A multicentre randomised phase II study of carboplatin in combination with gemcitabine at standard rate or fixed dose rate infusion in patients with advanced stage non-small-cell lung cancer

BACKGROUND

Intracellular gemcitabine triphosphate (dFdCTP) levels can be optimised by administering gemcitabine at a fixed dose rate infusion.

PATIENTS AND METHODS

Patients with chemonaive advanced non-small cell lung cancer (NSCLC) were randomised to receive gemcitabine at a fixed dose rate gemcitabine 750 mg/m(2) over 75 min (arm A) or gemcitabine 1000 mg/m(2) over 30 min (arm B) on days 1 and 8 every three week cycle. Carboplatin at AUC of 5 was administered in both treatment arms on day 1 of each cycle. End points were activity, tolerability and pharmacokinetics of plasma and intracellular gemcitabine.

RESULTS

76 patients were randomised. Response rate was 34% in arm A and 42% in arm B. Toxicity and quality of life scores were similar for both treatment arms. Mean plasma Cmax(gemcitabine) and mean dFdCTP AUC in arm A was 20.8 microM +/- 17.2 microM and 35,079 +/- 18,216 microM*min respectively and in arm B, 41.2 +/- 13.9 microM and 32 249 +/- 11 267 microM*min respectively. dFdCTP saturation was reached in Arm B but not in Arm A.

CONCLUSION

The saturability of dFdCTP accumulation in Arm A suggests optimal delivery of gemcitabine is achieved using fixed rate infusion compared to 30-min infusion. Fixed dose rate gemcitabine is active and feasible, supporting the concept of fixed dosing rate of gemcitabine in advanced NSCLC. However, this entails a longer infusion time with associated higher costs involved.

Analysis of gemcitabine pathway genotypes in ethnic Asians and their relationship with outcome in non-small cell lung cancer (NSCLC) patients

2008

Background: Genotypic variation for drug metabolising enzymes, targets and transporters is associated with inter-patient and inter-ethnic variability in toxicity and efficacy. Gemcitabine is a nucleoside anti-metabolite used in a range of solid tumors. Aims: 1) to determine genotype distribution of genes involved in gemcitabine pharmacology pathway in ethnic groups; 2) to evaluate the association between genotypes and treatment related outcomes in patients with chemo-naive, advanced NSCLC receiving gemcitabine based chemotherapy on a prospective study. Methods: Candidate genes involved in gemcitabine pharmacology were identified from a comprehensive search of public databases (NCBI, PharmGKB), and publications. 25 variants of 9 candidate genes (RRM-1, SLC28A1, SLC28A2, SLC28A3, SLC29A2, POLA2, DCTD, CDA, TS) were genotyped from blood in 94 healthy donors and 76 cancer patients (breast 22, NSCLC 54) with pyrosequencing. Chi-squared, Kruskall-Wallis, and Kaplan-Meier analysis were used to evaluate associations between genotypes and ethnic groups and clinical end points. Results: Significant differences in genotype distribution between Chinese, Malay and Indian were seen in 5/25 loci (see table ). In NSCLC patients, POLA2 2089 (G > A) was associated with neutropenia (p = 0.022), SLC28A1-1576 (C > T) with neutropenia nadir (p = 0.030) and thrombocytopenia nadir (p = 0.037), RRM-1 -524 (T > C) with neutropenia (p = 0.024) and SLC28A2–283 (CA 18.3 vs CC 8.5 months, p = 0.004), and SLC28A2–22 (CC 8.0 vs CT 18.3 months, p = 0.002) with survival. Conclusions: Our results suggest there is significant genotypic variability among ethnic groups. Variants in gemcitabine transporters and targets may be useful indicators of gemcitabine related toxicity and survival. Further studies should be performed to confirm these preliminary findings.

[Table: see text]

No significant financial relationships to disclose.