Breaking barriers: Advances and challenges in therapeutic cancer vaccines

2024-04-01

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Imagine a world where we can arm the body's defenses, pre-emptively training the immune system to unleash a formidable army of tumor-fighting cells. While preventive vaccines have triumphed against specific cancer types, the journey to unlock the true potential of therapeutic vaccines has been a formidable challenge.

Yet, in the face of setbacks, the therapeutic horizon for cancer vaccines is experiencing a renaissance. Fueled by cutting-edge technologies and a deeper grasp of tumor-associated antigens, these vaccines offer a beacon of hope in the ongoing battle against cancer worldwide.

Vaccines in development or on the market today

In recent years, there are a few examples of cancer vaccines in development or already approved worth noting:

HPV Vaccines have been developed to prevent infection with certain strains of the human papillomavirus (HPV), which is a major cause of cervical cancer.

Bladder cancer vaccine is a type of immunotherapy used to treat bladder cancer. It is a live attenuated strain of Mycobacterium bovis that stimulates the immune system to attack cancer cells.

Melanoma Vaccine is a modified herpes simplex virus type 1 that has been approved for the treatment of advanced melanoma. It works by causing the immune system to attack cancer cells.

Lung cancer vaccines, while not traditional vaccines, use immune checkpoint inhibitors to treat certain types of lung cancer by blocking proteins that prevent immune cells from attacking cancer cells.

In other positive advancements in the knowledge of cancer treatments, administering specific chemotherapy in low doses, a technique known as metronomic chemotherapy, has proven effective in eliminating immunosuppressive cells within the tumor microenvironment. When paired with therapeutic vaccines, these dual treatment strategies synergize to expose the presence of a tumor to the immune system, prompting a more rapid and targeted response.

The significance of combination therapies becomes evident in clinical trials aimed at improving patient survival rates. Research demonstrates that patients experience enhanced survival when treated not only with cancer vaccines but also in conjunction with agents such as cyclophosphamide. This particular chemotherapy variant depletes regulatory T cells in the tumor microenvironment, fostering increased infiltration of T cells, and amplifying the overall immune response to the tumor.

Utilizing low-dose metronomic chemotherapy or incorporating checkpoint inhibitors in a tandem or combined therapeutic approach proves instrumental in augmenting the comprehensive immune response to the tumor. With gut microbiome’

Challenges to overcome

While cancer vaccines are promising immune-therapeutics for establishing immune surveillance, it is important to note that further research has to be conducted by identifying neoantigens, developing combination therapies and optimizing the current vaccine platforms before cancer vaccines become a potent strategy in immunotherapy.

Some key challenges, which may impact a vaccine’s effectiveness and successful integration into mainstream cancer treatment, include:

Tumor Heterogeneity: Since cancers can differ significantly between individuals and even within the same tumor, this complexity makes it challenging to identify universal antigens or targets suitable for a broad range of patients.

Immune Suppression: Tumors often create a suppressive microenvironment that hinders the immune system's ability to recognize and attack cancer cells.

Limited Immunogenicity: Some tumor antigens may not be inherently immunogenic, meaning they may not stimulate a robust immune response.

Identification of Suitable Antigens: Finding antigens specific to cancer cells while sparing healthy cells is a delicate task. Identifying antigens that trigger a strong immune response against cancer while avoiding autoimmune reactions is crucial.

Delivery Challenges: Ensuring effective and targeted delivery of the vaccine to the tumor site can be difficult. Factors such as poor vascularization, tumor barriers and potential immune clearance can hinder the successful transport of therapeutic agents to the intended destination.

Optimal Timing and Combination Therapies: Determining the best timing for administering cancer vaccines and identifying effective combinations with other treatments, such as chemotherapy or immunotherapies, presents challenges in clinical trial design and patient management.

An optimistic future for cancer vaccines

The progress in therapeutic cancer vaccines exemplifies the transformative power of unexpected industry innovations. Sustaining this momentum holds the promise of making therapeutic vaccines a reality for global cancer patients. The increasing approval of such vaccines stands to revolutionize cancer treatment, particularly for inoperable cases with low survival rates. This perseverance signals a positive trajectory, bringing us closer to the ultimate goal of eradicating cancer.