ALK Gene and Cancer

February 18, 2026

This page was reviewed under our medical and editorial policy by Christine Lovly, M.D., Ph.D., professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte.

The ALK gene, short for anaplastic lymphoma kinase gene, is present in every person and plays a role in how cells grow and function. More specifically, it is thought to support developing nerve cells in the womb.

Under normal conditions, the ALK gene produces a protein that helps control cell growth. However, in some cancers like neuroblastoma and non-small cell lung cancer (NSCLC), the ALK gene may change in ways that cause cancer cells to grow. Once that change happens, it’s known as an ALK fusion or ALK rearrangement.

Testing for these changes in a tumor may give the patient’s care team valuable information to guide treatment, especially if the ALK rearrangement is driving cancer growth.

What Is an ALK Fusion?

An ALK rearrangement is a change in the ALK gene that affects how certain cells grow and divide. For example, the gene may fuse with another gene or become rearranged.

Normally, the ALK gene provides instructions for making a protein called ALK receptor tyrosine kinase to help develop certain cells and allow them to grow and mature.

However, when the ALK gene changes in a tumor cell, it may disrupt the normal process and turn the gene on when it should not be on. These rearrangements turn the ALK gene into what is called an oncogene. This means it causes cells to grow more rapidly than normal and may contribute to cancer development. Researchers are able to test cancer cells for some genetic changes, like ALK fusions.

The results of this testing may help doctors understand how the patient’s cancer might behave and which treatments may be beneficial. 

ALK Fusion and Lung Cancer

An ALK rearrangement may be found in up to 5% of non-small cell lung cancer patients.

ALK fusions in lung cancer are often seen in younger patients who have not smoked, but other lung cancer patients may have it, too. When a lung cancer patient tests positive for an ALK rearrangement, it opens up different treatment options. When ALK fusion is detected in the tumor, doctors may refer to it as ALK-positive cancer.

For advanced ALK-positive NSCLC, doctors may recommend ALK tyrosine kinase inhibitors (TKIs), which are drugs that specifically target the ALK rearrangement and block the abnormal ALK protein. These drugs, taken as pills, help block cancer growth. There are several generations of ALK TKIs:

Lorlatinib (Lorbrena^®): A third-generation ALK tyrosine kinase inhibitor, which was designed to be more potent at blocking ALK and to be highly penetrant into the central nervous system.

Alectinib (Alecensa^®), brigatinib (Alunbrig^®), ceritinib (Zykadia^®) and ensartinib (Ensacove^®): Second-generation inhibitors, these are also more successful than the earliest ALK inhibitor at penetrating the blood-brain barrier.

Crizotinib (Xalkori^®): This is the first-generation, earliest ALK inhibitor, and may still used.

Some patients with early-stage ALK-positive NSCLC may also receive an ALK inhibitor after surgery to reduce the chance of cancer returning.

ALK Mutation and Neuroblastoma

Neuroblastoma is a type of cancer that mostly affects children. It begins when immature nerve cells, called neuroblasts, start to grow uncontrollably and form a tumor.

This tumor often starts in the nerve tissue of the adrenal gland, located above each kidney, but it may also develop in other areas. Sometimes, neuroblastoma spreads to other parts of the body, including the bones, liver or skin.

A change, or mutation, in the ALK gene is a key factor in many cases of neuroblastoma. When the gene mutates, it may create a constantly active version of the ALK protein. Researchers think this constant “on” position may cause nerve cells to grow abnormally, leading to neuroblastoma.

ALK Gene and Other Cancers

While ALK changes are most common in lung cancer and neuroblastoma, they may also occur in other types of cancer.

For example, ALK changes may play a role in anaplastic large cell lymphoma (ALCL), a type of cancer that affects immune cells called T cells. In many ALCL cases, a translocation occurs — genetic material from the chromosome where the ALK gene is located swaps with another chromosome. This may create a new protein that encourages cancer growth.

ALK changes are also found in inflammatory myofibroblastic tumors (IMTs), another rare cancer which is more common in children. About half of IMT cases involve an ALK rearrangement, which may lead to abnormal cell growth in the tumor.

ALK Testing

Testing for changes in the ALK gene involves taking a sample of cancer cells to check for specific gene changes. If the cancer is in a solid tumor, doctors usually use tissue from a biopsy or surgery. Sometimes, when it is difficult to get a tissue sample, a blood test (or liquid biopsy) might be performed instead, as it may contain tumor cells. Patients might also be asked to provide a sample from healthy cells in the blood or saliva to use for comparison.

Once collected, these samples go to a lab where doctors look for biomarkers like ALK fusions. The results help the care team evaluate potential treatments and whether the rearrangement was spontaneous or inherited.

ALK Gene Test Results

The timing of ALK genetic test results will depend on the type of test and whether the sample needs to be sent to a specialized lab. When results are ready, they are reported to the care team, who reviews them with the patient.

If the test shows an ALK mutation or rearrangement, it means the patient’s cancer cells have a specific change that might be targeted by certain treatments. Testing positive for an ALK mutation or rearrangement may open up options like new treatments approved by the U.S. Food and Drug Administration or clinical trials focused on ALK-targeted therapies.

If there is no ALK change detected, some treatments may be less appropriate. This may help patients avoid unnecessary therapies. The care team will explain what each finding means and how it could affect treatment options.