Initial phase I evaluation of the novel thymidylate synthase inhibitor, LY231514, using the modified continual reassessment method for dose escalation

Renal function-based versus standard dosing of pemetrexed: a randomized controlled trial

PURPOSE

Pemetrexed is a chemotherapeutic drug in the treatment of non-small cell lung cancer and mesothelioma. Optimized dosing of pemetrexed based on renal function instead of body surface area (BSA) is hypothesized to reduce pharmacokinetic variability in systemic exposure and could therefore improve treatment outcomes. The aim of this study is to compare optimized dosing to standard BSA-based dosing.

METHODS

A multicenter randomized (1:1) controlled trial was performed to assess superiority of optimized dosing versus BSA-based dosing in patients who were eligible for pemetrexed-based chemotherapy. The individual exposure to pemetrexed in terms of area under the concentration-time curve (AUC) was determined. The fraction of patients attaining to a predefined typical target AUC (164 mg × h/L ± 25%) was calculated.

RESULTS

A total of 81 patients were included. Target attainment was not statistically significant different between both arms (89% vs. 84% (p = 0.505)). The AUC of pemetrexed was similar between the optimized dosing arm (n = 37) and the standard of care arm (n = 44) (155 mg × h/L vs 160 mg × h/L (p = 0.436).

CONCLUSION

We could not show superiority of optimized dosing of pemetrexed in patients with an adequate renal function does not show added value on the attainment of a pharmacokinetic endpoint, safety, nor QoL compared to standard of care dosing.

CLINICAL TRIAL NUMBER

Clinicaltrials.gov identifier: NCT03655821.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

Mechanisms, Management and Prevention of Pemetrexed-Related Toxicity

Pemetrexed is a cytostatic antifolate drug and a cornerstone in the treatment of lung cancer. Although generally well tolerated, a substantial part of the patient population experiences dose-limiting or even treatment-limiting toxicities. These include mucositis, skin problems, fatigue, renal toxicity, and neutropenia. Several studies confirmed that pemetrexed pharmacokinetics can serve as a prognostic factor for the development of toxicity, especially for neutropenia. Preventing and managing toxicity of pemetrexed can help to ensure durable treatment. Several evidence-based strategies are already implemented in clinical care. With the introduction of standard vitamin supplementation and dexamethasone, the incidence of hematological toxicity and skin reactions substantially decreased. In the case of high risk for toxicity, granulocyte colony-stimulating factor can be used to prevent severe hematological toxicity. Moreover, high-dose folinic acid can resolve severe pemetrexed-induced toxicity. There are several experimental options to prevent or manage pemetrexed-related toxicity, such as the use of standard folinic acid, hemodialysis, antidotes such as thymidine, hypoxanthine, and glucarpidase, and the use of therapeutic drug monitoring. These strategies still need clinical evaluation before implementation, but could enable treatment with pemetrexed for patients who are at risk for toxicity, such as in renal impairment.

Toxicity of pemetrexed during renal impairment explained-Implications for safe treatment

Pemetrexed is an important component of first line treatment in patients with non-squamous non-small cell lung cancer. However, a limitation is the contraindication in patients with renal impairment due to hematological toxicity. Currently, it is unknown how to safely dose pemetrexed in these patients. The aim of our study was to elucidate the relationship between pemetrexed exposure and toxicity to support the development of a safe dosing regimen in patients with renal impairment. A population pharmacokinetic/pharmacodynamic analysis was performed based on phase II study results in three patients with renal dysfunction, supplemented with data from 106 patients in early clinical studies. Findings were externally validated with data of different pemetrexed dosing regimens. Alternative dosing regimens were evaluated using the developed model. We found that pemetrexed toxicity was driven by the time above a toxicity threshold concentration. The threshold for vitamin-supplemented patients was 0.110 mg/mL (95% CI: 0.092-0.146 mg/mL). It was observed that in patients with renal impairment (estimated glomerular filtration rate [eGFR]: <45 mL/min) the approved dose of 500 mg/m² would yield a high probability of severe neutropenia in the range of 51.0% to 92.6%. A pemetrexed dose of 20 mg for patients (eGFR: 20 mL/min) is shown to be neutropenic-equivalent to the approved dose in patients with adequate renal function (eGFR: 90 mL/min), but would result in an approximately 13-fold lower area under the concentration-time curve. The pemetrexed exposure-toxicity relationship is explained by a toxicity threshold and substantially different from previously thought. Without prophylaxis for toxicity, it is unlikely that a therapeutic dose can be safely administered to patients with renal impairment.

Moving Beyond 3+3: The Future of Clinical Trial Design

Misgivings have been raised about the operating characteristics of the canonical 3+3 dose-escalation phase I clinical trial design. Yet, the traditional 3+3 design is still the most commonly used. Although it has been implied that adhering to this design is due to a stubborn reluctance to adopt change despite other designs performing better in hypothetical computer-generated simulation models, the continued adherence to 3+3 dose-escalation phase I strategies is more likely because these designs perform the best in the real world, pinpointing the correct dose and important side effects with an acceptable degree of precision. Beyond statistical simulations, there are little data to refute the supposed shortcomings ascribed to the 3+3 method. Even so, to address the unique nuances of gene- and immune-targeted compounds, a variety of inventive phase 1 trial designs have been suggested. Strategies for developing these therapies have launched first-in-human studies devised to acquire a breadth of patient data that far exceed the size of a typical phase I design and blur the distinction between dose selection and efficacy evaluation. Recent phase I trials of promising cancer therapies assessed objective tumor response and durability at various doses and schedules as well as incorporated multiple expansion cohorts spanning a variety of histology or biomarker-defined tumor subtypes, sometimes resulting in U.S. Food and Drug Administration approval after phase I. This article reviews recent innovations in phase I design from the perspective of multiple stakeholders and provides recommendations for future trials.

Pemetrexed exposure predicts toxicity in advanced non-small-cell lung cancer: A prospective cohort study

BACKGROUND

We explored whether total exposure to pemetrexed predicts effectiveness and toxicity in advanced non-small-cell lung cancer (NSCLC). Furthermore, we investigated alternative dosing schedules.

METHODS

In this prospective cohort study, patients with advanced NSCLC receiving first- or second-line pemetrexed(/platinum) were enrolled. Plasma sampling was performed weekly (cyclePK) and within 24 h (24hPK) after pemetrexed administration. With population pharmacokinetic/pharmacodynamic modelling, total exposure to pemetrexed during cycle 1 (area under the curve during chemotherapy cycle 1 [AUC₁]) was estimated and related to progression-free survival (PFS)/overall survival (OS). We compared mean AUC₁ (mg·h/L) in patients with and without severe chemotherapy-related adverse events (AEs) during total treatment. Second, different dosing schedules were simulated to minimise the estimated variability (coefficient of variation [CV]) of AUC.

RESULTS

For 106 of 165 patients, concentrations of pemetrexed were quantified (24hPK, n = 15; cyclePK, n = 106). After adjusting for prognostic factors, sex, disease stage and World Health Organisation performance score, AUC₁ did not predict PFS/OS in treatment-naive patients (n = 95) (OS, hazard ratio [HR] = 1.05, 95% confidence interval [CI]: 1.00-1.11; PFS, HR = 1.03, 95% CI: 0.98-1.08). Patients with severe chemotherapy-related AEs (n = 55) had significantly higher AUC₁ values than patients without them (n = 51) (226 ± 53 vs 190 ± 31, p < 0.001). Compared with body surface area-based dosing (CV: 22.5%), simulation of estimated glomerular filtration rate (eGFR)-based dosing (CV 18.5%) and fixed dose of 900 mg with 25% dose reduction, if the eGFR<60 mL/min (CV: 19.1%), resulted in less interindividual variability of AUC.

CONCLUSIONS

Higher exposure to pemetrexed does not increase PFS/OS but is significantly associated with increased occurrence of severe toxicity. Our findings suggest that fixed dosing reduces interpatient pharmacokinetic variability and thereby might prevent toxicity, while preserving effectiveness.

Deciphering Clinicoradiologic Phenotype for Thymidylate Synthase Expression Status in Patients with Advanced Lung Adenocarcinoma Using a Radiomics Approach

We aimed to identify predictive clinicoradiologic characteristics of thymidylate synthase (TS) expression status in advanced non-squamous non-small cell lung cancer patients. We reviewed clinicoradiologic features of 169 patients stratified into TS-negative (n = 84) and TS-positive (n = 85) groups, including quantitative CT radiomic features of both primary lung and metastatic lesions from initial CT and PET. Clinical factors including age and smoking history were significantly associated with TS as well as radiomic features. The predictive performance for dichotomizing TS expression status was slightly higher when imaging features of primary lung lesions were added compared to the model based solely on the clinical features, but without statistical significance (10-fold cross-validated AUC = 0.619 and 0.581, respectively; P = 0.425). The predictive performance of clinicoradiologic parameters slightly increased with primary lung lesions only compared to the inclusion of metastatic lesions, but without statistical significance (10-fold cross-validated AUC = 0.619 and 0.554, respectively; P = 0.203). Overall survival was prolonged in the TS-negative group compared to the TS-positive group (P = 0.001). TS-negativity is a potential prognostic biomarker, and our study presents that although CT radiomic features have potential for predicting TS expression status, clinical significance is uncertain. The addition of radiomic features to clinical factors did not show significant improvement in predicting TS-negativity.

Single-dose dexamethasone for the prevention of pemetrexed associated cutaneous adverse reactions

Pemetrexed (Alimta®) is a novel anti-folate antimetabolite agent that is used in combination with cisplatin for the treatment of patients with unresectable malignant pleural mesothelioma and as a single agent or in combination with cisplatin for patients with locally advanced or metastatic non-small-cell-lung-cancer. Cutaneous adverse reactions are common side effects of pemetrexed for which the manufacturer recommends 3-day premedication with dexamethasone 4 mg by mouth twice daily—(the day before, the day of, and the day after treatment). Patients’ adherence to this premedication regimen is of concern. We report 14 cases of metastatic non-small-cell-lung-cancer patients who were premedicated with a single dose of dexamethasone 20 mg prior to pemetrexed or pemetrexed-based chemotherapy. None of these patients reported a grade 3 or above skin reactions over the course of their treatments. These findings suggest that a single dose of dexamethasone 20 mg may be an alternative premedication regimen in patients with metastatic non small cell lung cancer receiving pemetrexed or pemetrexed-based chemotherapy.

Associations between TS, TTF-1, FR-α, FPGS, and overall survival in patients with advanced non-small-cell lung cancer receiving pemetrexed plus carboplatin or gemcitabine plus carboplatin as first-line chemotherapy

INTRODUCTION

Pemetrexed is effective in the treatment of non-small-cell lung cancer, mainly in nonsquamous cell carcinomas. Inhibition of thymidylate synthase (TS) is considered the key mechanism of action. Folate receptor-α facilitates uptake of pemetrexed. Polyglutamation by folylpolyglutamate synthetase enhances activity and prolongs cellular retention of pemetrexed. Thyroid transcription factor-1 (TTF-1) is mainly positive in nonsquamous cell carcinoma and has been proposed as a marker for sensitivity to pemetrexed. The aim was to investigate associations between these biomarkers and survival in patients who participated in a phase III trial comparing pemetrexed plus carboplatin with gemcitabine plus carboplatin as first-line chemotherapy in advanced non-small-cell lung cancer (n = 436). In this study, there was no difference in overall survival between the two regimens.

METHODS

Formalin-fixed, paraffin-embedded biopsies were collected. Percentages of tumor cells positive and highly positive for the biomarkers were assessed using immunohistochemistry (IHC) and an IHC score was calculated (range, 0-200).

RESULTS

Two hundred thirty-six biopsies were analyzed (pemetrexed plus carboplatin: n = 114, gemcitabine plus carboplatin: n = 122). There was a significant difference in overall survival between those with TTF-1-positive and -negative tumors (10.4 versus 6.0 months; p < 0.001) and those with a low and a high TS IHC score (9.7 versus 6.2 months; p < 0.001). Folate receptor-α and folylpolyglutamate synthetase were not significant prognostic factors. In multivariate analyses adjusting for established prognostic characteristics, TS (p = 0.002) and TTF-1 (p = 0.003) remained significant. There were no differences in survival between the treatment arms depending on biomarker scores.

CONCLUSIONS

TTF-1 positivity and low TS level were associated with prolonged survival. The associations between the biomarkers and overall survival were similar for both chemotherapy regimens.

The place of pemetrexed in the management of non-small-cell lung cancer patients

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer death worldwide. Chemotherapy is included in the management of the majority of NSCLC patients either in addition to a local treatment (surgery/radiotherapy) or alone. In this setting, pemetrexed has become one of the most important partners of current chemotherapy regimens for nonsquamous NSCLC patients. Indeed, pemetrexed demonstrated a comparable efficacy to other previously available drugs in NSCLC, with however a better safety profile and an easier schedule of administration. In addition, pemetrexed demonstrated a greater efficacy in nonsquamous NSCLC that lead to an exploration of the underlying potential biological background. It is now suggested that the tumor thymidylate synthase level may act as a predictor of pemetrexed efficacy, therefore potentially providing clinicians in the future with a predictor of efficacy, which it is usually lacking with standard chemotherapies.

Electrochemical preparation of sodium dodecylsulfate doped over-oxidized polypyrrole/multi-walled carbon nanotube composite on glassy carbon electrode and its application on sensitive and selective determination of anticancer drug: pemetrexed

Electrochemical oxidation of pemetrexed (PMX) was studied on bare, carboxylic acid functionalized multi-walled carbon nanotubes and over-oxidized polypyrrole modified (oo-PPy/MWCNTs-COOH/GCE) glassy carbon electrodes by cyclic and adsorptive stripping differential pulse voltammetric techniques. The oo-PPy/MWCNTs-COOH/GCE is very sensitive to the oxidation of PMX. The results proved that the over-oxidation of the PPy film gave a negative charge density on porous layer that improved the adsorption for PMX. The effects of pH, concentrations of MWCNTs and monomer, the number of cycles for the electropolymerization and the scan rate for sensor preparation were optimized. The MWCNTs-COOH and oo-PPy based sensor showed an excellent recognition capacity toward PMX. The linear responses have been obtained in the range from 8.00 × 10(-7)M to 1.00 × 10(-4)M with 2.04 × 10(-7)M detection limit for the bare GCE and from 1.00 × 10(-8)M to 1.00 × 10(-7)M with 3.28 × 10(-9)M detection limit for the modified GCE. The oxidation of PMX was controlled by the adsorption process on both types of electrode surfaces. The proposed methods were compared with the literature on UV spectrophotometric assay, which was carried out at an absorption maximum of 225 nm. The proposed method and the designed sensors have been successfully applied for the determination of PMX in pharmaceuticals.

Personalizing colon cancer therapeutics: targeting old and new mechanisms of action

The use of pharmaceuticals for colon cancer treatment has been increasingly personalized, in part due to the development of new molecular tools. In this review, we discuss the old and new colon cancer chemotherapeutics, and the parameters that have been shown to be predictive of efficacy and safety of these chemotherapeutics. In addition, we discuss how alternate pharmaceuticals have been developed in light of a potential lack of response or resistance to a particular chemotherapeutic.

A new ultrafast and high-throughput mass spectrometric approach for the therapeutic drug monitoring of the multi-targeted anti-folate pemetrexed in plasma from lung cancer patients

An analytical assay has been developed and validated for ultrafast and high-throughput mass spectrometric determination of pemetrexed concentrations in plasma using matrix assisted laser desorption/ionization–triple quadrupole–tandem mass spectrometry. Patient plasma samples spiked with the internal standard methotrexate were measured by multiple reaction monitoring. The detection limit was 0.4 fmol/μL, lower limit of quantification was 0.9 fmol/μL, and upper limit of quantification was 60 fmol/μL, respectively. Overall observed pemetrexed concentrations in patient samples ranged between 8.7 (1.4) and 142.7 (20.3) pmol/μL (SD). The newly developed mass spectrometric assay is applicable for (routine) therapeutic drug monitoring of pemetrexed concentrations in plasma from non-small cell lung cancer patients.

Intrapleural administration of lipoplatin in an animal model

BACKGROUND

Lipoplatin is a new liposomal cisplatin already tested in solid tumors with encouraging results. Little is known about the activity of lipoplatin administered intrapleurally (IP).

AIM

The aim of this study was to assess in an animal model the pharmacokinetics, and potentially induced histopathological lesions of lung and kidney after IP vs. IV injection of lipoplatin.

METHODS

15 male Wistar rats were assigned to an IV group at dose 10mg/kg of lipoplatin (group 1) and to IP groups at 10 (group 2) or 20mg/kg (group 3) equal to 60 and 120 mg/m(2) in humans respectively. After lipoplatin administration, serial plasma samples were analyzed by atomic absorption spectrometry for the maximum plasma concentration (C(max)), the area under the plasma concentration-time curve (AUC), and the total body clearance (CL). Pleura, lungs and kidneys of the rats were histologically examined for possible lesions.

RESULTS

The C(max) was significantly higher in groups 1 vs. 2 (p = 0.02) and vs. 3 (p = 0.01). The AUC of groups 3 vs. 1 was significantly higher (p = 0.028) but the AUC of groups 2 vs. 1 was significantly lower (p = 0.02). CL in IP rats did not differ considerably compared to the IV. Inflammatory changes were noted in the pleura of IP rats and mild kidneys lesions in IV group.

CONCLUSION

Compared to the IV route, IP20 administration of lipoplatin yielded higher AUC, equal CL, but a significantly lower C(max). As C(max) is a determinant of lipoplatin toxicity, IP administration might offer a more effective therapeutic index while improving tolerability. We noted fibrotic changes in the pleura of IP rats, and mild kidneys changes in IV rats, as expected.

Pemetrexed in advanced non-small-cell lung cancer

IMPORTANCE OF THE FIELD

Current therapeutic options for advanced non-small-cell lung cancer (NSCLC) yield relatively modest improvements in survival leading to an ongoing search for new active treatment agents. In the past decade, pemetrexed has had an increasingly established role in the treatment of advanced NSCLC in both first- and second-line settings.

AREAS COVERED IN THIS REVIEW

Currently available published data on mechanism of action, pharmacokinetics, safety and efficacy of pemetrexed in the treatment of advanced NSCLC are described. Peer-reviewed publications on the development of pemetrexed and its clinical use in NSCLC were reviewed (1995 - 2009).

WHAT THE READER WILL GAIN

Pemetrexed is a multitargeted antifolate cytotoxic agent. Key Phase II and Phase III trials are described that have shown pemetrexed's efficacy in both the first- and second-line treatment of advanced NSCLC. The efficacy of pemetrexed seems to vary between squamous and nonsquamous histologies. Possible reasons for this are explored. Additionally, the potential role of pemetrexed in maintenance therapy is discussed.

TAKE HOME MESSAGE

Pemetrexed is an effective treatment for advanced NSCLC, with an overall favorable toxicity profile. There is growing evidence that, in patients treated with pemetrexed, nonsquamous tumors have improved outcomes compared to squamous cell tumors. Pemetrexed may also have a role in maintenance therapy for NSCLC.

Emerging role of pemetrexed in ovarian cancer

The current treatment of choice of epithelial ovarian cancer involves aggressive tumor cytoreductive surgery followed by platinum- and taxane-based chemotherapy; however, despite the encouraging activity of these agents, most ovarian carcinomas relapse and many patients die from drug-resistant disease. After the failure of platinum- and taxane-based schedules, several cytotoxic agents have demonstrated activity in advanced ovarian cancer but none were able to induce significant and durable responses. Among the new cytotoxic agents, pemetrexed plays an emerging role in different tumors, demonstrating competitive activity and a promising safety profile. In ovarian cancer, pemetrexed has been investigated, with encouraging results, as a single agent and in association with platinum compounds; moreover, the drug has shown interesting activity both in platinum-sensitive and platinum-resistant ovarian cancer. According to these clinical results it appears reasonable to explore the combination of pemetrexed with other cytotoxic agents and also with targeted therapies in relapsed ovarian cancer patients.

Intrapleural administration of pemetrexed: a pharmacokinetic study in an animal model

BACKGROUND

Pemetrexed is a key drug for the treatment of malignant pleural mesothelioma. The intrapleural administration of pemetrexed might increase its efficacy and decrease its toxicity in comparison with intravenous administration. The aim of this study was to assess in an animal model the pharmacokinetics of pemetrexed administered intrapleurally compared with intravenously.

METHODS

Thirty Wistar rats were randomly assigned to four groups defined by route (intravenous or intrapleural) and dose (10 or 100 mg/kg) of pemetrexed. After pemetrexed administration, serial plasma pemetrexed concentrations were analyzed by high performance liquid chromatography to determine the maximum plasma concentration (C(max)), the area under the plasma concentration-time curve (AUC), and the total body clearance (CL).

RESULTS

The C(max) was significantly lower after intrapleural versus intravenous administration of 10 mg/kg pemetrexed (14.36 microg/ml versus 29.83 microg/ml; p = 0.008) or 100 mg/kg pemetrexed (70.64 microg/ml versus 218.64 microg/ml; p = 0.001). At either dose, the AUC and the CL did not significantly differ according to the route of administration.

CONCLUSIONS

While intravenous and intrapleural administration of pemetrexed yielded similar AUC and CL, the intrapleural route yielded a significantly lower C(max). As Cmax is a determinant of pemetrexed toxicity, intrapleural administration might offer a means of widening the effective therapeutic index of the drug by improving tolerability. Future studies are needed to confirm this hypothesis in malignant pleural mesothelioma patients.

The development of phase I cancer trial methodologies: the use of pharmacokinetic and pharmacodynamic end points sets the scene for phase 0 cancer clinical trials

Although the concept of a phase 0 trial is a relatively new one, there has been a slowly increasing trend toward basing early clinical trial designs on pharmacokinetic and pharmacodynamic end points that has been developing over many years. This article will review the early cancer trial methodologies and the various techniques that have been used to refine them. Several illustrative examples will be presented showing their relevance to trial designs using pharmacodynamic end points and targeted agents. Some criteria for characterizing suitable phase 0 end points are suggested. Four trial designs that are essentially developed for cytotoxic agents using the maximal tolerated dose as an end point are described. Although these trials were not designed with the use of more sophisticated pharmacodynamic end points (such as the measurement of the effect of a targeted agent on its target), they have been developed to optimize the speed with which a dose needed to achieve a particular effect can be determined and are, to this extent, relevant to the design of studies with pharmacodynamic end points.

Pemetrexed: biochemical and cellular pharmacology, mechanisms, and clinical applications

Pemetrexed is a new-generation antifolate, approved for the treatment of mesothelioma and non-small cell lung cancer, currently being evaluated for the treatment of a variety of other solid tumors. This review traces the history of antifolates that led to the development of pemetrexed and describes the unique properties of this agent that distinguish it from other antifolates. These include (a) its very rapid conversion to active polyglutamate derivatives in cells that build to high levels and are retained for long intervals to achieve prolonged and potent inhibition of its major target enzyme thymidylate synthase, (b) its high affinity for three folate transporters, and (c) its marked sensitivity to the level of physiologic folates in cells. The latter results in the unique and paradoxical finding that when transport mediated by the major folate transporter (the reduced folate carrier) is impaired, pemetrexed activity is preserved. This is due to concurrent contraction of competing cellular physiologic folates and utilization of a novel second transport carrier for which pemetrexed has high affinity, recently identified as the proton-coupled folate transporter (PCFT). Laboratory studies are reviewed that raise the possibility of new approaches to the use of folic acid supplementation in clinical regimens with pemetrexed.

Clinical activity of pemetrexed: a multitargeted antifolate anticancer agent

Pemetrexed is a new generation antifolate anticancer agent that inhibits several folate-dependent enzymes required for production of DNA and RNA intermediates. Early studies showed significant hematologic and nonhematologic toxicities with this agent. However it was found that many of these toxicities related to functional folate status and could be markedly reduced through routine supplementation with folic acid and vitamin B(12), without adversely affecting efficacy. Phase III studies with pemetrexed have established a clinical role for this drug as a single agent in the second-line treatment of non-small cell lung cancer and in combination with cisplatin for the frontline treatment of unresectable malignant pleural mesothelioma. Clinical trials of pemetrexed alone or in combination with other chemotherapeutic agents have shown considerable activity in many tumor types including colorectal, pancreatic and breast cancer, and urothelial tumors.

A Dose Escalation Study of Gemcitabine plus Pemetrexed Administered Biweekly in Patients with Solid Tumors

PURPOSE

The study aimed to determine the maximum tolerated doses (MTDs) and identify the dose-limiting toxicities of the biweekly administration of pemetrexed plus gemcitabine in patients with solid tumors.

PATIENTS AND METHODS

Patients with advanced malignancies were treated with escalated doses of gemcitabine and pemetrexed (starting doses 1,250 and 300 mg/m(2), respectively) both given on days 1 and 15 in cycles of 4 weeks.

RESULTS

Forty-one patients were treated at 7 dose levels. The MTD was reached at the dose of 1,750 mg/m(2) for gemcitabine and 450 mg/m(2) for pemetrexed. Dose-limiting events were grade IV neutropenia, febrile neutropenia and treatment delay due to grade III hematological toxicities. One partial response in a pretreated patient with ovarian cancer was observed, while 4 other patients experienced stable disease.

CONCLUSIONS

The biweekly administration of gemcitabine plus pemetrexed at the recommended MTDs is safe, well tolerated and demonstrates antitumor activity which merits further evaluation in phase II studies.

New molecular targets and novel agents in the treatment of advanced urothelial cancer

Standard cytotoxic regimens for metastatic bladder cancer, such as gemcitabine/cisplatin or methotrexate, vinblastine, doxorubicin, and cipslatin (M-VAC), yield impressive overall response rates of 45% to 70%. Despite this, long-term, disease-free, overall survival is rare, and most patients eventually succumb to the disease. Much work has been undertaken evaluating the clinical and molecular factors associated with progressive bladder cancer, and this has, in turn, led to the development of both novel targets and agents. These include standard cytotoxics such as pemetrexed, an antifolate and antimetabolite agent that has demonstrated an overall response rate of 30% in early studies, and small-molecule tyrosine kinase inhibitors such as sunitinib, which will be studied as maintenance therapy for patients who respond to first-line chemotherapy. The evaluation of new targets and new agents in the midst of limited patient, logistical, and financial resources will be one of the more difficult challenges for investigators over the next several years.

Pemetrexed: a multitargeted antifolate

BACKGROUND

The US Food and Drug Administration approved pemetrexed in February 2004 for the treatment of malignant pleural mesothelioma (MPM) in combination with cisplatin in patients with unresectable disease or for whom curative surgery is not an option. Pemetrexed is the first agent approved for the treatment of MPM. In August 2004, pemetrexed was approved as a second-line, single-agent treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC).

OBJECTIVES

The goals of this article were to summarize the pharmacology, pharmacokinetics, efficacy, and safety of pemetrexed, and to review its current and potential roles in therapy for MPM, NSCLC, and other oncologic conditions.

METHODS

Relevant English-language literature was identified through searches of PubMed (1966-December 2004), International Pharmaceutical Abstracts, and the Proceedings of the American Society of Clinical Oncology (January 1995-December 2004). Search terms included pemetrexed, Alimta, MTA, multitargeted antifolate, LY231514, mesothelioma, MPM, non-small cell lung cancer, NSCLC, breast cancer, and pancreatic cancer. In addition to published literature, abstracts and posters presented at national and international scientific meetings were reviewed.

RESULTS

Myelosuppression was the predominant dose-limiting toxicity of pemetrexed reported in Phase I studies. Identification of the correlation between poor folate status and increased pemetrexed toxicity in a multivariate analysis led to the requirement of folic acid and vitamin B12 supplementation for patients in all pemetrexed studies, with a resulting noted decrease in pemetrexed toxicity. A single, multicenter, randomized Phase III trial compared the efficacy of pemetrexed in combination with cisplatin versus cisplatin alone in the treatment of MPM. Response rates were 41.3% in the pemetrexed/cisplatin combination and 16.7% with single-agent cisplatin (P < 0.001). The median survival time for the pemetrexed/cisplatin combination was significantly longer at 12.1 months versus 9.3 months for cisplatin alone (P = 0.02). One international, multicenter, randomized Phase III trial in patients with NSCLC compared single-agent pemetrexed versus docetaxel in patients previously treated with chemotherapy. Overall response rates (9.1% and 8.8%) and median survival (8.3 months and 7.9 months) did not differ between pemetrexed and docetaxel (P = 0.105 and P = 0.226, respectively). Hematologic adverse effects-grade 3/4 neutropenia (40.2% vs 5.3%; P < 0.001), febrile neutropenia (12.7% vs 1.9%; P < 0.001), and neutropenic infections (3.3% vs 0%; P = 0.004)-were significantly greater in the docetaxel-treated patients than in the pemetrexed-treated patients, as was alopecia (37.7% vs 6.4%; P < 0.001). Results of an international, multicenter Phase III trial of pemetrexed in combination with gemcitabine conducted in patients with pancreatic cancer indicate that the combination is no more efficacious than single-agent gemcitabine. Results in other disease states are still preliminary.

CONCLUSIONS

Pemetrexed is a multitargeted antifolate that has demonstrated antitumor activity in various tumor types as a single agent and in combination with other chemotherapeutic agents. Efficacy for the treatment of MPM in combination with cisplatin has been demonstrated, and approval as a second-line agent in NSCLC was based on response rate as a surrogate end point for survival. The addition of folic acid and vitamin B12 supplementation markedly reduced.

A phase I study of pemetrexed (LY231514) supplemented with folate and vitamin B12 in Japanese patients with solid tumours

The purpose of this study was to determine the maximum tolerated dose (MTD) and recommended dose (RD) of pemetrexed with folate and vitamin B12 supplementation (FA/VB₁₂) in Japanese patients with solid tumours and to investigate the safety, efficacy, and pharmacokinetics of pemetrexed. Eligible patients had incurable solid tumours by standard treatments, a performance status 0–2, and adequate organ function. Pemetrexed from 300 to 1200 mg m⁻² was administered as a 10-min infusion on day 1 of a 21-day cycle with FA/VB₁₂. Totally, 31 patients were treated. Dose-limiting toxicities were alanine aminotransferase (ALT) elevation at 700 mg m⁻², and infection and skin rash at 1200 mg m⁻². The MTD/RD were determined to be 1200/1000 mg m⁻², respectively. The most common grade 3/4 toxicities were neutropenia (grade (G) 3:29, G4:3%), leucopenia (G3:13, G4:3%), lympopenia (G3:13%) and ALT elevation (G3:13%). Pemetrexed pharmacokinetics in Japanese were not overtly different from those in western patients. Partial response was achieved for 5/23 evaluable patients (four with non-small cell lung cancer (NSCLC) and one with thymoma). The MTD/RD of pemetrexed were determined to be 1200/1000 mg m⁻², respectively, that is, a higher RD than without FA/VB₁₂ (500 mg m⁻²). Pemetrexed with FA/VB₁₂ showed a tolerable toxicity profile and potent antitumour activity against NSCLC in this study.

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 ≥ 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 nonsupplemented 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 ≥ 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 ≥ 40 mL/min. Additional studies are needed to define appropriate dosing for renally impaired patients receiving higher dose pemetrexed with vitamin supplementation.

Pemetrexed-associated urticarial vasculitis

Pemetrexed (Alimta, Eli Lilly and Company, Indianapolis, IN) is a structurally novel anti-folate agent. The United States Food and Drug Administration has approved pemetrexed for the treatment of patients with malignant pleural mesothelioma and previously treated patients with locally advanced or metastatic non-small cell lung cancer. In the phase III trials that led to its approval, rash was reported in 17 and 22% of patients receiving pemetrexed alone or in combination with cisplatin. However, little has been published about the characteristics of this rash or about its mechanism. In an attempt to contribute to the growing body of knowledge about this new agent, we describe a case in which a patient developed a rash secondary to urticarial vasculitis associated with pemetrexed.

Population pharmacokinetic analysis of ten phase II clinical trials of pemetrexed in cancer patients

PURPOSE

The objectives of these population pharmacokinetic analyses were to (1) assess the overall disposition of pemetrexed, (2) characterize between-patient and within-patient variability and identify influential covariates with respect to pemetrexed pharmacokinetics; and, (3) provide individual empirical Bayesian estimates of pharmacokinetic parameters for use in a subsequent pharmacokinetic/pharmacodynamic evaluation of neutropenia following pemetrexed administration.

PATIENTS AND METHODS

Data from 287 patients who received 441 cycles without folic acid or vitamin B12 supplementation during participation in one of ten phase II cancer trials were evaluated by population pharmacokinetic analysis using NONMEM. Starting doses were 500 or 600 mg pemetrexed per m2 body surface area, administered as 10-min intravenous infusions every 21 days (1 cycle). The model was developed using data from eight of the ten studies. Predictive performance was evaluated using data from the other two studies.

RESULTS

The population pharmacokinetics of pemetrexed administered as a 10-min intravenous infusion are well characterized by a two-compartment model. Typical values of total systemic clearance, central volume of distribution, distributional clearance, and peripheral volume of distribution were 91.6 ml/min, 12.9 l, 14.4 ml/min, and 3.38 l, respectively. Based on these parameter estimates, the terminal elimination half-life of pemetrexed was approximately 3.5 h. Renal function was identified as a covariate with respect to total systemic clearance, and body surface area as a covariate with respect to the central volume of distribution.

CONCLUSION

Total systemic exposure (AUC) for a given dose of pemetrexed increases as renal function decreases. Since pharmacodynamic analyses have shown that AUC and not C (max) is the primary determinant of neutropenic response to pemetrexed, this suggests that dose adjustments based on renal function, rather than body surface area, might be considered for pemetrexed.

Phase I/II Dose-Escalation Study of Pemetrexed plus Irinotecan in Patients with Advanced Colorectal Cancer

BACKGROUND

Pemetrexed and irinotecan have demonstrated antitumor activity as single agents in lung, pancreatic, breast, and colorectal cancer (CRC). The distinct mechanisms of action and patterns of resistance displayed by pemetrexed and irinotecan make them attractive agents for combination therapy.

PATIENTS AND METHODS

This phase I/II, nonrandomized, open-labeled, single-arm study was composed of 3 segments. The initial phase II portion of the study enrolled 23 patients with advanced CRC who had received 1 previous dose of 5-fluorouracil (5-FU)-based chemotherapy for advanced disease. Because of poorer than anticipated efficacy, a phase I dose-escalation study using vitamin supplementation (n = 12) was added to the original protocol. The phase II dose-escalation portion of the study enrolled 36 patients (64% with previous oxaliplatin-based therapy) who received pemetrexed 500 mg/m2 followed by irinotecan 300 mg/m2 on day 1, every 21 days.

RESULTS

For the 35 evaluable patients in the phase II dose-escalation study, the objective response rate was 11.4% (95% confidence interval, 3.2%-26.7%); there was 1 patient with a complete response, 3 with partial responses, and 17 with stable disease. Three of four responders had received previous oxaliplatin-based combination therapy. Grade 3/4 hematologic toxicities included leukopenia (5.6%), anemia (2.8%), and thrombocytopenia (2.8%). Grade 3/4 nonhematologic toxicities included diarrhea (11.1%), increased aminotransferase levels (8.3%), nausea (8.3%), febrile neutropenia (5.6%), vomiting (5.6%), and reduced creatinine clearance (2.8%).

CONCLUSION

Pemetrexed plus irinotecan appears to be at least as active as FOLFIRI (leucovorin/5-FU/irinotecan) for second-line therapy of CRC following 5-FU-based combination chemotherapy. Further studies are warranted.

New cytotoxic agents: a review of the literature

The goal of treatment for patients with advanced cancer is to prolong survival, control symptoms, and reduce disease-related complications. Despite the introduction of many cytotoxic agents during the past decade, only modest improvement in survival has been achieved. In order to urgently improve these situations, new cytotoxic agents as well as molecular-targeted agents are now under investigation. In this article, we reviewed the latest information regarding antitumor activity, toxicity, pharmacokinetics, and clinical application of the new cytotoxic agents.

Randomized phase II trial of three schedules of pemetrexed and gemcitabine as front-line therapy for advanced non-small-cell lung cancer

PURPOSE

A randomized three-arm phase II study was undertaken to evaluate the optimum administration schedule of pemetrexed and gemcitabine in chemotherapy-naïve patients with non-small-cell lung cancer.

PATIENTS AND METHODS

Patients were randomly assigned to three schedules of pemetrexed 500 mg/m2 plus gemcitabine 1,250 mg/m2, separated by a 90-minute interval, on a 21-day cycle as follows: schedule A, pemetrexed followed by gemcitabine on day 1 and gemcitabine on day 8; schedule B, gemcitabine followed by pemetrexed on day 1 and gemcitabine on day 8; and schedule C, gemcitabine on day 1 and pemetrexed followed by gemcitabine on day 8.

RESULTS

One hundred fifty-two eligible patients (schedule A, n = 59; schedule B, n = 31, and schedule C, n = 62) received a median of five (schedule A), two (schedule B), and four (schedule C) treatment cycles. Overall, 66% of patients experienced grade 3 or 4 neutropenia. Common grade 3 and 4 nonhematologic toxicities were dyspnea (11%), fatigue (16%), and transaminase elevation (9%). Schedule A seemed less toxic compared with schedule C (grade 3 or 4 events: 86% v 94%, respectively; P = .19; grade 4 events: 39% v 48%, respectively; P = .30). Schedule B was closed at interim analysis for inferior efficacy. Schedule A, with a confirmed response rate of 31% (95% CI, 20% to 45%), met the protocol-defined efficacy criteria, whereas schedule C, with a confirmed response rate of 16.1% (95% CI, 11% to 34%), did not. Median survival time and time to progression were 11.4 and 4.4 months, respectively, with no observable difference between the arms.

CONCLUSION

Pemetrexed and gemcitabine administered as outlined for schedule A met the protocol-defined efficacy criteria, was less toxic compared with the other treatment schedules, and should be further evaluated.

The evolution of cancer research and drug discovery at Lilly Research Laboratories

This review highlights the discovery and development of chemotherapy at Eli Lilly & Company over the past 30 years from the Vinca alkaloids-vincristine, vinblastine, and vindesine-to targeted therapy. During the late 1970s, Lilly began an exploration of new synthetic compounds based on solid tumor screening models. Several novel antimetabolites with the potential to treat solid tumors were identified. Two such agents, gemcitabine and pemetrexed, underwent clinical development and are now among Lilly's portfolio of approved anticancer drugs. Gemcitabine, a pyrimidine nucleoside that has a profound effect on DNA synthesis, has been approved for the treatment of pancreatic, non-small cell lung, bladder, and most recently, breast, and ovarian cancer. Pemetrexed, a novel antifolate with potent cytotoxic effects, is distinguished from other antifolates by virtue of its ability to inhibit multiple folate-dependent enzymes. Pemetrexed, given in combination with cisplatin, has been recently approved for the treatment of malignant pleural mesothelioma and as second-line treatment for non-small cell lung cancer. Spurred by advances in the understanding of cancer as a disease process, Lilly's anticancer drug program began to transition to a more "targeted" approach during the 1990s. These efforts have recently culminated in the identification and development of enzastaurin, a PKCbeta inhibitor with potent anti-angiogenic properties. Enzastaurin has shown promising single-agent activity in patients with relapsed diffuse large B-cell lymphoma and recurrent glioblastoma multiforme, and is an excellent candidate for combination with cytotoxic agents.

Pemetrexed/Oxaliplatin for First-Line Treatment of Patients with Advanced Colorectal Cancer: A Phase II Trial of the National Surgical Adjuvant Breast and Bowel Project Foundation Research Program

BACKGROUND

Pemetrexed and oxaliplatin have clinical activity as single agents in colorectal cancer (response rates, 10%-17%). In this study, these drugs were used in combination as first-line therapy in a group of patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Fifty-four evaluable patients were to receive pemetrexed (500 mg/m2) with folic acid and vitamin B12 supplementation and oxaliplatin (120 mg/m2) every 21 days for 6 cycles or until disease progression occurred. Patients with stable or responding disease could continue therapy beyond 6 cycles at the discretion of the investigator. Eligibility criteria included a diagnosis of untreated metastatic adenocarcinoma of the colon or rectum, measurable disease, Zubrod performance status <or=2, no adjuvant chemotherapy within 6 months, and >or=12 weeks life expectancy.

RESULTS

The confirmed clinical response rate (primary endpoint) was 29.6% (95% confidence interval [CI], 18%-48.6%), with 1 complete response and 15 partial responses. Median time to progression was 5.3 months (95% CI, 3.9-6.3 months), and median survival was 12.3 months (95% CI, 8.6-17 months). Grade 3/4 nadir neutropenia occurred in 33.3% of patients, and 3 patients experienced grade 3 febrile neutropenia or infection associated with grade 3/4 neutropenia. Grade 3/4 nadir thrombocytopenia was seen in 11.1% of patients. Only 4% of the patients developed grade 3/4 neurotoxicity.

CONCLUSION

This regimen of pemetrexed and oxaliplatin has activity in advanced colorectal cancer, and the toxicity profile suggests that escalation of the dose of pemetrexed in this combination may be possible.