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What is PTC299? |
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PTC299 is an investigational new drug, which means it is being tested as a potential treatment for neurofibromatosis and for certain types of cancers and it has not yet been approved for sale by the U.S. Food and Drug Administration (FDA). PTC299 is currently being investigated in clinical trials in patients with neurofibromatosis type 2 (NF2), metastatic breast cancer, HIV-related Kaposi’s sarcoma, and other tumors. Additional clinical trials in patients with other types of tumors are planned.
NF2-related vestibular schwannoma tumor cells make high levels of a protein called vascular endothelial growth factor (VEGF). VEGF stimulates formation of new blood vessels that feed tumors with oxygen and nutrients, helping them to grow. Inhibiting VEGF may slow new blood vessel formation and also may slow tumor growth. Drugs targeting new blood vessel formation in tumors are currently available to treat cancers of the brain, lung, breast, colon, rectum, liver, and kidney. Some data is available to suggest that blocking VEGF may be useful in NF2.
PTC299 may offer a new approach to antitumor therapy in NF2. It is designed to block the production of tumor-related VEGF only and not the VEGF necessary to maintain the growth and function of normal blood vessels. In addition, unlike some available drugs that block or bind to VEGF and must be taken by intravenous injection, PTC299 is taken by mouth.
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What information is currently available about the safety and efficacy of PTC299? |
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Short duration, early phase clinical trials in healthy volunteers and patients with cancer have evaluated the safety of PTC299. Results from these trials show that symptoms observed in people receiving PTC299 have been infrequent, mostly mild to moderate, and not considered to be likely caused by PTC299, even at higher doses than those being used in the PTC299 clinical trial in NF2.
The available efficacy information for PTC299 has been derived from animal experiments. In those experiments, PTC299 decreased the amount of VEGF made by tumors. In addition, PTC299 slowed or stopped the growth of tumors or caused them to shrink.
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What is the purpose and design of the PTC299 clinical trial in patients with NF2? |
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The study is testing PTC299 to see if the drug is safe and can slow the growth of NF2-related vestibular schwannomas and can improve NF2-related hearing loss in NF2 patients.
Participants take PTC299 by mouth twice per day. Each patient receives the drug continuously for up to 48 weeks. MRI scans, hearing tests, and blood tests are conducted before the first dose and every 8 weeks during the course of treatment.
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Why may patients consider participating in the trial? |
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NF2 patients who have discontinued all therapies for the treatment of NF2 for more than four weeks may consider participating in a trial of an oral medication.
As with other clinical trials, study participants have the opportunity to have their disease closely monitored by NF2 experts, and contribute to medical research and the broader understanding of NF2.
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Who is eligible to participate in the trial? |
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To be eligible for this trial, patients must be at least 18 years old, have a diagnosis of NF2 and a vestibular schwannoma that is getting larger or causing hearing loss. Women must not be pregnant or breastfeeding. In addition, patients must not have been previously treated with bevacizumab or another anti-angiogenic therapy. Other eligibility requirements will be explained at the trial site.
Before patients can participate in the trial, the medical researchers will discuss its details. Potential participants must sign a document called an informed consent form, indicating a willingness to participate and to follow the study requirements. This document explains the trial in great detail to allow patients to assess the risks and benefits of participation. A copy of the informed consent form is provided to each potential participant.
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Will there be any cost to participate in the trial? |
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Participants will not pay for PTC299 or laboratory tests that are needed to complete the trial. However, some costs associated with routine medical care may be billed to participants’ insurance providers. Once enrolled, participants may be eligible to receive support for travel costs.
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What did the recent study in NF2 published in The New England Journal of Medicine show? Why is it important? |
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This clinical trial included 10 patients with NF2 and growing vestibular schwannomas, who were not candidates for surgery or radiation treatment. All of the patients received bevacizumab approximately every 2 weeks intravenously (by vein). The average duration of treatment was 12 months.
The data showed that blocking VEGF improved hearing in some patients with NF2 and was associated with a reduction in the volume of most growing vestibular schwannomas. These results are important because the study was the first to demonstrate that blocking VEGF has the potential to provide clinical benefit to patients with NF2.
The study was published by The New England Journal of Medicine on July 23, 2009 and is available here:
http://content.nejm.org/cgi/content/short/361/4/358.
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