A New Phase for Personalised Cancer Vaccines

Moderna and Merck’s positive Phase 3 melanoma results mark an important milestone for personalised cancer vaccines, strengthening the evidence that tumour sequencing, computational neoantigen selection and mRNA technology can be combined to create patient-specific treatments. However, detailed clinical results are still awaited, and important questions remain, including around the durability of the clinical benefit, its applicability across other cancers and the ability to manufacture these therapies reliably at scale.

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A Phase 3 Milestone

On 19 August 2026, Moderna and Merck announced positive topline results from a Phase 3 trial of intismeran¹, their personalised mRNA cancer vaccine, in patients with high-risk melanoma following surgery. The treatment, given in combination with Keytruda, improved both recurrence-free survival and distant-metastasis-free survival compared with Keytruda alone.

The announcement provided the strongest evidence yet that a personalised cancer vaccine can improve patient outcomes in a large late-stage trial. According to Moderna and Merck, it was the first positive randomised Phase 3 readout for an individualised neoantigen therapy. The trial enrolled 1,137 patients, although detailed results, including the size and durability of the benefit, have not yet been published.

At the Morgan Stanley Global Healthcare Conference on 14 September², Moderna emphasised that melanoma is only the first major test of the approach. Intismeran is being evaluated in nine trials across several tumour types and stages of disease, but whether the results can be replicated beyond melanoma remains an important question.

How Intismeran Is Made and Designed to Work

Unlike standardised cancer treatments, personalised neoantigen vaccines are tailored to the individual patient’s tumour. The process begins with a sample of the surgically removed tumour. Its genetic information is analysed to identify mutations that may produce unique targets, known as neoantigens, on the cancer cells. Moderna then manufactures a personalised mRNA therapy encoding up to 34 selected neoantigens. It is given in combination with Keytruda, an immunotherapy that helps the immune system attack cancer cells. The combination is designed to train the immune system to recognise and destroy residual cancer cells displaying those neoantigens.

From Tumour Analysis To Treatment

Diagram 1. Simplified illustration of how intismeran is developed and designed to work. Source: VanEck.

The Potential Market Opportunity

The commercial opportunity for personalised cancer vaccines is potentially significant, but it remains highly dependent on successful clinical translation. Grand View Research⁴ estimates that the global market could grow from $226.7 million in 2025 to $1.45 billion by 2030, projecting a compound annual growth rate of 44.9%. This forecast reflects expectations that newer approaches, particularly personalised neoantigen vaccines delivered through mRNA platforms, will move beyond clinical development and complement the existing vaccine segment. However, it should be treated as a market forecast rather than an established growth trajectory. Forward-looking statements, including market-size projections, are estimates based on assumptions that may not materialize. They are not guarantees or a reliable indicator of future results.

Source: Grand View Research. Personalized Cancer Vaccine Market Size Report 2025 to 2030. Market size. Investing is subject to risk, including the possible loss of principal.

Several technologies are helping make this transition possible. Next-generation sequencing can identify mutations unique to a patient’s tumour, while AI and machine-learning tools can help predict which resulting neoantigens are most likely to generate an immune response. Advances in mRNA platforms then allow multiple selected neoantigens to be incorporated into a single personalised therapy.

The broader clinical need is substantial. According to the WHO’s 2026 global cancer report, 20.6 million people were diagnosed with cancer worldwide in 2024, and annual diagnoses are projected to reach 35 million by 2050⁵. However, personalised cancer vaccines are unlikely to be suitable for every patient or replace surgery, chemotherapy, radiotherapy or existing immunotherapies. Their initial opportunity may instead lie in selected cancers and treatment settings, particularly after surgery, when the objective is to eliminate residual disease and reduce the risk of recurrence or metastasis.

The Wider Ecosystem

The market reaction to the Phase 3 announcement extended beyond Moderna, with shares across the sequencing and cancer-vaccine industries rising in the days that followed. Although short-term market movements can reflect many factors, the broader response suggests that investors viewed the results as potential validation of the wider personalised oncology ecosystem.

This reflects the range of technologies required to create and deliver these treatments. Personalised cancer vaccines depend on tumour sequencing to identify mutations, computational tools to select promising targets, specialised manufacturing to produce each patient’s therapy, and diagnostics and immunotherapies to support treatment. Wider adoption could therefore create opportunities across several parts of the healthcare value chain.

The approach is also designed to complement existing cancer treatments rather than replace them. In the Phase 3 trial, the personalised vaccine helped direct the immune system towards tumour-specific targets, while a checkpoint inhibitor helped sustain the immune response. If this combination proves effective in other cancers, the opportunity could extend across vaccine platforms, immunotherapies and the supporting infrastructure.

What to Watch Next

The Phase 3 announcement is an important milestone, but key uncertainties remain. Detailed results have not yet been published, including the magnitude and durability of the clinical benefit, while overall survival is still under evaluation. It also remains unclear whether success in melanoma will translate to other cancers.

Manufacturing and regulation present additional challenges because every treatment must be individually designed, produced and tested. Wider adoption will depend on whether these therapies can be manufactured reliably at scale and whether regulators can establish workable standards for patient-specific products.

Taken together, these clinical, manufacturing and regulatory questions will determine how far personalised cancer vaccines can progress beyond this initial success and whether the results mark a breakthrough for one treatment or the beginning of a broader shift in cancer care.