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Suspended Resveratrol Clinical Trial: More Details Emerge

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Published: May 6, 2010 11:37 pm

Representatives from Sirtris Pharmaceuticals, developer of a proprietary formulation of resveratrol called SRT501, confirmed yesterday that a clinical trial of the drug in multiple myeloma patients was suspended because several patients developed kidney failure.  The Myeloma Beacon reported the trial's suspension in an article earlier this week.

Sirtris representatives also have told the Beacon that all patients who experienced kidney failure during the trial were being treated with only SRT501 when their kidney problems developed.

However, it is still uncertain whether the kidney failures were simply a manifestation of the underlying myeloma, or if they were related to the resveratrol treatment.

“We still are investigating. We do not know all the details, and we have a lot of data to review,” said Dr. Eric Jacobson, Chief Medical Officer of Sirtris, in an interview with The Beacon. “But we think it likely that the drug itself is not directly toxic to the kidneys.”

“This was most likely a manifestation of the underlying myeloma.” Dr. Jacobson noted that SRT501 has not caused a single case of kidney failure in any of the previous trials of the drug, which involved some 340 healthy persons, colon cancer patients, and diabetes patients. “We have never seen another case of [kidney] failure except in this myeloma study.”

Sirtris is a subsidiary of the pharmaceutical company GlaxoSmithKline.

SRT501 is a formulation of resveratrol, a molecule found in small quantities in the skin of red grapes and in red wine. Resveratrol is thought to be the source of red wine’s reported health benefits.

According to Sirtris representatives, the resveratrol in SRT501 is from a plant-based source and is micronized, or milled into very small uniform particles, to maximize uptake into the body.

Previous studies have indicated that resveratrol may be effective at killing cancer cells, including multiple myeloma cells. Research has also shown that it may make other chemotherapy drugs, like Velcade (bortezomib) and thalidomide (Thalomid), more effective.

Scientific evidence for these claims has been controversial and confined mostly to the laboratory. The SRT501 trial was the first attempt to determine the effectiveness of resveratrol in treating multiple myeloma patients.

Participants in the SRT501 trial received five grams of the drug once per day on 20 days of a 21-day cycle. Testing for disease progression was scheduled after every two cycles.

Patients with stable results after two cycles continued with the SRT501 treatment alone, while those who experienced disease progression received supplemental treatment with Velcade.

The study was suspended before recruitment was complete due to safety concerns. More specifically, five of the 24 patients (21 percent) developed cast nephropathy, or “myeloma kidney.” In all cases, the cast nephropathy developed while the patients were only receiving SRT501.

According to Dr. Nelson Leung, a kidney specialist at the Mayo Clinic in Rochester, Minnesota, cast nephropathy is a common complication of multiple myeloma. It occurs when excess protein blocks the kidney, resulting in kidney failure, and it affects 15 to 30 percent of myeloma patients.

The exact cause of cast nepropathy is not known, but free light chains -- molecules in the blood overproduced by people with myeloma -- are thought to play a key role. "Dehydration and high calcium levels have also been associated with cast nephropathy," said Dr. Leung.

Patients in the SRT501 trial were required to have normal kidney function prior to the trial in order to participate in it. Due to the relatively high dose of SRT501 used in the study, however, some participants experienced nausea and vomiting, which could have led to dehydration. Sirtris believes this may have been a factor in the kidney failure seen in the clinical trial.

“In a patient who was prone to the renal failure from their high light chains, ” said Dr. Jacobson, “dehydration could have tipped the balance. That could have been an indirect precipitating cause of the kidney problems.”

Dr. Jacobson also noted that all of the patients in the trial had experienced at least one treatment failure for multiple myeloma, and the majority of participants had failed several treatments.

Nonetheless, there is some concern that the dose of resveratrol used in the study could have contributed to the safety issues. Dr. Bharat Aggarwal, Professor of Cancer Research at the University of Texas M. D. Anderson Cancer Center, expressed surprise at the amount of SRT501 given to the patients.

“I am not surprised that they had toxicity. It is too high a dose,” said Prof. Aggarwal, who has studied resveratrol in myeloma cells but is not involved in the SRT501 study.

“Phase 1 clinical trials with resveratrol showed that even when tested in high doses, it was safe,” Prof. Aggarwal added. “Whether SRT501 has a different profile of toxicity, is not clear.”

Sirtris, however, believes that the high dose is necessary. “We are using an extraordinary amount of resveratrol because of what we know about the amounts that are probably required to show a biological effect,” said George Vlasuk, CEO of Sirtris, in an interview yesterday with The Beacon. The daily five gram dose of SRT501 used in the suspended trial also was a common dose used in other SRT501 trials.

Representatives from Sirtris emphasized in their discussions with the Beacon that the SRT501 myeloma trial has not been stopped. Although new participants are not being recruited at this time, evaluation of SRT501 and its efficacy will continue.

“The trial was not stopped. The trial remains active,” said Vlasuk. “We are simply, out of an abundance of caution, trying to understand if SRT501 is actually providing a benefit to these patients.”

“If we determine that’s the case, or at least that it doesn’t have an adverse safety finding, we will continue with this trial.”

Company representatives also emphasized that, despite news reports to the contrary, Sirtris has not made a decision to halt overall development of SRT501.

It is not clear what implications, if any, the safety issues during the SRT501 trial may have for the use of dietary supplements containing resveratrol. SRT501 is a very pure form of the compound, and the five gram dosage is higher than the amounts contained in most supplements.

When Dr. Aggarwal was asked whether he would recommend that certain myeloma patients take resveratrol supplements, he said, “We have no data in patients to suggest that resveratrol helps.”

Update (November 30, 2010) - GlaxoSmithKline has decided to halt all further development of SRT501.  See the related Myeloma Beacon news story.

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  • David Anders said:

    Nice piece of investigative reporting here. One thing to keep in mind - I believe SRT501, while being micronized into very small particles to increase absorbtion, is also delivered with cyclodextrin which also increases absorbtion into the body - According to Sirtris, 5 times more absorbtion than standard pure resveratrol. In sum you have 5 grams of resveratrol which are 5 times more absorbable into the body - This could equate to 25 grams of resveratrol per day - which would equate to 50 500 mg. pills of pure resveratrol per day.

  • hi there said:

    It still seems like there might be good news if most wanted to continue to take SRT501. The colon cancer SRT501 trial ended 4 months ago, but no word on how effective that was.

    By the way, the SRT 501 diabetes trial only went up to 2.5g/day and was found to be effective.

    Also, while SRT501 is supposedly 5 times as potent as plain resveratrol, I don't think it is correct to assume it is the same as taking 25g of pure resveratrol.

  • Beacon Staff said:

    Thanks, David, and "hi there" for your comments. We weren't told during our discussions with Sirtris about cyclodextrin being part of the SRT501 formulation, so that's some interesting additional information. As for the dosing of SRT501 in the diabetes trials done with the drug, it appears that both 2.5 and 5.0 grams per day were tested. One trial tested 2.5 and 5.0 gram doses of SRT501 taken once per day. Another trial tested the same doses, but split across two doses per day (i.e., 1.25 grams twice daily, and 2.5 grams twice daily). This press release from Sirtris has more information on those trials.

    Again, thanks for your comments and additional information.

  • hi there said:

    Thank you for correcting my mistake. I hope we will hear positive results regarding the completed SRT501 study on colon/liver cancer and that the multiple myeloma trial will also end up being successful. If some continued taking SRT501, maybe there is good news. Maybe...

  • G Alvarado said:

    As Dr. Aggarwal notes, it is likely that SRT501 has a different toxicity level, and the dosage administered (5 grams) played a part in the kidney failure. Sirtris should reconsider the formulation and delivery system. It's been widely reported that intraoral administration of resveratrol makes it more bioavailable. In consequence, it doesn't require such high dosages in order to attain biological effects. They could learn a thing or two from nutraceutical companies that have already succeeded in producing intraoral resveratrol in the form of melts, lozenges, sub-linguals and sprays.

  • W K TAN said:

    I took resveratrol (brand witheld) for a week on 2000mg per day.
    When I went for a normal blood test my potassium went up to 6.5. Immediately send to A&E. Flushed out the potassium and on 5th day took 2 again and it went up again. I am a CKD, probably due to high potassium level cautioon must be taken to administer this supplement.

  • Clark said:

    Looking like my cat has liver cancer. Giving him 500 mg of Biotivia Transmax resveratrol throughout the day with food. He is acting absolutely fine other than a bloated belly from an ascites side effect from the tumor. I'm just taking a shot at lengthening his life with resveratrol. Does anybody think I could be doing more harm than good? I don't want to cost him any time.

    Thanks for any thoughts.

  • Anonymous said:

    I appreciate the time you spend researching and deciphering scientific jargon to translate it into more readily understandable writings. The thing that struck me about this scientific clinical trial of resveratrol was that they used a mega-dose of resveratrol [5 gm/day]. I think sometimes they set up these trials of natural substances in a way that is designed to fail so that they can scare people away from using them.

  • Debra Clay said:

    I just went through Cemo / Stem Cell Transplant for MM. Released from the hospital Sept.4 2010. I was in stage 3+. Didn't know if I would make it when I found out in Jan. But through prayer and good Dr's I pulled through and was able to go through Cemo/stem cell trans. I would like to get on some kind of live talk or email with others that are going through or been their people.

  • Beacon Staff said:

    Dear Debra,

    We're glad to hear that you were recently released from the hospital. We hope the stem cell transplant went smoothly and successfully holds off the return of your myeloma.

    You may be interested in checking out our Beacon Forums. Feel free to introduce yourself on the forum, read through other people's posts and experiences, and post any questions you may have. It's a good way to connect with other myeloma patients.

  • mark said:

    Its important not to provide misleading information to patients. This drug is not resveratrol, nor is it chemically similar (I worked with this agent in the lab). It was a novel compound that was supposed to activate the same pathways as resveratrol but is probably not a direct activator of the sirtuin pathway, as was recently argued in a JBC article. So rather than frighten patients who are possibly taking a benign nutritional supplement, you should clarify that this trial has nothing to do with resveratrol as it is sold in health food stores.

  • Beacon Staff said:

    Thank you, mark, for your comment.

    Everyone we spoke with at Sirtris, and many other knowledgeable people who are familiar with the chemistry of SRT501, have said publicly and on the record that SRT501 is absolutely and unequivocally resveratrol. It is derived from a plant source and milled extensively so that it is absorbed into the bloodstream more than standard resveratrol. But it is nevertheless still resveratrol -- not a "chemical cousin" or "chemical analog", as some people have tried to describe it.

    If you have information that conclusively demonstrates that SRT501 is actually chemically different than resveratrol, please feel free to share it with us.

    It is true, by the way, that Sirtris is developing other compounds that are intended to function similarly to resveratrol, but are not chemically identical to resveratrol. SRT501, however, is not one of those other compounds.

  • Dawn said:

    This form of resveratrol cannot be said to be truly "natural" given that it has been "milled extensively so that it is absorbed into the bloodstream more than standard resveratrol".

    In order to be patented as a medicine, a substance has to be changed from its natural state. Perhaps, therein lies the problem. There may be protective factors in the standard forms of resveratrol that have been altered through the "milling" process.

    Personally, I would prefer to use a natural or food-based form, over something that has been altered, chemically or otherwise - unless safety was clearly demonstrated. Health-giving foods tend to have track records of centuries, even millenia, of safe use.

    In some cases, it may be best not to mess with Mother Nature.

    I'm using standard resveratrol, and will continue to do so. It is important to understand that standard resveratrol and the clinically tested version are not the same substance. The clinical trial version has been altered through milling even if still technically "natural"; the other has not.

  • Judy Smith said:

    Does anyone have information on TKI 258? It is our understanding this drug is in trial at St. Louis University Oncology Dept. in St. Louis, Mo.