- Scientists have
found that a rabbit virus, myxoma, can act on human multiple myeloma cells
and eliminate them.
- 25% of mice were
rid of multiple myeloma on treatment with myxoma.
- 65% of mice
showed reduction in cancer after treatment with myxoma.
The introduction of the
myxoma virus (MYXV) onto multiple myeloma (MM) cells by a research team from
Medical University of South Carolina (MUSC) showed that there was an elimination
of most of the malignant cells. The study published in the
Molecular Therapy - Oncolytics
described how the
introduction of MYXV led to a strong reaction from the immune system that
completely removed the disease in animals.
is a type of blood
cancer, which is found to develop in the plasma cells present in the bone
marrow. The plasma cells are responsible for the development of antibodies that
are vital for the maintenance of a healthy immune system.
‘The use of myxoma virus in therapy for multiple myeloma would aid in eliminating cancer without infecting the host.’
The affected plasma
cells are termed myeloma cells and they lead to the production of abnormal
antibodies called M proteins. These M proteins are the hallmark
characteristic associated with multiple myeloma
. The myeloma cells are all
identical to each other and they result in symptoms such as bone damage or
kidney proteins. This is one of the most difficult to treat cancers, even all
the new regimens of chemotherapy. Most patients are found to succumb to the
disease when they become resistant to the chemotherapy treatment or due to
reinfusion of cancer cells during stem cell transplant.
In the quest to identify
a new approach that would provide an effective treatment for multiple myeloma,
Dr. Eric C. Bartee, who is an assistant professor of Microbiology and
Immunology at MUSC, along with his colleagues used viral oncolytics to solely
target and destroy the target cancer cells. The highlight of the study has been
that the use of these oncolytics resulted in the destruction of the cancer
cells but with no sign of relapse.
The current study has
been the result of several years of study by Dr. Bartee who has been using the
myxoma virus to destroy multiple myeloma cells in culture. This virus, in
nature, affects only rabbits and is not infectious to humans. However, when
this virus was added to the multiple myeloma cancer cell lines, it was found to
kill human multiple myeloma cell lines.
Stem Cell Transplant
of the patient are often used to treat multiple myeloma
patients but they have a high chance of relapsing into cancer due to the
presence of cancer cells in the stem cells. Studies have shown that treating these
stem cells with the myxoma virus aided in eliminating multiple myeloma cells, a
technique that was carried out prior to administration to the patients. This
would, therefore, prevent relapse.
with Myxoma Virus
The scientists wondered if the successful
removal of the multiple myeloma cells from the stem cells would ensure
destruction of the cancer cells beyond the concept of transplantation. When the
MYXV was introduced as a systemic treatment, it resulted in
- 66% of mice showed decrease in disease progression.
- 25% of mice showed complete elimination of disease with no sign
Host Immune System
The MYXV is a rabbit
virus and is not found to replicate in the human multiple myeloma (MM) cells,
the elimination of cancer could be due to the immune system of the host. The
bone marrow was unaffected by the introduction of the virus.
This showed that
- The immune system of the host remained functional
- It could fight against the cancer
- Administration of MYXV increased CD8+ cells
The initial studies conducted by the research team have shown
promise but there are still many steps that need to be traversed before this
model of treatment is made available for the clinical setup. Two significant
- The large scale production of this virus
- Demonstrating a high response rate in human studies
Since cancer elimination
is mediated by the immune system and not by the virus itself, the virus could
be included in immune modulatory treatment procedures which would aid in
increasing the anti-tumor response.
Resistance to Therapy
Patients who undergo
many cycles of chemotherapy may develop resistance but it is very difficult for
multiple myeloma patients to develop resistance to the virus.
Dr. Bartee further added
that this form of therapy increased the chances of survival which could prove
to be useful in the therapy for multiple myeloma.
non-traditional method of therapy needs to undergo extensive testing and trials
before it enters mainstream therapy, but the hope of an effective treatment
method is significant.
- What is Multiple Myeloma? - (https://www.themmrf.org/multiple-myeloma/what-is-multiple-myeloma/)
- Eric Bartee, Mee Y Bartee, Bjarne Bogen, Xue-Zhong Yu. Systemic therapy with oncolytic myxoma virus cures established residual multiple myeloma in mice. Molecular Therapy Oncolytics, 2016; 3: 16032 DOI: 10.1038/mto.2016.32