(HealthNewsDigest.com) – PHILADELPHIA, Feb. 27, 2017 — People with hemophilia require regular infusions of clotting factor to prevent them from experiencing uncontrolled bleeding. But a significant fraction develop antibodies against the clotting factor, essentially experiencing an allergic reaction to the very treatment that can prolong their lives.
Researchers from Penn Dental Medicine, University of Florida, and University of North Carolina have worked together to develop a therapy to prevent these antibodies from developing, using clotting factor produced in plant cells to teach the body to tolerate rather than block it. Successful results from a new study of the treatment in dogs give hope for an eventual human treatment. The work was published in the journal Molecular Therapy.
Professor Henry Daniell, Director of Translational Research at Penn Dental Medicine is the senior author. Daniell’s patented plant-based drug production platform enabled the production of human clotting factor IX in lettuce leaves. Daniell has shown previously that the plant cell wall protected the clotting factor from digestion in the stomach, while being successfully presented to the body’s immune system. The modified plants were grown in a FDA-approved hydroponic facility (Fraunhofer).
Hemophilia B dogs were fed freeze-dried lettuce powder/clotting factor twice a week for ten months — spiked with bacon flavor and sprinkled on their food. Observing no negative side effects of the treatment in the initial study, the team conducted a more robust study in eight dogs for >300 days. After four weeks, all dogs received weekly injections of clotting factor IX, which continued for eight weeks.
All four of the dogs in the control group (that did not receive lettuce powder) developed significant levels of antibodies against clotting factor IX, and two had visible anaphylactic reactions that required the administration of antihistamine. In contrast, three of the four dogs in the experimental group had only minimal levels of one type of antibody, IgG2, and no detectable levels of IgG1 or IgE. The fourth dog in the experimental group had only a partial response to the treatment, which the researchers believe to be due to a pre-existing antibody to clotting factor IX.
Overall, levels of IgG2 were 32 times lower in the treated dogs than in the controls.
In addition, the dogs showed no negative side effects from the treatment, and blood samples taken throughout the experiment (>300 days) revealed no signs of toxicity from the treatment.
“The results were quite dramatic,” Daniell said. “We corrected blood clotting time in each of the dogs and were able to suppress antibody formation as well. All signs point to this material being ready for the clinic.”
The next steps for the research team include additional toxicology and pharmacokinetics studies before applying for an Investigational New Drug application with the FDA—a step they hope to take before the end of the year, supported by the NIH SMARTT program, designed to accelerate translation to research. This research is supported by NIH’s National Heart, Lung and Blood Institute and Novo Nordisk