Competitors abound to produce key medical isotope

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21 Feb 2019 in Politics & Policy

After decades with no US producer, a plethora of hopefuls vie for a share of the molybdenum-99 market.

David Kramer

David Kramer

University of Missouri Research Reactor
The 10 MW University of Missouri Research Reactor supplies neutrons that are used in the production of molybdenum-99. Credit: University of Missouri System, CC BY-NC-ND 2.0

The once-desolate field of producers of the most widely used medical radioisotope in the US is about to get crowded. Less than a year after NorthStar Medical Radioisotopes became the first US supplier of molybdenum-99 in three decades, at least five competitors, aided by funding and facilities from the Department of Energy (DOE), are taking steps to begin commercial production.

With a half-life of 66 hours, 99Mo decays to technetium-99 metastable, which has a six-hour half-life. The gamma-emitter 99mTc is used in 80% of all nuclear medical procedures, mainly as a tracer in bone, brain, and heart imaging. The US, which accounts for about half the world demand for 99Mo, has for decades relied on a small number of foreign reactor sources of supply. Until ceasing production in 2016, the National Research Universal reactor in Ontario, Canada, satisfied about half of US demand, using weapons-grade uranium supplied by DOE.

To encourage domestic production of 99Mo without the use of highly enriched uranium, DOE’s National Nuclear Security Administration (NNSA) has awarded several $25 million grants since 2010 to support private development. A new round of awards, to NorthStar and three other companies of up to $15 million each, was announced on 20 February. Congress had appropriated that $60 million over the last two fiscal years; recipients must provide matching funds.

“Several thousand” patients have now been treated using NorthStar-generated 99Mo, says Stephen Merrick, CEO of the Wisconsin firm. Its process involves the capture of neutrons by natural enriched 98Mo isotope targets. Merrick says NorthStar could currently supply up to 10% of the US market if a global shortage develops, as has frequently occurred in the past.

Thyroid imaging
Diagnosticians use technetium-99m to, among other things, reveal thyroid abnormalities. Inset A shows a healthy thyroid; the others show various conditions. Credit: P. Perros, PLOS Med. 2, e370, 2005

NorthStar also is developing an accelerator-based production method that involves knocking a neutron from 100Mo. The first of a half dozen accelerators will be installed next year. Taken together, NorthStar will have the capacity within several years to supply two-thirds of US demand, Merrick says. In addition to the new $15 million infusion, the company has already received two $25 million NNSA grants, one each for the reactor and accelerator processes.

But NorthStar may not have a monopoly on the US market for long. Niowave, a spinoff of the DOE-funded National Superconducting Cyclotron Laboratory founded by former NSCL scientist Terry Grimm, also received a $15 million NNSA award. The Lansing, Michigan, company says it has demonstrated the production of small quantities of 99Mo, strontium-89, iodine-131, and xenon-133 using a superconducting electron accelerator. The iodine and xenon isotopes are used as imaging agents, while 89Sr is used to help relieve bone pain that can occur with certain types of bone cancer.

Niowave’s process fissions low-enriched uranium targets with accelerator-generated neutrons. The company developed its linear accelerator technology with support from three Small Business Innovation Research grants from DOE. It has supplied superconducting accelerator systems for Brookhaven, Los Alamos, and Thomas Jefferson national laboratories and for the US Navy’s free-electron laser weapon program. Niowave plans to build a 40 MeV linac, an increase of about a factor of four over its existing machine. It expects to begin production in 2023 and to eventually be able to supply one-quarter of US 99Mo demand.

At least three other US companies—Northwest Medical Isotopes in Oregon, BWXT Technologies in Virginia, and Coquí RadioPharmaceuticals in Tennessee—are developing reactor-based approaches for 99Mo production. Northwest and Coqui plan to manufacture 99Mo by irradiating low-enriched uranium targets. That’s the traditional approach that’s been taken by the handful of other producers around the world.

Northwest, another $15 million NNSA award recipient, plans to use the University of Missouri Research Reactor, which also supplies neutrons for NorthStar’s current commercial process. The 10 MW facility is the largest university research reactor in the US and one of the last to be fueled with highly enriched uranium. Northwest also has an agreement to produce the isotope in Oregon State University’s research reactor, providing redundancy when the Missouri reactor is offline for maintenance. A partnership that includes several large health-care institutions, Northwest is aiming for commercial production no later than 2023, says CEO Larry Mullins.

NorthStar Mo-99 source vessels
Source vessels like these at a NorthStar facility are filled with molybdenum-99 and shipped to radiopharmacies. Credit: NorthStar Medical Radioisotopes

Coquí is proposing to build its own isotope-producing reactor, on DOE-donated land outside Oak Ridge, Tennessee. Coquí CEO Carmen Bigles says her company will have the capacity to satisfy one-third of US demand when it begins production in 2025. Its proposed open-pool reactor will be similar to the Open Pool Australian Lightwater research reactor, which also produces 99Mo. The high-assay low-enriched fuel for Coquí’s reactor will be supplied from NNSA’s nearby Y-12 National Security Site, the nation’s storehouse for highly enriched uranium.

Similar to NorthStar’s, BWXT’s process involves neutron capture by 98Mo targets. The company has an agreement to use Ontario Power Generation’s heavy water–moderated CANDU reactor for target irradiation. A BWXT spokesperson said the company hopes to introduce its product in 2021, subject to regulatory approvals. It hasn’t received NNSA funding.

The fourth awardee in the 20 February announcement, SHINE Medical Technologies, has already received $25 million from NNSA. The company is pursuing a hybrid production process in which a beam of deuterium nuclei from an accelerator fuse with tritium. The resulting 14 MeV neutrons fission low-enriched uranium targets to produce 99Mo.

For its tritium requirements, SHINE has also contracted with Ontario Power Generation, which extracts tritium from heavy water. Construction of SHINE’s main production facility in Wisconsin is planned to commence in the spring. At full capacity, it will be able to meet one-third of world 99Mo demand, according to company press releases.

NNSA also funds national laboratory R&D in support of all six companies’99Mo programs, as well as those of two others: Global Medical Isotope Systems in Nevada and Magneto-Inertial Fusion Technologies in California.

One prospective 99Mo producer, a joint venture between General Atomics and Canada’s Nordion, ended last year. It had been awarded NNSA funding.

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