Salmonella-based Anticancer Vaccines and their Efficacy

Samad Farashi-Bonab* and Nemat Khansari

Salmonella-based Anticancer Vaccines and their Efficacy

Hundreds of years ago, variolation has been used to protect
humans against smallpox. At the end of the 18th century,
the cowpox virus was introduced by Edward Jenner as a safer alternative
to the variola virus, even though the virus was not identified
at that time.

During the 19th century after the discovery of bacteria
as causative agents of infectious diseases, attenuated or kilned
microorganisms or a component of the whole microorganism were
widely used to induce immunity against infectious diseases.

Use of these vaccines led to a dramatic decrease in death induced by
viral and bacterial agents. In recent decades, researchers attempted
to develop therapeutic vaccines against cancer with the aim of recruiting
lymphocytes and other immune cells to destroy cancerous
cells.

These vaccines were used as a monotherapy or in combination
with conventional therapeutic modalities such as surgery,
chemotherapy, and radiotherapy to prevent metastases and recurrence of cancer.

T-cells are an important part of protective adaptive immune responses.
Immunogenic cancer cell growth can result in
the generation of antitumor immune responses, especially T-cell responses.

Intravenous infusion of tumor-sensitized T-cells from
immune donors has resulted in regression of large established
tumors in T-cell-deficient recipients.

 

Induction of T-cell responses is the major aim of vaccines.
Vaccines can produce T-cell responses to a large number
of antigens. It is preferable to include more than one antigen in
vaccines to decrease the likelihood of immune escape.

Therefore, breaking immunological tolerance and immunosuppression
is necessary for therapeutic cancer
vaccines. Tumors employ numerous mechanisms limiting natural
or vaccine-induced antitumor immune responses.

Tumor cells and antigen-presenting cells
(APCs) expressing PD.

Vaccin Res Open J. 2019; 4(1): 5-11. doi: 10.17140/VROJ-4-111