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Highlights - Promise Winter 2012


Lead image for Promise Magazine Winter 2012 Highlights page

 


Gene therapy achieves early success against hemophilia B

St. Jude researchers have developed a treatment that offers hope to patients with the bleeding disorder hemophilia B. In a recent clinical trial conducted at the University College London (UCL), symptoms improved significantly in hemophilia B patients following a single gene therapy treatment.

The findings mark the first proof that gene therapy can safely reduce disabling, painful bleeding episodes in patients with the blood disorder. Results of the Phase I study appeared in the New England Journal of Medicine.

Hemophilia B is caused by an inherited mistake in the gene for making a protein called Factor IX, which is essential for normal blood clotting. Previous efforts to ease hemophilia B symptoms by introducing a correct copy of the gene had been unsuccessful. The current study used a harmless virus as the vector to deliver the Factor IX gene along with additional genetic material into each patient’s liver. The vector used in the study was produced at the Good Manufacturing Practices facility on the St. Jude campus. The approach was jointly pioneered by St. Jude and UCL, initially in the lab of study co-author Arthur Nienhuis, MD, of St. Jude Hematology.

As is often the case with experimental therapies, this study was conducted in adults to ensure the treatment was safe and effective. Plans are to include children in future trials. Because they have not yet experienced the joint damage and other complications of the disease, children undergoing gene therapy will likely benefit even more than adults do.

“These results are highly encouraging and support continued research. More patients are scheduled to be enrolled in future trials scheduled to begin later this year,” said the study’s senior author, Andrew Davidoff, MD, St. Jude Surgery chair.

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In-house screening reduces stroke risk

Gail Fortner, RN, uses an ultrasound to measure blood flow in arteries leading to a child’s brain. The procedure, known as transcranial Doppler (TCD) ultrasound, is the most effective tool for predicting primary stroke in patients with sickle cell anemia.

Gail Fortner uses ultrasoundSickle cell patients at St. Jude undergo annual TCD screenings at their regular clinic visits. Most sickle cell centers require patients to go to radiology or neurology appointments to have the test done.

With the knowledge obtained from TCD screenings and the treatment offered to those considered to be at high-risk for strokes, clinicians are able to prevent stroke in many children with sickle cell anemia.

“Today, 99 percent of our high-risk patients ages 2 to 16 are screened for stroke. In published data from other institutions, that number is from 49 to 58 percent,” Fortner said.

She and Beth McCarville, MD, Radiological Sciences, are training Brazilian and Jamaican physicians who will be collaborating with St. Jude and Baylor College of Medicine on a future multicenter trial. This will be the first NIH-funded international sickle cell disease clinical trial and the latest example of the hospital’s collaboration on research that helps to improve the quality of life for sickle cell patients.

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Molecule serves as key in some protein interactions

St. Jude structural biologists Brenda Schulman, PhD, Daniel Scott, PhD, and Julie Monda have identified a mechanism that facilitates some protein interactions that are workhorses of cells. In the process, they have also found a potential new cancer drug development target.

Brenda Schulman, PhD, Daniel Scott, PhD, and Julie MondaThe discovery involves a chemical known as an acetyl group. About 40 to 80 percent of human proteins have this chemical added to the amino acid at one end of the protein during a process known as N-terminal acetylation. Although it has long been recognized that proteins are N-terminally acetylated, until now it was unknown how that process could serve specific functions.

The researchers showed that much like a key must fit precisely to work a lock, the acetylated end of one enzyme fits perfectly into a deep pocket on the surface of another protein. The connection helps accelerate the activity of a protein complex that is involved in regulating cell division and that has been linked to cancer. The research appeared in the journal Science.

The findings have potential implications for drug discovery and for understanding basic mechanisms governing the interaction of possibly thousands of proteins, said Schulman, who is also a Howard Hughes Medical Institute investigator.

“The work presents a major new concept in protein-protein interactions,” she said. “This raises the question of whether similar ‘keys’ on thousands of different proteins also unlock doors to allow them to function.”

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Brain tumor research yields new treatment options

St. Jude investigators have pioneered a new approach to drug development and have identified dozens of potential new treatments for ependymoma, a rare tumor of the brain and spine.

The new system combines the latest drug screening technology with the first accurate laboratory model of the tumor.

Using the method, researchers have identified new and existing drugs as possible ependymoma treatment candidates. The drugs were identified by screening 5,303 existing medicines, natural products and other compounds for activity against the tumor, which affects children and adults.

The list of candidate drugs included 5-fluorouracil (5-FU), which has been widely used to treat adult cancers but has not been formally tested against ependymoma.

Based on study results, St. Jude is now planning a clinical trial of 5-FU in young ependymoma patients, said senior author Richard Gilbertson, MD, PhD, Comprehensive Cancer Center director.

The work was published recently in the scientific journal Cancer Cell.

Researchers hope to use the same system to expand chemotherapy options for patients with other cancers. Rather than waiting years for clinical trial results, this system promises to take just months to provide key information about a drug’s effectiveness and optimal administration.

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Study addresses survivors’ neuromuscular problems

Kirsten Ness, PhD, of St. Jude Epidemiology and Cancer Control, is principal investigator of research that is spurring efforts to address the neuromuscular problems of some cancer survivors.

Kirsten Ness, PhDIn a study recently published in the journal Cancer, Ness and her colleagues found that high doses of two drugs widely used to treat children with acute lymphoblastic leukemia (ALL) left nearly half of adult survivors in their mid-30s with walking, balance and other limitations typical of someone decades older.

The study is the first to document the association between high doses of methotrexate and the muscle, joint and nerve problems that affect some long-term survivors of childhood ALL. Adult survivors whose treatment included high cumulative doses of the drug vincristine were also identified as being at increased risk of reduced ankle flexibility, reduced leg strength and difficulty walking.

The information was collected as part of the St. Jude LIFE study that provides ongoing clinical follow-up to thousands of St. Jude cancer survivors.

“These survivors do not complain of pain or numbness, but many have evidence of a mild motor neuropathy that affects their ability to walk and leaves them at risk for a variety of problems later in life,” Ness said.

Simple stretching and strengthening exercises may help ease the problems, she added.

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Nasal flu vaccine safe for young cancer patients

New St. Jude research demonstrates that both the flu shot and the nasal vaccine are safe for use in young cancer patients. The finding is important because the influenza virus poses a severe risk to cancer patients with immune systems weakened by their disease and treatment. Flu can also cause life-threatening illness and delay chemotherapy.

The new findings will not change recommendations that pediatric cancer patients receive flu shots, which deliver a vaccine made from killed flu viruses, rather than nasal vaccines, which use a different form of influenza virus to trigger a protective immune response. But the research should ease any lingering concerns that pediatric cancer patients will contract flu following direct or indirect exposure to the nasal vaccine.

The vaccine, which is marketed as FluMist, uses live, but weakened flu virus to trigger protection.

The study is the largest yet to compare the safety of the two flu vaccines. Patricia Flynn, MD, Infectious Diseases, was senior author of a paper on this topic, which appeared in the Journal of Infectious Diseases.

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Cover of inaugural issue of Promise magazine

Let us eat cake

Both Promise magazine and St. Jude Children’s Research Hospital are celebrating anniversaries. This is the 50th issue of Promise, which was launched in 1998. This year, the hospital also celebrates a monumental milestone—five decades of finding cures and saving children. Look for a special issue marking the hospital’s anniversary in April of this year…and go ahead: Celebrate!

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Outreach program is national model

A marquee outreach program developed at St. Jude is a national model for raising awareness about sickle cell disease, the world’s most prevalent genetic disorder.

Approximately one in 12 African Americans has sickle cell trait. Sickle cell disease is also prevalent among those of Caribbean, Latin American, Mediterranean or Middle Eastern descent.

The Know Your Sickle Status program, or K.Y.S.S., provides free educational programs and screenings to families affected by sickle cell trait and sickle cell disease. K.Y.S.S. offers awareness education to at-risk populations, particularly teenagers and young adults.

“If one parent has sickle cell trait and the other parent has sickle cell trait or any other abnormal hemoglobin trait, the couple has a one-in-four chance of having a child with sickle cell disease. That’s why it is important for people to know their status,” said Yvonne Carroll, RN, director of Patient Services in St. Jude Hematology.

Coordinated by Charlotte Hoyle of Hematology, the peer education component of K.Y.S.S. targets African-American teenagers and young adults who are at risk for having children with sickle cell disease. St. Jude has one of the largest sickle cell centers in the country. Approximately 800 patients, from infants to teenagers, are treated at the center.

To access sickle cell resources and materials at St. Jude, visit www.stjude.org/sicklecell.

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Hormone research may lead to more targeted drug development

Research led by St. Jude scientists advances a strategy for taming the side effects and enhancing the benefits of steroids and other medications that work by disrupting the activity of certain hormones.

The approach relies on a small molecule developed at St. Jude. In this study, scientists showed that a compound known as SJ-AK selectively blocked the activity of genes in a cell signaling pathway regulated by thyroid hormone. SJ-AK also affected cells growing in the laboratory, reducing cell proliferation as well as the production and secretion of a growth hormone regulated by thyroid hormone.

The research appeared in the journal ACS Chemical Biology.

The findings raise hope that compounds like SJ-AK will lead to drugs with more tailored effects by selectively controlling signaling pathways that switch genes on and off.

“This study offers the first evidence that it is possible to shut down a portion of the signaling network activated by a particular hormone,” said the study’s senior author, R. Kiplin Guy, PhD, chair of Chemical Biology and Therapeutics at St. Jude.

Such selectivity could lead to a new generation of medications with greater effectiveness and fewer side effects. The new treatments could include steroids that fight leukemia or suppress the inflammation associated with autoimmune disorders without affecting metabolism or bone strength.

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