(1/4604) Electronic volume analysis of L1210 chemotherapy.
The rapid analysis of in vivo chemotherapy on the L1210 ascites tumor grown in C57BL/6 X DBA/2F1 mice has been shown by means of an electronic volume analysis. The drugs were injected on the 4th day of tumor growth, and the cells in the peritoneal cavity were studied at 24-hr intervals on the 5th through 7th day. Using the electronic cell volume distributions, combined with labeling indices, cell morphology, and cell counts, it was found that the alkylating agents. 1,3-bis(2-chloroethyl)-1-nitrosourea and cyclophosphamide, at the dosages used, were more effective than the S-phase-specific drugs, palmitoyl ester of 1-beta-D-arabinofuranosylcytosine, vincristine, and methotrexate. (+info)
(2/4604) Tissue pharmacokinetics, inhibition of DNA synthesis and tumor cell kill after high-dose methotrexate in murine tumor models.
In Sarcoma 180 and L1210 ascites tumor models, the initial rate of methotrexate accumulation in tumor cells in the peritoneal cavity and in small intestine (intracellularly) after s.c. doses up to 800 mg/kg, showed saturation kinetics. These results and the fact that initial uptake in these tissues within this dosage range was inhibited to the expected relative extent by the simultaneous administration of leucovorin suggest that carrier mediation and not passive diffusion is the major route of drug entry at these extremely high doses. Maximum accumulation of intracellular drug occurred within 2 hr and reached much higher levels in small intestine than in tumor cells at the higher dosages. At a 3-mg/kg dose of methotrexate s.c., intracellular exchangeable drug levels persisted more than four times longer in L1210 cells than in small intestine, but differences in persistence (L1210 cell versus gut) diminished markedly with increasing dosage. At 96 mg/kg, the difference in persistence was less than 2-fold. In small intestine and L1210 cells, theduration of inhibition of DNA synthesis at different dosages correlated with the extent to which exchangeable drug was retained. Toxic deaths occurred when inhibition in small intestine lasted longer than 25 to 30 hr. Recovery of synthesis in small intestine and L1210 cells occurred synchronously and only below dosages of 400 mg/kg. Within 24 hr after dosages of greater than 24 mg/kg, the rate of tumor cell loss increased to a point characterized by a single exponential (t1/2=8.5 hr). The total cell loss, but not the rate of cell loss, was dose dependent. (+info)
(3/4604) Modulation of the cytotoxicity of 3'-azido-3'-deoxythymidine and methotrexate after transduction of folate receptor cDNA into human cervical carcinoma: identification of a correlation between folate receptor expression and thymidine kinase activity.
Cervical carcinoma is an AIDS-defining illness. The expression of folate receptors (FRs) in cervical carcinoma (HeLa-IU1) cells was modulated by stable transduction of FR cDNA encapsidated in recombinant adeno-associated virus-2 in the sense and antisense orientation (sense and antisense cells, respectively). Although sense cells proliferated slower than antisense or untransduced cells in vivo and in vitro in 2% (but not 10%) FCS, [methyl-3H]thymidine incorporation into DNA was significantly increased in sense cells in 10% serum; therefore, the basis for this discrepancy was investigated. The activity of thymidine kinase (TK) was subsequently directly correlated with the extent of FR expression in single cell-derived clones of transduced cells. This elevated TK activity was not a result of recruitment of the salvage pathway based on the presence of adequate dTTP pools, normal thymidylate synthase (TS) activity, persistence of increased thymidine incorporation despite the exogenous provision of excess 5,10-methylene-tetrahydrofolate, and documentation of adequate folates in sense cells. The increase in TK activity conferred significant biological properties to sense cells (but not antisense or untransduced cells) as demonstrated by augmented phosphorylation of 3'-azido-3'-deoxythymidine (AZT) and concomitantly greater sensitivity to the cytotoxic effects of AZT. Conversely, sense cells were highly resistant to methotrexate, but this was reversed by the addition of AZT. The direct correlation of FR expression and TK activity indicates a previously unrecognized consequence of FR overexpression. (+info)
(4/4604) Reduced folate carrier expression in acute lymphoblastic leukemia: a mechanism for ploidy but not lineage differences in methotrexate accumulation.
Methotrexate (MTX) is one of the most active and widely used agents for the treatment of acute lymphoblastic leukemia (ALL). To elucidate the mechanism for higher accumulation of MTX polyglutamates (MTX-PG) in hyperdiploid ALL and lower accumulation in T-lineage ALL, expression of the reduced folate carrier (RFC) was assessed by reverse transcription-polymerase chain reaction in ALL blasts isolated from newly diagnosed patients. RFC expression exhibited a 60-fold range among 29 children, with significantly higher expression in hyperdiploid B-lineage ALL (median, 11.3) compared with nonhyperdiploid ALL (median, 2.1; P <.0006), but no significant difference between nonhyperdiploid B-lineage and T-lineage ALL. Furthermore, mRNA levels of RFC (mapped by FISH to chromosome 21) were significantly related to chromosome 21 copy number (P =.0013), with the highest expression in hyperdiploid ALL blasts with 4 copies of chromosome 21. To assess the functional significance of gene copy number, MTX-PG accumulation was compared in ALL blasts isolated from 121 patients treated with either low-dose MTX (LDMTX; n = 60) or high-dose MTX (HDMTX; n = 61). After LDMTX, MTX-PG accumulation was highest in hyperdiploid B-lineage ALL with 4 copies of chromosome 21 (P =.011), but MTX-PG accumulation was not significantly related to chromosome 21 copy number after HDMTX (P =.24). These data show higher RFC expression as a mechanism for greater MTX accumulation in hyperdiploid B-lineage ALL and indicate that lineage differences in MTX-PG accumulation are not due to lower RFC expression in T-lineage ALL. (+info)
(5/4604) Role of folylpolyglutamate synthetase and folylpolyglutamate hydrolase in methotrexate accumulation and polyglutamylation in childhood leukemia.
Inefficient polyglutamylation is a mechanism of resistance to methotrexate (MTX) in childhood T-lineage acute lymphoblastic leukemia (T-ALL) and in acute myeloid leukemia (AML) in comparison with childhood c/preB-ALL. We analyzed the profile of MTX polyglutamylation in childhood c/preB-ALL, T-ALL, and AML (n = 45, 15, and 14, respectively), the activity of the MTX-polyglutamate synthesizing enzyme folylpolyglutamate synthetase (FPGS) (n = 39, 11, and 19, respectively) and of the MTX-polyglutamate breakdown enzyme folylpolyglutamate hydrolase (FPGH) (n = 98, 25, and 34, respectively). MTX-Glu4-6 accumulation after 24 hours exposure to 1 micromol/L [3H]-MTX in vitro was lower in T-ALL (threefold) and AML (fourfold) compared with c/preB-ALL (P =.001). The FPGS activity was twofold lower in T-ALL and AML than in c/preB-ALL samples (P <. 01). FPGH activity was not different between c/preB-ALL and T-ALL, but threefold higher in AML (P <.001). FPGS, FPGH, and the ratio FPGS/FPGH were correlated with MTX-Glu4-6 accumulation (r =.49, r = -.34 and r =.61, respectively). Multivariate analysis showed that FPGS, but not FPGH, was an independent contributor for MTX-Glu1-6 accumulation, but not for MTX-Glu4-6 accumulation. In conclusion, low FPGS activity is associated with low accumulation of MTX-Glu4-6 in T-ALL and AML. For the group of AML as compared with the group of ALL, a high FPGH activity can play an additional role. (+info)
(6/4604) Multimodality therapy for locally advanced and limited stage IV breast cancer: the impact of effective non-cross-resistance late-consolidation chemotherapy.
To determine the effectiveness of non-cross-resistant late-consolidation chemotherapy in locally advanced breast cancer (LABC) and stage IV breast cancer, we review our experience with two regimens. Between 1985 and 1991, we enrolled 56 patients with LABC, who were treated with a doxorubicin-based adjuvant regimen, followed by a late-consolidation non-cross-resistant regimen containing methotrexate, 5-fluorouracil, cisplatin, and cyclophosphamide. Between 1985 and 1996, a total of 45 patients with limited stage IV breast cancer underwent surgical excision of all evaluable disease, making them metastatic (stage IV) with no evaluable disease. Surgery was followed by a doxorubicin-containing regimen and then a late-consolidation non-cross-resistant regimen, which was either methotrexate, 5-fluorouracil, cisplatinum, and cyclophosphamide or 5-fluorouracil, mitomycin, etoposide, and cisplatin. Twenty-four patients with limited bone metastases that were unresectable were treated with a doxorubicin-containing regimen, radiation therapy to all sites of disease, and then one of the two late non-cross-resistant regimens. With a median follow-up of 84 months, 78% of patients with LABC are alive, and 68% are free of disease. After a median follow-up of 44 months, 53% of patients with stage IV with no evaluable disease are alive and free of disease. The use of non-cross-resistant late-consolidation chemotherapy is an effective strategy in the treatment of patients with LABC and selected patients with limited stage IV breast cancer. (+info)
(7/4604) High dose chemotherapy with busulfan, cyclophosphamide, and etoposide as conditioning regimen for allogeneic bone marrow transplantation for patients with acute myeloid leukemia in first complete remission.
We explored the combination of busulfan/cyclophosphamide/etoposide as conditioning regimen prior to bone marrow transplantation in 31 patients with acute myeloid leukemia (AML) in first complete remission. The preparative regimen consisted of 16 mg/kg busulfan, 30-60 mg/kg VP-16, and 120 mg/kg cyclophosphamide. With a median follow-up of 30.5 months (range, 5-60 months), 25 patients are alive in continuous complete remission. Estimated disease-free survival at 5 years is 80.5%. Death was due to transplant-related toxicity (graft-versus-host disease and cytomegalovirus infection, graft-versus-host disease and pneumonia, sepsis and mucositis, respectively). None of the patients have relapsed. As demonstrated by the results of this analysis, the conditioning regimen busulfan/cyclophosphamide/etoposide is effective and well tolerated in patients with AML in first complete remission. Main nonhematological toxicities were mucositis and hepatotoxicity. The low mortality and relapse rate appears to justify allogeneic bone marrow transplantation for patients with AML in first complete remission who have an HLA-identical donor. Whether this regimen offers a substantial improvement in disease-free and overall survival over presently used regimens warrants further investigation. (+info)
(8/4604) The effectiveness of non-surgical management of early interstitial pregnancy: a report of ten cases and review of the literature.
OBJECTIVE: To assess the effectiveness of non-surgical management of interstitial pregnancy. DESIGN: A prospective interventional study. SUBJECTS: Eleven women with the ultrasound diagnosis of interstitial ectopic pregnancy. METHODS: Women with suspected early pregnancy complications were examined by transvaginal ultrasound. Those with the diagnosis of interstitial pregnancy were offered non-surgical treatment with methotrexate, which was administered systemically or by local injection. Follow-up with regular measurements of beta-human chorionic gonadotropin and ultrasound scans continued until the pregnancy had resolved completely. RESULTS: Ten women were managed non-surgically, and one woman opted for surgery. Five women received systemic and five local methotrexate. Local therapy was successful in all five cases (100%), whereas four out of five (80%) women receiving systemic methotrexate were cured. Significant side-effects were noted in two women following systemic therapy. In comparison, there were no side-effects in the group of women who received local therapy. There were no significant differences between the two treatment groups in the length of time taken for the pregnancy to resolve. CONCLUSIONS: Non-surgical treatment of interstitial pregnancy with methotrexate appears to be safe and effective. Local administration appears to be more successful and better tolerated by patients and may be used as the first-line therapy. (+info)