Therapeutic vaccines represent a new way of fighting tumors by stimulating a patient’s immune system to attack cancer cells. The U.S. Food and Drug Administration (FDA) has currently approved two of these types of vaccines: sipuleucel-T for metastatic prostate cancer and talimogene laherparepvec for metastatic melanoma. However, many other cancer vaccines are being investigated in clinical trials.

A new class of vaccines, different than the currently approved ones, uses modified vaccinia viruses to deliver the immune-stimulating agents. Although this type of vaccine is not yet FDA approved, it is being studied in clinical trials at hundreds of sites internationally and the first vaccinia therapies are expected to be approved in the near future. Any oncology nurse may encounter a patient who has received such a vaccine as part of a clinical trial or later in the year during regular treatment once the vaccinia have been approved and therefore need to understand how to recognize and minimize potential hazards for providers as well as patients.

In her article in the December 2016 issue of the Clinical Journal of Oncology Nursing, McMahon provided an overview of safety recommendations, staff education, and patient education surrounding clinical trials with viral vector vaccines such as vaccinia virus.

The Science Behind Viral Vector Vaccines

According to McMahon, this class of vaccines uses attenuated live viruses to deliver tumor-specific antigens that will spark a patient’s immune system to recognize malignant cells as foreign. Pox virus vectors, such as vaccinia virus, have been used in smallpox vaccines for more than 100 years. This type of vector is ideal for vaccines “because they can infect human cells but cannot incorporate themselves in to human DNA. They can contain a large amount of foreign DNA, can efficiently infect antigen-presenting cells, and are highly immunogenic,” McMahon explained.

Two of the prominent vaccines currently under study that use vectors are PROSTVAC-V TRICOM and PROSTVAC-F TRICOM, both of which are being investigated for prostate cancer. They are involved in multiple clinical trials, including a global randomized, controlled phase III trial. Both vaccines use genetically altered poxvirus and are administered subcutaneously, typically in the upper thigh area.

Notably, the vaccinia vaccine is only used as the priming dose in the first treatment; subsequent doses are boosters that are manufactured differently and do not replicate in humans, so they do not carry the same safety requirements.

Education Keeps Staff Safe

Vaccinia is classified as a biosafety level 2 hazard, an infectious biologic substance, McMahon said. Safety recommendations for working with the agent are similar to those for other biohazardous agents such as chemotherapy.

  • Use standard personal protective equipment (e.g., gloves, gowns, goggles, masks).
  • Place the patient in a private room and use contact isolation during administration.
  • Ensure good handwashing using soap and water.
  • Properly handle and dispose personal protective equipment and syringes.

Additionally, staff members who are pregnant or trying to conceive, immunocompromised, or have chronic skin disorders such as atopic dermatitis, should not administer the vaccine.

Staff members who administer the vaccine are recommended to have received the smallpox vaccine, but not required, McMahon noted. Smallpox is caused by variola virus, not vaccinia, but a theoretical risk for infection exists. Laboratory workers are at greater risk than physicians and nurses whose only contact is with contaminated materials (e.g., dressings) and who adhere to infection control measures. Additionally, the subcutaneous administration method (as opposed to scarification) further reduces the risk of contact transmission.

Patients need to receive instruction on home care of the vaccination site, safe handling of contaminated materials, and restrictions on contact with others.

To put the risk into perspective, McMahon explained that of the more than 1,000 patients who have received vaccinia vectors, no cases of contact vaccinia have been reported by patients, study personnel, or others.

What to Teach Patients

Patients need to receive instruction on home care of the vaccination site, safe handling of contaminated materials, and restrictions on contact with others. See Figure 1 for a complete list of patient teaching points.

With proper education and knowledge, oncology nurses will be prepared to safely administer live-virus vaccines and care for patients receiving them when they are approved in the near future. For more information on vaccinia vaccines, refer to the full article by McMahon.

This monthly feature offers readers a concise recap of full-length articles published in the Clinical Journal of Oncology Nursing (CJON) or Oncology Nursing Forum. This edition summarizes “Minimizing Hazards Associated With Live-Virus Immunotherapeutic Cancer Vaccines,” by Sheri McMahon, RN, BSN, which was published in the December 2016 issue of CJON. Questions regarding the information presented in this article should be directed to the CJON editor at Photocopying of this article for educational purposes and group discussion is permitted.

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