Cancer Vaccines: Preventive Vaccines and Treatment Vaccines

What is it?

Two different applications are confused under the term cancer vaccine. Preventive vaccines create immunity against a virus that can lead to cancer and are given to people who have not yet had that infection. Treatment vaccines aim to provoke an immune response against the tumour in a person diagnosed with cancer.

Most vaccine news in the press concerns research products. Today there is no treatment vaccine used in every cancer that replaces routine chemotherapy or immunotherapy.

How does it work?

Preventive HPV vaccines generate antibodies against the types of human papillomavirus responsible for most cervical cancers. The hepatitis B vaccine protects against the virus that increases the risk of liver cancer.

On the treatment side, sipuleucel-T is used in some metastatic prostate cancers as a cellular product prepared against prostatic acid phosphatase. BCG, given into the bladder, stimulates local immunity in superficial bladder tumours with an attenuated bacterium. Talimogene laherparepvec is an oncolytic virus injected into the tumour in melanoma.

In which cancers is it used?

The HPV vaccine is not a treatment but a means of protection according to suitable age and programme; it does not treat the tumour once cervical cancer has developed. BCG can be part of intravesical treatment in selected bladder cancers that have not reached the muscle. The place of sipuleucel-T is narrow and it does not apply to every prostate cancer.

Which treatment is appropriate is discussed at the tumour board, with the relevant specialties taking part, by considering the type, stage and molecular features of the cancer and the person’s general condition together. A product in a clinical-trial vaccine comes into consideration only within the study and according to its eligibility criteria.

How is it given?

Preventive vaccines are given into the muscle on a set dose schedule. BCG is applied into the bladder by the urology team. Preparing sipuleucel-T requires collecting the patient’s own cells, and it is given in specialised centres. The oncolytic virus is injected into the lesion.

During chemotherapy or intense immune suppression, the timing of live or attenuated vaccines changes. Which vaccine is given when is written according to the treatment calendar.

During follow-up, blood tests, imaging and symptom review are read together. The dose or date may be changed according to side effects and organ function. The list of medicines used at home is updated at every visit. Sudden fever, shortness of breath, uncontrolled diarrhoea or bleeding should be reported the same day.

Possible side effects

With preventive vaccines, arm pain, mild fever and malaise are common, and serious allergy is rare. With intravesical BCG, frequent urination, burning and bleeding may occur; if the fever is high, infection is looked for. With cellular treatment products, chills, fever and changes in blood pressure may be seen.

The side-effect profile of research vaccines varies by product and is described separately in the consent form.