Synergistic antitumor effect of S-1 and the epidermal growth factor receptor inhibitor gefitinib in non-small cell lung cancer cell lines: role of gefitinib-induced down-regulation of thymidylate synthase

Afatinib plus PEM and CBDCA overcome osimertinib resistance in EGFR-mutated NSCLC with high thrombospondin-1 expression

Osimertinib induces a marked response in non-small-cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) gene mutations. However, acquired resistance to osimertinib remains an inevitable problem. In this study, we aimed to investigate osimertinib-resistant mechanisms and evaluate the combination therapy of afatinib and chemotherapy. We established osimertinib-resistant cell lines (PC-9-OR and H1975-OR) from EGFR-mutant lung adenocarcinoma cell lines PC-9 and H1975 by high exposure and stepwise method. Combination therapy of afatinib plus carboplatin (CBDCA) and pemetrexed (PEM) was effective in both parental and osimertinib-resistant cells. We found that expression of thrombospondin-1 (TSP-1) was upregulated in resistant cells using cDNA microarray analysis. We demonstrated that TSP-1 increases the expression of matrix metalloproteinases through integrin signaling and promotes tumor invasion in both PC-9-OR and H1975-OR, and that epithelial-to-mesenchymal transition (EMT) was involved in H1975-OR. Afatinib plus CBDCA and PEM reversed TSP-1-induced invasion ability and EMT changes in resistant cells. In PC-9-OR xenograft mouse models (five female Balb/c-Nude mice in each group), combination therapy strongly inhibited tumor growth compared with afatinib monotherapy (5 mg/kg, orally, five times per week) or CBDCA (75 mg/kg, intraperitoneally, one time per week) + PEM (100 mg/kg, intraperitoneally, one time per week) over a 28-day period. These results suggest that the combination of afatinib plus CBDCA and PEM, which effectively suppresses TSP-1 expression, may be a promising option in EGFR-mutated NSCLC patients after the acquisition of osimertinib resistance.

Phase II study of S-1 and irinotecan combination therapy in EGFR-mutated non-small cell lung cancer resistant to epidermal growth factor receptor tyrosine kinase inhibitor: North Japan Lung Cancer Study Group Trial 0804 (NJLCG0804)

We conducted a multicenter phase II trial to evaluate the efficacy and safety of S-1 and irinotecan combination therapy in patients with epidermal growth factor receptor-mutated non-small-cell lung cancer treated with epidermal growth factor receptor tyrosine kinase inhibitors. Epidermal growth factor receptor-mutated non-small-cell lung cancer patients treated with epidermal growth factor receptor tyrosine kinase inhibitors and platinum-based chemotherapy received 80 mg/m² S-1 on days 1-14 and 70 mg/m² irinotecan on days 1 and 8 of a 21-day cycle. The primary endpoint was disease control rate 8 weeks after enrollment. The secondary endpoints were progression-free survival, overall response rate, and safety. We enrolled 25 patients from five hospitals. The patients underwent a median of four cycles. The disease control rate, 8 weeks after enrollment, was 84% (95% confidence interval 63.9-95.5%). Progression-free survival and overall survival were 5.0 and 17.1 months, respectively. The overall response rate was 52.0%. Grade ≥ 3 adverse events were reported in 56.0% of patients: hematological toxicities of leukopenia (44%), neutropenia (52%), anemia (20%), thrombocytopenia (20%), and febrile neutropenia (16%). Non-hematological toxicities of grade ≥ 3 included elevated alanine aminotransferase (4%), anorexia (8%), nausea (4%), diarrhea (16%), and pulmonary embolism (4%). None developed grade 5 toxicities. Combination therapy with S-1 and irinotecan in patients with epidermal growth factor receptor-mutated non-small-cell lung cancer treated with epidermal growth factor receptor tyrosine kinase inhibitors and platinum-based chemotherapy demonstrated high effectiveness with tolerable toxicities. Future phase III studies are needed to evaluate the role of this treatment in such patients.

Synergistic Antitumor Effects of Anlotinib Combined with Oral 5-Fluorouracil/S-1 via Inhibiting Src/AKT Signaling Pathway in Small-Cell Lung Cancer

Background

Small-molecule tyrosine inhibitor anlotinib which developed in China has been approved as a third-line treatment for patients with small-cell lung cancer (SCLC). Our previous clinical study found that anlotinib combined with S-1 has better short-term ORR than the single-agent anlotinib of SCLC and other small-molecule vascular targeted drug therapies in the treatment of SCLC. However, the molecular mechanism of those effect remains unclear.

Methods

SCLC cell line H446 was treated with either anlotinib, 5-FU alone, or combination. The cellular effects including cell viability, cell apoptosis, cell cycle, cell migration, and invasion were explored to evaluate the cell proliferation level. Western blot was performed to determine the protein levels of the combined action of the two drugs. The xenograft mouse model was established by injection of H446 cells into mouse, and the animals were randomized and assigned for the drug treatments. Body weights and tumor sizes were recorded. WB was conducted using tumor tissues. All data were collected and statistically analyzed using t-test to reveal the underlying molecular mechanism.

Results

When anlotinib was combined with 5-FU, the IC50 value of cells was significantly reduced. And apoptosis, cell cycle arrest, and cell motility rates were stronger when anlotinib combined with 5-FU than in the anlotinib or 5-FU alone. In H446 cell-derived xenograft mouse model, tumor volumes were significantly decreased in Anlo/5-FU combination group than anlotinib or 5-FU alone group. Western blot showed the decreasing expression of p-Src/p-AKT in the Anlo/5-FU group.

Conclusion

Our data revealed that the treatment of combination of antitumor angiogenesis agent anlotinib with chemotherapy drug 5-FU may have synergistic cytotoxicity to SCLC in vitro and in vivo. This treatment modality reduced cell proliferation and migration via Src/AKT pathway. This new strategy may be a promising treatment for SCLC but needs to be confirmed in future clinical trials.

Survival benefit of using pemetrexed for EGFR mutation-positive advanced non-small-cell lung cancer in a randomized phase III study comparing gefitinib to cisplatin plus docetaxel (WJTOG3405)

BACKGROUND

Pemetrexed is common cytotoxic chemotherapy among non-squamous non-small cell lung cancer (non-Sq-NSCLC) patients; however, among epidermal growth factor receptor (EGFR)-positive lung cancer, there is no clear evidence to support the efficacy of sequential treatment with pemetrexed.

MATERIAL AND METHODS

We performed a post-hoc analysis of subsequent chemotherapies among 144 patients who received the post-protocol treatment in the phase III trial WJTOG 3405 comparing gefitinib to cisplatin plus docetaxel, and analyzed the effect of pemetrexed on overall survival (OS).

RESULTS

Patients with treatment including pemetrexed exhibited significantly longer OS in comparison to those without pemetrexed; the median OS in the pemetrexed + and pemetrexed- patients were 40.7 months and 28.0 months, respectively (0.55 of HR [95% CI: 0.38-0.80, p = 0.0020]). On the other hand, other treatments, including docetaxel, TS-1 and paclitaxel showed no significant impact on OS. The multivariate analysis with a time-dependent Cox proportional hazards model showed that treatment including pemetrexed, as well as PS 0 and post-operative recurrence, were independent predictors of a good prognosis. Moreover, among patients who received at least four lines of prior treatment, pemetrexed + treatment also significantly prolonged OS in comparison to pemetrexed- treatment (median OS pemetrexed + vs. pemetrexed-: 44.4 months vs. 32.6 months; HR: 0.55 [95% CI: 0.31-0.94, p = 0.0290]).

CONCLUSIONS

Sequential treatment including pemetrexed against EGFR-mutated NSCLC might be associated with a better outcome. It was considered that pemetrexed should be administered without fail as a sequential treatment to improve the prognosis of EGFR-mutated NSCLC as well as like EGFR-tyrosine kinase inhibitors.

Hype or hope - Can combination therapies with third-generation EGFR-TKIs help overcome acquired resistance and improve outcomes in EGFR-mutant advanced/metastatic NSCLC?

Three generations of epidermal growth factor receptor - tyrosine kinase inhibitors (EGFR-TKIs) have been developed for treating advanced/metastatic non-small cell lung cancer (NSCLC) patients harboring EGFR-activating mutations, while a fourth generation is undergoing preclinical assessment. Although initially effective, acquired resistance to EGFR-TKIs usually arises within a year due to the emergence of clones harboring multiple resistance mechanisms. Therefore, the combination of EGFR-TKIs with other therapeutic agents has emerged as a potential strategy to overcome resistance and improve clinical outcomes. However, results obtained so far are ambiguous and ideal therapies for patients who experience disease progression during treatment with EGFR-TKIs remain elusive. This review provides an updated landscape of EGFR-TKIs, along with a description of the mechanisms causing resistance to these drugs. Moreover, it discusses the current knowledge, limitations, and future perspective regarding the use of EGFR-TKIs in combination with other anticancer agents, supporting the need for bench-to-bedside approaches in selected populations.

Concurrent chemotherapy and first-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) with or without an antiangiogenic agent as first-line treatment in advanced lung adenocarcinoma harboring an EGFR mutation

BACKGROUND

Previous studies have demonstrated the combination of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) and other antitumor agents may delay drug resistance. In this study, we retrospectively reviewed the efficacy and safety of first-line concurrent EGFR-TKIs and platinum-based doublet chemotherapy with or without an antiangiogenic agent for advanced lung adenocarcinoma patients in the real world.

METHODS

A total of 30 patients with advanced lung adenocarcinoma and activating EGFR mutations concurrently received an EGFR-TKI and platinum-based doublet chemotherapy with or without bevacizumab. The safety profile and efficacy were retrospectively reviewed.

RESULTS

At the median follow-up time of 22.1 months, 18 patients had experienced disease progression, and six patients had died because of disease. The median progression-free survival (mPFS) was 21.2 months (95% CI: 12.631-29.798). Of the 28 patients who had measurable lesions, the objective response rate and disease control rate were 71.4% and 96.4%, respectively (one patient achieved complete remission, 19 patients had a partial response and seven patients had stable disease). Male patients had significantly longer mPFS than female patients (32.6 vs. 14.6 months, HR = 3.593, 95% CI: 1.158-11.148, p = 0.027). The most frequently seen grade 3/4 adverse events were hematological toxicities, seen in three cases (10%). Three patients ceased bevacizumab due to vascular events, including hypertension (grade 2, 6.7%) and venous thrombosis (grade 2, 3.3%), and continued EGFR-TKI and platinum-based doublet chemotherapy.

CONCLUSIONS

The combination of first-generation EGFR-TKIs with platinum-based chemotherapy may be a first-line treatment for advanced lung adenocarcinoma patients harboring activated EGFR mutations and is well tolerated.

Efficacy and acquired resistance of EGFR-TKI combined with chemotherapy as first-line treatment for Chinese patients with advanced non-small cell lung cancer in a real-world setting

Background

To compare the benefits and explore the cause of acquired resistance of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) and its combination with chemotherapy in advanced non-small-cell lung cancer (NSCLC) patients harboring EGFR mutation in a real-life setting.

Methods

This retrospective analysis included 117 advanced NSCLC patients with EGFR mutation who underwent next-generation sequencing (NGS) prior to treatment. The combination group included 50 patients who received the regimen of EGFR-TKI combined with chemotherapy, while the EGFR-TKI monotherapy group included 67 patients treated with TKI only. The primary endpoint of this study was progression-free survival (PFS); the secondary endpoints were overall survival (OS), response rate, and toxicity.

Results

The median PFS was significantly longer in the combination group than in the EGFR-TKI monotherapy group (19.00 months [95% CI, 14.67–23.33] vs. 11.70 months [95% CI, 10.81–12.59], p < 0.001). Subgroup analysis showed a similar trend of results. The median OS was not reached in the combination group and was 38.50 (95% CI, 35.30–41.70) months in the EGFR-TKI monotherapy group (p = 0.586). Patients in the combination group were more likely to experience adverse events, most of which showed the severity of grade 1 or 2. T790M mutation remains the main reason for acquired resistance, and the frequency of T790M mutation was similar between the two groups (p = 0.898).

Conclusions

Compared with EGFR-TKI monotherapy, EGFR-TKI combined with chemotherapy significantly improved PFS in advanced NSCLC patients with EGFR mutation, with acceptable toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08291-9.

Outcomes of concurrent versus sequential icotinib therapy and chemotherapy in advanced non-small cell lung cancer with sensitive EGFR mutations

Abstract

To explore a better treatment strategy for patients with advanced non‐small cell lung cancer harboring sensitive epidermal growth factor receptor mutations, a total of 271 patients were retrospectively analyzed. The patients were divided into two groups: the combination group (58 cases), which received concurrent icotinib, pemetrexed, and platinum treatment, and the sequential group (213 cases), which received the sequential pemetrexed and platinum therapy, followed by icotinib treatment. The primary end points were progression‐free survival (PFS) and PFS on the subsequent line of therapy (PFS2). PFS in the combination group was significantly higher compared with that in the sequential group (16.89 months vs. 9.90 months; p < 0.001). PFS in the combination group was also significantly higher than PFS2 in the sequential group (16.89 months vs. 14.05 months; p = 0.009). The overall survival (OS) of the patients was 33.22 months (95% confidence interval (CI): 26.99–37.01) in the combination group and 26.47 months (95% CI: 25.05–26.95) in the sequential group (p < 0.001). The combination group’s objective response rate was superior to that of the sequential group (79.31% vs. 52.11%; p < 0.001). Propensity score matching also revealed that icotinib therapy combined with chemotherapy extended the PFS, PFS2, and OS of the patients (p < 0.0001, p = 0.003, and p = 0.001, respectively). The combination group’s objective response rate was also better compared with the sequential group (79.31% vs. 51.72%; p = 0.001). In conclusion, our study demonstrated icotinib combined with chemotherapy can improve survival efficacy better than the separated two‐line therapy.

Phase I/II study of erlotinib plus S-1 for patients with previously treated non-small cell lung cancer: Thoracic Oncology Research Group (TORG) 0808/0913

Introduction In preclinical data, the combination therapy with S-1 and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) had a synergistic antitumor effect on non-small cell lung cancer (NSCLC), regardless of the EGFR mutation status. Patients and Methods Patients with previously treated NSCLC and adequate organ function regardless of EGFR mutation status were eligible for the phase I study, with wild-type EGFR were eligible for the phase II study. Treatment consisted of erlotinib 150 mg/body orally once every day and S-1 60 mg/m², 70 mg/m², or 80 mg/m² (level 0, level 1, or level 2) orally on days 1-14 every three weeks. The primary endpoint for the phase I study was the determination of the recommended dose (RD), the phase II study was the overall response rate (ORR). Results A total of 7 patients with performance-status (PS) 0 or 1 were enrolled as subjects in phase I. Five of these subjects were EGFR-mutation positive. Four subjects were enrolled at S-1 dose level 1 and 3 were enrolled at S-1 dose level 2. No dose-limiting toxicities were observed in these subjects. The RD was decided as erlotinib 150 mg/body and S-1 80 mg/m². In phase I, 5 subjects achieved partial response, and the ORR was 71.4%. A total of 10 patients with PS 0, 1, or 2 EGFR-wild type NSCLC were enrolled in phase II. In phase II, the ORR was 10.0%, and the disease control rate (DCR) was 40.0%. After the enrollment of 10 subjects, enrollment was stopped based on two treatment-related deaths. Conclusion The combination therapy of erlotinib plus S-1 was not feasible in the EGFR wild-type NSCLC at least and early stopped. Trial registration: UMIN-CTR Identifier: 000003421 (2010/03/31, phase I), 000003422 (2010/03/31, Phase II).

First-iGAP: A Randomized Placebo-Controlled Phase II Study of First-line Intercalated Gefitinib and Pemetrexed-Cisplatin Chemotherapy for Never-Smoker Lung Adenocarcinoma Patients

BACKGROUND

We aimed to evaluate whether intercalated combination of EGFR tyrosine kinase inhibitor gefitinib and chemotherapy improves survival outcomes in never-smokers with advanced lung adenocarcinoma.

PATIENTS AND METHODS

Never-smokers with chemo-naive stage IIIB/IV lung adenocarcinoma were randomly assigned to receive either gefitinib or placebo on days 5 to 18 of a 3-weekly cycle of pemetrexed and cisplatin. Chemotherapy was given up to 9 cycles, after which gefitinib or placebo was given daily. Patients in the placebo arm who had progression were crossed over to receive gefitinib.

RESULTS

Between June 2012 and December 2014, 76 patients with median age of 58.0 years were randomized, 39 on gefitinib and 37 on the placebo arm. EGFR mutation was positive in 34 (44.7%) patients. Baseline characteristics were well balanced between the 2 arms. The gefitinib arm had a better response rate (79.5% vs. 51.4%, P = .010) and median progression-free survival (PFS) (12.4 vs. 6.7 months, hazard ratio [HR] 0.49, P = .005) than the placebo arm; however, there was no statistically significant difference in median overall survival between the 2 arms (31.8 vs. 22.9 months, HR 0.78, P = .412). The PFS benefit of intercalated use of gefitinib over placebo was more apparent for patients with EGFR-mutant tumors (13.3 vs. 7.8 months, P = .025) than those with EGFR-wild-type tumors (8.2 vs. 6.6 months, P = .063). Overall, there was no difference in the frequency of severe adverse effect between the 2 arms.

CONCLUSIONS

Intercalated combination of gefitinib with pemetrexed and cisplatin was well tolerated and improved PFS in never-smoker patients with lung adenocarcinoma.

Determining the appropriate treatment for different EGFR mutations in non-small cell lung cancer patients

Introduction: Epidermal growth factor receptor (EGFR) mutations occur in a significant fraction of non-small cell lung cancer (NSCLC) patients. Most common activating mutations are in-frame deletion in exon 19 and point mutation in exon 21. EGFR tyrosine kinase inhibitors (TKIs) represent standard of care of EGFR mutated patients bearing common mutations. Therapy for individuals carrying uncommon mutations, such as G719X, L861Q, S768I, is less defined and few options exist for individuals harboring EGFR exon 20 mutations. In all mutated patients, drug resistance remains the most critical clinical problem and new agents and strategies are under investigation.Areas covered: We have reviewed the current status of NSCLC EGFR mutated treatment by analyzing data from preclinical studies, clinical prospective and retrospective trials in order to analyze current and future options for patients harboring different EGFR mutations.Expert opinion: At the present time, available data demonstrated that osimertinib is the best EGFR-TKI for front-line therapy. Other agents, such as dacomitinib, and new drug combinations, such as regimens including anti-angiogenic agents or chemotherapy, demonstrated to significantly prolong progression-free survival or overall survival, representing potential alternative to osimertinib. Many questions remain opened, including best drug sequencing and needing of new therapeutic approaches extending patient survival and cure rate.

Synergistic and Pharmacotherapeutic Effects of Gemcitabine and Cisplatin Combined Administration on Biliary Tract Cancer Cell Lines

Gemcitabine (GEM) and cisplatin (CDDP) combination therapy (GC) is the standard chemotherapy for advanced biliary tract cancer (BTC); however, its pharmacotherapeutic efficacy remains unclear. To investigate the effects of GC, we selected 11 from 17 BTC cell lines, according to their GEM sensitivity, to be assessed using the MTS assay. The presence of synergistic effects of GC was determined using the Bliss additivism model (BM) and the combination index (CI) at a GEM:CDDP molar ratio of 7:1; this ratio was based on the respective human renal clearances of the two drugs. The pharmacotherapeutic effects were evaluated by comparing the IC50 values for administrations of GEM alone and GC in combination. All cell lines showed synergistic effects when analyzed using the BM. Based on the CI values, strong synergism, synergism, and additive effects were seen in four, five, and two cell lines, respectively. For all four GEM-resistant cell lines, on which GC had strong synergistic effects, the pharmacotherapeutic effects of GC were disappointing, with all IC50 values > 1 µM. For the GEM-effective cell lines, on which GC had synergistic or additive effects, the IC50 values were all <1 µM, and the differences were small between the IC50s for administration of GEM alone and GC in combination. Our results suggest that GC has synergistic effects on BTC cell lines but that its pharmacotherapeutic effects are inadequate.

Epidermal Growth Factor Receptor (EGFR)-Tyrosine Kinase Inhibitors (TKIs) Combined with Chemotherapy Delay Brain Metastasis in Patients with EGFR-Mutant Lung Adenocarcinoma

BACKGROUND

Whether epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) combined with chemotherapy can delay the occurrence of brain metastasis (BM) is unclear.

OBJECTIVE

This retrospective study aimed to evaluate whether EGFR-TKIs combined with chemotherapy can delay BM and decrease the incidence of BM as initial progression.

PATIENTS AND METHODS

The data of 100 patients with EGFR-mutant advanced lung adenocarcinoma were retrospectively reviewed. The patients had no BM at initial diagnosis, and BM occurred during the treatment. Patients received EGFR-TKI only or EGFR-TKI combined with chemotherapy. Intracranial progression-free survival (iPFS), systemic progression-free survival (PFS), and overall survival (OS) were evaluated.

RESULTS

The overall median OS was 39 months (95% confidence interval (CI), 35.6-42.4 months). The median OS of EGFR-TKI combined with chemotherapy and EGFR-TKI only are 41 months (95% CI 35.5-46.5 months) and 39 months (95% CI 36.8-41.2 months), respectively. Patients in the combination treatment group had longer PFS (16 vs. 10 months; P = 0.030) and iPFS (21 vs. 14 months; P = 0.026). Further, as initial progression, fewer patients developed BM in the combined treatment group compared with the EGFR-TKI-only group (30.6% vs. 52.9%, P = 0.002) with a hazard ratio of 0.64 (95% CI 0.43-0.96). After controlling for significant covariables in a multivariable model, the different treatment strategies were independently associated with improved iPFS.

CONCLUSIONS

In this retrospective analysis, EGFR-TKIs combined with chemotherapy could improve PFS. Further, the combined treatment could delay BM occurrence and decrease the incidence of BM as initial progression.

Combination TS-1 plus EGFR-tyrosine kinase inhibitors (TKIs) for the treatment of non-small cell lung cancer after progression on first-line or further EGFR-TKIs: A phase II, single-arm trial

Background

EGFR‐tyrosine kinase inhibitors (TKIs) combined with TS‐1 might overcome EGFR‐TKI resistance, which has been indicated by several preclinical studies. We investigated the synergistic efficacy and safety of the combination therapy of EGFR‐TKIs and TS‐1 in non‐small cell lung cancer (NSCLC) patients with acquired resistance to previous EGFR‐TKI therapy.

Methods

This was a phase II, single‐arm and single‐center prospective study. Stage IIIB–IV NSCLC patients with acquired resistance to prior EGFR‐TKI treatment were enrolled. All patients were administered combination therapy of TS‐1 and continuing EGFR‐TKIs in this study. The primary endpoints were progression‐free survival (PFS), while overall survival (OS), disease control rate (DCR), and safety were secondary endpoints.

Results

A total of 42 patients with acquired resistance to EGFR‐TKIs were eligible for this study. The median PFS for all patients was five months (95% confidence interval [CI] 3.6–5.4). The OS and DCR were 31.9 (95% CI 17.8–46.0) months and 69.0% (29/42), respectively. No grade 4 toxicity or grade 3 hematologic toxicity was observed in this study. One patient (2%) experienced grade 3 elevated total serum bilirubin.

Conclusion

The combination treatment of TS‐1 and EGFR‐TKIs was effective and well tolerated by patients who had experienced prior EGFR‐TKI treatment failure. Our results need to be validated by larger prospective clinical trials.

First-line therapy for advanced non-small cell lung cancer with activating EGFR mutation: is combined EGFR-TKIs and chemotherapy a better choice?

As the standard first-line treatment for advanced non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutation, EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have significantly improved the median progression-free survival (PFS) up to 18.9 months. However, almost all patients eventually develop acquired resistance to EGFR-TKIs, which limits the first-line PFS. To overcome the resistance and improve overall survival, researchers have tried to identify the resistance mechanisms and develop new treatment strategies, among which a combination of EGFR-TKIs and cytotoxic chemotherapy is one of the hotspots. The data from preclinical and clinical studies on combined EGFR-TKIs and chemotherapy have shown very interesting results. Here, we reviewed the available preclinical and clinical studies on first-line EGFR-TKIs-chemotherapy combination in patients with advanced NSCLC harboring activating EGFR mutation, aiming to provide evidences for more potential choices and shed light on clinical treatment.

Overcoming resistance to EGFR tyrosine kinase inhibitors in lung cancer, focusing on non-T790M mechanisms

INTRODUCTION

despite initial dramatic efficacy of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant lung cancer patients, emergence of acquired resistance is almost inevitable. The EGFR T790M secondary mutation that accounts for ~50% of resistance is now treatable with osimertinib. However, for the remaining 50% of patients who develop resistance mechanisms other than T790M mutation, cytotoxic chemotherapies are still the standard of care and novel treatment strategies are urgently needed. Areas covered: In this review, we discuss current experimental and clinical evidence to develop better treatment strategies to overcome or prevent acquired resistance to EGFR-TKIs in lung cancers, focusing on non-T790M mechanisms. Expert commentary: There are numerous non-T790M resistant mechanisms to EGFR-TKIs, and therefore, strategies that can be applied to many of these resistance mechanisms may be reasonable and useful in clinical practice. Although the combination of cytotoxic chemotherapy plus an EGFR-TKI has proved to be detrimental following front-line EGFR-TKI treatment failure, promising experimental and/or early clinical data have been reported for the combination of bevacizumab or anti-EGFR monoclonal antibody plus EGFR-TKIs. Upfront polytherapy, which co-targets potential resistance mechanisms or other important signaling for EGFR-mutant lung cancer cells, is also a promising strategy.

A Review of Regimens Combining Pemetrexed With an Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor in the Treatment of Advanced Nonsquamous Non-Small-Cell Lung Cancer

Pemetrexed is a standard first-line treatment for advanced nonsquamous non-small-cell lung cancer (NSCLC), and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are a standard first-line treatment for advanced nonsquamous NSCLC with activating EGFR mutations. Pemetrexed and EGFR TKIs have different mechanisms of action and minimally overlapping toxicity profiles; therefore, it is hypothesized that their combination might result in acceptable toxicity, provided that the synergistic antitumor activity observed in preclinical studies is achieved. This review summarizes clinical trials of pemetrexed in combination with an EGFR TKI for the treatment of advanced nonsquamous NSCLC in the first- and second-line settings, using intercalated, sequential, and concurrent treatment strategies. As would be expected, such strategies were most efficacious in patients with the activating EGFR mutations associated with response to an EGFR TKI. In the studies that compared a pemetrexed-EGFR TKI combination with pemetrexed alone or the EGFR TKI alone, the pemetrexed-EGFR TKI combination was more efficacious than the single-agent regimens. The pemetrexed-EGFR TKI combinations were generally associated with a higher incidence of grade 3/4 treatment-related adverse events than the single-agent regimens; however, such toxicities were clinically manageable. Future studies of pemetrexed-EGFR TKI combinations should focus on optimizing treatment strategies in patients with activating EGFR mutations.

Combination of chemotherapy and gefitinib as first-line treatment for patients with advanced lung adenocarcinoma and sensitive EGFR mutations: A randomized controlled trial

To explore the optimal treatment strategy for patients who harbor sensitive EGFR mutations, a head-to-head study was performed to compare chemotherapy and gefitinib in combination or with either agent alone as first-line therapy, in terms of efficacy and safety. A total of 121 untreated patients with advanced lung adenocarcinoma who harbored sensitive EGFR mutations were randomly assigned to receive gefitinib combined with pemetrexed and carboplatin, pemetrexed plus carboplatin or gefitinib alone. The progression-free survival (PFS) of patients in the combination group (17.5 months, 95% CI, 15.3-19.7) was longer than that of patients in the chemotherapy group (5.7 months, 95% CI, 5.2-6.3) or gefitinib (11.9 months, 95% CI, 9.1-14.6) group. The (hazard ratios) HRs of PFS for the combination group vs. chemotherapy and gefitinib groups were 0.16 (95% CI, 0.09-0.29, p < 0.001) and 0.48 (95% CI, 0.29-0.78, p = 0.003), respectively. The overall response rate (ORR) in the combination therapy group, chemotherapy group and the gefitinib group was 82.5%, 32.5% and 65.9%, respectively. The combinational strategy resulted in longer overall survival (OS) than chemotherapy (HR = 0.46, p = 0.016) or gefitinib (HR = 0.36, p = 0.001) alone. Our finding suggested that treatment with pemetrexed plus carboplatin combined with gefitinib could provide better survival benefits for patients with lung adenocarcinoma harboring sensitive EGFR mutations.

Learning from biomedical linked data to suggest valid pharmacogenes

Background

A standard task in pharmacogenomics research is identifying genes that may be involved in drug response variability, i.e., pharmacogenes. Because genomic experiments tended to generate many false positives, computational approaches based on the use of background knowledge have been proposed. Until now, only molecular networks or the biomedical literature were used, whereas many other resources are available.

Method

We propose here to consume a diverse and larger set of resources using linked data related either to genes, drugs or diseases. One of the advantages of linked data is that they are built on a standard framework that facilitates the joint use of various sources, and thus facilitates considering features of various origins. We propose a selection and linkage of data sources relevant to pharmacogenomics, including for example DisGeNET and Clinvar. We use machine learning to identify and prioritize pharmacogenes that are the most probably valid, considering the selected linked data. This identification relies on the classification of gene–drug pairs as either pharmacogenomically associated or not and was experimented with two machine learning methods –random forest and graph kernel–, which results are compared in this article.

Results

We assembled a set of linked data relative to pharmacogenomics, of 2,610,793 triples, coming from six distinct resources. Learning from these data, random forest enables identifying valid pharmacogenes with a F-measure of 0.73, on a 10 folds cross-validation, whereas graph kernel achieves a F-measure of 0.81. A list of top candidates proposed by both approaches is provided and their obtention is discussed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13326-017-0125-1) contains supplementary material, which is available to authorized users.

Randomized Phase II Trial of Gefitinib With and Without Pemetrexed as First-Line Therapy in Patients With Advanced Nonsquamous Non–Small-Cell Lung Cancer With Activating Epidermal Growth Factor Receptor Mutations

Purpose

To determine whether the addition of pemetrexed to gefitinib (P+G) provides clinical benefit, compared with gefitinib monotherapy, in patients with advanced nonsquamous (NS) non–small-cell lung cancer (NSCLC) and activating epidermal growth factor receptor (EGFR) mutations.

Patients and Methods

Chemotherapy-naïve for advanced NSCLC patients from China, Japan, Korea, and Taiwan (35 sites) with advanced, EGFR-mutant, NS NSCLC were randomly assigned (2:1; computer-generated, interactive voice response) to open-label pemetrexed (500 mg/m2 on day 1 of every 21-day cycle) plus gefitinib (250 mg/d [n = 129]) or gefitinib alone (n = 66). The primary end point was progression-free-survival (PFS); secondary end points were time to progressive disease, overall survival, tumor response rates, duration of response, and safety. All end points were assessed in the intent-to-treat and safety population (P+G, n = 126; gefitinib alone, n = 65).

Results

PFS was significantly longer with P+G (median, 15.8 months; 95% CI, 12.6 to 18.3 months) than with gefitinib (median, 10.9 months; 95% CI, 9.7 to 13.8 months; adjusted hazard ratio [HR], 0.68; 95% CI, 0.48 to 0.96; one-sided P = .014; two-sided P = .029). Results of EGFR exon 19 deletion and EGFR exon 21 L858R point mutation subgroup analyses were consistent with the intent-to-treat result. P+G, compared with gefitinib alone, resulted in significantly longer time to progressive disease (median, 16.2 v 10.9 months, respectively; HR, 0.66; 95% CI, 0.47 to 0.93) and numerically longer duration of response (median, 15.4 v 11.3 months, respectively; HR, 0.74; 95% CI, 0.50 to 1.08). Tumor response rates did not differ. Overall survival data are immature. Drug-related grade 3 or 4 adverse events were more common with P+G, but toxicities were manageable.

Conclusion

P+G improved PFS compared with gefitinib alone in East Asian patients with advanced NS NSCLC and activating EGFR mutations. This combination may offer EGFR mutation–positive patients new treatment options and improved clinical outcomes compared with the current standard of care.

Study of Gefitinib and Pemetrexed as First-Line Treatment in Patients with Advanced Non-Small Cell Lung Cancer Harboring EGFR Mutation

To evaluate the efficacy and safety of a combination regimen of gefitinib and pemetrexed as first-line chemotherapy in advanced EGFR-mutated non-small cell lung cancer (NSCLC) patients. Patients and methods Patients with advanced non-squamous NSCLC harboring asensitive EGFR mutation were included in this study and randomly divided into gefitinib + placebo group and gefitinib + pemetrexed group. Pemetrexed or placebo was administered on day 1 at a dose of 500 mg/m(2), and gefitinib was sequentially administered on days 2 ~ 16. This treatment regimen was repeated every 3 weeks until disease progression. All investigators and participants were masked to treatment allocation. The overall response rate (ORR) and disease control rate (DCR) of gefitinib + pemetrexed group were higher than that of gefitinib + placebo group but only the difference of DCR between two groups was statistically significant (P < 0.05). The median progression-free survival (PFS) of gefitinib + placebo group and gefitinib + pemetrexed group were 14.0 months vs. 18 months respectively and the difference was statistically significant (P < 0.05). The 2-year PFS rates of gefitinib + pemetrexed group (20.00 %) was higher than that of gefitinib + placebo group (8.89 %) and the difference was statistically significant (P < 0.05). The median overall survival (OS) of gefitinib + placebo group and gefitinib + pemetrexed group were 32.0 months vs. 34 months respectively and the difference was not statistically significant (P > 0.05). The 3-year OS rates of gefitinib + pemetrexed group (44.44 %) was higher than that of gefitinib + placebo group (35.56 %) but the difference was not statistically significant (P > 0.05). Major grade 3 or 4 hematological toxicities included neutropenia, leukopenia and anemia. The main grade 3 or 4 non-hematological toxicities were infection, increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, fatigue, diarrhea and pneumonitis. The difference of toxicities between two groups was not statistically significant (P > 0.05). The combination regimen of gefitinib + pemetrexed used in this study showed a higher ORR and DCR, longer median PFS and acceptable toxicity.

Enhanced gefitinib-induced repression of the epidermal growth factor receptor pathway by ataxia telangiectasia-mutated kinase inhibition in non-small-cell lung cancer cells

The epidermal growth factor receptor (EGFR) tyrosine kinase signaling pathways regulate cellular activities. The EGFR tyrosine kinase inhibitors (EGFR‐TKIs) repress the EGFR pathway constitutively activated by somatic EGFR gene mutations and have drastically improved the prognosis of non‐small‐cell lung cancer (NSCLC) patients. However, some problems, including resistance, remain to be solved. Recently, combination therapy with EGFR‐TKIs and cytotoxic agents has been shown to improve the prognosis of NSCLC patients. To enhance the anticancer effects of EGFR‐TKIs, we examined the cross‐talk of the EGFR pathways with ataxia telangiectasia‐mutated (ATM) signaling pathways. ATM is a key protein kinase in the DNA damage response and is known to phosphorylate Akt, an EGFR downstream factor. We found that the combination of an ATM inhibitor, KU55933, and an EGFR‐TKI, gefitinib, resulted in synergistic cell growth inhibition and induction of apoptosis in NSCLC cell lines carrying the sensitive EGFR mutation. We also found that KU55933 enhanced the gefitinib‐dependent repression of the phosphorylation of EGFR and/or its downstream factors. ATM inhibition may facilitate the gefitinib‐dependent repression of the phosphorylation of EGFR and/or its downstream factors, to exert anticancer effects against NSCLC cells with the sensitive EGFR mutation.

Phase II trial of carboplatin, S-1, and gefitinib as first-line triplet chemotherapy for advanced non-small cell lung cancer patients with activating epidermal growth factor receptor mutations

Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), is an effective treatment for advanced non-small cell lung cancer (NSCLC) in patients with activating EGFR mutations. However, there have been little evidence-based studies of gefitinib in combination with platinum-doublet therapy in these patients. We performed a phase II trial to determine the efficacy and safety of triplet chemotherapy with gefitinib, carboplatin, and S-1 as a first-line treatment. This was a multicentre, single-arm, phase II trial of carboplatin, S-1, and gefitinib in advanced NSCLC patients with activating EGFR mutations. Patients received four courses of these drugs in 3-4 week cycles. In each cycle, carboplatin (area under curve = 5) was administered on day 1, S-1 (80 mg/m(2)) on days 1-14, and gefitinib (250 mg) every day. Subsequently, the same regimen without carboplatin was administered until disease progression or unacceptable toxicity occurred. The 1-year progression-free survival (PFS) was the primary endpoint, while response rate (RR), PFS, overall survival (OS), and safety were secondary endpoints. Thirty-five patients were enrolled into this study. The 1-year PFS was 74.3% and the overall RR was 85.7%. The median PFS for all patients was 17.6 months (95% confidence interval 15.5-∞), but the median OS was not reached, because 28 patients were still alive after a median follow-up time of 21.4 months. Haematological adverse events (grade 3 or higher) included neutropaenia (17.1%), thrombocytopenia (14.3%), and anaemia (5.7%), while non-haematological adverse events (grade 3 or higher) included elevated aminotransferase (20.0%), diarrhoea (14.3%), and febrile neutropaenia (2.9%). No interstitial lung disease or treatment-related deaths occurred. Combination chemotherapy with carboplatin, S-1, and gefitinib is efficacious and well tolerated as a first-line treatment in advanced NSCLC patients with activating EGFR mutations.

Favorable effect of the combination of vinorelbine and dihydropyrimidine dehydrogenase‑inhibitory fluoropyrimidine in EGFR‑mutated lung adenocarcinoma: retrospective and in vitro studies

Although cytotoxic chemotherapy is essential in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC), it is unclear which regimen is most effective. We retrospectively compared the efficacy of standard platinum-based chemotherapy with that of combination chemotherapy using vinorelbine (VNR) plus dihydropyrimidine dehydrogenase-inhibitory fluoropyrimidine (DIF) in EGFR-mutated lung adenocarcinomas, and we investigated a potential mechanism by which the combination chemotherapy of VNR + DIF was favorable in the treatment of EGFR-mutated lung adenocarcinoma in vitro. In our retrospective analysis, the response rate and disease control rate afforded by the VNR + DIF treatment tended to be better than those by platinum-based chemotherapy, and the progression-free survival of the 24 VNR + DIF-treated patients was significantly longer than that of the 15 platinum-based chemotherapy patients. In EGFR-mutated PC9 cells, VNR induced EGFR dephosphorylation at a clinically achievable concentration. 1BR3-LR cells, a line of fibroblast cells transfected with a mutant EGFR construct, were completely resistant to gefitinib in the medium containing 10% fetal bovine serum (FBS), whereas the sensitivity of these cells to gefitinib was increased in 0.5% FBS-containing medium. Similarly, the sensitivity of 1BR3-LR cells to VNR was increased when they were cultured in low-serum condition. In addition, sodium orthovanadate (Na₃VO₄) inhibited the EGFR dephosphorylation induced by VNR or gefitinib and suppressed the cell growth inhibition by these agents in PC9 cells. VNR and gefitinib showed synergistic cell growth inhibition in combination with 5-fluorouracil (5-FU) in PC9 cells. We propose that the EGFR dephosphorylation induced by VNR is related to cell growth inhibitory activity of VNR, and that this is one of the mechanisms of the synergistic effect of VNR + 5-FU in EGFR-mutated lung cancer cells. In conclusion, the combination chemotherapy of VNR + DIF may be a promising treatment for NSCLC patients with EGFR mutations.

Synergistic anti-tumor effects of a novel phosphatidyl inositol-3 kinase/mammalian target of rapamycin dual inhibitor BGT226 and gefitinib in non-small cell lung cancer cell lines

Epidermal growth factor receptor (EGFR) and PI3K/mTOR pathway are drug targets for non-small cell lung cancer (NSCLC). Herein, we investigated anti-tumor effects of the combination of BGT226, a novel PI3K/mTOR dual inhibitor, and gefitinib on NSCLC cell lines which are high sensitive to gefitinib. The combination of BGT226 and gefitinib exhibited supra-additive growth inhibitory effects in PC-9 and HCC827 cells. Apoptotic induction and the inhibition of PI3K/mTOR signaling were enhanced by the combination. Significant tumor growth suppression was observed in xenograft model by the combination. These results suggest that the combination is effective in EGFR inhibitor-sensitive NSCLC therapy.

Enhancement of 5-fluorouracil-induced cytotoxicity by leucovorin in 5-fluorouracil-resistant gastric cancer cells with upregulated expression of thymidylate synthase

BACKGROUND

Elucidation of the mechanisms by which gastric cancer cells acquire resistance to 5-fluorouracil (5FU) may provide important clues to the development of effective chemotherapy for 5FU-resistant gastric cancer

METHODS

Four 5FU-resistant cell lines (MKN45/5FU, MKN74/5FU, NCI-N87/5FU, and KATOIII/5FU) were established by continuous exposure of the cells to progressively increasing concentrations of 5FU for about 1 year. Then, mRNA expression levels of four genes associated with 5FU metabolism, i.e., thymidylate synthase (TS), dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase, were quantitatively evaluated by real-time reverse transcriptase-polymerase chain reaction. In addition, TS protein expression was measured by Western blot analysis.

RESULTS

As compared with the parent cell lines, the 5FU-resistant cell lines showed 3.8- to 11.6-fold higher resistance to 5FU, as well as 1.9- to 3.5-fold higher TS mRNA expression and 1.6- to 7.1-fold higher TS protein expression. In contrast, the expressions of other genes did not differ significantly among the cell lines. The cytotoxicity of 5FU was enhanced 2.3- to 2.8 fold by leucovorin (LV) against three of the four 5FU-resistant cell lines.

CONCLUSIONS

Collectively, LV enhanced the cytotoxicity of 5FU not only against the parent gastric cancer cell lines, but also against the 5FU-resistant cell lines, even those with elevated TS expression levels. These results suggest that clinical studies of a combination of 5FU and LV are warranted in patients who have recurrent gastric cancer after 5FU-based therapy.

Cbl-b enhances sensitivity to 5-fluorouracil via EGFR- and mitochondria-mediated pathways in gastric cancer cells

5-Fluorouracil (5-FU) is an essential component of anticancer chemotherapy against gastric cancer. However, the response rate of single drug is still limited. The ubiquitin ligase Cbl-b is a negative regulator of growth factor receptor signaling and is involved in the suppression of cancer cell proliferation. However, whether Cbl-b could affect 5-FU sensitivity remains unclear. The present study showed that Cbl-b knockdown caused higher proliferation concomitant with the decrease of apoptosis induced by 5-FU treatment in gastric cancer cell. Further mechanism investigation demonstrated that Cbl-b knockdown caused significant increase of phosphorylation of EGFR, ERK and Akt, decrease of mitochondrial membrane potential, and increase of expression ratio of Bcl-2/Bax. These results suggest that Cbl-b enhances sensitivity to 5-FU via EGFR- and mitochondria-mediated pathways in gastric cancer cells.

53BP1 sensitizes breast cancer cells to 5-fluorouracil

Chemoresistance of breast cancer is a worldwide problem for breast cancer and the resistance to chemotherapeutic agents frequently led to the subsequent recurrence and metastasis. In our previous study, we have found that 53BP1 showed a gradual decrease during the progression of breast cancer and loss of 53BP1 was associated with metastasis and poor prognosis in breast cancer. Here we aimed to reveal whether 53BP1 could sensitize breast cancer to 5-Fu. We found that ectopic expression of 53BP1 can significantly sensitize breast cancer cells to 5-Fu while knockdown of 53BP1 conferred the resistance. The in vivo experiments confirmed that overexpression of 53BP1 in combination with 5-Fu markedly inhibited growth of xenotransplanted tumors in nude mice when compared to either agent alone. Furthermore, we demonstrated that 53BP1 regulated the sensitivity to 5-Fu through thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPYD). The present studies provide a new clue that combination of 5-Fu and 53BP1 could be a potential novel targeted strategy for overcoming breast cancer chemoresistance.

Mechanistic evaluation of the signaling events regulating curcumin-mediated chemosensitization of breast cancer cells to 5-fluorouracil

5-Fluorouracil (5-FU) is the first rationally designed antimetabolite, which achieves its therapeutic efficacy through inhibition of the enzyme thymidylate synthase (TS), which is essential for the synthesis and repair of DNA. However, prolonged exposure to 5-FU induces TS overexpression, which leads to 5-FU resistance in cancer cells. Several studies have identified curcumin as a potent chemosensitizer against chemoresistance induced by various chemotherapeutic drugs. In this study, we report for the first time, with mechanism-based evidences, that curcumin can effectively chemosensitize breast cancer cells to 5-FU, thereby reducing the toxicity and drug resistance. We found that 10 μM 5-FU and 10 μM curcumin induces a synergistic cytotoxic effect in different breast cancer cells, independent of their receptor status, through the enhancement of apoptosis. Curcumin was found to sensitize the breast cancer cells to 5-FU through TS-dependent downregulation of nuclear factor-κB (NF-κB), and this observation was confirmed by silencing TS and inactivating NF-κB, both of which reduced the chemosensitizing efficacy of curcumin. Silencing of TS suppressed 5-FU-induced NF-κB activation, whereas inactivation of NF-κB did not affect 5-FU-induced TS upregulation, confirming that TS is upstream of NF-κB and regulates the activation of NF-κB in 5-FU-induced signaling pathway. Although Akt/PI3kinase and mitogen-activated protein kinase pathways are activated by 5-FU and downregulated by curcumin, they do not have any role in regulating the synergism. As curcumin is a pharmacologically safe and cost-effective compound, its use in combination with 5-FU may improve the therapeutic index of 5-FU, if corroborated by in vivo studies and clinical trials.

Human ether-à-go-go gene potassium channels are regulated by EGFR tyrosine kinase

Human ether á-go-go gene potassium channels (hEAG1 or Kv10.1) are expressed in brain and various human cancers and play a role in neuronal excitement and tumor progression. However, the functional regulation of hEAG channels by signal transduction is not fully understood. The present study was therefore designed to investigate whether hEAG1 channels are regulated by protein tyrosine kinases (PTKs) in HEK 293 cells stably expressing hEAG1 gene using whole-cell patch voltage-clamp, immunoprecipitation, Western blot, and mutagenesis approaches. We found that the selective epidermal growth factor receptor (EGFR) kinase inhibitor AG556 (10 μM), but not the platelet growth factor receptor (PDGFR) kinase inhibitor AG1295 (10 μM) or the Src-family inhibitor PP2 (10 μM), can inhibit hEAG1 current, and the inhibitory effect can be reversed by the protein tyrosine phosphatase (PTP) inhibitor orthovanadate. Immunoprecipitation and Western blot analysis revealed that tyrosine phosphorylation level of hEAG1 channels was reduced by AG556, and the reduction was significantly countered by orthovanadate. The hEAG1 mutants Y90A, Y344A and Y485A, but not Y376A and Y479A, exhibited reduced response to AG556. Interestingly, the inhibition effect of AG556 was lost in triple mutant hEAG1 channels at Y90, Y344, and Y485 with alanine. These results demonstrate for the first time that hEAG1 channel activity is regulated by EGFR kinase at the tyrosine residues Tyr90, Try344, and Try485. This effect is likely involved in regulating neuronal activity and/or tumor growth.

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.

Three-gene predictor of clinical outcome for gastric cancer patients treated with chemotherapy

To identify transcriptional profiles predictive of the clinical benefit of cisplatin and fluorouracil (CF) chemotherapy to gastric cancer patients, endoscopic biopsy samples from 96 CF-treated metastatic gastric cancer patients were prospectively collected before therapy and analyzed using high-throughput transcriptional profiling and array comparative genomic hybridization. Transcriptional profiling identified 917 genes that are correlated with poor patient survival after CF at P<0.05 (poor prognosis signature), in which protein synthesis and DNA replication/recombination/repair functional categories are enriched. A survival risk predictor was then constructed using genes, which are included in the poor prognosis signature and are contained within identified genomic amplicons. The combined expression of three genes—MYC, EGFR and FGFR2—was an independent predictor for overall survival of 27 CF-treated patients in the validation set (adjusted P=0.017), and also for survival of 40 chemotherapy-treated gastric cancer patients in a published data set (adjusted P=0.026). Thus, combined expression of MYC, EGFR and FGFR2 is predictive of poor survival in CF-treated metastatic gastric cancer patients.

Synergistic antitumor effect of S-1 and HER2-targeting agents in gastric cancer with HER2 amplification

Amplification of human epidermal growth factor receptor 2 (HER2) has been detected in 20% to 30% of gastric cancers and is associated with a poor outcome. Combination therapies with HER2-targeting agents and cytotoxic agents are considered a potential therapeutic option for gastric cancer with HER2 amplification. We have now investigated the effects of combination treatment with the oral fluoropyrimidine S-1 and the HER2-targeting agents lapatinib or trastuzumab in gastric cancer cells with or without HER2 amplification. We used 5-fluorouracil (5FU) instead of S-1 for in vitro experiments, given that tegafur, a component of S-1, is metabolized to 5FU in the liver. The combination of 5FU and HER2-targeting agents synergistically inhibited cell proliferation and exhibited an enhanced proapoptotic effect in gastric cancer cells with HER2 amplification, but not in those without it. Lapatinib or trastuzumab also induced downregulation of thymidylate synthase (TS) expression and activity only in cells with HER2 amplification. The combination of 5FU and TS depletion by RNA interference also exhibited an enhanced proapoptotic effect in cells with HER2 amplification. These observations thus suggest that lapatinib-induced or trastuzumab-induced downregulation of TS is responsible, at least in part, for the synergistic antitumor effect of combined treatment with 5FU and HER2-targeting agents. The antitumor effect of the combination of S-1 and HER2-targeting agents in vivo was also greater than that of either drug alone. Our preclinical findings thus indicate that the combination of S-1 and HER2-targeting agents is a promising treatment option for gastric cancer with HER2 amplification.