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Purpose In tumours with wild-type TP53, the tumour-suppressive function of p53 is frequently inhibited by HDM2. This phase I, dose-escalating study investigated the maximum tolerated dose (MTD), safety, pharmacokinetics and pharmacodynamics of SAR405838, an HDM2 inhibitor, in patients with advanced solid tumours ( NCT01636479 ). Methods In dose escalation, patients with any locally advanced/metastatic solid tumour with TP53 mutation prevalence below 40%, or documented as TP53 wild-type, were eligible. In the MTD expansion cohort, only patients with de-differentiated liposarcoma were included. Primary end-points were MTD and efficacy in the MTD expansion cohort. Secondary end-points included safety, pharmacokinetics and pharmacodynamics biomarkers. Results Seventy-four patients were treated with SAR405838 (50–800 mg once daily [QD], 800–1800 mg weekly and 1800 mg twice weekly). Two patients treated with SAR405838 400 mg QD had thrombocytopaenia as a dose-limiting toxicity (DLT). The MTD for the QD schedule of SAR405838 was 300 mg QD. No DLTs were observed with the weekly schedule; one patient had a DLT of nausea with the 1800 mg twice-weekly dose. Treatment with SAR405838 was associated with increased plasma MIC-1, reflecting p53 pathway activation. In the de-differentiated liposarcoma MTD cohort, 89% of the patients had HDM2 amplification at baseline and no TP53 mutations were observed; best response was stable disease in 56% and progression-free rate at 3 months was 32%. Conclusion SAR405838 had an acceptable safety profile with limited activity in patients with advanced solid tumours. The MTD of SAR405838 was 300 mg QD; MTD was not reached with the weekly schedule.

In the treatment of advanced colorectal cancer, irinotecan has become one of the most important drugs, despite its sometimes unpredictable adverse effects. To understand why some patients experience severe adverse effects (diarrhea and neutropenia), while others do not, the metabolic pathways of this drug have to be unraveled in detail. Individual variation in expression of several phase I and phase II metabolizing enzymes and ABC-transporters involved in irinotecan metabolism and excretion, at least partly explains the observed pharmacokinetic interpatient variability. Although the difference in expression-level of these proteins to a certain amount is explained by physiologic and environmental factors, the presence of specific genetic determinants also does influence their expression and function. In this review, the role of genetic polymorphisms in the main enzyme-systems (carboxylesterase, cytochrome P450 3A, and uridine diphosphate-glucuronosyltransferase) and ABC-transporters (ABCB1, ABCC2, and ABCG2) involved in irinotecan metabolism, are discussed. Since at this moment the field of pharmacogenetics and pharmacogenomics is rapidly expanding and simultaneously more rapid and cost-effective screening methods are emerging, a wealth of future data is expected to enrich our knowledge of the genetic basis of irinotecan metabolism. Eventually, this may help to truly individualize the dosing of this (and other) anti-cancer agent(s), using a personal genetic profile of the most relevant enzymes for every patient.

Over recent years, several non-oncological agents were removed from the market based on cardiac toxicity due to prolongation of the cardiac repolarisation, defined as prolongation of the QTc interval on the ECG, observed post registration. This resulted in enhanced regulatory attention on cardiac safety monitoring during drug development and, in May 2005, the implementation by the FDA of the E14 ‘Clinical evaluation of QT/QTC interval prolongation and proarrhythmic potential for non-antiarrhythmic drugs’. These guidelines have been written in the light of drug development in non-oncological areas and do not take into consideration the differences in the patient population, in study design or the risk-benefit balancing relative to potential QT-liability and potential anticancer efficacy. During the development of new drugs a continuous benefit and risk assessment takes place. The involved considerations will be different and dependent on the patient population targeted. In oncology the nature and severity of the disease is such that most patients with metastatic disease will still succumb to their disease. Balancing the need for novel treatment in this area against the risks of the medical products will result in accepting more toxicity compared to other indications, as is presently the case for many standard therapeutic options in oncology. Also, the intense lobbying of patient representatives for early access to experimental drugs indicates the willingness of this patient