· New Method for Producing Alpha-Emitting Bismuth-213 Patented
· ASCO Report Details 2006 Advances in Clinical Cancer Research
· Varian Medical Systems Acquires ACCEL Instruments

New Method for Producing Alpha-Emitting Bismuth-213 Patented

Alpha-emitting radioactive isotopes show enormous potential for targeted molecular therapy—but they are expensive and sometimes dangerous to produce. That is why Advanced Medical Isotopes Corp (ADMD), Kennewick, Wash, was quick to patent its new method of industrially producing actinium-225, the parent isotope of alpha-emitting bismuth-213. By offering actinium-225 in a portable “generator” form that pairs bismuth-213 with a monoclonal antibody, ADMD hopes to revolutionize targeted molecular therapy.

“The bismuth-213 is in a molecular cage and is pulled along by the monoclonal antibody, which is essentially a very large protein,” explains Robert Schenter, PhD, chairman of ADMD’s Scientific Advisory Board. “The molecule that holds the bismuth is very small, only about 30 or 40 atoms. The solution is injected into the patient, and the monoclonal antibody carries the bismuth to the tumor and attaches only to the cancer cell.”

Bismuth-213 is valued both for its ideal half-life of 46 minutes—parent isotope actinium-225, with a half-life of 10 days, can be shipped all over the world—and for being an alpha-emitter. “Alpha particles are very effective in killing cancer cells,” Schenter says. “You can kill a cancer cell with a single alpha particle. It has a lot of energy.” Alpha-emitters like the bismuth leave today’s beta-emitters in the dust, Schenter says. “It takes several hundred betas to kill a cancer. It takes only one alpha.”

Actinium-225 used to be produced by a notorious grandparent: uranium-233, more famous for its bomb-enhancing qualities than its therapeutic potential. A safer method involves irradiating Marie Curie’s radium, radium-226, with protons inside a cyclotron. But this process is expensive, resulting in a cost of around $2 million per curie, Schenter estimates.

So, the company developed its own method. “We use gamma rays to target radium-226,” Schenter says. “When a gamma particle hits the radium-226, a neutron is injected to make radium-225, which then decays into actinium-225. We feel that this is the best and least expensive way to make actinium, which is why our company has patented that approach.”

Bismuth-213 already is making headlines for its therapeutic potential, for both cancer and—as early animal studies performed at the Einstein Cancer Center, Philadelphia, and published in Scientific American suggest—fighting HIV. Schenter says, “These isotopes have started the next generation of cancer treatment.”

ASCO Report Details 2006 Advances in Clinical Cancer Research

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The second annual Clinical Cancer Advances 2006: Major Research Advances in Cancer Treatment, Prevention, and Screening report from the American Society of Clinical Oncology (ASCO), New York City, is now available for free online. ASCO’s 2006 report summarizes six major advances in clinical cancer research and 26 other notable advances across 10 cancer types; ASCO also makes recommendations to accelerate the pace of clinical cancer research.

“Over the past year, we’ve seen significant advances in targeted therapies for hard-to-treat cancers, a vaccine to fight cervical cancer, and new tools in the fast-growing field of personalized medicine,” Gabriel Hortobagyi, MD, ASCO president and chair of breast medical oncology at the University of Texas MD Anderson Cancer Center, Houston, said in a press release. “But if we hope to realize the potential of extraordinary new scientific knowledge and accelerate the pace of discovery, we need a new national commitment to cancer research, including greater funding.”

Some of the report’s highlights include a section showcasing advances in research on the treatment of advanced HER-2-positive breast cancer, which constitutes 20% to 25% of all breast cancer cases; studies have shown that the addition of lapatinib to chemotherapy controls cancer growth more effectively than chemotherapy alone. In the area of central nervous system tumors, the addition of a course of chemotherapy to traditional radiotherapy was found to increase the length of time before cancer progressed.

The ASCO report also notes that, although HIPAA compliance is important to protect patient safety, it has a negative impact on cancer research, delaying or limiting access to human biospecimens needed for large-scale studies. Cancer registries are observing sharp declines in patient participation since HIPAA was enacted—in some cases, a decrease of 85% was reported.

Varian Medical Systems Acquires ACCEL Instruments

In January 29, Varian Medical Systems, Palo Alto, Calif, completed its acquisition of ACCEL Instruments GmbH, Cologne, Germany, for $30 million. The purchase of ACCEL, a privately held supplier of proton-therapy systems, will enable Varian to offer products for delivering image-guided, intensity-modulated proton therapy. Medical Imaging spoke with Spencer Sias, vice president of corporate communications and investor relations at Varian, about the company’s plan to usher proton therapy into the US market.

MI:  Why did Varian choose ACCEL?

Spencer Sias

Sias: ACCEL has very good technology—specifically, superconducting magnets, which will allow us to make smaller, more affordable centers, and also scanning beam technology, which will support intensity-modulated proton therapy. Those technologies make ACCEL the type of company we want to work with.

MI:  How will ACCEL’s products be integrated with Varian’s?

Sias: Proton-therapy centers are really separate from standard radiotherapy centers. The software is integrated already, though. For example, Varian sells treatment-planning software for radiotherapy, and that software supports proton therapy. Also, our informatics software for managing information, images, etc in the radiation oncology center also would support proton therapy. Furthermore, we have beam-shaping technologies and other technologies that will be applicable to proton therapy.

MI:  What are the clinical indications most applicable to proton therapy?

Sias: Proton therapy is expected to apply to between 10% and 20% of patients. The ideal patients for this would be pediatric cases where you’re trying to absolutely minimize the long-term impact of radiotherapy and to reduce the chances of secondary cancers.

MI:  Do you have any statistics on usage or cure rates?

Sias: No, because it’s still in the early days. The market for it last year was about $250 million, though.

MI:  What market is Varian hoping to serve?

Sias: We think that this can apply to large institutional centers, but also maybe regional centers. The proton-therapy center can probably be put up for as little as $30 million. People have been used to thinking about these centers as costing in the range of $150 million, but with technology improving and reducing in size, we think we can make it affordable for large regional centers and community centers.

MI:  Have there been any advances in proton-therapy technology that have made it more viable?

Sias: People are thinking in terms of single-room centers as opposed to multi-room centers, and that’s a significant incentive to reduce cost.

MI:  Where is proton therapy headed?

Sias: We think we can build this into a very viable part of the services and products that we offer. We think it’s going to become a mainstay in radiotherapy over time, and we’re looking forward to making that happen.