Rabbit Virus Eliminates Multiple Myeloma Cells

Myxoma, a rabbit virus, was found to eliminate human multiple myeloma cells, which could result in an effective therapy.

Highlights:

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.

Multiple Myeloma

Multiple myeloma 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.

Multiple Myeloma / Plasma Cell Myeloma–Symptoms-Treatment-Prognosis-Support Group
Multiple Myeloma caught public attention when model turned actress Lisa Ray, who worked in Deepa Mehta’s ‘Water’ , declared that she had the incurable Multiple Myeloma.

‘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.

Viral Oncolytics

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.

Multiple Myeloma Patients Benefit from Treatment at More Experienced Centers
People diagnosed with multiple myeloma are more likely to live longer if they are treated at a medical center that sees many patients with this blood cancer.

Stem Cell Transplant

Stem cells 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.

Systemic Treatment 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 of relapse.

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.

Multiple Meloma Linked to Defective Protein Factory
Defects in the ribosome of multiple myeloma patients have been discovered by researchers.

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 barriers are

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.

A Promising Oral Drug Combo for Multiple Myeloma Treatment
In patients with newly diagnosed multiple myeloma, the investigational drug ixazomib when taken orally in combination with lenalidomide and dexamethasone is promising.

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.

The 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.

References:

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

Source-Medindia