From the category archives:

Drug discovery

In this screengrab from a Nature video, a siRNA, cradled by an argonaute protein, binds to a messenger RNA. (Watch the full video at: https://www.youtube.com/watch?v=cK-OGB1_ELE)

In this screen grab from a Nature video, a siRNA, cradled by an argonaute protein, binds to a messenger RNA. (More at www.youtube.com/watch?v=cK-OGB1_ELE)

RNA interference (RNAi) is a therapeutic technology that blocks gene expression with either small interfering RNAs (siRNA) or microRNAs (miRNA). RNAi’s discovery was considered transformative enough to earn the 2006 Nobel Prize for Physiology or Medicine, but from the start the challenge of delivering RNA-silencing therapeutics to the right tissues has hobbled efforts to use RNAi to treat patients.

Citing this challenge, the pharmaceutical giant Novartis is the latest major company to withdraw from RNAi research, following Merck and Roche. Forbes was prompted to write:

…for certain diseases where an RNAi therapeutant can be more readily introduced, such as the eye, or ‘privileged compartments’ such as the liver, RNAi still has potential. But given that these therapies would be expensive due to the high cost-of-goods involved in synthesizing these agents, they would have to be targeted to diseases where the cost of therapy would be justified by the beneficial medical effects. … to say that RNAi therapy will rival monoclonal antibodies in terms of revenue potential—well, that’s a bit of a stretch.

Barry Greene, COO of Alnylam Pharmaceuticals, a biotech that’s championed RNAi, countered in Fierce Drug Delivery: “Novartis pulling out is an exemplar of Big Pharma not being able to innovate, and historically they have never been able to innovate.” Full story »

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Daniel Kohane of Boston Children's Hospital is developing drug delivery technologies that rely on nanoparticles and the spectrum of light.Getting drugs where they need to be, and at the right time, can be more challenging than you think. Tumors, for example, tend to have blood vessels that are tighter and twistier than normal ones, making it hard for drugs to penetrate them. Despite decades of research on antibodies, peptides and other guidance methods, drug makers struggle to target drugs to specific tissues or cell types.

And even once a drug arrives at the right place, the ability to fine-tune the dose so that the drug is released at the right time and in the right amount remains an elusive goal.

What’s needed is some kind of trigger, a stimulus that a clinician can turn on and off to guide when a drug is available and where it goes to make sure it does its job with the fewest side effects.

Daniel Kohane, MD, PhD, a critical care specialist and director of the Laboratory for Biomaterials and Drug Delivery at Boston Children’s Hospital, thinks he’s hit upon a promising trigger, one that’s all around us: light. Full story »

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Alprolix FDA approval recombinant factor IX rFIXFc hemophilia B coagulation

(Courtesy Biogen Idec)

A few weeks ago Vector brought you the backstory of how a clotting factor for hemophilia was made to last longer in the blood, allowing injections to be pared to once every week or two, rather than two to three per week.

Today we bring more good news: Following a successful Phase III trial, rFIXFc recently received the green light for marketing from the FDA and from Health Canada.

Developed by Biogen Idec under the trade name Alprolix™, rFIXFc—a modified version of clotting factor IX—is the fruition of a technology first envisioned by three researchers—gastroenterologists Wayne Lencer, MD, of Boston Children’s Hospital, and Richard Blumberg, MD, of Brigham and Women’s Hospital, and immunologist Neil Simister, DPhil, of Brandeis University—for large protein drugs. Their idea: to extend the drugs’ half-lives by protecting them from being ground up by cells. Full story »

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Group handshake representing a consortiumDavid Altman is manager of marketing and communications in Boston Children’s Hospital’s Technology and Innovation Development Office.

Successful therapeutic development requires multiple stakeholders along the path from discovery to translation to clinical trials to FDA approval to market availability. At various points along this path, academia, industry, government, hospitals, nonprofits and philanthropists may work together. Would bringing these stakeholders together from start to finish lead to greater success?

A growing number of private-public consortia are launching in defined “pre-competitive” spaces where potential rivals collaborate to generate tools and data to accelerate biomedical research. In 1995, consortia were rare in health care: Only one was created. In 2012, 51 new consortia were launched, according to the organization Faster Cures.

Why? you may ask. Banding together in consortia can reduce costs, minimize failures and shorten the timeline to approval for new drugs. Full story »

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Meat grinder protecting protein drugs from being ground up by cells clotting factors

Cells can grind up large protein drugs. A new technology may help those drugs escape and stay in the bloodstream longer.

Getting drugs to stay in the bloodstream longer is a big deal when it comes to treating chronic diseases. You see, a drug’s half-life—the time it takes for half of a given dose to be cleared from the body—determines how long its effect(s) last.

If a drug’s half-life is short—meaning it’s cleared quickly—patients will have to take the drug frequently. Given that someone with a chronic condition could be on the medication for many years—say, patients with severe hemophilia, who endure frequent infusions of clotting factors—a short half-life can translate into high cost. Depending on side effects and how the drug is administered, quality of life may also suffer.

Several years ago, Wayne Lencer, MD, a researcher in Boston Children’s Hospital’s Division of Gastroenterology, Hepatology and Nutrition, and his collaborators Richard Blumberg, MD, at Brigham and Women’s Hospital (BWH) and Neil Simister, DPhil, at Brandeis University came up with a way to make protein-based drugs like clotting factors stay in the circulation longer: by keeping cells from grinding them up.

The first drug based on their work—a form of the factor IX clotting factor—just passed a Phase III clinical trial reported in The New England Journal of Medicine. Full story »

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Did arbaclofen really fail in autism and fragile X?

Did arbaclofen really fail in autism and fragile X?

Walter Kaufmann, MD, is co-director of the Fragile X Syndrome Program and a member of the department of Neurology at Boston Children’s Hospital. He was site principal investigator for three arbaclofen trials sponsored by Seaside Therapeutics and currently advises the company on data analyses. This post is second in a two-part series on clinical trials in autism spectrum disorders. (Read part 1)

The outcomes of drug trials in autism spectrum disorder (ASD) have, to date, been mixed. While atypical neuroleptic drugs have been effective for treating disruptive behavior in people with autism and are FDA-approved for that purpose, no available psychotropic drug has improved the core symptoms of ASD, such as social interaction deficits or stereotypic behaviors.

The heterogeneity—diversity—of ASD in both causes and symptoms may explain treatment failures to some extent. However, we have also lacked drugs targeting the brain mechanisms that underlie ASD. For this reason, targeted trials in fragile X syndrome, informed by neurobiology, have raised hopes of finally addressing core autistic symptoms.

Fragile X syndrome is a genetic disorder in which ASD occurs in 15 to 40 percent of cases. Initial results from a Phase 2 trial using the GABA-B agonist arbaclofen demonstrated relatively selective improvements in social avoidance in a wide age-range sample of subjects. Full story »

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nanomedicineGood things, including therapeutics, can come in small packages—and increasingly this means nano-sized packages. For a sense of the scale of these diminutive tools, a strand of human DNA is 2.5 nanometers in diameter.

Nanomedicine offers the promise of drugs that are activated by physiologic stimuli in the body (like the shear stress of blood flow that’s partially blocked by a clot), that can home to very specific targets in the body (like pancreatic islets that are being attacked by the immune system in diabetes) and that carry their own imaging agents—a built-in “metric” to show that they’re working. Biomaterials are being crafted to enhance their properties—like adding gold “nanowires” to heart patches to increase their electrical conductivity.

Vector’s new sister publication, Innovation Insider, looks at the promise and challenges of nanomedicine—both technical and regulatory. Read more about nanoscissors, theranostics, quantum dots and how the future is nano.

If you’d like to receive Innovation Insider in your inbox, sign up here.

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Using a novel 3-D culture method, scientists were able to prod lung (bronchioalveolar) stem cells to produce colonies containing the cell type of choice: airway (bronchiolar) epithelial cells, alveolar epithelial cells or both. (Images: Joo-Hyeon Lee)

Using a novel 3-D culture method, scientists were able to prod lung (bronchioalveolar) stem cells to produce colonies with the cell type of choice: airway (bronchiolar) epithelial cells, alveolar epithelial cells or both. (Images: Joo-Hyeon Lee)

Someday it may be possible to treat lung diseases like emphysema, pulmonary fibrosis or asthma by prodding the lungs to produce healthy versions of the cells that are damaged.

That’s the hope of researchers Carla Kim, PhD, and Joo-Hyeon Lee, PhD, of the Stem Cell Research Program at Boston Children’s Hospital. In the Jan. 30 issue of Cell, they describe a pathway in the lungs, activated by injury, that directs stem cells to transform into specific kinds of cells—and that can be manipulated to enhance different kinds of repair, at least in a mouse model.

By boosting the pathway, Kim, Lee and colleagues successfully increased production of alveolar epithelial cells, which line the lung’s alveoli—the tiny sacs where gas exchange takes place, and that are irreversibly damaged in diseases like pulmonary fibrosis and emphysema. Full story »

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The footpads of diabetic mice (line-D) treated with a cream containing XIB4035 have increased numbers of nerve terminals (shown in green in the lower right panel), whereas mice given a control cream (lower left) do not. The top two panels represent healthy “wild type” mice.

The footpads of diabetic mice given a cream containing XIB4035 (lower right) have new nerve terminals (shown in green), whereas mice given a control cream (lower left) do not. The top two panels represent healthy “wild type” mice.

About half of people with diabetes develop peripheral neuropathy. The most common form, small-fiber neuropathy, generally starts in the feet, causing pain, odd sensations like pricks and “pins and needles,” and—the most worrisome feature—a loss of sensation that can increase the chance of ulcers and infections.

In some cases, that may lead to the need for amputation—as happened with my diabetic great-grandfather whose numbed feet, unbeknownst to him, got too close to the fire.

While there are some treatments to reduce pain, there’s nothing that restores sensation. Nor do any existing treatments address the underlying cause of the neuropathy: the degeneration or dysfunction of the endings of the sensory neurons in the skin. Full story »

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A zebrafish model of leukemia has helped find that an antipsychotic drug has anticancer properties.One of the hot trends in drug discovery could be called drug re-discovery: finding new uses for drugs that have already received FDA approval for a different indication.

It’s an approach that allows researchers and clinicians to rapidly test potential treatments for rare or difficult-to-treat conditions. Because the drug’s safety profile is already known, much of the preclinical and early clinical work that goes into developing a drug can be bypassed.

It was this kind of strategy that Alejandro Gutierrez, MD, and A. Thomas Look, MD, of Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, and Jon Aster, MD, PhD, of Dana-Farber Cancer Institute and Brigham and Women’s Hospital, had in mind when they started screening a library of nearly 5,000 FDA-approved compounds, off-patent drugs and natural products using a zebrafish model of T-cell acute lymphoblastic leukemia (T-ALL).

And with that strategy, they may have struck gold. Just not in the way they had expected. Full story »

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