In a prime example of finding new uses for older drugs, studies in zebrafish show that a 50-year-old antipsychotic medication called perphenazine can actively combat the cells of a difficult-to-treat form of acute lymphoblastic leukemia (ALL). The drug works by turning on a cancer-suppressing enzyme called PP2A and causing malignant tumor cells to self-destruct.
The findings suggest that developing medications that activate PP2A, while avoiding perphenazine's psychotropic effects, could help clinicians make much-needed headway against T-cell ALL, and perhaps other tumors as well.
A study team led by 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, reported the results Jan. 9 in the Journal of Clinical Investigation.
T-ALL is rarer and more aggressive than the B-cell form of ALL, and it has a relatively poor prognosis. Despite improvements in the treatments available, 20 percent of children and more than 50 percent of adults diagnosed with T-ALL succumb to it.
To identify possible new treatment options, Gutierrez, Look and their collaborators screened a library of 4,880 compounds—including FDA-approved drugs whose patents had expired, small molecules and natural products—in a model of T-ALL engineered using zebrafish.
Strategies that identify new uses for existing drugs have grown in popularity in recent years as a way of quickly developing new disease therapies. Zebrafish models are cost-effective platforms for rapidly conducting drug screens, as well as basic stem cell, genetic, cancer and developmental research.
"We wanted to see if there were drugs or known bioactive molecules that are active against T-ALL that hadn't been tested yet," Look explained. "There may be drugs available for other indications that could be readily repurposed if we can show activity."
One of the strongest hits in the zebrafish screen was the drug perphenazine. It is a member of the phenothiazines, a family of antipsychotic medications used for 50 years, because they can block dopamine receptors.
The team verified perphenazine's anti-leukemic potential in vitro in several mouse and human T-ALL cell lines. Biochemical studies indicated that perphenazine's anti-tumor activity is independent of its psychotropic activity, and that it attacks T-ALL cells by turning on PP2A.
The fact that perphenazine works by reactivating a protein shut down in cancer cells is itself novel in the drug development field.
"We rarely find potential drug molecules that activate an enzyme," Gutierrez explained. "Most new drugs deactivate some protein or signal that the cancer cell requires to survive. But, here, perphenazine is restoring the activity of PP2A in the T-ALL cell."
Gutierrez and Look, along with their collaborators, are now working to better understand the interactions between PP2A and perphenazine. They also want to search for or develop molecules that bind to and activate the enzyme more tightly and specifically to avoid perphenazine's psychiatric effects.
"The challenge is to use medicinal chemistry to develop new PP2A inhibitors similar to perphenazine and the other phenothiazines, but to dial down dopamine interactions and accentuate those with PP2A," Look said.
The researchers see future PP2A inhibitors not as magic bullets but as potentially important additions to the oncologist's arsenal when treating patients with T-ALL.
" T-ALL patients are often on the borderline between a long remission and a cure," Look said. "If we can push the leukemia cells a little harder, we may get more patients who are actually cured. In this way, PP2A inhibitors may, in combination with other drugs, make a real difference for patients."
It may be that the benefits of PP2A-activating drugs could extend beyond T-ALL. "The proteins that PP2A suppresses, such as Myc and Akt, are involved in many tumors," Look noted. "We are optimistic that PP2A activators will have quite broad activity against different kinds of cancer, and we're anxious to study the pathway in other malignancies as well."
This study was supported by the National Cancer Institute (grant numbers K08CA133103 and P01CA109901), the Leukemia and Lymphoma Society, the William Lawrence Blanche Hughes Foundation, the Bear Necessities Foundation, the Ligue Nationale contre le Cancer, Association Laurette Fugain, Institut National du Cancer (INCA), Universités Paris Diderot and Paris Sud, INSERM, CEA and Canceropole Ile de France, European Union's Seventh Framework Programme and the American Society of Hematology.
The Dana-Farber/Boston Children's Cancer and Blood Disorders Center brings together two internationally known research and teaching institutions that have provided comprehensive care for pediatric oncology and hematology patients since 1947. The Harvard Medical School affiliates share a clinical staff that delivers inpatient care at Boston Children's Hospital and outpatient care at the Dana-Farber Cancer Institute's Jimmy Fund Clinic. Dana-Farber/Boston Children's brings the results of its pioneering research and clinical trials to patients' bedsides through five clinical centers: the Blood Disorders Center, the Brain Tumor Center, the Hematologic Malignancies Center, the Solid Tumors Center, and the Stem Cell Transplant Center.
Irene Sege | EurekAlert!
Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung
High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences