Stories about: Dana-Farber Boston Children’s

Blood stem cell transplants from any donor, without toxicity?

could stem cell transplants be made nontoxic?
(ADOBE STOCK)

Many blood disorders, immune disorders and metabolic disorders can be cured with a transplant of hematopoietic (blood-forming) stem cells, also known as bone marrow transplant. But patients must first receive high-dose, whole-body chemotherapy and/or radiation to deplete their own defective stem cells, providing space for the donor cells to engraft. These “conditioning” regimens are highly toxic: they wipe out the immune system, raising infection risk, and can cause anemia, infertility, other organ damage and cancers. And when the donor isn’t an exact match, patients’ immune systems must be suppressed for prolonged periods to prevent rejection.

As a result, most patients either don’t receive a transplant or must endure serious side effects. But if two new studies bear out in clinical trials, a far gentler conditioning treatment could enable stem-cell transplants for a much wider range of disorders, even possibly from unmatched donors.

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Overriding resistance to epigenetic inhibitors in neuroblastoma: Targeting PI3K

(IMAGE COURTESY NATIONAL CANCER INSTITUTE)

Children’s cancers pose unique challenges. They’re not caused by the same kinds of genetic mutations that cause adult cancers, and only a minority of their mutations can be targeted with drugs. In a recent study, Kimberly Stegmaier, MD, at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and her colleagues systematically deleted every gene in the genome in a number of childhood cancers. This led them to previously unknown — and targetable — genes that help drive tumor growth.

But Stegmaier is also interested in epigenetic regulators — proteins that help control the regulation of genes and contribute to many pediatric cancers. They’re a hot subject of research: Child cancers tend to arise in developing tissues, and epigenetic regulators are active during early development. Clinical trials are starting to test drugs that inhibit epigenetic cancer-promoting factors.

There’s a problem, though: Cancers often become resistant to targeted inhibitors, including epigenetic inhibitors. So, again using genome-wide approaches, Stegmaier set out to find ways to overcome this resistance.

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CRISPR-Cas9 screen opens new targets for Ewing sarcoma, other childhood cancers

Ewing sarcoma research by Kimberly Stegmaier, MD
The TP53 pathway normally helps pull the plug on cancerous cells. While the pathway is intact in most pediatric cancers, research finds that drugs targeting the pathway can curb tumor cell proliferation in Ewing sarcoma. Photo: Kimberly Stegmaier, MD (SAM OGDEN / DANA-FARBER CANCER INSTITUTE)

While the genetic mutations driving adult cancers can sometimes be targeted with drugs, most pediatric cancers lack good targets. That’s because their driving genetic alterations often create fusion proteins that aren’t easy for drugs to attack.

“This is one reason why it is notoriously hard to make targeted drugs against childhood cancers — their cancer-promoting proteins often lack good pockets for drugs to bind to,” says Kimberly Stegmaier, MD.

However, that’s beginning to change.

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After 80 years, genetic causes of Diamond-Blackfan anemia come into view

Vijay Sankaran, MD and a patient with Diamond-Blackfan anemia
Hematologist Vijay Sankaran with Jack Farwell (PHOTO: MICHAEL GODERRE / BOSTON CHILDREN’S HOSPITAL)

In 1938, Louis K. Diamond, MD, and Kenneth Blackfan, MD, at Boston Children’s Hospital described a severe congenital anemia that they termed “hypoplastic” (literally, “underdeveloped”) because of the bone marrow’s inability to produce mature, functioning red blood cells. Eighty years later, the multiple genetic origins of this highly rare disease, now known as Diamond-Blackfan anemia, or DBA, are finally coming into view.

The largest study to date, published recently in the American Journal of Human Genetics, raises as many questions as it answers. But in the meantime, it provides a genetic explanation for nearly 80 percent of patients.

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ctDNA: Bringing ‘liquid biopsies’ to pediatric solid tumors

Brian Crompton studies the use of ctDNA as an alternative way to biopsy pediatric solid tumors
Brian Crompton with Stephanie Meyer (left) and Kellsey Wuerthele (PHOTO: JOHN DEPUTY)

Our blood carries tiny amounts of DNA from broken-up cells. If we have cancer, some of that DNA comes from tumor cells. Studies performed with adult cancers have shown that this circulating tumor DNA (ctDNA) may offer crucial clues about tumor genetic mutations and how tumors respond to treatment.

Brian Crompton, MD, with colleagues at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and elsewhere, is now working to bring ctDNA “liquid biopsies” to pediatric solid tumors as well. The researchers hope that these blood tests will eventually improve early detection, choice of treatment and monitoring of young patients with these diseases without having to sample the tumor itself.

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In zebrafish, a way to find new cancer therapies, targeting tumor promoters

A new study suggests the power of zebrafish as tools for cancer drug discovery (PHOTO: KATHERINE C. COHEN)

The lab of Leonard Zon, MD, has long been interested in making blood stem cells in quantity for therapeutic purposes. To test for their presence in zebrafish, their go-to research model, they turned to the MYB gene, a marker of blood stem cells. To spot the cells, Joseph Mandelbaum, a PhD candidate in the lab, attached a fluorescent green tag to MYB that made it easily visible in transparent zebrafish embryos.

“It was a real workhorse line for us,” says Zon, who directs the Stem Cell Research Program at Boston Children’s Hospital.

In addition to being a marker of blood stem cells, MYB is an oncogene. About five years ago, Zon was having lunch at a cancer meeting and, serendipitously, sat next to Jeff Kaufman, who was also interested in MYB. Kaufman was excited to hear about Zon’s fluorescing MYB zebrafish, which can be studied at scale and are surprisingly similar to humans genetically.

“Have you ever heard of adenoid cystic carcinoma?” he asked Zon.

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Putting patients first in the translational research pipeline

During a follow-up visit, pediatric hematologist/oncologist Sung-Yun Pai, MD, hugs a patient who received gene therapy for X-linked severe combined immunodeficiency.
During a follow-up visit at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, pediatric hematologist/oncologist Sung-Yun Pai, MD, hugs a patient who received gene therapy for X-linked severe combined immunodeficiency.

This is part II of a two-part blog series recapping the 2018 BIO International Convention. Read part I: Forecasting the convergence of artificial intelligence and precision medicine.

The hope to improve people’s lives is what drives many members of industry and academia to bring new products and therapies to market. At the BIO International Convention last week in Boston, there was lots of discussion about how translational science intersects with patients’ needs and why the best therapeutic developmental pipelines are consistently putting patients first.

As a case in point, Mustafa Sahin, MD, PhD, of Boston Children’s discussed his work to improve testing and translation of new therapies for autism spectrum disorder (ASD). As a member of PACT (Preclinical Autism Consortium for Therapeutics) and director of Boston Children’s Translational Neuroscience Program, Sahin aims to bridge the gap between drug discovery and clinical translation.

“Our mission is to de-risk entry of new therapies in the ASD drug discovery and development space,” said Sahin, who is also a professor of neurology at Harvard Medical School.

One big challenge, says Sahin, is knowing how well — or how poorly — autism therapies are actually affecting people with ASD. Externally, ASD is recognized by its core symptoms of repetitive behaviors and social deficits.

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Solving the DIPG puzzle a single cell at a time

Image depicting the cellular makeup of DIPG/DMG tumors vs normal brain tissue development
Scientists have discovered that DIPG/DMG tumors are made up of H3K27M-mutated cell populations that contain many cells stuck in a stem-cell-like state, fueling tumor growth. Cells that can differentiate despite the H3K27M mutation could hold the key to unlocking a new therapy for DIPG/DMG.

For more than 15 years, pediatric neuro-oncologist Mariella Filbin, MD, PhD, has been on a scientific crusade to understand DIPG (diffuse intrinsic pontine glioma). She hopes to one day be able to cure a disease that has historically been thought of as an incurable type of childhood brain cancer.

“While I was in medical school, I met a young girl who was diagnosed with DIPG,” Filbin recalls. “When I heard that there was no treatment available, I couldn’t believe that was the case. It really made a huge impression on me and since then, I’ve dedicated all my research to fighting DIPG.”

Her mission brought her to Boston Children’s Hospital for her medical residency program and later, to do postdoctoral research at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. Now, she’s starting her own research laboratory focused on DIPG — which has also been called diffuse midline glioma (DMG) in recent years — and continuing to treat children with brain tumors at the Dana-Farber/Boston Children’s pediatric brain tumor treatment center. She’s also a scientist affiliated with the Broad Institute Cancer Program.

This year, Filbin has made new impact in the field by leveraging the newest single-cell genetic sequencing technologies to analyze exactly how DIPG develops in the first place. Her latest research, published in Science, entailed profiling more than 3,300 individual brain cells from biopsies of six different patients.

Using what’s known as a single-cell RNA sequencing approach to interrogate the makeup of DIPG/DMG tumors, Filbin was able to identify a particularly problematic type of brain cell that acts forever young, constantly dividing over and over again in a manner similar to stem cells.

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A bold strategy to enhance CAR T-cell therapies, capable of targeting DIPG and other tough-to-treat cancers

CAR T-cell therapy uses a patient's own genetically modified T cells to attack cancer, as pictured here, where T cells surround a cancer cell.
T cells surround a cancer cell. Credit: National Institutes of Health

A Boston-based team of researchers, made up of scientists and pediatric oncologists, believe a better CAR T-cell therapy is on the horizon.

They say it could treat a range of cancers — including the notorious, universally-fatal childhood brain cancer known as diffuse intrinsic pontine glioma or DIPG — by targeting tumor cells in an exclusive manner that reduces life-threatening side effects (such as off-target toxicities and cytokine release syndrome). The team, led by Carl Novina, MD, PhD, and Mark Kieran, MD, PhD, of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, calls their approach “small molecule CAR T-cell therapy.”

Their plan is to optimize the ability for CAR T-cell therapies, which use a patient’s genetically modified T cells to combat cancer, to more specifically kill tumor cells without setting off an immune response “storm” known as cytokine release syndrome. The key ingredient is a unique small molecule that greatly enhances the specificity of the tumor targeting component of the therapy.

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Failed cancer drug may extend life in children with progeria

child with progeria and damage to cell nucleus
Image: Wikimedia Commons. (Source: The Cell Nucleus and Aging: Tantalizing Clues and Hopeful Promises. Scaffidi P, Gordon L, Misteli T. PLoS Biology Vol. 3/11/2005, e395 doi:10.1371/journal.pbio.0030395)

Hutchinson-Gilford Progeria Syndrome, better known as progeria, is a highly rare genetic disease of premature aging. It takes a cruel toll: Children begin losing body fat and hair, develop the thin, tight skin typical of elderly people and suffer from hearing loss, bone problems, hardening of the arteries, stiff joints and failure to grow. They die at an average age of 14½, typically from heart disease resembling that of old age.

An observational study published yesterday in the Journal of the American Medical Association suggests that a drug called lonafarnib, originally developed as a potential cancer treatment, can extend these children’s lives.

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