KRAS Neoantigen Nanovaccine as Adjuvant Therapy for Colorectal Cancer/Pancreatic Cancer

This clinical trial will utilize a neoantigen nanovaccine constructed from the bacterial membranes of an engineered Lactococcus lactis strain (FOLactis). This platform, independently developed by our center, expresses KRAS antigenic peptides. The vaccine will be administered as adjuvant therapy to post-operative patients with colorectal or pancreatic cancer who carry KRAS mutations and are at high risk of recurrence. The study aims to assess the safety, immunogenicity, and preliminary efficacy of this neoantigen nanovaccine in a clinical setting.

1. Pre-vaccination Screening: Detection of KRAS hotspot mutations in the patient's tumor tissue. 2. Vaccine Composition and Administration: The vaccine utilizes a neoantigen nanovaccine constructed from the bacterial membranes of engineered Lactococcus lactis, independently developed by the Cancer Center of Nanjing Drum Tower Hospital. It is administered via subcutaneous or intralymph node injection. The study consists of two phases: Dose Escalation and Dose Expansion. The Dose Escalation phase involves the vaccine alone, while the Dose Expansion phase combines the vaccine with anti-PD-1 antibody and anti-CTLA-4 antibody, as detailed below: Dose Escalation Phase: Conducted according to a "3+3" design. The neoantigen nanovaccine is tested at two dose levels: 1.5mg and 3.0mg. Each injection has a total volume of 2.0ml, administered subcutaneously or via ultrasound-guided injection into bilateral inguinal lymph nodes. Vaccination Schedule: A total of 9 vaccinations are planned on Days 1, 4, 8, 15, 22, 43, 64, 85, and 106. Vaccinations #1 and #5-#9: Ultrasound-guided bilateral inguinal lymph node injection combined with subcutaneous injection in the subdeltoid region,accompanied by intravenous cyclophosphamide (200mg/m²) on the same day. Vaccinations #2, #3, and #4: Subcutaneous injection. Efficacy and Safety Monitoring: Radiographic efficacy evaluations are performed every 12 weeks for the first two years post-surgery, and every 24 weeks thereafter. Adverse events are assessed following each vaccination. Dose Expansion Phase: The vaccine dose for this phase is determined based on results from the Dose Escalation phase. The vaccination procedure remains the same. Twenty eligible post-operative colorectal cancer patients and twenty eligible post-operative pancreatic cancer patients will be enrolled for continued observation of efficacy and side effects. The nanovaccination schedule follows the Dose Escalation phase protocol. The anti-CTLA-4 antibody is administered on D1 and D43. The anti-PD-1 antibody is administered starting on the first day of vaccination, once every three weeks, until disease progression, unacceptable toxicity, or completion of 6 cycles, whichever occurs first. 3. Immunological Follow-up: Hematological immune monitoring, including lymphocyte immunophenotyping and cytokine profiling, is performed pre-vaccination and on Days 1, 22, 43, 85, and 106 after the first vaccination.

Drug: KRAS Neoantigen Nanovaccine. The vaccine utilizes a neoantigen nanovaccine constructed from the bacterial membranes of engineered Lactococcus lactis, independently developed by the Cancer Center of Nanjing Drum Tower Hospital. It is administered via subcutaneous or intralymph node injection.

Experimental Group (experimental): neoantigen nanovaccine constructed from the bacterial membranes of engineered Lactococcus lactis, independently developed by the Cancer Center of Nanjing Drum Tower Hospital. It is administered via subcutaneous or intralymph node injection.

Dose-limiting toxicities (DLT). Time frame: From clinical trial enrollment until the date of first documented progression or date of death from any cause, whichever came first, assessed up to five years..

Proportion of patients with a decrease in positive tumor markers (ctDNA and/or CEA/CA199). Time frame: 3 months post-first vaccination.

Proportion of patients with clearance of positive tumor markers (ctDNA and/or CEA/CA199). Time frame: 3 months post-first vaccination.

KRAS neoantigen specific T cells. Time frame: From clinical trial enrollment until the date of first documented progression or date of death from any cause, whichever came first, assessed up to five years..

Recurrence-free survival (RFS). Time frame: From clinical trial enrollment until the date of first documented progression or date of death from any cause, whichever came first, assessed up to five years..

Correlation between neoantigen-specific T-cell frequency and dynamic changes in tumor markers (ctDNA and/or CEA/CA199). Time frame: From clinical trial enrollment until the date of first documented progression or date of death from any cause, whichever came first, assessed up to five years..

Association between neoantigen-specific T-cell frequency and recurrence-free survival (RFS). Time frame: From the date of surgery/treatment initiation to the date of first documented disease recurrence or death from any cause. Assessment will be based on radiographic evaluation and clinical follow-up..

Inclusion Criteria: * Age ≥18 years and ≤75 years, with an ECOG performance status of 0-1. * Patients with histologically confirmed colorectal adenocarcinoma or pancreatic adenocarcinoma who have undergone radical resection (R0) and completed at least 4 cycles of postoperative adjuvant chemotherapy. * Postoperative pathological stage for colorectal cancer is IIIA, IIIB, or IIIC. For pancreatic cancer, postoperative pathological stage is I, II, or III. The tumor must harbor at least one of the following KRAS hotspot mutations: G12D, G12V, G12R, G12A, G12S, G12C, or G13D. * No radiological evidence of tumor recurrence or metastasis. * Patients must meet the following hematologic criteria: Lymphocyte count ≥0.5×10⁹/L, neutrophil count ≥1.5×10⁹/L, white blood cell count \>2.5×10⁹/L; Hemoglobin ≥90 g/L; Platelet count ≥90×10⁹/L. * Patients must meet the following biochemical criteria: Total bilirubin ≤1.5 × upper limit of normal (ULN); AST and ALT ≤1.5 × ULN; Serum creatinine ≤1.5 × ULN or creatinine clearance ≥30 mL/min. * Patients must meet the following coagulation criteria: INR or PTT ≤1.5 × ULN. * Patients of childbearing potential must employ adequate contraception or other birth control methods before enrollment and throughout the trial. * Signed informed consent form has been obtained. * Ability to comply with the study protocol and follow-up procedures. Exclusion Criteria: * Patients with colorectal cancer exhibiting microsatellite instability-high (MSI-H)/deficient mismatch repair (dMMR) or harboring BRAF mutations. * Pancreatic cancer patients with neuroendocrine tumor components are excluded. * Patients with a history of other malignancies, except for carcinoma in situ of the cervix, treated squamous cell carcinoma or bladder epithelial tumors (Ta and TIS), or other malignancies that have been curatively treated (at least 5 years prior to enrollment). * Prior treatment with anticancer vaccines or any antibodies targeting T-cell co-regulatory proteins (e.g., anti-PD1, anti-PDL1, or anti-CTLA4). * Patients with HIV, HCV, or HBV infection; uncontrolled coronary artery disease or asthma; uncontrolled cerebrovascular disease; or any other condition deemed by the investigator as grounds for exclusion. * Patients who are on immunosuppressants or systemic corticosteroid therapy for immunosuppressive purposes (at a dose \>10 mg/day prednisone or equivalent) and have continued use within 2 weeks prior to enrollment. * Poorly controlled cardiac clinical …

Enrollment: 49 participants (estimated).