This technology has
been patented after extensive testing in mice and the findings have been
published in the February issue of
, a constituent
journal of the American Chemical Society, Washington, USA.
The study was led
by Dr. Li Tang, PhD, who is an Assistant Professor and Head of the Laboratory
of Biomaterials for Immunoengineering at the EPFL School of Engineering, Lausanne,
Switzerland.
What are the Criteria for an Ideal
Therapeutic Cancer Vaccine?
An ideal
therapeutic cancer vaccine should satisfy the following two criteria:
- The vaccine should be able to precisely target the
cancer cell antigens as mutations in these cells are unique for each
individual
- A safe and effective vaccine delivery system should
be available for targeted delivery of the vaccine to the desired location
to generate a robust and specific immune response
How do Therapeutic Vaccines Differ from
Preventive Vaccines?
Preventive or
prophylactic vaccines confer protection prior to disease onset. Individuals are
immunized with these vaccines, which generate a powerful immune response,
producing large amounts of antibodies. The antibodies neutralize an invading
pathogen, thereby protecting the vaccinated individual from the disease.
On the other hand,
therapeutic vaccines are administered after disease onset. The purpose of these
vaccines is to help the body fight the disease, which in this case, is cancer. Moreover, these therapeutic cancer vaccines also reduce the
chances of relapse.
"There are various sorts of immunotherapies other than vaccines, but some
patients don't respond well to them. The vaccine could be combined with those
immunotherapies to obtain the best possible immune response," explains
Tang.
What are the Challenges in Delivering
Therapeutic Cancer Vaccines?
The major challenge
in delivering a therapeutic vaccine is targeting it to the desired location in
the body so that it can elicit a specific immune response.
In the case of therapeutic cancer vaccines, the specific immune response is
mediated via dendritic cells that present specific antigens to T-cells, so that
they get activated and attack the cancer cells. However, after injection of the
vaccine into an individual, it has to travel through the blood in order to
reach the lymph nodes, which are rich in immune cells.
In this process,
there is a high chance that the vaccine components could get dispersed and
diluted before reaching the lymph nodes, thereby reducing the vaccine's
efficacy to stimulate the immune system. This poses a huge challenge for
scientists who design and formulate the vaccines.
How were the Challenges Overcome?
The research team overcame the challenges by developing a new vaccine
formulation that reversibly binds together the individual components of the
vaccine. This
newly formulated vaccine, known as Polycondensate Neoepitope (PNE), consists of
neoantigens (mutated antigens specific to the cancer cells to be eliminated)
and an adjuvant for
boosting the immune response.
When the PNE is
mixed with a special solvent, its components bind together to form a large
entity that cannot be absorbed into the bloodstream, as a result of which it
directly travels to the lymph nodes, bypassing the blood circulatory system.
After reaching the lymph nodes, the PNE enters dendritic cells, where it
disassembles into its constituent components. This allows the dendritic cells
to present the specific antigen to the T-cells, which brings about a robust
cellular immune response that attacks the cancer cells.
Concluding
Remarks
"This new vaccine, combined with a highly advanced
analysis of each patient's neoantigens, should allow cancer patients' immune
systems to be activated in a personalized and safe way," says Tang.
The research team
is currently trying to elucidate the exact stage at which the cancer-specific
antigens are identified.
"This identification stage is just as vital," concludes Tang.
"Since these neoantigens aren't present in
healthy cells, accurate identification will allow us to target tumor cells very
precisely, without any toxicity to the healthy tissue."
Reference : - Redox-Responsive Polycondensate Neoepitope for Enhanced Personalized Cancer Vaccine - (https://pubs.acs.org/doi/10.1021/acscentsci.9b01174)
Source: Medindia
