The Cre-loxP Patent Dispute: "The Mouse That Prompted a Roar"

The Mouse That Prompted a Roar: Patent Disputes Over Cre-loxP Technology

Introduction to the Patent Dispute

  • Core Issue: DuPont's patent restrictions on the Cre-loxP gene manipulation technology in mice have sparked widespread protests among prominent researchers and institutions.

  • Impact on Researchers:

    • Jamey Marth, a geneticist at the University of California, San Diego, is now required to seek approval from E. I. du Pont de Nemours and Co. (DuPont) before sharing Cre-loxP engineered mice, leading to "heart-wrenching" decisions to withhold these valuable research tools from colleagues.

  • DuPont's Conditions for Use: The company insists that researchers using Cre-loxP mice must:

    • Acknowledge DuPont's proprietary rights to the animals.

    • Share a portion of any commercial profits derived from discoveries made using the technology (royalties).

    • Distribute the animals only to other researchers whose institutions have formally agreed to these terms.

  • Additional DuPont Patent Control: DuPont also holds an exclusive license for the "Harvard oncomouse," a tumor-prone animal critical for cancer research, and is also seeking to control its distribution and use.

  • Broader Context: While the Cre-loxP technique has become a "lightning rod" for concern, it is not the only basic research tool whose use is constrained by patent rights.

  • NIH's Protest: Harold Varmus, Director of the National Institutes of Health (NIH), has formally protested DuPont's policy, citing the "incredible burden for the individual investigator" due to administrative requirements. He fears that legal complications could "slow things down, make research unattractive, and turn people off." Varmus has established a panel to examine these and other restrictions on the sharing of research materials.

The Cre-loxP Technology Explained

  • Inventor: Geneticist Brian Sauer, a former DuPont employee now working at NIH's National Institute of Diabetes and Digestive and Kidney Diseases.

  • Initial Reception (1985): Sauer's initial presentation of the Cre-loxP system at a biotech poster session in San Francisco received little attention ("Not many even stopped by").

  • Mechanism - "Molecular Scissors":

    • The technique adapts a natural gene-splicing system found in a bacteriophage (P1), a virus that infects bacteria, for use in eukaryotic (complex) cells.

    • It relies on two genetic elements from the P1 bacteriophage:

      • A gene named cre: This gene expresses an enzyme called Cre, which is not naturally present in higher organisms.

      • A specific DNA sequence called loxP.

    • Function: The Cre enzyme acts like an editing machine. When it encounters two loxP sites within a stretch of genetic code, it precisely excises the intervening DNA segment, along with one of the loxP sites, and then seamlessly reattaches the remaining DNA ends.

    • Application: Sauer's innovation was to place loxP signals on either side of a target gene. By introducing the Cre enzyme, the target gene could be selectively snipped out. This system was proven effective in eukaryotic cells and eventually in mice.

  • Patent Status: Sauer and DuPont filed for a patent on using Cre-loxP to modify DNA in eukaryotic cells in 1984, which was granted in 1990.

  • Rapid Adoption and Improvement:

    • Since 1990, Cre-loxP mouse technology has gained significant traction and has been substantially improved in taxpayer-funded laboratories by independent scientists.

    • Key Contributors: Jamey Marth, Klaus Rajewsky and Werner Müller (University of Cologne), Heiner Westphal (NIH), Susumu Tonegawa and colleagues (Massachusetts Institute of Technology), among others.

    • Primary Value: Its main utility lies in creating "conditional mutants"—mice where a specific gene can be precisely targeted for deletion only in particular cells that express the Cre enzyme. The technology is also used to generate other types of genetically engineered mice, including straightforward "knockouts."

  • Growing Importance: Klaus Rajewsky notes that published papers do not yet fully reflect the expanding significance of this technology, partly because developing and analyzing conditional mutants is a time-consuming process.

    • The Volkswagen Foundation is funding a new program on conditional mutagenesis in Germany; at a recent meeting in Cologne, 15 out of 30 attending groups reported using Cre-loxP technology.

    • Arthur Beaudet (Baylor College of Medicine), who chairs NIH's mammalian genetics peer-review section, describes the interest as "huge."

    • Thomas Caskey (Merck & Co.) predicts "extremely broad applications" for understanding gene function, envisioning shared libraries of mice expressing cre in various cells, allowing researchers to breed them with their own loxP-targeted genes to inactivate genes in specific tissues.

DuPont's Licensing Policies and Institutional Responses

  • "No-Cost Research Licenses": DuPont aims to control the technology through these licenses, which require institutions to agree that their researchers will only share the mice with other licensees. There is also a potential mandate to pay "unspecified royalties" on any commercial discoveries resulting from the Cre-loxP system.

  • Commercial Licenses: For commercial entities, licenses are considerably more expensive, potentially exceeding $100,000.

  • Adoption Rate: Approximately 70 institutions have signed these research licenses.

  • Howard Hughes Medical Institute (HHMI) Acceptance: HHMI, a prominent research organization, has signed the agreement, meaning all its investigators (including Jamey Marth) must adhere to DuPont's terms.

    • HHMI's Rationale (Maxwell Cowan, Chief Scientific Officer): HHMI believed it was "the right thing to do" given that many of their investigators were already using the technology. They recognized DuPont's valid patent rights and the alternative would have been to halt numerous research projects by instructing investigators not to use Cre-loxP mice. Cowan acknowledged a "difference of opinion with Harold Varmus" on this issue.

Reactions and Opposition to Licensing Restrictions

  • NIH's Stance:

    • The NIH has not signed an agreement but is engaged in "friendly negotiations" with DuPont.

    • DuPont currently permits NIH researchers to continue using animals provided by Brian Sauer years ago, before the company began actively licensing all nonprofit institutions.

    • Varmus's Formal Protest: In a letter dated March 28 to DuPont's president, John Krol, Varmus asserted that the restrictions "will seriously impede further basic research and thwart the development of future technologies that will benefit the public."

    • Broader Critique: Varmus also expressed concern about university and NIH scientists attempting to patent basic research tools, stating, "There are investigators here who would like to seek intellectual protections for everything they do, and I don't find it very appealing."

    • Planned Meeting & Panel: Varmus, who utilizes transgenic mice in his own lab, scheduled a meeting with DuPont executives in late July. He also created a small panel, including gene patenting experts Rebecca Eisenberg (University of Michigan) and John Barton (Stanford University), to advise NIH on responding to "reach-through" provisions (claims on future, yet-to-be-made discoveries).

  • Widespread Objections:

    • Many researchers in the U.S. and Europe are subtly protesting DuPont's conditions.

    • Bruce Alberts, president of the U.S. National Academy of Sciences, highlighted Cre-loxP restrictions as an example of commercial barriers to basic research.

    • Klaus Rajewsky characterized DuPont's license terms as "much too strong for a basic technology."

    • One unnamed researcher admitted to ignoring the rules and sharing mice with trusted peers.

The Jackson Laboratory Standoff

  • Key Player: The Jackson Laboratory in Bar Harbor, Maine, is the largest breeder and distributor of lab animals in the United States.

  • Refusal to Sign: It has been in a two-year standoff with DuPont, refusing to sign an agreement due to concerns that DuPont's terms would impose excessive legal constraints on the lab and its clients.

  • Consequences for Research: As a result of this refusal, The Jackson Laboratory neither accepts nor distributes Cre-loxP mice, making these essential research animals scarce.

    • Klaus Rajewsky described this as "the most serious practical problem we have at the moment."

    • Arthur Beaudet noted that with NIH making a "huge investment in developing these mice," the stalled negotiations could have "broad implications" for biomedicine.

Conclusion and Outlook

  • Signs of Potential Compromise: Robert Gruetzmacher, DuPont's licensing executive, indicated a willingness to adapt, stating, "We continue to modify our license to make it better. We are learning to make concessions to make it work."

  • Hope for Resolution: Many researchers are optimistic that the meeting between Harold Varmus and DuPont executives will resolve the stalemate.

  • Varmus's Broader Objective: Beyond the immediate dispute, Varmus aims to engage the scientific community in a larger discussion to "rethink what a patent is for" throughout the year.