A small early trial of a personalized cancer vaccine has produced a striking result. All 16 patients who got the vaccine, called TG4050, right after their usual treatment stayed free of cancer for more than three years, the Clatterbridge Cancer Centre in England said Tuesday. In a comparison group of 16 patients who were watched without the vaccine, cancer came back in three.

The patients had a type of head and neck cancer not linked to HPV, and surgeons had already removed their tumors. The median follow-up was 41 months, drugmaker Transgene said.

Each vaccine is built for one person. Scientists read the tumor's genes, and AI tools from Japan's NEC pick up to 30 features found only on that patient's cancer. The vaccine then teaches the immune system to spot and attack cells that carry those features. A weakened virus carries the instructions into the body.

Almost three in four vaccinated patients, 73.3%, built an immune response against their own cancer. Those responses lasted more than a year after the last dose. No unexpected safety problems turned up. The full results appeared in the journal Nature Communications.

"These results are very encouraging," said Prof. Christian Ottensmeier, who leads the trial in the UK. "This was a small, early study, so the larger Phase 2 trial is vital."

How the trial worked: half the patients got the vaccine right after treatment. The other half got it only if their cancer came back, as an added treatment, Transgene said.

The backstory: Clatterbridge became the first UK site to give the vaccine to a patient, in February 2022. It enrolled the first two UK patients in the Phase 2 study in November 2024. That larger international trial is testing whether the vaccine can keep cancer from returning. Transgene expects its first two-year results by early 2028.

What we know: All 16 vaccinated patients stayed cancer-free past three years, compared with 13 of 16 in the comparison group.
What we don't: Whether the result holds up in the larger Phase 2 trial.