It wasn’t that long ago when the drug companies firmly held that genetics played no significant role in how medicines worked. But that changed in 1988 when researchers at the National Institutes of Health reported that between five and ten percent of white people had a recessive gene that made them poor metabolizers of an antihypertensive drug. This finding extended to other drugs as well.
With the anti-leukemia drug, 6-Mercaptopurine, some children who were fast metabolizers needed fifty times the normal dose to have the desired effect, while others, very slow metabolizers, could tolerate only one-fifteenth the normal dose without sustaining liver toxicity. It is now known that human genetic variability holds optimal individual safety and efficacy bounds for all medications, from powerful antipsychotic drugs and everyday vitamins.
With 3-D printing, it’s possible to conceive that one day, drugs can be tailor made for patients, according to their pharmacogenomic profile. How soon that day arrives depends on knowing how a drug acts upon a gene or genetic pathway, and how an individual’s genome reacts to a single drug or drug combination. As that sorting out proceeds, not only are new medicines becoming more specific, but new indications are arising for older medicines because in some instances seemingly unrelated diseases have intersecting molecular pathways.
Two highly innovative areas in drug development are monoclonal antibodies and nanoparticle delivery systems. The first monoclonal antibody was licensed in 1986—made from fusing single antibody producing B cells of mice to human myeloma cells. The cancer cells kept dividing, and the antibody production kept pace. Since then, about thirty monoclonal antibody “biologics” have come into medicine, with names like Abagovomab, Cetuximab, and Zanolimumab—the “mab” suffix meaning monoclonal antibody. Because these molecules have specificity for particular human cell types, they can act as guided missiles carrying cytotoxins, radioisotopes, or fluorescent labels. There was much good news at this past September’s conference of the European Cancer Organization about single mabs and others in combination against deadly late stage melanoma, lung and kidney cancer.
Nanoparticles are about the same size of biomolecules—that is, on the one-billionth scale. (There are a billion nanoseconds in one second). They can be made from lipids, polymers, gold and silver, or other materials, and because of their high surface to volume ratio can carry nucleic acids, small molecule drugs and imaging agents on their surfaces. By giving them a positive charge, they are attracted to negatively charged cell membranes, which then allows these structures to be absorbed into a tumor cell’s body. By this means, nanoparticles also can cross the blood-brain barrier to attack glioblastomas.
There are so many promising uses for nanoparticles—for example, artificial antibiotics and vaccines, treating arterial plaque, controlled drug release, visualizing surgical margins—that “nanomedicine” is becoming a specialty in itself. In the United States much of the research funding has comes from the National Nanotechnology Initiative (1999).
The headquarters for the American Society for Nanomedicine is in Ashburn, VA.