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Reversal of methotrexate toxicity in mice by 5-methyltetrahydrofolic acid.

1. Mice have been compeletly protected against the lethal effects of repeated injections of methotrexate by 5-methyltetrahydrofolic acid. Methotrexate-resistant cells probably owe their resistance to their high content of this substance.2. Daily small doses were much more effective than fewer but larger doses.3. The reduced efficiency found in counteracting high dosages of methotrexate may be due to interference with folate transport across cell walls.4. 5-Methyltetrahydrofolic acid and citrovorum factor did not differ greatly in their ability to inhibit methotre toxicity. It is suggested that the pharmaceutical effects of citrovorum factor are due to its conversion to 5-methyltetrahydrofolic acid.

Animals↗

Flow microfluorometric patterns of human bone marrow and tumor cells in response to cancer chemotherapy.

A rapid propidium iodide staining method was used for analysis of single-cell suspensions of bone marrow and tumor biopsies by flow microfluorometry. With this technique, information on the proliferative status of target tissues can be obtained within 10 min of sample removal. DNA histograms and labeling index of sequential bone marrow biopsies from a patient with Stage IV diffuse lymphocytic leukemia and treated with 1-beta-D-arabinofuranosylcytosine infusion showed pronounced reduction in the percentage of cycling cells. In contrast, sequential tumor biopsies from a melanoma patient on methotrexate-citrovorum factor rescue therapy showed no changes. In sequential bone marrow biopsies of 3 patients on high-dose methotrexate-citrovorum factor rescue, initial accumulation of cells in G1-S (Day 1) was followed by a significant proliferative response (Days 4 to 7) and return to pretherapy values. In contrast, no recovery similar to that of the bone marrow was seen in tumor cells.

Antineoplastic Agents↗

Role of thymidylate synthetase activity in development of methotrexate cytotoxicity.

Methotrexate (MTX) inhibition of the growth of mouse or human leukemia cells in culture was partially prevented by either thymidine (dThd) or hypoxanthine. 5-Fluoro-2'-deoxyuridine (FdUrd) also decreased the growth-inhibitory potency of MTX in the presence of small concentrations of 5-formyltetrahydrofolate (citrovorum factor) and sufficient exogenous dThd to support the synthesis of thymidylate nucleotides by salvage mechanisms. In addition, citrovorum factor-induced reversal of MTX was several orders of magnitude more efficient in the presence of both FdUrd and dThd than in the presence of dThd alone or in the absence of both nucleosides. Likewise, the presence of FdUrd (3 microM) and dThd (5.6 microM) completely prevented the lethality of 0.3 mM MTX to L1210 cells in culture medium supplemented with micromolar concentrations of citrovorum factor. We propose that this protection against the cytotoxic effects of MTX by dThd, hypoxanthine, and FdUrd have a common biochemical mechanism--namely, inhibition of the de novo synthesis of thymidylate by either a direct [FdUrd; inhibition of thymidylate synthetase (thymidylate synthase; 5,10-methylenetetrahydrofolate:dUMP C-methyl-transferase, EC 2.1.1.45)] or indirect (dThd and hypoxanthine; feedback inhibition by anabolites on ribonucleotide reductase and deoxycytidylate deaminase) effect. The resultant decreased rate of loss of reduced folates due to de novo thymidylate synthesis would allow a higher degree of inhibition of dihydrofolate reductase to be endured without damage to the cell.

Animals↗

Systemic absorption of a leucovorin mouth wash: a pharmacologic study.

Mucositis is one of the major problems encountered after the administration of systemic chemotherapy. Leucovorin, routinely used as a rescue agent for methotrexate may reduce toxicity, but may also reduce the effectiveness of the chemotherapeutic agent. If leucovorin is administered as a mouth wash, local toxicity may be reduced without loss of methotrexate efficacy. In order to study this, 15 normal human volunteers were given leucovorin mouth wash and then had plasma determinations of 5-methyl-tetrahydrofolate and citrovorum factor. Small but statistically significant increases in plasma levels of 5-methyl-tetrahydrofolate were observed with no increase in levels of plasma citrovorum factor. It is concluded therefore that a small amount of leucovorin is absorbed systemically when administered as a mouth wash, but such an amount would most likely not be significant enough to reduce the effect of methotrexate therapy, but may reduce mucositis.

Absorption↗

Renal toxicity with cumulative doses of cis-diamminedichloroplatinum-II in pediatric patients with osteosarcoma. Effect on creatinine clearance and methotrexate excretion.

Sequential corrected creatinine clearance (CCC) evaluations were obtained in 30 patients treated with intra-arterial and/or intravenous cis-diamminedichloroplatinum-II (CDP). The dose was 150 mg/M2 administered with mannitol diuresis at 2 to 3 weekly intervals. Four hundred fifty-three courses were administered (range, 6-18) over 18 months. Patients also were treated with 283 courses of high-dose methotrexate (MTX) and citrovorum factor "rescue" which were interposed between treatments. Deleterious effects of cumulative courses of CDP manifested as progressive reductions in CCC and delayed excretion of serum MTX. Severe MTX toxicity was aborted by augmenting the fluid intake and prolonging citrovorum factor rescue when elevated levels of serum MTX were detected. The first indication of renal induced CDP toxicity occurred with a cumulative dose of 450 mg/M2. At the termination of treatment (cumulative CDP dose over 1050 mg/M2) renal impairment still was present.

Child↗

A radioimmunoassay for methotrexate and its comparison with spectrofluorimetric procedures.

A radioimmunoassay procedure has been developed for the direct measurement of methotrexate (MTX) in plasma, serum, cerebrospinal fluid, or urine samples. The assay is sensitive to levels of at least 100 pg of MTX and is highly specific for MTX in the presence of folinic acid (citrovorum factor), folic acid, tetrahydrogolic acid, and other folate analogs and known metabolites. Results from this procedure have been compared with those obtained with a spectrofluorimetric method, utilizing the plasma of cancer patients undergoing high-dose MTX treatment with citrovorum factor rescue. Results indicate that the method should be usful in the future in assisting individualization of dosage regimens and in the study of the pharmacokinetics and metabolism of MTX in cancer patients.

Carrier Proteins↗

[Postoperative adjuvant chemotherapy of high dose MTX for osteogenic sarcoma].

There are still some controversy on the role of adjuvant chemotherapy in the treatment of osteogenic sarcoma, and no relevant report has been published in Chinese medical literature. In this paper 15 patients with osteogenic sarcoma treated from March 1982 to March 1986 by high dose MTX with citrovorum factor rescue after surgery are reported. Another 15 patients treated by surgical amputation alone during the same period served for comparison. The sex, age and site of the tumor in the two groups were comparable. In the treated group, MTX 0.7-1.4 g/m2, averaged 0.92 g/m2 were given intravenously, followed by citrovorum factor rescue, once a month for 2-12 injections. 12 patients (80%) in this group were given more than 4 injections. All patients tolerated the treatment well and no death was ascribed to the treatment. The patients were followed for 7-48 months, in the HD-MTX treated group, 1 patient was lost in the follow up, 9 died and 5 were still alive (35.7%). In the comparison group, 2 were lost, 11 died and only 2 were still alive (15.4%). The 2 year survival rate for the treated group was 57.1% and 30.8% for the comparison group (P greater than 0.05). The authors suggest that the dose of MTX be increased and combined with other cytostatic drugs like doxorubicin and cisplatin when necessary for better results. Adjuvant chemotherapy has definite value in the treatment of osteogenic sarcoma if adequate dose and protocols are used. However, the best adjuvant chemotherapy program for Chinese patients still remains to be studied.

Adolescent↗

High-dose methotrexate for the remission induction of refractory adult acute lymphocytic leukemia.

Six adults with refractory acute lymphocytic leukemia (ALL) were treated with high-dose methotrexate, citrovorum factor, and vincristine. All patients had previously received extensive treatment with standard therapeutic agents, including vincristine, and all but one had received prior methotrexate. Two patients achieved complete remission and one achieved partial remission. Responses were seen at 3--6 gm/m2 of methotrexate. The durations of remission were 7--10 weeks. High-dose methotrexate with citrovorum factor is effective in the treatment of advanced ALL and should be considered for inclusion in initial combination chemotherapeutic regimens for adult ALL.

Adult↗

Phase II study of high-dose methotrexate in the treatment of patients with non-small cell carcinoma of the lung: an Eastern Cooperative Oncology Group study.

Twenty-eight patients with inoperable non-small cell carcinoma of the lung were treated with high-dose methotrexate with citrovorum factor rescue. One patient (4%) responded with a partial regression of the tumor. Three patients had severe or life-threatening complications: acute renal failure, acute shortness of breath, and bone marrow suppression, respectively. There is 98% confidence that the true response rate for this therapy is less than 20%. The results of this study demonstrate that high-dose methotrexate with citrovorum factor rescue, in the schedule utilized, is not effective in the treatment of patients with non-small cell carcinoma of the lung.

Aged↗

Combination chemotherapy with bleomycin, cyclophosphamide and dactinomycin for the treatment of osteogenic sarcoma.

Thirteen patients with osteogenic sarcoma were treated with multiple drug chemotherapy consisting of bleomycin, cyclophosphamide and dactinomycin. The dosage schedule used was: bleomycin 12 mg/m2/day, cyclophosphamide 600 mg/m2/day, and dactinomycin 450 microgram/m2/day. All drugs were given intravenously for two consecutive days. Treatment was repeated every 2 weeks. Toxicity included severe nausea and vomiting (managed with antiemetics and intravenous hydration) and manifestations of bone marrow depression. Of 13 patients, eight were previously treated with high dose methotrexate with citrovorum factor rescue, cyclophosphamide and Adriamycin. Of these eight, three patients had objective evidence of tumor regression (37.5%). Five of five previously untreated patients had objective evidence of tumor regression. The overall response rate in osteogenic sarcoma patients to BCD was 61.5%. The combination of BCD appears to be more active against osteogenic sarcoma than cyclophosphamide alone or Adriamycin alone. The relative safety with which BCD can be administered makes this combination a valuable adjunct to high dose methotrexate with citrovorum factor rescue and Adriamycin in the treatment of osteogenic sarcoma.

Adolescent↗

Toxicity associated with combination chemotherapy for osteosarcoma: a report of the cooperative osteosarcoma study (COSS 80).

The treatment-associated toxicity in 189 patients entered in the COSS-80 Study was analyzed. The sequential use of high-dose methotrexate (HDMTX) with citrovorum factor rescue (CFR) and cis-platinum may be additive or synergistic in causing renal toxicity. However, evaluation of the 48-h serum methotrexate level and the incidence of elevated serum creatinine levels throughout treatment failed to indicate prolonged methotrexate elimination or severe kidney damage from this regimen where an interval of 3 weeks between cis-platinum administration and the next course of HDMTX was mandatory. The treatment-related mortality was 3.2% (6 out of 189 patients). Three patients died of septicemia during chemotherapy-induced bone-marrow depression following treatment with adriamycin or the combination of bleomycin, cyclophosphamide, and dactinomycin (BCD). Three deaths occurred following the use of high-dose methotrexate with citrovorum factor rescue. Two of these deaths were associated with delayed excretion of methotrexate. The toxicity is within the range reported in the literature.

Acute Kidney Injury↗

High-dose methotrexate for advanced breast cancer.

High-dose infusions of methotrexate with citrovorum factor rescue were evaluated in 27 patients with advanced recurrent breast cancer who had previously been treated with various Adriamycin-containing regimens. Eight of 27 patients (29%) achieved objective tumor regression with a median duration of response of 26 weeks. Nineteen patients had previously received standard doses of methotrexate (less than 50 mg/m2/dose), while eight patients had had no prior exposure to methotrexate. The response rates observed in these two groups of patients were similar. Except for two drug-related deaths, toxic effects were acceptable. Myelosuppression was mild, transient, and noncumulative. Gastrointestinal toxic effects did not appear to be dose-related and were mild in most instances. Central nervous system dysfunction with lethargy, fatigability, confusion, and disorientation was the most significant toxic effect of this high-dose methotrexate therapy and was observed in six (22%) of the patients. In two patients treatment with this program was discontinued because of the development of renal dysfunction. High-dose methotrexate with citrovorum factor rescue appears to be an effective regimen in patients with advanced refractory breast cancer. However, in view of the enormous cost necessitated by this treatment approach, we do not feel further studies would be worthwhile.

Age Factors↗

[Analysis of cytotoxicity in cultured choriocarcinoma cell lines using methotrexate and actinomycin-D].

The cytotoxicity of methotrexate (MTX) and actinomycin-D (Act-D), and the influence of Citrovorum factor on MTX-treated cells were analyzed in vitro, using two choriocarcinoma cell lines (BeWo and SCH). HCG and beta-HCG in medium were measured with a radioimmunoassay kit, and 3H-MTX,-thymidine, and-uridine with a liquid scintillation counter. The following results were obtained. The MTX resistant cell line of BeWo, named BeWo, was selected by continuous exposure to increasing concentration of MTX in culture medium. The resistant cell was 50 to 100 times as resistant to MTX as the parent BeWo to the inhibition of cell growth and the development of resistance was accompanied by two-third decrease in 3H-MTX transport. The cytotoxicity of MTX and Act-D were found to increase linearly with the drug dose for concentrations between 10(-9) and 10(-4)M, 10(-10) and 10(-7)M, respectively. Act-D caused lethal damage in three choriocarcinoma cells (BeWo, SCH and BeWo) at one-thousandths the concentration of MTX. Citrovorum factor given within twelve hours following the start of methotrexate administration decreased in 3H-MTX transport and inhibited MTX-induced growth.

Cell Division↗

Effects of prophylactic chemotherapy for persistent trophoblastic disease in patients with complete hydatidiform mole.

Seventy-one patients with complete hydatidiform mole were prospectively randomized into two groups: one group (39 patients) was treated with a single course of methotrexate and citrovorum factor rescue as chemoprophylaxis; the other group (32 patients) was not treated. After molar evacuation, four patients from the treated group (10.3%) and ten patients from the untreated group (31.3%) developed persistent trophoblastic disease. The time interval from evacuation of the mole to diagnosis of persistent trophoblastic disease was longer in the treated group than in the untreated group (9.5 +/- 2.4 weeks versus 5.1 +/- 1.6 weeks, P less than .05). Among high-risk patients, there was a lower incidence of persistent trophoblastic disease in the treated group than in the untreated group (14.3 versus 47.4%, P less than .05). Among low-risk patients there was no difference between the groups (5.6 versus 7.7%, P greater than .05). All 14 patients with persistent trophoblastic disease achieved complete remission with therapeutic chemotherapy. More courses of chemotherapy were required until complete remission in the treated group than in the untreated group (2.5 +/- 0.5 versus 1.4 +/- 0.5, P less than .005). These findings suggest that even though chemoprophylaxis reduces the incidence of persistent trophoblastic disease in patients at high risk, it increases tumor resistance and morbidity. Although prophylactic chemotherapy with methotrexate and citrovorum factor rescue may be helpful for high-risk patients who cannot be followed or whose compliance is in question, careful follow-up remains the most important way to identify patients who should receive chemotherapy.

Adult↗

Methotrexate treatment of unruptured ectopic pregnancy: a report of 100 cases.

In an ongoing clinical trial, 100 patients with an unruptured ectopic pregnancy of 3.5 cm or less in greatest dimension were treated with an outpatient protocol of methotrexate and citrovorum factor chemotherapy. Methotrexate and citrovorum were given on alternating days until the hCG titer had decreased by 15% on 2 consecutive days. The patients ranged in age from 16-40 years, gravidity from 1-8, and parity from 0-5. Twenty-three patients had a previous ectopic pregnancy. Of the 100 patients, 96 (96%) received methotrexate/citrovorum as primary therapy and four (4%) were treated for persistent hCG titers after a conservative surgical procedure. The tubal pregnancies of patient nos. 1-50 were confirmed by laparoscopy, whereas patient nos. 51-100 were diagnosed according to a nonlaparoscopic algorithm. Four patients of 100 failed medical therapy and required surgery. Of these, one had an ectopic pregnancy with cardiac activity, one ruptured after intercourse, and the remaining two cases had no specific identifiable risk factors. Of the ectopic pregnancies with cardiac activity, 80% were successfully treated. Five patients (5%) had methotrexate-related side effects, all after the fourth dose, but none required treatment for these side effects. Hysterosalpingograms done on 58 patients subsequently demonstrated tubal patency in 84.5% on the involved side. To date, 37 pregnancies have occurred in this group, of which 31 (89.2%) were intrauterine and four (10.8%) were recurrent ectopic pregnancies. We conclude that methotrexate/citrovorum is safe, effective, and helps to preserve reproductive performance when used as primary therapy for unruptured ectopic pregnancy and for treatment of persistent disease following a conservative surgical procedure.

Adolescent↗

Nutrition of the European corn borer, Pyrausta nubilalis (HBN). III. An unidentified dietary factor required for larval growth.

1. The European corn borer larva has been shown to require a dietary source of one or more unidentified factors contained in corn leaves, grass juice concentrate, and certain other plant materials. The required factor or factors has been termed the corn leaf factor. 2. The corn leaf factor does not appear to be identical with any of the known B vitamins, or with ascorbic acid, sodium nucleate, citrovorum factor, or carnitine. 3. The corn leaf factor is heat-stable, acid-stable, water-soluble, and dialyzable.

Animals↗