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What is Targeted Therapy?

Updated: Feb 2

Per the National Cancer Institute, “targeted therapy is a type of cancer treatment that targets proteins that control how cancer cells grow, divide, and spread.” The following explains why targeted therapy is the standard of care in many countries for patients who have metastatic (stage IV) ROS1+ non-small cell lung cancer (NSCLC).

Targeted Therapy vs. Chemotherapy

Targeted therapy drugs, like other drugs used to treat cancer, are technically considered chemotherapy. However, traditional chemotherapy targets ALL cells that grow and divide quickly, whether they are cancer cells or healthy cells. This oftentimes leads to difficult side effects. Most types of targeted therapy only interfere with specific proteins that help tumors grow and spread throughout the body.

There are many types of targeted therapies. Lung cancer targeted therapy zeros in on proteins that are present only in cancer cells, and generally leaves other healthy cells alone.

Since these targeted therapy drugs only target cancer cells, side effects tend to be less than with traditional chemotherapy. Many ROS1+ cancer patients find they can have relatively normal lives while taking a targeted therapy drug.

How Targeted Therapy Works

For ROS1+ cancer, the targeted therapy binds to the ROS1 protein in the cells. When the drug binds to the ROS1 protein, it blocks or turns off chemical signals that tell the cancer cell to grow and divide. When the cell no longer grows or divides, the cancer stops growing and the cell can die.

ROS1 targeted therapies help to control and shrink the cancer cells in your body. But they cannot kill 100% of the cancer cells, nor do they cure cancer. Some patients find this targeted therapy will effectively control their cancer for years, and some may see their tumors disappear completely. However every patient’s response to the targeted therapy is unique - some will find their targeted therapy is effective only for a few months and others find it may not work at all.

Side Effects of Targeted Therapy

Targeted therapy drugs have different side effects than traditional chemotherapy. There are many types of targeted therapies, and each drug has its own side effects, varying from mild to severe. Generally speaking, the side effects with targeted therapy are less severe than those with traditional chemotherapy. However, each person’s reaction to treatment is unique and there can be severe side effects even in targeted therapy drugs.

Read more about coping with the side effects of ROS1 targeted therapy treatments.

ROS1 Targeted Therapies

In clinical trials, ROS1 targeted therapies are more effective and more tolerable than standard chemotherapy. Two targeted therapies have been approved for ROS1+ cancer in the US and some other countries. Patients who cannot tolerate one targeted therapy may be able to switch to a different, more tolerable drug. Effective first-line ROS1 targeted therapies (for patients who have never taken a targeted therapy) include:


Entrectinib was approved by the FDA in 2020 and effectively treats the brain, and is emerging as the preferred targeted therapy for ROS1+ NSCLC. Treating the brain is important because nearly half of ROS1+ cancer patients will eventually develop brain metastases. However, it does have neurologic side effects that may require a dose reduction or switch to a different therapy for some patients.


Crizotinib was approved by the FDA in 2016. Crizotinib does not treat the brain effectively, but many ROS1ders who were treated with crizotinib have thrived for years with no brain metastases and good quality of life–some even achieved and maintained no evidence of disease.


Ceritinib is not approved for ROS1+ cancer, but is available off-label (“off-label” refers to using approved drugs for an unapproved use). It does treat the brain, but is not as effective for ROS1+ cancer as the other targeted therapies above, and seems to have more side effects for some patients. However, it is more available in some countries than crizotinib or entrectinib, so it may be an alternative if crizotinib or entrectinib are not tolerable.

There are other targeted therapies for ROS1+ cancer treatment, but they do not have regulatory approval. Second-line targeted therapies may be useful when a patient develops acquired resistance to one of these targeted therapies.

How Can You Learn More?

ROS1+ cancer is so rare that oncologists can be forgiven for not knowing everything about it when they give you your diagnosis. Even very large cancer centers may have encountered only a few ROS1+ patients. That means that you may need to partner with your oncologist to stay on top of information about what’s needed and what’s new.

Learn more about all ROS1 targeted therapies.

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The ROS1ders offer several ways to connect with our community. Please visit our Connect To Our Community page to find out more.

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