Enhancement of tumor radioresponse by combined treatment with gefitinib (Iressa, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, is accompanied by inhibition of DNA damage repair and cell growth in oral cancer

Appropriate delay of primary tumour radiotherapy may lead to better long-term overall survival for non-small cell lung cancer treated with EGFR-TKIs

PURPOSE

The most appropriate time of primary tumor radiotherapy in non-small cell lung cancer(NSCLC) with EGFR-TKIs remains unclear. The aim of this study was to investigate the effect of the time factor of primary tumor radiotherapy on long-term overall survival(OS)and provide a theoretical basis for further clinical research.

PATIENTS AND METHODS

In total, 238 patients with EGFR-TKIs and OS ≥ 12 months were statistically analysed. Patients were grouped: the D group without primary tumor radiotherapy and the R group with it.The R group were divided into three groups according to the interval between the start of EGFR-TKIs and the start of primary tumor radiotherapy: R0 - 30(<30 days), R30 - PD(≥ 30 days and disease stable), and RPD(radiotherapy after disease progression). The Kaplan-Meier method and log-rank test were used for survival analyses. Exploratory landmark analyses were investigated.

RESULTS

The OS rates at 1, 2, 3, 5 years for the R group and D group were 96.8%, 62.9%, 38.3%, 17.1%, and 95.6%, 37.7%, 21.8%, 2.9%, respectively; the corresponding MST was 29 months(95% CI: 24.3-33.7) for the R group and 22 months(95% CI: 20.4-23.6) for the D group (χ2 = 13.480, p<0.001). Multivariate analysis revealed that primary tumor radiotherapy was independent predictors of prolonged OS.Among the four groups, The R30 - PD appeared to have the best OS (D, χ2 = 19.307, p<0.001;R0 - 30, χ2 = 11.687, p = 0.01; RPD, χ2 = 4.086, p = 0.043). Landmark analyses(22 months) showed the R30 - PD group had a significant long-term OS.The incidence of radiation pneumonitis ≥ grade 2 was17.3%(n = 19)and radiation esophagitis ≥ grade 2 was observed in 32 patients(29.1%).

CONCLUSIONS

Our results showed that primary tumour radiotherapy may prolong long-term OS with acceptable toxicities. Appropriate delay(R30 - PD)of primary tumour radiotherapy may be the best choice.Premature radiotherapy(R0 - 30) and radiotherapy after disease progression (RPD)may not be reasonable for long-term OS.

Re-evaluating the risk factors for radiation pneumonitis in the era of immunotherapy

As one of the common complications of radiotherapy, radiation pneumonia (RP) limits the prognosis of patients. Therefore, better identifying the high-risk factors that lead to RP is essential to effectively prevent its occurrence. However, as lung cancer treatment modalities are being replaced and the era of immunotherapy has arrived, literature that reviews the parameters and mode of radiotherapy, chemotherapy drugs, targeted drugs and current hot immune checkpoint inhibitors related to RP is lacking. This paper summarizes the risk factors for radiation pneumonia by retrieving and analysing previously published literature and the results of large clinical trials. The literature primarily included retrospective analyses, including clinical trials in different periods and a part of the literature review. A systematic literature search of Embase, PubMed, Web of Science, and Clinicaltrials.gov was performed for relevant publications up to 6 Dec. 2022. Search keywords include, but are not limited to, "radiation pneumonia", "pneumonia", "risk factors", "immunotherapy", etc. The factors related to RP in this paper include physical parameters of radiotherapy, including V₅, V₂₀, and MLD; chemoradiotherapy mode and chemotherapy drugs, including paclitaxel and gemcitabine; EGFR-TKI; ALK inhibitors; antiangiogenic drugs; immune drugs and the underlying disease of the patient. We also introduce the possible mechanism of RP. In the future, we hope that this article not only sounds the alarm for clinicians but also helps to identify a method that can effectively intervene and reduce the occurrence of RP, significantly improve the quality of life and prognosis of patients, and more effectively improve the therapeutic effect of radiation therapy.

Survival benefit of thoracic radiotherapy plus EGFR-TKIs in patients with non-oligometastatic advanced non-small-cell lung cancer: a single-center retrospective study

Objectives:

The study aims to evaluate the efficacy and safety of thoracic radiotherapy in epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-treated patients with stage IV non-small-cell lung cancer (NSCLC).

Methods:

Patients with non-oligometastatic NSCLC harboring EGFR mutations were recruited. All patients received the first-generation TKI treatment with or without radiotherapy. The irradiated sites included primary and/or metastatic lesions. Of all the patients who underwent thoracic radiotherapy, some received radiotherapy before EGFR-TKI resistance, others received radiotherapy after progressive disease.

Results:

No statistically significant difference was observed in progression-free survival (PFS) (median 14.7 versus 11.2 months, p = 0.075) or overall survival (OS) (median 29.6 versus 40.6 months, p = 0.116) between patients treated with EGFR-TKIs alone and those with additional radiotherapy to any sites. However, EGFR inhibitors with thoracic radiation significantly improved OS (median 47.0 versus 31.0 months, p < 0.001) but not PFS (median 13.9 versus 11.9 months, p = 0.124). Moreover, longer PFS (median 18.3 versus 8.5 months, p < 0.001) was achieved in the preemptive thoracic radiation cohort than in the delayed thoracic radiation cohort. However, OS was similar between the two cohorts (median 40.6 versus 52.6 months, p = 0.124). The lower incidence rate of grade 1–2 pneumonitis occurred in preemptive radiation cohort (29.8% versus 75.8%, p < 0.001).

Conclusion:

Non-oligometastatic NSCLC patients with EGFR mutations benefited from thoracic radiotherapy while using EGFR inhibitors. Preemptive thoracic radiotherapy could be a competitive first-line therapeutic option due to superior PFS and favorable safety.

The Value of Radiotherapy for Advanced Non-Small Cell Lung Cancer With Oncogene Driver-Mutation

Due to the widespread use of tyrosine kinase inhibitors (TKIs), which have largely supplanted cytotoxic chemotherapy as the first-line therapeutic choice for patients with advanced non-small cell lung cancer (NSCLC) who have oncogene driver mutations, advanced NSCLC patients with oncogene driver mutations had much long median survival. However, TKIs’ long-term efficacy is harmed by resistance to them. TKIs proved to have a limited potential to permeate cerebrospinal fluid (CSF) as well. Only a small percentage of plasma levels could be found in CSF at usual doses. Therefore, TKIs monotherapy may have a limited efficacy in individuals with brain metastases. Radiation has been demonstrated to reduce TKIs resistance and disrupt the blood-brain barrier (BBB). Previous trials have shown that local irradiation for bone metastases might improve symptoms, in addition, continuous administration of TKIs combined with radiotherapy was linked with beneficial progression-free survival (PFS) and overall survival (OS) for oligometastasis or bone metastasis NSCLC with oncogene driver mutations. The above implied that radiotherapy combined with targeted therapy may have a synergistic impact in patients with advanced oncogene driver-mutated NSCLC. The objective of this article is to discuss the value of radiotherapy in the treatment of those specific individuals.

Thoracic surgery improved overall survival in patients with stage IIIB-IV epidermal growth factor receptor-mutant lung adenocarcinoma who received and responded to tyrosine kinase inhibitor treatment

PURPOSE

No large-scale, prospective, randomized study has evaluated the effect of thoracic surgery on patients with unresectable stage IIIB-IV epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma who received and responded to EGFR tyrosine kinase inhibitor (TKI) treatment. Therefore, we designed a propensity-score-matched, nationwide, population-based, cohort study to investigate the effects of thoracic surgery on patients with EGFR-mutant lung adenocarcinoma.

PATIENTS AND METHODS

We included patients with unresectable stage IIIB-IV EGFR-mutant lung adenocarcinoma and categorized them into two groups according to their treatment modalities and compared their outcomes: the case group consisted of patients who underwent thoracic surgery for lung tumors after receiving and responding to EGFR-TKI treatment and the comparison group consisted of patients who received EGFR-TKI treatment alone until tumor progression. Patients in both groups were matched at a ratio of 1:4.

RESULTS

The matching process yielded a final cohort of 1395 patients (279 and 1,116 in the case and comparison groups, respectively) who were eligible for further analysis. According to multivariable Cox regression analyses, the adjusted hazard ratio (aHR; 95% confidence interval [CI]) for thoracic surgery for lung tumors after EGFR-TKI use and tumor response (group 2) compared with EGFR-TKI treatment alone (group 1) was 0.445 (0.351-0.564).

CONCLUSIONS

Thoracic surgery prolonged overall survival in patients with unresectable stage IIIB-IV EGFR-mutant lung adenocarcinoma who received and responded to EGFR-TKI treatment.

Impact of Tenascin-C on Radiotherapy in a Novel Syngeneic Oral Squamous Cell Carcinoma Model With Spontaneous Dissemination to the Lymph Nodes

Radiotherapy, the most frequent treatment of oral squamous cell carcinomas (OSCC) besides surgery is employed to kill tumor cells but, radiotherapy may also promote tumor relapse where the immune-suppressive tumor microenvironment (TME) could be instrumental. We established a novel syngeneic grafting model from a carcinogen-induced tongue tumor, OSCC13, to address the impact of radiotherapy on OSCC. This model revealed similarities with human OSCC, recapitulating carcinogen-induced mutations found in smoking associated human tongue tumors, abundant tumor infiltrating leukocytes (TIL) and, spontaneous tumor cell dissemination to the local lymph nodes. Cultured OSCC13 cells and OSCC13-derived tongue tumors were sensitive to irradiation. At the chosen dose of 2 Gy mimicking treatment of human OSCC patients not all tumor cells were killed allowing to investigate effects on the TME. By investigating expression of the extracellular matrix molecule tenascin-C (TNC), an indicator of an immune suppressive TME, we observed high local TNC expression and TIL infiltration in the irradiated tumors. In a TNC knockout host the TME appeared less immune suppressive with a tendency towards more tumor regression than in WT conditions. Altogether, our novel syngeneic tongue OSCC grafting model, sharing important features with the human OSCC disease could be relevant for future anti-cancer targeting of OSCC by radiotherapy and other therapeutic approaches.

Primary Tumor Radiotherapy During EGFR-TKI Disease Control Improves Survival of Treatment Naïve Advanced EGFR-Mutant Lung Adenocarcinoma Patients

Background

Whether radiotherapy only for primary lung tumor (RTPLT) after epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) therapy improves survival of treatment naïve advanced EGFR-mutant lung adenocarcinoma (LAD) patients with/without polymetastasis.

Materials and Methods

This was a retrospective, single-center, observational study. Patients with stage IIIB-IV EGFR-mutant LAD with disease control by EGFR-TKI therapy were divided into curative RTPLT, and control, without radiotherapy (WRTPLT) groups.

Results

A total of 138 patients were enrolled; 46 in the RTPLT group and 92 in the WRTPLT group. Amongst them, 37% had oligometastasis, and 26.1% brain metastasis. The RTPLT group had both significantly longer progression-free survival (PFS) (27.5 months [95% CI 18.1–36.9] vs 10.9 months [95% CI 6.3–15.5], P<0.001) and overall survivor (OS) (NR [95% CI NR-NR] vs 38.0 months [95% CI 31.2–44.8], P<0.001), respectively, when compared to the WRTPLT group. In multivariate analysis, the adjusted HR of radiotherapy on PFS was 0.30 (0.19–0.47) and on OS, 0.11 (0.04–0.30). Patients with oligometastasis had significantly longer PFS than those with polymetastasis with an HR of 0.35 (0.14–0.85), P=0.02. Patients with either oligometastasis or polymetastasis had significant longer PFS when undergoing radiotherapy than those without (both P<0.05). An EGFR-TKI to radiotherapy interval <24 weeks seemed more beneficial (P=0.097). Radiation pneumonitis comprised 32 (69.6%), 12 (26.1%), and two (4.3%) cases of common terminology criteria grade I, II, and III, respectively.

Conclusion

Curative RTPLT can prolong survival in patients with LAD following EGFR-TKI disease control, both involving oligometastasis and polymetastasis. RTPLT within 24 weeks after EGFR-TKI initiation appeared to be more beneficial with tolerable radiation pneumonitis.

RAS/MAPK signaling functions in oxidative stress, DNA damage response and cancer progression

Mitogen-activated protein kinase (MAPK) signaling pathways organize a great constitution network that regulates several physiological processes, like cell growth, differentiation, and apoptotic cell death. Due to the crucial importance of this signaling pathway, dysregulation of the MAPK signaling cascades is involved in the pathogenesis of various human cancer types. Oxidative stress and DNA damage are two important factors which in common lead to carcinogenesis through dysregulation of this signaling pathway. Reactive oxygen species (ROS) are a common subproduct of oxidative energy metabolism and are considered to be a significant physiological modulator of several intracellular signaling pathways including the MAPK pathway. Studies demonstrated that the MAP kinases extracellular signal-regulated kinase (ERK) 1/2 and p38 were activated in response to oxidative stress. In addition, DNA damage is a partly common circumstance in cell life and may result in mutation, cancer, and even cell death. Recently, accumulating evidence illustrated that the MEK/ERK pathway is associated with the suitable performance of cellular DNA damage response (DDR), the main pathway of tumor suppression. During DDR, the MEK/ERK pathway is regularly activated, which contributes to the appropriate activation of DDR checkpoints to inhibit cell division. Therefore, the aim of this review is to comprehensively discuss the critical function of MAPK signaling in oxidative stress, DNA damage, and cancer progression.

Concurrent EGFR-TKI and Thoracic Radiotherapy as First-Line Treatment for Stage IV Non-Small Cell Lung Cancer Harboring EGFR Active Mutations

LESSONS LEARNED

This single-arm, phase II study shows that concurrent EGFR-tyrosine kinase inhibitor plus thoracic radiotherapy as the first-line treatment for stage IV non-small cell lung cancer harboring EGFR active mutations provides long-term control for the primary lung lesion, and 1-year progression-free survival (PFS) rate and median PFS are numerically higher than those of the erlotinib monotherapy.Serious adverse events are acceptable, although grade >3 radiation pneumonitis occurred in 20% of patients.

BACKGROUND

Studies show effective local control by EGFR-tyrosine kinase inhibitor (TKI) combined with radiotherapy at metastatic sites in advanced lung cancer harboring EGFR active mutations. Salvage local radiotherapy is associated with prolonged progression-free survival (PFS) in local disease during EGFR-TKI treatment. However, no prospective study has been reported on concurrent EGFR-TKI and radiotherapy for primary lung lesions. This study investigated the efficacy and safety of first-line EGFR-TKI combined with thoracic radiotherapy in treating stage IV non-small cell lung cancer (NSCLC) harboring EGFR active mutations.

METHODS

We conducted a single-arm, phase II clinical trial. Each patient received EGFR-TKI (erlotinib 150 mg or gefitinib 250 mg per day) plus thoracic radiotherapy (54-60 Gy/27-30 F/5.5-6 w) within 2 weeks of beginning EGFR-TKI therapy until either disease progression or intolerable adverse events (AEs) appeared.

RESULTS

From January 2015 to March 2018, 401 patients were screened, and 10 patients (5 male and 5 female) were eligible. These patients had a median age of 55 years (40-75) and median follow-up of 19.8 months (5.8-34). The 1-year PFS rate was 57.1%, median PFS was 13 months, and median time to progression of irradiated lesion (iTTP) was 20.5 months. Objective response rate (ORR), was 50% and disease control rate (DCR) was 100%. The most common grade ≥3 AEs were radiation pneumonitis (20%) and rash (10%). One patient died after rejecting treatment for pneumonitis. The others received a full, systematic course of glucocorticoid therapy. Pneumonitis was all well controlled and did not relapse.

CONCLUSION

Concurrent EGFR-TKI plus thoracic radiotherapy as the first-line treatment for stage IV NSCLC harboring EGFR active mutations shows a long-term control of primary lung lesion. The 1-year PFS rate and median PFS of this combined therapy are numerically higher than those of the erlotinib monotherapy. The risk of serious adverse events is acceptable.

Gold nanoparticles enhance X-ray irradiation-induced apoptosis in head and neck squamous cell carcinoma in vitro

Enhancing the antitumor effect of radiation, while reducing damage to organs, is a significant challenge in radiation therapy for head and neck malignancies. One promising radiosensitizer is gold. The present study aimed to determine whether gold nanoparticles (AuNPs) have the potential to enhance the effects of X-ray irradiation on head and neck cancer cells. The human head and neck carcinoma cell line HSC-3 was used. Total cell number and the levels of cell proliferation and apoptosis were compared between control cells and cells treated with 5-nm AuNPs alone at four concentrations (0.1, 0.4, 1.0 and 10.0 nM), X-ray irradiation alone at three doses (2, 4 and 8 Gy), or a combination of 4 Gy X-ray irradiation and 1.0 nM AuNPs. Analysis of variance and Tukey-Kramer testing were performed to compare the different groups. The total number of cells significantly decreased following 4 and 8 Gy X-ray irradiation, compared with in the control group (control vs. 4Gy, P=2.19×10^-4; control vs. 8Gy, P=1.28×10^-6). The combination of 4 Gy X-ray irradiation and 1.0 nM AuNPs significantly reduced the total number of cells compared with 4 Gy X-ray irradiation alone (P=2.95×10^-4). Cell proliferation was not affected by AuNP treatment alone, 4 Gy X-ray irradiation alone or the combination of X-ray irradiation and AuNPs. The combination of 4 Gy irradiation and 1.0 nM AuNPs significantly increased the number of apoptotic cells compared with 4 Gy irradiation alone (P=0.0261). In conclusion, AuNPs combined with X-ray irradiation enhanced the cytotoxic effect on human head and neck cancer cells in vitro, through the induction of apoptosis, but not inhibition of cell proliferation.

EGF receptor signaling, phosphorylation, ubiquitylation and endocytosis in tumors in vivo

Despite a well-established role for the epidermal growth factor receptor (EGFR) in tumorigenesis, EGFR activities and endocytosis in tumors in vivo have not been studied. We labeled endogenous EGFR with GFP by genome-editing of human oral squamous cell carcinoma cells, which were used to examine EGFR-GFP behavior in mouse tumor xenografts in vivo. Intravital multiphoton imaging, confocal imaging of cryosections and biochemical analysis revealed that localization and trafficking patterns, as well as levels of phosphorylation and ubiquitylation of EGFR in tumors in vivo closely resemble patterns and levels observed in the same cells treated with 20–200 pM EGF in vitro. Consistent with the prediction of low ligand concentrations in tumors, EGFR endocytosis was kinase-dependent and blocked by inhibitors of clathrin-mediated internalization; and EGFR activity was insensitive to Cbl overexpression. Collectively, our data suggest that a small pool of active EGFRs is sufficient to drive tumorigenesis by signaling primarily through the Ras-MAPK pathway.

Evaluation of FGFR3 as a Therapeutic Target in Head and Neck Squamous Cell Carcinoma

BACKGROUND

Although head and neck squamous cell carcinoma (HNSCC) is the sixth most common tumour entity worldwide, it remains a clinical challenge. Large-scale explorative genomic projects have identified several genes as potential targets for therapy, including fibroblast growth factor receptor 3 (FGFR3).

AIMS

The aim of this study was to investigate the biological significance of wild-type and mutated FGFR3 to evaluate its potential as a novel therapeutic target in HNSCC.

METHODS

FGFR3 protein expression was analysed in a large HNSCC tissue cohort (n = 536) and FGFR3 mRNA expression from The Cancer Genome Atlas (TCGA; n = 520). Moreover, FGFR3 wild-type and mutant versions were overexpressed in vitro, and both proliferation and migration was assessed with and without BGJ398 (a specific FGFR1-3 inhibitor) treatment.

RESULTS

Although FGFR3 expression for both cohorts decreased during tumour progression, high FGFR3 expression levels were observed in a small subset of patients. In vitro, FGFR3 overexpression led to increased proliferation, whereas migration was not altered. Moreover, FGFR3-overexpressing cells were more sensitive to BGJ398. Cells overexpressing FGFR3 mutant versions showed increased proliferation compared to wild-type FGFR3 under serum-reduced conditions and were largely as sensitive as the wild-type protein to BGJ398.

CONCLUSIONS

Taken together, the results of this study demonstrate that although FGFR3 expression decreases during HNSSC progression, it plays an important role in tumour cell proliferation and thus may be a potential target for therapy in selected patients suffering from this dismal tumour entity.

Long-term results and recurrence patterns from SCOPE-1: a phase II/III randomised trial of definitive chemoradiotherapy +/- cetuximab in oesophageal cancer

BACKGROUND

The SCOPE-1 study tested the role of adding cetuximab to conventional definitive chemoradiotherapy (dCRT), and demonstrated greater toxicity and worse survival outcomes. We present the long-term outcomes and patterns of recurrence.

METHODS

SCOPE-1 was a phase II/III trial in which patients were randomised to cisplatin 60 mg m-2 (day 1) and capecitabine 625 mg m-2 bd (days 1-21) for four cycles +/- cetuximab 400 mg m-2 day 1 then by 250 mg m-2 weekly. Radiotherapy consisted of 50 Gy/25# given concurrently with cycles 3 and 4. Recruitment was between February 2008 and February 2012, when the IDMC recommended closure on the basis of futility.

RESULTS

About 258 patients (dCRT=129; dCRT+cetuximab (dCRT+C)=129) were recruited from 36 centres. About 72.9% (n=188) had squamous cell histology. The median follow-up (IQR) was 46.2 (35.9-48.3) months for surviving patients. The median overall survival (OS; months; 95% CI) was 34.5 (24.7-42.3) in dCRT and 24.7 (18.6-31.3) in dCRT+C (hazard ratio (HR)=1.25, 95% CIs: 0.93-1.69, P=0.137). Median progression-free survival (PFS; months; 95% CI) was 24.1 (15.3-29.9) and 15.9 (10.7-20.8) months, respectively (HR=1.28, 95% CIs: 0.94-1.75; P=0.114). On multivariable analysis only earlier stage, full-dose RT, and higher cisplatin dose intensity were associated with improved OS.

CONCLUSIONS

The mature analysis demonstrates that the dCRT regimen used in the study provided useful survival outcomes despite its use in patients who were largely unfit for surgery or who had inoperable disease. Given the competing risk of systemic and local failure, future studies should continue to focus on enhancing local control as well as optimising systemic therapy.

Enhancing chemosensitivity in oral squamous cell carcinoma by lentivirus vector-mediated RNA interference targeting EGFR and MRP2

Oral cancer is the eighth most common type of cancer among men worldwide, with an age-standardized rate of 6.3 per 100,000, and is the fourth leading cause of cancer-associated mortality among men in Taiwan. Cisplatin and 5-fluorouracil (5-FU) are two of the most frequently utilized chemotherapy drugs for the treatment of oral cancer. Although oral cancer patients initially benefit from chemotherapy with these drugs, they may develop resistance to them, which worsens their prognosis and reduces survival rates. It has been reported that increased levels of epidermal growth factor receptor (EGFR) and multidrug resistance-associated protein 2 (MRP2) induce drug resistance in numerous types of human cancer. Therefore, the present study employed lentivirus vector-mediated RNA interference (RNAi) in order to target the genes encoding EGFR and MRP2 in the oral squamous cell carcinoma cell line OC2. It was observed that RNAi-mediated downregulation of EGFR or MRP2 increased the sensitivity to 5-FU and cisplatin in OC2 cells. Downregulation of EGFR resulted in significant suppression of OC2 tumor growth following 5-FU administration. However, simultaneous downregulation of the two genes did not further suppress the tumor growth, indicating that MRP2 does not have a significant role in the chemosensitivity of EGFR-downregulated cells to 5-FU. In contrast, downregulation of MRP2 was demonstrated to significantly enhance the therapeutic effects of cisplatin in EGFR-downregulated OC2 tumors. The observation that the expression of MRP2 was positively correlated with the level of cisplatin resistance in cells suggests that RNAi-mediated downregulation of MRP2 may be applicable as a therapeutic approach toward reversing MRP2-dependent cisplatin resistance in oral cancer.

Doubling down on the PI3K-AKT-mTOR pathway enhances the antitumor efficacy of PARP inhibitor in triple negative breast cancer model beyond BRCA-ness

Phosphoinositide 3-kinase (PI3K) pathway, in addition to its pro-proliferative and antiapoptotic effects on tumor cells, contributes to DNA damage repair (DDR). We hypothesized that GDC-0980, a dual PI3K-mammalian target of rapamycin (mTOR) inhibitor, would induce an efficient antitumor effect in BRCA-competent triple negative breast cancer (TNBC) model when combined with ABT888 and carboplatin. Mechanism-based in vitro studies demonstrated that GDC-0980 treatment alone or in combination led to DNA damage (increased pγH2AX(S139); Western blot, immunofluorescence), gain in poly ADP-ribose (PAR), and a subsequent sensitization of BRCA-competent TNBC cells to ABT888 plus carboplatin with a time-dependent 1) decrease in proliferation signals (pAKTT308/S473, pP70S6KT421/S424, pS6RPS235/236), PAR/poly(ADP-ribose) polymerase (PARP) ratios, PAR/pγH2AX ratios, live/dead cell ratios, cell cycle progression, and three-dimensional clonogenic growths and 2) increase in apoptosis markers (cleaved caspases 3 and 9, a pro-apoptotic BH3-only of Bcl-2 family (BIM), cleaved PARP, annexin V). The combination was effective in vitro in BRCA-wild-type PIK3CA-H1047R-mutated BT20 and PTEN-null HCC70 cells. The combination blocked the growth of established xenograft tumors by 80% to 90% with a concomitant decrease in tumor Ki67, CD31, phosphorylated vascular endothelial growth factor receptor, pS6RPS235/236, and p4EBP1T37/46 as well as an increase in cleaved caspase 3 immunohistochemistry (IHC) levels. Interestingly, a combination with GDC-0941, a pan-PI3K inhibitor, failed to block the tumor growth in MDA-MB231. Results demonstrate that the dual inhibition of PI3K and mTOR regulates DDR. In a BRCA-competent model, GDC-0980 enhanced the antitumor activity of ABT888 plus carboplatin by inhibiting both tumor cell proliferation and tumor-induced angiogenesis along with an increase in the tumor cell apoptosis. This is the first mechanism-based study to demonstrate the integral role of the PI3K-AKT-mTOR pathway in DDR-mediated antitumor action of PARP inhibitor in TNBC.

Cancer cell profiling by barcoding allows multiplexed protein analysis in fine-needle aspirates

Immunohistochemistry-based clinical diagnoses require invasive core biopsies and use a limited number of protein stains to identify and classify cancers. We introduce a technology that allows analysis of hundreds of proteins from minimally invasive fine-needle aspirates (FNAs), which contain much smaller numbers of cells than core biopsies. The method capitalizes on DNA-barcoded antibody sensing, where barcodes can be photocleaved and digitally detected without any amplification steps. After extensive benchmarking in cell lines, this method showed high reproducibility and achieved single-cell sensitivity. We used this approach to profile ~90 proteins in cells from FNAs and subsequently map patient heterogeneity at the protein level. Additionally, we demonstrate how the method could be used as a clinical tool to identify pathway responses to molecularly targeted drugs and to predict drug response in patient samples. This technique combines specificity with ease of use to offer a new tool for understanding human cancers and designing future clinical trials.

Nimotuzumab as a radiosensitizing agent in the treatment of high grade glioma: challenges and opportunities

Nimotuzumab is a humanized monoclonal antibody that binds specifically to human epidermal growth factor receptor, blocking receptor activation. Evidence of its radiosensitizing capacity has been widely evaluated. This article integrates published research findings regarding the role of nimotuzumab in the treatment of high grade glioma in combination with radiotherapy or radiochemotherapy in adult and pediatric populations. First, the mechanisms of action of nimotuzumab and its current applications in clinical trials containing both radiation and chemoradiation therapies are reviewed. Second, a comprehensive explanation of potential mechanisms driving radiosensitization by nimotuzumab in experimental settings is given. Finally, future directions of epidermal growth factor receptor targeting with nimotuzumab in combination with radiation containing regimens, based on its favorable toxicity profile, are proposed. It is hoped that this review may provide further insight into the rational design of new approaches employing nimotuzumab as a useful alternative for the therapeutic management of high grade glioma.

Reversion of the ErbB malignant phenotype and the DNA damage response

The ErbB or HER family is a group of membrane bound tyrosine kinase receptors that initiate signal transduction cascades, which are critical to a wide range of biological processes. When over-expressed or mutated, members of this kinase family form homomeric or heteromeric kinase assemblies that are involved in certain human malignancies. Targeted therapy evolved from studies showing that monoclonal antibodies to the ectodomain of ErbB2/neu would reverse the malignant phenotype. Unfortunately, tumors develop resistance to targeted therapies even when coupled with genotoxic insults such as radiation. Radiation treatment predominantly induces double strand DNA breaks, which, if not repaired, are potentially lethal to the cell. Some tumors are resistant to radiation treatment because they effectively repair double strand breaks. We and others have shown that even in the presence of ionizing radiation, active ErbB kinase signaling apparently enhances the repair process, such that transformed cells resist genotoxic signal induced cell death. We review here the current understanding of ErbB signaling and DNA double strand break repair. Some studies have identified a mechanism by which DNA damage is coordinated to assemblies of proteins that associate with SUN domain containing proteins. These assemblies represent a new target for therapy of resistant tumor cells.

[Effect and mechanism of gefitinib inhibition on non-small cell lung cancer radiosensitivity of HCC827 and H358 cell lines]

背景与目的

表皮生长因子受体（epidermal growth factor receptor, EGFR）是决定放疗效应的一个重要因素，其过表达或是下游通路的激活与包括非小细胞肺癌在内的肿瘤的放疗抵抗相关，因而阻断EGFR的信号通路可能会增强放疗敏感性。本研究旨在探讨小分子EGFR酪氨酸激酶抑制剂吉非替尼能否增加肺癌细胞株HCC827和H358的放疗敏感性及其可能的机制。

方法

选取HCC827和H358这两个非小细胞肺癌细胞株，分为单纯X线组和X线+吉非替尼两组。单纯X线组采用单纯X线照射，X线+吉非替尼组经1 μmol/L吉非替尼作用24 h后再行X线照射。克隆形成实验比较两株细胞中不同分组细胞放射敏感性，免疫荧光激光共聚焦显微镜观察X线照射后各时间点细胞核中的磷酸化H2AX（γ-H2AX）及EGFR焦点在细胞中的定位情况，Western blot法检测放疗后胞质胞核蛋白中EGFR的表达。

结果

克隆形成实验中，H358细胞实验组与对照组在各放疗剂量点的SF2值分别为0.355和0.433；HCC827细胞实验组与对照组在各放疗剂量点的SF2值分别为0.223和0.242，差别不明显。激光共聚焦显微镜观察照射4 Gy后各时间段实验组H358细胞核中g-H2AX斑点相比对照组要多，且持续时间更长。而对照组和实验组的HCC827细胞g-H2AX斑点在各时间段并无明显差异；激光共聚焦显微镜观察照射4 Gy后对照组H358的EGFR蛋白在1 h内入核，而经吉非替尼处理后EGFR蛋白几乎不入核；实验组及对照组HCC827细胞的EGFR表达位置均在细胞质中，胞核中很少或者没有，可以认为并无入核现象；Western blot结果显示，H358细胞在经4 Gy放射处理后有入核现象，而预先经吉非替尼处理后，EGFR蛋白几乎不在核内表达而仍位于细胞浆内。对于HCC827细胞，实验组及对照组的EGFR蛋白均在细胞质中表达，胞核中很少或没有，且两组并无明显差异。

结论

吉非替尼可增加肺癌细胞株H358的放射敏感性，这可能与其阻止放疗后EGFR入核、影响放疗后双链断裂（double strand break, DSB）修复有关；而对HCC827细胞无影响，可能与其放疗后EGFR不入核相关。

Targeted therapy in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) of multi-factorial etiopathogenesis is rising worldwide. Treatment-associated toxicity problems and treatment failure in advanced disease stages with conventional therapies have necessitated a focus on alternative strategies. Molecular targeted therapy, with the potential for increased selectivity and fewer adverse effects, hold promise in the treatment of HNSCC. In an attempt to improve outcomes in HNSCC, targeted therapeutic strategies have been developed. These strategies are focusing on the molecular biology of HNSCC in an attempt to target selected pathways involved in carcinogenesis. Inhibiting tumor growth and metastasis by focusing on specific protein or signal transduction pathways or by targeting the tumor microenvironment or vasculature are some of the new approaches. Targeted agents for HNSCC expected to improve the effectiveness of current therapy include EGFR inhibitors (Cetuximab, Panitumumab, Zalutumumab), EGFR tyrosine kinase inhibitors (Gefitinib, Erloitinib), VEGFR inhibitors (Bevacizumab, Vandetanib), and various inhibitors of, e.g., Src-family kinase, PARP, proteasome, mTOR, COX, and heat shock protein. Moreover, targeted molecular therapy can also act as a complement to other existing cancer therapies. Several studies have demonstrated that the combination of targeting techniques with conventional current treatment protocols may improve the treatment outcome and disease control, without exacerbating the treatment related toxicities. Some of the targeted approaches have been proved as promising therapeutic potentials and are already in use, whereas remainder exhibits mixed result and necessitates further studies. Identification of predictive biomarkers of resistance or sensitivity to these therapies remains a fundamental challenge in the optimal selection of patients most likely to benefit from targeted treatment.

Gefitinib, cisplatin, and concurrent radiotherapy for locally advanced head and neck cancer: EGFR FISH, protein expression, and mutational status are not predictive biomarkers

BACKGROUND

Gefitinib was demonstrated to be synergistic with cisplatin and radiotherapy (RT) in in vitro studies. Biomarkers predictive of response to gefitinib in squamous cell head and neck cancer is still lacking.

METHODS

Thirty-one patients with locally advanced and easily accessible primary tumor sites for biopsies were recruited. Gefitinib was started 3 weeks before the start of cisplatin/concurrent radiotherapy (CTRT) and continued during the CTRT phase and thereafter for 4 months as consolidation phase. Two baselines and a repeat tumor sample were taken after 2 weeks of gefitinib alone to study its impact on tumor gene expression. Epidermal growth factor receptor (EGFR) protein expression, FISH and mutational status, and matrix metallopeptidase 11 (MMP11) protein expression were correlated with response and survival outcome.

RESULTS

The overall response rate to gefitinib alone was 9.7%. The survival outcome is as follows: median disease free 1.3 years, median survival time 2.4 years, 3-year disease free 42.9%, and 3-year overall survival 48.4%. EGFR FISH, protein expression, and mutational status did not predict for response nor survival outcome of patients. Although MMP11 overexpression did not predict for response, it predicted significantly for a poorer survival outcome.

CONCLUSIONS

Gefitinib can be combined safely with cisplatin/RT. More studies are needed to uncover predictive biomarkers of benefit to gefitinib.

Epithelial-mesenchymal-transition induced by EGFR activation interferes with cell migration and response to irradiation and cetuximab in head and neck cancer cells

BACKGROUND AND PURPOSE

The role of epithelial-mesenchymal transition (EMT) in the poor outcome of EGFR-overexpressing SCCHN was evaluated.

MATERIAL AND METHODS

SCCHN cell lines were characterized for their cell morphology and expression of EGFR and the EMT-associated factors E-cadherin, vimentin and Snail1. The migratory potential of cells was assessed in motility assays. Response to irradiation and cetuximab was determined using clonogenic survival assays.

RESULTS

High basal expression of E-cadherin but low to absent vimentin expression could be observed in all SCCHN cell lines. Although E-cadherin expression levels did not change after treatment with EGF we observed a significant change in cell morphology resembling EMT. SCCHN cells with high basal levels of Snail1 resulting from constitutive EGFR activation were characterized by mesenchymal-like morphology, elevated migratory potential, reduced sensitivity to irradiation and cetuximab but increased sensitivity to the combined treatment.

CONCLUSIONS

Autocrine activation of EGFR leading to EMT is associated with a metastatic phenotype and reduced sensitivity of SCCHN cells to single-modality treatment with cetuximab or irradiation. The potential of Snail1 as biomarker for selection of patients who will mostly benefit from a combination of cetuximab and radiotherapy has to be evaluated in future clinical studies.

Targeting fibroblast growth factor receptor 3 enhances radiosensitivity in human squamous cancer cells

Conventional therapies including radiation therapy cannot cure squamous cell carcinoma (SCC), and new treatments are clearly required. Our recent studies have shown that SCC cell lines exhibiting radioresistance show significant upregulation of the fibroblast growth factor receptor 3 (FGFR3) gene. We hypothesized that inhibiting FGFR3 would suppress tumor cell radioresistance and provide a new treatment approach for human SCCs. In the present study, we found that RNA interference-mediated FGFR3 depletion in HSC-2 cells, a radioresistant cell line, induced radiosensitivity and inhibited tumor growth. Use of an FGFR3 inhibitor (PD173074) obtained similar results with suppression of the autophosphorylation extracellular signal-regulated kinase pathway in HSC-2 cells and lung cancer cell lines. Moreover, the antitumor growth effect of the combination of PD173074 and radiation in vivo was also greater than that with either drug alone or radiation alone. Our results provided novel information on which to base further mechanistic study of radiosensitization by inhibiting FGFR3 in human SCC cells and for developing strategies to improve outcomes with concurrent radiotherapy.

Gefitinib in combination with oral topotecan and cyclophosphamide in relapsed neuroblastoma: pharmacological rationale and clinical response

AIM

Activity and toxiciy of gefitinib in combination with topotecan and cyclophosphamide (CPA) were evaluated in a case-series of relapsed neuroblastoma (NB) patients. The in vitro activity of the combination was also assessed.

PROCEDURE

Gefitinib (250 mg/day), topotecan (0.8 mg/m(2)/day), and CPA (50 mg/m(2)/day) (GTC) were administered orally for 14 consecutive days out of 28 days. Antitumor activity of gefitinib as single agent and in combination with either topotecan or CPA was assessed in a panel of NB cell lines.

RESULTS

Ninety-two courses were given in 10 patients. Grade 4 neutropenia was observed in 7/92 courses (8%) and grade 4 thrombocytopenia in 8/92 (9%). Two patients had a grade 2 liver toxicity, four a grade 1/2 skin toxicity, and two a grade 1/2 diarrhea. Dose reduction of topotecan and/or CPA was required in eight patients. After four courses, three patients were in partial response (PR) and four with a stable disease (SD), while three experienced a progressive disease (PD). Time to progression (TTP) was 9 months (range, 1-27). After a median follow-up of 16 months (range 5-54), seven patients are died of disease (DOD) and three alive with disease (AWD). All but one patient discontinued oral chemotherapy because of a PD, whilst one patient stopped chemotherapy after 27 months with a SD. In vitro, gefitinib was synergistic with topotecan and additive with CPA.

CONCLUSION

The GTC combination was well tolerated and the TTP was encouraging. These promising results, also supported by in vitro evidence, should be further confirmed in a phase II study.

Mechanism of lapatinib-mediated radiosensitization of breast cancer cells is primarily by inhibition of the Raf>MEK>ERK mitogen-activated protein kinase cascade and radiosensitization of lapatinib-resistant cells restored by direct inhibition of MEK

BACKGROUND AND PURPOSE

We recently showed that lapatinib, an EGFR/HER2 inhibitor, radiosensitized breast cancer cells of the basal and HER2+ subtypes. The purpose of this study was to identify the downstream signaling pathways responsible for lapatinib-mediated radiosensitization in breast cancer.

MATERIALS AND METHODS

Response of EGFR downstream signaling pathways was assessed by Western blot and clonogenic cell survival assays in breast tumor cells after irradiation (5Gy), lapatinib, CI-1040, or combined treatment.

RESULTS

In SUM102 cells, an EGFR+ basal breast cancer cell line, exposure to ionizing radiation elicited strong activation of ERK1/2 and JNK, which was blocked by lapatinib, and weak/no activation of p38, AKT or STAT3. Direct inhibition of MEK1 with CI-1040 resulted in 95% inhibition of surviving colonies when combined with radiation while inhibition of JNK with SP600125 had no effect. Lapatinib-mediated radiosensitization of SUM102 cells was completely abrogated with expression of constitutively active Raf. Treatment of lapatinib-resistant SUM185 cells with CI-1040 restored radiosensitization with 45% fewer surviving colonies when combined with radiation.

CONCLUSIONS

These data suggest that radiosensitization by lapatinib is mediated largely through inhibition of MEK/ERK and that direct inhibition of this pathway may provide an additional avenue of radiosensitization in EGFR+ or HER2+ breast cancers.

Receptor signaling as a regulatory mechanism of DNA repair

Radiotherapy plays a crucial role in the treatment of many malignancies; however, locoregional disease progression remains a critical problem. This has stimulated laboratory research into understanding the basis for tumor cell resistance to radiation and the development of strategies for overcoming such resistance. We know that some cell signaling pathways that respond to normal growth factors are abnormally activated in human cancer and that these pathways also invoke cell survival mechanisms that lead to resistance to radiation. For example, abnormal activation of the epidermal growth factor receptor (EGFR) promotes unregulated growth and is believed to contribute to clinical radiation resistance. Molecular blockade of EGFR signaling is an attractive strategy for enhancing the cytotoxic effects of radiotherapy and, as shown in numerous reports, the radiosensitizing effects of EGFR antagonists correlate with a suppression of the ability of the cells to repair radiation-induced DNA double strand breaks (DSBs). The molecular connection between the EGFR and its governance of DNA repair capacity appears to be mediated by one or more signaling pathways downstream of this receptor. The purpose of this review is to highlight what is currently known regarding EGFR signaling and the processes responsible for repairing radiation-induced DNA lesions that would explain the radiosensitizing effects of EGFR antagonists.

Pro-survival AKT and ERK signaling from EGFR and mutant EGFRvIII enhances DNA double-strand break repair in human glioma cells

The epidermal growth factor receptor (EGFR) is frequently dysregulated in malignant glioma that leads to increased resistance to cancer therapy. Upregulation of wild type or expression of mutant EGFR is associated with tumor radioresistance and poor clinical outcome. EGFR variant III (EGFRvIII) is the most common EGFR mutation in malignant glioma. Radioresistance is thought to be, at least in part, the result of a strong cytoprotective response fueled by signaling via AKT and ERK that is heightened by radiation in the clinical dose range. Several groups including ours have shown that this response may modulate DNA repair. Herein, we show that expression of EGFRvIII promoted gamma-H2AX foci resolution, a surrogate for double-strand break (DSB) repair, and thus enhanced DNA repair. Conversely, small molecule inhibitors targeting EGFR, MEK, and the expression of dominant-negative EGFR (EGFR-CD533) significantly reduced the resolution of gamma-H2AX foci. When homologous recombination repair (HRR) and non-homologous end joining (NHEJ) were specifically examined, we found that EGFRvIII stimulated and CD533 compromised HRR and NHEJ, respectively. Furthermore, NHEJ was blocked by inhibitors of AKT and ERK signaling pathways. Moreover, expression of EGFRvIII and CD533 increased and reduced, respectively, the formation of phospho-DNA-PKcs and -ATM repair foci, and RAD51 foci and expression levels, indicating that DSB repair is regulated at multiple levels. Altogether, signaling from EGFR and EGFRvIII promotes both HRR and NHEJ that is likely a contributing factor towards the radioresistance of malignant gliomas.

Basic evidence of molecular targeted therapy for oral cancer and salivary gland cancer

BACKGROUND

Recently, attention has been focused on molecular targeted cancer therapy in various tumors. Although there is no single consistent molecular target specific for oral squamous cell carcinoma (OSCC) and salivary gland cancer (SGC), there are a number of promising candidate proteins. The aim of this review is to introduce the basic evidences to support the molecular targeting for OSCC and SGC.

METHODS

We focused on the 4 molecules, epidermal growth factor receptor (EGFR), cyclooxygenase-2 (COX-2), peroxisome proliferator-activated receptor gamma (PPARgamma), and progesterone receptor, that are, respectively, associated with the proliferation and the differentiation of OSCC and SGC.

RESULTS

Gefitinib ("Iressa," ZD1839), a small molecule EGFR tyrosine kinase inhibitor, can inhibit the proliferation of OSCC cell lines in a dose- and time-dependent manner and lead to cell cycle arrest with accumulation of cells in the G1 phase, and a decrease of cells in S phase. The agent suppressed tumor metastasis in the animal model. Furthermore, a cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. While radiation alone did not significantly affect p38 mitogen-activated protein kinase and MAP kinase kinase (MEK)1/2 autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Gefitinib enhanced tumor radioresponsiveness by multiple mechanisms, including the growth inhibition and effects on DNA repair after exposure to radiation. Next, the level of COX-2 expression correlated inversely with increased tumor radiation sensitivity. Treatment with celecoxib, a COX-2 selective inhibitor, enhanced the radioresponsiveness of HSC-2 cells, which constitutively expressed COX-2. Another promising molecular target is the PPARgamma, which is a member of the nuclear receptor superfamily of ligand-activated transcription factors. Recent studies have demonstrated that PPARgamma ligands induce cellular differentiation and inhibit cell growth in carcinomas of various types. These data suggest that synthetic PPARgamma ligands may be useful for molecular targeting of oral cancer. Finally, the possibility of using molecular targeted therapy directed at hormone receptors in the treatment of advanced SGCs was described.

CONCLUSION

The basic data strongly suggested the possibility of tumor suppression by targeting these molecules. Studies of different targeted agents alone or with more conventional treatment modalities are needed to fully determine what role the targeted therapy will play in the management of patients with OSCC and SGC.

Clinical target promiscuity: lessons from ras molecular trials

Mutated ras has been identified in approximately 30% of human tumors, and dysregulation of ras function and signal transduction pathways is a critical step in tumorigenesis. Herein, we review the early data that supports the concept that the intrinsic radiosensitivity of tumor cells can be altered by oncogenic ras expression and that this impacts the PI3K-dependent signaling cascade. This ras-induced radioresistance can be reversed using prenyl transferase inhibitors (PTIs.). We discuss the effects of PTIs as a radiosensitizer in both in vivo and in vitro studies and show that PTIs can lead to increased radiosensitization in vivo through a variety of potential mechanisms that enhance radiation-induced cell kill. We critically evaluate the use of ras biomarkers in predicting the clinical response to PTIs that may explain the mixed results seen thus far in clinical trials using PTIs as a clinical radiosensitizer. We conclude that Ras-mediated radioresistance is the result of multiple intercommunicating pathways functioning against a complex genetic background and a solitary biomarker may not be adequate to predict for PTI-mediated radiosensitization. Nonetheless, our knowledge of the ras-signaling pathway has led to development and testing of specific therapies directed against PI3K-AKT signaling pathways as a future approach towards clinical radiosensitization.

The combination of epidermal growth factor receptor inhibitors with gemcitabine and radiation in pancreatic cancer

PURPOSE

Gemcitabine-radiotherapy is a standard treatment for locally advanced pancreatic cancer. Clinical data have shown that gemcitabine plus erlotinib is superior to gemcitabine alone for advanced pancreatic cancer. Therefore, we investigated the effects of the combination of epidermal growth factor receptor inhibitors with gemcitabine and radiation on a pancreatic cancer model.

EXPERIMENTAL DESIGN

EGFR signaling was analyzed by measuring phosphorylated EGFR (pEGFR(Y845, (Y1173)) and AKT (pAKT(S473)) protein levels in pancreatic cancer cell lines and tumors. The effects of scheduling on gemcitabine-mediated cytotoxicity and radiosensitization combined with erlotinib were determined by clonogenic survival. In vivo, the effects of cetuximab or erlotinib in combination with gemcitabine-radiation on the growth of BxPC-3 tumor xenografts were measured.

RESULTS

We found in vitro that gemcitabine induced phosphorylation of EGFR at Y845 and Y1173 that was blocked by erlotinib. Treatment of BxPC-3 cells with gemcitabine before erlotinib enhanced gemcitabine-mediated cytotoxicity without abrogating radiosensitization. In vivo, cetuximab or erlotinib in combination with gemcitabine-radiation inhibited growth compared with gemcitabine-radiation (time to tumor doubling: gemcitabine + radiation, 19 +/- 3 days; cetuximab + gemcitabine + radiation, 30 +/- 3 days; P < 0.05, erlotinib + gemcitabine + radiation 28 +/- 3 days; P < 0.1). Cetuximab or erlotinib in combination with gemcitabine-radiation resulted in significant inhibition of pEGFR(Y1173) and pAKT(S473) early in treatment, and pEGFR(Y845), pEGFR(Y1173), and pAKT(S473) by the end of treatment. This study shows a novel difference pEGFR(Y845) and pEGFR(Y1173) in response to EGFR inhibition.

CONCLUSIONS

These results show that the EGFR inhibitors cetuximab and erlotinib increase the efficacy of gemcitabine-radiation. This work supports the integration of EGFR inhibitors with gemcitabine-radiation in clinical trials for pancreatic cancer.

In vitro evaluation of the effects of gefitinib on the cytotoxic activity of selected anticancer agents in a panel of human endometrial cancer cell lines

PURPOSE

This study was conducted to determine the in vitro optimal combination of selected anticancer agents with gefitinib and evaluate its effect on the expression of correlative biological targets in the cell-signaling pathway. In addition, the effect of gefitinib on the expression of ATP-binding cassette (ABC) transport proteins was evaluated.

METHODS

Growth inhibition assays were conducted in six human endometrial cancer cell lines to evaluate the activity of selected anticancer agents with gefitinib compared to each alone. Enzyme linked immunosorbant assay (ELISA) assessed the presence of pEGFR in treated and untreated cells. Evaluation of the suppression of correlative biological targets in the cell-signaling pathway was completed by immunoblotting. RT-PCR was used to characterize the expression of MRP and ABC transport proteins.

RESULTS

This in vitro study gefitinib did not observe cytotoxic activity as a single agent. However, the activity of gefitinib as EGFR inhibitor was confirmed. The combination of gefitinib with paclitaxel and docetaxel exhibited improved in vitro cytotoxic activity compared to each antineoplastic agent alone. Suppression of pAKT and p27 in the human endometrial cancer cells treated with selected combinations of chemotherapeutic drugs and gefitinib was observed.

CONCLUSION

These data suggest that EGFRinhibitors, such as gefitinib, have the potential to modulate common mechanisms of drug resistance and may have a role in optimizing antineoplastic regimens for the treatment of recurrent endometrial cancer. This may represent a promising option for this class of agents in the treatment of endometrial cancer.

Gefitinib radiosensitizes non-small cell lung cancer cells by suppressing cellular DNA repair capacity

PURPOSE

Overexpression of the epidermal growth factor receptor (EGFR) promotes unregulated growth, inhibits apoptosis, and likely contributes to clinical radiation resistance of non-small cell lung cancer (NSCLC). Molecular blockade of EGFR signaling is an attractive therapeutic strategy for enhancing the cytotoxic effects of radiotherapy that is currently under investigation in preclinical and clinical studies. In the present study, we have investigated the mechanism by which gefitinib, a selective EGFR tyrosine kinase inhibitor, restores the radiosensitivity of NSCLC cells.

EXPERIMENTAL DESIGN

Two NSCLC cell lines, A549 and H1299, were treated with 1 micromol/L gefitinib for 24 h before irradiation and then tested for clonogenic survival and capacity for repairing DNA double strand breaks (DSB). Four different repair assays were used: host cell reactivation, detection of gamma-H2AX and pNBS1 repair foci using immunofluorescence microscopy, the neutral comet assay, and pulsed-field gel electrophoresis.

RESULTS

In clonogenic survival experiments, gefitinib had significant radiosensitizing effects on both cell lines. Results from all four DNA damage repair analyses in cultured A549 and H1299 cells showed that gefitinib had a strong inhibitory effect on the repair of DSBs after ionizing radiation. The presence of DSBs was especially prolonged during the first 2 h of repair compared with controls. Immunoblot analysis of selected repair proteins indicated that pNBS1 activation was prolonged by gefitinib correlating with its effect on pNBS1-labeled repair foci.

CONCLUSIONS

Overall, we conclude that gefitinib enhances the radioresponse of NSCLC cells by suppressing cellular DNA repair capacity, thereby prolonging the presence of radiation-induced DSBs.

The emerging role of cetuximab in head and neck cancer: a 2007 perspective

The integration of targeted therapies into clinical practice constitutes the paradigm of oncology treatment in the current era. Cetuximab, a recombinant human/mouse chimeric epidermal growth factor (EGFR) monoclonal antibody is a targeted agent that has seen expanding indication in recent years. Originally approved for colorectal cancer, its role in the treatment of squamous cell carcinoma of the head and neck has augmented treatment options for patients who are refractory to or cannot tolerate platinum. This article will review the science underlying cetuximab, data supporting its use in patients with locally advanced and recurrent/metastatic disease, common toxicities of therapy, and the integration of this treatment with radiation therapy.

Prolonged response to oral gefitinib, cyclophosphamide, and topotecan in heavily pretreated relapsed stage 4 neuroblastoma: a case report

A girl with metastatic neuroblastoma diagnosed at 4 years of age experienced an early disseminated relapse after high-dose chemotherapy. After reinduction, compassionate treatment with gefitinib (250 mg/d fixed dose) with oral topotecan (0.8 mg/m(2)/d) and cyclophosphamide (50 mg/m(2)/d) for 14 consecutive days, each course repeated every 28 days, was administered. Complete marrow clearance and metaiodobenzylguanidine response were achieved after 4 courses. After the first course, topotecan and cyclophosphamide were reduced by 25% for grade 4 hematologic toxicity. Subsequent courses were well tolerated. The girl remained progression free for 27 months. This combination may represent a viable therapeutic option and deserves further evaluation in resistant neuroblastoma.

Phase I Trial of Gefitinib in Combination With Radiation or Chemoradiation for Patients With Locally Advanced Squamous Cell Head and Neck Cancer

Purpose

To establish the safety and toxicity profile of daily gefitinib with radiation alone or with concurrent chemoradiotherapy in previously untreated patients with locally advanced squamous cell head and neck cancer (LAHNC).

Patients and Methods

Patients with intermediate-stage LAHNC were treated with concomitant boost radiation (RT) alone with escalating doses of daily gefitinib (250 or 500 mg; cohort I). Once a safety profile was determined with RT alone, patients with high-risk disease were then treated with daily gefitinib (250 or 500 mg), weekly cisplatin (CDDP; 30 mg/m2), and once-daily RT (cohort II). Patients also received post-RT gefitinib at 250 mg daily for a period of up to 2 years.

Results

Twenty-three patients were enrolled and assessable for toxicity. No dose-limiting toxicities (DLTs) were observed in patients treated in cohort I at either 250 or 500 mg of gefitinib daily with concomitant boost RT to 72 Gy. In patients receiving chemoradiotherapy and gefitinib (cohort II), DLTs included one grade 4 diarrhea and one grade 4 neutropenic fever. Fifteen patients started maintenance gefitinib, and eight (53%) experienced grade 1 to 2 acne-like skin rash and diarrhea, but no grade 3 or 4 toxicity occurred.

Conclusion

Gefitinib (250 or 500 mg daily) was well tolerated with concomitant boost RT or concurrent chemoradiotherapy with weekly CDDP. Protracted administration of gefitinib for up to 2 years at 250 mg daily was also tolerated well.

Stimulated PI3K-AKT signaling mediated through ligand or radiation-induced EGFR depends indirectly, but not directly, on constitutive K-Ras activity

Previous results showed an inducible radiation sensitivity selectively observable for K-RAS-mutated cell lines as a function of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor blockade of phosphatidylinositol 3-kinase (PI3K)-AKT signaling. Therefore, the role of K-Ras activity for a direct (i.e., through activation of PI3K by K-Ras) or an indirect stimulation of PI3K-AKT signaling (through K-Ras activity-dependent EGFR ligand production) was investigated by means of small interfering RNA and inhibitor approaches as well as ELISA measurements of EGFR ligand production. K-RASmt tumor cells presented a constitutively activated extracellular signal-regulated kinase-1/2 signaling, resulting in enhanced production and secretion of the EGFR ligand amphiregulin (AREG). Medium supernatants conditioned by K-RASmt tumor cells equally efficiently stimulated EGFR signaling into the PI3K-AKT and mitogen-activated protein kinase pathways. Knocking down K-Ras expression by specific small interfering RNA markedly affected autocrine production of AREG, but not PI3K-AKT signaling, after treatment of K-RAS-mutated or wild-type cells with EGFR ligands or exposure to ionizing radiation. These results indicate that PI3K-mediated activation of AKT in K-RASmt human tumor cells as a function of EGFR ligand or radiation stimulus is independent of a direct function of K-Ras enzyme activity but depends on a K-Ras-mediated enhanced production of EGFR ligands (i.e., most likely AREG) through up-regulated extracellular signal-regulated kinase-1/2 signaling. The data provide new differential insight into the importance of K-RAS mutation in the context of PI3K-AKT-mediated radioresistance of EGFR-overexpressing or EGFR-mutated tumors.

Exacerbated radiodermatitis and bilateral subdural hemorrhage after whole brain irradiation combined with epidermal growth factor receptor tyrosine kinase inhibitors for brain metastases in lung cancer

A 57-year-old male developed an adenocarcinoma lung cancer in November 2003. He received the full course chemotherapy but without a significant regression. The targeted therapy gefitinib was prescribed 2 years after diagnosis, producing a very good partial response. However, brain metastasis was diagnosed. A whole brain irradiation was performed for 37.5Gy with a fraction size of 2.5Gy and gefitinib was replaced with erlotinib on the 5th day after radiation therapy commenced for disease progressing. Unexpectedly, the patient developed a severe skin reaction in the region exposed to the radiation field, and a bilateral subdural hemorrhage, following radiation therapy. The reaction was thought to be triggered by the combination of radiation and epidermal growth factor receptor tyrosine kinase inhibitors, which may be responsible for hypersensitizing the radiation response in normal tissue in the unique individual.

EGFR-targeted anti-cancer drugs in radiotherapy: preclinical evaluation of mechanisms

Preclinical and clinical results indicate that the EGFR can mediate radioresistance in different solid human tumours. Combination of radiotherapy and EGFR inhibitors can improve local tumour control compared to irradiation alone and has been introduced into clinical radiotherapy practice. So far several mechanisms have been identified in preclinical studies to contribute to improved local tumour control after radiation combined with EGFR inhibitors. These include direct kill of cancer stem cells by EGFR inhibitors, cellular radiosensitization through modified signal transduction, inhibition of repair of DNA damage, reduced repopulation and improved reoxygenation during fractionated radiotherapy. Effects and mechanisms may differ for different classes of EGFR inhibitors, for different tumours and for normal tissues. The mechanisms underlying this heterogeneity are currently poorly understood, and predictive assays are not available yet. Importantly, mechanisms and predictors for the combined effects of radiation with EGFR inhibitors appear to be considerably different to those for application of EGFR inhibitors alone or in combination with chemotherapy. Therefore to further evaluate the efficacy and mechanisms of EGFR-inhibition in combined treatments, radiotherapy-specific preclinical research strategies, which include in vivo experiments using local tumour control as an endpoint, as well as animal studies on normal tissue toxicity are needed.

Pharmacodiagnostic evaluation of EGFR expression in oral squamous cell carcinoma

OBJECTIVE

To determine epidermal growth factor receptor (EGFR) expression in oral squamous cell carcinomas (OSCC), and its possible relationships with clinical findings, histological findings, disease course and prognosis.

MATERIALS AND METHODS

Surgical specimens of 47 OSCCs were studied immunohistochemically for detection of EGFR using a standardized immunohistochemical detection system (EGFR PharmaDx kit). Statistical analysis was used to investigate possible relationships between EGFR expression and clinical findings, histological findings, cell proliferation (MIB1 labelling index), disease course and patient survival.

RESULTS

Epidermal growth factor receptor expression was absent or weak in 12 cases (25.5%) and moderate or intense in 35 cases (74.5%). However, EGFR expression did not show statistically significant associations with any of the clinical, histological, biological or prognostic variables considered.

CONCLUSION

First, despite previous suggestions that EGFR is a useful indicator of biological tumour behaviour, the present results suggest that EGFR is not a useful indicator of prognosis in OSCC. Secondly, the high prevalence of EGFR overexpression suggests that the possibility of anti-EGFR therapy in OSCC merits further investigation.

Identification of a novel EGF-sensitive cell cycle checkpoint

The site of action of growth factors on mammalian cell cycle has been assigned to the boundary between the G1 and S phases. We show here that Epidermal Growth Factor (EGF) is also required for mitosis. BaF/3 cells expressing the EGFR (BaF/wtEGFR) synthesize DNA in response to EGF, but arrest in S-phase. We have generated a cell line (BaF/ERX) with defective downregulation of the EGFR and sustained activation of EGFR signalling pathways: these cells undergo mitosis in an EGF-dependent manner. The transit of BaF/ERX cells through G2/M strictly requires activation of EGFR and is abolished by AG1478. This phenotype is mimicked by co-expression of ErbB2 in BaF/wtEGFR cells, and abolished by inhibition of the EGFR kinase, suggesting that sustained signalling of the EGFR, through impaired downregulation of the EGFR or heterodimerization, is required for completion of the cycle. We have confirmed the role of EGFR signalling in the G2/M phase of the cell cycle using a human tumor cell line which overexpresses the EGFR and is dependent on EGFR signalling for growth. These findings unmask an EGF-sensitive checkpoint, helping to understand the link between sustained EGFR signalling, proliferation and the acquisition of a radioresistant phenotype in cancer cells.

Les thérapeutiques ciblées en association avec la radiothérapie dans le cancer bronchique

Targeted therapies are now more often used in lung cancer. Inhibitors of EGFR and of angiogenesis have demonstrated a certain activity in this disease. Some experimental in vitro or in vivo studies are in favour of combined targeted therapies and radiation. For example, additive or supra-additive effects have been shown when inhibitors of the EGFR tyrosine kinase were given with radiation. In advanced lung cancer, the combination of bevacizumab with chemotherapy was demonstrated to produce better survival outcomes. But a high rate of fatal hemoptysis was reported with this drug, particularly for central and squamous tumors. This could be a limitation for its use in combination with radiation. Drugs with multiple targets are becoming available; their association with radiation seems to be promising.

Integration of EGFR inhibitors with radiochemotherapy

Laboratory studies that led to the development of epidermal growth factor receptor (EGFR) inhibitors indicated that such inhibitors would be effective when given to patients with tumours that are driven by activated EGFR. However, initial clinical studies have shown modest responses to EGFR inhibitors when used alone, and it has not yet been possible to clearly identify which tumours will respond to this therapy. As a result, EGFR inhibitors are now used in combination with radiation therapy, chemotherapy and, more recently, with concurrent radiochemotherapy. In general, these clinical trials have been designed without much preclinical data. What do we need to know to make these combinations successful in the clinic?