Of the six volunteers who became seriously ill during a drug trial last week, four, mercifully, seem to be beginning to recover, while two are still critical, according to the most recent BBC news story. It’s still too early to be sure what went so tragically wrong; there are informative articles, with some informed comment, on the websites both of New Scientist and Nature. What we should learn from this is that even as medicine gets more sophisticated and molecularly specific, many things can go wrong in the introduction of new therapies. The length of time it takes new treatments to get regulatory approval can be frustratingly, agonisingly long, but we need to be very careful about the calls we sometimes hear to speed these processes up. The delays are not just gratuitous red tape.
The drug behind this news story was developed by a small, German company, TeGenero immunotherapeutics. It’s a monoclonal antibody, code-named TGN1412; a protein molecule which specifically binds to a receptor molecule on T-cells, a type of white blood cell which is central to the body’s immune response. The binding site – code-named CD28 – is a glyco-protein – a combination of a protein with a carbohydrate segment – which provides the signal to activate the T-cells. What’s special about TGN1412 is that the action of this drug alone is sufficient to activate the T-cells; normally simultaneous binding to two different receptors is required. It’s as if TGN1412 overrides the safety catch, allowing the T-cells to be activated by a single trigger. It’s these activated T-cells that then carry out the therapeutic purpose, killing cancer cells, for example.
Few people have connected these events with bionanotechnology (an exception is the science journalist Niels Boeing in this piece on the German Technology Review blog). There are now a number of monoclonal antibody based drugs in clinical use, and they are not normally considered to be the product of nanomedicine. But they do illustrate some of the strategies that underlie developments in nanomedicine – they are exquisitely targeted to particular cells, they exploit the chemical communication strategies that cells use, and they increasingly co-opt biology’s own mechanisms for clinical purposes. Biology is so complex that it’s always going to spring surprises, and the worry must be that as our interventions in complex biological systems become more targeted, so the potential for unpleasant surprises may increase. Whenever one hears blithe assurances that nanotechnology will soon cure cancer or arrest ageing if only those bureaucratic regulators would allow it, one needs to think of those two men struggling for their lives in a North London hospital. There may be good reasons why the pace of innovation in medicine can sometimes be slow.