Tumor quantification of several fluoropyrimidines resistance gene expression with a unique quantitative RT-PCR method. Implications for pretherapeutic determination of tumor resistance phenotype.

International audiencePretherapeutic determination of tumor resistance to chemotherapy is a main challenge, hindered by the low number of mechanisms characterized at the same time, the small size of the clinical specimens and the heterogeneity of the techniques or the lack of true quantification. The aim of the present study was to determine in real time quantitative RT-PCR, tumor cell expression of several transcripts involved in cancer cell resistance with a unique cDNA sample from a tumor biopsy. The technique had to be suitable in clinical practice for determination of several factors involved in resistance to a given drug family, for example, fluoropyrimidines resistance factors: thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine kinase (TK), dihydrofolate reductase (DHFR), folylpolyglutamate synthetase (FPGS). A frame-shifted artificial construct was designed specifically to work within the same conditions. We validated our technique by quantifying expressions of these 5 genes starting from tissue samples of colorectal carcinoma and the surrounding normal mucosa of 33 different patients. That real time quantitative RT-PCR technique using the frame-shifted artificial construct as a standard provided a real comparison and quantification of different resistance factors. Tumor resistance phenotype determination based on that approach will be investigated in a control study

Cetuximab pharmacokinetics influences progression-free survival of metastatic colorectal cancer patients

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Influence of FCGRT gene polymorphisms on pharmacokinetics of therapeutic antibodies

International audienceThe neonatal Fc receptor (FcRn) encoded by FCGRT is known to be involved in the pharmacokinetics (PK) of therapeutic monoclonal antibodies (mAbs). Variability in the expression of FCGRT gene and consequently in the FcRn protein level could explain differences in PK observed between patients treated with mAbs. We studied whether the previously described variable number tandem repeat (VNTR) or copy number variation (CNV) of FCGRT are associated with individual variations of PK parameters of cetuximab. VNTR and CNV were assessed on genomic DNA of 198 healthy individuals and of 94 patients treated with the therapeutic mAb. VNTR and CNV were analyzed by allele-specific PCR and duplex real-time PCR with Taqman (®) technology, respectively. The relationship between FCGRT polymorphisms (VNTR and CNV) and PK parameters of patients treated with cetuximab was studied. VNTR3 homozygote patients had a lower cetuximab distribution clearance than VNTR2/VNTR3 and VNTR3/VNTR4 patients (p = 0.021). We observed no affects of VNTR genotype on elimination clearance. One healthy person (0.5%) and 1 patient (1.1%) had 3 copies of FCGRT. The PK parameters of this patient did not differ from those of patients with 2 copies. The FCGRT promoter VNTR may influence mAbs' distribution in the body. CNV of FCGRT cannot be used as a relevant pharmacogenetic marker because of its low frequency

Aerosolized Chemotherapy

International audienceRegional chemotherapy has been proposed as a treatment modality in a number of cancer settings. In primary or metastatic lung cancer, administration of chemotherapy via inhalation could increase exposure of lung tumor to the drug, while minimizing systemic side effects. Several proof of concept studies in animal models of metastatic or primary lung cancer have demonstrated the safety, pharmacokinetic advantage, and antitumor effect of aerosol administration of several chemotherapeutic agents including doxorubicin, gemcitabine and liposome-encapsulated formulations of paclitaxel and 9-nitrocamptothecin (9-NC). Recent phase I studies have demonstrated the feasibility of aerosol delivery of doxorubicin and liposomal formulations of 9-NC and cisplatin in patients with primary and metastatic lung cancer with a limited pharmacokinetic profile consistent with the observed low systemic toxicity. Further studies integrating safety, pharmacokinetic, and efficacy considerations are required to determine whether there is a place for local administration of chemotherapy via inhalation in lung cancer.</p

A multicenter phase II study of personalized FOLFIRI-cetuximab for safe dose intensification

International audienceWe conducted a multicenter proof of concept phase II trial in patients with advanced colorectal cancer receiving FOLFIRI-cetuximab regimens to explore individual drug tailoring using pharmacogenetics and pharmacokinetics (PK) monitoring. Patients were stratified by their pharmacogenetic/phenotypic status: the irinotecan dose was adjusted according to the number of TA tandem repeats in the UGT1A1 promoter, while the 5-fluorouracil (5-FU) dose was initially adjusted according to dihydropyrimidine dehydrogenase (DPD) activity at initial screening (5-FU[ODPM Tox]) followed by PK-guided dose optimization (5-FU[ODPM Protocol]). An advanced cetuximab PK/pharmacodynamics (PD) study was performed but dosage remained unchanged. Eighty-five patients receiving second-line chemotherapy were enrolled. Mean irinotecan doses at 3 months were 247 ± 50, 210 ± 53 and 140 ± 21 mg/m[2] for those with 6/6 (33), 6/7 (26), and 7/7 (7) TATA repeats in the UGT1A1 promoter region, respectively. The 5-FU dose was initially reduced in four patients with DPD deficiency, but mean 5-FU dose at 3 months was 2,412 ± 364 mg/m2 (1,615-3,170 mg/m[2]). Grade 4 toxicities were not encountered and grade 4 neutropenia occurred in 6.8%, 5.9%, and 0% of patients with 6/6, 6/7, and 7/7 UGT1A1 genotypes. The objective response rate was 25.8% among the 85 patients, 57.3% in patients with tumors wild type (WT) for KRAS, and 25% in those whose tumor harbored a mutant-KRAS. Secondary resection of hepatic metastases was performed in 31.7% of patients. Median progression-free survival (PFS) for all 85 patients was 181 days and 200, 132, and 121 days for patients with 6/6, 6/7, and 7/7 UGT1A1 genotypes, respectively; these differences were not statistically different. In parallel, a strong relationship was shown between cetuximab AUC and regimen efficacy. We conclude that personalized drug tailoring when administering in FOLFIRI + cetuximab allows for safe and efficient individual dose intensification