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Shares of US vaccine maker Moderna skyrocketed more than 100%, nearly doubling the biotech's share price after it announced positive results from its first-ever late-stage trial of an experimental cancer vaccine.
With the surge, Moderna became the second-best performer in the S&P 500 so far in 2026, trailing only memory-chip maker Sandisk.
Breaking it down: the vaccine is being jointly developed with Merck and could be unprecedented in cancer treatment. It is designed as a custom-made vaccine for each patient, based on the specific genetic characteristics of their tumour.
And approval? Next year.
Why is this a big deal: initial data suggests the combination could become a new treatment option for melanoma, which accounts for only about 1% of skin cancers but causes the vast majority of skin cancer deaths.
Here's how it works.
Cancer can evade the immune system by switching off attacking T-cells. The mRNA vaccine gives the immune system the genetic fingerprint of a patient's tumour, training T-cells to recognise and attack the cancer.
The vaccine is being tested alongside Keytruda, Merck's blockbuster cancer immunotherapy. Keytruda works by taking the "brakes" off T-cells, allowing them to attack cancer cells more effectively.
The treatment is personalised to each patient. Researchers analyse the tumour after surgery, identify its specific mutations and use mRNA technology to create a vaccine that trains the immune system to recognise and attack those cancer cells.
This is the first time the technology has reached a Phase 3 trial, making it a significant milestone for personalised cancer treatment.
