Abstract
The clinical advancement of mutant KRAS and tailored neoantigen vaccines in pancreatic ductal adenocarcinoma necessitates a clear differentiation between biological activity and patient benefit. This critical narrative review synthesizes chosen primary research with literature on immune-assays, biomarkers, and clinical trial methodologies to suggest a framework for endpoints and design. Five interrelated assertions are identified: strategy deliverability, antigen-specific immune induction, tumor engagement, molecular disease alteration, and patient advantage; safety and treatment burden are relevant to all five. The framework distinguishes a vaccine-strategy question beginning before individualized manufacture from a vaccine-ready question conditional on product availability and reconfirmed clinical eligibility. The suitable inquiry is contingent upon the aim of the trial. The framework also distinguishes the time origins of clinical follow-up and biological evaluations, maintains distinct categories for enrolled, vaccinated, and immune-evaluable populations, and separates missing measurements from clinical events. Assay positivity, reactivity to tumor-matched peptides, recognition of naturally processed tumor antigens, clonal persistence, circulating tumor DNA clearance, and enhanced survival are regarded as separate outcomes. Setting-specific designs address perioperative, molecular-residual-disease, advanced-disease, and cancer-interception populations. Landmark analyses are beneficial but inadequate for determining a causal vaccination impact through responder comparisons. Original design tables and a suggested reporting checklist convert these concepts into prospective trial-design decisions. The framework is an unvalidated methodological proposal, rather than a systematic review, pooled efficacy analysis, or consensus guideline; its value requires prospective evaluation.