Stories about: sickle cell disease

BCL11A-based gene therapy for sickle cell disease passes key preclinical test

sickle cell gene therapy coming
(unsplash/Pixabay)

Research going back to the 1980s has shown that sickle cell disease is milder in people whose red blood cells carry a fetal form of hemoglobin. The healthy fetal hemoglobin compensates for the mutated “adult” hemoglobin that makes red blood cells stiffen and assume the classic “sickle” shape.

Normally, fetal hemoglobin production tails off after birth, shut down by a gene called BCL11A. In 2008, researchers Stuart Orkin, MD, and Vijay Sankaran, MD, PhD, at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center showed that suppressing BCL11A could restart fetal hemoglobin production; in 2011, using this approach, they corrected sickle cell disease in mice.

Now, the decades-old discovery is finally nearly ready for human testing — in the form of gene therapy. Today in the Journal of Clinical Investigation, Dana-Farber/Boston Children’s researchers report that a precision-engineered gene therapy vector suppressing BCL11A production overcame a key technical hurdle.

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NIH funding snapshots: Your tax dollars at work

2014NIHFundingFunding drives biomedical research, and research drives treatment innovation. Access to funds, particularly National Institute of Health (NIH) awards, is critical to move research forward. The 21st Century Cures Act, which passed the U.S. House on July 10, could give the NIH $8.75 billion more in new grants to disperse over the next five years, the largest increase since the Recovery Act of 2009.

How would those funds be used? Can research find a better way to treat patients? Prevent disease? Disseminate advances in medicine?

In 2014, Boston Children’s led the U.S. in NIH awards. Here’s a look at how a few research teams are leveraging NIH funding to improve care for both children and adults.

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Targeting inflammation in sickle cell disease with fatty acids

sickle cell disease red blood cells
(OpenStax College/Wikimedia Commons)

Painful, tissue-damaging vaso-occlusive crises (a.k.a. pain crises) are one of the key clinical concerns in sickle cell disease (SCD). The characteristic C-shaped red blood cells of SCD become jammed in capillaries, starving tissues of oxygen and triggering searing pain. Over a patient’s life, these repeated rounds of oxygen deprivation (ischemia) can take a heavy toll on multiple organs.

There’s some debate as to why these crises take place—is the sickled cell’s shape and rigidity at fault, or are the blood vessels chronically inflamed and more prone to blockage? Either way, doctors can currently do little to treat vaso-occlusive crises, and nothing to prevent them.

The inflammation view, however, is leading some researchers to ask whether omega-3 fatty acids—which can alleviate inflammation—might be part of the solution. A recent mouse study in the journal Haematologica, led by Mark Puder, MD, PhD, of Boston Children’s Vascular Biology Program, and Carlo Brugnara, MD, of the hospital’s Department of Laboratory Medicine reveals some molecular clues and suggests that human trials of omega-3s might be a good next step.

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Is obesity on the rise among children with sickle cell disease?

Obese child on a scale
Obesity is more common in sickle cell disease than thought. Why?

Ask many doctors about their image of a child with sickle cell disease (SCD), and they’ll describe a short, skinny child, perhaps almost malnourished. For decades, that image was accurate.

That perception needs to change, though. A group of sickle cell specialists from hospitals in New England—members of the 11 institutions in the New England Pediatric Sickle Cell Consortium (NEPSCC)—recently made a surprising observation: Nearly a quarter of children with SCD are overweight or obese. The question is, why?

The answer may start with their red blood cells (RBCs).

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Customized cell therapy for untreatable diseases: Your tax dollars at work

Leonard Zon (top) and Massachusetts Lt. Governor Timothy Murray in the Stem Cell Program's zebrafish facility. (Courtesy MLSC)
Ed. Note: Leonard Zon, MD, is founder and director of the Boston Children’s Hospital Stem Cell Program, which yesterday was awarded $4 million by the Massachusetts Life Sciences Center to build the Children’s Center for Cell Therapy.

As a hematologist, I see all too many children battling blood disorders that are essentially untreatable. Babies with immune deficiencies living life in a virtual bubble, hospitalized again and again for infections their bodies can’t fight. Children disabled by strokes caused by sickle cell disease, or suffering through sickle cell crises that drug treatments can’t completely prevent. Children whose only recourse is to risk a bone marrow transplant—if a suitably matched donor can even be found.

Over the past 20 years, my lab and that of George Daley, MD, PhD, at Boston Children’s Hospital have worked hard to give these children a one-time, potentially curative option—a treatment that begins with patients’ own cells and doesn’t require finding a match.

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There is a cure for sickle cell disease…for some

Maryam Idan (center), a young Iraqi girl with sickle cell disease, was lucky: she could be cured with a stem cell transplant. Leslie Lehmann, MD, wants to make such transplants an option for more sickle cell patients.

I was surprised when chatting recently with Leslie Lehmann, MD, clinical director of the Stem Cell Transplantation Program at Dana-Farber/Children’s Hospital Cancer Center (DF/CHCC). She turned to me and asked, “Did you know there’s been a cure for sickle cell disease for nearly 40 years?”

I had to admit that I didn’t. I’ve always thought of sickle cell—a painful and debilitating disease caused by an inherited mutation that makes red blood cells stiffen into a characteristic sickled shape—as a chronic disease to be managed, not one that could be cured.

I’m not alone in that belief. Lehmann often asks this question when she give talks for medical students, residents and other physicians. Their reaction is puzzlement, then a shaking of heads.

The cure is there, though. It’s a stem cell (aka bone marrow) transplant. The catch is that it’s not available to everyone—but for reasons that Lehmann thinks can be overcome.

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Stopping the pain of sickle cell disease at its source

sickle cell pain
The pain of sickle cell disease can be unbearable. But there’s a new view emerging on how that pain comes about, one that has spurred a new clinical trial aimed at stopping the pain at its source. (stevendepolo/Flickr)

If there’s one thing most patients with sickle cell disease will agree on, it’s that sickle cell hurts. A lot.

The characteristic rigid, sticky, C-shaped red blood cells of this inherited disease tend to get stuck in the small blood vessels of the body. If so many get stuck in a vessel that they cut off blood flow, the body sends out a warning signal in the form of searing pain that doctors call a pain or vaso-occlusive crisis (at least, that’s the historic view; more on that in a minute). The pain can happen anywhere in the body, but most often occurs in the bones of the arms, legs, chest and spine.

Preventing flare-ups—and stopping them when they happen—is a major part of the care plan for any patient with sickle cell. Right now doctors try to avoid pain crises largely by diluting a patient’s blood with fluids or transfusions, thereby keeping the numbers of sickled cells relatively low.

What these treatments don’t do is tackle the pain directly. Doctors can use pain medications, but over time, patients can become tolerant to painkillers, requiring ever-larger doses. What’s needed is something that can stop the complex cascade of events that ignite a pain crisis.

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Getting iron out after putting blood in: Transfusions and iron overload

Frequent transfusions can leave the body overloaded with iron. Ellis Neufeld is helping find new ways of scrubbing that extra iron from the blood. (Research Indicates/Flickr)

In some children the body’s machinery for making red blood cells just doesn’t work right. Conditions like Diamond Blackfan anemia or thalassemia can leave the body anemic, struggling to keep up with its own demands for oxygen. And the misshapen red blood cells of sickle cell disease can get stuck in small blood vessels and cause anemia, organ damage and great pain.

Right now, the most effective way to care for these blood disorders is with blood transfusions. But unlike trauma or surgery, a single transfusion doesn’t solve the problem for people with life-long anemias or sickle cell. Most people with thalassemia, for example, have transfusions every month for their entire life.

“After about 20 transfusions, you reach a point where the body is overloaded with iron from all of the extra hemoglobin that’s been introduced into it,” says Ellis Neufeld, MD, PhD, director of the Thalassemia Program at Dana-Farber/Children’s Hospital Cancer Center (a partnership of Boston Children’s Hospital and Dana-Farber Cancer Institute). “The body has no way to actively remove iron on its own, so the iron starts to build up.” Over time, this can damage the liver, heart, pancreas and other major organs.

Over the last 40 years, a lot of work at DF/CHCC and elsewhere has gone into what’s called chelation therapy: drug-based treatments that scrub the blood of excess iron. Right now there are three chelating drugs in broad use: deferoxamine, deferasirox and deferiprone. They work well for many patients, but have their disadvantages.

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Sickle cell disease and the thalassemias: The advantages of staying forever young

Flipping a single molecular switch could turn off the mutation that causes sickle cell diseae. Stuart Orkin has already done it in mice. (CDC PHIL)

What if we really could turn our bodies’ clocks back? In some cases, that could be a really good thing. Take sickle cell disease. A scourge of tens of thousands worldwide, it stems from a genetic defect in hemoglobin, the oxygen-carrying protein in red blood cells.

Normally, our bodies can produce two forms of hemoglobin: adult hemoglobin, the form susceptible to the sickle cell mutation; and fetal hemoglobin, which is largely produced during development and for a short time after birth. Our bodies finish making the switch from fetal to adult hemoglobin production by about four to six months old – the same time frame when children with the sickle cell mutation first start to show symptoms of the disease.

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Moving gene therapy into high gear

A healthy copy of the affected gene is introduced into the patient's stem cells by means of a vector, a genetically altered virus that does not cause ongoing infection. The stem cells, corrected for the defect, are infused back into the patient. (Click to enlarge.)

Gene therapy, still experimental but beginning to enter the clinic, attempts to utilize advanced molecular methods to treat and even reverse genetic diseases. The field started in earnest about 25 years ago and has had many setbacks along the way to its recent earliest successes.

International collaboration has been critical. Children’s Hospital Boston is one of the founding members of the Transatlantic Gene Therapy Consortium (TAGTC), a new collaboration that seeks to facilitate a more rapid advancement of this technology for treating human diseases. It was initiated shortly after the first trials of gene therapy for X-linked Severe Combined Immunodeficiency (X-SCID) (in both Paris and London) reported leukemia as a serious side effect. The TAGTC was formed to address this setback, developing safer gene therapy reagents, sharing the costs of their development, and then implementing new gene therapy trials for rare diseases across multiple international sites.

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