Sunday, December 29, 2019

Targeted vs standard chemotherapy


Sources: National Cancer Institute, American Cancer Society, Science Daily, Web MD

Targeted cancer therapies are drugs or other substances that block the growth and spread of cancer by interfering with specific molecules that are involved in the growth and spread of cancer. 

Targeted therapies differ from standard chemotherapy  in several ways:
  • Targeted therapies act on specific molecular targets that are associated with cancer, whereas most standard chemotherapies act on all rapidly dividing normal and cancerous cells.
  • Targeted therapies are deliberately chosen or designed to interact with their target, whereas many standard chemotherapies were identified because they kill cells. 
  • Targeted therapies often block tumor growth, whereas standard chemotherapy agents kill tumor cells.

Targeted therapies are currently the focus of much anticancer drug development. They are a cornerstone of precision medicine, a form of medicine that uses information about a person’s genes and proteins to prevent, diagnose, and treat disease.

Many targeted cancer therapies have been approved by the Food and Drug Administration (FDA) to treat specific types of cancer. Others are being studied in clinical trials (research studies with people), and many more are in preclinical testing (research studies with animals). Read more.

History of Targeted Therapy
Targeted therapy was first used in the 1940s when iodine was used to kill thyroid cancer cells. Tamoxifen, first developed in 1970s as a contraceptive,  was found to bind to estrogen receptors in breast tissue. Some breast cancer cells require estrogen to grow and  tamoxifen can prevent recurrence of estrogen receptor-positive breast cancer for pre- and post-menopausal women. 

In the past two decades, the discovery of oncogenes and tumor suppressor genes, and the completion of human genome sequencing fueled some major advances in the understanding of the molecular mechanisms leading to cancer. Subsequently, such newly emerging biological and genetic information rapidly prompted the introduction of a large number of new targeted cancer therapies.

Types of Targeted Therapies:                                      
There are two main types of targeted therapies: small molecule medicines and monoclonal antibodies.

Small molecule medicines are small enough to slip inside cancer cells and destroy them. Small molecule meds treat cancer by blocking signals that tell tumor cells to grow and are usually administered in pill form.

Monoclonal antibodies are too big to get into cells. Instead, they attack targets on the outside of cells or right around them. Sometimes they're used to launch chemo and radiation straight into tumors. They are usually administered through an IV in a vein in the arm at a hospital or clinic. Sometimes they are given as a shot.

Scientists have come up with many small molecule meds and monoclonal antibodies that make use of different targets to treat cancer in different ways. Varieties of therapies include: hormone therapies, signal transduction inhibitors, gene expression modulators, apoptosis (natural cell death) inducers, angiogenesis (growth of new blood vessels feeding tumors) inhibitors and immunotherapies. Read more.

Latest targeted therapy news . . .

More targeted, less toxic:. The golden future of cancer treatment: New synthetic molecules are up to 24 times more effective at killing cancer cells than a widely-used cancer drug and they're built with resistance-fighting features to keep them effective over time, unlike current chemotherapies. Pre-clinical studies show the molecules are promising candidates for development into a new class of gold-based drugs that can wipe out the cancer without destroying healthy cells. Read more. 

Clues to improve cancer immunotherapy revealed.
Helper T cells appear vital to more robust anti-tumor response. Cancer immunotherapy drugs trigger the body's immune system to attack tumors and have revolutionized the treatment of certain cancers, such as lymphoma, lung cancer and melanoma. Yet, while some patients respond well to the drugs, others don't respond at all. Cancer immunologists want to change that.

A new study by researchers at Washington University School of Medicine in St. Louis indicates a way for cancer immunotherapy to spur a more robust immune response. Such knowledge could lead to the development of better cancer vaccines and more effective immunotherapy drugs called checkpoint inhibitors. The study is published Oct. 23 in the journal Nature. Read more.

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