Friday, November 22, 2013

tCDS and the First Glimpses of Human Enhancement Technology

Recently I have become increasingly aware of an emerging emphasis on using advances in biotechnology not just to cure disease but to improve the capabilities of healthy people. This ‘human enhancement’ phenomenon is cropping up in all sorts of places ranging from the military experimenting with ‘exoskeltons’ to give soldiers extra strength, to supposed life-style enhancing ‘nutraceuticals’, to the first attempts to increase longevity with drugs such as rapamycin. An interesting example was recently reported in a NY Times Magazine article “Jump-Starter Kits for the Mind” (1). This involved trans-cranial direct current stimulation (tCDS), a technique where small currents are applied to regions of the brain to improve memory or executive function. The idea is that the current stimulates neural tracts and such ‘exercise’ increases function, thus reflecting the well-establish neurobiological concept of Long Term Potentiation. As with it’s near relative, transcranial magnetic stimulation (TMS), a number of studies in ageing patients with impaired mental functions have claimed to detect benefits with use of tCDS. This has prompted investigators to examine the effects of tDCS in healthy people and, as described in the Times article, some positive results have been found. Apparently, since the technology is so simple, this has also prompted handy do-it-yourselfers to download how-to videos from YouTube and make tCDS devices for themselves. Since there have not yet been large-scale, blinded, controlled trials of tCDS or TMS the jury is still out on whether they really work. However, the enthusiasm with which they have been adopted by scientists and by some members of the public illustrate that there is tremendous interest in in the whole human enhancement thrust. 

Friday, November 15, 2013

FDA Doesn’t Make Sense Dealing With an Antisense Medication for Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is every parent’s nightmare. It’s an X-chromosome linked genetic disease that condemns young boys to paralysis and premature death. At present no therapy is available. However, recent research has indicated that certain types of antisense oligonucleotides can partially correct the genetic defect and at least slow the course of the disease. A small-scale clinical trial of an antisense molecule called Eteplirsen was recently completed by the biotech company Sarepta. The trial involved only twelve boys, but showed encouraging results. Sarepta then asked the FDA for ‘accelerated approval’ of the drug.  This is a relatively new mechanism whereby the FDA can conditionally approve new drugs for which there is a major unmet need, such as is the case in DMD. If the drug fails in subsequent larger-scale trials it would then lose approval. However, the FDA declined and has insisted on a full-scale placebo controlled trial of Eteplirsen prior to approval (1).

These decisions are always difficult. Clearly it is the duty of the FDA to make sure that approved medications actually work and are not a threat because of toxicity. However, stringent requirements for ‘classic’ clinical trials can keep good drugs out of the hands of needy patients for years. Similar situations have cropped up in the cancer therapy area where patients have pleaded for promising new drugs before these agents had completed formal clinical trials (2).
There is a lot of interest currently in adaptive clinical trials where advanced Bayesian statistics can be used to modulate trial design as information is accrued, rather than to be stuck with a rigid trial framework based on initial assumptions. One would think that the ‘accelerated approval’ process could be linked to trials of that type.

In this case it seems that FDA unnecessarily erred on the side of caution. While it is important to protect patients against possible toxicities of new drugs, in the case of Eteplirsen there was no evidence of toxic effects among the boys treated. Thus it seems likely that little harm would be done by letting additional patients be treated while more was being learned about the drug. 



Friday, November 8, 2013

Faith and Skepticism in Nanomedicine

As one who has intermittently toiled in the field of nanoparticle mediated drug delivery, I am bemused by the uncritical, almost reverent acceptance by the news media of each new publication on nanomedicine that appears in a decent scientific journal.  A couple of recent examples might include a post on the Economist Babbage site enthusing about peptide-coated nanoworms that are designed to detect elevations of protease activities in certain disease states by releasing the peptides for detection in the urine. Another on the CEN website lauds work using drug bearing polymers to suppress inflammation in CNS microglial cells. This is not to criticize the scientists who did the work or the studies themselves; they are certainly interesting science. However, as is often the case in the nanomedicine area, these very early stage investigations are hailed as breakthroughs that will inevitably result in important advances in clinical medicine. Not likely!

Over the years I have seen hundreds of novel and interesting strategies involving use of nanotechnology for diagnosis or therapy come crashing to a halt as they encounter the complexities of real-world medicine. Yet the breathless, awestruck acceptance of new developments in this field continues. Apparently there is a robust mythology about nanomedicine that is widely accepted. However, a bit more skepticism would probably be good for the field in the long run.