VISTA protein clinical trials recently tested a drug known as CA-170 for its potential effectiveness as a type of cancer therapy. CA-170 is an immunotherapy drug that prevents the deactivation of immune system T-cells by the cancer cells. VISTA clinical trials included mesothelioma patients and recently concluded.
What Is VISTA? Immune Checkpoint Proteins and Inhibitors
VISTA (V-domain Ig suppressor of T-cell activation) is a type of protein that helps cancer cells avoid attack by the body’s immune system.
What Are Immune Checkpoints?
Immune system T-cells have proteins on their surfaces known as checkpoints. Other cells have proteins on their surfaces that interact with these checkpoints, turning them off and telling the immune cell not to attack. The VISTA clinical trial was the first to test a drug that targets this specific protein.
What Are Immune Checkpoint Inhibitors?
Healthy cells have specific proteins that bind to and disable checkpoints on T-cells. This protects them from the immune system.
Unfortunately, cancer cells also often have these proteins they evolved to protect them from the immune system. PD-1 is one example of a checkpoint protein targeted by new cancer therapies. T-cells have PD-1 on their outer surfaces. When PD-1 binds to a protein known as PD-L1 on other cells, it knows not to attack that cell.
Drugs that target either PD-1 or PD-L1 can potentially block the interaction between immune cells and cancer cells. This allows T-cells to recognize, attack, and kill cells in the tumor.
How Is VISTA Important for Mesothelioma?
Immunotherapy effectiveness often depends not just on the type of cancer but also on the individual. Most pleural mesothelioma patients do not respond to therapies involving PD-1 or PD-L1.
Another protein, known as VISTA, is similar to PD-L1, making it a more promising target for immunotherapy.
VISTA is expressed by more than 90% of mesothelioma cancer cells, making it an excellent target for new therapies. If a drug can block VISTA, the immune system has a better chance of targeting the cancer cells
What Is CA-170?
The new drug recently tested in clinical trials is known as CA-170. Curis, Inc, a biotechnology company that focuses on cancer treatments, is developing and testing the drug. CA-170 is an immune checkpoint inhibitor that targets VISTA.
CA-170 is new and unique in that it is the first therapy tested to target VISTA. Other checkpoint inhibitors that target PD-L1 have already been discovered and tested. Drugs like atezolizumab (Tecentriq) and durvalumab (Imfinzi) are proving to help the immune system to identify and fight cancer.
But CA-170 is the first new therapy that hypothesizes that it can target both PD-L1 and VISTA. The early stages of testing show promising results that this drug can help patients with non-small cell lung cancer. Everyone is interested to see how it works in mesothelioma.
VISTA Clinical Trials
The CA-170, VISTA, and PD-L1 phase I clinical trial is now complete. The trial was conducted in several locations, including San Francisco, California, and Denver, Colorado. Even though this trial is no longer accepting participants, others will continue to open as the compound begins to show safety and efficacy.
Patients with mesothelioma began treatment with the drug in January 2019. The purposes of the phase I trial are to determine the drug’s clinical effects, how it works, and if it is safe. Mesothelioma patients were given two levels of doses administered every day for two twenty-one-day cycles.
How Can Mesothelioma Patients Get Involved in Clinical Trials?
Clinical trials not only test for effectiveness but also test the safety of new therapies. When deciding to participate in any clinical trial, it is important to weigh the risk of side effects. It is also essential for patients to understand that the outcome of these therapies may not be what they hope.
CA-170 is such a new drug that there are no currently known common side effects. Animal and laboratory studies cleared it as safe enough for human clinical trials; however, this does not mean this drug will be proven safe for human patients.
One clinical trial targeting VISTA is currently recruiting mesothelioma patients. Phase 1 Study of CI-8993 Anti-VISTA Antibody in Patients With Advanced Solid Tumor Malignancies will provide participants with a compound designed to target VISTA in order to evaluate the safety of the treatment.
Clinical trials often have stringent inclusionary criteria to make sure suitable patients get a chance to participate. While every trial is different, examples of these criteria for inclusion in a study are:
- Be 18 years old or older
- Have been given a life expectancy of three months or longer
- Have adequate organ functioning and bone marrow
- Be able to swallow oral medications
- Have negative pregnancy test results
- Have a measurable disease
- Be diagnosed with a cancer that has high VISTA expression, like mesothelioma, or have a cancer not responding to standard therapy
If you are interested in learning more about any upcoming clinical trials, talk to your oncologist or other members of your medical team. Mesothelioma patients often qualify for trials because of the aggressive nature of this cancer and how difficult it is to treat.Get Your FREE Mesothelioma Packet
Page Written by Mary Ellen Ellis
Mary Ellen Ellis has been the head writer for Mesothelioma.net since 2016. With hundreds of mesothelioma and asbestos articles to her credit, she is one of the most experienced writers on these topics. Her degrees and background in science and education help her explain complicated medical topics for a wider audience. Mary Ellen takes pride in providing her readers with the critical information they need following a diagnosis of an asbestos-related illness.
Page Medically Reviewed and Edited by Kyle J. Becker, PharmD, MBA, BCOP
Kyle J. Becker, PharmD is certified by the Board of Pharmacy Specialties in Oncology Pharmacy. Dr. Becker earned his pharmacy degree from Shenandoah University and he currently serves as an oncology pharmacist at Parkview Cancer Institute.