What are neoantigen vaccines and how do they work?
Neoantigen vaccines are personalized cancer treatments that train a patient's immune system to attack their specific tumor. Unlike standard vaccines that target shared antigens, neoantigens are unique protein fragments created by mutations in a person's cancer cells [7][9]. Because these neoantigens are not present on normal cells, the immune system can recognize them as foreign and mount a powerful, targeted attack without harming healthy tissue [7].
The process starts with sequencing the patient's tumor DNA to identify mutations, then using computer algorithms to predict which mutations will generate strong immune responses [9]. A custom vaccine is then manufactured—often as a peptide, mRNA, or DNA formulation—and injected into the patient. The vaccine delivers these neoantigens to antigen-presenting cells, which activate T cells that can seek out and destroy cancer cells [1][3][5]. This approach is highly individualized: each patient receives a vaccine tailored to their tumor's unique genetic profile.
What does the clinical evidence show so far?
The most compelling data come from two recent trials. In a 2023 phase 1 trial of 16 patients with pancreatic cancer, an mRNA neoantigen vaccine (autogene cevumeran) induced strong T cell responses in half of the patients (8 out of 16). Those responders had a median recurrence-free survival that was not reached at 18-month follow-up, compared to 13.4 months for non-responders—a statistically significant difference [1]. This suggests the vaccine may delay cancer recurrence in patients who mount an immune response.
In a 2024 phase 1/2 trial of 36 patients with advanced liver cancer (hepatocellular carcinoma), a DNA neoantigen vaccine (GNOS-PV02) combined with the immune checkpoint inhibitor pembrolizumab produced an objective response rate of 30.6% (11 of 36 patients), including 3 complete responses [3]. Importantly, 86.4% of evaluable patients (19 of 22) showed neoantigen-specific T cell responses, and the vaccine was well-tolerated with no serious treatment-related side effects [3]. These results are encouraging, but the trial was small and single-arm, so larger randomized studies are needed.
However, the field is still early. A 2024 analysis of 199 neoantigen vaccine clinical trials found that 59.8% (119 trials) were phase 1 studies, and only a handful had progressed to later phases [2]. Another review noted that despite over 100 clinical trials, proof of unequivocal efficacy has remained beyond reach for the majority [10]. So while the early signals are positive, the evidence base is not yet strong enough to recommend these vaccines as standard therapy.
What are the main challenges to clinical translation?
Several hurdles remain before neoantigen vaccines can become widely available. First, manufacturing a personalized vaccine for each patient is complex and time-consuming. In the pancreatic cancer trial, vaccines were synthesized in real time from surgically resected tumors and administered within 3 days of benchmarked times, which is feasible but logistically demanding [1]. Scaling this up for routine use would require significant infrastructure.
Second, not all patients respond. In the pancreatic cancer trial, only 50% of patients developed vaccine-induced T cells [1]. The reasons for non-response are not fully understood but may involve the tumor's immune-suppressive environment or the patient's immune fitness [10]. The liver cancer trial had a higher response rate (86.4% showed T cell responses), but the clinical response rate was still only 30.6% [3]. Improving response rates is a key goal.
Third, combination strategies are critical. Both successful trials combined the vaccine with other treatments—chemotherapy and an immune checkpoint inhibitor in the pancreatic cancer trial [1], and an immune checkpoint inhibitor in the liver cancer trial [3]. A 2022 review of 147 trials found that neoantigen vaccines work best when combined with other therapies, such as immune checkpoint inhibitors, chemotherapy, or radiation [4]. Determining the optimal timing, sequencing, and combination partners is an active area of research [6].
Finally, delivery systems are evolving. Peptide vaccines have been the most common type (64.8% of trials up to 2022), but mRNA and DNA platforms are growing rapidly due to their flexibility and speed [2][4]. Newer approaches, such as using engineered bacterial carriers or virus-like particles, aim to improve antigen delivery and immune activation [5][8]. These innovations may help overcome current limitations, but they are still in preclinical or early clinical stages.
About These Sources
This answer is built on 10 peer-reviewed studies — published from 2022 to 2026, 4 from 2024 or later, 8 in Q1 journals, collectively cited 2,916 times — selected as the most relevant from 10 studies that passed quality screening, drawn from 58 papers retrieved from a database of over 500 million.
Sources used in this answer
Personalized RNA neoantigen vaccines stimulate T cells in pancreatic cancer
In a phase 1 trial of 16 pancreatic cancer patients, an mRNA neoantigen vaccine induced T cell responses in 50% of patients; responders had longer recurrence-free survival (not reached at 18 months) vs. 13.4 months for non-responders.
Personalized neoantigen cancer vaccines: current progression, challenges and a bright future
A 2024 analysis of 199 neoantigen vaccine clinical trials found 59.8% were phase 1, with peptide vaccines being the most common type (64.8%), and a shift toward liposomal and DC platforms.
Personalized neoantigen vaccine and pembrolizumab in advanced hepatocellular carcinoma: a phase 1/2 trial
In a phase 1/2 trial of 36 advanced liver cancer patients, a DNA neoantigen vaccine plus pembrolizumab produced a 30.6% objective response rate, with 86.4% of evaluable patients showing T cell responses.
Neoantigen Vaccines; Clinical Trials, Classes, Indications, Adjuvants and Combinatorial Treatments
A 2022 systematic analysis of 147 neoantigen vaccine trials found peptide vaccines were most common (41%), and combination with immune checkpoint inhibitors, chemotherapy, or radiation was common.
Reinforcing cancer immunotherapy with engineered porous hollow mycobacterium tuberculosis loaded with tumor neoantigens
Preclinical study showing that engineered porous hollow Mycobacterium tuberculosis carriers can enhance dendritic cell uptake of neoantigens and improve anti-tumor immunity in mouse models.
Bridging clinical gaps in personalized cancer neoantigen vaccines.
A 2026 review discusses key translational opportunities and challenges for personalized neoantigen vaccines, including optimal tumor indications, timing, and combinatorial regimens.
Neoantigens: promising targets for cancer therapy
A 2023 review outlines neoantigen identification methods and clinical applications, emphasizing their high immunogenicity and tumor specificity as targets for personalized immunotherapy.
Caveolin-mediated cytosolic delivery of spike nanoparticle enhances antitumor immunity of neoantigen vaccine for hepatocellular carcinoma
Preclinical study showing that virus-like silicon nanoparticles with spike structures can co-deliver neoantigen and TLR9 agonist to dendritic cells, improving CD8+ T cell responses in liver cancer models.
Identification of neoantigens for individualized therapeutic cancer vaccines
A 2022 review describes computational tools for neoantigen discovery and introduces a classification of neoantigens (guarding, restrained, ignored) based on their clinical context.
Challenges in developing personalized neoantigen cancer vaccines
A 2023 review highlights key obstacles to neoantigen vaccine efficacy, including vaccine design and tumor microenvironment challenges, noting that unequivocal efficacy remains unproven in most trials.