Phase I and pharmacodynamic trial of the DNA methyltransferase inhibitor decitabine and carboplatin in solid tumors.

PURPOSE: The DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (decitabine) induces DNA demethylation and re-expression of epigenetically silenced genes, and increases carboplatin sensitivity of tumor xenograft models. We designed a clinical study to determine the feasibility of delivering a dose of decitabine, combined with carboplatin, that would be capable of producing equivalent biologic effects in patients with solid tumors. PATIENTS AND METHODS: In a two-stage design, 33 patients received escalating doses of decitabine administered as a 6-hour infusion on day 1 followed by carboplatin, area under the concentration-time curve (AUC) 5 (cohort 1) and AUC 6 (cohort 2), on day 8 of a 28-day cycle. Pharmacodynamic analyses included 5-methyl-2'-deoxycytidine levels, MAGE1A CpG island methylation, and fetal hemoglobin (HbF) expression. RESULTS: The major toxicity was myelosuppression. Dose limiting toxicities, prolonged grade 4 neutropenia (one patient), and sepsis and grade 3 anorexia/fatigue (one patient), were seen in two of four patients treated with decitabine 135 mg/m2 and carboplatin AUC 5. Dose limiting toxicity comprising neutropenic sepsis (one patient) and grade 3 fatigue (one patient) was seen in two of 10 patients treated at decitabine 90 mg/m2 and carboplatin AUC 6. Decitabine induced dose-dependent, reversible demethylation in peripheral-blood cells (PBCs) maximally at day 10. Furthermore, decitabine 90 mg/m2 induced demethylation of the MAGE1A CpG island in PBCs, buccal cells, and tumor biopsies, as well as elevation of HbF expression. CONCLUSION: Decitabine can be combined safely with carboplatin at a dose and schedule that causes epigenetic changes equivalent to or greater than that observed in mice with carboplatin-sensitized xenografts. The recommended dose/schedule for phase II trials is decitabine 90 mg/m2 (day 1) followed by carboplatin AUC 6 (day 8) every 28 days.

Development of a bacteriophage model system to investigate virus inactivation methods used in the treatment of bone allografts.

Bone allografts are commonly used in a variety of surgical procedures, to reconstruct lost bone stock and to provide mechanical support during the healing process. Due to concerns regarding the possibility of disease transmission from donor to recipient, and of contamination of grafts during retrieval and processing procedures, it is common practice to sterilise bone allografts prior to issue for clinical use. It is vital that the sterilisation processes applied to allografts are validated to demonstrate that they achieve the required level of bioburden reduction, and by extension that validated models are used for these studies. Two common sterilisation protocols applied to bone allografts are gamma irradiation and ethylene oxide gas sterilisation, and there are currently no validated models available for measuring the anti-viral efficacy of ethylene oxide treatment with regard to bone allografts or readily useable models for assessing the anti-viral efficiency of gamma irradiation treatment. We have developed and validated models for both these sterilisation processes, using the bacteriophage varphix174, and utilised the models to measure the antiviral activity of the standard ethylene oxide and gamma irradiation sterilisation processes applied to bone allografts by the National Blood Service. For the irradiation model, we also utilised bacterial spores (Bacillus pumilus). Our results show that ethylene oxide sterilisation (which can only be applied to lyophilised grafts) inactivated > 6.1 log(10) of the model virus, and gamma irradiation (at 25 -40 kGy and applied to frozen allografts) inactivated 3.6 - 4.0 log(10) of the model virus and > 4 log(10) of the bacterial spores. Gamma irradiation at this dosage is therefore not in itself a sterilisation process with respect to viruses.