Introduction: Who Should Undergo Diagnostics

If you have been diagnosed with certain types of cancer, especially non-small cell lung cancer or specific forms of lymphoma, your doctor may recommend testing for ALK gene mutations. An ALK gene mutation is a change in the genetic material of your cells that can cause cancer cells to grow and spread. This mutation is not something you inherit from your parents—it develops during your lifetime due to various factors that scientists are still working to understand completely.^[4]

You should consider ALK testing if you have been diagnosed with lung cancer, particularly if you are younger than the typical lung cancer patient, have never smoked or are a light smoker, and have a type of lung cancer called adenocarcinoma. About five percent of people with non-small cell lung cancer have tumors with an ALK gene fusion, which is when the ALK gene joins together with another gene and creates an abnormal protein that drives cancer growth.^[7][16]

People with ALK-positive lung cancer tend to be younger than the average lung cancer patient. The median age at diagnosis is around 52 years, and some patients are diagnosed in their teens or twenties. This type of cancer is commonly found in nonsmokers or light smokers, which makes it particularly important to test for this mutation even if you don’t fit the typical profile of someone at high risk for lung cancer.^[16][17]

Beyond lung cancer, ALK gene changes also appear in other cancers. If you have been diagnosed with anaplastic large cell lymphoma (ALCL), a rare form of cancer affecting white blood cells called T lymphocytes, your doctor will likely test for ALK gene changes. In this lymphoma, the presence or absence of an ALK mutation helps doctors classify your disease and plan your treatment. ALK-positive ALCL is most common in children and young adults and usually responds well to chemotherapy. ALK-negative ALCL, on the other hand, primarily affects older adults and can be more challenging to treat.^[6][14]

People with neuroblastoma, a cancer that develops from immature nerve cells and primarily affects children, should also be tested for ALK gene mutations. At least 16 different mutations in the ALK gene have been identified in some people with neuroblastoma. These mutations can be inherited from a parent in cases of familial neuroblastoma, or they can develop spontaneously during a person’s lifetime in sporadic cases.^[4]

It’s advisable to seek diagnostic testing as soon as you receive a cancer diagnosis that could involve ALK gene changes. The earlier you know whether your cancer has an ALK mutation, the sooner you and your doctor can discuss treatment options that specifically target this genetic change. Waiting to get tested can delay access to targeted therapies that may work better than standard treatments for your specific type of cancer.

Diagnostic Methods

To find out if your cancer has an ALK mutation, you need to undergo biomarker testing. A biomarker is a substance that doctors can measure in tissues, blood, or other body fluids. In the case of ALK-positive cancer, biomarkers are changes in a cell’s genes or proteins that cause the cancer to grow. These mutations are called driver mutations because they drive cancer to grow and spread.^[16]

After being diagnosed with lung cancer or another cancer that might involve ALK, you should ask your doctor for comprehensive biomarker testing. Comprehensive biomarker testing checks your cancer for a full list of biomarkers that doctors have linked to your type of cancer. It is important to know if you have any biomarkers because different treatments work better on cancers with certain biomarkers. This information helps your doctor decide what your treatment options might be.^[16]

There are two main types of biomarker testing: tissue biopsy and liquid biopsy. During a tissue biopsy, doctors use a sharp tool to obtain a sample of tissue from your cancer. For lung cancer, this might involve using a needle inserted through your chest wall or using a thin tube with a camera (called a bronchoscope) that goes down your airway to reach the tumor. The tissue sample is then sent to a laboratory where specialists examine the cells under a microscope and perform molecular tests to look for ALK gene rearrangements or mutations.^[16]

The second testing method is a liquid biopsy. During a liquid biopsy, doctors take a sample of your blood to look for cancer cells from your tumor circulating in your bloodstream. Currently, tissue biopsies are the standard of care if you have enough tissue available, but liquid biopsies are showing potential to be as accurate as tissue biopsies in the future. Liquid biopsies are less invasive than tissue biopsies and can be particularly helpful when it’s difficult or risky to obtain a tissue sample.^[16]

Once your sample reaches the laboratory, scientists use several techniques to detect ALK gene changes. One common method checks for gene rearrangements, which happen when the ALK gene fuses with another gene. The most common fusion in lung cancer is between ALK and a gene called EML4 (echinoderm microtubule-associated protein-like 4). When these two genes join together, they produce an abnormal protein that sends signals telling cells to grow out of control.^[16]

Your doctor might refer to an ALK-positive test result using different terms, including ALK mutation, ALK biomarker, ALK fusion, ALK rearrangement, or ALK-positive cancer. These terms all describe the same basic problem: a change in the ALK gene that causes cancer cells to grow abnormally. Understanding this terminology can help you communicate more effectively with your healthcare team and understand your medical records.^[16]

For patients with anaplastic large cell lymphoma, testing determines whether the cancer is ALK-positive or ALK-negative. This classification is based on whether there is a mutation or change in the ALK gene. The most common genetic change in ALCL is a translocation—an exchange of genetic material—between chromosome 2 (where the ALK gene is located) and chromosome 5. This creates a fusion between the ALK gene and another gene called NPM. The resulting abnormal protein drives the cancer cells to grow.^[2][14]

In neuroblastoma, testing looks for specific mutations that change single building blocks (amino acids) in the ALK protein. The most common mutation replaces one amino acid called arginine with another amino acid called glutamine at a specific position in the protein. This mutation, written as R1275Q, has been found in both inherited (familial) and spontaneous (sporadic) cases of neuroblastoma. Sometimes, extra copies of the ALK gene are found in neuroblastoma cells, a phenomenon called gene amplification, which results in too much ALK protein being produced.^[4]

The diagnostic process also involves distinguishing ALK-positive cancers from other types of cancer with similar appearances. For lung cancer, doctors need to rule out other driver mutations such as changes in the EGFR, KRAS, or ROS1 genes, which also affect treatment decisions. For lymphoma, pathologists examine the size and appearance of cancer cells under a microscope and perform additional tests to confirm the diagnosis and determine the ALK status.^[6]

Diagnostics for Clinical Trial Qualification

When you are considering joining a clinical trial to test new treatments for ALK-positive cancer, you will need to undergo specific diagnostic tests that serve as standard criteria for enrolling patients. Clinical trials have strict eligibility requirements to ensure that the people participating are likely to benefit from the experimental treatment and that the trial results will be scientifically valid.

For clinical trials involving ALK inhibitors—drugs that target the abnormal ALK protein—you must have confirmed ALK-positive disease. This confirmation typically requires molecular testing of your cancer tissue using validated laboratory methods. The trial may specify which testing methods are acceptable, such as specific genetic sequencing techniques or approved diagnostic tests that have been shown to reliably detect ALK gene changes.^[12]

In addition to confirming your ALK-positive status, clinical trials often require tests to assess your overall health and the stage of your cancer. These tests might include imaging scans such as computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, or positron emission tomography (PET) scans. These imaging tests help doctors see where the cancer is located in your body, how large the tumors are, and whether the cancer has spread to other organs. This information determines your cancer stage, which is important for trial eligibility.^[12]

Many clinical trials for ALK-positive lung cancer specifically enroll patients with advanced or metastatic disease, which means the cancer has spread to distant parts of the body such as the liver, bones, or brain. If you have cancer that has spread to your brain, some trials may require special brain imaging with MRI to measure the size and location of brain tumors. This is particularly important because some ALK inhibitors work better than others at reaching the brain and controlling cancer that has spread there.^[12]

Blood tests are another standard component of clinical trial qualification. These tests check how well your organs are functioning, particularly your liver and kidneys, which need to process and eliminate the study drug from your body. Your blood counts are also measured to ensure you have enough healthy blood cells to tolerate the treatment. If your organ function or blood counts are too abnormal, you may not be eligible for certain trials because the experimental treatment could be unsafe for you.

Some clinical trials compare newer ALK inhibitors to older ones or to chemotherapy. For these trials, you may need documentation of how you responded to previous treatments. For example, if a trial is testing a second-generation ALK inhibitor in patients who have already received a first-generation ALK inhibitor like crizotinib, you would need proof that your cancer grew despite treatment with crizotinib. This documentation might include imaging scans showing tumor growth or biopsy results confirming that your cancer has developed resistance to the previous drug.^[12]

In some advanced research studies, doctors may want to test for specific resistance mutations that develop in the ALK gene after treatment with ALK inhibitors. When cancer cells are exposed to drugs targeting ALK, they sometimes develop additional mutations in the ALK gene that make the drug stop working. Identifying these resistance mutations through repeat biopsies or liquid biopsies can help determine which next-generation ALK inhibitor might work best for you. Some clinical trials specifically enroll patients based on the type of resistance mutation they have developed.

For pediatric clinical trials involving neuroblastoma patients with ALK mutations, additional tests might be needed to assess disease burden. These could include bone marrow biopsies to check if cancer cells have spread to the bone marrow, urine tests to measure certain substances produced by neuroblastoma cells, or specialized imaging scans called MIBG scans that use radioactive material to highlight neuroblastoma cells throughout the body.

The diagnostic requirements for clinical trial qualification are designed to protect your safety and maximize the chances that the experimental treatment will help you. While the testing process can feel overwhelming, especially if you have already undergone many tests for your initial diagnosis, these additional evaluations provide your doctors with the detailed information they need to make informed decisions about your care and determine if a particular clinical trial is right for you.