MEDICAL DEVICE INNOVATION - Medical Device Daily

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152 Nanotubes plus radiation may be the key to a kidney cancer cure By LYNN YOFFEE Medical Device Daily Staff Writer An introductory talk from the director of the Center for Nanotechnology and Molecular Materials at Wake Forest University’s (Winston-Salem, North Carolina) School of Medicine about the value of nanomaterials sparked an idea among researchers that may now lead to an effective kidney cancer cure. Researchers there have just reported using nanotubes to eliminate cancerous kidney tumors and insure that they don’t return. Nanotubes are injected into the tumors and heated with a laser to effectively kill tumors in nearly 80% of mice tested, suggesting a potential future cancer treatment for humans. “Our lab is interested in relationships between iron and cancer,” Suzy Torti, PhD, a professor of biochemistry at WFU School of Medicine, told Medical Device Daily. “We came to study nanotubes because of the proximity of the Nanotechnology Center. A talk by the director, David Carroll, got everybody here excited. These particles have some iron and that can be used as contrast agents and those were our initial thoughts, but it became clear that nanomaterials were useful for more than that.” The work, reported in the August issue of the Proceedings of the National Academy of Sciences (PNAS) reports how carbon-based multi-walled nanotubes (MWCNTs), which contain several nanotubes nested within each other, were injected into tumors and then zapped with a 30-second dose of near-infrared radiation. Rather than delivering the nanotubes systemically, Torti’s team injected them directly into tumors, so that “. . . they didn’t have to find the tumors. That was a first step – just proof that they can be tumor-ablative agents if you can get them to the right place at the right time. “Then we exposed it to a near infrared laser radiation,” she said. “When you do that, nanotubes begin to vibrate pretty fast, creating heat. It’s localized to where the infrared radiation hits the tubes causing death of tumor cells.” For the study, Torti’s team reported that mice who received no treatment for their tumors died about 30 days into the study. Those that received the nanotubes alone or had laser treatment alone survived for a similar length of time. Tumors disappeared for 80% of mice that received the MWCNTs combined with laser treatment. Nine months later, many of the treated mice remained tumor free. “Nanotubes are pretty efficient at absorbing light . . . a broad absorption spectrum relative to other materials,” Torti said when asked why she chose nanotubes rather than another nanomaterial. “They can also absorb nearinfrared radiation. They’re pretty efficient at absorption MEDICAL DEVICE INNOVATION 2010 and reduce the amount of laser light needed to excite them.” Torti and her colleagues chose to try the treatment on kidney tumors because, “People have tried radio frequency ablation, which is a similar idea. A tip is inserted into the kidney to generate heat. But there are shortcomings. Although ablation is successful, the probe is not the best; there is seeding of tumors along the tumor trace. Using MWCNTs plus near-infrared radiation provides more diffuse heating.” Thermal ablation treatments for human tumors currently include radio frequency ablation, which applies a single-point source of heat to the tumor rather than evenly heating the tumor throughout, like the MWCNTs can do. Torti said her team was able to watch the tumors shrink, day by day, until they disappeared. “Not only did the mice survive, but they maintained their weight, didn’t have any noticeable behavioral abnormalities and experienced no obvious problems with internal tissues,” she said. “As far as we can tell, other than a transient burn on the skin that didn’t seem to affect the animals and eventually went away, there were no real downsides – that’s very encouraging.” Torti’s team noted the thermal effects generated by MWCNTs had added benefits, beyond the ablation of cancerous tumors. “For example, hyperthermia can increase the permeability of tumor vasculature, which can enhance the delivery of drugs into tumors, as well as synergistically enhance tumor cytotoxicity when combined with chemotherapy or radiotherapy,” according to the PNAS article. The next step is to explore systemic delivery and use a “slightly less contrived system” so that kidney tumors are actually resident in the kidney, rather than a subcutaneous placement as was the case for this study, in order to move closer to clinical applications. The team will then begin toxicology and pharmacology studies. It’s unknown what happens to the nanotubes after they are used. Torti said she observed (anecdotally, but not reported) that a certain number do remain at the site. It’s not a bad thing, she said, because it provides an opportunity for retreatment with additional zaps of radiation if necessary. A grant from the National Cancer Institute (Bethesda, Maryland) and a private donation will keep the wheels turning on this research project for several more years. Torti estimates that it would take at least “a few more years” of work to test the new therapy before human trials could begin, “even if everything worked remarkably well.” (This story originally appeared in the Aug. 4, 2009, edition of Medical Device Daily) To subscribe, please call MEDICAL DEVICE DAILY Customer Service at (800) 888-3912; outside the U.S. and Canada, call (404) 262-5547. Copyright © 2010 AHC Media LLC. Reproduction is strictly prohibited.
MEDICAL DEVICE INNOVATION 2010 New contraceptive may prevent HIV transmission, pregnancy By AMANDA PEDERSEN Medical Device Daily Staff Writer Women may someday have a new birth control option designed to not only prevent unplanned pregnancy but also block the transmission of the HIV virus. Researchers from Weill Cornell Medical College (New York) have published results showing that a new contraceptive device may do just that. The results are published in the latest issue of the journal AIDS. The new device is a vaginal ring that releases multiple types of non-hormonal agents and microbicides, which would prevent conception as well as sexually transmitted HIV infection, according to the researchers. Worldwide, there are about 5 million new infections and 3 million deaths a year due to HIV/AIDS. If proven successful in future clinical trials, the new device could empower women to effectively and conveniently protect themselves from unintended pregnancy and sexually transmitted infection. The ring may also someday represent a novel method to prevent sexually transmitted infections for those with aversion to currently available methods, with hormonally derived active agents, or with allergies to latex condoms, the researchers said. “This device is a new approach to birth control, because it avoids the long-term use of hormonal methods that have been associated with increased risk of certain cancers,” said Brij Saxena, MD, lead author and the Harold and Percy Uris Professor of Reproductive Biology and professor of endocrinology in the department of obstetrics and gynecology at Weill Cornell. “At the same time, this is the first device to simultaneously offer the possibility to prevent unintended pregnancy and HIV transmission.” Saxena told Medical Device Daily that long-term use of hormones has side effects. Women are always at risk for infection with HIV, he said, because it is transmitted during heterosexual contact. With this vaginal ring, “women will have control themselves to protect them [from] unintended pregnancy and HIV infection. He said the device can provide sustained release of both contraceptives and microbicide simultaneously in vitro at the concentration “which is efficacious and significantly below the toxic levels.” The vaginally inserted ring is incorporated with multiple antiviral drugs that prevent HIV infection and are timereleased over a period up to 28 days. The compounds tested are a newly developed anti-HIV agent, boc-lysinated betulonic acid, TMC120 (dapivirine), PMPA, and 3’-azido-3’- deoxythymidine (AZT or zidovudine), which, when combined, were found to block infection in human cells exposed to the virus in a laboratory setting. “No one has ever conquered a viral epidemic with treatment, so prevention is the most effective option. Ideally, an 153 HIV vaccine is the most desirable method, but that is not foreseeable in the near future,” said Jeffrey Laurence, MD, co-author of the study and attending physician at NewYork- Presbyterian Hospital/Weill Cornell Medical Center. “The next best thing would be something that would prevent infection and put the power in the susceptible female partner’s control. That’s the potential a device such as this can offer.” When asked to provide a crystal-ball guess as to when this new device might be available to women in the U.S., Saxena said it may be a couple of years. He said the compounds used in the device are natural materials that are already FDA approved for human use. However, the device itself may still be subject to FDA approval, he noted. “The combination of these antiviral drugs has proven to be potent agents that may block infection by the HIV virus,” Saxena said. The ring is also incorporated with compounds that prevent conception by arresting sperm motility, raising vaginal mucous viscosity, and sustaining the acidity of the vagina in which sperm do not survive. Traditionally, similar devices have used hormonal compounds that have been linked to increased risk of breast and cervical cancers, or spermicidal compounds that kill sperm, but may lead to irritation and inflammation, according to the researchers. Past findings published in the journal Contraception found the device to be highly effective in animal models and in laboratory testing. The study was supported by grants by the National Institutes of Health, International Partnership for Microbicides (Silver Spring, Maryland) and BioRings (New York). Collaborators on the study include Dr. Young Han and Mukul Singh, PhD, from Weill Cornell, Dr. Dingyi Fu and Dr. Premila Rathnam, formerly of Weill Cornell, and Sidney Lerner from BioRings. Saxena and Singh are vice presidents at BioRings and along with Lerner, president of BioRings, are coinventors and owners of U.S. and foreign patents on the technology used in this research. Cornell Research Foundation owns pending patent applications related to the research. (This story originally appeared in the June 2, 2009 edition of Medical Device Daily.) To subscribe, please call MEDICAL DEVICE DAILY Customer Service at (800) 888-3912; outside the U.S. and Canada, call (404) 262-5547. Copyright © 2010 AHC Media LLC. Reproduction is strictly prohibited.
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