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PubMed2004

Schedule-dependent synergism and antagonism between pemetrexed and paclitaxel in human carcinoma cell lines in vitro.

Pemetrexed is a novel multitargeted antifolate with significant clinical activity against a variety of tumors. We studied the schedule-dependent cytotoxic effects of pemetrexed in combination with paclitaxel in vitro to improve our understanding of how this combination might be used clinically. Human lung cancer A549 cells, breast cancer MCF7, ovarian cancer PA1, and colon cancer WiDr cells were exposed to both pemetrexed and paclitaxel in vitro. Cell growth inhibition after 5 days was determined and the effects of drug combinations were analyzed by the isobologram method (Steel and Peckham). Simultaneous exposure to pemetrexed and paclitaxel for 24 h produced antagonistic effects in A549 and PA1 cells, additive/antagonistic effects in MCF7 cells, and additive effects in WiDr cells. Pemetrexed for 24 h followed by paclitaxel for 24 h produced synergistic effects in A549 and MCF7 cells and additive effects in PA1 and WiDr cells, while the reverse sequence produced additive effects in all four cell lines. Cell cycle analysis supported these observations. Our findings suggest that the simultaneous administration of pemetrexed and paclitaxel is suboptimal. The optimal schedule of pemetrexed in combination with paclitaxel is the sequential administration of pemetrexed followed by paclitaxel, and this schedule should be assessed in clinical trials for the treatment of solid tumors.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

A phase I/II study of pemetrexed and vinorelbine in patients with non-small cell lung cancer.

PURPOSE: Pemetrexed and vinorelbine are active antineoplastic agents in non-small cell lung cancer (NSCLC). Phase I objectives include maximum tolerated dose (MTD) and recommended phase II dose determination, and pharmacokinetics of the pemetrexed-vinorelbine doublet in locally advanced or metastatic solid tumor patients (pts). Phase II objectives include tumor response evaluation, efficacy, and toxicity for first-line treatment of advanced NSCLC. EXPERIMENTAL DESIGN: Phase I pts received pemetrexed (day 1, 300-700 mg/m2) and vinorelbine (days 1 and 8, 15-30 mg/m2) every 21 days. Pharmacokinetics determined at cycle 1. Beginning with dose-level 3, folic acid and Vitamin B12 supplementation were given. RESULTS: Thirty-one phase I pts were enrolled. MTD was pemetrexed 700 mg/m2 and vinorelbine 30 mg/m2; and recommended phase II dose was pemetrexed 500 mg/m2 and vinorelbine 30 mg/m2. When administered in combination, pemetrexed and vinorelbine pharmacokinetics were consistent with single-agent administration. Thirty-seven (36 chemonaive) phase II NSCLC pts received pemetrexed-vinorelbine. Evaluable tumor response was 40%, with intent-to-treat 38%. One drug-related death occurred from febrile neutropenia with Staphylococcal infection. Grade 3/4 hematologic toxicities were neutropenia (65%) and febrile neutropenia (11%), while prevalent grade 3/4 non-hematologic toxicity was fatigue (27%). CONCLUSION: The pemetrexed-vinorelbine combination is well tolerated and shows activity as first-line treatment in advanced NSCLC patients.

Adult↗
PubMed2003

Decreased expression of the reduced folate carrier and folypolyglutamate synthetase is the basis for acquired resistance to the pemetrexed antifolate (LY231514) in an L1210 murine leukemia cell line.

Pemetrexed (LY231514) is a new-generation antifolate that, in its polyglutamyl forms, is a potent inhibitor of thymidylate synthase and glycinamide ribonucleotide formyltransferase (GAR transformylase). This study explored the mechanisms of resistance to pemetrexed in L1210 murine leukemia cells using chemical mutagenesis with 5-formyltetrahydrofolate (5-formylTHF) as the growth substrate. A cell line, MTA-13, was identified that was 8.5-fold resistant to pemetrexed with comparable cross-resistance to ZD1694 (Tomudex) and lesser cross-resistance (5-fold) to ZD9331 [(2S)-2-(O-fluoro-p-[N-(2,7-dimethyl-4-oxo-3,4-dihydro-quinazolin-6-ylmethyl)-N-(prop-2-ynyl)amino]benzamido)-4-(tetrazol-5-yl)-butyric acid], DDATHF (dideazatetrahydrofolate) (3.5-fold), and methotrexate (MTX) (2.7-fold) but comparable sensitivity to trimetrexate. Influx of pemetrexed, MTX, and 5-formylTHF into MTA-13 cells was decreased by 56, 47, and 38% compared to wild-type cells. Folate receptor expression was negligible in both cell lines. Net drug uptake declined within 15min to a slower, constant rate over the next 45min, reflecting the rate of accumulation of pemetrexed polyglutamate derivatives. This rate in the MTA-13 line was half that of the wild-type cells. Accumulation of 50nM [3H]pemetrexed, 25nM [3H]5-formylTHF, or 50nM [3H]DDATHF after 3 days was decreased to 35, 46, and 56% the level of L1210 cells. The reduced folate carrier (RFC) message and protein were decreased by 50%, and folypolyglutamate synthetase (FPGS) message was decreased by 65% in MTA-13 cells. No mutations were detected in either protein by DNA sequence analysis. There was a slight decrease (approximately 25%) in thymidylate synthase mRNA, without mutations in the protein, and there was no change in GAR transformylase message. The data indicate that resistance to pemetrexed in the MTA-13 cell line was due to changes in both RFC and FPGS expression, two proteins that act in tandem to regulate polyglutamation of folates and antifolates in cells, resulting in cellular depletion of these active pemetrexed congeners.

Animals↗
PubMed2002

Pemetrexed in gastric cancer: clinical experience and future perspectives.

The development of more effective and convenient chemotherapy regimens for the treatment of gastric cancer that incorporate novel agents remains an exciting area of research. A phase II study was conducted to assess the response rate and toxicity profile of pemetrexed, a novel multitargeted antifolate, in previously untreated patients with measurable, advanced, or metastatic adenocarcinoma of the stomach or gastroesophageal junction. In this study, pemetrexed-induced toxicity at the starting dose of 500 mg/m(2) intravenously once every 21 days was considerable with each of the first six patients who experienced at least one episode of grade 3/4 toxicity. Two patients discontinued from study, and two patients died. All deaths were caused by drug-related toxicity. No responses were seen in this briefly treated group. These observations led to an amended study protocol designed to improve tolerability of pemetrexed with folic acid supplementation. Supplementation with folic acid 5 mg was given orally once daily for 2 days before pemetrexed on the day of treatment, and for 2 days following treatment. Tumor evaluation was performed after every two cycles of therapy. The trial was recently closed to accrual and preliminary clinical results are reported here. Thirty-two patients were enrolled and 30 patients were evaluable for efficacy. A total of 129 courses of pemetrexed were administered, and the median number of courses received per patient was four (range, one to eight courses). Two complete and five partial responses were observed, with four patients experiencing stable disease. In an intent-to-treat analysis, the overall response rate was 22%, and 23% for the evaluable patients. Median duration of response was 4.4 months (range, 3 to 11 months) and median time to treatment failure was 2.6 months (range, 0.5 to 12 months). Of the 32 patients treated, eight experienced grade 4 neutropenia and one had grade 4 thrombocytopenia. The most common nonhematologic toxicities were diarrhea, fatigue, mucositis, nausea and vomiting, skin rash, and reversible abnormalities in liver function. There was no case of nonhematologic grade 4 toxicity. Although the clinical experience with pemetrexed in advanced gastric cancer remains limited, the promising activity observed in this study indicates that combination studies are warranted. In addition, high-dose intermittent oral folic acid given in this study allowed administration of pemetrexed at the dose and schedule explored with a highly satisfactory safety profile and with no apparent compromise in efficacy. This article discusses how pemetrexed may be investigated in future clinical trials in gastric cancer.

Antimetabolites, Antineoplastic↗
PubMed2005

Cellular and pharmacogenetics foundation of synergistic interaction of pemetrexed and gemcitabine in human non-small-cell lung cancer cells.

Gemcitabine and pemetrexed are effective agents in the treatment of non-small-cell lung cancer (NSCLC), and the present study investigates cellular and genetic aspects of their interaction against A549, Calu-1, and Calu-6 cells. Cells were treated with pemetrexed and gemcitabine, and their interaction was assessed using the combination index. The role of drug metabolism in gemcitabine cytotoxicity was examined with inhibitors of deoxycytidine kinase (dCK), 5'-nucleotidase, and cytidine deaminase, whereas the role of pemetrexed targets, thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT) in drug chemosensitivity was analyzed in cytotoxicity rescue studies. The effect of gemcitabine and pemetrexed on Akt phosphorylation was investigated with enzyme-linked immunosorbent assay, whereas quantitative polymerase chain reaction (PCR) was used to study target gene-expression profiles and its modulation by each drug. Synergistic cytotoxicity was demonstrated, and pemetrexed significantly decreased the amount of phosphorylated Akt, enhanced apoptosis, and increased the expression of dCK in A549 and Calu-6 cells, as well as the expression of the human nucleoside equilibrative transporter 1 (hENT1) in all cell lines. PCR demonstrated a correlation between dCK expression and gemcitabine sensitivity, whereas expression of TS, DHFR, and GARFT was predictive of pemetrexed chemosensitivity. These data demonstrated that 1) gemcitabine and pemetrexed synergistically interact against NSCLC cells through the suppression of Akt phosphorylation and induction of apoptosis; 2) the gene expression profile of critical genes may predict for drug chemosensitivity; and 3) pemetrexed enhances dCK and hENT1 expression, thus suggesting the role of gene-expression modulation for rational development of chemotherapy combinations.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

A phase I study of pemetrexed (ALIMTA) and cyclophosphamide in patients with locally advanced or metastatic breast cancer.

PURPOSE: Determine the maximum tolerated dose (MTD) of pemetrexed and cyclophosphamide combination therapy for patients with locally advanced or metastatic breast cancer. EXPERIMENTAL DESIGN: Patients with locally advanced or metastatic breast cancer and WHO performance status 0 to 2 were eligible. Pemetrexed (range, 400-2,400 mg/m(2)) was administered on day 1 of a 21-day schedule followed by cyclophosphamide (range, 400-800 mg/m(2)). Folic acid and vitamin B(12) supplementation began 1 to 2 weeks before the first pemetrexed dose. RESULTS: Fifty-seven pretreated patients were enrolled and received 342 cycles (median, 4 cycles; range, 1-26) through 14 dose levels. The MTD of pemetrexed was 2,400 mg/m(2) (combined with cyclophosphamide, 600 mg/m(2)) with dose-limiting toxicities of grade 4 neutropenia with grade 4 infection and grade 3 diarrhea. Other grade 3 or 4 toxicities included (febrile) neutropenia, thrombocytopenia, anemia, elevated alanine aminotransferase/aspartate aminotransferase, and diarrhea. Pharmacokinetic analysis indicated that pemetrexed clearance and central volume of distribution were 40% lower than single-agent reference data, yielding a 68% increase in total systemic exposure and a 56% increase in maximal plasma concentration. Among the 50 patients evaluable for efficacy, 13 (26%) patients had a partial response and 17 (34%) patients had stable disease. CONCLUSIONS: Pemetrexed was generally well tolerated. The observed toxicities were consistent with the known toxicity profiles of pemetrexed and cyclophosphamide. Considering the MTD and the toxicity and efficacy results in this and prior studies, a low (600 mg/m(2)) and a high (1,800 mg/m(2)) dose of pemetrexed with cyclophosphamide (600 mg/m(2)) will be evaluated in the consecutive prospective randomized phase II study.

Adult↗
PubMed2006

The inverse relationship between reduced folate carrier function and pemetrexed activity in a human colon cancer cell line.

Pemetrexed, a new generation antifolate recently approved for the treatment of mesothelioma and non-small cell lung cancer, is an excellent substrate for the reduced folate carrier (RFC). To explore the carrier's effect on pemetrexed activity, RFC was inactivated in HCT-15 colon cancer cells by mutagenesis and PT632 selective pressure. A clone (PT1) was obtained with a glycine to arginine substitution at amino acid 401, resulting in the loss of RFC function. PT1 cells were resistant to PT632 (178-fold), methotrexate (4-fold), and ZD1694 (Tomudex, raltitrexed; 20-fold), but were 3-fold collaterally sensitive to pemetrexed when grown in 25 nmol/L of 5-formyltetrahydrofolate. PT1 cells transfected with wild-type RFC had antifolate sensitivities comparable to that of wild-type HCT-15 cells, indicating that the RFC mutation was the sole basis for resistance. Folate pools were contracted in PT1 cells by 32% or 60%, as measured by radiolabeling intracellular folates or by an enzyme binding assay, respectively. This was reflected in marked (6.5-fold) collateral sensitivity to trimetrexate. The initial uptake of pemetrexed in PT1 cells was markedly reduced ( approximately 85%) but intracellular pemetrexed levels increased to approximately 60% and approximately 70% to that of wild-type cells after 2 hours and 6 days, respectively. There was increased pemetrexed inhibition of glycinamide ribonucleotide transformylase and, to a lesser extent, thymidylate synthase in PT1 cells growing in 5-formyltetrahydrofolate based on nucleoside protection analyses. Hence, loss of RFC function leads to collateral sensitivity to pemetrexed in HCT-15 cells, likely due to cellular folate pool contraction resulting in partial preservation of pemetrexed polyglutamylation and increased target enzyme inhibition. micro

Amino Acid Substitution↗
PubMed2006

Phase I and pharmacokinetic study of pemetrexed administered every 3 weeks to advanced cancer patients with normal and impaired renal function.

PURPOSE: This phase I study was conducted to determine the toxicities, pharmacokinetics, and recommended doses of pemetrexed in cancer patients with normal and impaired renal function. PATIENTS AND METHODS: Patients received a 10-minute infusion of 150 to 600 mg/m2 of pemetrexed every 3 weeks. Patients were stratified for independent dose escalation by measured glomerular filtration rate (GFR) into four cohorts ranging from > or = 80 to less than 20 mL/min. Pemetrexed plasma and urine pharmacokinetics were evaluated for the first cycle. Patients enrolled after December 1999 were supplemented with oral folic acid and intramuscular vitamin B12. RESULTS: Forty-seven patients were treated with 167 cycles of pemetrexed. Hematologic dose-limiting toxicities occurred in vitamin-supplemented patients (two; 15%) and non-supplemented patients (six; 18%), and included febrile neutropenia (four patients) and grade 4 thrombocytopenia (two patients). Nonhematologic toxicities included fatigue, diarrhea, and nausea, and did not correlate with renal function. Accrual was discontinued in patients with GFR less than 30 mL/min after one patient with a GFR of 19 mL/min died as a result of treatment-related toxicities. Pemetrexed plasma clearance positively correlated with GFR (r2 = 0.736), resulting in increased drug exposures in patients with impaired renal function. With vitamin supplementation, pemetrexed 600 mg/m2 was tolerated by patients with a GFR > or = 80 mL/min, whereas patients with a GFR of 40 to 79 mL/min tolerated a dose of 500 mg/m2. CONCLUSION: Pemetrexed was well tolerated at doses of 500 mg/m2 with vitamin supplementation in patients with GFR > or = 40 mL/min. Additional studies are needed to define appropriate dosing for renally impaired patients receiving higher dose pemetrexed with vitamin supplementation.

Adult↗
PubMedDate not supplied

FDA drug approval summary: pemetrexed for injection (Alimta) for the treatment of non-small cell lung cancer.

On August 19, 2004, pemetrexed for injection (Alimta); Eli Lilly and Company, Indianapolis, IN, http://www.lilly.com) received accelerated approval as monotherapy for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) who had received prior chemotherapy. Approval was primarily based on a single, controlled, unblinded trial. Five hundred seventy-one protocol-eligible patients were randomized to receive either pemetrexed or docetaxel (Taxotere); Aventis Pharmaceuticals Inc., Bridgewater, NJ, http://www.aventispharmaus.com). The primary efficacy end point was overall survival. The median survival times were 8.3 months in the pemetrexed arm and 7.9 months in the docetaxel arm. Neither superiority nor noninferiority for overall survival could be demonstrated, the latter because a reliable and consistent survival effect of docetaxel could not be estimated and because of significant crossover of pemetrexed-treated patients to docetaxel after tumor progression. Comparable response rates, 9.1% for pemetrexed and 8.8% for docetaxel, times to progressive disease, and progression-free survival times supported the conclusion that an effect of pemetrexed on survival was reasonably likely, however. In addition, pemetrexed was felt to have a more favorable safety profile than docetaxel. Of greatest importance, pemetrexed caused significantly less neutropenia, febrile neutropenia, neutropenic infections, and need for granulocyte/macrophage colony-stimulating factors.

Adult↗
PubMed2004

Pemetrexed in advanced colorectal cancer.

Pemetrexed (Alimta) shows single-agent activity in advanced colorectal cancer. In two phase II studies in which patients received pemetrexed at 600 mg/m2 or 500 mg/m2 as first-line treatment for metastatic disease, objective response rates were 15.4% and 17.2%. These trials were conducted prior to supplementation with folic acid and vitamin B12, which markedly decreased the frequency of hematologic toxicities of pemetrexed; routine supplementation is now included in all clinical trials of the agent. The marked improvement in toxicity and tolerance with vitamin supplementation suggests the need to reexamine optimal dosing in pemetrexed combination schedules. In a National Surgical Adjuvant Breast and Bowel Project phase II trial in 54 patients with previously untreated advanced colorectal cancer, pemetrexed at 500 mg/m2 plus oxaliplatin (Eloxatin) at 120 mg/m2 every 21 days with folic acid/vitamin B12 supplementation resulted in an objective response of 23%. Three additionalpatients (5.6%) had unconfirmed partial response (partial response at one visit), and 27 patients (50%) had stable disease. Median progression-free survival was 5.3 months and median duration of response was 5.7 months; median overall survival was approximately 11.05 months. Grade 3/4 neutropenia was observed in only 17% of patients and treatment was well tolerated. A phase I/II study is under way to identify and assess the optimal combination of pemetrexed/irinotecan in second-line treatment of advanced colorectal cancer. Planned studies include a phase I study examining the combination of pemetrexed and oxaliplatin given every 2 weeks as first-line treatment, and a phase I/II trial to identify the optimal pemetrexed/ oxaliplatin dose in a 21-day schedule and to compare pemetrexed/ oxaliplatin with FOLFOX4 in first-line treatment of metastatic disease. All of these trials include vitamin supplementation. A phase III trial comparing the every-3-week pemetrexed/oxaliplatin regimen with FOLFOX4 as first-line treatment will be initiated if the outcome of the phase II trial is encouraging.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Phase II study of pemetrexed disodium, a multitargeted antifolate, and cisplatin as first-line therapy in patients with advanced nonsmall cell lung carcinoma: a study of the National Cancer Institute of Canada Clinical Trials Group.

BACKGROUND: Pemetrexed disodium (Alimta [Eli Lilly and Company, Indianapolis, IN], LY231514, multitargeted antifolate) is a new multitargeted antifolate agent that inhibits multiple enzymes in the folate pathway. Phase II trials showed single-agent response rates of 16% and 23% in untreated patients with nonsmall cell lung carcinoma (NSCLC). This study was undertaken to determine the response to pemetrexed disodium given in combination with cisplatin. METHODS: Previously untreated patients were eligible if they had Stage IIIB or IV NSCLC, performance status 0, 1, or 2, adequate hematology and biochemistry and bidimensionally measurable lesions. Patients with brain metastases or neuropathy higher than Grade 2 were excluded. Pemetrexed disodium 500 mg/m(2) was given over 10 minutes, and cisplatin 75 mg/m(2) with hydration and mannitol diuresis was administered on Day 1 of each 21-day cycle. Dexamethasone 4 mg was taken orally once every 12 hours starting 24 hours before treatment and continuing for 6 doses after treatment. Four patients had detailed pemetrexed disodium pharmacokinetic analysis performed. RESULTS: Between May 1998 and June 1999, 31 patients were treated on the study. There were 20 males and 11 females; median age was 60 years (range, 35-75 years); there were 5 Stage IIIB, 26 Stage IV, 26 performance status 0 or 1, and 5 performance status 2. In 29 patients evaluable for response, there were 13 partial responses (PRs; overall response rate [ORR], 95%; confidence interval [CI]: 26-64%) of median duration 6.1 months (1.6-7.8 months). Three of four evaluable patients with performance status 2 achieved PR, and 11 of 24 evaluable Stage IV patients responded (ORR, 45.8% in Stage IV). Eighteen patients died. The median survival rate was 8.9 months (range, 1-15+ months). A total of 160 courses were delivered (median, 6 for both cisplatin and pemetrexed disodium). Grade 3 and 4 anemia was observed in 5 and 1 patients, respectively, and Grade 3 and 4 granulocytopenia in 7 and 4 patients, respectively. Grade 3 nausea and emesis occurred in only 2 patients, Grade 3/4 diarrhea in 3 patients, and 2 patients had Grade 3 motor neuropathy. Nine patients had Grade 2 infections, and there was one case of febrile neutropenia. Pharmacokinetic results showed C(max), clearance and V(ss) values to be similar to data from single-agent pemetrexed disodium given in the same dose. CONCLUSIONS: The combination of pemetrexed disodium and cisplatin is active against advanced NSCLC and is a well-tolerated convenient outpatient regimen. It deserves further study to compare it with other standard regimens for NSCLC.

Adult↗
PubMed2005

A semimechanistic-physiologic population pharmacokinetic/pharmacodynamic model for neutropenia following pemetrexed therapy.

PURPOSE: The objectives of these analyses were to (1) develop a semimechanistic-physiologic population pharmacokinetic/pharmacodynamic (PK/PD) model to describe neutropenic response to pemetrexed and to (2) identify influential covariates with respect to pharmacodynamic response. PATIENTS AND METHODS: Data from 279 patients who received 1,136 treatment cycles without folic acid or vitamin B12 supplementation during participation in one of eight phase II cancer trials were available for analysis. Starting doses were 500 or 600 mg pemetrexed per m2 body surface area (BSA), administered as 10-min intravenous infusions every 21 days (1 cycle). The primary analyses included 105 patients (279 cycles) for which selected covariates-including vitamin deficiency marker data (i.e., homocysteine, cystathionine, methylmalonic acid, and methylcitrate [I, II, and total] plasma concentrations)-were available. Classical statistical multivariate regression analyses and a semimechanistic-physiologic population PK/PD model were used to evaluate neutropenic response to single-agent pemetrexed administration. RESULTS: The timecourse of neutropenia following single-agent pemetrexed administration was adequately described by a semimechanistic-physiologic model. Population estimates for system-based model parameters (i.e., baseline neutrophil count, mean transit time, and the feedback parameter), which mathematically represent current understanding of the process and physiology of hematopoiesis, were consistent with previously reported values. The population PK/PD model included homocysteine, cystathionine, albumin, total protein, and BSA as covariates relative to neutropenic response. CONCLUSION: These results support the programmatic decision to introduce folic acid and vitamin B12 supplementation during pemetrexed clinical development as a means of normalizing patient homocysteine levels, thereby managing the risk of severe neutropenia secondary to pemetrexed administration. The current results also suggest that the addition of vitamin B6 supplementation to normalize patient cystathionine levels may further decrease the incidence of grade 4 neutropenia following pemetrexed administration. The results also suggest the use of folic acid as a means of lessening hematologic toxicity following administration of cytotoxic agents other than antifolates.

Adult↗
PubMed2006

Plasma and cerebrospinal fluid pharmacokinetics of pemetrexed after intravenous administration in non-human primates.

PURPOSE: Pemetrexed, a multi-targeted antifolate that disrupts synthesis of both purines and pyrimidines, is approved for use in malignant pleural mesothelioma and non-small cell lung cancer. Pemetrexed is currently being evaluated for anti-tumor activity in a variety of solid and central nervous system tumors. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of pemetrexed in a non-human primate model that is highly predictive of human CSF penetration. METHODS: Pemetrexed, 20 mg/kg (400 mg/m2), was administered intravenously to four non-human primates. Serial blood samples were obtained from all animals and serial CSF samples were obtained from three animals. Plasma and CSF concentrations of pemetrexed were measured using LC/MS/MS and the resulting concentration versus time data were evaluated using model independent and dependent methods. RESULTS: Pemetrexed disappearance from plasma was best described by a two compartment model with a mean distribution half-life of 13.8 +/- 3.2 min and an elimination half-life of 70.0 +/- 16.0 min. The volume of distribution of and the clearance from the central compartment were 0.066 +/- 0.017 l/kg and 3.6 +/- 0.6 ml/min/kg, respectively. Peak CSF concentrations occurred 40-71 min after the start of the infusion with an average of 0.26 +/- 0.15 microM. CONCLUSION: The CSF penetration of pemetrexed was less than 2% (range 0.33-1.58%), suggesting that it should be used in conjunction with other CNS preventive strategies when used in the treatment of malignancies with a predilection for CNS or leptomeningeal metastases.

Animals↗
PubMed2002

Molecular, biochemical, and cellular pharmacology of pemetrexed.

Pemetrexed is a new-generation antifolate that in its higher polyglutamyl forms is a potent, direct inhibitor of thymidylate synthase and, to a lesser extent, glycinamide ribonucleotide transformylase. Activity of the drug may be partially preserved under conditions in which cells are highly resistant to other thymidylate synthase inhibitors, possibly because of premetrexed's secondary inhibitory effects on purine synthesis. Pemetrexed inhibition of dihydrofolate reductase is not of pharmacologic importance. Pemetrexed has high affinity for the reduced folate carrier and folate receptor and is among the most potent substrates for folylpolyglutamate synthetase. These properties result in rapid accumulation of the free drug in cells with the rapid formation of high levels of the active polyglutamyl congeners. Pemetrexed activity is modulated by natural folates within cells that compete for polyglutamation at the level of folylpolyglutamate synthetase. Cells resistant to methotrexate because of impaired transport via the reduced folate carrier may retain partial sensitivity to pemetrexed. This is due to concurrent diminished transport of physiologic reduced folates and contraction of the cellular folate pool, thereby relaxing the usual level of suppression of pemetrexed polyglutamation. The risk of pemetrexed toxicity is increased when cellular folates are suboptimal. This is best monitored by assessment of blood homocysteine levels, and can be diminished by the coadministration of folic acid.

Animals↗
PubMed2002

Phase II trial of pemetrexed disodium (ALIMTA, LY231514) in chemotherapy-naïve patients with advanced non-small-cell lung cancer.

BACKGROUND: To evaluate the efficacy and safety of pemetrexed therapy for chemotherapy-naïve patients with surgically incurable non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Eligible patients received pemetrexed 600 mg/m2 every 3 weeks. Restaging was performed after every two cycles of therapy and toxicity was assessed at each cycle of pemetrexed. In the absence of disease progression or undue toxicity, treatment was continued for a maximum of 12 cycles. RESULTS: Fifty-nine patients (median age 59 years; range 39-74 years) received a median of four cycles of pemetrexed. Nineteen patients (32%) had a ECOG performance status (PS) of two and 39 patients (66%) had stage IV disease. The most common histological sub-types were adenocarcinoma (20 patients, 34%) and large cell (18 patients, 31%). Sixteen patients (27%) had received prior radiotherapy. Nine patients achieved a partial response for an overall response rate of 15.8% (95% confidence interval CI 7% to 28%). The median duration of response was 4.9 months, and the median survival was 7.2 months. The principal toxicities were myelosuppression and rash. While grade 3 or 4 neutropenia was seen in 25 patients (42%), only two patients (3%) developed grade 3 infection. Eighteen patients (31%) developed grade 3 or 4 cutaneous toxicity, which improved with prophylactic oral dexamethasone administered for 3 days beginning the day before pemetrexed treatment. Asymptomatic elevations in hepatic biochemistry (especially alanine transaminase and aspartate transaminase) were seen in 47 patients (80%); however, these did not interfere with the dose or schedule of pemetrexed and returned to normal levels throughout the study. CONCLUSIONS: This is the largest study confirming the encouraging single-agent activity of pemetrexed in chemotherapy-naïve patients with NSCLC. In addition, this study demonstrates that a dose of 600 mg/m2 can be delivered safely; however, treatment should be restricted to patients with a PS of 0 or 1. The results of combination studies are awaited with interest.

Adult↗
PubMed2004

Synergistic cytotoxicity and pharmacogenetics of gemcitabine and pemetrexed combination in pancreatic cancer cell lines.

PURPOSE: Gemcitabine is an inhibitor of ribonucleotide reductase (RR) and DNA synthesis and is an effective agent in the treatment of pancreas cancer. The present study investigates whether the multitargeted antifolate pemetrexed would be synergistic with gemcitabine against MIA PaCa-2, PANC-1, and Capan-1 pancreatic cancer cell lines. EXPERIMENTAL DESIGN: Cells were treated with gemcitabine and pemetrexed, and the type of drug interaction was assessed using the combination index. Cytotoxicity of gemcitabine was examined with inhibitors of (a) deoxycytidine kinase (dCK), which activates gemcitabine by phosphorylation, and (b) 5'-nucleotidase (drug dephosphorylation) and cytidine deaminase (drug deamination), the main inactivating enzymes. The effects of gemcitabine and pemetrexed on cell cycle were analyzed by flow cytometry, and apoptosis was examined by fluorescence microscopy. Finally, quantitative, real-time PCR was used to study the pharmacogenetics of the drug combination. RESULTS: Synergistic cytotoxicity and enhancement of apoptosis was demonstrated, mostly with the sequence pemetrexed-->gemcitabine. Pemetrexed increased cells in S phase, the most sensitive to gemcitabine, and a positive correlation was found between the expression ratio of dCK:RR and gemcitabine sensitivity. Indeed, pemetrexed significantly enhanced dCK gene expression (+227.9, +86.0, and +135.5% in MIA PaCa-2, PANC-1, and Capan-1 cells, respectively), and the crucial role of this enzyme was confirmed by impairment of gemcitabine cytotoxicity after dCK saturation with 2'-deoxycytidine. CONCLUSIONS: These data demonstrate that the gemcitabine and pemetrexed combination displays schedule-dependent synergistic cytotoxic activity, favorably modulates cell cycle, induces apoptosis, and enhances dCK expression in pancreatic cancer cells.

Antimetabolites, Antineoplastic↗
PubMed2006

A phase II trial of pemetrexed in advanced breast cancer: clinical response and association with molecular target expression.

PURPOSE: This phase II trial of pemetrexed explored potential correlations between treatment outcome (antitumor activity) and molecular target expression. EXPERIMENTAL DESIGN: Chemonaïve patients with advanced breast cancer received up to three cycles of pemetrexed 500 mg/m2 (10-minute i.v. infusion) on day 1 of a 21-day cycle, with folic acid and vitamin B12 supplementation. Tumors were surgically removed after the last cycle of pemetrexed as clinically indicated. Biopsies were taken at baseline, 24 hours after infusion in cycle 1, and after cycle 3. RESULTS: Sixty-one women (median age, 46 years; range, 32-72 years) were treated and were evaluable for response. Objective response rate was 31%. Simple logistic regression suggested a potential relationship between mRNA expression of thymidylate synthase (TS) and pemetrexed response (P = 0.103). Based on threshold analysis, patients with "low" baseline TS (< or = 71) were more likely to respond to pemetrexed than patients with "high" baseline TS (>71). Expression of baseline dihydrofolate reductase and glycinamide ribonucleotide formyl transferase tended to be higher in responders but this association was not significant (P > 0.311). TS expression increased significantly between baseline and biopsy 2 (P = 0.004) and dropped to near baseline levels at biopsy 3. Conversely, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase decreased after pemetrexed chemotherapy. CONCLUSIONS: Our results suggest a potential association between "low" pretreatment TS expression levels and response to pemetrexed chemotherapy. Future trials examining expression levels of other genes important to the folate pathway and/or breast cancer may identify a more robust multigene profile that can better predict response to this novel antifolate.

Adult↗
PubMed2005

Pemetrexed therapy for malignant pleural mesothelioma.

OBJECTIVE: To review pemetrexed, a novel multi-targeted antifolate agent. DATA SOURCES: A literature search was conducted (1985-September 2004) using MEDLINE and CANCERLIT. Recent abstracts from the American Society of Clinical Oncology were also included, along with the manufacturer's information. Key words were pemetrexed, LY-231514, Alimta, multi-targeted antifolate, malignant pleural mesothelioma. STUDY SELECTION AND DATA EXTRACTION: Relevant information on pharmacology, pharmacokinetics, and safety and efficacy of pemetrexed from clinical trials was selected. DATA SYNTHESIS: Pemetrexed inhibits folate metabolism and purine/pyrimidine synthesis. Based on Phase I and II trials, pemetrexed has antitumor activity in solid tumors such as lung, colorectal, and cervical. A pivotal Phase III study in patients with malignant pleural mesothelioma (MPM) demonstrated survival superiority of pemetrexed-cisplatin regimen versus cisplatin. CONCLUSIONS: Pemetrexed is a promising new drug for the treatment of solid malignancies, most notably MPM.

Antimetabolites, Antineoplastic↗