Further study needed
Ott said there is already one type of cancer vaccine, for prostate cancer, on the market, but it is not widely used.
Another, for lung, bladder, and skin cancer, is undergoing a Phase II efficacy trial, in combination with another drug.
"We've long recognised in cancer that every patient's tumour is different," the team said in a statement.
"With recent advances in technology, it's now becoming possible to create a therapy that's suited to target an individual's tumour."
The NeoVax treatment contained up to 20 neoantigens derived from patient tumours.
The researchers sequenced the DNA of tumour cells and healthy cells from each person to identify cancer-specific mutations and pinpoint the neoantigens involved.
The patients had their immune systems "trained" to recognise these molecules, with the goal of stimulating an attack.
In a second study published in the same journal, a team tested another personalised vaccine on 13 people with melanoma.
This vaccine was similarly safe and induced an immune response, they concluded.
"The two studies confirm the potential of this type of approach," Cornelis Melief of the Leiden University Medical Center in the Netherlands wrote in a comment.
Next-phase trials in larger groups of participants are now needed, he said, "to establish the efficacy of these vaccines."