Role of Targeted Therapy in Breast Cancer Treatment

Role of Targeted Therapy in Breast Cancer Treatment

Targeted Therapy in Breast Cancer Treatment

Introduction

Breast cancer is the most common type of cancer in women and affects more than 2 million women every year the world over. This disease is one in which the breast tissue develops a precancerous condition where cells grow and spread differently than they should, and is not limited to any particular age or gender. Because the human body is in a constant state of development and the studies and technologies in this area have developed for years, methods of diagnosing and treating breast cancer have improved.

The last key advance around which the past few decades revolve is the impetus of molecular targeted therapy as a wholly different method of tackling cancer, targeting cancer cells at the level of their molecules and changes in genetic makeup.

Role of Targeted Therapy in Breast Cancer Treatment
Credit: compassoncology

Basic Ideas of Targeted Therapy

It is also referred to as targeted (or molecularly targeted) therapy or precision therapy, which involves a drug or other intervention that first attacks cancer cells without damaging healthy cells. While conventional chemotherapy tends to be fairly toxic and indiscriminate in its killing, targeted therapy is more spared in this regard. It aims to use specific properties or characteristics of cancer cells to prevent their development and growth.

Targeted therapy is about going beyond the concept that cancer cells are inherently different than normal cells, and figuring out that they have unique molecular characteristics that make them different from normal cells. Specifically, the cancer cell’s molecular markers indicate how scientists can design drugs that can specifically attack cancer cells but not normal cells. It can improve drug compliance with treatment, decrease the toxicity associated with therapy, and reduce the likelihood of drug resistance mechanisms developing.

Role of Targeted Therapy in Breast Cancer Treatment
Credit: nationalbreastcancer

Targeted therapy component in the treatment of breast cancer

Breast cancer is a complex disease that is explainable by various genetic differences and molecular signatures. Therefore, it is obvious that one effective treatment method will not work for all patients. With analytic technologies in genomics and proteomics reaching breakthroughs, we have entered the age of breast cancer biomarker research and their respective pathways. This information has helped in the establishment of therapies that can pinpoint these molecular changes and therefore act as a breakthrough in the enhancement of the breast cancer cure.

Targeting in breast cancer has several benefits over the traditional chemotherapy. Firstly, it can provide a targeted therapy that compared to the traditional methods will be more efficient due to the possibility for doctors to address the therapy to definite molecular types of cancer. Second, it may also be noted that the target therapies exhibit relatively low side effects, usually observed in chemotherapy treatments. In other cases, targeted therapies can be given alongside other therapies including chemotherapy, radiation, and immunotherapy to increase the likelihood of their success.

Breast cancer molecular signaling and biomarkers

Breast cancer is complex and can be described by multiple molecular profiles and indicators of this process. Some of the key pathways and markers that are targeted in breast cancer treatment include:

  • HER2 – The HER2 protein is overexpressed in about 15% to 20% of Breast cancer patients. In some cases, this overexpression leads to a continual activation of the HER2 signaling pathway that helps cancer cells to grow and live. A few drugs act directly on the HER2 protein, such as trastuzumab (Herceptin), pertuzumab (Perjeta), and lapatinib (Tykerb).
  • Estrogen Receptor (ER) and Progesterone Receptor (PR) – It is established that most of the BCs are hormone receptor-positive, hence, they overexpress either the estrogen receptor or the progesterone receptor. These receptors stimulate cancer cell proliferation in the presence of hormones, estrogen and progesterone. These target drugs like anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin) prevent the aromatase enzyme from making estrogens or blocking estrogen from attaching to cancer cells.
  • Genetic changes – Recent development in the molecular analysis of the disease has provided an understanding of genetic changes that cause breast cancer for example mutations of the PI3K/AKT/mTOR and MAPK signal transduction pathways. The basis for these targeted therapies consists of these specific genetic aberrations including PI3K inhibitors such as idelalisib, mTOR inhibitors like everolimus, and BRAF inhibitors like vemurafenib.
  • Breast cancer microenvironment – This comprises cancer cells, the adjacent fibroblasts, immune cells, and blood vessels, which are essential in breast cancer progression. Bevacizumab which are angiogenic inhibitors, pembrolizumab, and imtazolizumab are immune checkpoint inhibitors that target the tumor microenvironment and tumor cell size and growth.

Categories of Targeted Therapy in Breast Cancer

As mentioned earlier, many of these targeted therapies were developed that target these molecular pathways and markers. Some of the key classes include:

  1. These are monoclonal antibodies which are lab-made antibodies that copy and mimic what the immune system does to attack cancer cells. Examples of mAbs that have been put to use in the treatment of BC include trastuzumab (Herceptin) and HER2 antigen; pertuzumab (Perjeta) and HER2 receptor; and bevacizumab (Avastin) and VEGF or angiogenies.
  2. Small Molecule Inhibitors are small organic molecules that can interact with target proteins or enzymes of the cancer cells to inhibit them. Breast cancer treatment small molecule inhibitors include HER2/EGFR signaling inhibitors (lapatinib [Tykerb] and neratinib [Nerlynx]) and CDK4/6 signaling inhibitors (palbociclib [Ibrance] and ribociclib [Kisqali]).
  3. Targeted therapies are therapies directed at hormones (e.g. hormone therapies to prevent effects of estrogen or lower estrogen production in hormone receptor-positive breast cancer). Such hormone therapies include aromatase inhibitors: anastrozole, letrozole, exemestane; selective estrogen receptor downregulators: fulvestrant.
  4. Molecular therapies that exploit the body’s immune response to find and kill cancer cells are called immunotherapies. Cancer vaccines like sipuleucel-T that strengthen the immunologic response to cancer and some of the immunotherapies that may be used in the treatment of breast cancer like immune checkpoint inhibitors such as pembrolizumab, atezolizumab, and avelumab, which consist of an inhibition of immune checkpoints proteins.

Targeted therapies mean treatment being delivered specifically to the cancer cells and selecting cancer treatments that have the least effect on the rest of the body simply because it is being attacked by cancer cells.

In the past few years, targeted therapies have led to the lengthy of fresh hope for a myriad of breast cancer sufferers by availing better treatment regimens and outcomes as well as minimal side effects. Nevertheless, we also want to point out that these therapies possess some inherent limitations as well.

Role of Targeted Therapy in Breast Cancer Treatment
Credit: https://www.nationalbreastcancer.org/

Benefits

  1. Personalized Treatment: Targeted therapies allow treating breast cancer individually – depending on the molecular type of cancer in a patient.
  2. Targeted Therapies Are More Efficient: In most cases, targeted therapies are more efficient than conventional treatments such as chemotherapy and leave the patient with a greater survival rate than the general population.
  3. Fewer Side Effects: Many targeted therapies work only on cancer cells and therefore cause fewer side effects than traditional chemotherapy.

Limitations

  1. It has learnt that not all breast cancers possess the same molecular characteristics or genetic profiles and only treatments that capture a particular patient’s cell profile work.
  2. Common in cancer cells is the fact that they develop resistance to targeted therapy within some time, leading to treatment failure and disease progression.
  3. Targeted therapy has high costs in that the revenue from developing and commercializing brands might not be affordable to many of them let alone chronic patients living in low and middle-income countries.

Conclusion

As a means of giving new ways to patients with such illnesses, targeted therapy has been important in the treatment of breast cancer. With the current state of how we know of the molecular mechanisms and biomarkers that lead to the development and progression of breast cancer not being completely understood, one would imagine that this list will only grow and more targeted treatments in the future will become more and more refined.

In particular, researchers are now investigating the use of ‘combination drugs’ where two or more drugs are given to kill the cancer cells at the same time and target different molecules within those cells. This is expected to increase the effectiveness of treatment and decrease the chances of drug resistance.

At the same time, precision medicine that uses a patient’s genotype and molecular characteristics to make treatment options is expected to greatly influence the approach to breast cancer in the future. Using genomic and proteomic data in addition to clinical data, the doctors working on the case can create very specific treatments that would give optimal therapeutic results in terms of effectiveness as well as harmful effects.

However, while these are promising pieces of news, targeted therapies aren’t a cure for breast cancer and there are some issues including limited availability, extreme costs, and drug resistance with targeted therapy for breast cancer. As a result, researchers, clinicians, and policymakers must expend more effort to tackle these challenges and ensure that patients diagnosed with breast cancer are offered the best and most innovative treatment at all times regardless of their economic status.

So in sum, targeted therapy has been shown to provide an important contribution in breast cancer treatment, providing new hope in improving the treatment of breast cancer and increasing the quality of life of patients. For this reason, and with our current developing knowledge of the molecular mechanisms of this multifaceted

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