Evaluation of 5-fluorouracil pharmacokinetics in cancer patients with a c.1905+1G>A mutation in DPYD by means of a Bayesian limited sampling strategy.

BACKGROUND AND OBJECTIVE: Dihydropyrimidine dehydrogenase (DPD) is the initial enzyme in the catabolism of 5-fluorouracil (5FU) and DPD deficiency is an important pharmacogenetic syndrome. So far, only very limited information is available regarding the pharmacokinetics of 5FU in patients with a (partial) DPD deficiency and no limited sampling models have been developed taking into account the non-linear pharmacokinetic behaviour of 5FU. The aim of this study was to evaluate the pharmacokinetics of 5FU and to develop a limited sampling strategy to detect decreased 5FU elimination in patients with a c.1905+1G>A-related DPD deficiency. METHODS: Thirty patients, heterozygous for the c.1905+1G>A mutation in DPYD, and 18 control patients received a dose of 5FU 300 mg/m2 and/or 5FU 450 mg/m2, followed by pharmacokinetic analysis of the 5FU plasma levels. A population pharmacokinetic analysis was performed in order to develop a compartmental pharmacokinetic model suitable for a limited sampling strategy. Clinical aspects of treating DPD-deficient patients with 5FU-based chemotherapy were assessed from the retrospectively collected clinical data. RESULTS: In a two-compartment model with Michaelis-Menten elimination, the mean maximum enzymatic conversion capacity (V(max)) value was 40% lower in DPD-deficient patients compared with controls (p < 0.001). Using a limited sampling strategy, with V(max) values calculated from 5FU concentrations at 30 or 60 minutes, significant differences were observed between DPD-deficient patients and controls at both dose levels (p < 0.001). The positive predictive value and negative predictive value for V(max), calculated from 5FU levels at 60 minutes, were 96% and 88%, respectively, in patients treated with a single dose of 5FU 300 mg/m2. All seven DPD-deficient patients (two males and five females) who had been genotyped prior to initiation of standard 5FU-containing chemotherapy developed grade 3-4 toxicity, with one case of lethal toxicity in a female patient. No grade 4 toxicity or lethal outcome was observed in 13 DPD-deficient patients treated with reduced doses of 5FU. The average dose of 5FU in DPD-deficient patients with mild toxicity (grade ≤2) was 61 ± 16% of the normal 5FU dose (n = 10). CONCLUSIONS: Profound differences in the elimination of 5FU could be detected between DPD-deficient patients and control patients. Pharmacokinetic 5FU profiling, using a single 5FU concentration at 60 minutes, may be useful for identification of DPD-deficient patients in order to reduce severe toxicity. Furthermore, treatment of DPD-deficient patients with standard 5FU-containing chemotherapy was associated with severe (lethal) toxicity.

High-level mRNA quantification of proliferation marker pKi-67 is correlated with favorable prognosis in colorectal carcinoma.

PURPOSE: The present study retrospectively examines the expression of pKi-67 mRNA and protein in colorectal carcinoma and their correlation to the outcome of patients. METHODS: Immunohistochemistry and quantitative RT-PCR were used to analyze the expression of pKi-67 in 43 archival specimens of patients with curatively resected primary colorectal carcinoma, who were not treated with neo-adjuvant therapy. RESULTS: We determined a median pKi-67 (MIB-1) labeling index of 31.3% (range 10.3-66.4%), and a mean mRNA level of 0.1769 (DeltaC(T): range 0.01-0.69); indices and levels did not correlate. High pKi-67 mRNA DeltaC(T) values were associated with a significantly favorable prognosis, while pKi-67 labeling indices were not correlated to prognostic outcome. A multivariate analysis of clinical and biological factors indicated that tumor stage (UICC) and pKi-67 mRNA expression level were independent prognostic factors. CONCLUSION: Quantitatively determined pKi-67 mRNA can be a good and new prognostic indicator for primary resected colorectal carcinoma.

Thymidylate synthase and dihydropyrimidine dehydrogenase mRNA expression levels: predictors for survival in colorectal cancer patients receiving adjuvant 5-fluorouracil.

PURPOSE: Despite adjuvant 5-fluorouracil (5-FU) therapy, approximately 30% of patients with International Union against Cancer stage II and III colorectal cancer develop recurrence. In this study, we determined the prognostic value of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) expression in colorectal cancer patients treated with adjuvant 5-FU. EXPERIMENTAL DESIGN: A real-time reverse transcription-PCR technique for quantitation of relative gene expression from paraffin-embedded specimen was established first. In a second step, archival paraffin-embedded primary tumor tissue of 309 patients who participated in adjuvant colorectal cancer trials was analyzed for TS and DPD mRNA expression. RESULTS: TS mRNA expression determined by real-time reverse transcription-PCR correlated with TS protein levels determined by TS immunoblot and immunohistochemistry in cultured colon cancer cell lines and paraffin-embedded primary tumor tissue. TS mRNA levels in fresh-frozen tissues also correlated with TS mRNA levels in corresponding paraffin sections. Among the patients receiving adjuvant 5-FU therapy, those with high TS survived longer than those with low TS, and in each TS subgroup, the ones with low DPD survived longer than the ones with high DPD levels. Multiple Cox regression analysis showed that besides tumor stage (P = 0.010), only the combination of TS and DPD expression turned out to be an independent prognostic factor for survival (P = 0.030). CONCLUSIONS: This suggests that TS and DPD quantitation may be helpful to evaluate prognosis of patients receiving adjuvant 5-FU and that patients with high TS and low DPD may benefit from adjuvant 5-FU chemotherapy.

Phase 1 trial of the novel bispecific molecule H22xKi-4 in patients with refractory Hodgkin lymphoma.

CD30 is an excellent target for immunotherapy of Hodgkin lymphoma (HL) because it is overexpressed on Hodgkin and Reed-Sternberg cells. We developed a novel bispecific molecule (BSM) consisting of F(ab') fragments derived from the murine anti-CD30 monoclonal antibody (MoAb) Ki-4 and the humanized CD64-specific MoAb H22. In vitro experiments of H22xKi-4 demonstrated specific phagocytosis of HL-derived cell lines. Patients (pts) with refractory CD30(+) HL were treated with escalating doses of H22xKi-4 at doses of 1, 2.5, 5, 10, and 20 mg/m(2)/d, respectively (administered intravenously on days 1, 3, 5, and 7). The main study objectives were to determine the maximum tolerated dose and the dose-limiting toxicities of H22xKi-4, to define its pharmacokinetic profile, and to document clinical response. Ten pts were enrolled and are evaluable for toxicity and response. Side effects were transient and mild with hypotension (4 of 10), tachycardia (6 of 10), fatigue (10 of 10), and fever (2 of 10 grade I, 3 of 10 grade II). Pharmacokinetic (PK) data revealed an elimination half-life of 11.1 hours, resulting in a significant accumulation of H22xKi-4. The BSM was shown to bind to both monocytes and malignant cells. Response to H22xKi-4 included 1 complete remission (CR), 3 partial remissions (PR), and 4 pts with stable disease. The new BSM H22xKi-4 can be given safely to pts with refractory CD30(+) HL in doses up to 80 mg/m(2) per cycle. Although this dose is not the maximum tolerated dose (MTD) as defined by toxicity criteria, surrogate parameters suggest a biologic effective regimen. H22xKi-4 shows activity in heavily pretreated HL patients warranting further clinical evaluation.

Association of time to recurrence with thymidylate synthase and dihydropyrimidine dehydrogenase mRNA expression in stage II and III colorectal cancer.

Patients with International Union Against Cancer (UICC) stage IIb and III colon cancer and stage II and III rectal cancer may receive adjuvant chemotherapy with 5-fluorouracil (5-FU). High levels of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) have been associated with resistance to 5-FU in advanced colorectal cancer. The aim of this study was to investigate the association of TS and DPD mRNA levels with recurrence-free survival in patients with colorectal cancer who are receiving adjuvant 5-FU-based chemotherapy. TS and DPD mRNA quantitation was retrospectively performed in primary colorectal cancer specimens from patients receiving adjuvant 5-FU using a reverse transcription- polymerase chain reaction technique. The median TS mRNA level in patients with a recurrence (n = 142) was 0.68, and in patients without a recurrence (n = 206) the median level was 0.80 (P < 0.01). Patients with a recurrence who had a low TS level (TS < or = 0.9; n = 102) had a median recurrence-free survival of 18 months (range 3.0 to 54 months), and those with a high TS level (TS > 0.9; n = 40) had a median recurrence-free survival of 11 months (range 1.7 to 53 months; P = 0.0024). There was no difference in the median recurrence-free survival of patients with low and high DPD mRNA levels. The TS mRNA level may be a useful marker to predict the time to recurrence in patients with colorectal cancer who are receiving adjuvant 5-FU treatment.