A new clinical study of a virus known as GL-ONC1 was discussed by Dr. Valerie Rusch in a teleconference with the Meso Foundation on Monday, February 18th. Dr. Rusch is a mesothelioma surgeon at Memorial Sloan-Kettering Cancer Center in New York.
She has 25 years experience as a thoracic surgeon and has led many clinical studies in the treatment of mesothelioma.
The study, which began in January 2013, involves a one-time dose of GL-ONC1 although multiple doses may be considered in the future. There is even evidence of the drug already working. Although a regression in mesothelioma hasn’t been observed, doctors have seen stability in the participants’ disease. Many patients in the study haven’t required further treatment after administration of the drug.
Phase I Study of GL-ONC1
Currently the study is in phase I of clinical trials. As a phase I trial, the study is only enrolling a small number of patients with pleural mesothelioma. The purpose of the first phase is to test how well GL-ONC1 is tolerated in patients.
That is, doctors give increasingly larger doses of the drug to monitor any potential side effects and determine the most effective dose to administer in later phases.
“We’re actually fairly far along in the trial,” said Dr. Rusch. “We’re into the highest dose level now and we just finished treating our second patient at that highest dose level last week. And if all goes well, we’ll probably treat another six or seven patients at this dose level to ensure that it’s safe.”
GL-ONC1 has demonstrated very well-tolerated results among patients, showing signs of only minor side effects. The most common side effect, according to Dr. Rusch, is a slight fever that may last for a day or two at most. In response to how well the virus is working, Dr. Rusch said:
“We actually have some evidence that it’s working through patient follow up.”
This is the third trial that has been conducted of GL-ONC1 thus far. It has been tested in other cancers with similarly pleasing results around the world.
What is GL-ONC1?
GL-ONC1 is a type of intravenously administered viral therapy. The drug is a virus modified from a strain of a virus used to treat smallpox. Because GL-ONC1 is developed from a vaccine used throughout the world there is a lot known about the level of tolerance patients can handle.
“GL-ONC1 is a modified form of the smallpox virus, [the] vaccinia virus,” said Dr. Rusch. “So it’s a virus about which we know a great deal because it’s given to literally millions of individuals throughout the world. So we know actually that it’s a very, very safe virus to give.”
GL-ONC1 is a virus that binds to mesothelioma cells in the patient. When the virus incorporates into the cells, it starts reproducing and killing cancer cells. It has also been observed that GL-ONC1 travels to lymph nodes, preventing metastasis. It isn’t entirely understood how GL-ONC1 binds with and kills mesothelioma cells.
About two days after GL-ONC1 is administered, participants undergo a video-assisted thoracoscopic surgery to ensure the drug was delivered to the tumor. This is a minor procedure only requiring a few small incisions. During this thoracoscopic surgery, surgeons also perform a pleurodesis to reduce the buildup of fluid in the lungs if needed. Pleurodesis is a palliative surgery used to reduce pain and improve quality of life.
Benefit to Participants
Patients in any stage of pleural mesothelioma may be accepted into the study. Some of the basic criteria to enter the study include:
- The patient must have malignant pleural effusions.
- There must be space in the chest cavity to administer the drug.
- The patient must be off chemotherapy, radiation or immunotherapy treatment at least two weeks prior to enrollment in study.
Furthermore, because this is not a placebo-controlled study, all participants in the study receive treatment.
Ending the discussion, Dr. Rusch said: “it’s very clear that we need to seek novel therapies that hopefully have fewer side effects and ask patients to go through less in the way of length of treatment and side effects of treatment.”