PRINCIPLES, BENEFITS AND CHALLENGES OF TARGETED THERAPY FOR CANCER

Cancer is a disease that occurs when cells in the body grow out of control and form abnormal masses or tumors. Cancer cells can spread to other parts of the body and interfere with normal functions. There are many different types of cancer, each with its own causes, symptoms, and treatments.

One of the most promising treatments for cancer is targeted therapy. Targeted therapy is a type of cancer treatment that uses drugs or other substances to precisely identify and attack certain types of cancer cells. Unlike chemotherapy, which often kills all cells that grow and divide quickly, targeted therapy only affects the cancer cells that have specific characteristics or targets.

In this article, we will explain what targeted therapy is, how it works, what are the different types of targeted therapy, what are the benefits and challenges of targeted therapy, and how it is used in combination with other treatments. We will also provide some examples of targeted therapy drugs that are approved for specific types of cancer.

## What is targeted therapy?

Targeted therapy is a type of cancer treatment that targets proteins that control how cancer cells grow, divide, and spread. It is the foundation of precision medicine. As researchers learn more about the DNA changes and proteins that drive cancer, they are better able to design treatments that target these proteins.

Targeted therapy can be used by itself or in combination with other treatments, such as traditional or standard chemotherapy, surgery, or radiation therapy. Targeted therapy can help shrink tumors, slow down their growth, prevent them from spreading, or make them more sensitive to other treatments.

## How does targeted therapy work against cancer?

Most types of targeted therapy help treat cancer by interfering with specific proteins that help tumors grow and spread throughout the body. These proteins can be on the surface of cancer cells or inside them. Some of these proteins are also found on normal cells, but they are more abundant or active on cancer cells.

The following explains the different ways that targeted therapy treats cancer:

– Help the immune system destroy cancer cells. One reason that cancer cells thrive is because they can hide from your immune system. Certain targeted therapies can mark cancer cells so it is easier for the immune system to find and destroy them. Some examples of these therapies are monoclonal antibodies, such as pembrolizumab (Keytruda) and atezolizumab (Tecentriq), which block a protein called PD-1 or PD-L1 that helps cancer cells evade immune attack.

– Stop cancer cells from growing by interrupting signals that cause them to grow and divide without order. Healthy cells have signals that tell them when to grow and when to stop growing. Cancer cells often have mutations or changes in their DNA that make these signals go haywire. Targeted therapies can block these signals and stop cancer cells from multiplying uncontrollably. Some examples of these therapies are tyrosine kinase inhibitors (TKIs), such as erlotinib (Tarceva) and imatinib (Gleevec), which block enzymes called tyrosine kinases that are involved in many cell signaling pathways.

– Stop blood vessels from forming around tumors by blocking a protein called vascular endothelial growth factor (VEGF). Tumors need blood vessels to supply them with oxygen and nutrients. VEGF is a protein that stimulates the formation of new blood vessels around tumors. Targeted therapies can block VEGF and starve tumors of their blood supply. Some examples of these therapies are bevacizumab (Avastin) and sorafenib (Nexavar), which are anti-angiogenic drugs that inhibit VEGF.

– Deliver toxins or radiation directly to cancer cells by attaching them to molecules that target specific proteins on cancer cells. Some targeted therapies can act as vehicles or carriers for delivering toxic substances or radiation directly to cancer cells, while sparing normal cells. These substances or radiation can kill cancer cells or make them more sensitive to other treatments. Some examples of these therapies are antibody-drug conjugates (ADCs), such as trastuzumab emtansine (Kadcyla) and brentuximab vedotin (Adcetris), which link monoclonal antibodies to chemotherapy drugs; and radioimmunotherapy (RIT), such as ibritumomab tiuxetan (Zevalin) and tositumomab (Bexxar), which link monoclonal antibodies to radioactive substances.

## What are the types of targeted therapy?

Most targeted therapies are either small-molecule drugs or monoclonal antibodies.

– Small-molecule drugs are small enough to enter cells easily, so they are used for targets that are inside cells. They can be taken orally or intravenously. They are usually given daily or weekly.

– Monoclonal antibodies, also known as therapeutic antibodies, are proteins produced in the lab. These proteins are designed to attach to specific targets found on cancer cells. They are usually given intravenously. They are usually given every few weeks or months.

Some targeted therapies are classified according to the type of target they affect. For example:

– Hormone therapy is a type of targeted therapy that blocks or lowers the amount of hormones that stimulate the growth of some types of cancer, such as breast and prostate cancer. Hormone therapy can be given as pills, injections, implants, or surgery. Some examples of hormone therapy drugs are tamoxifen (Nolvadex) and leuprolide (Lupron).

– Gene therapy is a type of targeted therapy that introduces new genes into cancer cells or normal cells to make them behave differently. Gene therapy can be used to replace faulty genes, enhance immune response, or make cancer cells more sensitive to other treatments. Gene therapy is still experimental and not widely available.

– Cell therapy is a type of targeted therapy that uses living cells to treat cancer. Cell therapy can involve modifying the patient’s own immune cells or using donor cells to fight cancer. Cell therapy can also involve transplanting stem cells or organoids to replace damaged tissues or organs. Cell therapy is still experimental and not widely available.

## What are the benefits of targeted therapy?

Targeted therapy has several benefits over traditional chemotherapy, such as:

– It can be more effective for some types of cancer that have specific targets that can be blocked or attacked by targeted therapies.

– It can cause fewer and less severe side effects than chemotherapy, because it does not affect normal cells as much as chemotherapy does.

– It can be used in combination with other treatments, such as chemotherapy, surgery, or radiation therapy, to enhance their effectiveness or overcome resistance.

– It can be personalized based on the genetic profile of the patient’s tumor or the biomarkers that indicate the presence of certain targets.

## What are the challenges of targeted therapy?

Targeted therapy also has some challenges and limitations, such as:

– It may not work for all types of cancer or all patients with a certain type of cancer, because not all tumors have the same targets or respond to the same therapies.

– It may cause serious or unexpected side effects, such as allergic reactions, infections, bleeding, liver damage, heart problems, or skin problems.

– It may become less effective over time, because cancer cells can develop resistance to targeted therapies by changing their targets or finding alternative ways to grow and spread.

– It may be expensive and not covered by insurance, because targeted therapies are often newer and more costly than chemotherapy drugs.

– It may require frequent testing and monitoring, because targeted therapies need to be matched to the patient’s tumor characteristics and adjusted according to the response and side effects.

## How is targeted therapy used in combination with other treatments?

Targeted therapy can be used in different ways in combination with other treatments, such as:

– As a first-line treatment for some types of cancer that have specific targets that can be blocked or attacked by targeted therapies. For example, trastuzumab (Herceptin) is a monoclonal antibody that targets a protein called HER2 that is overexpressed in some types of breast cancer. Trastuzumab is often given with chemotherapy as a first-line treatment for HER2-positive breast cancer.

– As a second-line treatment for some types of cancer that have stopped responding to standard chemotherapy or other treatments. For example, cetuximab (Erbitux) is a monoclonal antibody that targets a protein called EGFR that is involved in cell growth and survival. Cetuximab is often given with chemotherapy as a second-line treatment for colorectal cancer that has spread and has an EGFR mutation.

– As a maintenance treatment for some types of cancer that have responded well to initial treatment but still have a risk of recurrence. For example, olaparib (Lynparza) is a small-molecule drug that inhibits an enzyme called PARP that helps repair DNA damage in cells. Olaparib is often given as a maintenance treatment for ovarian cancer that has responded well to chemotherapy and has a BRCA mutation.

– As an adjuvant treatment for some types of cancer that have been removed by surgery but still have a risk of recurrence. For example, dabrafenib (Tafinlar) and trametinib (Mekinist) are small-molecule drugs that block enzymes called BRAF and MEK that are involved in cell signaling pathways. Dabrafenib and trametinib are often given as adjuvant treatments for melanoma that has been removed by surgery but has a BRAF mutation.

## Conclusion

Targeted therapy is a type of cancer treatment that uses drugs or other substances to precisely identify and attack certain types of cancer cells. Targeted therapy can be more effective and less toxic than chemotherapy for some types of cancer that have specific targets. Targeted therapy can also be used in combination with other treatments, such as chemotherapy, surgery, or radiation therapy, to enhance their effectiveness or overcome resistance.

However, targeted therapy also has some challenges and limitations, such as not working for all types of cancer or all patients, causing serious or unexpected side effects, becoming less effective over time, being expensive and not covered by insurance, and requiring frequent testing and monitoring.

Therefore, targeted therapy is not a one-size-fits-all solution for cancer, but rather a personalized and precise approach that needs to be tailored to each patient’s tumor characteristics and response. Targeted therapy is still evolving and improving as researchers discover new targets, design new drugs, and test new combinations.

If you are interested in learning more about targeted therapy or finding out if it is an option for you or your loved one, please talk to your doctor or visit our website at #CHECKUP CANCER. We are a company that provides comprehensive oncology services, including diagnosis, treatment, follow-up, and support for cancer patients and their families. We are committed to delivering high-quality care and improving outcomes for our patients.

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## References:

(1) Targeted Therapy. https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/targeted-therapy.html.

(2) Targeted Therapy for Cancer – NCI. https://www.cancer.gov/about-cancer/treatment/types/targeted-therapies.

(3) Targeted Therapy Drug List by Cancer Type – NCI. https://www.cancer.gov/about-cancer/treatment/types/targeted-therapies/approved-drug-list.

(4) Targeted Drug Therapy | American Cancer Society. https://www.cancer.org/cancer/managing-cancer/treatment-types/targeted-therapy.html.