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Biomedical subjects

R T Penson

Publications and source records attributed to R T Penson.

39 records · Page 3Linked to original sources

A phase II study of fixed dose rate gemcitabine in patients with relapsed müllerian tumors.

Gemcitabine (2',2'-difluorodeoxycytidine) is a novel purine analog with clinical activity against ovarian cancer. Accumulation of gemcitabine triphosphate (dFdCTP) increases in a linear fashion with prolonged infusions of gemcitabine, and there is a strong relationship between intracellular accumulation of dFdCTP and DNA damage. Women with ovarian, fallopian tube, or primary peritoneal carcinoma and documented recurrent disease were eligible for the study. Patients could not have received more than four prior lines of chemotherapy and had to have measurable or evaluable disease. Gemcitabine 800 mg/m2 administered by intravenous infusion at 10 mg/m2/min (fixed dose rate [FDR]) on days 1 and 8 of a 21-day schedule. Twenty-eight patients with a median age 60 (range, 40-77) years were treated. Although 43% were Eastern Cooperative Oncology Group 0, 50% had liver metastases. Eighty-eight cycles of therapy were delivered (median 2 [range, 1-6]). Five of the first ten patients treated at 800 mg/m2 could not receive day 8 FDR-gemcitabine because of neutropenia, and the starting dose was reduced to 700 mg/m2. Even at this dose there was cumulative hematologic toxicity resulting in dose reductions. Vomiting, mucositis, diarrhea, allergy, rash, fever, and alopecia were mild. In 28 patients, there was only one partial response (4%, 95% CI 0-18%) and median time to progression was 1.7 (interquartile range, 1.2-3.9) months. FDR-gemcitabine 700 mg/m2 administered by intravenous infusion at an FDR of 10 mg/m2/min had minimal activity against heavily pretreated recurrent tumors of müllerian origin. The optimal dose and schedule of gemcitabine is yet to be defined in this population.

Adenocarcinoma↗

Overexpression of human phosphoglycerate kinase 1 (PGK1) induces a multidrug resistance phenotype.

BACKGROUND: Multidrug resistance is a significant barrier to the development of successful cancer treatment. To identify genetic alterations that are directly involved in paclitaxel resistance, a functional cloning strategy was developed. MATERIALS AND METHODS: Using mRNA from paclitaxel resistant human ovarian cancer cell line SW626TR, a cDNA library was established in a pCMV-Script vector that permits expression of cDNA inserts in mammalian cells. Transfection of the pCMV-Script/SW626TR cDNA library into the paclitaxel-sensitive human osteogenic sarcoma cell line, U-20S, resulted in several paclitaxel-resistant clones. RESULTS: DNA sequencing of clone C16 demonstrates complete homology to human phosphoglycerate kinase 1 (PGK1). Retransfection of the PGK1 insert into U-20S confers a multidrug resistant phenotype, characterized by a 30-fold increase in paclitaxel resistance, and cross-resistance to vincristine; adriamycin and mitoxantrone, but not methotrexate or cisplatin. Enzymatic analysis of the PGK1 transfectants demonstrates an increase in PGK1 activity as compared to the parental cell line, U-20S. Northern and Western analysis of PGK1 transfectants reveals no change in MDR-1 expression compared with the parental cell line. In addition, co-culture of PGK1 transfectants with verapamil only partially reverses the multidrug resistant phenotype. Rhodamine 123 studies are also consistent with an MDR-1 independent mechanism of increased drug efflux. CONCLUSION: Together this data suggests that PGK1 can induce a multidrug resistant phenotype through an MDR-1 independent mechanism.

Antineoplastic Agents↗