Irinotecan toxicity during treatment of metastatic colorectal cancer: focus on pharmacogenomics and personalized medicine.

Colorectal cancer, one of the most frequent types of cancer worldwide, has a high mortality rate. Irinotecan (CPT-11) has been approved for the treatment of advanced or metastatic disease either as a single agent or, more commonly, as part of combined chemotherapeutic regimens. Treatment with irinotecan is often accompanied by severe toxicity (e.g. neutropenia and diarrhea) that can result in treatment interruption or cessation, thus jeopardizing the patient's prognosis and quality of life. Irinotecan is bioactivated into its metabolite SN-38, which is subsequently detoxified by uridine diphosphate-glucuronosyl transferases (mainly UGT1A1). Further, ABC transporters (i.e. ABCB1, ABCC1-ABCC6, and ABCG2) are responsible for drug efflux into bile and urine whereas OATP transporters (SLCO1B1) enable its influx from blood into hepatocytes. Genetic polymorphisms in these enzymes/pumps may result in increased systemic SN-38 level, directly correlating with toxicity. Contemporary research is focused on the clinical implementation of genetic screenings for validated gene variations prior to treatment onset, allowing tailored individual doses or treatment regimens.

Dermatomyositis with anti-TIF-1γ antibodies as a presenting symptom of underlying triple-negative breast cancer: a case report.

BACKGROUND: Dermatomyositis is an autoimmune myopathy characterized by proximal muscle weakness, muscle inflammation, and typical skin findings. It is a rare disease with an incidence of ~1/100 000. About 15-30 % of adult-onset cases are caused by underlying malignancy and dermatomyositis can be the first symptom of undiagnosed cancer, mainly in the case of anti-transcription intermediary factor 1γ (anti-TIF-1γ) antibodies presence. TIF-1γ is a transcriptional cofactor which is implicated in TGFß signaling pathway that controls cell proliferation, differentiation, apoptosis, and tumorigenesis. Its expression was shown to be associated with younger age, higher tumor grade, more estrogen receptor negativity, tumors larger than 2 cm, and tendency towards poor outcome in early breast cancer. No association between anti-TIF-1γ antibodies and prognosis has been proposed yet. CASE PRESENTATION: We report a case of a 43-year-old premenopausal woman presenting with the symptoms of systemic rheumatic disease, the most prominent being a typical skin rash and muscle pain. After a series of investigations, the patient was diagnosed with anti-TIF-1γ positive dermatomyositis and concurrent triple-negative breast cancer (cT1c N3c M0) as an underlying cause. Immediate intravenous corticosteroid therapy relieved the symptoms and enabled anticancer therapy to be commenced. Considering the tumor stage, neoadjuvant therapy with 4 courses of AC (Doxorubicin/Cyclophosphamide) followed by 4 courses of Paclitaxel/Carboplatin was administered. However, no tumor regression was documented and radiotherapy was chosen as the definitive treatment. CONCLUSION: Early detection of anti-TIF-1γ autoantibodies can contribute to a rapid diagnosis of tumor-associated dermatomyositis and enable immediate anticancer treatment. We demonstrate the emerging role of anti-TIF-1γ antibodies in the diagnostics of tumor-associated dermatomyositis. Furthermore, we propose a potential role of anti-TIF-1γ antibodies as a prognostic marker in early breast cancer patients.

Predictors of irinotecan toxicity and efficacy in treatment of metastatic colorectal cancer.

The colorectal cancer ranks high among the malignant tumours in incidence and mortality and irinotecan is standardly used in palliative treatment of metastatic disease in every therapeutic line. Unfortunately, the treatment with irinotecan is often associated with severe toxicities, especially neutropenia and diarrhea. The majority of the toxic manifestation is caused by the insufficient deactivation (glucuronidation) of irinotecan active metabolite SN-38 by UGT1A enzyme. The elevated SN-38 plasma concentration is responsible for the hematological and gastrointestinal toxicity that can become life-threatening. The patients carrying the mutation of the gene encoding UGT1A enzyme lack the ability of bilirubin glucuronidation, and suffer from the inherited un-conjugated hyperbilirubinemia (Gilbert syndrome, Crigler-Najjar type 1 and 2 syndrome). The mutations in other enzyme systems also play role in the etiopathogenesis of the irinotecan toxicity: CYP3A (cytochrome P-450), ABC family of transmembrane transporters (adenosine-triphosphate binding cassette). The goal of the contemporary research is to determine the predictive factors that will enable the individual adjustment of the individual drug dosage while minimising the adverse effects and maintaining the treatment benefit.