Pemetrexed disodium in recurrent locally advanced or metastatic squamous cell carcinoma of the head and neck

An evaluation of pemetrexed in second-line treatment of non-small cell lung cancer

Pemetrexed is a novel antifolate antimetabolite that targets multiple folate-dependent enzymatic pathways and inhibits multiple enzymes involved in purine and pyrimidine synthesis. Its targets include pathways that, when amplified, are associated with reduced efficacy in conventional cytotoxic agents. As second-line treatment for advanced non-small cell lung cancer, (NSCLC) pemetrexed, when administered with folic acid and vitamin B12, has demonstrated comparable efficacy and a superior toxicity profile relative to docetaxel. A retrospective analysis of the Phase III trial of pemetrexed versus docetaxel shows a statistically significant longer toxicity-free survival time for pemetrexed compared with docetaxel. Newer targeted therapies, especially the epidermal growth factor receptor inhibitors gefitinib and erlotinib, have produced conflicting results and have only been compared with best supportive care and placebo. They should be compared directly to pemetrexed as second-line therapy in large, randomised studies of patients with advanced NSCLC. For patients with advanced recurrent NSCLC and good performance status who progress after first-line chemotherapy, pemetrexed should be considered as a new standard of care.

New approaches to enhance chemotherapy in SCCHN

Chemotherapy is the standard approach to the treatment of patients with recurrent and metastatic squamous cell carcinoma of the head and neck (SCCHN) and is also now a common component of treatment for patients with locoregionally advanced, non-metastatic disease. Cisplatin has for many years been the agent of choice, alone or in combination with other agents, particularly 5-FU. The advent of the taxanes, which demonstrate good non-clinical activity against SCCHN, spawned a series of investigations aimed at integrating these agents into treatment regimens. Molecular targeted agents, which do not demonstrate overlapping toxicities with commonly used chemotherapy agents for SCCHN, represent a promising avenue of investigation. The epidermal growth factor receptor (EGFR) is expressed both widely and at high levels in SCCHN and is associated with poor prognosis. The EGFR-directed monoclonal antibody (MAb) cetuximab (Erbitux) in combination with chemotherapy has shown some activity in the treatment of recurrent/metastatic disease both as first-line therapy and following cisplatin failure, and preliminary results suggest single-agent activity in platinum-resistant disease. Promising activity has also been observed with a number of other EGFR inhibitors, both MAbs and tyrosine kinase inhibitors.

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.

A phase IB study of the pharmacokinetics of gemcitabine and pemetrexed, when administered in rapid sequence to patients with advanced solid tumors

BACKGROUND

We have previously demonstrated that pemetrexed is clinically active when administered 90 min after gemcitabine in a phase I study. The present study was undertaken to evaluate the efficacy, toxicity, and pharmacokinetics of gemcitabine and pemetrexed when pemetrexed is administered immediately after gemcitabine.

PATIENTS AND METHODS

A total of 14 patients received 84 cycles of treatment. Gemcitabine 1250 mg/m(2) was administered on days 1 and 8 of each 21-day cycle, and pemetrexed 500 mg/m(2) on day 8 immediately following gemcitabine administration. Toxicities were graded according to the National Cancer Institute Common Toxicity Criteria and recorded as maximum grade per patient for all treatment cycles. Pharmacokinetic analyses of plasma gemcitabine and pemetrexed concentrations were performed.

RESULTS

Neutropenia was the most common severe toxicity. Non-hematologic toxicities, which included nausea, vomiting, fatigue, diarrhea, rash, and elevated transaminases were of mild-to-moderate severity. No increased toxicity was observed with this schedule in comparison to the previous phase I schedule. There was no pharmacokinetic interaction between the two drugs. One partial response was documented in a patient with non-small-cell lung cancer. Eight patients had disease stabilization for five or more cycles.

CONCLUSION

Gemcitabine immediately followed by pemetrexed is well tolerated and clinically active, and deserves further evaluation in phase II trials.

Chemotherapy for recurrent or metastatic squamous cell carcinoma of the head and neck

Recurrent and metastatic squamous cell carcinoma of the head and neck (SCCHN) are difficult problems and likely to become more challenging as concurrent chemotherapy and radiation are more widely used. Randomized studies reported in 1992 established the combination of cisplatin and infusional 5-fluorouracil (5-FU) as the reference regimen for chemotherapy-naive, good-performance status patients. Subsequently, a randomized study of 194 patients comparing cisplatin and 5-FU to cisplatin and paclitaxel found better tolerance, better pain relief, and improved quality of life with the newer regimen, but no survival differences (medians of 9 months) were detected. Phase II studies of a platinum/taxane combination with a third drug have reported response rates of greater than 50%, including 15% complete responses. A number of non-platinum-containing regimens are active in pretreated patients. Gefitinib has shown median survival times comparable to those achieved with cisplatin and paclitaxel, and appears especially promising for patients who recur after cytotoxic chemotherapy. Newer antifolates, agents that target or restore deficient p53, and other signal transduction inhibitors are under study.

Pemetrexed: a novel antifolate agent enters clinical practice

Pemetrexed (Alimta, Eli Lilly) is a multitargeted antifolate that inhibits at least three enzymes in the nucleic acid synthetic pathways. The US Food and Drug Administration recently approved pemetrexed, in combination with cisplatin, for the first-line treatment of advanced malignant pleural mesothelioma. Moreover, pemetrexed was recently shown to be as efficacious as docetaxel (Taxotere, Aventis) in the second-line treatment of non-small cell lung cancer, and its toxicity profile was preferable. The main toxicity seen with pemetrexed is myelosuppression, which is considerably reduced by coadministration of folic acid and vitamin B12. Multiple Phase II clinical trials have demonstrated that pemetrexed has promising single-agent activity in many other solid tumors, including head and neck, breast and colorectal cancers. Combination regimens consisting of pemetrexed and other chemotherapeutics or novel molecular-targeted agents are currently under investigation. Future studies will better define and likely expand the role of pemetrexed for the treatment of cancer.

Abarelix Pemetrexed

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column focuses on the commercially available and investigational agents used to treat malignant diseases and reviews issues related to the preparation, dispensing, and administration of cancer chemotherapy.

New cytotoxic and molecular-targeted therapies of head and neck tumors

PURPOSE OF REVIEW

The purpose of this review is to provide an update on novel medical treatments for head and neck cancer.

RECENT FINDINGS

Despite the continuing introduction of new cytotoxic agents, such as antimetabolites (capecitabine, pemetrexed), and topoisomerase I inhibitors, the management of advanced head and neck cancer remains challenging. Epidermal growth factor receptor is an appealing target for novel therapies in head and neck cancer. Several rational approaches have been designed to abrogate epidermal growth factor receptor function, among which the development of small molecules, such as gefitinib or erlotinib, that inhibit tyrosine kinase activity, therefore abrogating the receptor's catalytic activity, autophosphorylation, and its engagement with signal transducers. The development of monoclonal antibodies, such as cetuximab, directed against the receptor's extracellular domain and competing for the binding of receptor ligands is another antireceptor strategy, because it induces epidermal growth factor receptor downregulation from the tumor cell surface. Gefitinib has been evaluated in a phase II study in head and neck cancer, at a dose of 500 mg/day. In this study, a 53% disease control rate was achieved, with a low toxicity. Currently, a phase II study at a dose of 250 mg/day is ongoing. A phase II study of erlotinib in advanced head and neck cancer has provided similar results to those of gefitinib, with a 46% control rate and an acceptable toxicity. Phase I studies of cetuximab have been carried out in advanced head and neck cancer, mainly combining the drug with chemotherapy or radiotherapy. Three phase II studies have evaluated the combination of cetuximab with platinum-based chemotherapy in pretreated patients with recurrent/metastatic head and neck cancer, with a control rate ranging from 29 to 66%. A phase III placebo-controlled trial has shown that the addition of cetuximab to cisplatin does not significantly improve median progression-free survival, despite a difference in the response rate between the two arms. Other molecular-targeted approaches in head and neck cancer include farnesyl transferase inhibitors, cell cycle regulators, and gene therapy.

SUMMARY

Novel targeted therapies are highly appealing in advanced head and neck cancer, and the most clever way to use them is a matter of intense investigation.

Classification of anticancer drugs—a new system based on therapeutic targets

The arrival of a great number of new antineoplastic agents has made it necessary to reclassify all of them. Anticancer drugs may act at different levels: cancer cells, endothelium, extracellular matrix, the immune system or host cells. The tumour cell can be targeted at the DNA, RNA or protein level. Most classical chemotherapeutic agents interact with tumour DNA, whereas monoclonal antibodies and small molecules are directed against proteins. The endothelium and extracellular matrix may be affected also by specific antibodies and small molecules.

Phase II study of pemetrexed disodium (Alimta®) administered with oral folic acid in patients with advanced gastric cancer

BACKGROUND

The aim of this study was to assess the activity of pemetrexed in patients with advanced gastric cancer.

PATIENTS AND METHODS

Thirty-eight eligible patients (median age 60 years) received pemetrexed 500 mg/m(2) every 3 weeks. Since toxicity was considerable in the first six patients, the protocol was amended to supplement subsequent patients with oral folic acid (5 mg/day on days -2 to +2 of every cycle).

RESULTS

Among 36 stage IV patients evaluable for efficacy (six non-supplemented\30 supplemented), there were two complete and six partial responses. The response rate was 21% (95% confidence interval 8% to 32%) according to intention-to-treat analysis. All responding patients were in the supplemented group. The median duration of response was 4.6 months and the median survival was 7.8 months. Five of six non-supplemented patients (83%) developed grade 3/4 neutropenia; two (33%) unsupplemented patients discontinued; two (33%) patients died due to toxicity. In the supplemented group, 12 of 32 patients (37%) had grade 3/4 neutropenia. None of the supplemented patients discontinued treatment due to hematological toxicity. Severe non-hematological toxicities were infrequent.

CONCLUSIONS

The activity of pemetrexed is promising in light of the tumor burden in these patients (all patients were stage IV and 39% had three or more organs involved). Toxicities were remarkably decreased with folic acid supplementation. Combination studies are warranted.

Phase II study of pemetrexed in breast cancer patients pretreated with anthracyclines

BACKGROUND

To assess antitumor activity and toxicity of pemetrexed in metastatic breast cancer (MBC) patients previously treated with anthracyclines.

PATIENTS AND METHODS

Seventy-seven MBC patients from 12 European institutions were entered into the study. Seventy-two patients were considered evaluable for response and toxicity. Forty-two patients were classified as anthracycline-failure (relapse >30 days after completion of a prior anthracycline regimen) and 30 as anthracycline-refractory (progression within 30 days after anthracycline therapy). Pemetrexed 600 mg/m(2) was administered intravenously every 3 weeks until progressive disease or unacceptable toxicity.

RESULTS

There were three complete and 12 partial responders [response rate 21% (95% confidence interval 12%)]. Response rates in the anthracycline-failure and anthracycline-refractory groups were 24% and 17%, respectively. A subset of 31 patients pretreated with anthracyclines and taxanes had a response rate of 26%. Median duration of response and median survival were 5.5 and 10.7 months, respectively (13 months in the failure group and 5.7 months for refractory). Grade 3/4 toxicities included neutropenia and thrombocytopenia in 56% and 19% of patients, respectively. Nine patients (12%) experienced neutropenic fever. Grade 3/4 non-hematological toxicities included skin rash (10%), nausea (12%), fatigue (10%) and stomatitis (5%).

CONCLUSION

Our trial demonstrates pemetrexed to be active in breast cancer, with manageable toxicity. Activity of pemetrexed did not appear to be adversely affected by prior taxane, 5-fluorouracil or endocrine treatments.

Review of a promising new agent--pemetrexed disodium

Pemetrexed disodium (ALIMTa, [pemetrexed], LY231514; Eli Lilly and Company; Indianapolis, IN), a novel antifolate antimetabolite with multiple enzyme targets involved in both pyrimidine and purine synthesis, has entered clinical trials due to its favorable pleclinical profile. Many studies utilizing the drug, as a single or combination agent, are currently ongoing, including Phase III trials in mesothelioma, nonsmall cell lung carcinoma (NSCLC) and pancreatic cancer. Promising feasibility and activity data have been obtained with pemetrexed in combination with platinum compounds and gemcitabine. The supplementation with daily oral folate could reduce the incidence of hematologic toxicities while preserving the antitumor activity of pemetrexed.

Pemetrexed (Alimta): a novel multitargeted antifolate agent

Pemetrexed (Alimta) is a novel, multitargeted antifolate that inhibits at least three of the enzymes involved in folate metabolism, and purine and pyrimidine synthesis. These enzymes are thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyltransferase. Pemetrexed has demonstrated broad antitumor activity in Phase II trials in a wide variety of solid tumors, including mesothelioma, non-small cell lung, breast, cervical, colorectal, head and neck, and bladder cancers. Promising activity has also been demonstrated when pemetrexed is combined with cisplatin and gemcitabine (Gemzar). A pivotal Phase III study in mesothelioma has been presented. This study indicates the superiority of pemetrexed in combination with cisplatin versus cisplatin alone in this disease. The most significant toxicities of pemetrexed, myelosuppression and mucositis have been significantly ameliorated by folate and vitamin B12 supplementation. More importantly, vitamin supplementation has not demonstrated any adverse efficacy. This review discusses the biochemistry and clinical activity of pemetrexed.

Novel antifolate drugs

Antimetabolites are active chemotherapeutic agents for many solid tumor and hematologic malignancies. Folate antagonists, purine analogues, and pyrimidine analogues are the three main categories of antimetabolites. Methotrexate, the most studied folate antagonist, is effective in many malignancies. Methotrexate inhibits dihydrofolate reductase, which leads to accumulation of polyglutamated folates, causing further inhibition of thymidylate synthase and glycinamide ribonucleotide formyltransferase. Subsequently, the lack of reduced folate substrates impairs synthesis of purine nucleotides, thymidylate, and certain amino acids, which can lead to cell death. However, methotrexate resistance develops through several mechanisms, including decreased folate carrier-mediated membrane transport, dihydrofolate reductase gene amplification, specific transcription-translational modifications, and downregulation of intracellular methotrexate polyglutamation. Antifolate drug development has focused on agents designed to overcome different aspects of methotrexate resistance. This article reviews the enzymatic targets for antifolates, describes the known mechanisms of antifolate resistance, and summarizes the current development of novel antifolate agents. Discussed specifically are trimetrexate, edatrexate, raltitrexed, pemetrexed, ZD9331, lometrexol, LY309887, GW1843, OSI-7904(L), and nolatrexed, all of which have unique clinical pharmacology and are in various stages of development. The toxicity of antifolates has been sporadic and difficult to predict clinically. Supplementation with folic acid and vitamin B(12) has been shown to reduce the toxicity of pemetrexed without affecting efficacy and has increased the therapeutic index for this novel agent.