Moore’s Law: number of semiconductors on a chip doubling every 18 months or so, etc. Everyone’s heard of it. But can we agree that anyone who uses it as a metaphor or perscription for drug research doesn’t know what they’re talking about?
I first came across the comparison back during the genomics frenzy. One company that had bought into the craze in a big way press-released (after a rather interval) that they’d advanced their first compound to the clinic based on this wonderful genomics information. I remember rolling my eyes and thinking “Oh, yeah”, but on a hunch I went to the Yahoo! stock message boards (often a teeming heap of crazy, then as now). And there I found people just levitating with delight at this news. “This is Moore’s Law as applied to drug discovery!” shouted one enthusiast. “Do you people realize what this means?” What it meant, apparently, was not only that this announcement had come rather quickly. It also meant that this genomics stuff was going to discover twice as many drugs as this real soon. And real soon after that, twice as many more, and so on until the guy posting the comment was as rich as Warren Buffet, because he was a visionary who’d been smart enough to load himself into the catapult and help cut the rope. (For those who don’t know how that story ended, the answer is Not Well: the stock that occasioned all this hyperventilation ended up dropping by a factor of nearly a hundred over the next couple of years. The press-released clinical candidate was never, ever, heard of again).
I bring this up because a reader in the industry forwarded me this column from Bio-IT World, entitled, yes, “Only Moore’s Law Can Save Big Pharma”. I’ve read it three times now, and I still have only the vaguest idea of what it’s talking about. Let’s see if any of you can do better.
The author starts off by talking about the pressures that the drug industry is under, and I have no problem with him there. That is, until he gets to the scientific pressures, which he sketches out thusly:
Scientifically, the classic drug discovery paradigm has reached the end of its long road. Penicillin, stumbled on by accident, was a bona fide magic bullet. The industry has since been organized to conduct programs of discovery, not design. The most that can be said for modern pharmaceutical research, with its hundreds of thousands of candidate molecules being shoveled through high-throughput screening, is that it is an organized accident. This approach is perhaps best characterized by the Chief Scientific Officer of a prominent biotech company who recently said, “Drug discovery is all about passion and faith. It has nothing to do with analytics.”
The problem with faith-based drug discovery is that the low hanging fruit has already been plucked, driving would be discoverers further afield. Searching for the next miracle drug in some witch doctor’s jungle brew is not science. It’s desperation.
The only way to escape this downward spiral is new science. Fortunately, the fuzzy outlines of a revolution are just emerging. For lack of a better word, call it Digital Chemistry.
And when the man says “fuzzy outline”, well, you’d better take him at his word. What, I know you’re all asking, is this Digital Chemistry stuff? Here, wade into this:
Tomorrow’s drug companies will build rationally engineered multi-component molecular machines, not small molecule drugs isolated from tree bark or bread mold. These molecular machines will be assembled from discrete interchangeable modules designed using hierarchical simulation tools that resemble the tool chains used to build complex integrated circuits from simple nanoscale components. Guess-and-check wet chemistry can’t scale. Hit or miss discovery lacks cross-product synergy. Digital Chemistry will change that.
Honestly, if I start talking like this, I hope that onlookers will forgo taking notes and catch on quickly enough to call the ambulance. I know that I’m quoting too much, but I have to tell you more about how all this is going to work:
But modeling protein-protein interaction is computationally intractable, you say? True. But the kinetic behavior of the component molecules that will one day constitute the expanding design library for Digital Chemistry will be synthetically constrained. This will allow engineers to deliver ever more complex functional behavior as the drugs and the tools used to design them co-evolve.
How will drugs of the future function? Intracellular microtherapeutic action will be triggered if and only if precisely targeted DNA or RNA pathologies are detected within individual sick cells. Normal cells will be unaffected. Corrective action shutting down only malfunctioning cells will have the potential of delivering 99% cure rates. Some therapies will be broad based and others will be personalized, programmed using DNA from the patient’s own tumor that has been extracted, sequenced, and used to configure “target codes” that can be custom loaded into the detection module of these molecular machines.
Look, I know where this is coming from. And I freely admit that I hope that, eventually, a really detailed molecular-level knowledge of disease pathology, coupled with a really robust nanotechnology, will allow us to treat disease in ways that we can’t even approach now. Speed the day! But the day is not sped by acting as if this is the short-term solution for the ills of the drug industry, or by talking as if we already have any idea at all about how to go about these things. We don’t.
And what does that paragraph up there mean? “The kinetic behavior. . .will be synthetically constrained”? Honestly, I should be qualified to make sense of that, but I can’t. And how do we go from protein-protein interactions at the beginning of all that to DNA and RNA pathologies at the end, anyway? If all the genomics business has taught us anything, it’s that these are two very, very different worlds – both important, but separated by a rather wide zone of very lightly-filled-in knowledge.
Let’s take this step by step; there’s no other way. In the future, according to this piece, we will detect pathologies by detecting cell-by-cell variations in DNA and/or RNA. How will we do that? At present, you have to rip open cells and kill them to sequence their nucleic acids, and the sensitivities are not good enough to do it one cell at a time. So we’re going to find some way to do that in a specific non-lethal way, either from the outside of the cells (by a technology that we cannot even yet envision) or by getting inside them (by a technology that we cannot even envision) and reading off their sequences in situ (by a technology that we cannot even envision). Moreover, we’re going to do that not only with the permanent DNA, but with the various transiently expressed RNA species, which are localized to all sort of different cell compartments, present in minute amounts and often for short periods of time, and handled in ways that we’re only beginning to grasp and for purposes that are not at all yet clear. Right.
Then. . .then we’re going to take “corrective action”. By this I presume that we’re either going to selectively kill those cells or alter them through gene therapy. I should note that gene therapy, though incredibly promising as ever, is something that so far we have been unable, in most cases, to get to work. Never mind. We’re going to do this cell by cell, selectively picking out just the ones we want out of the trillions of possibilities in the living organism, using technologies that, I cannot emphasize enough, we do not yet have. We do not yet know how to find most individual cells types in a complex living tissue; huge arguments ensue about whether certain rare types (such as stem cells) are present at all. We cannot find and pick out, for example, every precancerous cell in a given volume of tissue, not even by slicing pieces out of it, taking it out into the lab, and using all the modern techniques of instrumental analysis and molecular biology.
What will we use to do any of this inside the living organism? What will such things be made of? How will you dose them, whatever they are? Will they be taken up though the gut? Doesn’t seem likely, given the size and complexity we’re talking about. So, intravenous then, fine – how will they distribute through the body? Everything spreads out a bit differently, you know. How do you keep them from sticking to all kinds of proteins and surfaces that you’re not interested in? How long will they last in vivo? How will you keep them from being cleared out by the liver, or from setting off a potentially deadly immune response? All of these could vary from patient to patient, just to make things more interesting. How will we get any of these things into cells, when we only roughly understand the dozens of different transport mechanisms involved? And how will we keep the cells from pumping them right back out? They do that, you know. And when it’s time to kill the cells, how do you make absolutely sure that you’re only killing the ones you want? And when it’s time to do the gene therapy, what’s the energy source for all the chemistry involved, as we cut out some sequences and splice in the others? Are we absolutely sure that we’re only doing that in just the right places in just the right cells, or will we (disastrously) be sticking in copies into the DNA of a quarter of a per cent of all the others?
And what does all this nucleic acid focus have to do with protein expression and processing? You can’t fix a lot of things at the DNA level. Misfolding, misglycosylation, defects in transport and removal – a lot of this stuff is post-genomic. Are we going to be able to sequence proteins in vivo, cell by cell, as well? Detect tertiary structure problems? How? And fix them, how?
Alright, you get the idea. The thing is, and this may be surprising considering those last few paragraphs, that I don’t consider all of this to be intrinsically impossible. Many people who beat up on nanotechnology would disagree, but I think that some of these things are, at least in broad hazy theory, possibly doable. But they will require technologies that we are nowhere close to owning. Babbling, as the Bio-IT World piece does, about “detection modules” and “target codes” and “corrective action” is absolutely no help at all. Every one of those phrases unpacks into a gigantic tangle of incredibly complex details and total unknowns. I’m not ready to rule some of this stuff out. But I’m not ready to rule it in just by waving my hands.