Personalized Cancer Care
Despite the advances in fighting cancer, the oncology field still reports the lowest treatment efficacy rate of any of the major medical therapeutic areas.
Cancer is a very complex disease. In fact, it is not one disease, but rather a broad group of various diseases, compounding the challenges of effective treatment and cure. This is all the more reason the medical community should utilize the tools available to them as effectively as possible.
Many of the recent breakthroughs in improving the effectiveness of cancer treatment have come from a “personalized medicine” approach. Personalized medicine is the tailoring of medical treatment to the individual characteristics of each patient rather than the “one-size-fits-all” approach of the past. Much of the focus in personalized medicine has been placed on understanding a person’s unique molecular and genetic profile. This pharmacogenomics information can be used to predict what makes them susceptible to cancer or to predict which medical treatments will be safe and effective for each patient and which ones will not be beneficial. These are remarkable and clinically significant advancements.
However, although pharmacogenomics can provide the patient’s genotype, it cannot present the patient’s phenotype to define the specific drug dosage necessary to achieve the desired optimal systemic blood concentration to provide the best therapeutic effect with minimal side effects. This is because many factors besides genetic regulation impact drug absorption and clearance. These include disease stage, organ function, age, race and drug-drug interactions, among others. These factors can result in interpatient drug blood level variability as high as 30-fold.
The current standard of care for chemotherapy drug dosing is Body Surface Area (BSA). BSA still represents the old “one size fits all” approach to patient care in this age of personalized medicine. This method of dosing, which takes into account only the patient’s height and weight, was derived in 1916 based upon the study of only eight patients as a means of estimating the conversion of drug doses in animals to human doses. However, there is no rigorous scientific basis for the use of BSA with cancer drugs. In fact, there is growing scientific evidence that this approach is invalid and results in high interpatient systemic drug exposure variability.
The only reliable way to identify a patient’s phenotype is by actually measuring the patient’s systemic drug concentration while they are receiving therapy. Since the 1970s, doctors have been using Therapeutic Dose Management (TDM) to measure plasma drug concentrations and individualize the dose for each patient to achieve the optimal therapeutic efficacy while reducing the risk of dangerous toxic side effects. Use of TDM has been the standard of care with transplantation, antiepileptic and antibiotic drugs for many years.
Chemotherapy drugs ideally fit the profile of agents that should be dose managed. Many studies have demonstrated a correlation of drug blood levels to biological effects (treatment efficacy and toxicity) and these drugs clearly present the risk of dose-limiting toxicity.
Until recently, testing patients’ chemotherapy blood levels entailed the use of slow, expensive and tedious methods, thereby making widespread clinical use of pharmacokinetic (PK) dose management impractical. With the availability of the new MyCare line of simple blood tests, fast and cost effective antineoplastic drug dose management is a personalized medicine reality.