The differential efficacy of pemetrexed according to NSCLC histology: a review of two Phase III studies.

BACKGROUND: Recent studies of pemetrexed have identified a predictive role for non-small cell lung cancer (NSCLC) histology. We further reviewed the differential efficacy of pemetrexed according to histology in two large, phase III NSCLC trials. METHODS: One study tested pemetrexed versus docetaxel in previously treated patients (n = 571) and the other tested cisplatin plus pemetrexed versus cisplatin plus gemcitabine in chemotherapy-naive patients (n = 1,725) with advanced NSCLC. Cox proportional hazard models were used to test for covariate-adjusted treatment-by-histology interactions (THIs) for overall survival (OS) and progression-free survival (PFS). For each histologic subgroup, the Kaplan-Meier method was used to estimate unadjusted within-arm medians, and Cox models were used to estimate covariate-adjusted between-arm hazard ratios (HRs). RESULTS: In both studies, treatment arms were well balanced for histology. THIs were statistically significant (p < .005) for both OS and PFS. Nonsquamous patients treated with pemetrexed-based therapy experienced longer survival than the comparators (HR, 0.78 and 0.84, respectively), whereas squamous patients had shorter survival (HR, 1.56 and 1.23, respectively). Whereas the efficacy of pemetrexed regimens differed according to histology, it did not differ for docetaxel or for cisplatin plus gemcitabine. Pemetrexed was well tolerated across histologic groups. CONCLUSIONS: The consistency of these results across studies confirms the predictive effect of histology for pemetrexed and the survival advantage for pemetrexed in patients with nonsquamous histology. These analyses suggest pemetrexed should not be recommended for the treatment of squamous cell carcinoma, but, because of efficacy and safety advantages, pemetrexed may be preferable to other agents for treatment of patients with nonsquamous NSCLC.

Pemetrexed plus cisplatin or pemetrexed plus carboplatin for chemonaïve patients with malignant pleural mesothelioma: results of the International Expanded Access Program.

INTRODUCTION: Previously published results from a randomized phase III study of pemetrexed plus cisplatin in patients with malignant pleural mesothelioma (MPM) demonstrated a significant survival benefit and higher response rate compared with cisplatin. Although pemetrexed was under review by regulatory agencies, an International Expanded Access Program (EAP) provided more than 3000 mesothelioma patients with access to single-agent pemetrexed or pemetrexed in combination with cisplatin or carboplatin in 13 countries. This manuscript reports the safety and efficacy data from the nonrandomized open-label study in chemonaïve patients receiving pemetrexed plus platinum under the EAP. METHODS: Patients with histologically confirmed MPM, not amenable to curative surgery, received pemetrexed 500 mg/m in combination with either cisplatin 75 mg/m or carboplatin AUC 5, once every 21 days with standard premedication. Efficacy data were recorded at the end of study participation. RESULTS: A total of 1704 chemonaïve patients received pemetrexed plus cisplatin (n = 843) or pemetrexed plus carboplatin (n = 861) and were evaluated for safety. The efficacy evaluable population consisted of 745 patients in the pemetrexed plus cisplatin group and 752 patients in the pemetrexed plus carboplatin group for whom physician-reported tumor response was available. The pemetrexed plus cisplatin group demonstrated a response rate of 26.3% compared with 21.7% for the pemetrexed plus carboplatin group, with similar 1-year survival rates (63.1% versus 64.0%) and median time to progressive disease (7 months versus 6.9 months). The most common grade 3/4 hematologic toxicity was neutropenia in 23.9% of the pemetrexed plus cisplatin group and 36.1% of the pemetrexed plus carboplatin group. CONCLUSION: This large EAP confirmed the activity of pemetrexed plus cisplatin and pemetrexed plus carboplatin in chemonaïve patients with MPM, demonstrating clinically similar time to progressive disease and 1-year survival rates.

Single-agent pemetrexed for chemonaïve and pretreated patients with malignant pleural mesothelioma: results of an International Expanded Access Program.

INTRODUCTION: Pemetrexed has established efficacy, and is the backbone for chemotherapy in patients with malignant pleural mesothelioma (MPM). An International Expanded Access Program provided >3000 mesothelioma patients with access to single-agent pemetrexed or pemetrexed plus platinum analogs (cisplatin or carboplatin) in 13 countries. In this article, we report the safety and efficacy data of MPM patients who were treated with single-agent pemetrexed (n = 812). METHODS: Patients with histologically confirmed MPM, not amenable to curative surgery, received pemetrexed (500 mg/m) once (day 1) every 21 days with standard premedication and vitamin supplementation. Investigator-determined response and survival data were recorded at the end of study participation. Myelosuppression data were also collected. RESULTS: All 812 MPM patients (319 chemonaïve; 493 pretreated) received single-agent pemetrexed (>or=1 dose) and were evaluated for safety. A total of 643 patients (247 chemonaïve, 396 pretreated) were evaluated for efficacy. Of the chemonaïve patients evaluated for efficacy (n = 247), the overall response rate was 10.5%, median time to progressive disease (TTPD) was 6.0 months, and median survival was 14.1 month. Of the pretreated patients evaluated for efficacy (n = 396), the overall response rate was 12.1%, median TTPD was 4.9 months, and the median survival was not estimable due to high censoring. Common terminology criteria grade 3/4 hematologic toxicity was mild in both groups, with neutropenia (<18%) as the main toxicity. CONCLUSIONS: In the present expanded access program, single-agent pemetrexed demonstrated promising activity in MPM in both chemonaïve and pretreated patients, with TTPD of 6.0 and 4.9 months, respectively, 1-year survival >or=54.7%, and mild hematologic toxicity.

Phase III trial of pemetrexed plus best supportive care compared with best supportive care in previously treated patients with advanced malignant pleural mesothelioma.

PURPOSE: This multicenter, phase III study compared overall survival (OS) of second-line pemetrexed plus best supportive care (BSC) versus BSC alone in patients with advanced malignant pleural mesothelioma (MPM). Secondary end points included response rate, progression-free survival (PFS), time to tumor progression (TTP), time to treatment failure (TTF), and toxicity. PATIENTS AND METHODS: Patients with relapsed MPM after first-line chemotherapy were randomly assigned to receive pemetrexed 500 mg/m(2) plus BSC (P+BSC) every 21 days or BSC alone. RESULTS: The study enrolled 243 patients (123 on P+BSC arm and 120 on BSC arm). Median OS time was not significantly different between the arms (8.4 months for P+BSC and 9.7 months for BSC; P = .74). Cox regression modeling suggested a trending survival benefit for patients who responded to first-line therapy. Time-to-event measures significantly favored P+BSC (median PFS, TTP, and TTF). Partial response was achieved in 18.7% and 1.7% of patients in P+BSC and BSC arms, respectively (P < .0001), and a disease control rate (partial response plus stable disease) was achieved in 59.3% and 19.2% of patients in P+BSC and BSC arms, respectively (P < .0001). Use of postdiscontinuation chemotherapy was significantly greater among BSC patients compared with P+BSC patients (51.7% v 28.5%, respectively; P = .0002), with more BSC patients receiving pemetrexed (18.3% v 3.3%, respectively; P = .0001). Postdiscontinuation therapy was initiated earlier for BSC than P+BSC patients (median time to initiation, 4.3 v 15.7 months, respectively; log-rank P < .0001). Chemotherapy was well tolerated, with expected modest (4% to 7%) grade 3 and 4 hematologic toxicities. CONCLUSION: Second-line pemetrexed elicited significant tumor response and delayed disease progression compared with BSC alone in patients with advanced MPM. Improvement in OS was not seen in this study, possibly because of the significant imbalance in postdiscontinuation chemotherapy between the arms.

Correlations of mRNA expression and in vitro chemosensitivity to enzastaurin in freshly explanted human tumor cells.

PURPOSE: Enzastaurin (LY317615) is a novel serine/threonine kinase inhibitor, targeting Protein Kinase C-beta (PKC-beta), and PI3K/AKT pathways to inhibit angiogenesis and tumor cell proliferation. The aims of this study were to determine whether Enzastaurin has direct antitumor activity against freshly explanted tumor cells and to correlate mRNA expression of genes related to the proposed mechanism of action of enzastaurin with in vitro chemosensitivity. EXPERIMENTAL DESIGN: Freshly biopsied tumor cells were studied using soft-agar cell cloning experiments (SACCE) to determine the in vitro chemosensitivity to enzastaurin. An aliquot of the same tumor specimens was shock-frozen and total RNA was isolated for standardized multiplex rt-PCR experiments for gene expression of PKC-beta1, PKC-beta2, IL-8, IL-8RA, IL-8RB, Glycogen Synthase Kinase 3 beta (GSK-3beta) and TGF-beta1. Correlations, threshold optimization, sensitivity, specificity, and efficiency were analyzed using the appropriate statistical methodologies. RESULTS: Seventy-two tumor samples were collected and 63 were fully evaluable. Low levels of mRNA expression of GSK-3beta and high levels of mRNA expression of IL-8 were highly significantly correlated with chemosensitivity to enzastaurin. Optimization analyses demonstrated threshold values of 4,000 copies for IL-8 and three copies for GSK-3beta relative to 10(4) copies of beta-actin. However, no correlation between mRNA expression of PKC-beta1, PKC-beta2, IL-8RA, IL-8RB and chemosensitivity to enzastaurin was observed. Expression of TGF-beta1 mRNA was not detectable in the specimens investigated. CONCLUSIONS: mRNA expression levels of IL-8 and GSK-3beta correlate with antitumor activity of enzastaurin. These results form a rational basis for clinical trials to evaluate the expression of these genes as potential predictors for treatment outcome after enzastaurin chemotherapy.

Antifolate pseudo-resistance due to elevated levels of thymidine and hypoxanthine in a commercial serum preparation.

BACKGROUND: Batch variability of sera used for cell culture is of considerable experimental concern. A novel fetal calf serum product, FCS Gold, was claimed to be the first defined fetal calf serum free of batch variation. MATERIALS AND METHODS: The efficacy of methotrexate (MTX) and LY231514 (multitargeted antifolate, MTA) in CCRF-CEM cells and KB cells was compared using media supplemented with FCS Gold or conventional fetal bovine serum. RESULTS: IC50 values from tests using conventional serum corresponded to published data. FCS Gold fully protected the cells from antifolate drug cytotoxicity. Dialysis of FCS Gold restored responsiveness to antifolate drugs. Elevated levels of hypoxanthine and thymidine were present in FCS Gold. They were approximately 10-fold greater than the concentrations required to overcome growth arrest mediated by 2 microM MTX. CONCLUSION: FCS Gold or identical products, e.g. FBS Gold, should not be used in studies on antifolate drug action.

A randomized phase II trial of pemetrexed plus irinotecan (ALIRI) versus leucovorin-modulated 5-FU plus irinotecan (FOLFIRI) in first-line treatment of locally advanced or metastatic colorectal cancer.

BACKGROUND: This multicenter, randomized trial compared overall response rate between pemetrexed plus irinotecan (ALIRI) and leucovorin-modulated 5-fluorouracil plus irinotecan (FOLFIRI) in patients with advanced colorectal cancer. Secondary objectives included overall and progression-free survival, duration of response, toxicities, and biomarkers. PATIENTS AND METHODS: ALIRI patients received pemetrexed 500 mg/m(2) and irinotecan 350 mg/m(2) with vitamin supplementation on day 1 of each 21-day cycle. FOLFIRI patients received irinotecan 180 mg/m(2) on days 1, 15, 29; on days 1, 2, 15, 16, 29, 30, patients received leucovorin 200 mg/m(2), bolus 5-fluorouracil 400 mg/m(2), and 5-fluorouracil 600 mg/m(2) as 22-hour infusion. RESULTS: Of 132 patients randomly assigned, 130 patients (64 = ALIRI, 66 = FOLFIRI) received > or =1 dose of treatment. Response rates (ALIRI = 20.0%, FOLFIRI = 33.3%) were not significantly different between arms (p = 0.095). Progression-free survival was 5.7 months for ALIRI and 7.7 months for FOLFIRI (p < 0.001). Neutropenia, fatigue, diarrhea, nausea, and vomiting were the major toxicities. There were 5 drug-related deaths (ALIRI = 4, FOLFIRI = 1). Biomarker analysis failed to reveal that any of the 18 preselected genes were clearly associated with tumor response. CONCLUSIONS: Neither efficacy nor safety improved on the ALIRI arm compared to the FOLFIRI arm. Progression-free survival on FOLFIRI was significantly longer compared to ALIRI. Potential biomarkers capable of predicting response to either regimen in advanced or metastatic colorectal carcinoma need further characterization.

Assessment of the value of confirming responses in clinical trials in oncology.

The requirement for a second assessment to confirm initial tumour response is required by all response guidelines. Its rationale, however, is not clear. We have conducted this study to compare validity of response rate assessment determined with and without secondary confirmation. Using specified criteria, nine trials of one single cytotoxic drug including 416 patients were selected from a pharmaceutical database. Objective response rates were determined by a single determination and by two separate determinations. 81 responses (19.5%, [15.8-23.6%]) were scored by the confirmation method and 97 responses (23.3% [19.3-27.7%]) by the no-confirmation method. The Kappa (kappa) coefficient of 0.89 indicates good agreement between both methods. This is the first study that systematically compares response rates calculated with and without performing response confirmation. Results show good agreement between both methods. We suggest that assessing response without confirmation may be the preferred method. These results should be confirmed by additional studies in a variety of cancer settings.

Pemetrexed combined with oxaliplatin or carboplatin as first-line treatment in advanced non-small cell lung cancer: a multicenter, randomized, phase II trial.

PURPOSE: To determine efficacy and toxicity of two pemetrexed-based regimens in chemonaive patients with locally advanced or metastatic non-small cell lung cancer. EXPERIMENTAL DESIGN: Patients were randomly assigned to receive pemetrexed 500 mg/m(2) plus oxaliplatin 120 mg/m(2) (PemOx) or pemetrexed plus carboplatin AUC6 (PemCb). All drugs were given on day 1 of a 21-day cycle for up to six cycles. Folic acid and vitamin B(12) were given to all patients to minimize pemetrexed-related toxicities. RESULTS: Forty-one patients received PemOx and 39 received PemCb. Objective tumor response rates were 26.8% for PemOx patients (95% confidence interval, 14.2-42.9) and 31.6% for PemCb patients (95% confidence interval, 17.5-48.7). Median time to progression was 5.5 and 5.7 months, respectively, for PemOx and PemCb. Median overall survival times were 10.5 months for both treatment groups (range, <1 to >20 months). The 1-year survival rate was 49.9% for PemOx patients and 43.9% for PemCb patients. Common toxicity criteria grade 3 or 4 hematologic toxicities among PemOx patients were grade 3 or 4 neutropenia (7.3%), grade 3 thrombocytopenia (2.4%), and grade 3 anemia (2.4%). PemCb patients experienced grade 3 or 4 neutropenia (25.6%), grade 3 or 4 thrombocytopenia (17.9%), and grade 3 anemia (7.7%). Grade 3 vomiting occurred in three PemOx patients and grade 3 fatigue occurred in three PemCb patients. One grade 3 neurosensory toxicity occurred in the PemOx group. Three patients (PemOx 1 and PemCb 2) experienced febrile neutropenia. CONCLUSIONS: Efficacy measures for both regimens seem similar to the most effective chemotherapies for advanced non-small cell lung cancer (platinum combinations) with less hematologic and nonhematologic toxicity. Comparing either of these two regimens to platinum-based therapies in a large randomized trial is warranted.

Phase II study of pemetrexed with and without folic acid and vitamin B12 as front-line therapy in malignant pleural mesothelioma.

PURPOSE: This phase II clinical study evaluated the efficacy of pemetrexed for the treatment of malignant pleural mesothelioma (MPM). PATIENTS AND METHODS: Patients with a histologically proven diagnosis of MPM, chemotherapy-naive measurable lesions, and adequate organ function received pemetrexed (500 mg/m2) intravenously over 10 minutes every 3 weeks. After a protocol change, most patients also received folic acid and vitamin B12 supplementation to improve safety. RESULTS: A total of 64 patients were enrolled. Nine (14.1%) of the 64 patients had a partial response. The Kaplan-Meier estimate for median overall survival was 10.7 months. Forty-three patients received vitamin supplementation for all courses of therapy, and 21 patients did not. Seven of the nine responders were vitamin supplemented. The median overall survival was 13.0 months for supplemented patients and 8.0 months for nonsupplemented patients. Vitamin-supplemented patients completed more cycles of therapy than nonsupplemented patients (median, six v two cycles, respectively). Grade 3/4 neutropenia (23.4%) and grade 3/4 leukopenia (18.8%) were the most common laboratory toxicities. Fatigue and febrile neutropenia were the most commonly reported nonlaboratory events (grade 3, 6.3%; grade 4, 0.0% each). The incidence of these toxicities was generally lower in the supplemented patients. CONCLUSION: Single-agent pemetrexed for MPM resulted in a moderate response rate (14.1%) and median overall survival of 10.7 months. Patients supplemented with folic acid and vitamin B12 tolerated treatment better (less toxicity and more cycles of treatment) and had a 5-month greater median overall survival than nonsupplemented patients. These results indicate that patients with MPM could benefit from single-agent pemetrexed treatment combined with vitamin supplementation.

Preclinical evaluation of gemcitabine/paclitaxel-interactions in human bladder cancer lines.

BACKGROUND: Gemcitabine and paclitaxel are currently co-administered in clinical studies for bladder cancer as this drug combination may offer better tumor responses. However, the drugs may antagonize the cytotoxic capacity of each other due to cell cycle perturbations. In this study, we evaluated different application schedules to determine the efficacy of the combination and its potential interactions. MATERIALS AND METHODS: Bladder cancer cell lines were exposed to either gemcitabine or paclitaxel, in concentrations ranging from 1-1000 nM. The inhibition concentrations (IC) 20, 50 and 70 were assessed by MTT assay after 24, 48 and 72 hours. Then, the cytotoxic activity and apoptosis induction abilities of the combined agents using the IC20 concentration were analyzed by MTT and Annexin-V/PI staining, respectively. The effects on the cell cycle were assessed by flow cytometry of bromodeoxyuridine (BrdU) and propidium iodide (PI). RESULTS: Gemcitabine and paclitaxel dose-dependently inhibited cell proliferation. Simultaneous application of gemcitabine/paclitaxel yielded superior cytotoxicity rates after 48 and 72 hours. Sequential treatment of cells showed similar results when gemcitabine was given 24 hours before paclitaxel. However, when paclitaxel was given before gemcitabine, the cell kill was less. Gemcitabine as well as paclitaxel have potent apoptosis inducing abilities. Cell cycle evaluation demonstrated a shift towards the S-phase after gemcitabine and a progressive G2/M block after paclitaxel treatment. CONCLUSION: The combination of gemcitabine and paclitaxel in vitro yields superior cytotoxic efficacy, if given simultaneously or with gemcitabine first. While in vitro cell models may not necessarily predict clinical outcome, they do provide a basis for rational scheduling of drugs in clinical trials.

Interaction of pemetrexed disodium (ALIMTA, multitargeted antifolate) and irradiation in vitro.

PURPOSE: Pemetrexed disodium (Alimta, multitargeted antifolate, LY231514; Eli Lilly and Co., Indianapolis, Indiana) ("pemetrexed") is a new folate antimetabolite with significant antitumor activity. Different from classic antifolates, pemetrexed inhibits several key enzymes of thymidylate and purine synthesis, but a radiosensitizing potential may also be presumed. Therefore, the interaction of pemetrexed and ionizing radiation was studied for in vitro clonogenic survival of different human tumor cell lines. METHODS AND MATERIALS: Human colon (Widr), breast (MCF-7), cervix (Hela), and lung (LXI) carcinoma cells from log-phase cultures were exposed to pemetrexed (2 h) in combination with different radiation doses given 1 h before pemetrexed washout (all cell lines) or at different points of time before or after pemetrexed addition (Widr). Survival curves were analyzed according to the linear-quadratic (LQ) model, and mean inactivation doses (MID) and radiation enhancement ratios were calculated from the survival curve parameters. Cell-cycle progression of serum-stimulated and pemetrexed- or mock-treated Widr cells was monitored by flow cytometry. RESULTS: Radiosensitization was found for all cell lines at moderately toxic pemetrexed exposures (0.05-0.3 microg/ml [106-636 nM]), but this was cell-type dependent and was most pronounced at roughly isotoxic concentrations, for the least pemetrexed-sensitive Widr cells. Enhancement ratios ranged from about 1.2 (MCF-7 and Hela) to 1.8 (Widr), with a tendency to increase with pemetrexed concentration. Little, if any, change of radiosensitization was observed (Widr) when the time of irradiation was varied from 4 h before to 10 h after the beginning of pemetrexed treatment. Cell-cycle progression of serum-stimulated Widr cells was only marginally affected by pemetrexed. CONCLUSIONS: Pemetrexed enhances radiation-induced cell inactivation at moderately toxic exposures and over many hours after drug removal. This effect is not due to disturbed cell-cycle progression, but likely involves an interaction of pemetrexed with long-lived (>4 h) cellular radiation damage and needs to be considered when introducing a combined clinical application.