We often hear of Precision Medicine for Cancer, but what is Precision Medicine? How is it different from standard treatment protocols? What can be the benefits of choosing Precision Medication over standard protocols?
The diagnosis and treatment of cancer at a cellular or molecular level is known as Precision Medicine.
Cancer is a heterogeneous disease, with a different genetic profile not only between patients with different cancers but also differences in genetic, molecular and cellular profile even within the same type of cancer.
All cancers are genetic by nature and with cellular profile changing over time even in the same patient, till now no single drug is known to cure even a single type of cancer let alone different types of cancers.
Standard chemotherapy protocols focus on administering standard chemotherapy drugs ( one size fits all) without taking into account the cellular or genetic profile of the patient. Tumor markers, genetic profile plays an important role in cancer treatment.
Precision medicine, on the other hand, focuses on accurate and effective treatment to each patient based on the genetic profile, the proteins feeding the tumors or the cancers.
There are a sufficient number of detractors even amongst the best doctors but precision medicine or administering drugs based not a specifically tailored patient profile not being the best option is a premature conclusion.
Let’s shed some light on Precision medicine for breast cancer.
Breast cancer treatment in India and in most countries, beyond surgical options of lumpectomy, a mastectomy involves administering chemotherapy and radiotherapy, with chemotherapy being the first line of treatment.
The difference in outcomes depends upon whether the patient has been tested for HER2(human epidermal growth factor receptor 2), ER, PR or not.
For patients testing positive for HER 2, the addition of trastuzumab or Herceptin to chemotherapy slows down disease progression. Lapatinib plus chemotherapy (i.e., capecitabine) achieved a longer median time to disease progression compared with chemotherapy alone.
A combination of pertuzumab, trastuzumab, and chemotherapy further improved the median overall survival time to a median of almost 5 years compared with a combination of only trastuzumab and chemotherapy for a median of 3 and half years.
Similarly treatment with ado-trastuzumab emtansine, a conjugate of a HER2 monoclonal antibody and a cytotoxic drug, significantly improved the length of progression-free survival and overall survival with lower adverse effects when compared with lapatinib and chemotherapy
The above examples clearly show how genetic profiling, identification of key mutations like the Bcr-Ablfusion or HER2 can benefit a large number of breast cancer patients.
Genetic profiling also enables the identification of molecular targets for intervention. Cell death is caused by a combination of deficiencies in the expression of two or more genes, whereas deficiency in only one of these genes can increase viability or enhance the multiplication of mutant cells. For example, BRCA (mutant gene responsible for particularly aggressive breast cancers( and poly ADP ribose polymerase (PARP) genes were found to have a synthetic lethal relationship.
By using olaparib, a PARP inhibitor, to treat BRCA-mutant ovarian cancer patients, the progression-free survival of BRCA-mutant ovarian cancer patients was significantly prolonged by olaparib compared with standard chemotherapy protocols.
This methodology focusses on identifying cancer vulnerabilities and subsequent tailored cancer treatment based on the patient profile.