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Clinical trials are important for testing the effectiveness and the safety of experimental drugs and therapies. They also provide additional options for patients with advanced cancer, like late-stage mesothelioma. For some it may be a last chance to try to manage this terrible disease.
Several trials are currently testing a new immunotherapy drug called anetumab ravtansine, which is made by Bayer. There have been some setbacks, but there is still great promise for this new therapy, which selectively targets certain types of cancer cells to deliver a cytotoxic drug directly to them.
Anetumab Ravtansine and ADCs
Anetumab ravtansine is an experimental immunotherapy drug made by German pharmaceutical company Bayer and biotech companies ImmunoGen and MorphoSys. As an immunotherapy drug, the purpose is to harness and use a cancer patient’s immune system to target and kill cancer cells. Immunotherapy drugs can do this in many different ways, and anetumab ravtansine is an example of a type called antibody-drug conjugates, or ADC.
An ADC is a drug that combines an antibody with a cytotoxic drug. An antibody is a protein that recognizes chemical signals on pathogens, signaling the immune system to target them. Antibodies have been developed by researchers to target and lead immune cells to cancer cells. A cytotoxic drug is a chemical that actually kills the cancer cell. Chemotherapy drugs, for instance, are cytotoxic.
How Anetumab Ravtansine Works
ADCs work by using the antibody to find and recognize cancer cells and deliver the cytotoxic drug to them. In chemotherapy patients are given systemic, non-specific cytotoxic drugs. This means they circulate the body and kill any fast growing cells, both cancer and healthy cells. The delivery system of ADCs like anetumab ravtansine ensures that the drug only goes to and acts on cancer cells.
The drug is made up of three parts: the antibody, the cytotoxic drug, and a linker molecule that holds them together. When given to the patient the antibody recognizes and attaches to a specific protein, known as an antigen, on the surface of cancer cells. The cancer cell absorbs the entire three-part drug. In the cell the linker dissolves and the cytotoxic drug is free to take action and kill the cell. The targeted nature of ADCs means that, if effective, they will produce fewer side effects than traditional therapy.
Anetumab Ravtansine and Mesothelioma
For an ADC to work it must have an antibody that targets an antigen on the surface of cancer cells. Researchers created anetumab ravtansine to target an antigen known as mesothelin. Mesothelin is prevalent on the surface of mesothelioma cancer cells but also on the cells that make up pancreatic and ovarian tumors. Healthy cells may have some mesothelin, but not nearly as much as these cancer cells, so they are not targeted to any significant degree by the drug.
Once anetumab ravtansine is absorbed into a mesothelioma, pancreatic, or ovarian cancer cell the cytotoxic drug disrupts a specific process. That process in the cell is necessary for it to grow, develop, and divide. The drug stops cells from dividing, and they simply die.
Clinical Trials with Anetumab Ravtansine
Anetumab ravtansine is a drug giving a lot of hope to patients with mesothelioma. It is still in clinical trials, though, and is not yet an approved treatment. There are currently six trials associated with the National Institutes of Health and the National Cancer Institute using this drug with patients with mesothelioma and other cancers that overexpress mesothelin.
One study that is currently active is testing the safety and potential side effects of anetumab ravtansine both with and without another immunotherapy drug called pembrolizumab (Keytruda). Patients involved in this phase I and II trial have pleural mesothelioma and have already undergone chemotherapy.
Another clinical trial has been ongoing since 2015 and involves patients with advanced pleural mesothelioma or non-small lung cell cancer. Still in phase I, this study is looking at the safety and effectiveness of combining anetumab ravtansine with the standard chemotherapy drugs pemetrexed and cisplatin.
A Disappointing Failure
One early trial of anetumab ravtansine conducted by Bayer has already failed to meet its target with mesothelioma patients. Participants were either given the trial drug, anetumab ravtansine, or a the chemotherapy drug vinorelbine. The study results have so far been disappointing with no evidence that the drug slowed the progression of cancer in the participants.
While the results have been disappointing for this trial, researchers have not given up on anetumab ravtansine. The trials that are ongoing or about to start will continue, and there is hope that the results of these trials, including combinations of drugs will be better. It is a setback but not the end of anetumab ravtansine.
If you are interested in clinical trials or think you may qualify for a trial with anetumab ravtansine, talk to your oncologist or other members of your medical team. There are requirements you must meet, and it is also important to consider the risks of joining clinical trials. Immunotherapy drugs like anetumab ravtansine are showing great promise as a new line of treatment for difficult cancers and patients can help make them better by participating.
Page Edited by Patient Advocate Dave Foster
Dave has been a mesothelioma Patient Advocate for over 10 years. He consistently attends all major national and international mesothelioma meetings. In doing so, he is able to stay on top of the latest treatments, clinical trials, and research results. He also personally meets with mesothelioma patients and their families and connects them with the best medical specialists and legal representatives available.