What is targeted cancer therapy?
Cancer cells grow and proliferate endlessly. Targeted therapy to stimulate cell death or “apoptosis” can help keep tumors in check.
Targeted cancer therapy is a focused treatment for certain cancers in which the specific cancer-causing factors can be identified and targeted with drugs. Targeted therapy involves administration of medications that alter the way cancer cells function at the cellular level and stop their spread.
Traditional therapies such as chemotherapy and radiation kill cancer cells because they are toxic to cells (cytotoxic), healthy and cancerous alike. Targeted therapy’s goal is to induce a programmed death (apoptosis) of cancer cells alone and preserve the healthy cells as much as possible.
Two types of drug formulations are used in targeted cancer therapies:
- Small molecule drugs: Minute particles that attach to proteins on the cell surface or get right inside the cell and modify its activity.
- Monoclonal antibodies: Larger molecules that cannot get inside the cell, but attach to the cell surface and activate immune activity.
How does cancer start?
Cancer is a unique group of diseases resulting from certain mutations in genes that regulate growth and development, which enable uncontrolled cell growth and proliferation. Cancers most often start in a cell during cell division due to DNA damage or errors while copying (transcription) DNA.
Genetic mutations are most often caused by hereditary factors, environmental factors and certain viral infections, but can sometimes happen for no fathomable reason. Cancer can develop in any part of the body and spread to other parts in a process known as invasion and metastasis. Cancer cells can also develop resistance to medications.
What is apoptosis and its purpose?
Normal cells have a finite cell cycle of growth, division into two daughter cells, and differentiation into specialized cells with specific functions. The final stage in the cell cycle is apoptosis, or programmed cell death, when they are infected, old, damaged or simply no longer needed. This promotes continued regeneration of healthy new cells.
Apoptosis is a programmed death that individual cells undergo to benefit the health and survival of the whole organism. An apoptotic cell withdraws from the neighboring cells, shrinks and disintegrates into a neat packet, which immune cells called phagocytes engulf and digest such apoptotic cells.
Apoptosis is strictly regulated by enzymes known as caspases which cleave the proteins in the cells when activated. Caspases are present in an inactive form in all cells, and when a caspase is activated, it triggers a cascade of downstream activity in all the caspases present in the cell. The caspases cleave all the proteins in the cell, which results in apoptosis.
The caspases may be activated in two ways:
- Extracellular signals: Cell surfaces have proteins known as death receptors which can be activated by proteins on the surface of killer immune cells such as lymphocytes. Lymphocytes usually activate apoptosis when they recognize signs of infection in a cell.
- Intracellular signals: During cell division, DNA damage or errors during transcription of DNA cause release of certain proteins which activate caspase activity. Stress signals from the cell due to insufficient oxygen (hypoxia) or certain nutrients also can initiate apoptosis.
Why is apoptosis important in cancer?
Cancer cells breach several cellular mechanisms that regulate the cell cycle, to grow and proliferate endlessly. Such unregulated growth can be maintained only by also evading apoptosis, which is one of cancer’s most important survival strategies.
Genetic mutations in the cancer cells lead to defects in cell-signaling systems that initiate apoptosis. The cancer cells hijack the family of proteins that regulate apoptosis, silence the pro-apoptosis proteins and overproduce the anti-apoptosis proteins.
What are the targeted cancer therapies for promoting apoptosis?
Therapies targeting apoptosis activate the proteins that promote apoptosis and block the activity of anti-apoptotic proteins. Targeted therapy for promoting apoptosis includes both small molecule drugs that can activate caspases inside the cell and monoclonal antibodies that activate receptors on the cell surface.
Bcl-2 are a family of apoptotic proteins that regulate the intracell apoptosis signaling. To activate the caspases and initiate apoptosis, the mitochondria (a cellular organelle that helps burn calories and other functions) releases a protein known as cytochrome c. Different proteins in the Bcl-2 family either suppress or promote the release of cytochrome c by altering the permeability of the mitochondrial membrane.
Cancer cells have excessive presence of the type of Bcl-2 proteins that block the mitochondria from releasing cytochrome c. Bcl-2 inhibitors are therapies that are targeted to overcome the activity of anti-apoptotic Bcl-2 proteins, enable the release of cytochrome c from the mitochondria, and initiate apoptosis.
Many Bcl-2 inhibitors are in various stages of clinical trials, but only one is FDA-approved:
- Venetoclax (Venclexta)
Approved for adult patients with:
- Chronic lymphocytic leukemia (CLL)
- Small lymphocytic lymphoma (SLL)
- Newly diagnosed acute myeloid leukemia (AML) in adults 75 years or older, who cannot have other therapy
Antisense therapy for IAPs
The inhibitor of apoptosis (IAP) family of genes encode proteins that suppress extracellular and intracellular signals and protect the cancer cell from apoptosis. A particular gene in the IAP family known as X-linked inhibitor of apoptosis (XIAP) is extremely potent in preventing apoptosis.
Many cancers have a high presence of the XIAP proteins encoded by the XIAP gene. Small molecule antisense medications attach to the XIAP gene in the messenger RNA (mRNA), a tiny molecule that is involved in the transcription of DNA, and arrest the transcription process and activation of the XIAP gene.
Antisense is the non-coding strand of the DNA which the mRNA uses as a template for copying. Antisense therapy makes the cancer cells more sensitive to apoptotic signals and chemotherapy. Currently antisense therapies are in the early phases of trials.
Death receptors are proteins on the cell surface which activate caspases when stimulated by extracellular signals. Tumor necrosis factors (TNF) and TNF-related apoptosis inducing ligands (TRAIL or Apo2L) are cytokines (proteins secreted by immune cells) which bind to death factors and directly activate apoptosis. A ligand is an ion or molecule that can bind to another compound and form a complex molecule.
Several therapies including purified formulations of TRAIL cytokines and monoclonal antibodies that stimulate death receptors are in early phase of clinical trials.
Latest Cancer News
Daily Health News
Cancer cells grow and proliferate endlessly. Targeted therapy to stimulate cell death or apoptosis can help keep tumors in check. Normal cells have a finite cell cycle of growth, division and differentiation. The final stage in the cell cycle is apoptosis, or programmed cell death, when they are infected, old, damaged or simply no longer needed.
Multimedia: Slideshows, Images & Quizzes
Top 10 Cancers Quiz
Take this quiz to learn the causes of cancer. Get the facts about the causes, symptoms, and treatments for the world's most...
Skin Cancer Symptoms, Types, Images
Discover the causes, types, and treatments of skin cancer. Learn how to prevent skin cancer and how to check for melanoma, basal...
Cancer-Fighting Foods in Pictures: Resveratrol, Green Tea, and More
Experts have praised certain foods for their ability to reduce cancer risks. Learn which foods and eating strategies may help...
Signs of Cancer in Men: Could it Be Cancer?
See pictures of which 15 cancer symptoms men ignore such as skin changes, difficulty swallowing, rapid weight loss, a breast...
Signs of Cancer in Women: Symptoms You Can't Ignore
Cancer symptoms can surprise women if they don't know what to watch out for. 15 cancer symptoms women ignore such as weight loss,...
Understanding Cancer: Metastasis, Stages of Cancer, and More
Learn the basics about cancer including types, causes, how it spreads, symptoms and signs, stages and treatment options. Read...
Cancer: Guide to Leukemia
Learn about the common types and stages of leukemia, who gets it, symptoms, tests, treatments, and more. People with blood cancer...
Cancer: How to Lower and Cut Your Risk of Cancer
About a third of all cases of cancer can be prevented. Find out how to lower your chances of getting it.
Cancer: Cancer 'Remedies' That Don't Work
You may have read about an all-natural cure for cancer. While many therapies are helpful, some aren't worth your time or money....
Cancer: Does This Cause Cancer?
Everything gives you cancer, right? Not really. WebMD's slide show tells you about the research into cancer and cell phones,...
Related Disease Conditions
Second Source article from Government
Cancer Risk Factors
Though it's difficult to say why some people develop cancer while others don't, research shows that certain risk factors increase a person's odds of developing cancer. These risk factors include growing older, family history of cancer, diet, alcohol and tobacco use, and exposure to sunlight, ionizing radiation, certain chemicals, and some viruses and bacteria.
Cancer is a disease caused by an abnormal growth of cells, also called malignancy. It is a group of 100 different diseases, and is not contagious. Cancer can be treated through chemotherapy, a treatment of drugs that destroy cancer cells.
Certain behavioral, lifestyle, and environmental factors contribute to cancer. Cancer prevention involves modifying these factors to decrease cancer risk. Tobacco use, alcohol consumption, physical inactivity, inadequate fruit and vegetable intake, and obesity increase the risk of certain cancers. Vaccines, genetic testing, and cancer screening also play a role in cancer prevention.
Cancer pain results from the tumor pressing on nerves or invading bones or organs. Cancer treatments like chemotherapy, radiation, or surgery can also cause pain. Over-the-counter pain relievers, prescription medications, radiation, biofeedback, and relaxation techniques are just some treatments for cancer pain.
Cancer fatigue is a lack of energy that is caused by cancer or cancer treatment, including chemotherapy, radiation, biological therapy, or bone marrow transplantation. Strategies to combat cancer fatigue include scheduling rest, pacing oneself, planning ahead and prioritizing work and activities, eating the right foods, exercising, and practicing proper body mechanics.
Which Is the Deadliest Cancer?
Lung cancer is considered to be the most deadly cancer. More people die from lung cancer each year than from breast, colorectal and prostate cancer combined.
At What Stage of Cancer is Chemotherapy Used?
The decision to use chemotherapy may vary depending on the aggressiveness, stage and type of cancer. Usually, chemotherapy may be used for all stages in most cancer types. Chemotherapy is a type of medicine or combination of medications that is used to treat or kill cancer cells.
What Type of Cancer Makes You Very Tired?
Extreme and recurrent tiredness is one of the common symptoms of most types of cancers. Tiredness is usually considered a warning sign of cancer progressing. Tiredness related to cancers usually does not get better with adequate rest or sleep.
Treatment & Diagnosis
- Cancer FAQs
- Cancer,Stroke & Heart Attack Risks- ReducedThrough Walking
- Cigar Smoking ... Heart & Lung Disease & Cancer
- Cancer Care in the Elderly
- Chronic Viral Hepatitis, Alcoholism, Cirrhosis Linked to Liver Cancer
- Cancer Survivor?
- Complementary and Alternative Cancer Treatments
- 10 Cancer Symptoms That Men Ignore
- Cancer Prevention: The Anticancer Diet
Medications & Supplements
- Targeted Therapy: What Are The 10 Hallmarks of Cancer?
- Targeted Therapy: What Is Oncogenic Addiction in Cancer Cells?
- Targeted Therapy: What Are Invasion and Metastasis in cancer?
- Targeted Therapy: What Is Replicative Immortality in Cancer?
- Targeted Therapy: What Is the Function of A Tumor Suppressor Gene?
- Targeted Therapy: What Are Targeted Antiangiogenic Cancer Therapies?
Prevention & Wellness
- 15 Cancer Symptoms Men Ignore
- 15 Cancer Symptoms Women Ignore
- Cancer Prevention: Eat to Lower Your Cancer Risk
- Cancer-Fighting Foods
- Cancer Prevention: What Works?
- Cancer Causing Agents - Carcinogens
- Cancer Survivors: Earning a Living
- Cancer-Related Anemia: The Risks
- Cancer Again
- Cancer Risk: It's a Girl Thing
- Cancer Survival - Better & Longer Survival Rates
- Cancer, A Wound That Doesn't Heal
- Cancer Control Month
- Cancer Prevention and Garlic
- Cancer Prevention and Red Wine
- Cancer Prevention and Tea
- Cancer Facts, About Women
- Cancer Diagnoses & Deaths - Y2K Estimates
Health Solutions From Our Sponsors
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.