About this Author
College chemistry, 1983
The 2002 Model
After 10 years of blogging. . .
Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases.
To contact Derek email him directly: firstname.lastname@example.org
July 17, 2014
Here's some big news: Ron Evans and co-workers at Salk report that treatment with the growth factor FGF1 appears to reverse type II diabetes in mice. (Article in Science Daily on this study here). Evans has been working in this field (diabetes, insulin sensitivity, and related areas like growth factors and nuclear receptors) for a long time, and I would definitely take this work seriously.
They reported a couple of years ago that FGF1 seemed to be involved in insulin sensitivity. It's induced in adipose tissue under high-fat diet conditions. FGF1 knockout mice, for their part, have a seemingly normal phenotype, but when they're put on high-fat diets they respond very poorly indeed, quickly showing abnormal glucose control and other defects.
This new paper shows that in normal mice with metabolic problems brought on by a high-fat diet, a single injection of recombinant FGF1 is sufficient to normalize glucose for up to 48 hours. Interestingly (and importantly), this mechanism doesn't seem to overshoot - you don't swing over to hypoglycemia, which is always a worry in this field. And repeated FGF1 therapy leads to increased insulin sensitivity, suppression of hepatic glucose production - basically, everything you'd want in a Type II diabetes therapy. It's great stuff, and the best candidate I've yet seen for the Real Mechanism behind the disease.
Now, FGF1 is a cellular growth factor, so there's a possibility for trouble. But the glucose/insulin effects seem to be mediated by one particular FGF receptor (FGFR1), which makes one hopeful that this axis can be separated out. I would expect to see a great deal of work coming on variants of the protein with longer plasma half-life and greater selectivity. In vivo, the protein seems to be secreted and used locally in specific tissues - it's not in wide circulation. But perhaps it should be - you can be sure that someone's going to try to find out. Overall, this is excellent, exciting news, and we're poised to learn a huge amount about type II diabetes and how to treat it.
+ TrackBacks (0) | Category: Diabetes and Obesity
June 25, 2014
I've written here before about Zafgen, a small startup targeting obesity therapy with an unusual covalent epoxide drug candidate. Last fall they cleared Phase II, and now they're going public.
Bruce Booth, whose firm has been the VC muscle behind the company, has an overview of how things have worked here. It's a good read for anyone interested in where small drug companies come from and what they have to be able to do to be able to survive. Many of the readers here will be familiar with the scientific part of this kind of story (as am I), but the financial and managerial parts have to be handled right, too, and mistakes with any of them can sink the whole effort.
I'll bet that if you'd asked Bruce or his partners back in 2006 for the odds, "Nice big IPO" would have been pretty far down their list of possibilities for the company, even if you'd stipulated success for their drug candidate. MetAP2 (the compound's target, which is something they didn't realize back then) is an interesting enzyme, and obesity has always been an interesting field (although not always in a good way). And on the scientific end, I'm most interested to see how that compound fares as it goes on through Phase III. It's a structure that a lot of us would have crossed off the list about three seconds after seeing it, and anything that extends the bounds of what's feasible in drug discovery is worth keeping an eye on. We very much need for more things to be possible.
+ TrackBacks (0) | Category: Business and Markets | Diabetes and Obesity | Drug Development
June 19, 2014
Yesterday's mention of "nightmare polyphenols" prompted a reader to ask about the one in this paper. That's it over there at the left, and yeah, that sure is a polyphenol. In fact, it's a chaetochromin, a family of mycotoxins originally isolated from moldy rice. The paper doesn't say anything about its stereochemistry, but some can be inferred from their docking models.
Their compound, denoted 4548-G05, does seem to stimulate the insulin receptor, and the list of things that do that is not a long one. A small-molecule IR compound could be quite useful in diabetes patients, of course, but no one's every been able to come up with a plausible drug candidate. Merck made a big splash back in 1999 with another fungal metabolite, L-783,281, but that never became a drug, either. This new paper advances a hypothesis of where the polyphenol binds to the extracellular domain of the insulin receptor and how it might exert its actions.
I would wonder, though, if this compound can't do the same membrane tricks as the other polyphenols mentioned yesterday. The chaetochromins seem to have a number of biological effects, which could be through all sorts of mechanisms. There's nothing to say that some of them aren't due to direct ligand-binding interactions (such as the one proposed in this latest paper), but I wouldn't rule out membrane perturbations, either. And I wouldn't bet on 4058-G05 becoming a drug, although it might lead to one eventually, after a lot of hard work.
+ TrackBacks (0) | Category: Diabetes and Obesity | Natural Products
February 21, 2014
Update: the nomenclature of these enzymes is messy - see the comments.
Here's another activity-based proteomics result that I've been meaning to link to - in this one, the Cravatt group strengthens the case for carboxylesterase 3 as a potential target for metabolic disease. From what I can see, that enzyme was first identified back in about 2004, one of who-knows-how-many others that have similar mechanisms and can hydrolyze who-knows-how-many esters and ester-like substrates. Picking your way through all those things from first principles would be a nightmare - thus the activity-based approach, where you look for interesting phenotypes and work backwards.
In this case, they were measuring adipocyte behavior, specifically differentiation and lipid accumulation. A preliminary screen suggested that there were a lot of serine hydrolase enzymes active in these cells, and a screen with around 150 structurally diverse carbamates gave several showing phenotypic changes. The next step in the process is to figure out what particular enzymes are responsible, which can be done by fluorescence labeling (since the carbamates are making covalent bonds in the enzyme active sites. They found my old friend hormone-sensitive lipase, as well they should, but there was another enzyme that wasn't so easy to identify.
One particular carbamate, the unlovely but useful WWL113, was reasonably selective for the enzyme of interest, which turned out to be the abovementioned carboxyesterase 3 (Ces3). The urea analog (which should be inactive) did indeed show no cellular readouts, and the carbamate itself was checked for other activities (such as whether it was a PPAR ligand). These established a strong connection between the inhibitor, the enzyme, and the phenotypic effects.
With that in hand, they went on to find a nicer-looking compound with even better selectivity, WWL229. (I have to say, going back to my radio-geek days in the 1970s and early 1980s, that I can't see the letters "WWL" without hearing Dixieland jazz, but that's probably not the effect the authors are looking for). Using an alkyne derivative of this compound as a probe, it appeared to label only the esterase of interest across the entire adipocyte proteome. Interestingly, though, it appears that WWL13 was more active in vivo (perhaps due to pharmacokinetic reasons?)
And those in vivo studies in mice showed that Ces3 inhibition had a number of beneficial effects on tissue and blood markers of metabolic syndrome - glucose tolerance, lipid profiles, etc. Histologically, the most striking effect was the clearance of adipose deposits from the liver (a beneficial effect indeed, and one that a number of drug companies are interested in). This recapitulates genetic modification studies in rodents targeting this enzyme, and shows that pharmacological inhibition could do the job. And while I'm willing to bet that the authors would rather have discovered a completely new enzyme target, this is solid work all by itself.
+ TrackBacks (0) | Category: Biological News | Chemical Biology | Diabetes and Obesity
February 7, 2014
Here's something for metabolic disease people to think about: there's a report adding to what we know about the hormone irisin, secreted from muscle tissue, that causes some depots of white adipose tissue to become more like energy-burning brown fat. In the late 1990s, there were efforts all across the drug industry to find beta-3 adrenoceptor agonists to stimulate brown fat for weight loss and dyslipidemia. None of them ever made it through, and thus the arguments about whether they would actually perform as thought were never really settled. One of the points of contention was how much responsive brown adipose tissue adults had available, but I don't recall anything suspecting that it could be induced. In recent years, though, it's become clear that a number of factors can bring on what's been called "beige fat".
Irisin seems to be released in response to exercise, and is just upstream of the important transcriptional regulator PGC-1a. In fact, release of irisin might be the key to a lot of the beneficial effects of exercise, which would be very much worth knowing. In this study, a stabilized version of it, given iv to rodents, had very strong effects on body weight and glucose tolerance, just the sort of thing a lot of people could use.
One of the very interesting features of this area, from a drug discovery standpoint, is that no one has identified the irisin receptor just yet. Look for headlines on that one pretty soon, though - you can bet that a lot of people are chasing it as we speak.
Update: are human missing out on this, compared to mice and other species?
+ TrackBacks (0) | Category: Biological News | Diabetes and Obesity
January 13, 2014
Here's a paper from a few weeks back that I missed during the holidays: work from the Sinclair labs at Harvard showing a new connection between SIRT1 and aging, this time through a mechanism that no one had appreciated. I'll appreciate, in turn, that that opening sentence is likely to divide its readers into those who will read on and those who will see the words "SIRT1" or "Sinclair" and immediate seek their entertainment elsewhere. I feel for you, but this does look like an interesting paper, and it'll be worthwhile to see what comes of it.
Here's the Harvard press release, which is fairly detailed, in case you don't have access to Cell. The mechanism they're proposing is that as NAD+ levels decline with age, this affects SIRT1 function to the point that it no longer constains HIF-1. Higher levels of HIF-1, in turn, disrupt pathways between the nucleus and the mitochondia, leading to lower levels of mitochondria-derived proteins, impaired energy generation, and cellular signs of aging.
Very interestingly, these effects were reversed (on a cellular/biomarker level) by one-week treatment of aging mice with NMN (nicotine mononucleotide edit: fixed typo), a precursor to NAD. That's kind of a brute-force approach to the problem, but a team from Washington U. recently showed extremely similar effects in aging diabetic rodents supplemented with NMN, done for exactly the same NAD-deficiency reasons. I would guess that the NMN is flying off the shelves down at the supplement stores, although personally I'll wait for some more in vivo work before I start taking it with my orange juice in the mornings.
Now, whatever you think of sirtuins (and of Sinclair's work with them), this work is definitely not crazy talk. Mitochondria function has long been a good place to look for cellular-level aging, and HIF-1 is an interesting connection as well. As many readers will know, that acronym stands for "hypoxia inducible factor" - the protein was originally seen to be upregulated when cells were put under low-oxygen stress. It's a key regulatory switch for a number of metabolic pathways under those conditions, but there's no obvious reason for it to be getting more active just because you're getting older. Some readers may have encountered it as an oncology target - there are a number of tumors that show abnormal HIF activity. That makes sense, on two levels - the interiors of solid tumors are notoriously oxygen-poor, so that would at least be understandable, but switching on HIF under normal conditions is also bad news. It promotes glycolysis as a metabolic pathway, and stimulates growth factors for angiogenesis. Both of those are fine responses for a normal cell that needs more oxygen, but they're also the behavior of a cancer cell showing unrestrained growth. (And those cells have their tradeoffs, too, such as a possible switch between metastasis and angiogenesis, which might also have a role for HIF).
There's long been speculation about a tradeoff between aging and cellular prevention of carcinogenicity. In this case, though, we might have a mechanism where our interests on on the same side: overactive HIF (under non-hypoxic conditions) might be a feature of both cancer cells and "normally" aging ones. I put that word in quotes because (as an arrogant upstart human) I'm not yet prepared to grant that the processes of aging that we undergo are the ones that we have to undergo. My guess is that there's been very little selection pressure on lifespan, and that what we've been dealt is the usual evolutionary hand of cards: it's a system that works well enough to perpetuate the species and beyond that who cares?
Well, we care. Biochemistry is a wonderful, heartbreakingly intricate system whose details we've nowhere near unraveled, and we often mess it up when we try to do anything to it, anyway. But part of what makes us human is the desire (and now the ability) to mess around with things like this when we think we can benefit. Not looking at the mechanisms of aging seems to me like not looking at the mechanisms of, say, diabetes, or like letting yourself die of a bacterial infection when you could take an antibiotic. Just how arrogant that attitude is, I'm not sure yet. I think we'll eventually get the chance to find out. All this recent NAD work suggests that we might get that chance sooner than later. Me, I'm 51. Speed the plow.
+ TrackBacks (0) | Category: Aging and Lifespan | Biological News | Diabetes and Obesity
December 19, 2013
As the Wall Street Journal reported last night, Bristol-Myers Squibb is getting out of the diabetes business entirely, selling its collaboration with AstraZeneca back to AZ.
As part of the transaction, and subject to local consultation and legislation, Bristol-Myers Squibb and AstraZeneca anticipate that substantially all employees of Bristol-Myers Squibb dedicated to the diabetes business will be transferred to AstraZeneca. A number of R&D and manufacturing employees dedicated to diabetes will remain with Bristol-Myers Squibb to progress the diabetes portfolio and support the transition for these areas. Bristol-Myers Squibb will work closely with AstraZeneca to ensure a smooth transition.
What happens once that diabetes portfolio is "progressed"? I haven't heard details yet, and they may not even be available. Given the recent moves by BMS, though, this announcement shouldn't come as a huge surprise. It does say some interesting things about the positions of the two companies. BMS sees big opportunities in its oncology portfolio, and by comparison, the diabetes business looks slow-moving and too expensive for the return it offers. AstraZeneca, by contrast, needs all the help it can get. Actual drugs that are bringing in actual money, and whose patents are not expiring next Tuesday? Not bad.
+ TrackBacks (0) | Category: Business and Markets | Diabetes and Obesity
November 15, 2013
I wrote here about Zafgen and their covalent Met-Ap2 inhibitor beloranib. Word is out today that the compound has passed its first Phase II trial handily, so score one for covalent epoxides as drug candidates.
Zafgen has followed up promising results from early-stage work on its weight drug beloranib with a stellar Phase II study that tracked rapid weight loss among the severely obese, with one group shedding an average of 22 pounds in 12 weeks. CEO Tom Hughes says the mid-stage success clears a path to a Phase IIb trial that can fine tune the dose while taking more time to gauge the longterm impact of its treatment on weight. And the data harvest sets the right tone for ongoing talks with investors about a new financing round for the biotech.
Efficacy, though, doesn't seem to have been in much doubt with this compound. Phase III will be the big one, because the worry here will be some sort of funny longer-term toxicity. No one's quite sure what inhibiting that enzyme will do (other than this pretty impressive weight loss), and a covalent drug (even a relatively benign and selective one like an epoxide) is always going to have questions around it until it's proven itself in human tox. But so far, so good.
One thing that beloranib has going for it is that patients would presumably take for a relatively limited course of therapy and then try to keep the weight off on their own. That's a big distinction, toxicologically. On one end of the spectrum, you've got your one-time-use drugs, like an anesthetic, and then there are the anti-infectives that you might take for two weeks or (at most) a few months. But at the other end, you have the cardiovascular and diabetes drugs that your patient population is going to be taking every morning for the rest of their lives, and the safety profile is clearly going to have to clearer in those cases.
Critics of the industry never fail to mention that we, supposedly, are not looking for cures, but rather for drugs in that latter category so we can reap the big, big profits. They haven't thought this through well enough: for one thing, a cure is worth more money up front. And there is that tiny little factor of patent lifetime. To hear some people talk, you'd think that a drug's discoverers continue to reap the gains forever, but it ain't so. Ask Eli Lilly right now how that's going - most of their revenue is in the process of packing up and leaving for the generics companies. It doesn't matter if a company finds a drug that people need to take for fifty years; they're not going to be selling it that long.
Back to Zafgen, though. They've got an interesting program going here, and I'm very curious to see how it works out. Going after obesity from the metabolic end is something that a lot of people have tried, through various mechanisms, but it's still probably a better bet than trying to affect appetite. And I'll be glad to see an epoxide-based drug prove itself in the clinic, because I think that evidence suggests that they're better drug candidates than we give them credit for (see the link in the first line of this post for more on that). We medicinal chemists need all the options we can get. From the way things look, I'd bet on beloranib going fine through the rest of Phase II - and then begins the finger-crossing and rabbit's-footing.
+ TrackBacks (0) | Category: Clinical Trials | Diabetes and Obesity
November 8, 2013
So Bristol-Myers Squibb did indeed re-org itself yesterday, with the loss of about 75 jobs (and the shifting around of 300 more, which will probably result in some job losses as well, since not everyone is going to be able to do that). And they announced that they're getting out of two therapeutic areas, diabetes and neuroscience.
Those would be for very different reasons. Neuro is famously difficult and specialized. There are huge opportunities there, but they're opportunities because no one's been able to do much with them, for a lot of good reasons. Some of the biggest tar pits of drug discovery are to be found there (Alzheimer's, chronic pain), and even the diseases for which we have some treatments are near-total black boxes, mechanistically (schizophrenia, epilepsy and seizures). The animal models are mysterious and often misleading, and the clinical trials for the biggest diseases in this area are well-known to be expensive and tricky to run. You've got your work cut out for you over here.
Meanwhile, the field of diabetes and metabolic disorders is better served. For type I diabetes, the main thing you can do, short of finding ever more precise ways of dosing insulin, is to figure out how to restore islet function and cure it, and that's where all the effort seems to be going. For type II diabetes, which is unfortunately a large market and getting larger all the time, there are a number of therapeutic options. And while there's probably room for still more, the field is getting undeniably a bit crowded. Add that to the very stringent cardiovascular safety requirements, and you're looking at a therapeutic that's not as attractive for new drug development as it was ten or fifteen years ago.
So I can see why a company would get out of these two areas, although it's also easy to think that it's a shame for this to happen. Neuroscience is in a particularly tough spot. The combination of uncertainly and big opportunities would tend to draw a lot of risk-taking startups to the area, but the massive clinical trials needed make it nearly impossible for a small company to get serious traction. So what we've been seeing are startups that, even more than other areas, are focused on getting to the point that a larger company will step in to pay the bills. That's not an abnormal business model, but it has its hazards, chief among them the temptation to run what trials you can with a primary goal of getting shiny numbers (and shiny funding) rather than finding out whether the drug has a more solid chance of working. Semi-delusional Phase II trials are a problem throughout the industry, but more so here.
+ TrackBacks (0) | Category: Business and Markets | Diabetes and Obesity | Drug Development | The Central Nervous System
August 15, 2013
I haven't written much about Mannkind recently. This has been a long, long, expensive saga to develop an inhaled-insulin delivery system (Afrezza), which is an idea that all by itself has seems to have swallowed several billion dollars and never given anything back yet. (That link above will send you to some of the story, and this one will tell you something about the disastrous failure of the only inhaled insulin to reach the market so far).
In 2011, Mannkind looked as if they were circling the drain. But (as has been the case many times before), more money was heaved into what might still turn out to be an incinerator, and they kept going. Just in the last few days, they've released another batch of Phase III data, which looked positive. You can see from the year-to-date stock chart that people have been anticipating this, which might account for the way that MNKD hasn't exactly taken off on the news. The stocked jumped at the open yesterday, then spent the rest of the day wandering down, and opened today right back where it was before the news came out.
People might be worried about possible effects on lung function, which show up in the data (FEV1 as well as a side effect of coughing). But there are potentially even bigger concerns in the number for HbA1c and fasting glucose. A closer look at the data shows that Mannkind's product may not have clearly established itself versus the injected-insulin competition. As that FiercePharma story says, this might not keep the product from being approved, but it could give it a rough time in the marketplace (and give Mannkind a rough time finding a big partner).
I wonder if there are any investors - other than Al Mann - who have stuck with this company all the way? If so, I wonder what effect that's had on their well-being? It has been a long, bizarre ride, and no one knows how many more curves and washed-out bridges might still be out there.
+ TrackBacks (0) | Category: Clinical Trials | Diabetes and Obesity
July 11, 2013
Roche has announced that they're halting trials of aleglitazar, a long-running investigational drug in their diabetes portfolio. I'm noting this because I think that this might be the absolute last of the PPAR ligands to fail in the clinic. And boy howdy, has it been a long list. Merck, Lilly, Kyorin, Bristol-Myers Squibb, Novo Nordisk, GlaxoSmithKline, and Bayer are just the companies I know right off the top of my head that have had clinical failures in this area, and I'm sure that there are plenty more. Some of those companies (GSK, for sure) have had multiple clinical candidates go down, so the damage is even worse than it appears.
That why I nominated this class in the Clinical Futility Awards earlier this summer. Three PPAR compounds actually made it to market, but the record has not been happy there, either. Troglitazone was pulled early, Avandia (rosiglitazone) has (after a strong start) been famously troubled, and Actos (pioglitazone) has its problems, too.
The thing is, no one knows about all this, unless they follow biomedical research in some