P53 mutation and response to hepatic arterial floxuridine in patients with colorectal liver metastases.

PURPOSE: To establish the relationship between the number and site of p53 genomic mutations in metastatic colorectal cancer, and the response to hepatic arterial floxuridine. METHODS: Liver metastasis biopsies were collected, at the time of laparotomy for hepatic arterial cannulation. in 28 patients with metachronous colorectal liver metastases. p53 Gene mutations were assessed using reverse transcription, nested polymerase chain reaction, single strand conformational polymorphism and gene sequencing. Chemotherapy response was determined from computerised liver tomograms after 4 months of treatment. RESULTS: Liver metastasis p53 mutation was identified in 21 (75%), and p53 "hot spot" mutation in 11 (39%) patients. There was a significantly lower prevalence (Fisher's, P=0.001) of patients with p53 "hot spot"-mutated liver metastases in stable disease and partial response (5/22) than in progressive (6/6) disease groups. Significantly fewer (Mann-Whitney U, P=0.002) p53 "hot spot" mutations/biopsy were observed in liver metastases from stable disease and partial response (median 0, iqr. 0-0) than in progressive (median 1, iqr 1-2) disease patients. p53 "Hot spot"-mutated liver metastases were associated with significantly shorter survival times (logrank P=0.05) after hepatic arterial floxuridine. Significant response or survival-time differences by total or L2/L3 zinc-binding site p53 mutations were not detected. CONCLUSIONS: The results support a role for p53 "hot spot" mutations in colorectal liver metastasis resistance to fluorinated pyrimidines, and suggest that the presence of such mutations may be a contra-indication to treatment of colorectal liver metastases with hepatic arterial floxuridine.

P53 mutations in primary and metastatic tumors and circulating tumor cells from colorectal carcinoma patients.

Circulating tumor cells could provide a relatively noninvasive and repeatable source of information about tumor cell genotype that might influence treatment and estimation of prognosis. We developed a technique for identifying p53 mutations in tumor cells isolated from the peripheral venous blood of colorectal cancer patients and compared the prevalence and position of these mutations with multiple solid tumor samples from the same patient. We used immunomagnetic beads to isolate tumor cells, reverse transcriptase-nested polymerase chain amplification of the coding region between exons 4 and 9 within the p53 gene, and automated gene sequencing. Nineteen p53 mutations were detected in solid tumor samples from 19 of 41 colorectal carcinoma patients. An identical p53 mutation was invariably present in all samples from primary and metastatic colorectal tumor biopsies within the same patient. p53 mutations were detected in peripheral blood from 8 of these 19 patients with p53-mutated solid tumors. Where identified, the pattern of mutation in peripheral blood samples was invariably the same as in matching solid tumor samples. A single colorectal carcinoma biopsy provided reliable p53 gene mutational information in colorectal carcinoma. Detection of this p53 mutation in tumor cells from peripheral blood was achieved with an approach based on cell selection for epithelial characteristics, reverse transcription-PCR, and gene sequencing.

'Naïve' and 'memory' CD4+ T-cells and T-cell receptor (TCR) V beta repertoire dynamics are independent of the levels of viremia following HIV seroconversion.

The progression of 'naive' and 'memory' T-cells and the T-cell receptor Vbeta (TCR Vbeta) repertoire dynamics within the peripheral CD4+ T-cell compartment were studied in individuals following HIV seroconversion. Profound TCR Vbeta repertoire perturbations were observed within the CD4+ T-cell pool in treatment-naive patients regardless of their levels of viremia during the first 6-8 months after seroconversion. The ratio of 'naive' to 'memory' CD4+ T-cells as well as the TCR Vbeta repertoire dynamics did not appear to correlate with absolute numbers of CD4 T-cells.