A new vaccine developed by Merck and Moderna has demonstrated the ability to prevent cancer recurrence in melanoma patients when combined with existing immunotherapy treatment, marking a significant development in personalised cancer care.

Pharmaceutical companies Merck and Moderna have announced positive interim results from a clinical trial of a personalised vaccine designed to prevent melanoma recurrence in high-risk patients. The vaccine, called Intismeran, was administered following surgery to patients with advanced skin cancer, alongside the immunotherapy drug Keytruda. According to the companies, the combination treatment significantly extended the period during which patients remained cancer-free compared to Keytruda alone, while reducing the risk of cancer spreading to other organs.

The trial involved more than 1,000 patients with stage two, three, or four melanoma. The vaccine works by utilising mRNA technology—similar to some Covid-19 vaccines—to target mutations specific to each patient's tumour. Scientists extract a tissue sample from the patient's cancer, sequence its DNA, and create a customised vaccine that trains the immune system to identify and attack remaining cancer cells.

While cancer researchers have welcomed the findings as encouraging, they emphasise caution regarding the announcement. Dr Talisia Quallo of Cancer Research UK noted the research "shows promise" but stressed that the interim data requires full independent review. Dr Lennard Lee from the University of Oxford described it as "good news for patients with melanoma" while highlighting broader implications for personalised cancer treatment development. The full trial results have not yet been published or subjected to peer review by independent experts.

Before becoming available to patients, the treatment must still complete the regulatory approval process. Merck and Moderna are also investigating similar personalised vaccines for lung, bladder, and kidney cancers. Stock prices for both companies have risen significantly following the announcement.