Demonstration of differences in drug resistance by direct testing of DNA excision repair activity following standard and liposomal daunorubicin exposure in normal paediatric marrow using high resolution CLSM

Predicting efficacies of anticancer drugs using single cell HaloChip assay

Single cell HaloChip assay can be used to assess DNA repair ability.

Relationship between DNA repair capacity and resistance to genotoxins in four human cell lines

We have developed fast, reliable and simple fluorescent method to assess and compare repair capacity of cells. To this end plasmid pEGFP containing the gene for the enhanced green fluorescent protein was damaged in vitro by genotoxic agents and introduced into cells by transfection. The repair capacity of the cells was determined from the number of fluorescent cells counted with a fluorescent microscope 24 h after transfection. The ability of four human tumor cell lines--HEK293, HeLa, Namalwa and K562 to repair DNA lesions inflicted by cis-diamminedichloroplatinum(II), UV light, 8-methoxypsoralen and 4',5'-8-trimethylpsoralen were determined and compared to the survival rates of the cells after treatment with the same genotoxic agents. In most but not all cases, there was a good correlation between repair capacity and cell survival. This finding indicates that the DNA repair capacity could be used as a biomarker in risk assessment and/or drug resistance assays.

Liposomal daunorubicin (DaunoXome) plus dexamethasone for patients with multiple myeloma. A phase II International Oncology Study Group study

BACKGROUND

Liposomal daunorubicin is an effective cytotoxic agent in patients with Kaposi sarcoma and hematologic malignancies. Anthracycline-based chemotherapy regimens, such as vincristine/doxorubicin/dexamethasone (VAD), are standard in the treatment of patients with multiple myeloma (MM). Cardiotoxicity remains a limiting factor in dose escalation of anthracyclines, and multidrug resistance (MDR) develops rapidly on exposure to anthracyclines. Liposomal daunorubicin was designed in an attempt to overcome MDR and to reduce anthracycline-related toxicities. Thus, an open-label, Phase II clinical study was conducted by the International Oncology Study Group to assess the efficacy and safety of intravenous liposomal daunorubicin at a dose of 100 mg/m2 given every 3 weeks for a maximum of 6 cycles in patients with recently diagnosed MM (n = 4 patients) or recurrent/refractory MM (n = 37 patients).

METHODS

Liposomal daunorubicin was administered as a single agent for the initial two cycles of therapy, and dexamethasone was added to all subsequent cycles. The primary study end point was response rates. Thirty-eight patients were treated, 35 of whom were evaluable for response.

RESULTS

A partial response was achieved in six patients (17%), including one patient with disease that previously was refractory to VAD therapy. Stable disease was observed in 22 patients (63%). The principal toxicity was myelosuppression. Grade 3 or 4 hematologic toxicities included granulocytopenia (26%), anemia (Grade 3 only; 11%), thrombocytopenia (11%), and febrile neutropenia (13%). The median survival in 35 patients with recurrent disease was 7.6 months.

CONCLUSIONS

Liposomal daunorubicin had activity in this population of poor-risk patients that was comparable to the activity of standard regimens. Further studies of this agent in combination with other anti-MM agents are warranted.