Cancer vaccines, where do we stand?

What are the two types of cancer vaccines?

Preventive Vaccines

These vaccines aim to prevent cancer by targeting viruses known to cause it. For example, the HPV vaccine (FDA approved: Gardasil®, Gardasil-9® & Cervarix®) helps prevent cervical cancer, as well as other HPV-related cancers such as head and neck cancers. The hepatitis B vaccine (FDA approved: HEPLISAV-B®)reduces the risk of liver cancer caused by the hepatitis B virus. These vaccines have already made a global impact in reducing the burden of certain cancers.

Therapeutic Vaccines

Designed to treat existing cancers, these vaccines enhance the immune response against cancer cells. Mostly they can be categorized in the following types:

• Tumor Cell Vaccines: Utilize whole tumor cells, either from the patient or modified from other sources, to provoke an immune response.
• Antigen-Based Vaccines: Focus on specific proteins or peptides (antigens) found on cancer cells to stimulate the immune system.
• Neoantigen-Based Vaccines: Target patient-specific mutated proteins (neoantigens) that arise within cancer cells. These highly personalized vaccines are among the most promising approaches.
• Dendritic Cell Vaccines: Leverage dendritic cells, which play a critical role in the immune system, by loading them with cancer antigens before reintroducing them into the body to prime the immune response.

Despite significant progress, cancer vaccines still face challenges

Cancer vaccines still face challenges, and more especially therapeutic vaccines. Key issues include:

1. Tumor Heterogeneity: Cancers within the same patient can have various mutations, making it difficult to target all cancer cells with a single vaccine.
2. Immune Tolerance and Low Immunogenicity: Many cancer antigens resemble normal proteins, making it hard for the immune system to recognize them, especially in patients with a high disease burden.
3. Tumor Microenvironment (TME): Tumors create an immunosuppressive environment that diminishes vaccine effectiveness. Combination therapies, such as pairing vaccines with immune checkpoint inhibitors like PD-1/PD-L1 blockers, are needed to overcome this.
4. Personalization and Scalability: Neoantigen vaccines show promise but are costly and time-consuming to produce. Optimizing production and patient selection remains crucial to making them widely applicable.

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What are the current clinical developments in cancer vaccines?

Significant progress has been made in the clinical development of cancer vaccines. mRNA vaccines, such as Moderna’s mRNA-4157 targeting up to 34 neoantigens, have shown efficacy in solid tumors and are currently in phase II trials. BioNTech’s BNT122 is also under evaluation for colorectal cancer and other solid tumors. Additionally, dendritic cell-based vaccines like Sipuleucel-T (Provenge®), approved for treating prostate cancer, and oncolytic viral vaccines are under active investigation.

Cancer vaccines hold immense potential, especially as research continues to refine methods and address existing challenges. Combining vaccines with other immunotherapies, such as checkpoint inhibitors or CAR-T cells, may enhance their effectiveness. As we further improve on our knowledge around the immune system and cancer biology, cancer vaccines may be up to become more personalized and effective treatment options for patients in the future. We are glad to keep you posted. Don’t hesitate to contact our team!

About the author:

Volker, Great Explorer Oncology in Alcimed’s Healthcare team