Feasibility of a prospective host cell reactivation assay (HCRA) in non-small cell lung cancer (NSCLC) patients.

Abstract

10586 Background: DNA repair capacity (DRC)—the ability to repair BPDE-induced DNA adducts—measured in peripheral blood lymphocytes (PBLs) by the HCRA has been shown to correlate with survival in patients (p) treated with cisplatin-based chemotherapy. p with high DRC had significantly shorter survival (Bosken et al. JNCI 2002). However, the HCRA of DRC has not been tested prospectively. Methods: Cryopreserved PBLs from 41 NSCLC p were cultured for 96 hours under phytohaemagglutinin stimulation. The pmaxGFP plasmid was nucleoporated in the cells of the host under two different experimental conditions: (i) undamaged (GFP-UND) and (ii) 254nm UV light-damaged plasmid DNA (1,000 J/m2) (GFP-DAM). After transfection, the cells were incubated for 24 hours in culture media to allow, firstly, repair of UV-damaged plasmids, and secondly, reexpression of the GFP reporter protein. By flow cytometry, the dead cells (positively stained with propidium iodide) were excluded and DRC was calculated in alive cells as follows: percentage DRC = (pmaxGFP-DAM/pmaxGFP-UND) * 100, where pmaxGFP-DAM and pmaxGFP-UND correspond to the percentage of alive cells positive for GFP protein. Results: There were no differences in DRC according to gender, season of the year or histology. Median DRC was 8.77 for p with PS 0, 10.49 for p with PS 1, and 21.60 for p with PS 2 (p=0.009). p treated with chemotherapy, with or without surgery and/or radiotherapy, had a higher relative risk (RR) of death associated with increased DRC (p=0.07) (Table). Conclusions: HCRA measured in PBLs is feasible and can be useful in monitoring NSCLC p. Serial measurements to detect increments in DRC can provide a marker of acquired resistance to cisplatin-based chemotherapy. The correlation of DRC with the expression of DNA repair genes in the tumor should be investigated. Cox proportional hazards model of the RR of death associated with increased DRC Unadjusted RR (95%CI) 0.82 (0.66-1.02) p=0.07 Adjusted* RR (95%CI) (for age, sex, cigarettes/day, stage) 0.81 (0.65-1.02) p=0.07 No significant financial relationships to disclose.