Pharmacogenomics in gastrointestinal disorders

Current strategies to minimize toxicity of oxaliplatin: selection of pharmacogenomic panel tests

Oxaliplatin is an anticancer drug routinely used to treat colorectal, gastroesophageal, ovarian, breast, head/neck, and genitourinary cancers. Discontinuation of oxaliplatin treatment is mostly because of peripheral neuropathy, more often than for tumor progression, potentially compromising patient benefit. Several strategies to prevent neurotoxicity have so far been investigated. To overcome this life-threatening side effect, while taking advantage of the antineoplastic activities of oxaliplatin, we describe in detail recent findings on the underlying mechanisms of genetic variants associated with toxicity and resistance to oxaliplatin-based chemotherapy in colorectal cancer. A comprehensive panel of eight polymorphisms, previously validated as significant markers related to oxaliplatin toxicity, is proposed and discussed. In addition, the most common available strategies or methods to prevent/minimize the toxicity were described in detail. Moreover, an early outline evaluation of the genotyping costs and methods was taken in consideration. With the availability of individual pharmacogenomic profiles, the oncologists will have new means to make treatment decisions for their patients that maximize benefit and minimize toxicity. With this purpose in mind, the clinician and lab manager should cooperate to evaluate the advantages and limitations, in terms of costs and applicability, of the most appropriate pharmacogenomic tests for routine incorporation into clinical practice.

Pharmacogenomics: historical perspective and current status

Pharmacogenomics and its predecessor pharmacogenetics study the contribution of genetic factors to the interindividual variability in drug efficacy and safety. One of the major goals of pharmacogenomics is to tailor drugs to individuals based on their genetic makeup and molecular profile. From early findings in the 1950s uncovering inherited deficiencies in drug metabolism that explained drug-related adverse events, to nowadays genome-wide approaches assessing genetic variation in multiple genes, pharmacogenomics has come a long way. The evolution of pharmacogenomics has paralleled the evolution of genotyping technologies, the completion of the human genome sequencing and the HapMap project. Despite these advances, the implementation of pharmacogenomics in clinical practice has yet been limited. Here we present an overview of the history and current applications of pharmacogenomics in patient selection, dosing, and drug development with illustrative examples of these categories. Some of the challenges in the field and future perspectives are also presented.

Molecular predictive and prognostic markers in colon cancer

Colorectal cancer remains one of the major cancer related death despite progress in the cytotoxic treatment of colorectal cancer (CRC) over the past decade. The introduction of targeted agents has improved the progression free and overall survival of metastatic disease. However, 40-50% of patients do not experience beneficial effects and it remains a challenge to select patients likely to respond to therapy. Several new molecular predictive and prognostic markers have been identified and are now being translated into routine clinical practice. K-Ras mutation is the first established molecular marker with a lack of response in K-Ras mutated patients treated with an epidermal growth factor receptor (EGFR)-targeted therapy. The validation of predictive and prognostic markers will result in more successful and less toxic therapeutic regimens for cancer patients. This review aims to summarize the most important currently available predictive and prognostic molecular markers in colorectal cancer.

Pharmacogenomics and -genetics in colorectal cancer

Despite recent progress in our knowledge about the development and therapy of colorectal cancer (CRC), it still remains one of the major cancer related deaths throughout the world. With the introduction of new cytotoxic and targeting agents a significant improvement in progression-free and overall survival has been achieved. However, a significant percentage (40-50%) of patients do not experience beneficial effects and suffer from severe toxicities. It will be critical to identify molecular markers, which may help to assess therapeutic response and outcome in CRC. Validation of predictive and prognostic molecular markers will enable oncologists to tailor patient specific treatment strategies for the individual patient according to the molecular profile of both the patient and their tumor. Individualized therapy will help to improve therapeutic efficacy and to minimize toxicities and therapeutic expenses.