A 49-year-old U.S. woman with advanced bone marrow cancer called multiple myeloma is effectively cancer-free after receiving an experimental trial that injected her a single dose of an engineered measles vaccine, according to a new U.S. study published this week.
The patient, with tumors all over her body, including a 3-cm- diameter one on her forehead, experienced complete remission of myeloma and has been clear of the disease for over six months, according to Mayo Clinic researchers who described their trial Wednesday in the journal Mayo Clinic Proceedings.
A second patient in the study, a 65-year-old woman, did not respond as well to the virus treatment that is selectively toxic to myeloma plasma cells.
However, high-tech imaging studies “provided a clear proof” that the intravenously administered virus specifically targeted the sites of tumor growth, they said.
The researchers said the trial is a “proof of concept” that virotherapy, destroying cancer with a virus that infects and kills cancer cells but spares normal tissues, can be effective against the deadly cancer multiple myeloma.
“This is the first study to establish the feasibility of systemic oncolytic virotherapy for disseminated cancer,” Mayo Clinic hematologist Stephen Russell, first author of the paper and co-developer of the therapy, said in a statement.
“These patients were not responsive to other therapies and had experienced several recurrences of their disease,” Russell said.
Virotherapy has a history dating back to the 1950s, according to the Mayo Clinic, and thousands of cancer patients have been treated with a host of various viruses.
“However, this study provides the first well-documented case of a patient with disseminated cancer having a complete remission at all disease sites after virus administration,” according to the Mayo Clinic statement. It was noted that both patients were studied at the highest possible dose of the therapy.
The normal dose of a measles vaccine contains 10,000 infectious units of the measles virus, Russell told local media. They, however, started out giving the two 1 million infectious units and gradually cranked up the dosage but it didn’t work until both patients were injected with 100 billion infectious units, enough to inoculate 10 million people.
Both women also had limited previous exposure to measles, and therefore fewer antibodies to the virus, and essentially had no remaining treatment options.
The researchers said their next step is to see if the measles vaccine works in a larger number of patients. They also want to test the effectiveness of the virotherapy in combination with radioactive therapy in a future study