Researchers have reported the first results from a small trial that gave women with a hard-to-treat form of ovarian cancer a vaccine built just for them, from the mutations in their own tumors. The vaccine, called NeoVax, triggered a targeted immune response in 8 of the 10 women who received it, and it also left behind long-lasting immune cells in the blood that could recognize the tumor mutations1. The results were published in the journal Nature Medicine1, listed on October 14, 20262.
The trial was a Phase 1 study, the first and smallest stage of testing in people, which mainly asks whether a treatment can be made and given safely1. It was not designed to show whether the vaccine helps women live longer or keeps the cancer from coming back.
What the researchers did
When cancer cells divide quickly, they can pick up DNA mutations. Some of these mutations produce abnormal proteins, called neoantigens, that are unique to each patient’s cancer1. The idea behind a personalized vaccine is to show the immune system these abnormal proteins so it learns to attack cells carrying them, especially the immune cells called T cells1.
The team read the DNA and RNA of both cancer cells and healthy cells from each patient to find her neoantigens1. They took tumor samples before treatment and healthy blood samples, then used a method called whole-exome sequencing, which reads the parts of the genes that make proteins, to find mutations found only in the tumor1.
From those mutations, they made short synthetic protein chains, each 15 to 33 building blocks (amino acids) long1. These were split into four personalized injection pools and mixed with poly-ICLC, an ingredient that acts as an alarm signal to immune cells at the injection site1.
All patients first finished standard platinum-based chemotherapy before vaccination began1. The plan was to give the vaccines right after chemotherapy, when the amount of tumor left in the body is at its lowest1. Patients later also received nivolumab (sold as Opdivo), an anti-PD-1 antibody, a type of drug that helps immune cells attack cancer1.
What the trial found
The team enrolled 22 patients: 9 who were newly diagnosed and 13 whose cancer had come back. Only 10 went on to be vaccinated1. A summary of the paper’s abstract says nine of the vaccinated patients had cancer that had come back2.
- Making the vaccines: the researchers were able to manufacture personalized vaccines and give them alongside standard chemotherapy and immunotherapy1.
- Safety: all 10 vaccinated women completed treatment without having to stop because of toxic side effects1. The abstract summary says no unexpected safety issues were seen2.
- Immune response: 8 of the 10 vaccinated patients showed a targeted immune response, and long-lasting T cells that recognized the tumor mutations appeared in the blood1.
- Targets still present: even though a median of 6.5 months passed between the first tumor sample and vaccination, more than 70% of the targeted mutations could still be detected in the blood1.
On the cancer itself, the picture was mixed. Blood-marker tests suggested the treatment may have been biologically active in six patients12. Of those, three had temporary disease control and three had more lasting control, while four patients had tumors that kept growing without a pause1. Patients whose cancer stayed under control had immune responses against a wider range of the targeted mutations than patients whose cancer kept growing1.
For patients who had tumor samples taken after vaccination, the team also checked whether the vaccine-trained T cells recognized the patient’s actual tumor cells1.
What it does not show yet
This was a very small study. Only 10 women received the vaccine, out of 22 who signed up1. Every vaccinated patient also received nivolumab1, and the reports describe no group that got the immune drug without the vaccine. That makes it impossible to tell how much of any effect came from the vaccine itself.
An immune response measured in blood is not the same as a patient benefit. The trial’s own results show this gap: most women had an immune response, yet the cancer kept growing in four of the ten1. The link between broader immune responses and disease control is an association in a handful of people, not proof that the vaccine caused the control1.
The researchers themselves say future trials will need to study how tumors become resistant to treatment, to work out how a vaccine’s effect can be shown in hard-to-treat cancers like this one1.
Why this cancer is hard to treat
About 80% of epithelial ovarian cancers are the high-grade serous type, which carries mutations in a gene called TP531. These tumors often hold back immune attacks and have relatively few mutations for the immune system to recognize. As a result, standard immunotherapy drugs that work well in some other cancers help fewer than 10% of these patients1. The cancer also often returns after the first round of treatment, which is the problem the vaccine was meant to address1.
Who is behind it
The study was published in Nature Medicine, a peer-reviewed journal12. The sources available to Biohack do not say who funded the trial, which institutions ran it, or whether any authors have ties to companies that could make such vaccines. Readers should treat those questions as open until the full paper’s funding and conflict-of-interest statements are checked.
How it fits the field
Personalized vaccines for ovarian cancer have been tried before in other forms. A 2018 pilot trial published in Science Translational Medicine used a patient’s own immune cells (dendritic cells) loaded with material from her whole tumor, in women whose ovarian cancer had come back after platinum chemotherapy3. Across three groups of 5, 10 and 10 patients, 392 doses were given without serious side effects, and immune responses to the tumor were associated with longer survival3. That vaccine also boosted T cells against mutation-based targets3.
Other approaches in ovarian cancer aim at shared targets rather than each patient’s own mutations. A Mayo Clinic early trial tested a dendritic cell vaccine aimed at folate receptor alpha, a protein often found in large amounts on ovarian cancer cells4. A Georgetown University trial paired a vaccine aimed at a protein called NY-ESO-1 with nivolumab in women whose cancer no longer responded to platinum therapy5. Both listings say the trials are no longer recruiting45.
Beyond ovarian cancer, a market research report lists a pipeline of cancer vaccines, including one from Merck and Moderna paired with Keytruda6, and notes that personalized mutation-based vaccines have been shown to be feasible, safe and able to stir the immune system in patients with melanoma and glioblastoma, a brain cancer6. A separate first-in-people trial of a personalized implanted vaccine in 21 people with advanced melanoma reported stable disease in 43% of patients7.
What to watch next
The researchers suggest personalized vaccines may have the greatest impact when given together with first-line treatment, while the amount of cancer left in the body is at its lowest1. In this trial, most vaccinated women had cancer that had already come back2. Key questions for any follow-up trial are whether more newly diagnosed women can be vaccinated in time, whether a larger study with a comparison group shows that the vaccine adds anything to standard care, and how tumors escape the immune attack1.
