Pharmacogenomics of genes involved in antifolate drug response and toxicity in osteosarcoma.

INTRODUCTION: Antifolates are structural analogs of folates, which have been used as antitumor drugs for more than 60 years. The antifolate drug most commonly used for treating human tumors is methotrexate (MTX), which is utilized widely in first-line treatment protocols of high-grade osteosarcoma (HGOS). In addition to MTX, two other antifolates, trimetrexate and pemetrexed, have been tested in clinical settings for second-line treatment of recurrent HGOS with patients unfortunately showing modest activity. Areas covered: There is clinical evidence which suggsest that, like other chemotherapeutic agents, not all HGOS patients are equally responsive to antifolates and do not have the same susceptibility to experience adverse drug-related toxicities. Here, we summarize the pharmacogenomic information reported so far for genes involved in antifolate metabolism and transport and in MTX-related toxicity in HGOS patients. Expert opinion: Identification and validation of genetic biomarkers that significantly impact clinical antifolate treatment response and related toxicity may provide the basis for a future treatment modulation based on the pharmacogenetic and pharmacogenomic features of HGOS patients.

The protection against trimetrexate cytotoxicity in human bone marrow by sequence-dependent administration of raloxifene, 5-fluorouracil/trimetrexate.

BACKGROUND: Currently, one of the most effective strategies for the treatment and prevention of breast cancer is the use of drugs that block estrogen action in the breast. The success of the first clinically relevant selective estrogen receptor modulator (SERM), tamoxifen, provided the foundation for further testing of this drug to reduce breast cancer incidence in high-risk women. However, the negative effects associated with the long-term use of tanrhoxifen have initiated the search for compounds that are more effective but less toxic. The discovery of raloxifene (RAL), which functions as a potent antiestrogen in the breast but an estrogen receptor (ER) agonist in the bone and cardiovascular system with very little uterotropic activity, provided an alternative strategy to the targeted use of tamoxifen. The aim of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU)/trimetrexate (TMX) to determine the most effective regimes and cellular mechanism of action to mitigate trimetrexate cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: The cell viability was performed using the Quick Cell Proliferation Assay by exposing the cells to TMX, 5-FU and RAL alone; RAL 24 h prior to 5-FU followed 2 h by TMX, and 5-FU 2 h prior to TMX followed 24 h by RAL determined the sequence-dependent interaction between TMX, 5-FU and RAL on the proliferation. RESULTS: The growth rate in MCF-7 in late RAL was 34.75 +/- 4.79% of the control, whereas in bone marrow the same drug combination exhibits a significant protection against TMX cytotoxicity with late RAL yielding 51.25 +/- 4.43% of the control. The findings were also supported by Cell flow cytometry and Western blot analysis. CONCLUSION: Sequence-dependent administration of RAL in combination with 5-FU/TMX can act against TMX toxicity in human bone marrow, while not affecting the maximum inhibitory effect of TMX in breast cancer.

Thymidine and hypoxanthine protection patterns of the folic acid-enhanced synergies for combinations of trimetrexate plus a polyglutamylatable inhibitor of purine or thymidylate synthesis against human ileocecal HCT-8 cells.

In order to examine the intracellular locus of the folic acid (PteGlu)-enhanced synergies of trimetrexate (TMQ) plus the thymidylate synthase (TS) inhibitor, raltitrexed (RTX), and TMQ plus the glycinamide ribonucleotide formyltransferase (GARFT) inhibitor, AG2034, comprehensive protection studies with thymidine (dThd) and hypoxanthine (HX) were conducted in a 96-well plate cell growth inhibition (sulforhodamine B) assay. Current modeling techniques were extended to characterize these protection patterns involving multiple-agent interaction. Wild-type human ileocecal HCT-8 cells and DW2, a subline deficient in folylpoly-gamma-glutamate synthetase (FPGS) were individually treated for 96 h with TMQ, AG2034 and a 1:1 mixture of TMQ:AG2034 or with TMQ, RTX, and a 1:1 mixture of TMQ:RTX in the presence of PteGlu (2.3 or 40 micro M) and the protection agents (10 micro M dThd and/or 100 micro M HX). Drug treatments were randomly assigned to wells. Both isobols and 3-dimensional concentration-effect surfaces were used to assess the nature and the intensity of drug interactions. The structural Hill model was fitted to data with weighted non-linear regression for most cases. A so-called 'double Hill' model was sometimes more appropriate when a plateau in the middle of the concentration-effect curve was found. In HCT-8 and DW2 cells at 2.3 and 40 micro M PteGlu, inhibition of DHFR by TMQ induced antithymidylate and antipurine effects; AG2034 and RTX selectively inhibited de novo purine or thymidine synthesis, respectively. dThd protection increased the PteGlu-enhancement of the TMQ + AG2034 synergy, whereas HX protection increased the PteGlu-enhancement of the TMQ + RTX synergy. The PteGlu-enhanced synergies of TMQ + AG2034 and TMQ + RTX occur primarily through inhibition of purine synthesis and inhibition of thymidylate synthesis, respectively. These results further substantiate the hypothesis that the nonpolyglutamylatable DHFR inhibitor, TMQ, acts as a modulator by decreasing the protection by PteGlu of cells against the polyglutamylatable AG2034 and RTX.

Trimetrexate in relapsed T-cell lymphoma with skin involvement.

PURPOSE: Methotrexate (MTX) is active against lymphomas, but transport or polyglutamylation mutations confer MTX resistance. Because trimetrexate (TMTX) enters cells by passive diffusion and is not polyglutamylated, its activity in relapsed T-cell lymphoma was investigated. PATIENTS AND METHODS: Eligible patients had histologically confirmed relapsed T-cell lymphoma involving the skin, had received more than one previous regimen, were older than 16 years, had normal organ function, and had no CNS disease or serious infections, including human immunodeficiency virus. TMTX (200 mg/m(2)) was given intravenously every 14 days without topical or systemic corticosteroids. Patients who responded received up to 12 doses. RESULTS: Twenty patients were assessable for response. Median age was 59 years (range, 45 to 87 years); 13 patients were men. Three patients had anaplastic large-cell lymphoma, 15 had mycosis fungoides or Sézary syndrome (14 with large-cell transformation), and two had peripheral T-cell lymphoma. Serum lactate dehydrogenase was high in 35%, and beta-2 microglobulin was more than 3.0 mg/L in 35% of patients. The median number of previous regimens was three (range, two to 15) and included MTX in five patients. Disease was refractory to the regimen immediately preceding TMTX in 85% of patients. Responses were complete in one and partial in eight patients (overall response rate, 45%). Two of five patients previously treated with MTX responded. Grade 3 or 4 mucositis was observed after 4%, infection after 3%, neutropenic fever after 6%, neutrophils less than 100/microL after 4%, and platelets less than 10,000/microL after 3% of TMTX doses. CONCLUSION: TMTX is active with acceptable toxicity in this population and merits further investigation.

Phase II evaluation of oral trimetrexate in mixed mesodermal tumors of the uterus: a gynecologic oncology group study.

OBJECTIVES: This is a Phase II group-wide study of the Gynecologic Oncology Group to determine the toxicity and objective response rate of trimetrexate (TMTX) in patients with advanced, persistent, or recurrent mixed mesodermal tumors of the uterus who have failed higher priority treatment protocols. METHODS: TMTX was administered orally at a dose of 5 mg/m(2) BID for 5 days and repeated in 14 days. The maximum total dose was 50 mg/m(2)/week given every other week. The minimum treatment period was one course. Patients who had a complete response, partial response, or stable disease were continued on treatment for at least three courses. RESULTS: Twenty-eight patients were entered into the study. Three patients were ineligible based on review of pathologic materials. Twenty-five patients were evaluable for toxicity, and 21 were evaluable for response, as 4 patients did not complete one course of therapy. Eleven patients had heterologous mixed mesodermal tumor (MMT) and 10 had homologous MMT. Of the 25 evaluable for toxicity, one patient had grade 4 platelet toxicity. No patient had grade 4 neutropenia, while 4 patients had grade 3 decrease in absolute neutrophil count. One patient had grade 3 gastrointestinal toxicity, while 2 had grade 4 toxicity. There were no complete responses noted and only one partial response, for an overall response rate of 4.8%. The duration of the partial response was 15.2 months. CONCLUSION: Oral TMTX has insignificant activity in the treatment of advanced, persistent, and recurrent uterine MMT at the dose and schedule administered.

A double-blind placebo-controlled randomized phase III trial of 5-fluorouracil and leucovorin, plus or minus trimetrexate, in previously untreated patients with advanced colorectal cancer.

BACKGROUND: Trimetrexate (TMTX) biochemically modulates 5-fluorouracil (5-FU) and leucovorin (LCV). Two phase II trials demonstrated promising activity for TMTX/5-FU/LCV in patients with untreated advanced colorectal cancer (ACC). This trial was designed to demonstrate the safety and efficacy of TMTX/5-FU/LCV as first-line treatment in ACC. PATIENTS AND METHODS: Eligible patients with ACC were randomized in double-blind fashion to receive placebo or TMTX (110 mg/m2) intravenously (i.v.) followed 24 h later by i.v. LCV 200 mg/m2, and 5-FU 500 mg/m2 plus oral LCV rescue. Both schedules were given weekly for 6 weeks every 8 weeks. Patients were evaluated for progression-free survival (PFS), overall survival (OS), tumor response, quality of life (QoL) and toxicity. RESULTS: A total of 382 eligible patients were randomized. Significant toxicities were noted more frequently with TMTX/5-FU/LCV. Diarrhea was the most common grade 3 or 4 side-effect (41% and 28% on the TMTX and placebo arms, respectively). QoL scores and response rates did not differ between treatment arms. PFS was 5.3 months and 4.4 months in the TMTX and placebo arms, respectively (P = 0.77; Wilcoxon). OS was 15.8 months and 16.8 months, respectively (P = 0.73; Wilcoxon). CONCLUSIONS: The addition of TMTX to a weekly regimen of 5-FU/LCV worsened grade 3 or 4 diarrhea. The inclusion of TMTX did not yield any significant improvements in response rate, PFS or OS.

Trimetrexate as biochemical modulator of 5-fluorouracil/leucovorin in advanced colorectal cancer: final results of a randomised European study.

BACKGROUND: Trimetrexate (TMTX) is a biochemical modulator of 5-fluorouracil (5-FU) and leucovorin (LV). Phase II trials have shown promising activity of 5-FU/LV/TMTX in patients with advanced colorectal cancer (ACC). This trial evaluated the effect of TMTX in combination with 5-FU/LV as first-line treatment in ACC. PATIENTS AND METHODS: Patients with ACC were randomised to receive either intravenous LV 200 mg/m2/5-FU 600 mg/m2 or TMTX 110 mg/m2 followed 24 h later by LV 200 mg/m2/5-FU 500 mg/m2 plus oral LV rescue. Both schedules were given weekly for 6 weeks every 8 weeks. Patients were evaluated for progression-free survival (PFS), overall survival (OS), tumour response, quality of life (QoL) and toxicity. RESULTS: A total of 365 patients were randomised. A statistically significant prolongation of median PFS was seen in patients treated with TMTX/5-FU/LV compared with 5-FU/LV (5.4 months versus 4.1 months, respectively; P = 0.03), and a trend towards a significant benefit for OS (13.4 months versus 10.5 months, respectively; P = 0.08). Tumour response, QoL and toxicity were comparable between the two arms. Diarrhoea was the most frequently occurring grade 3 or 4 toxicity (22% and 30%, respectively). CONCLUSIONS: The addition of TMTX to a weekly regimen of 5-FU/LV results in a small but significant improvement in PFS without adding toxicity or worsening QoL in patients with ACC.

Trimetrexate in the treatment of recurrent or advanced leiomyosarcoma of the uterus: a phase II study of the Gynecologic Oncology Group.

OBJECTIVE: This study was conducted to determine the objective response of trimetrexate in patients with advanced or recurrent leiomyosarcoma of the uterus. METHODS: Eligibility was restricted to patients with measurable disease who had received no more than one prior chemotherapy regimen, who had adequate bone marrow, renal, and hepatic function, and who had recovered from previous therapy. Trimetrexate was begun at 5 mg/m2/day orally for 5 days every other week, with dose modifications specified by study design. RESULTS: Of 28 patients entered into the study, 27 were evaluable for toxicity and 23 for response. Prior therapy included radiation (7 patients) and/or chemotherapy (10 patients). Measurable disease was extrapelvic in 20 cases and confined to the pelvis in 3. The overall response rate was 4.3%; there were no complete responses and 1 partial response. Toxicities were mild to moderate with no treatment-related deaths. Hematological toxicity was most common, consisting of leukopenia (grade 1 to 2, 8 patients; grade 3 or 4, 2 patients), thrombocytopenia (grade 1 to 2, 10 patients; grade 3 or 4, 1 patient), and anemia (grade 1 to 2, 6 patients; grade 3 or 4, 4 patients. Severe (grade 3 or 4) nonhematologic toxicity was uncommon: nausea/vomiting/gastrointestinal (3 patients) and neurological (1 patient). Progression-free and overall survival, in months, was 2.2 (range: 0.9-13.4) and 7.2+ (range: 1.0-13.4+), respectively. CONCLUSION: Although toxicity is acceptable, trimetrexate at this dose and schedule is ineffective therapy for patients with recurrent leiomyosarcoma. Further development of this specific regimen for this indication is unwarranted.

Sequential trimetrexate, 5-fluorouracil and folinic acid are effective and well tolerated in metastatic colorectal carcinoma. The phase II study group of the AIO.

Trimetrexate (TMTX) is a new antifolate which avoids competition for cellular uptake with folinic acid (FA). A regimen of sequential TMTX, FA and 5-fluorouracil (5-FU) has shown efficacy in patients with colorectal cancer. Therefore, we treated 34 previously untreated patients with metastatic colorectal cancer with a weekly chemotherapy regimen consisting of 110 mg/m(2) of TMTX intravenously, then 24 h later 200 mg/m(2) of FA (i.v.) and 500 mg/m(2) of 5-FU (i. v.). Thereafter, 7 doses of oral FA (15 mg) were given at 6-hourly intervals. A treatment cycle consisted of 6 weeks of treatment, then 2 weeks of rest. All patients were treated as outpatients unless complications arose. Thirty-three patients were assessable for tumor response, and all 34 patients were assessable for toxicity. Twelve patients (36%; 95% confidence interval: 25-49%) achieved a partial response. The median duration of response was 8.5 months, and median survival was 14 months. The most common toxicity was diarrhea of grade 3/4, observed in 22% of treatment cycles; this decreased to 8% with early loperamide treatment. Hematologic toxicity was mild. The sequential administration of TMTX, FA and 5-FU is an active regimen in the first-line treatment of metastatic colorectal cancer and warrants further studies.

Phase II trial of trimetrexate for patients with advanced gastric carcinoma: an Eastern Cooperative Oncology Group study (E1287).

BACKGROUND: A Phase II study was conducted to evaluate the response, duration of response, and duration of survival of patients with measurable gastric carcinoma treated with trimetrexate (TMTX) who had not had prior chemotherapy. METHODS: Thirty-three patients with unresectable or metastatic gastric adenocarcinoma who had not received previous chemotherapy were treated with intravenous TMTX 12 mg/m(2) daily for 5 days. The dosage of TMTX was reduced to 8 mg/m(2) daily for 5 days for those who had received prior radiotherapy. The cycle was repeated every 3 weeks until disease progression or unacceptable toxicity occurred. RESULTS: Thirty-three patients could be analyzed with follow-up data. There was one Grade 5 (lethal) toxicity and four Grade 4 toxicities. Hematologic toxicity was the most common. The overall response rate was 21%, the overall median progression free survival was 2.7 months, and the overall median survival was 5.9 months for the entire cohort. No patients were alive at last follow-up. CONCLUSIONS: Though TMTX as a single agent has activity in gastric carcinoma with manageable toxicity, it cannot be recommended for routine use as a single agent due to the brief duration of response and median survival.

High-dose trimetrexate and minimal-dose leucovorin: a case for selective protection?

Our objective was to find the minimum dose of leucovorin (LV; 5-formyltetrahydrofolate) needed to potentially provide selective protection of normal tissue in patients with tumors resistant to methotrexate (MTX) by virtue of transport during prolonged therapy with high-dose trimetrexate (TMTX). Based upon the known daily requirement for folate, that tumors are often resistant to methotrexate via a transport-based mechanism, and that large doses of trimetrexate can be given with large doses of leucovorin for the treatment of patients with Pneumocystis carinii, a protocol was designed to find the minimum LV dose required to allow the administration of large doses of TMTX. Patients were treated in 28-day cycles consisting of 14 consecutive days of oral TMTX (45 mg/m2 every 12 h), followed by 14 days of rest. The dose of concurrent LV was started at 5 mg/m2 twice daily. Cohorts of patients received successive half doses of LV so long as three consecutive patients had less than or equal to grade 3 toxicity. Ten patients received 29 courses of therapy. The most common toxicities encountered were thrombocytopenia (38%), mucositis (14%), and neutropenia (10%). At a LV dose of 2.5 mg/m2, toxicities were consistently limited to less than or equal to grade 3 and only one episode of grade 4 hematological toxicity. Although there was marked interpatient variability, the minimally effective LV dose for selective protection seems to be 2.5 mg/m2. If tumors are resistant to methotrexate because of decreased transport of drug (and also folate), then the same pharmacological principle used to develop TMTX/LV for the treatment of P. carinii may be applied to treatment of some patients with cancer.

A randomized phase II trial of echinomycin, trimetrexate, and cisplatin plus etoposide in patients with metastatic nonsmall cell lung carcinoma: an Eastern Cooperative Oncology Group Study (E1587).

BACKGROUND: Patients with metastatic nonsmall cell lung carcinoma (NSCLC) usually have a poor prognosis. A chemotherapy regimen containing cisplatin is commonly used for symptom palliation. Echinomycin is a potent bifunctional intercalator of double-strand DNA; trimetrexate is a new derivative of methotrexate and is active against methotrexate-resistant tumor cells in vitro. METHODS: The Eastern Cooperative Oncology Group conducted a randomized Phase II study. Eligible patients were assigned to receive echinomycin 1200 microg/m2 by intravenous (i.v.) infusion over 30-60 minutes once a week for 4 weeks, repeated every 6 weeks; trimetrexate 12 mg/m2 i.v. bolus on Days 1-5 every 3 weeks, or 8 mg/m2 i.v. bolus on Days 1-5 for patients who had prior radiation to greater than 30% of their bone marrow; or cisplatin 60 mg/m2 i.v. on Day 1 and etoposide 120 mg/m2 i.v. on Days 1-3 every 4 weeks. Patients were evaluated before each cycle for tumor response, toxicity, and quality-of-life measurements. RESULTS: One hundred thirty-six patients were entered on the study, and 118 were evaluable for toxicity and response. The response rates were 16%, 5%, and 5% in patients treated with cisplatin and etoposide, echinomycin, and trimetrexate, respectively. There were no complete responses. The median survival was 37.9, 24.3, and 28.0 weeks for patients who received cisplatin and etoposide, echinomycin, and trimetrexate, respectively. Although cisplatin and etoposide appeared to give better therapeutic results, the response rate or survival did not reach statistical significance. This may have been due to inadequate sample size. Neither did quality-of-life measurement show any significant differences among treatments. CONCLUSIONS: Echinomycin and trimetrexate had minimal antitumor activity in patients with metastatic NSCLC: Response rate and survival remained poor in all three treatment arms. Patients should be encouraged to participate in clinical trials so that more effective therapy can be identified.

A bicistronic retroviral vector for protecting hematopoietic cells against antifolates and P-glycoprotein effluxed drugs.

Chemoresistance gene transfer is an experimental method to protect hematopoietic cells from the toxicity of anticancer drugs. Because multiple drugs are usually given together in cancer therapy, this strategy will ultimately require vectors expressing multiple chemoresistance genes. For this reason, we designed a bicistronic retroviral vector (HaMID) containing a modified human multidrug resistance-1 cDNA and a mutant human dihydrofolate reductase cDNA bearing a leucine to tyrosine substitution at codon 22 (L22Y). To determine if this vector would confer dual drug resistance to hematopoietic cells, recombinant retrovirus was used to transduce the human CEM T lymphoblastic cell line as well as primary murine myeloid progenitors. Growth suppression assays, using polyclonal transduced CEM cells, demonstrated increased resistance to taxol (13-fold), trimetrexate (8.9-fold), vinblastine (5.6-fold), methotrexate (2.5-fold), and etoposide (1.5-fold) when used as single agents. HaMID-transduced cells also grew at a logarithmic rate in the simultaneous presence of 25 nM taxol and 100 nM trimetrexate while control cells were entirely growth inhibited by this drug combination. Similarly, HaMID-transduced murine myeloid progenitors acquired increased resistance to taxol (2.9-fold) and trimetrexate (140-fold), and were able to form colonies in the simultaneous presence of both drugs. Our results suggest that retroviral transfer of HaMID into primary hematopoietic cells should reduce the myelosuppression associated with the combined use of antifolates and P-glycoprotein-effluxed drugs.

Phase II study of trimetrexate, fluorouracil, and leucovorin for advanced colorectal cancer.

PURPOSE: A phase II study to evaluate the response rate and toxicities of a trimetrexate, fluorouracil (5FU), and leucovorin regimen in patients with advanced incurable colorectal cancer. PATIENTS AND METHODS: Thirty-six patients with unresectable or metastatic colorectal cancer who had not been treated for advanced disease received the following chemotherapy regimen weekly for six courses every 8 weeks: trimetrexate 110 mg/m2 intravenously (I.V.) on day 1, leucovorin 200 mg/m2 I.V. on day 2 (24 hours later), 5FU 500 mg/m2 on day 2 immediately following leucovorin, and oral leucovorin 15 mg every 6 hours for seven doses starting 6 hours after 5FU. Patients were treated until progression or unacceptable toxicity. RESULTS: Thirty patients were assessable for response, and all 36 were assessable for toxicity. Two patients (7%) achieved a complete response (CR) and 13 (43%) a partial response (PR), for an overall response (OR) rate of 50% (95% confidence interval [CI], 32% to 68%). Analysis by intent to treat demonstrated a 42% OR rate (95% CI, 26% to 58%). At final analysis, 16 patients were alive. The median survival duration for the entire cohort was 53.4 weeks. Gastrointestinal toxicity was most common, with 21 patients (58%) having grade 3/4 diarrhea and 12 patients (34%) grade 3/4 nausea. Hematologic toxicity was generally low grade, although two patients died of sepsis. CONCLUSION: The combination of trimetrexate with 5FU and leucovorin is active in metastatic colorectal cancer. Gastrointestinal toxicity with this regimen is most prominent, but is manageable.

The hematological effects of folate analogs: implications for using the dihydrofolate reductase gene for in vivo selection.

Previous studies have shown that dihydrofolate reductase (DHFR) gene transfer protects marrow from methotrexate (MTX)-mediated toxicity; however, MTX treatment in vivo has not convincingly been shown to enrich DHFR-transduced progenitors or stem cells. Experiments were performed to better characterize the hematological effects of MTX, and maneuvers were tested with the aim of improving the utility of MTX as an agent for in vivo selection. Progenitors were assayed as colony forming unit cells in culture (CFU-C) and in the spleens of irradiated mice (day 11 CFU-S). A single injection of MTX at doses up to 250 mg/kg (more than three times the LD10) failed to reduce CFU-C numbers significantly in the femur or spleen assayed 1-3 days later. However, consistent declines in the number of mononuclear cells per femur reflected a significant depletion of nonclonogenic precursor cells. Preceding administration of pegylated stem cell factor (SCF), 100 micrograms/kg per day, increased CFU-C killing by a single dose of 5-fluorouracil (5-FU) 15- to 65-fold in the femur, and 5- to 15-fold in the spleen, consistent with previous reports. In contrast, despite preceding SCF administration there was no significant progenitor killing by MTX. Similar results were obtained using a second folate analog, trimetrexate. These results suggest that the mechanism by which folate analogs exert their hematological toxicity is through the depletion of relatively mature, nonclonogenic precursor cells, and not by killing progenitors. This information is relevant to the use of DHFR in gene therapy protocols, and suggests that folate analogs are poorly suited agents for selection at the level of clonogenic progenitor cells in vivo.

Phase II trial of trimetrexate in advanced esophageal cancer: a southwest oncology group study.

Trimetrexate (TMQ) is a synthetic folate antagonist that has demonstrated non-cross resistance with methotrexate in preclinical screens. A phase II trial was performed with TMQ given to patients with advanced squamous cell carcinoma of the esophagus. TMQ was administered as an i.v. bolus on a daily x 5 schedule, every 3 weeks; a starting dose of 12 mg/m2 was used for patients with no prior irradiation, and of 8 mg/m2 for patients with prior irradiation. Twenty-four patients were entered onto study, with 23 patients eligible, and a median of 2 courses of TMQ administered per patient. Twenty-three patients were evaluable for toxicity. Toxicities of SWOG grade > or = 3 included granulocytopenia (9 patients), leukopenia (7 patients), thrombocytopenia (4 patients), anemia (3 patients), mucositis (3 patients), nausea and vomiting (2 patients), dermatitis (1 patient), diarrhea (1 patient), and fever (1 patient). Fifteen patients had some hematologic toxicity, and eleven patients had hematologic toxicity of grade > or = 3. Two treatment related deaths occurred in association with myelosuppression. One patient achieved a complete response and one patient achieved a partial response, with response durations of 8.5 months and 6 months, respectively. The overall response rate was 8% [95% confidence interval of 1 to 28%], with a median survival for the 23 eligible patients of 5.1 months.

A toxicity study of trimetrexate used in combination with cyclosporine as acute graft-versus-host disease prophylaxis in HLA-mismatched, related donor bone marrow transplants.

This study evaluated the acute toxicity of trimetrexate (TMTX) used in combination with cyclosporine (CsA) for prevention of acute graft-versus-host disease (GVHD) in patients undergoing allogeneic marrow transplantation from HLA-mismatched, related donors. TMTX has a mechanism of action similar to that of methotrexate (MTX); however, unlike MTX, TMTX is not primarily dependent on renal excretion. Patients were conditioned for transplant with cyclophosphamide, anti-thymocyte globulin, and total body irradiation. TMTX, 10 mg/m2 i.v., was administered on days 1, 3, 6, 11, 18, 25, 32, and 39 after transplant. CsA, 1.5 mg/kg i.v., was administered every 12 hr beginning on day-1. Eleven patients with hematologic malignancies or aplastic anemia (median age = 34 yr) received TMTX. Toxicity assessed included nausea, vomiting, fever, rash, time to myeloid and platelet engraftment, mucositis, and hepatic and renal dysfunction. Toxicity of TMTX was not different from that observed with MTX in a similar patient population. One patient died on day 16 before engraftment. The other 10 patients all engrafted and all developed acute GVHD at a median time of 11 days after transplant. The major manifestation of acute GVHD was in the skin, and all but one patient responded to primary therapy with corticosteroids. Seven patients have survived a median of 447 days after transplant. No significant toxicity from TMTX was observed. Further trials are warranted to define the role of TMTX in marrow transplantation.

Dosing guidelines for foscarnet and trimetrexate.

The P & T Committee at Trinity Lutheran Hospital, a 320-bed, community/teaching hospital in Kansas City, MO, has developed dosing and monitoring guidelines for foscarnet sodium (Foscavir) and trimetrexate glucuronate (Neutrexin)--two drugs used to treat patients with opportunistic infections associated with the human immunodeficiency virus (HIV). Presented in this Experience Brief is a short discussion of these drugs, the rationale for guideline development, and the actual dosing and monitoring protocols devised.

A randomized trial of two schedules of trimetrexate versus 5-fluorouracil in advanced colorectal cancer: a Southwest Oncology Group study.

Trimetrexate (TMQ), a non-classical folate antagonist, was studied in a randomized controlled trial in patients with advanced colorectal cancer and without prior chemotherapy. Patients were randomly assigned to one of three treatments: TMQ at 200 mg/m2 i.v. q 2 weeks, TMQ at 12 mg/m2 i.v. daily x 5 or 5-fluorouracil (5-FU) at 15 mg/kg i.v. weekly. Overall response rates were: 6% (four partial responses in 71 patients, 95% CI of 2-14%) for q 2 week TMQ, 0% (zero of 29, 95% CI of 0-29%) for daily x 5 TMQ and 18% (two complete and nine partial responses in 62 patients, 95% CI of 9-30%) for 5-FU. Median survival estimates were 10.3 months for the q 2 week TMQ schedule, 8.7 months for the daily x 5 TMQ schedule and 13.6 months for the 5-FU schedule. Grade < or = 3 toxicities were significantly more common with TMQ. TMQ does not appear to have significant antitumor activity against colorectal cancer.