Result of two randomized trials comparing nolatrexed (Thymitaq) versus methotrexate in patients with recurrent head and neck cancer

In silico and in vitro assessment of drugs potentially causing adverse effects by inhibiting CYP17A1

Cytochrome P450 enzymes (CYPs) play a crucial role in the metabolism and synthesis of various compound classes. While drug-metabolizing CYP enzymes are frequently investigated as anti-targets, the inhibition of CYP enzymes involved in adrenal steroidogenesis is not well studied. The steroidogenic enzyme CYP17A1 is a dual-function enzyme catalyzing hydroxylase and lyase reactions relevant for the biosynthesis of adrenal glucocorticoids and androgens. Inhibition of CYP17A1-hydroxylase leads to pseudohyperaldosteronism with subsequent excessive mineralocorticoid receptor activation, hypertension and hypokalemia. In contrast, specific inhibition of the lyase function might be beneficial for the treatment of prostate cancer by decreasing adrenal androgen levels. This study combined in silico and in vitro methods to identify drugs inhibiting CYP17A1. The most potent CYP17A1 inhibitors identified are serdemetan, mocetinostat, nolatrexed, liarozole, and talarozole. While some of these drugs are currently under investigation for the treatment of various cancers, their potential for the treatment of prostate cancer is yet to be explored. The DrugBank database was screened for CYP17A1 inhibitors, to increase the awareness for the risk of drug-induced pseudohyperaldosteronism and to highlight drugs so far unknown for their potential to cause side effects resulting from CYP17A1 inhibition.

Comparison of Second-Line Treatments for Patients with Platinum-Resistant Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma: A Systematic Review and Bayesian Network Meta-Analysis

Simple Summary

Which second-line treatment is the optimal choice for patients with platinum-resistant recurrent or metastatic head and neck squamous cell carcinoma remains unclear. To inform clinical decisions, we performed a network meta-analysis and systematic review to assess the relative efficacy and safety of second-line treatments for patients with platinum-resistant recurrent or metastatic head and neck squamous cell carcinoma. By synthesizing all available controlled trial evidence, PD-1 inhibitors significantly improved the overall survival, objective response rate, and treatment tolerance compared to the standard of care (docetaxel, methotrexate, or cetuximab). Afatinib presented a better progression-free survival and objective response rate than the standard of care. Compared with afatinib, PD-1 inhibitors had a better overall survival but a worse progress-free survival.

Abstract

Several new drugs and combination strategies can be used to treat patients with recurrent or metastatic head and neck squamous cell carcinoma in the second-line treatment. Questions regarding the relative efficacy and safety of any two of the multiple second-line treatment strategies have emerged. This study aims to compare second-line treatments for patients with platinum-resistant recurrent or metastatic head and neck squamous cell carcinoma. Medline, Embase, and the Cochrane Central Register of Controlled Trials were searched to identify relevant articles. Direct and indirect evidence in terms of the objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and treatment-related adverse events grade ≥ 3 (grade ≥ 3 trAE) were analyzed in this Bayesian network meta-analysis. A total of twenty-three trials involving 5039 patients were included. These studies compared 20 different treatments, including the standard of care (SOC: docetaxel, methotrexate, or cetuximab), PD-1 inhibitors (nivolumab or pembrolizumab), durvalumab, tremelimumab, durvalumab + tremelimumab, palbociclib + SOC, tivantinib + SOC, sorafenib + SOC, EMD1201081 + SOC, vandetanib + SOC, PX-866 + SOC, 5-fluorouracil + SOC, cixutumumab + SOC, gefitinib + SOC, cabazitaxel, nolatrexed, duligotuzumab, zalutumumab, gefitinib, and afatinib. Among the currently available treatment options, compared to the standard of care (SOC: docetaxel, methotrexate, or cetuximab), the PD inhibitor significantly improved OS, ORR, and grade ≥ 3 trAE. Afatinib presented a better PFS and ORR than the SOC. Compared with afatinib, the PD-1 inhibitor had a better OS but a worse PFS. In conclusion, compared to the SOC, the PD-1 inhibitor significantly improved the OS, ORR, and grade ≥ 3 trAE. Afatinib presented a better PFS and ORR than the SOC. Compared with afatinib, the PD-1 inhibitor had a better OS but a worse PFS.

Regulations of expressions of rat/human sulfotransferases by anticancer drug, nolatrexed, and micronutrients

Cancer is related to the cellular proliferative state. Increase in cell-cycle regulatory function augments cellular folate pool. This pathway is therapeutically targeted. A number of drugs influences this metabolism, that is, folic acid, folinic acid, nolatrexed, and methotrexate. Our previous study showed methotrexate influences on rat/human sulfotransferases. Present study explains the effect of nolatrexed (widely used in different cancers) and some micronutrients on the expressions of rat/human sulfotransferases. Female Sprague-Dawley rats were treated with nolatrexed (01-100 mg/kg) and rats of both sexes were treated to folic acid (100, 200, or 400 mg/kg) for 2-weeks and their aryl sulfotransferase-IV (AST-IV; β-napthol sulfation) and sulfotransferase (STa; DHEA sulfation) activities, protein expression (western blot) and mRNA expression (RT-PCR) were tested. In human-cultured hepatocarcinoma (HepG2) cells nolatrexed (1 nM-1.2 mM) or folinic acid (10 nM-10 μM) were applied for 10 days. Folic acid (0-10 μM) was treated to HepG2 cells. PPST (phenol catalyzing), MPST (dopamine and monoamine), DHEAST (dehydroepiandrosterone and DHEA), and EST (estradiol sulfating) protein expressions (western-blot) were tested in HepG2 cells. Present results suggest that nolatrexed significantly increased sulfotransferases expressions in rat (protein, STa, F = 4.87, P < 0.05/mRNA, AST-IV, F = 6.702, P < 0.014; Student's t test, P < 0.01-0.05) and HepG2 cells. Folic acid increased sulfotransferases activity/protein in gender-dependant manner. Both folic and folinic acid increased several human sulfotransferases isoforms with varied level of significance (least or no increase at highest dose) in HepG2 cells pointing its dose-dependent multiphasic responses. The clinical importance of this study may be furthered in the verification of sulfation metabolism of several exogenous/endogenous molecules, drug-drug interaction and their influences on cancer pathophysiological processes. Further studies are necessary.

The Optimal Second-Line Systemic Treatment Model for Recurrent and/or Metastatic Head and Neck Squamous Cell Carcinoma: A Bayesian Network Meta-Analysis

Background

The optimal second-line systemic treatment model for recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) remains controversial. A Bayesian network meta-analysis (NMA) was performed to address this issue with regard to efficacy and toxicity.

Methods

By searching MEDLINE (via PubMed), Embase, the Cochrane Central Register of Controlled Trials and Web of Science, we extracted eligible studies. Efficacy, represented as overall survival (OS) and progression-free survival (PFS), and overall toxicity, represented as ≥ grade 3 severe acute events (sAE), were assessed to compare the following 7 treatment models through an NMA: standard-of-care therapy (SoC), single targeted therapy different from SoC (ST), double targeted therapy (DT), targeted therapy combined with chemotherapy (T+C), single immune checkpoint inhibitor therapy (SI), double immune checkpoint inhibitor therapy (DI) and single chemotherapy different from SoC (SC). Rank probabilities according to the values of the surface under the cumulative ranking curve (SUCRA) were separately determined for efficacy and toxicity.

Results

In total, 5285 patients from 24 eligible studies were ultimately screened, with 5184, 4532 and 4026 involved in the NMA of OS, PFS and sAE, respectively. All qualifying studies were absent from first-line immune checkpoint inhibitor therapy. In terms of OS, SI was superior to the other treatments, followed by DI, ST, T+C, SoC, DT and SC. Other than SI and SC, all treatments tended to be consistent, with hazard ratios (HRs) close to 1 between groups. For PFS, ST ranked first, while DT ranked last. For the toxicity profiles, compared with the other models, SI resulted in the lowest incidences of sAE, with statistical significance over SoC (odds ratio [OR] 0.31, 95% credible interval [CrI] 0.11 to 0.90), ST (OR 0.23, 95% CrI 0.06 to 0.86) and DT (OR 0.11, 95% CrI 0.02 to 0.53), while DT was the worst. When the SUCRA values of OS and sAE were combined, a cluster plot illustrated the superiority of SI, which demonstrated the best OS and tolerability toward sAE.

Conclusion

For R/M HNSCC patients without immune checkpoint inhibitors in the first-line setting, SI may serve as the optimal second-line systemic treatment model, demonstrating the best OS and least sAE.

Systemic Therapy in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma- A Systematic Review and Meta-Analysis

BACKGROUND

The most effective regimen is unclear for patients with recurrent or metastatic head and neck squamous cell carcinomas (R/M HNSCC). We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating only systemic therapy for R/M HNSCC.

METHODS

This systematic review followed PRISMA and the Cochrane Collaboration Handbook for Systematic Reviews of Interventions. Endpoints included overall survival (OS), progression-free survival (PFS) and overall response rates (ORR).

RESULTS

55 RCTs from 1990-November 2019 qualified for review (n=12132). Only PD-1/PDL-1 inhibitors increased OS in R/M HNSCC platinum-resistant disease against their control (HR = 0·79, 95%CI 0·70-0.90, p<0·001), especially for PD-L1 ≥ 1% expressing tumours (HR = 0·72, 95%CI 0·60-0·86, p<0·001). PFS was prolonged for anti-EGFR agents against methotrexate when used in a second line setting (HR = 0·74, 95 %CI 0·62-0·87, p=0·001), and when cetuximab (HR = 0·60, 95%CI 0·49-0·72, p<0·0001) and panitumumab (HR = 0·76, 95%CI 0·65-0·89, p=0·001) were introduced to platinum-based regimens for first-line treatment.

CONCLUSIONS

PD-1/PD-L1 inhibitors may represent the future of R/M HNSCC treatment. However, EGFR inhibitors may still play improve clinical outcomes.

Clinical outcomes with therapies for previously treated recurrent/metastatic head-and-neck squamous cell carcinoma (R/M HNSCC): A systematic literature review

OBJECTIVES

A wide range of objective response rates (ORRs: 0-53%) among available treatments in patients with R/M HNSCC with progression on or after platinum-based chemotherapy (PBT) renders treatment selection a challenge. This systematic literature review (SLR) was intended to aid clinical decision-making by classifying historical studies to accurately characterize the response in second-line (progression on/after platinum-based therapy), and third-line (progression on/after platinum and cetuximab/other drug) settings.

METHODS

SLR was performed to characterize the ORR, duration of response (DOR), progression-free survival (PFS) and overall survival (OS) with therapies recommended by the National Comprehensive Cancer Network (NCCN) guidelines. Clinical trials published in English between January 1, 1985, and September 30, 2016 were identified by searching the PubMed (Medline), Cochrane, and Embase databases.

RESULTS

The SLR identified 34 key studies in second-line R/M HNSCC patients, and one of these included a third-line patient cohort. However, several studies did not enrol a strictly second-line population. Response in a true second-line setting was elucidated by categorizing the studies using a novel framework defined according to the extent to which enrolled patients were second-line. Only seven studies were strictly second-line, with an estimated pooled ORR of 4% (95% CI = 2-8%; N = 414) for methotrexate and 11% (95% CI = 7-15%; N = 235) for cetuximab, and a reported ORR of 14% (N = 78) from a single study of paclitaxel. The median DOR was limited with cetuximab (∼4 months) and paclitaxel (∼7 months), and not reported for methotrexate. Median PFS or time to progression (TTP) ranged from 1.7 to 3.5 months, and median OS from 4.3 to 6.7 months. The ORR in the only third-line study was 0% (95% CI = 0-7; N = 53) for the platinum + cetuximab combination.

CONCLUSION

These findings emphasize the historically bleak prognoses in patients with R/M HNSCC following PBT progression. Anti-PD-1 therapies, namely pembrolizumab and nivolumab, represent novel treatment options that may improve clinical outcomes.

Metastatic nasopharyngeal carcinoma outcomes in patients on cisplatin with nolatrexed or 5-fluorouracil

BACKGROUND

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors in southern China. In this study, we compared the clinical efficacy and toxicity of cisplatin with nolatrexed (LP) or 5-fluorouracil (FP) for NPC.

PATIENTS AND METHODS

33 patients with metastatic NPC were randomized to the LP and FP regimens. The LP regimen consisted of continuous intravenous infusions of 740 mg/m(2) nolatrexed on days 1-5 and 25 mg/m(2) intravenous cisplatin on days 2-4. The FP regimen consisted of continuous intravenous infusions of 600 mg/m(2) 5-fluorouracil on days 1-5 and 25 mg/m(2) intravenous cisplatin on days 2-4. Cycles were repeated every 3 weeks until disease progression or completion of a total of 6 courses.

RESULTS

There were no significant differences in the response rates (RR), disease control rates (DCR), times to progression (TTP), and median survival times (MST) between the regimens. The toxicities of the two regimens were mostly grade I/II, but the stomatitis incidence in the patients on the LP regimen was significantly lower than that on the FP regimen.

CONCLUSIONS

The efficacy of the LP regimen was similar to that of the FP regimen. The LP regimen had lower toxicity.

Palliative low dose fortnightly methotrexate in oral cancers: Experience at a rural cancer centre from India

CONTEXT

Palliative fortnightly chemotherapy in oral cancers.

AIMS

We present our experience with a regimen employing fortnightly (once in 2 weeks) injectable methotrexate (MTX) (40 mg/m(2) ) in a predominantly elderly cohort of patients with carcinoma of oral cavity and oropharynx.

SETTINGS AND DESIGN

Retrospective chart review conducted at a rural cancer center in India.

MATERIALS AND METHODS

All patients with oral cavity and oropharyngeal cancers started on treatment with fortnightly injectable MTX (40 mg/m(2) ) between 01/01/2011 and 31/12/2011.

STATISTICAL ANALYSIS USED

The factors analyzed included the duration of disease control, pain control, overall survival and progression free survival which were evaluated using the Kaplan Meier method.

RESULTS

A total of 60 patients with a median age of 66.5 years were analyzed. Majority of the patients had poor nutritional status, performance status or co-morbidities. MTX was given for recurrent disease in 19 patients and after initial palliative radiotherapy in 41 patients. The median number of cycles delivered was nine. Grade 3/4 toxicities were seen in 2 patients only. Disease control rate at the end of treatment was seen in 33 (55%) patients. Median overall survival was 34 weeks (interquartile range: 17-50 weeks).

CONCLUSIONS

The fortnightly regimen of MTX was well-tolerated and showed a good clinical activity in this elderly cohort of patients with advanced oral cavity and oropharyngeal cancers.

Fragment-based discovery of novel thymidylate synthase leads by NMR screening and group epitope mapping

Solution-state nuclear magnetic resonance (NMR) is a versatile tool for the study of binding interactions between small molecules and macromolecular targets. We applied ligand-based NMR techniques to the study of human thymidylate synthase (hTS) using known nanomolar inhibitors and a library of small molecule fragments. Screening by NMR led to the rapid identification of ligand pairs that bind in proximal sites within the cofactor-binding pocket of hTS. Screening hits were used as search criteria within commercially available sources, and a subset of catalog analogs were tested for potency by in vitro assay and binding affinity by quantitative saturation transfer difference (STD)-NMR titration. Two compounds identified by this approach possess low micromolar affinity and potency, as well as excellent binding efficiency against hTS. Relative binding orientations for both leads were modeled using AutoDock, and the most likely bound conformations were validated using experimentally derived STD-NMR binding epitope data. These ligands represent novel starting points for fragment-based drug design of non-canonical TS inhibitors, and their binding epitopes highlight important and previously unexploited interactions with conserved residues in the cofactor-binding site.

Phase III study of gefitinib compared with intravenous methotrexate for recurrent squamous cell carcinoma of the head and neck [corrected]

PURPOSE

To compare survival in patients with recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN) treated with gefitinib 250 or 500 mg/day or standard methotrexate.

PATIENTS AND METHODS

Four hundred eighty-six patients with recurrent SCCHN were randomly assigned to oral gefitinib 250 mg/day, gefitinib 500 mg/day, or methotrexate 40 mg/m(2) intravenously weekly. Primary end point was overall survival, secondary end points were objective response rate (ORR), safety, symptom improvement, and quality of life (QOL). Exploratory end points included association of efficacy with epidermal growth factor receptor gene copy number and other biomarkers.

RESULTS

Neither gefitinib 250 nor 500 mg/day improved overall survival compared with methotrexate (hazard ratio [HR], 1.22; 95% CI, 0.95 to 1.57; P = .12; and HR, 1.12; 95% CI, 0.87 to 1.43; P = .39, respectively). In the gefitinib 250 mg/day, 500 mg/day, and methotrexate groups, respectively, median overall survival was 5.6, 6.0, and 6.7 months; ORRs (Response Evaluation Criteria in Solid Tumors) were 2.7%, 7.6% and 3.9%, with no statistically significant difference between either gefitinib arm and methotrexate. No unexpected adverse events were observed, except for tumor hemorrhage-type events with gefitinib (8.9%, gefitinib 250 mg/day; 11.4%, gefitinib 500 mg/day; 1.9%, methotrexate). QOL improvement rates (Functional Assessment of Cancer Therapy-Head & Neck total score) were 13.4%, 18.0%, and 6.0% for gefitinib 250 mg/day, 500 mg/day, and methotrexate, respectively.

CONCLUSION

In patients with recurrent or metastatic SCCHN, while responses with gefitinib were seen, neither gefitinib 250 nor 500 mg/day improved overall survival compared with methotrexate. With the exception of tumor hemorrhage-type events with gefitinib, the adverse event profiles were generally consistent with those previously observed.

[Cancer chemotherapy of the upper aerodigestive tract]

Tumours of the upper aerodigestive tract represent the sixth most frequent kind of cancer in France and throughout the world. If the localised forms may be controlled in the long run in two thirds of cases by surgery or radiotherapy, only one third of locally advanced forms are accessible to a cure after association from radiotherapy and chemotherapy. Besides, with a median of survival less than six months, metastatic tumours present a catastrophic spontaneous prognosis among patients with a medical ground that is often heavily deteriorated by prolonged exposure to alcohol and tobacco. Thus, there is a necessity to implement adapted therapeutic strategies to each patient and based on satisfactory proof levels of effectiveness. Optimisation of existing chemotherapy protocols and development of new therapies, in particular of targeted therapies, remain an important objective in the hope to improve results of treatments in locally advanced and metastatic cancers of the oral cavity.

Phase III randomized controlled trial comparing the survival of patients with unresectable hepatocellular carcinoma treated with nolatrexed or doxorubicin

PURPOSE

The study objective was to compare the overall survival (OS) of patients with unresectable or metastatic hepatocellular carcinoma (HCC) treated with nolatrexed (NOL) or doxorubicin (DOX).

PATIENTS AND METHODS

Patients from North America, Europe, and South Africa (N = 445) with HCC were randomly assigned to receive NOL or DOX. Eligible patients had Karnofsky performance status (KPS) > or = 60%, Cancer of the Liver Italian Program (CLIP) score < or = 3, and adequate organ function. Primary end point was OS. Secondary end points included progression-free survival (PFS), objective response rates, and safety. The treatment groups were well-balanced with regards to age, sex, ethnic origin, and underlying liver disease. Randomization was stratified according to KPS and CLIP score.

RESULTS

At the time of the final analysis, 377 patients had died. Median OS was 22.3 weeks for NOL and 32.3 weeks for DOX (P = .0068). The hazard ratio was 0.753 in favor of DOX. Objective response rate (complete response [CR] plus partial response [PR]) was 1.4% for NOL and 4.0% for DOX. Median PFS was 12 weeks for NOL and 10 weeks for DOX (P = .7091). Median time to treatment failure was 8.4 weeks for NOL and 9.1 weeks for DOX (P = .0969). Grade 3 and 4 stomatitis, vomiting, diarrhea, and thrombocytopenia were more common in the NOL arm. Alopecia was more common in the DOX arm. More patients were withdrawn from study for toxicity in the NOL arm than in the DOX arm.

CONCLUSION

NOL showed minimal activity in this phase III trial. Further exploration at this dose and schedule in HCC is not warranted.

Molecular basis of antifolate resistance

Folates play a key role in one-carbon metabolism essential for the biosynthesis of purines, thymidylate and hence DNA replication. The antifolate methotrexate has been rationally-designed nearly 60 years ago to potently block the folate-dependent enzyme dihydrofolate reductase (DHFR) thereby achieving temporary remissions in childhood acute leukemia. Recently, the novel antifolates raltitrexed and pemetrexed that target thymidylate synthase (TS) and glycineamide ribonucleotide transformylase (GARTF) were introduced for the treatment of colorectal cancer and malignant pleural mesothelioma. (Anti)folates are divalent anions which predominantly use the reduced folate carrier (RFC) for their cellular uptake. (Anti)folates are retained intracellularly via polyglutamylation catalyzed by folylpoly-gamma-glutamate synthetase (FPGS). As the intracellular concentration of antifolates is critical for their pharmacologic activity, polyglutamylation is a key determinant of antifolate cytotoxicity. However, anticancer drug resistance phenomena pose major obstacles towards curative cancer chemotherapy. Pre-clinical and clinical studies have identified a plethora of mechanisms of antifolate-resistance; these are frequently associated with qualitative and/or quantitative alterations in influx and/or efflux transporters of (anti)folates as well as in folate-dependent enzymes. These include inactivating mutations and/or down-regulation of the RFC and various alterations in the target enzymes DHFR, TS and FPGS. Furthermore, it has been recently shown that members of the ATP-binding cassette (ABC) superfamily including multidrug resistance proteins (MRP/ABCC) and breast cancer resistance protein (BCRP/ABCG2) are low affinity, high capacity ATP-driven (anti)folate efflux transporters. This transport activity is in addition to their established facility to extrude multiple cytotoxic agents. Hence, by actively extruding antifolates, overexpressed MRPs and/or BCRP confer antifolate resistance. Moreover, down-regulation of MRPs and/or BCRP results in decreased folate efflux thereby leading to expansion of the intracellular folate pool and antifolate resistance. This chapter reviews and discusses the panoply of molecular modalities of antifolate-resistance in pre-clinical tumor cell systems in vitro and in vivo as well as in cancer patients. Currently emerging novel strategies for the overcoming of antifolate-resistance are presented. Finally, experimental evidence is provided that the identification and characterization of the molecular mechanisms of antifolate-resistance may prove instrumental in the future development of rationally-based novel antifolates and strategies that could conceivably overcome drug-resistance phenomena.

The role of multidrug resistance efflux transporters in antifolate resistance and folate homeostasis

Members of the ATP-binding cassette (ABC) transporters including P-glycoprotein (Pgp/ABCB1), multidrug resistance proteins (MRPs/ABCC) as well as breast cancer resistance protein (BCRP/ABCG2) function as ATP-dependent drug efflux transporters, which form a unique defense network against multiple chemotherapeutic drugs and cellular toxins. Among antitumor agents is the important group of folic acid antimetabolites known as antifolates. Antifolates such as methotrexate (MTX), pemetrexed and raltitrexed exert their cytotoxic activity via potent inhibition of folate-dependent enzymes essential for purine and pyrimidine nucleotide biosynthesis and thereby block DNA replication. Overexpression of MRPs and BCRP confers resistance upon malignant cells to various hydrophilic and lipophilic antifolates. Apart from their central role in mediating resistance to antifolates and other anticancer drugs, MRPs and BCRP have been recently shown to transport naturally occurring reduced folates. This was inferred from various complementary systems as follows: (a) Cell-free systems including ATP-dependent uptake of radiolabeled folate/MTX into purified inside-out membrane vesicles from stable transfectants and/or cells overexpressing these transporters, (b) Decreased accumulation of radiolabeled folate/MTX in cultured tumor cells overexpressing these transporters, as well as (c) In vivo rodent models such as Eisi hyperbillirubinemic rats (EHBR) that hereditarily lack MRP2 in their canalicular membrane and thereby display a bile that is highly deficient in various reduced folate cofactors and MTX, when compared with wild type Sprague-Dawley (SD) rats. In all cases, these folate/antifolate transporters functioned as high capacity, low affinity ATP-driven exporters. While the mechanism of cellular retention of (anti)folates is mediated via (anti)folylpolyglutamylation, certain efflux transporters including MRP5 (ABCC5) and BCRP were shown to transport both mono-, di- as well as triglutamate derivatives of MTX and folic acid. Furthermore, overexpression of MRPs and BCRP has been shown to result in decreased cellular folate pools, whereas loss of ABC transporter expression brought about a significant expansion in the intracellular reduced folate pool. The latter finding has important implications to antifolate-based chemotherapy as an augmented cellular folate pool results in a significant level of resistance to certain antifolates. Hence, the aims of the present review are: (a) To summarize and discuss the cumulative evidence supporting a functional role for various multidrug resistance efflux transporters of the ABC superfamily which mediate resistance to hydrophilic and lipophilic antifolates, (b) To describe and evaluate the recent data suggesting a role for these efflux transporters in regulation of cellular folate homeostasis under folate replete and deplete conditions. Furthermore, novel developments and future perspectives regarding the identification of novel antifolate target proteins and mechanisms of action, as well as rationally designed emerging drug combinations containing antifolates along with receptor tyrosine kinase inhibitors are being discussed.

Multidisciplinary Symposium on Head and Neck Cancer. 2 December 2005, Philadelphia, PA, USA

The Multidisciplinary Symposium on Head and Neck Cancer focused on the emerging data that underlie optimal treatment for head and neck cancers, with a particular focus on squamous cell carcinoma of the head and neck. In-depth discussions showcased the published Phase II and Phase III data on the treatment of locally advanced disease with both induction chemotherapy and concurrent chemoradiotherapy. Molecular targets of interest and relevance in this tumour type were identified, as were the agents which target these putative proteins or pathways of carcinogenesis. Preliminary results from trials incorporating molecularly-targeted agents have shown a promising role for these compounds in the management of both locally advanced and recurrent/metastatic squamous cell carcinoma of the head and neck. The Symposium brought a clear message. The management of squamous cell carcinoma of the head and neck has evolved considerably, and with the advent of newer chemotherapeutic agents and molecularly targeted therapies, this field will continue to expand over time.

A Retrospective Analysis of the Outcome of Patients with Recurrent and/or Metastatic Squamous Cell Carcinoma of the Head and Neck Refractory to a Platinum-based Chemotherapy

AIMS

Recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN) develops in around 72,000 people in Europe every year. Treatment options are limited, mainly consisting of platinum-based palliative chemotherapy, with median overall survival times of only 6-8 months. No standard second-line treatment after progression on platinum-based chemotherapy is available. Few data have reported the efficacy of these treatments and the outcome of the patients. In an effort to generate such data, this retrospective study analysed clinical records from 151 patients with SCCHN refractory to platinum-based chemotherapy treated between 1990 and 2000 at seven different centres around Europe.

MATERIALS AND METHODS

Most patients (45%) received only best supportive care (BSC), and had a median survival of 56 days. A total of 28.5% of the patients received second-line chemotherapies: 16.6% radiotherapy and 9.9% chemoradiotherapy.

RESULTS

No objective response was observed with the various second-line chemotherapies. The overall median survival was 103 days (95% confidence interval [CI]: 77-126 days) for the whole cohort. The overall objective response rate (ORR) to second-line treatment in this population was calculated to be 2.6%.

CONCLUSION

These results highlight the need for additional treatment options for this disease. Similar, if not superior, response rates have already been observed in initial clinical studies of novel, targeted anti-cancer agents.

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.

Results of a randomised phase II study comparing docetaxel with methotrexate in patients with recurrent head and neck cancer

We report the results of a randomised phase II trial of docetaxel tested as a single agent in patients with recurrent head and neck cancer using methotrexate as a control arm to validate the results. Eligibility criteria included: histologically-confirmed squamous cell carcinoma, measurable disease, adequate haematological, renal and hepatic functions, no prior chemotherapy for recurrent cancer, signed informed consent. 40 mg/m2 methotrexate was given as a short weekly bolus i.v. injection, and 40 mg/m2 docetaxel was administered as a one hour weekly infusion. A total of 57 patients were randomised based on a ratio of 2/1:37 and 20 patients received docetaxel and methotrexate, respectively. Patient characteristics included 49 males and 8 females; the median age was 59 years (range: 43-82 years). Twenty-eight patients had a local-regional relapse and 29 had distant metastasis, the median disease-free interval was 7.9 months (range: 0-165 months). For patients treated with docetaxel, the following grade 3-4 toxicities occurred: neutropenia (12.5%) with febrile neutropenia in one patient (1%), anaemia (19%) mucositis (9%) and ungueal toxicity (9%). In the methotrexate arm, the grade 3-4 toxicities were: anaemia (15%) and mucositis (5%). The response rate was significantly higher in the docetaxel arm with 27% (95% confidence interval (CI): 21.7-32.3%) of objective responses versus 15% (95% CI: 11.2-18.8%) in the methotrexate arm. Overall survival and time to progression were super-imposable between the docetaxel and methotrexate treatments. Docetaxel given as a weekly infusion has a high activity in patients with head and neck cancer. A phase III trial is needed to test if this translates into a survival benefit for docetaxel use.

Results of randomised phase II studies comparing S16020 with methotrexate in patients with recurrent head and neck cancer

BACKGROUND

The purpose of this study was to carry out two randomised phase II trials of S16020, a new olivacine derivative, tested as a single agent in patients with recurrent head and neck cancer, using methotrexate as the control arm to validate the results.

PATIENTS AND METHODS

S16020 at either 80 or 100 mg/m2 was administered as a 3-h infusion every 3 weeks. Methotrexate, 40 or 50 mg/m2, was given by bolus injection, weekly for a minimum of 6 weeks. In total, 36 patients were entered in the randomised studies (25 in an initial study, 11 in a confirmatory study) of whom 24 received S16020 and 12 received methotrexate.

RESULTS

A scheduled interim analysis showed one patient having a non-confirmed objective response with S16020 and three patients having a confirmed objective response with methotrexate. In the methotrexate group, there were no patients with severe non-haematological toxicity. With S16020, there was a high incidence of severe non-haematological toxicities, including asthenia, oedema of the face, oedema and pain at the tumour sites and erythematous rash; consequently, both studies were stopped.

CONCLUSIONS

Both studies were stopped due to the poor anticipated benefit/risk ratio for S16020, although time to progression and overall survival time were similar in both treatment arms.

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.