It worked in the dish, and it worked on the lab mice, leading to the latest Phase I clinical trial at the Mayo Clinic to see if a genetically-altered measles virus can work as a reliable therapy for patients with pleural mesothelioma.
There is promise.
For generations, the measles virus in America was a real problem, ranging from serious complications to mild inconveniences before an infant vaccine eliminated much of the concern.
Today, the measles virus has shown the potential to do some serious good.
The Mayo Clinic in Rochester, Minnesota, in collaboration with the National Cancer Institute (NCI), is testing the virus for the first time in humans with mesothelioma, looking to establish the optimal dosage levels without causing any serious side effects.
Pulmonary Specialist Tobias Peikert, M.D., detailed the dose-escalation trial Tuesday night during a teleconference with the Mesothelioma Applied Research Foundation (MARF).
Investigators hope the virus can kill tumor cells without harming good cells, along with triggering an anti-tumor response.
"It kills mesothelioma cells in the dish. It has killed mesothelioma tumors set up in animal models very effectively," said Peikert said. "And in addition to the direct effect on tumor cells, it may stimulate an immune response. The hope is that there are two beneficial effects."
6-Month Mesothelioma Trial Nearly Complete
In the Mayo Clinic lab, mice presented with mesothelioma tumors lived twice as long after just a single injection of the measles virus. Researchers there reported that some of the mice appeared to be cured after the injection.
The first two patients in Minnesota are just finishing the six-month trial, having received six cycles of the MV-NIS treatment at 28-day intervals. Peikert reported no complication with dosage, but he did not talk about the effect on the cancer within the individuals.
The Mayo Clinic already has researched, and been encouraged by, the measles virus with ovarian and prostate cancers trials, giving it a baseline dosage level from which to start with mesothelioma. If the third participant also shows no side serious side effect from MV-NIS, the dosage levels will increase for the next three patients who participate.
Peikert said he expects the trial to last another 2 to 2 ½ years as they slowly increase dosage levels.
Measles Virus Can Be Engineered
Researchers first became interested in exploring the measles virus for medical purposes years ago, but almost by accident. Oncologists noticed that cancer patients who accidentally contracted natural measles underwent spontaneous tumor regressions, but could not explain why.
Researchers then discovered that the measles offered a platform to build safe oncolytic viruses that could be effective by attacking tumor cells without harming healthy cells. The virus can be engineered to increase tumor specificity and potency.
One of the difficulties, though, is the prevalence of the body's own anti-measles immunity, which impedes the spread and delivery of the virus, making the dosage level so important.
The vaccine is administered directly into the pleural cavity through a catheter. The virus can be administered as a first, second or third line therapy for mesothelioma patients. To qualify for the trial, a patient's mesothelioma must be confined to a single pleural cavity.
"We have to get the virus into close proximity with the tumor to allow us to infect the cells more effectively," Peikert said.
The virus includes a type of radioactive iodine, making it possible to get non-invasive imaging studies that can follow it in the patients. The new gene in the virus makes it a toxic drug capable of killing cancer cells.
"We've taken a new viral agent, repositioned it for this disease and are advancing it as an entirely novel treatment," explained Stephen Russell, M.D., molecular researcher at the Mayo Clinic.
Peikert expects to recruit up to 36 patients for the study. Anyone interested can contact the Mayo Clinic Trials referral office. More information is available at ClinicalTrials.gov.
The trial, which hopes to expand to the Mayo facility in Minneapolis, requires considerable time and travel. Participants, in the first cycle, must stay in the Rochester area for monitoring at least for two weeks.
The time commitment is less for subsequent cycles of the therapy.
