Personalized Neoantigen Peptide Vaccine Shows Promising Response in Chemotherapy-Resistant Ovarian Cancer Patient | Research

The takeaway

A personalized dendritic cell vaccine loaded with four neoantigen peptides reduced the cancer marker CA-125, decreased tumor cells in abdominal fluid, and generated tumor-specific T cells in a patient with treatment-resistant ovarian cancer.

Neoantigen-specific TCRs in tumor
After vaccination, T cell receptors specifically recognizing the mutated PPM1F neoantigen were detected within the patient's tumor — proof that the vaccine directed cancer-fighting immune cells to the right target.

What the researchers found

After four rounds of intranodal vaccination with neoantigen peptide-loaded dendritic cells, the patient experienced: remarkable decline in CA-125 levels (ovarian cancer marker), decreased tumor cells in malignant ascites, and improvement in tumor-related symptoms including respiratory discomfort — all without adverse reactions.

Immunologically, the vaccine generated a detectable T cell response against an HLA-A2402-restricted neoantigen peptide derived from mutated PPM1F protein, confirmed by IFN-γ ELISPOT assay. Critically, neoantigen-specific T cell receptors (TCRs) were detected in tumor-infiltrating lymphocytes post-vaccination, demonstrating the vaccine successfully directed immune cells into the tumor.

Why it matters

Chemotherapy-resistant ovarian cancer has very few treatment options and is often fatal. This case demonstrates that personalized neoantigen peptide vaccines can produce both meaningful clinical improvements and measurable immune responses even in heavily pre-treated patients. The detection of neoantigen-specific T cells within the tumor is particularly encouraging, as it shows the vaccine is directing immune cells to where they're needed most.

The numbers in context

1 patient; 4 neoantigen peptides; 4 vaccine rounds; CA-125 declined; ascites cells decreased; HLA-A2402 restricted PPM1F neoantigen; TCRs in tumor

How the study worked

This is a single-patient case report. Neoantigens were identified using an immunogenomic pipeline (whole exome sequencing). Four neoantigen peptides were selected and loaded onto the patient's autologous dendritic cells. The vaccine was administered via ultrasound-guided intranodal injection over four rounds. Clinical response was monitored by CA-125 levels and ascites analysis. Immune response was assessed by IFN-γ ELISPOT assay on peripheral blood lymphocytes and TCR analysis of tumor-infiltrating lymphocytes.

Who was studied

71-year-old female with chemorefractory ovarian cancer and malignant ascites

What this study cannot tell us

This is a single case report, which cannot prove causation — spontaneous disease fluctuations in ovarian cancer are possible. No control group for comparison. Long-term outcomes are not reported. The immunogenomic pipeline's peptide selection success rate (1 of 4 peptides generated detectable responses) suggests room for improvement in neoantigen prediction. Generalizability to other patients is unknown.

How to read the evidence

This is a single-patient case report, which provides the lowest level of clinical evidence. While the concordant clinical and immunological responses are encouraging, a single case cannot establish efficacy. Larger controlled trials would be needed to confirm these findings.

When this study was published

Published in 2021, this case report is part of the growing body of early clinical evidence for personalized neoantigen cancer vaccines. The field has continued to advance rapidly since, with several larger trials underway.

The bigger picture

Personalized cancer vaccines based on tumor-specific neoantigens are one of the most exciting developments in oncology. While mRNA-based platforms have gained attention, this study shows that peptide-loaded dendritic cell vaccines can also generate meaningful clinical and immune responses. The intranodal delivery route and the demonstration of tumor-infiltrating neoantigen-specific T cells add practical insights for the growing field of personalized cancer immunotherapy.

Questions still open

Would this neoantigen DC vaccine approach show consistent responses in a larger cohort of chemorefractory ovarian cancer patients?
Could combining this personalized vaccine with checkpoint inhibitors further enhance the anti-tumor immune response?
What factors determine which predicted neoantigen peptides successfully generate T cell responses versus those that don't?

Common questions

What is a personalized neoantigen cancer vaccine?

It's a vaccine custom-made for each patient by sequencing their tumor's DNA to find unique mutations (neoantigens), then training their own immune cells to recognize those mutations. This patient received dendritic cells loaded with four peptides specific to her cancer's mutations.

Can this type of vaccine help when chemotherapy stops working?

In this case, yes — a patient whose ovarian cancer no longer responded to chemotherapy saw her cancer marker decline, tumor cells decrease, and symptoms improve after receiving a personalized neoantigen vaccine. However, this is a single case and larger studies are needed to confirm the approach works consistently.

Read the original research

Intranodal Administration of Neoantigen Peptide-loaded Dendritic Cell Vaccine Elicits Epitope-specific T Cell Responses and Clinical Effects in a Patient with Chemorefractory Ovarian Cancer with Malignant Ascites.

Immunological investigations, 50(5), 562-579

View on PubMed ↗Publisher’s paper ↗

Citation

Morisaki, Takashi; Hikichi, Tetsuro; Onishi, Hideya; Morisaki, Takafumi; Kubo, Makoto; Hirano, Tatsuya; Yoshimura, Sachiko; Kiyotani, Kazuma; Nakamura, Yusuke. (2021). Intranodal Administration of Neoantigen Peptide-loaded Dendritic Cell Vaccine Elicits Epitope-specific T Cell Responses and Clinical Effects in a Patient with Chemorefractory Ovarian Cancer with Malignant Ascites.. Immunological investigations, 50(5), 562-579. https://doi.org/10.1080/08820139.2020.1778721