Cancer Vaccines, no longer science fiction
By Helena Strigård, CEO and Founder
October 1, 2026
After two decades as the idea that never quite worked, a personalised cancer vaccine has a randomised Phase 3 behind it. Researchers on what changed, what it will cost, and why the field now believes it can reach the tumours it never could.
For two decades the cancer vaccine occupied an awkward place in oncology: biologically plausible, clinically disappointing, almost challenging to finance. That changed on 19 August, when Moderna and Merck reported Phase 3 results in some 1,100 patients whose malignant melanoma had been surgically removed. Their individualised mRNA vaccine, given with the checkpoint inhibitor Keytruda, cut the risk of recurrence by 49 per cent against Keytruda alone, and the risk of spread to distant organs by 59 per cent. Moderna closed up 177 per cent that day.
"This is a completely new technology for treating cancer," says Matti Sällberg, professor of biomedical analysis at Karolinska Institutet, "and the first really good example that a personalised cancer vaccine can be made within a reasonable time."
What changed
The earlier generation of cancer vaccine trials mostly missed their endpoints. But in many of them a small number of patients did benefit, and the work of the past decade has been about understanding why those patients responded and others did not.
Two answers came out of that work, and the Moderna trial uses both. The first is knowing what to aim at: which of a tumour's mutations the immune system will actually recognise. That is easiest where there are many to choose from, which is why melanoma came first. It is a cancer that mutates a great deal, and, as Sällberg puts it, relatively easier to treat than many others.
The second answer is less comfortable, because it means a vaccine that provokes a textbook immune response can still lose. The tumour fights back, suppressing and counteracting the immune attack the vaccine sets off. Combining the vaccine with a checkpoint inhibitor is designed to address exactly that.
Which is where the week's other result comes in. Within days, BioNTech terminated a trial using comparable technology in microsatellite-stable (MSS) colorectal cancer, given alone without checkpoint blockade in a tumour that carries few mutations to begin with. The immunological data have not been published, so any interpretation is speculative. But MSS tumours generally harbour fewer of the private, mutation-derived targets a personalised vaccine relies on, and may depend more on recurrent antigens shared across patients, which is why some in the field see them as better suited to off-the-shelf vaccines than individualised ones.
What could this cost?
The Moderna vaccine is a manufacturing problem as much as a biological one. Tissue from the patient's tumour is sequenced, the mutations unique to that tumour are identified and written into the product, and the whole process takes around six weeks. Then there is the bill.
"This will not be free," Sällberg says. "It could well run from 100,000 kronor to a million per patient."
It also asks a great deal of healthcare systems, and of regulators, who are in effect being asked to approve a production service rather than a single fixed drug. Sällberg thinks that problem has been solved once already. During the pandemic an updated COVID vaccine did not have to repeat the full approval process, because the regulator had already cleared the method. "The regulator approves the procedure for producing the vaccine," he says, "and the individual vaccines are then approved automatically."
Whether the wait matters at all depends on the patient. Following surgery and being tumour-free (the setting the melanoma trial studied), six weeks or more is tolerable. In refractory disease it is not: patients with advanced colorectal cancer routinely progress inside that window. That is the practical case for off-the-shelf vaccines, which could be given the moment a patient needs them.
The hard to treat tumours
Carl-Henrik Heldin has been asked when cancer will be cured for most of his forty years in this field. His answer has not changed.
"I don't believe there is any magic bullet," says the professor of molecular cell biology at Uppsala University. "We have to accept that this will happen gradually. There are certain cancers where the prognosis is still very poor and we do not have much to offer patients. I am thinking above all of brain tumours and pancreatic cancer."
Of those two, pancreatic cancer is the one getting worse: more common, globally, with no clear lifestyle explanation, and on the projections Heldin cites it will be the third, possibly second, most common cause of cancer death within twenty years. It is also the hardest case for everything above. A cold tumour, poor in mutations, shielded from the immune system, and fast enough that few patients can wait weeks for a drug to be built for them.
The field is going there anyway. "Several Phase 1 and 2 trials of vaccines against pancreatic cancer are under way," Sällberg says. "Some have cautiously promising data, and I am hopeful we will see progress within the next ten years. It is of course hard for someone who is ill today to wait for a drug that will arrive tomorrow."
Asked what the melanoma result means for patients, Malin Sund, professor of surgery at Umeå and Helsinki university hospitals and chair of the Swedish Cancer Society's research committee, sent the following statement:
"The development of cancer vaccines represents a highly promising field of research with the potential to transform oncological treatment. Although current data is encouraging, it is critical to note that these therapies remain in clinical development. Continued research and larger-scale trials are essential to determine patient benefit and optimise clinical application."
The reservation is not decorative. The detailed results are not published; they are due at a cancer conference this autumn. The trial's duration has not been disclosed, so nobody outside the two companies yet knows how long the protection lasts.
Sällberg does not think the wait will be long, though patients will need following for years. "I think it could start being used within one to a couple of years," he says. "This is not science fiction at all."
The melanoma trial finally answered whether a cancer vaccine can work. The harder question is whether one can be ready on the day a patient with a cold, fast-moving tumour needs it, without a biopsy, sequencing run or six-week wait.
For Heldin, gradual has never meant stalled. What he wants from the market is a shorter road from promising laboratory work to the clinic, before the patent term and the investors' patience are both used up.
"We will increase the chances that treatment works," he says, "and survival figures will get better and better. Even for these difficult tumour types."