlled phase II clinical study. The primary endpoint of the study is the perioperative administration of mFOLFIRINOX regimen combined with PD-1 antibody and D2 radical resection for the treatment of resectable advanced gastric cancer. The deep tumor remission rate (TRG0 and TRG1) , secondary endpoints include pCR rate, 3-year DFS rate, safety, R0 resection rate, D2 radical resection rate, 5-year DFS rate, 5-year OS rate.