How Do Cancer Treatment Vaccines Work?

Cancer treatment vaccines are a form of immunotherapy designed to help the body’s immune system recognize and fight cancer cells. Unlike preventive vaccines, which protect against viruses that can cause cancer (such as the HPV vaccine), cancer treatment vaccines target tumours in patients who already have cancer.

These vaccines work by training the immune system to detect specific proteins or antigens found on cancer cells. Once recognized, the immune system launches an attack against these cells, slowing the progression of the disease or even eliminating cancerous cells entirely.

Types of Cancer Treatment Vaccines

Different methods create cancer treatment vaccines based on how they interact with the immune system:

1. Tumour cell–based Vaccines are personalized vaccines created using a patient’s own tumour cells. By exposing the immune system to unique features of an individual’s cancer, these vaccines stimulate a highly targeted response.
2. Antigen-Based Vaccines – These vaccines use tumour-associated antigens commonly found on the cancer cells of multiple patientsAlthough still experimental, these vaccines aim to trigger an immune response in anyone whose cancer expresses the targeted antigen.
3. Dendritic cell vaccines use a patient’s own dendritic cells (a type of immune cell) to stimulate the immune system. The most well-known dendritic cell vaccine is sipuleucel-T, used to treat certain cases of advanced prostate cancer.

A related approach, oncolytic virus therapy, is sometimes classified as a cancer vaccine. This treatment uses modified viruses to infect and destroy cancer cells while selectively sparing healthy cells.

Talimogene laherparepvec (T-VEC, or Imlygic®) became the first FDA-approved oncolytic virus therapy. Derived from herpes simplex virus type 1, doctors inject it directly into tumours, where it replicates and causes cancer cells to burst and die. This process triggers a broader immune response against cancer cells throughout the body.

Cancers Treated with Cancer Vaccines

Currently, regulators have approved cancer treatment vaccines for:

• Prostate Cancer – Doctors use sipuleucel-T to treat patients whose cancer has spread, causes minimal symptoms, and no longer responds to hormone therapy.
• Melanoma – Physicians treat patients with T-VEC when their melanoma returns after surgery and cannot be removed with additional procedures.

Potential Side Effects

As with other immunotherapies, cancer treatment vaccines can cause side effects that vary from person to person. The most common include flu-like symptoms such as:

• Fever and chills
• Fatigue and muscle aches
• Nausea or vomiting
• Dizziness and headaches
• Trouble breathing
• Blood pressure changes

Some vaccines carry additional risks:

• Sipuleucel-T may increase the risk of stroke.
• T-VEC can trigger tumour lysis syndrome, where the rapid breakdown of tumour cells releases chemicals into the bloodstream that may harm the kidneys, heart, and liver.
• Since T-VEC contains herpesvirus, it may rarely cause herpesvirus infections, leading to blisters, eye irritation, nerve pain, or severe fatigue.

The Future of Cancer Treatment Vaccines

Cancer treatment vaccines represent a promising frontier in oncology, with ongoing research aimed at expanding their effectiveness to more cancer types. As technology advances, scientists are developing new vaccine formulations and combination therapies that enhance immune response, potentially making cancer treatment more personalized and effective.

Resources:
https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/cancer-treatment-vaccines