Molecular mechanisms underlying the synergistic interaction of erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, with the multitargeted antifolate pemetrexed in non-small-cell lung cancer cells

Icotinib antagonizes ABCG2-mediated multidrug resistance, but not the pemetrexed resistance mediated by thymidylate synthase and ABCG2

ABCG2 is a potential biomarker causing multidrug resistance (MDR) in Non-Small Cell Lung Cancer (NSCLC). We conducted this study to investigate whether Icotinib, a small-molecule inhibitor of EGFR tyrosine kinase, could interact with ABCG2 transporter in NSCLC. Our results showed that Icotinib reversed ABCG2-mediated MDR by antagonizing the drug efflux function of ABCG2. Icotinib stimulated the ATPase activity in a concentration-dependent manner and inhibited the photolabeling of ABCG2 with [125I]-Iodoarylazidoprazosin, demonstrating that it interacts at the drug-binding pocket. Homology modeling predicted the binding conformation of Icotinib at Asn629 centroid-based grid of ABCG2. However, Icotinib at reversal concentration did not affect the expression levels of AKT and ABCG2. Furthermore, a combination of Icotinib and topotecan exhibited significant synergistic anticancer activity against NCI-H460/MX20 tumor xenografts. However, the inhibition of transport activity of ABCG2 was insufficient to overcome pemetrexed resistance in NCI-H460/MX20 cells, which was due to the co-upregulated thymidylate synthase (TS) and ABCG2 expression. This is the first report to show that the up-regulation of TS in ABCG2-overexpressing cell line NCI-H460/MX20 may play a role of resistance to pemetrexate. Our findings suggested different possible strategies of overcoming the resistance of topotecan and pemetrexed in the NSCLC patients.

Molecular testing in lung cancer in the era of precision medicine

The clinical expectations how pathologists should submit lung cancer diagnosis have changed dramatically. Until mid 90-ties a clear separation between small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC) was mostly sufficient. With the invention of antiangiogenic treatment a differentiation between squamous and non-squamous NSCLC was requested. When epidermal growth factor receptor (EGFR) mutation was detected in patients with pulmonary adenocarcinomas and subsequent specific treatment with tyrosine kinase inhibitors (TKIs) was invented, sub-classification of NSCLC and molecular analysis of the tumor tissue for mutations was asked for. Pathologists no longer submit just a diagnosis, but instead are involved in a multidisciplinary team for lung cancer patient management. After EGFR several other driver genes such as echinoderm microtubule associated protein like 4-AL-Kinase 1 (EML4-ALK1), c-ros oncogene 1, receptor tyrosine kinase (ROS1), discoidin domain receptor tyrosine kinase 2 (DDR2), fibroblast growth factor receptor 1 (FGFR1) were discovered, and more to come. Due to new developments in bronchology (EUS, EBUS) the amount of tissue submitted for diagnosis and molecular analysis is decreasing, however, the genes to be analyzed are increasing. Many of these driver gene aberrations are inversions or translocations and thus require FISH analysis. Each of these analyses requires a certain amount of tumor cells or one to two tissue sections from an already limited amount of tissues or cells. In this respect new genetic test systems have been introduced such as next generation sequencing, which enables not only to detect multiple mutations in different genes, but also amplifications and fusion genes. As soon as these methods have been validated for routine molecular analysis this will enable the analysis of multiple genetic changes simultaneously. In this review we will focus on genetic aberrations in NSCLC, resistance to new target therapies, and also to methodological requirements for a meaningful evaluation of lung cancer tissue and cells.

Phase I Study of Lapatinib and Pemetrexed in the Second-Line Treatment of Advanced or Metastatic Non-Small-Cell Lung Cancer With Assessment of Circulating Cell Free Thymidylate Synthase RNA as a Potential Biomarker

INTRODUCTION

Lapatinib is a dual tyrosine kinase inhibitor that targets epidermal growth factor receptor and HER2. We report on a dose-escalation study of lapatinib combined with pemetrexed in second-line treatment to evaluate the safety and efficacy in advanced or metastatic non-small-cell lung cancer (NSCLC) and an exploratory study in which circulating cell-free thymidylate synthase ribonucleic acid (cfTSmRNA) was measured in all patients and compared with clinical benefit.

PATIENTS AND METHODS

Eligible patients had stage IIIB or IV NSCLC after 1 previous line of chemotherapy and an Eastern Cooperative Oncology Group performance status of 0 to 2. Three dose levels (DLs) of lapatinib (daily)/pemetrexed (every 21 days) were evaluated: DL0, 1250 mg/400 mg; DL1, 1250 mg/500 mg; and DL2, 1500 mg/500 mg, respectively. The primary outcome was identification of the optimal treatment regimen.

RESULTS

Eighteen patients were treated (DL0: n = 4; DL1: n = 8; DL2: n = 6). The most common adverse events (any grade) were diarrhea (61%), rash (44%), nausea (33%), anemia, and fatigue (both 28%). DL1 was determined as optimal after 3 dose-limiting toxicities (DLTs) during the first cycle of DL2 (Grade 3 diarrhea and mucositis, Grade 4 lymphocytopenia); no other DLTs were observed. Partial response was detected in 4 patients. cfTSmRNA was at the limit of detection and was not measurable in all patients. Nonsignificant trends were observed, suggesting that higher levels of cfTSmRNA are associated with poorer outcome. Confirmatory studies are required.

CONCLUSION

Lapatinib and pemetrexed was well tolerated, and data suggest a similar response rate to pemetrexed monotherapy.

Erlotinib plus capecitabine as first-line treatment for older Chinese patients with advanced adenocarcinoma of the lung (C-TONG0807): an open-label, single arm, multicenter phase II study

Preclinical studies have shown synergism between epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors and antifolates in solid tumors. This study is to investigate the efficacy and tolerability of erlotinib plus capecitabine as first-line treatment in older Chinese patients (≥ 65 years) with lung adenocarcinoma. This is an open-label, single arm, multicenter phase II clinical trial. Sixty- two patients with previously untreated stage IIIB/IV adenocarcinoma and age 65 years or above were enrolled at four tertiary teaching hospitals and 2 provincial hospitals in China; 58 patients fulfilled the study requirements. Erlotinib (150 mg/day) and capecitabine (1000 mg/m2 twice daily on days 1-14) were administered during every 21-day cycle. The primary endpoint was the non-progression rate at 12 weeks. EGFR and K-ras mutation rates were determined using PCR. Tumor expression of different biomarkers was assessed using immunohistochemistry. In a cohort of 58 patients, 34 patients had no disease progression at 12 weeks following treatment. The objective response rate was 29.3%, and the disease control rate was 75.9%. The objective response rate was significantly higher in patients with EGFR mutations than in those with wild-type EGFR. Patients with thymidine phosphorylase-negative tumors had significantly longer overall survival after one year than patients with thymidine phosphorylase-positive tumors. Forty-four patients had at least one primary adverse events (AEs), including skin rash (n = 30), grade 3 AEs (n = 17), and grade 4 AEs (n = 7). This is the first phase II clinical trial to assess erlotinib plus capecitabine combination therapy as first-line treatment in older patients with lung adenocarcinoma. Erlotinib/capecitabine chemotherapy was significantly better in patients with EGFR mutations and in those with thymidine phosphorylase-negative tumors. The use of fluorouracil derivatives for the treatment of lung adenocarcinoma warrants further study.

Sequence-dependent antiproliferative effects of gefitinib and docetaxel on non-small cell lung cancer (NSCLC) cells and the possible mechanism

Purpose

Recent clinical trials showed that the sequential combination of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and chemotherapy could prolong the PFS and/or OS of advanced non-small cell lung cancer (NSCLC) patients with EGFR mutation. The aim of present study was to assess the optimal combination sequence and to explore its possible mechanism.

Methods

PC-9 cells and A549 cells, the lung adenocarcinoma cells with mutant and wide-type EGFR respectively, were treated with docetaxel/gefitinib alone or in different combination schedules. The EGFR and K-ras gene status was determined by qPCR-HRM technique. Cell proliferation was detected by MTT assay. The expression and phosphorylation of EGFR, ERK, Akt and IGF-1R were detected by western blot. Cell cycle distribution was observed by flow cytometry.

Results

Only sequential administration of docetaxel followed by gefitinib (D→G) induced significant synergistic effect in both cell lines (Combination Index<0.9). The reverse sequence (G→D) resulted in an antagonistic interaction in both cell lines (CI>1.1), whereas the concurrent administration (D+G) showed additive (0.9<CI<1.1)-synergistic effect in PC-9 cells and antagonistic-additive effect in A549 cells. Mechanism studies showed that docetaxel-induced phosphorylation of EGFR and ERK was repressed by subsequently used gefitinib, but not by concurrent exposure of gefitinib. The gefitinib-repressed phosphorylation of EGFR and ERK was reversed neither by concurrent nor by subsequent administration of docetaxel. D+G reinforced their inhibition on the phosphorylation of IGF-1R in PC-9 cells.

Conclusions

The cytotoxic drugs followed by EGFR-TKIs may be the optimal combination for antiproliferative effects in EGFR-mutant NSCLC cells, and the phosphorylation of EGFR and ERK might contribute to this effect.

A phase I, dose-escalation trial of continuous- and pulsed-dose afatinib combined with pemetrexed in patients with advanced solid tumors

INTRODUCTION

Afatinib, an irreversible ErbB family blocker, demonstrated synergistic inhibition of epidermal growth factor receptor-mutant cell growth with pemetrexed. This phase I study investigated the maximum tolerated dose (MTD), safety, pharmacokinetics, and antitumor activity of afatinib plus pemetrexed in patients with advanced solid tumors.

METHODS

In a 3 + 3 dose-escalation design, patients were given intravenous pemetrexed (500 mg/m(2)) on day 1 of a 21-day cycle (maximum 6 cycles), combined with continuous daily oral afatinib (schedule A [SA]; starting dose 30 mg, escalation to 50 mg) or pulsed-dose daily oral afatinib (schedule B [SB]; starting dose 50 mg, escalation to 70 mg) on days 1-6 of each 21-day cycle. Primary endpoint was determination of MTD based on dose-limiting toxicities (DLTs) in cycle 1.

RESULTS

Fifty-three patients were treated (SA: n = 23; SB: n = 30). Eight patients had DLTs in SA, 11 patients in SB; diarrhea and fatigue were the most common. MTD of afatinib was 30 mg in SA and 50 mg in SB. Six patients in SA and eight in SB completed 6 treatment cycles. One patient in each schedule had confirmed objective response; 18/53 patients had disease control (SA: n = 7; SB: n = 11). Most frequent drug-related adverse events were diarrhea, rash, fatigue, and stomatitis. No relevant pharmacokinetic interactions were observed.

CONCLUSIONS

Continuous- or pulsed-dose afatinib combined with pemetrexed exhibited a manageable safety profile. Pulsed dosing conferred no apparent safety or dose advantage. Continuous-dose afatinib 30 mg/day with pemetrexed is recommended for phase II studies.

Role of the pulmonologist in ordering post-procedure molecular markers in non-small-cell lung cancer: implications for personalized medicine

In the growing era of personalized medicine for the treatment of non-small-cell lung cancer (NSCLC), it is becoming increasingly important that sufficient quality and quantity of tumor tissue are available for morphologic diagnosis and molecular analysis. As new treatment options emerge that might require more frequent and possibly higher volume biopsies, the role of the pulmonologist will expand, and it will be important for pulmonologists to work within a multidisciplinary team to provide optimal therapeutic management for patients with NSCLC. In this review, we discuss the rationale for individualized treatment decisions for patients with NSCLC, molecular pathways and specific molecular predictors relevant to personalized NSCLC therapy, assay technologies for molecular marker analysis, and specifics regarding tumor specimen selection, acquisition, and handling. Moreover, we briefly address issues regarding racial and socioeconomic disparities as they relate to molecular testing and treatment decisions, and cost considerations for molecular testing and targeted therapies in NSCLC. We also propose a model for an institution-based multidisciplinary team, including oncologists, pathologists, pulmonologists, interventional radiologists, and thoracic surgeons, to ensure adequate material is available for cytological and histological studies and to standardize methods of tumor specimen handling and processing in an effort to provide beneficial, individualized therapy for patients with NSCLC.

Schedule-dependent synergistic interaction between docetaxel and gefitinib in NSCLC cell lines regardless of the mutation status of EGFR and KRAS and its molecular mechanisms

BACKGROUND

Tyrosine-kinase inhibitors (TKIs) and chemotherapy had different pharmacological mechanisms and therefore combined administration of TKIs and chemotherapy agents may have synergy. Our research aimed at exploring the cytotoxic interactions between gefitinib and docetaxel with different concentrations for non-small-cell lung cancer cell lines, and furthermore, the mechanisms underlying the cytotoxic synergism.

METHODS

NCI-H1650 [epidermal growth factor receptor (EGFR) mutation and KRAS wild-type], NCI-H292 (EGFR wild-type and KRAS wild-type) and A549 (EGFR wild-type and KRAS mutation) cell lines were treated with docetaxel and/or gefitinib. Cytotoxic interactions, cell cycle distribution and cell signal pathway were analyzed, respectively.

RESULTS

Cytotoxic interactions between docetaxel and gefitinib were dose-dependent and sequence-dependent in all these three cell lines. Docetaxel followed by gefitinib treatment was optimum regimen regardless of the mutation status of EGFR and KRAS. KRAS mutation and EGFR wild-type predicted insensitive to gefitinib and docetaxel combined treatment as well as gefitinib alone. G1 arrest was inconsistently associated with combination index (CI). However, apoptosis induction was schedule-dependent and can explain the synergism completely. Mitogen-activated protein kinase (MAPK) phosphorylation ratio was also schedule-dependent and positively correlated with CI.

CONCLUSION

Cytotoxic interactions between docetaxel and gefitinib were sequence-dependent regardless of the mutation status of EGFR and KRAS. Cell characteristic, apoptosis induction and MAPK phosphorylation but not cell cycle change may explain the molecular mechanisms of synergism.

Effects of pemetrexed, gefitinib, and their combination on human colorectal cancer cells

PURPOSE

The study investigated the effects of pemetrexed, gefitinib, and their combination on human colorectal cancer cells.

METHODS

Six human colorectal cancer cells were exposed to pemetrexed, gefitinib, and their combination. Antitumor effects were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Thymidylate synthase (TS) mRNA expression and EGFR mutation were studied by real-time RT-PCR and DNA sequence determination. Pharmacological interaction was studied using the combination index method. Cell cycle distribution and apoptosis were determined by flow cytometry. Activity assay was performed to assess the effects of drugs on TS activity, and Western blot was performed to assess the protein expression of pEGFR, pAKT, and pERK 1/2.

RESULTS

Six colorectal cancer cells are all sensitive to pemetrexed, and TS gene expression of cells was negatively related to pemetrexed sensitivity. The cytotoxic synergism was observed in concurrent pemetrexed combined with gefitinib and sequential pemetrexed followed by gefitinib. The combination of pemetrexed and gefitinib modulated cell cycle and induced apoptosis. Pemetrexed combined with gefitinib decreased TS mRNA expression and in situ activity. Pemetrexed induced an EGFR-mediated activation of the phosphatidylinositol 3-kinase/AKT and ERK pathway, which was inhibited by gefitinib.

CONCLUSIONS

Pemetrexed is a promising agent, and pemetrexed combined with gefitinib has a significantly synergistic effect on colorectal cancer cells, which seems to present a strategy of pemetrexed combined with EGFR-TKIs in colorectal cancer treatment.

Thymidylate synthase polymorphisms in genomic DNA as clinical outcome predictors in a European population of advanced non-small cell lung cancer patients receiving pemetrexed

Background

We studied whether thymidylate synthase (TS) genotype has an independent prognostic/predictive impact on a European population of advanced non-small cell lung cancer (NSCLC) patients receiving pemetrexed.

Methods

Twenty-five patients treated with pemetrexed-based regimens were included. Genomic DNA was isolated prior to treatment. The variable number of tandem repeat (VNTR) polymorphisms, the G > C single nucleotide polymorphisms (SNP) and the TS 6-bp insertion/deletion (6/6) in the 3′ untranslated region (UTR) polymorphisms were analyzed and correlated with overall response rate (ORR), progression-free survival (PFS), overall-survival (OS) and toxicity.

Results

The genotype +6/+6 predicted a higher ORR among active/former smokers compared to +6/-6 genotype (100% vs. 50%; p = 0.085). Overall, the 3R/3R genotype predicted a higher ORR (100%) over the rest VNTR polymorphisms (p = 0.055). The presence of 3R/3R genotype significantly correlated with a superior ORR in patients without EGFR activating mutations (100%) compared to 2R/2R, 2R/3R and 3R/4R genotype (77.8%, 33.3% and 0% respectively; p = 0.017). After a median follow-up of 21 months, a trend towards a better PFS, although not significant, was found among subjects showing 3R/3R polymorphisms (p = 0.089). A significantly superior OS was found in patients showing 3R/3R genotype rather than other VNTR polymorphisms (p = 0.019). No significant correlation with the toxicity was observed.

Conclusion

In our series, 3R/3R polymorphism correlated with a superior OS. Also, this polymorphism, when associated to wild type EGFR, was related to a higher ORR to pemetrexed. Toxicity was not significantly correlated with a specific TS genotype.

A randomised phase II study of pemetrexed versus pemetrexed+erlotinib as second-line treatment for locally advanced or metastatic non-squamous non-small cell lung cancer

INTRODUCTION

Pemetrexed and erlotinib have been approved as second-line monotherapy for locally advanced or metastatic non-small cell lung cancer (NSCLC). This multicentre, randomised, open-label, parallel phase II study assessed efficacy and safety of pemetrexed versus pemetrexed+erlotinib in patients with advanced non-squamous NSCLC.

METHODS

NSCLC stage III-IV patients who failed one prior platinum-based chemotherapy regimen, ≥ 1 measurable lesion by Response Evaluation Criteria in Solid Tumors, and Eastern Cooperative Oncology Group performance status ≤ 2 were eligible. Patients received pemetrexed 500 mg/m(2) with vitamin B12 and folic acid q3w alone or combined with erlotinib 150 mg daily. The primary end-point was progression-free survival (PFS). Secondary end-points were overall survival (OS), time-to-treatment failure (TTTF), response and toxicity.

RESULTS

Of 165 randomised non-squamous patients, 159 were treated (pemetrexed: 83; pemetrexed+erlotinib: 76). The median PFS (months; 95% CI) was 2.89 (1.94, 3.38) for pemetrexed versus 3.19 (2.86, 4.70) for pemetrexed+erlotinib (hazard ratio [HR] 0.63; 95% CI: (0.44, 0.90); P = 0.0047). The median OS (months; 95% CI) was 7.75 (5.29, 10.41) for pemetrexed versus 11.83 (8.18, 16.66) for pemetrexed+erlotinib (HR: 0.68; 95% CI: 0.46, 0.98; P = 0.019). The median TTTF (months: 95% CI) was 2.4 (1.74, 2.99) for pemetrexed versus 3.0 (2.23, 4.07) for pemetrexed+erlotinib (HR 0.64; 95% CI: 0.46, 0.89; P = 0.0034). One patient died in pemetrexed+erlotinib arm due to febrile neutropenia. Grades 3/4 drug-related toxicities (in ≥ 5% of patients) in pemetrexed/pemetrexed+erlotinib were febrile neutropenia (2.4%/10.5%), diarrhoea (1.2%/5.3%), rash (1.2%/9.2%); anaemia (6%/11.8%), leukopenia (9.6%/23.7%), neutropenia (9.6%/25.0%), and thrombocytopenia (4.8%/14.5%).

CONCLUSIONS

Pemetrexed+erlotinib treatment significantly improved PFS, OS and TTTF in 2nd line non-squamous NSCLC and was associated with an increase in grade 3/4 toxicities compared with pemetrexed alone.

Erlotinib with pemetrexed/cisplatin for patients with EGFR wild-type lung adenocarcinoma with brain metastases

Erlotinib and pemetrexed have been approved for the second-line treatment of non-small cell lung cancer. Recent reports indicated that erlotinib and pemetrexed exerted synergistic effects against lung adenocarcinoma. The available treatment options for lung cancer with brain metastases (BM) are currently limited. In the present study, we investigated the efficacy of the combined administration of erlotinib and pemetrexed in 9 patients with epidermal growth factor receptor (EGFR) wild-type lung adenocarcinoma with BM. Pemetrexed (500 mg/m²) and cisplatin (20 mg/m²) were administered on day 1 and days 1-3, respectively. Erlotinib (150 mg) was administered daily on days 4-20. The 9 patients harbored EGFR wild-type mutation in the primary tumor tissues. With regard to the BM, no patients achieved complete remission, 7 patients exhibited a partial response (PR), 1 had stable disease (SD) and 1 had progressive disease (PD). As regards the extracranial tumors, 3 patients exhibited a PR, 2 had SD, 3 had PD and 1 was not applicable. The performance status and the symptoms improved in 3 patients following treatment. The median progression-free survival for intracranial and extracranial disease control was 179 and 146.5 days, respectively. The median overall survival was 197.4 days. Therefore, erlotinib combined with pemetrexed/cisplatin, was found to be effective in the treatment of patients with EGFR wild-type lung adenocarcinoma.

Synergistic interaction of novel lactate dehydrogenase inhibitors with gemcitabine against pancreatic cancer cells in hypoxia

BACKGROUND

Hypoxia is a driving force in pancreatic-ductal-adenocarcinoma (PDAC) growth, metastasis and chemoresistance. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis, ensuring supply of energy and anabolites in hypoxic-environments. Therefore, we investigated the molecular mechanisms underlying the pharmacological interaction of novel LDH-A inhibitors in combination with gemcitabine in PDAC cells.

METHODS

Lactate dehydrogenase A levels were studied by quantitative RT-PCR, western blot, immunofluorescence and activity assays in 14 PDAC cells, including primary-cell-cultures and spheroids, in normoxic and hypoxic conditions. Cell proliferation, migration and key determinants of drug activity were evaluated by sulforhodamine-B-assay, wound-healing assay, PCR and LC-MS/MS.

RESULTS

Lactate dehydrogenase A was significantly increased under hypoxic conditions (1% O2), where the novel LDH-A inhibitors proved to be particularly effective (e.g., with IC50 values of 0.9 vs 16.3 μM for NHI-1 in LPC006 in hypoxia vs normoxia, respectively). These compounds induced apoptosis, affected invasiveness and spheroid-growth, reducing expression of metalloproteinases and cancer-stem-like-cells markers (CD133+). Their synergistic interaction with gemcitabine, with combination index values <0.4 in hypoxia, might also be attributed to modulation of gemcitabine metabolism, overcoming the reduced synthesis of phosphorylated metabolites.

CONCLUSION

Lactate dehydrogenase A is a viable target in PDAC, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours.

Post-progression survival in patients with non-small cell lung cancer with clinically acquired resistance to gefitinib

Most patients with tyrosine kinase inhibitor (TKI)-sensitive non-small cell lung cancer (NSCLC) eventually develop acquired resistance to TKIs. Factors that affect TKI-sensitive patient survival after progression during TKI treatment remain unknown. We attempted to identify factors that affected post-progression survival. We retrospectively reviewed 81 advanced NSCLC patients with disease progression following tumor response and durable (≥ 6 months) disease stabilization with first-line or second-line gefitinib. Post-progression survival (PPS) and characteristics were investigated and compared in patients who did (n = 16) and did not (n = 65) resume TKIs. Most patients were female never-smokers with adenocarcinoma. Median overall PPS was 10.3 months (95% confidence interval [CI], 7.458-13.142). Age, gender, smoking history, histology, Eastern Cooperative Oncology Group performance status at gefitinib initiation, initial stage, and platinum-based chemotherapy after gefitinib were not significant predictors of PPS. Pemetrexed use after gefitinib significantly improved PPS (18.5 vs 8.6 months; hazard ratio [HR], 0.45; P = 0.008). Gefitinib reuse tended to lengthen PPS but was insignificant in multivariate analysis (27.4 vs 8.8 months; HR, 0.53; P = 0.095). NSCLC patients assumed to have clinically acquired resistance to TKIs had relatively long PPS. TKIs reuse or pemetrexed use after progression with gefitinib may improve PPS.

Phase II study of pemetrexed and cisplatin plus cetuximab followed by pemetrexed and cetuximab maintenance therapy in patients with advanced nonsquamous non-small cell lung cancer

OBJECTIVES

The aim was to determine if combined pemetrexed, cisplatin, and cetuximab was efficacious and safe as first-line treatment in advanced nonsquamous non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

In this single-arm, multicenter clinical trial, patients with Stage IIIB/IV nonsquamous NSCLC received first-line therapy consisting of pemetrexed (500 mg/m(2)) and cisplatin (75 mg/m(2)) on Day 1 (21-day cycles) plus weekly cetuximab (400 mg/m(2) loading dose, then 250 mg/m(2)) for 4-6 cycles. Non-progressing patients received maintenance therapy consisting of pemetrexed and cetuximab as above until disease progression. All patients received vitamin supplementation, dexamethasone, and antihistamine prophylaxis. The primary endpoint was objective response rate (ORR). Secondary endpoints were progression-free survival (PFS), 1-year survival rate, translational research (TR) and safety.

RESULTS

Of the 113 patients receiving study drug, 109 were protocol-qualified. All patients completed ≥1 cycle of induction, and 51 (45%) and 49 (43%) patients completed ≥1 cycle of maintenance with pemetrexed and cetuximab, respectively. The ORR (n = 109) was 38.5% (80% confidence interval [CI], 32.3-45.1%), all partial responses. Median PFS was 5.8 (80% CI, 4.4-6.7) months. One-year survival rate was 45% (80% CI, 39-51%). In exploratory analyses, there was some preliminary evidence of potential prognostic relationships with efficacy outcomes for epidermal growth factor receptor and thyroid transcription factor-1 protein expression, but not for KRAS mutation or for thymidylate synthase or folate receptor-alpha protein expression. Seventy-three (64.6%) patients had study drug-related Grade 3/4 adverse events (AEs). Drug-related serious AEs were reported in 31 (27.4%) patients. There were 3 (2.7%) potentially drug-related deaths on-study or within 30 days of follow up.

CONCLUSION

Pemetrexed, cisplatin, and cetuximab appeared efficacious and tolerable in advanced nonsquamous NSCLC patients. The TR outcomes are hypothesis-generating given the study's size and nonrandomized nature.

A randomized phase II study comparing erlotinib versus erlotinib with alternating chemotherapy in relapsed non-small-cell lung cancer patients: the NVALT-10 study

BACKGROUND

Epidermal growth factor receptor tyrosine kinase inhibitors (TKIs) administered concurrently with chemotherapy did not improve outcome in non-small-cell lung cancer (NSCLC). However, in preclinical models and early phase noncomparative studies, pharmacodynamic separation of chemotherapy and TKIs did show a synergistic effect.

PATIENTS AND METHODS

A randomized phase II study was carried out in patients with advanced NSCLC who had progressed on or following first-line chemotherapy. Erlotinib 150 mg daily (monotherapy) or erlotinib 150 mg during 15 days intercalated with four 21-day cycles docetaxel for squamous (SQ) or pemetrexed for nonsquamous (NSQ) patients was administered (combination therapy). After completion of chemotherapy, erlotinib was continued daily. Primary end point was progression-free survival (PFS).

RESULTS

Two hundred and thirty-one patients were randomized, 115 in the monotherapy arm and 116 in the combination arm. The adjusted hazard ratio for PFS was 0.76 [95% confidence interval (CI) 0.58-1.02; P = 0.06], for overall survival (OS) 0.67 (95% CI 0.49-0.91; P = 0.01) favoring the combination arm. This improvement was primarily observed in NSQ subgroup. Common Toxicity Criteria grade 3+ toxic effect occurred in 20% versus 56%, rash in 7% versus 15% and febrile neutropenia in 0% versus 6% in monotherapy and combination therapy, respectively.

CONCLUSIONS

PFS was not significantly different between the arms. OS was significantly improved in the combination arm, an effect restricted to NSQ histology.

STUDY REGISTRATION NUMBER

NCT00835471.

Phase II study of pemetrexed plus intermittent erlotinib combination therapy for pretreated advanced non-squamous non-small cell lung cancer with documentation of epidermal growth factor receptor mutation status

INTRODUCTION

Erlotinib and pemetrexed have been approved for the second-line and maintenance treatment of non-small cell lung cancer (NSCLC). With the recommended doses determined by our previous phase I study, we conducted a phase II study to evaluate the efficacy and safety of combination of the two agents in pretreated non-squamous NSCLC patients.

METHODS

This study was performed in patients with stage IIIB/IV or post-surgically recurrent non-squamous NSCLC whose disease had progressed on or after receiving first-line chemotherapy. Patients received 500 mg/m(2) of intravenous pemetrexed every 21 days and 150 mg of oral erlotinib on days 2-16 until disease progression, unacceptable toxicity, or withdrawal of consent. The expected response rate and threshold were defined as 33.5% and 10%, respectively. Assuming a one-sided alpha of 5%, a power of 80%, the possible deviation from assessment, 26 patients were necessary.

RESULTS

A total of 27 patients, 16 males and 11 females were recruited. Patients had the median age of 70 years (range, 48-80 years) and included 21 stage IV diseases, 22 adenocarcinomas. Epidermal growth factor receptor (EGFR) mutations were examined in all patients. One patient had positive EGFR mutation, but the other 26 patients had wild-type EGFR. The median number of treatment courses was 3 (range, 1 to over 19). The best overall response rate and disease control rate were 11.1% and 63.0%, respectively. The median progression-free survival and overall survival were 2.8 months (95% confidence interval (CI); 1.9-7.5 months) and 15.8 months (95% CI; 9.3 months to not available), respectively. Dermal, hepatic, gastrointestinal and hematological disorders were the frequently observed adverse events. One patient experienced grade 3 drug-induced interstitial lung disease.

CONCLUSIONS

We could not demonstrate the add-on effect of intermittent erlotinib on pemetrexed in a second-line setting for patients with non-squamous NSCLC without EGFR mutations.

Synergistic effect of afatinib with su11274 in non-small cell lung cancer cells resistant to gefitinib or erlotinib

Epidermal growth factor receptor (EGFR) and c-MET receptors are expressed on many non-small cell lung cancer (NSCLC) cells. Current single agent therapeutic targeting of a mutant EGFR has a high efficacy in the clinic, but is not curative. Here, we investigated the combination of targeting EGFR and c-MET pathways in NSCLC cells resistant to receptor tyrosine kinase inhibitors (TKIs), using RNA interference and inhibition by TKIs. Different NSCLC cell lines with various genomic characteristics (H358, H1650 and H1975) were transfected with EGFR-specific-siRNA, T790M-specific-siRNA, c-MET siRNA or the combination. Subsequently EGFR TKIs (gefitinib, erlotinib or afatinib) or monoclonal antibody cetuximab were combined respectively with the c-MET-specific TKI su11274 in NSCLC cell lines. The cell proliferation, viability, caspase-3/7 activity and apoptotic morphology were monitored by spectrophotometry, fluorimetry and fluorescence microscopy. The combined effect of EGFR TKIs, or cetuximab and su11274, was evaluated using a combination index. The results showed that the cell lines that were relatively resistant to EGFR TKIs, especially the H1975 cell line containing the resistance T790M mutation, were found to be more sensitive to EGFR-specific-siRNA. The combination of EGFR siRNA plus c-MET siRNA enhanced cell growth inhibition, apoptosis induction and inhibition of downstream signaling in EGFR TKI resistant H358, H1650 and H1975 cells, despite the absence of activity of the c-MET siRNA alone. EGFR TKIs or cetuximab plus su11274 were also consistently superior to either agent alone. The strongest biological effect was observed when afatinib, an irreversible pan-HER blocker was combined with su11274, which achieved a synergistic effect in the T790M mutant H1975 cells. In a conclusion, our findings offer preclinical proof of principle for combined inhibition as a promising treatment strategy for NSCLC, especially for patients in whom current EGFR-targeted treatments fail due to the presence of the T790M-EGFR-mutation or high c-MET expression.

EGFR-tyrosine kinase inhibitor treatment beyond progression in long-term Caucasian responders to erlotinib in advanced non-small cell lung cancer: a case-control study of overall survival

INTRODUCTION

Some patients with advanced NSCLC show prolonged disease stabilization on treatment with an EGFR-tyrosine kinase inhibitor (TKI) such as erlotinib. It is not clear how to treat patients who progress after prolonged response to erlotinib. We hypothesized that TKI therapy beyond progression with added chemotherapy, radiotherapy or best supportive care may improve survival.

PATIENTS AND METHODS

We retrospectively analyzed all NSCLC patients treated with erlotinib at our institutions since 2004who progressed after at least stable disease on erlotinib for at least 6 months. The first 16 patients did not receive further TKI treatment after progression (controls). The following 25 patients were treated with TKI beyond progression (TKI patients). Overall survival (OS) was analyzed for the whole population, a case-control analysis of pairs matched for gender, smoking status, and histology (n=28), and for patients with known EGFR mutation status (n=23).

RESULTS

Treatment with TKI and chemotherapy was well tolerated. TKI-patients had a significantly longer OS from progression on TKI (case-control: median 14.5 vs. 2.0 months, HR 0.154) and longer OS from diagnosis of lung cancer (case-control: median 54.5 vs. 28.3 months, HR 0.474). An activating EGFR mutation was detected in 13 of the 23 patient tested (57%). Both among patients with and without detection of an activating EGFR mutation, those treated with erlotinib beyond progression had a longer survival.

CONCLUSIONS

In our case-control analysis in long-term erlotinib responders, treatment with TKI beyond progression in addition to chemotherapy or radiotherapy was feasible and lead to prolonged overall survival.

Preclinical pharmacokinetic/pharmacodynamic models to predict schedule-dependent interaction between erlotinib and gemcitabine

PURPOSE

To investigate the pharmacological effects of different erlotinib (ER) and gemcitabine (GM) combination schedules by in vitro and in vivo experiments and PK/PD models in non-small cell lung cancer cells.

METHODS

H1299 cells were exposed to different ER combined with GM schedules. Cell growth inhibition was analyzed to evaluate these schedules. A preclinical in vivo study was then conducted to compare tumor suppression effects of different schedules in H1299 xenografts. PK/PD models were developed to quantify the anti-tumor interaction of ER and GM.

RESULTS

Synergism was observed when ER preceded GM, but other sequences showed antagonism. The optimal in vitro schedule, or interval schedule, was applied to the animal study, which showed greater anti-tumor effect than simultaneous group. PK/PD models implied that interaction of the two drugs was additive in simultaneous treatment but synergistic in interval schedule. The simulation results showed that interval schedule can delay tumor growth for a longer time, and demonstrated more evident anti-tumor effect compared with simultaneous group if the treatment duration was longer.

CONCLUSIONS

Interval schedule of the two drugs can achieve synergistic anti-tumor effect, and is superior to simultaneous treatment.

Combination chemotherapy with intermittent erlotinib and pemetrexed for pretreated patients with advanced non-small cell lung cancer: a phase I dose-finding study

BACKGROUND

Erlotinib and pemetrexed have been approved for the second-line treatment of non-small cell lung cancer (NSCLC). These two agents have different mechanisms of action. Combined treatment with erlotinib and pemetrexed could potentially augment the antitumor activity of either agent alone. In the present study, we investigated the safety profile of combined administration of the two agents in pretreated NSCLC patients.

METHODS

A phase I dose-finding study (Trial registration: UMIN000002900) was performed in patients with stage III/IV nonsquamous NSCLC whose disease had progressed on or after receiving first-line chemotherapy. Patients received 500 mg/m(2) of pemetrexed intravenously every 21 days and erlotinib (100 mg at Level 1 and 150 mg at Level 2) orally on days 2-16.

RESULTS

Twelve patients, nine males and three females, were recruited. Patient characteristics included a median age of 66 years (range, 48-78 years), stage IV disease (nine cases), adenocarcinoma (seven cases) and activating mutation-positives in the epidermal growth factor receptor gene (two cases). Treatment was well-tolerated, and the recommended dose of erlotinib was fixed at 150 mg. Dose-limiting toxicities were experienced in three patients and included: grade 3 elevation of serum alanine aminotransferase, repetitive grade 4 neutropenia that required reduction of the second dose of pemetrexed and grade 3 diarrhea. No patient experienced drug-induced interstitial lung disease. Three patients achieved a partial response and stable disease was maintained in five patients.

CONCLUSIONS

Combination chemotherapy of intermittent erlotinib with pemetrexed was well-tolerated, with promising efficacy against pretreated advanced nonsquamous NSCLC.

Pharmacogenetics of conventional chemotherapy in non-small-cell lung cancer: a changing landscape?

Pharmacogenetics might be used to select patients who may benefit from specific chemotherapy that best matches the individual and tumor genetic profile, thus allowing maximum activity and minimal toxicity. Even if most studies in non-small-cell lung cancer yielded contradictory results, several potential biomarkers for sensitivity/resistance to platinum compounds, gemcitabine, taxanes and pemetrexed have been proposed. However, these markers need to be validated within larger prospective randomized trials of customized chemotherapy in homogeneous populations. Other critical points include the optimization/standardization of technical procedures, and further studies to unravel the extremely complex regulation of gene function. From this perspective, the evaluation of key factors influencing genotype-phenotype relationships, such as miRNAs, and functional studies to clarify pharmacokinetic/pharmacodynamic interactions, are fundamental for the pharmacogenetic optimization of cancer chemotherapy. Finally, limitation of the traditional pharmacogenetic approach relying only on candidate genes suspected of affecting drug response is now being overcome by the use of novel genome-wide studies.

Pemetrexed plus platinum as the first-line treatment option for advanced non-small cell lung cancer: a meta-analysis of randomized controlled trials

To compare the efficacy and toxicities of pemetrexed plus platinum with other platinum regimens in patients with previously untreated advanced non-small cell lung cancer (NSCLC). Methods: A meta-analysis was performed using trials identified through PubMed, EMBASE, and Cochrane databases. Two investigators independently assessed the quality of the trials and extracted data. The outcomes included overall survival (OS), progression-free survival (PFS), response rate (RR), and different types of toxicity. Hazard ratios (HRs), odds ratios (ORs) and their 95% confidence intervals (CIs) were pooled using RevMan software. Results: Four trials involving 2,518 patients with previously untreated advanced NSCLC met the inclusion criteria. Pemetrexed plus platinum chemotherapy (PPC) improved survival compared with other platinum-based regimens (PBR) in patients with advanced NSCLC (HR = 0.91, 95% CI: 0.83–1.00, p = 0.04), especially in those with non-squamous histology (HR = 0.87, 95% CI: 0.77–0.98, p = 0.02). No statistically significant improvement in either PFS or RR was found in PPC group as compared with PBR group (HR = 1.03, 95% CI: 0.94–1.13, p = 0.57; OR = 1.15, 95% CI: 0.95–1.39, p = 0.15, respectively). Compared with PBR, PPC led to less grade 3–4 neutropenia and leukopenia but more grade 3–4 nausea. However, hematological toxicity analysis revealed significant heterogeneities. Conclusion: Our results suggest that PPC in the first-line setting leads to a significant survival advantage with acceptable toxicities for advanced NSCLC patients, especially those with non-squamous histology, as compared with other PRB. PPC could be considered as the first-line treatment option for advanced NSCLC patients, especially those with non-squamous histology.

[Effects of EGFR-TKIs on sequential pemetrexed for advanced pulmonary adenocarcinoma]

BACKGROUND AND OBJECTIVE

Pemetrexed and epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) were used in patients with EGFR mutation to determine their effects. This study analyzed the influence of EGFR-TKIs on pemetrexed by observing the clinical efficacy and toxicity of pemetrexed following responses to EGFR-TKIs.

METHODS

Pulmonary adenocarcinoma patients were divided into EGFR-TKIs and no-EGFR-TKI groups according to the targeted therapy. All patients received pemetrexed (500 mg/m2) as second (or higher)-line treatment. The Response Evaluation Criteria in Solid Tumors (version 1.0) were used to evaluate the response to pemetrexed. Adverse events were classified based on version 4.0 of the National Cancer Institute Common Toxicity Criteria.

RESULTS

There were 57 patients in the EGFR-TKIs group and 56 in the no-EGFR-TKIs group. The disease control rates (DCRs) were 77.2% and 67.9% (P=0.367). The progression free survival (PFS) periods were 5.95 and 3.55 months (P=0.535). The overall survival (OS) periods were 10.10 and 8.24 months (P=0.432). However, these values were not statistically significant. The common toxicities of pemetrexed were hematologic and gastrointestinal (grades I and II). Two patients in the EGFR-TKIs group discontinued pemetrexed because of severe toxicities, which were not observed in the no-EGFR-TKIs group. Both groups had one patient who reduced dosage because of myelosuppression (grade IV). There were five and nine patients in the EGFR-TKIs and no-EGFR-TKIs groups, respectively, who delayed therapy not because of severe toxicities but due to subjective factors.

CONCLUSION

The DCRs, PFS periods, and OS periods of the patients administered with pemetrexed following EGFR-TKIs were better than those of the EGFR-TKIs group, but the differences were not statistically significant. Therefore, sequential pemetrexed administration caused negligible toxicities and can be used in adenocarcinoma therapy following responses to EGFR-TKIs.

Synergistic interaction between the novel histone deacetylase inhibitor ST2782 and the proteasome inhibitor bortezomib in platinum-sensitive and resistant ovarian carcinoma cells

The ability of histone deacetylase inhibitors to modulate the expression of genes relevant for growth or apoptotis regulation supports their interest in combination treatments of resistant tumors. We explored the effect of the combination of the histone deacetylase inhibitor ST2782 and the proteasome inhibitor bortezomib in ovarian carcinoma cell lines, including the IGROV-1 cell line and two p53 mutant platinum-resistant sublines (IGROV-1/OHP and IGROV-1/Pt1). We found a synergistic interaction between the two drugs, more evident in the p53-mutant resistant sublines, which was associated with increa sed apoptosis. The treatment with ST2782 resulted in early induction of Bax as well as in cleavage of caspase 3 and poly (ADP-ribose) polymerase only in the resistant cell lines. The inhibition of p53-transcriptional transactivation by pifithrin alpha in IGROV-1 cells enhanced the synergism. Conversely, knockdown of endogenous wild-type p53 in IGROV-1 cells determined synergism reduction. These opposite effects support the relevance of the transactivation-deficient mutant p53 as a synergism determinant. Moreover, in vivo studies indicated that tumor growth inhibition tended to be more evident in mice receiving the drug combination than in those treated with bortezomib alone. Overall, our study supports the potential effectiveness of the combination in platinum drug-resistant ovarian cancer carrying mutant p53.

Targeting the epidermal growth factor receptor in non-small cell lung cancer cells: the effect of combining RNA interference with tyrosine kinase inhibitors or cetuximab

BACKGROUND

The epidermal growth factor receptor (EGFR) is a validated therapeutic target in non-small cell lung cancer (NSCLC). However, current single agent receptor targeting does not achieve a maximal therapeutic effect, and some mutations confer resistance to current available agents. In the current study we have examined, in different NSCLC cell lines, the combined effect of RNA interference targeting the EGFR mRNA, and inactivation of EGFR signaling using different receptor tyrosine kinase inhibitors (TKIs) or a monoclonal antibody cetuximab.

METHODS

NSCLC cells (cell lines HCC827, H292, H358, H1650, and H1975) were transfected with EGFR siRNA and/or treated with the TKIs gefitinib, erlotinib, and afatinib, and/or with the monoclonal antibody cetuximab. The reduction of EGFR mRNA expression was measured by real-time quantitative RT-PCR. The down-regulation of EGFR protein expression was measured by western blot, and the proliferation, viability, caspase3/7 activity, and apoptotic morphology were monitored by spectrophotometry, fluorimetry, and fluorescence microscopy. The combined effect of EGFR siRNA and different drugs was evaluated using a combination index.

RESULTS

EGFR-specific siRNA strongly inhibited EGFR protein expression almost equally in all cell lines and inhibited cell growth and induced cell apoptosis in all NSCLC cell lines studied, albeit with a different magnitude. The effects on growth obtained with siRNA was strikingly different from the effects obtained with TKIs. The effects of siRNA probably correlate with the overall oncogenic significance of the receptor, which is only partly inhibited by the TKIs. The cells which showed weak response to TKIs, such as the H1975 cell line containing the T790M resistance mutation, were found to be responsive to siRNA knockdown of EGFR, as were cell lines with downstream TKI resistance mutations. The cell line HCC827, harboring an exon 19 deletion mutation, was more than 10-fold more sensitive to TKI proliferation inhibition and apoptosis induction than any of the other cell lines. Cetuximab alone had no relevant in vitro activity at concentrations obtainable in the clinic. The addition of EGFR siRNA to either TKIs or cetuximab additively enhanced growth inhibition and induction of apoptosis in all five cell lines, independent of the EGFR mutation status (wild-type or sensitizing mutation or resistant mutation). The strongest biological effect was observed when afatinib was combined with an EGFR-specific siRNA.

CONCLUSIONS

EGFR knockdown by siRNA further decreases the cell growth of lung cancer cells that are treated with TKIs or cetuximab alone, confirming that single agent drug targeting does not achieve a maximal biological effect. The siRNA inhibits EGFR oncogenic activity that bypasses downstream "resistance" mutations such as KRAS and PTEN. The combined treatment of siRNA and EGFR inhibitory agents is additive. The combination of a potent, irreversible kinase inhibitor such as afatinib, with EGFR-specific siRNAs should be further investigated as a new strategy in the treatment of lung cancer and other EGFR dependent cancers, including those with downstream resistance mutations.

[Sequence-dependent effect of docetaxel with gefitinib on the proliferation and apoptosis of lung adenocarcinoma cell H1975]

BACKGROUND AND OBJECTIVE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib show promising therapeutic effects in patients with advanced non-small cell lung cancer (NSCLC). However, despite an initial response to EGFR-TKIs treatment among responsive patients, most inevitably acquire resistance after a progression-free period of about 10 months. The percentage of T790M in TKI acquired-resistant patients in most studies is around 50%. The aim of this study is to assess the effects of the sequential administration of docetaxel and gefitinib on cell proliferation and apoptosis of lung adenocarcinoma cell H1975.

METHODS

An MTT assay was used to measure cell proliferation. The potency of the sequential administration of docetaxel and gefitinib were determined by isobolograms and combination index (CI). Cell apoptosis and cycle distribution were determined by flow cytometry. The Hoechst 33258 method was used to observe the apoptotic morphology. Chemical colorimetric luminescence was used to measure the caspase activity.

RESULTS

The isobolograms and CI showed that the sequential administration of docetaxel following gefitinib remarkably inhibits cell proliferation and cell apoptosis compared with other sequential administration models. The cycle distribution results indicate that sequential docetaxel administration following gefitinib blocked the cells in the G₂/M phase but not in the G0/G1. The activation of the Caspase-8/Caspase-3 cascade is mainly involved in the apoptotic pathway of lung adenocarcinoma cell H1975 in all sequential administration models.

CONCLUSIONS

The docetaxel administration following gefitinib might be a new stratagy for lung cancer with T790M mutation after having EGFR-TKIs resistance.

A study of electrochemical biosensor for analysis of three-dimensional (3D) cell culture

Cell culture has a fundamental role not only in regenerative medicine but also in biotechnology, pharmacology, impacting both drug discovery and manufacturing. Although cell culture has been generally developed for only two-dimensional (2D) culture systems, three-dimensional (3D) culture is being spotlighted as the means to mimic in vivo cellular conditions. In this study, a method for cytotoxicity assay using an electrochemical biosensor applying 3D cell culture is presented. In order to strengthen the advantage of a 3D cell culture, the experimental condition of gelation between several types of sol-gels (alginate, collagen, matrigel) and cancer cells can be optimized to make a 3D cell structure on the electrode, which will show the reproducibility of electrical measurement for long-term monitoring. Moreover, cytotoxicity test results applying this method showed IC(50) value of A549 lung cancer cells to erlotinib. Thus, this study evaluates the feasibility of application of the electrochemical biosensor for 3D cell culture to cytotoxicity assay for investigation of 3D cell response to drug compounds.

Combination therapy using oral S-1 and targeted agents against human tumor xenografts in nude mice

In this study, combination therapies using the oral fluoropyrimidine tegafur-gimeracil-oteracil (S-1) with several targeted agents or antibodies, were evaluated. First, the effects of tyrosine kinase inhibitors (erlotinib hydrochloride, sorafenib tosilate and sunitinib malate) against human non-small cell lung cancer (NSCLC), breast cancer and colorectal cancer were evaluated in vivo. The effects of the combination of S-1 and targeted antibodies (bevacizumab and cetuximab) against human colorectal cancers was also evaluated in vivo. S-1 and the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, erlotinib, showed a significant inhibition of growth in human NSCLC (Lu-99 and PC-9 cell lines). The antitumor activity of the combination of S-1 and erlotinib against Lu-99 and PC-9 cancer cell lines was significantly superior to either monotherapy (P<0.05). Combination therapy using the multi-tyrosine kinase inhibitors, sorafenib or sunitinib, with S-1 against breast cancer (MX-1 cell line) and NSCLC (NCI-H460 cell line) was significantly superior to either monotherapy (P<0.01). The combination of the anti-vascular endothelial growth factor antibody bevacizumab or the anti-EGFR antibody, cetuximab, with S-1 against human colorectal cancer [Col-1, KM20C (bevacizumab) and DLD-1 (cetuximab) cell lines] and a 5-fluorouracil (5-FU)-resistant cell line (KM12C/5-FU) was significantly superior to either monotherapy (p<0.01). In particular, the growth of the Col-1 cells was completely inhibited by the combination of S-1 and bevacizumab. No toxic mortalities and no significant difference in the body weight changes of the animals treated with S-1 combined with the targeted agents or with the mono-therapies were observed; therefore, the treatments appeared to be well-tolerated. Our preclinical findings indicate that the combination therapies of S-1 and targeted agents are promising treatment options.

The phosphoinositide 3-kinase inhibitor LY294002, decreases aminoacyl-tRNA synthetases, chaperones and glycolytic enzymes in human HT-29 colorectal cancer cells

The proposed anticancer drug LY294002, inhibits phosphoinositide-3 kinase (PI3K) that initiates a signalling pathway often activated in colorectal cancer (CRC). The effects of LY294002 (10 μM, 48 h) on the cytosolic, mitochondrial and nuclear proteomes of human HT-29 CRC cells have been determined using iTRAQ (isobaric tag for relative and absolute quantitation) and tandem mass spectrometry (MS/MS). Analysis of cells treated with LY294002 identified 26 differentially abundant proteins that indicate several mechanisms of action. The majority of protein changes were directly or indirectly associated with Myc and TNF-α, previously implicated in CRC progression. LY294002 decreased the levels of 6 aminoacyl-tRNA synthetases (average 0.39-fold) required for protein translation, 5 glycolytic enzymes (average 0.37-fold) required for ATP synthesis, and 3 chaperones required for protein folding. There was a 3.2-fold increase in lysozyme C involved in protein-glycoside hydrolysis. LY294002 increased cytosolic p53 with a concomitant decrease in nuclear p53, suggesting transfer of p53 to the cytosol where apoptosis might be initiated via the intrinsic mitochondrial pathway. Protein changes described here suggest that the anti-angiogenic effects of LY294002 may be related to p53; the mutational status of p53 in CRC may be an important determinant of the efficacy of PI3K inhibitors for treatment.

The development of a novel cancer immunotherapeutic platform using tumor-targeting mesenchymal stem cells and a protein vaccine

An ideal anticancer strategy should target only the malignant cells but spare the normal ones. In this regard, we established a platform, consisting of an antigen-delivering vehicle and a protein vaccine, for developing an immunotherapeutic approach with the potential for eliminating various cancer types. Mesenchymal stem cells (MSCs) have been demonstrated capable of targeting tumors and integrating into the stroma. Moreover, we have developed a protein vaccine PE(ΔIII)-E7-KDEL3 which specifically recognized E7 antigen and elicited immunity against cervical cancer. Taking advantage of tumor-homing property of MSCs and PE(ΔIII)-E7-KDEL3, we used E6/E7-immortalized human MSCs (KP-hMSCs) as an E7 antigen-delivering vehicle to test if this protein vaccine could effectively eliminate non-E7-expressing tumor cells. Animals which received combined treatment of KP-hMSCs and PE(ΔIII)-E7-KDEL3 demonstrated a significant inhibition of tumor growth and lung-metastasis when compared to PE(ΔIII)-E7-KDEL3 only and KP-hMSCs only groups. The efficiency of tumor suppression correlated positively to the specific immune response induced by PE(ΔIII)-E7-KDEL3. In addition, this combined treatment inhibited tumor growth via inducing apoptosis. Our findings indicated that KP-hMSCs could be used as a tumor-targeting device and mediate antitumor effect of PE(ΔIII)-E7-KDEL3. We believe this strategy could serve as a platform for developing a universal vaccine for different cancer types.

Preclinical emergence of vandetanib as a potent antitumour agent in mesothelioma: molecular mechanisms underlying its synergistic interaction with pemetrexed and carboplatin

BACKGROUND

Although pemetrexed, a potent thymidylate synthase (TS) inhibitor, enhances the cytoytoxic effect of platinum compounds against malignant pleural mesothelioma (MPM), novel combinations with effective targeted therapies are warranted. To this end, the current study evaluates new targeted agents and their pharmacological interaction with carboplatin-pemetrexed in human MPM cell lines.

METHODS

We treated H2052, H2452, H28 and MSTO-211H cells with carboplatin, pemetrexed and targeted compounds (gefitinib, erlotinib, sorafenib, vandetanib, enzastaurin and ZM447439) and evaluated the modulation of pivotal pathways in drug activity and cancer cell proliferation.

RESULTS

Vandetanib emerged as the compound with the most potent cytotoxic activity, which interacted synergistically with carboplatin and pemetrexed. Drug combinations blocked Akt phosphorylation and increased apoptosis. Vandetanib significantly downregulated epidermal growth factor receptor (EGFR)/Erk/Akt phosphorylation as well as E2F-1 mRNA and TS mRNA/protein levels. Moreover, pemetrexed decreased Akt phosphorylation and expression of DNA repair genes. Finally, most MPM samples displayed detectable levels of EGFR and TS, the variability of which could be used for patients' stratification in future trials with vandetanib-pemetrexed-carboplatin combination.

CONCLUSION

Vandetanib markedly enhances pemetrexed-carboplatin activity against human MPM cells. Induction of apoptosis, modulation of EGFR/Akt/Erk phosphorylation and expression of key determinants for pemetrexed and carboplatin activity contribute to this synergistic interaction, and, together with the expression of these determinants in MPM samples, warrant further clinical investigation.

Thymidylate synthase inhibitors for non-small cell lung cancer

INTRODUCTION

The folate-dependent enzyme thymidylate synthase (TS) plays a pivotal role in DNA replication/repair and cancer cell proliferation, and represents a valid target for the treatment of several tumor types, including NSCLC. NSCLC is the leading cause of cancer-related mortality, and several TS inhibitors have gone into preclinical and clinical testing, with pemetrexed emerging for its approval and widespread use as first-/second-line and maintenance therapy for this disease.

AREAS COVERED

This review summarizes the therapeutic options in NSCLC, as well as the background and rationale for targeting TS. The authors also review recent pharmacogenetic studies and data from clinical trials evaluating novel TS inhibitors, hoping that the reader will gain a comprehensive overview of the field of TS inhibition, specifically relating to drugs used or being developed for lung cancer patients.

EXPERT OPINION

TS is a validated target in NSCLC. However, benefits from conventional chemotherapy in NSCLC have plateaued, and more cost-effective results should be obtained with individualized treatment. Accordingly, the clinical success for TS inhibitors may depend on our ability to correctly administer these agents following biomarker-driven patient selection, including TS genotype and expression, and using the right combination therapy.

[Sequence-dependent effect of docetaxel with gefitinib on the proliferation and signal protein expression of human lung adenocarcinoma cell SPC-A1]

BACKGROUND AND OBJECTIVE

It has been proven that chemotherapy combined with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) could not increase response for advanced non-small cell lung cancer (NSCLC), but its cellular mechanism was not well known. The aim of this study is to assess the effects of sequential administration of docetaxel and gefitinib on the cell proliferation and signal pathway of lung adenocarcinoma cell SPC-A1 and its cellular mechanism.

METHODS

The mutation of EGFR and K-ras gene were examined by qPCR-HRM. MTT assay was used to measure the cell proliferation. The expression and phosphorylation of EGFR, ERK, AKT and IGF-1R were determined by Western blot.

RESULTS

No EGFR or K-ras gene mutation was found in SPC-A1 cells. Compared with docetaxel or gefitinib alone, no synergistic effects on the cell proliferation were observed in cells treated with docetaxel and gefitinib concomitantly or gefitinib followed by docetaxel. However, sequential administration of gefitinib following docetaxel could remarkably increase the inhibition of docetaxel on cell proliferation. Docetaxel increased, and gefitinib decreased, the phosphorylation of EGFR and ERK respectively. The suppression of pEGFR and pERK induced by gefitinib could not be activated by docetaxel, whether simultaneously or subsequently. No significant effects on the expression of AKT and p-AKT were found when docetaxel and gefitinib were administered simultaneously or sequentially. Docetaxel decreased the expression of IGF-1R.

CONCLUSION

The phosphorylation of both EGFR and ERK, not the phosphorylation of AKT or the expression of IGFR, may contribute to the synergistic effects of EFGR-TKI following chemotherapy on the cell proliferation of NSCLC.

Expression and pharmacological inhibition of thymidylate synthase and Src kinase in nonsmall cell lung cancer

The combination of cytotoxic chemotherapy with signaling pathway inhibitors represents a potential strategy to improve the treatment of nonsmall cell lung cancer (NSCLC). Thymidylate synthase (TS) is an enzyme essential for DNA synthesis, and its overexpression has been associated with the reduced sensitivity to antifolate agents. Src is a tyrosine kinase that modulates the cytotoxicity of cancer cells after drug treatment, and in vitro data indicate that its inhibition could revert the resistance to TS-inhibiting drugs. Our study investigated the significance of TS and Src expression in NSCLC tissues, and the effects of their pharmacological inhibition in cell lines. In tumor and normal tissues from 94 resected NSCLC patients, TS and Src transcript levels were found positively correlated (R(S) = 0.66), associated with patients smoking history and overall survival. At multivariate analysis, TS gene expression was an independent prognostic factor (relative risk (RR) = 1.78, from 1.16 to 2.72; p < 0.01). Immunohistochemical detection in tumor specimens confirmed that Src kinase activation, evaluated by phospho-specific antibody, was associated to a higher TS expression. In cell lines, dasatinib, a Src-inhibiting agent, synergistically enhanced pemetrexed-cytotoxicity of A549 cells, as evaluated by MTT and apoptosis assays. The biological explanation for this interaction was based on the upregulation of TS messenger RNA and protein levels induced by pemetrexed, which was significantly prevented by dasatinib cotreatment. The data of our study suggest that TS and Src may belong to a common pathway that bears prognostic significance in NSCLC, and that Src represents a potential target to improve the efficacy of TS-inhibiting agents.

Schedule-dependent cytotoxic synergism of pemetrexed and erlotinib in BXPC-3 and PANC-1 human pancreatic cancer cells

Previous studies have shown that both pemetrexed, a cytotoxic drug, and erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), inhibit the cell growth of pancreatic cancer cells. However, whether they exert a synergistic antitumor effect on pancreatic cancer cells remains unknown. The present study aimed to assess the synergistic effect of erlotinib in combination with pemetrexed using different sequential administration schedules on the proliferation of human pancreatic cancer BXPC-3 and PANC-1 cells and to probe its cellular mechanism. The EGFR and K-ras gene mutation status was examined by quantitative PCR high-resolution melting (qPCR-HRM) analysis. BXPC-3 and PANC-1 cells were incubated with pemetrexed and erlotinib using different administration schedules. MTT assay was used to determine cytotoxicity, and cell cycle distribution was determined by flow cytometry. The expression and phosphorylation of EGFR, HER3, AKT and MET were determined using Western blotting. Both pemetrexed and erlotinib inhibited the proliferation of BXPC-3 and PANC-1 cells in a dose- and time-dependent manner in vitro. Synergistic effects on cell proliferation were observed when pemetrexed was used in combination with erlotinib. The degree of the synergistic effects depended on the administration sequence, which was most obvious when erlotinib was sequentially administered at 24-h interval following pemetrexed. Cell cycle studies revealed that pemetrexed induced S arrest and erlotinib induced G(0)/G(1) arrest. The sequential administration of erlotinib following pemetrexed induced S arrest. Western blot analyses showed that pemetrexed increased and erlotinib decreased the phosphorylation of EGFR, HER3 and AKT, respectively. However, both pemetrexed and erlotinib exerted no significant effects on the phosphorylation of c-MET. The phosphorylation of EGFR, HER3 and AKT was significantly suppressed by scheduled incubation with pemetrexed followed by erlotinib, but not by concomitant or sequential incubation with erlotinib followed by pemetrexed. In summary, our results demonstrated that the combined use of erlotinib and pemetrexed exhibited a strong synergism in BXPC-3 and PANC-1 cells. The inhibitory effects were strongest after sequential administration of pemetrexed followed by erlotinib. The synergistic effects may be related to activation of the EGFR/HER3/AKT pathway induced by pemetrexed.

Thymidylate synthase and excision repair cross-complementing group-1 as predictors of responsiveness in mesothelioma patients treated with pemetrexed/carboplatin

PURPOSE

The pemetrexed/platinum agent combination represents the standard of care in first-line treatment for malignant pleural mesothelioma (MPM). However, there are no established indicators of responsiveness that can be used to optimize the treatment. This retrospective study aimed to assess the role of excision repair cross-complementing group-1 (ERCC1) and thymidylate synthase (TS) in tumors, and correlate expression levels and polymorphisms of these key determinants of drug activity with the outcome of MPM patients treated with carboplatin/pemetrexed in first-line setting.

EXPERIMENTAL DESIGN

Analysis of TS and ERCC1 polymorphisms, mRNA and protein expression was done by PCR and immunohistochemistry [with the H-score (histologic score)] in tumor specimens from 126 MPM patients, including 99 carboplatin-/pemetrexed-treated patients.

RESULTS

A significant correlation between low TS protein expression and disease control (DC) to carboplatin/pemetrexed therapy (P = 0.027), longer progression-free survival (PFS; P = 0.017), and longer overall survival (OS; P = 0.022) was found when patients were categorized according to median H-score. However, patients with the higher tertile of TS mRNA expression correlated with higher risk of developing progressive disease (P = 0.022), shorter PFS (P < 0.001), and shorter OS (P < 0.001). At multivariate analysis, the higher tertile of TS mRNA level and TS H-score confirmed their independent prognostic role for DC, PFS, and OS. No significant associations were found among ERCC1 protein expression, TS and ERCC1 polymorphisms, and clinical outcome.

CONCLUSIONS

In our series of carboplatin-/pemetrexed-treated MPM patients, low TS protein and mRNA levels were significantly associated to DC, improved PFS, and OS. Prospective trials for the validation of the prognostic/predictive role of TS in MPM patients treated with pemetrexed-based regimens are warranted.