New Drug Target for Acute Myeloid Leukemia

Acute Myeloid Leukemia therapy targets PRC2 chromatin regulator

Reviewed By: Joseph V. Madia, MD

By: Travis Giddings

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Researchers are always looking for new ways to selectively attack cancers while leaving healthy cells alone, as many of the most common treatments for cancer involve some unfortunate friendly fire.

In that spirit, a group of scientists have found a piece of cellular machinery that is essential for leukemia cells, but not for healthy cells.

Targeting the PRC2 chromatin regulator, a protein that edits DNA, effectively destroys the ability of cancer cells in acute myeloid leukemia to reproduce.

Ask your oncologist about clinical trials available near you.

Researchers from the Cold Spring Harbor Laboratory used the Nobel Prize winning technology called RNA interference to identify the cellular target, known as Brd4, (part of the chromatin regulator PRC2). Develoment of a drug targeting Brd4 is already underway.

“In our new screen, PRC2 was one of the few chromatin regulators that was needed by cancer cells, but dispensable for normal blood cells,” stated an author of the study, Eric Wang.

The ability of healthy cells to live without PRC2 means that this drug would destroy cancerous cells and leave normal non-cancerous cells unaffected.

The study used specific strains of mice bred for previous research on leukemia. Researchers tests possible molecular targets in series until a likely candidate was found.

Research was published April 3, 2012 in the journal Oncogene, link available below.

Funding for the Cold Spring Harbor Laboratory’s research falls under its auspice as a private, not-for-profit institution.

Leukemia

According to the Leukemia and Lymphoma Society, there are over 245,000 people in the United States living with some form of leukemia, and over 44,000 new cases will be diagnosed each year. Among children with cancer, one out of every three will have some form of leukemia. However, over 90% of all cases of leukemia occur in adults.

Leukemia broadly defines a number of different cancers that originate in the bone marrow and blood cell lines, and typically produces an abnormal increase in the number of white blood cells in the body. Leukemias are subdivided into whether they are acute (occur rapidly) or chronic (develop over many years) and then further subdivided into what type of blood cell they start from, lymphocytic (usually from white blood cells that fight infection, like B-cells) or myelogenous (arising from cells in the bone marrow that eventually produce red blood cells). These categories make up the four most common types of leukemia:

Acute Lymphoblastic (ALL): Affects adults over age 65 (50% survival); also the most common form of leukemia in children (85% survival)
Chronic Lymphocytic (CLL): Affects mostly men over age 55 (75% survival)
Acute Myelogenous (AML): Affects mostly adult men (40% survival)
Chronic Myelogenous (CML): Affects mainly adults (90% survival)

Each of these general forms of leukemia is further subdivided into the type of cell that is affected, and treatments differ based on what the root cause is. There are also other types of leukemia that do not generally fit into any of these categories, such as Hairy cell leukemia, Adult T-cell leukemia, and T-cell prolymphocytic leukemia, an extremely rare and aggressive cancer.

There is no single cause for all the different types of leukemia. Research has shown that there is a predisposition for certain leukemias to run in families. Environmental factors such as exposure to the chemical benzene as well as other petrochemicals have been linked as well. People who have received certain types of chemotherapy (alkylating agents; and topoisomerase inhibitors) and people exposed to large amounts of radiation are also at greater risk. While not a direct risk factor, cigarette smoking has been linked to an increased risk of developing leukemia.

Symptoms of leukemia can be similar to those of other less serious diseases, and patients will have the disease discovered with blood testing and pathological examination of the blood cells. Common symptoms include fevers and night sweats, feeling fatigue and weakness, bleeding and bruising easily, frequent infections (from non-functioning immune cells), unexplained weight loss, and pain in the bones and joints. Some patients may notice swollen lymph nodes in the armpits or neck that are painless when touched.

Treatment is dependent on the type of leukemia, as certain forms are responsive to specific chemotherapies and radiation treatments, while others may not be. Newer therapies such as targeted therapy and biologic agents are being used more frequently as well. Some forms of leukemia are treated with a bone marrow transplant, which entails replacing the entire blood cell producing system. Acute leukemias are life-threatening, so they are immediately and aggressively treated, while chronic leukemias may not require treatment for several years.

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