Cetuximab, a monoclonal antibody targeting the epidermal growth factor receptor, in combination with gemcitabine for advanced pancreatic cancer: a multicenter phase II Trial

Challenges in the treatment of gastrointestinal tumours

In the last 20 years there have been many breakthroughs in the treatment of gastrointestinal tumours. In this review we have considered the three most important subgroups of gastrointestinal tumours (colorectal, gastric and pancreatic cancer), focusing on the state-of-the-art treatments.

Specific peptide ligand for Grb7 signal transduction protein and pancreatic cancer metastasis

BACKGROUND

Pancreatic cancer is one of the most aggressive malignancies, with high rates of invasion and metastasis and with generally poor prognosis. We previously found that metastasis was strongly associated with the expression of growth factor receptor-bound protein 7 (Grb7), which contains a Src homology 2 (SH2) domain. In this study, we evaluated Grb7 protein as a molecular target of therapy for metastatic pancreatic cancer.

METHODS

Grb7 protein expression was measured by immunohistochemistry in 36 human pancreatic cancer specimens and adjacent normal pancreatic tissue. We synthesized a nonphosphorylated peptide inhibitor that binds specifically to the SH2 domain of Grb7. Intracellular signaling was assessed by immunoprecipitation and immunoblot assays in cultured human pancreatic cancer cells. Cell migration was measured with a modified Boyden chamber method. Peritoneal metastasis of the pancreatic cancer cells was measured with a mouse model. All statistical tests were two-sided.

RESULTS

We found that 22 (61%) of 36 pancreatic cancer specimens had higher levels of Grb7 protein than their corresponding normal pancreatic tissue specimens. Grb7 expression was statistically significantly different between specimens from patients without lymph node metastasis (stage N0; two of the 10 patients) and patients with lymph node metastasis (stages N1 + N2; 20 of the 26 patients) (P = .006). The Grb7 peptide inhibitor selectively blocked the interaction between Grb7 and focal adhesion kinase and blocked the phosphorylation of Grb7 protein. In vivo Grb7 peptide inhibitor statistically significantly attenuated cell migration (for control peptide, 87.5 cells migrated, 95% confidence interval [CI] = 82.6 to 92.4 cells; for Grb7 peptide, 5.7 cells migrated, 95% CI = 2.3 to 9.0 cells; P < .001) and peritoneal metastasis of the pancreatic cancer cells in a mouse model, as assessed by the number of nodules (control = 72.6 nodules, 95% CI = 55.8 to 89.4 nodules; and for Grb7 peptide = 3.2 nodules, 95% CI = 1.6 to 4.8 nodules; P < .001, t test) and their weight (control = 4.13 g, 95% CI = 3.40 to 4.86 g; Grb7 peptide = 0.19 g, 95% CI = 0.06 to 0.32 g; P < .001, t test).

CONCLUSIONS

The Grb7 peptide inhibitor appears to be a promising molecularly targeted therapeutic agent against metastatic pancreatic cancer.

Chemotherapy for advanced pancreatic cancer

Single-agent gemcitabine was established as standard treatment for advanced pancreatic cancer after a superior clinical benefit response was demonstrated in a randomized study comparing it to 5-fluorouracil (FU). Until recently, many subsequent randomized trials of newer, often gemcitabine-based combinations have not been able to show improved survival over gemcitabine. Combination gemcitabine and capecitabine is likely to become the preferred standard treatment, at least in the UK, on the basis of the positive interim results of the UK National Cancer Research Institute (NCRI) randomized study of chemotherapy with this combination. At present, there is no standard second-line treatment for patients who have become refractory to gemcitabine, although a recently reported study has suggested that oxaliplatin with FU and leucovorin is superior to best supportive care in these patients. This article will review and discuss the clinical trials of chemotherapy for this disease, including the more recent trials, which have included the novel targeted agents.

What's new in pancreatic cancer treatment pipeline?

There is still a substantial need for the development of new treatments for patients with pancreatic cancer. In this chapter, we will document that there is quite a bit of an increase in research activity with development in two major areas including (1) agents in the pipeline which already have hints of antitumor activity in patients with pancreatic cancer (therapeutic monoclonal antibodies and vaccines as well as more conventional cytotoxics), and; (2) agents in the pipeline which have just started (or will soon start) in clinical trial. These agents range from a gene-therapy approach to radiation enhancement to inhibitors of protein with increased expression in the very hypoxic pancreatic cancer tissue, to new monoclonal antibodies. With the level of investigational activity in pancreatic cancer it is very likely that several new therapeutic approaches to the disease will be forthcoming.

Epidermal Growth Factor Receptor (EGFR) Inhibitors in Gastrointestinal Cancer

Gastrointestinal (GI) cancer continues to be a leading cause of cancer morbidity and mortality worldwide. Over the past decade the treatment options for patients with GI cancers have increased with the advent of newer combination chemotherapy regimes. Despite these clinical advances, new strategies are warranted in order to improve the efficacy as well as the safety. New molecular targets have provided novel opportunities in the treatment of GI cancer. One of the most advanced new approaches to date is the use of targeted inhibitors of the epidermal growth factor receptor (EGFR). In this review we describe the current status of therapeutic strategies based on EGFR inhibitors in the treatment of GI cancer.

Kidney cancer: identification of novel targets for therapy

Kidney cancer, although relatively rare when compared to other malignancies, occurs not uncommonly in patients with renal disease and is often discovered incidentally during the initial nephrologic work-up, or by the savvy clinician who is familiar with the paraneoplastic signs. While surgical approaches are generally curative when the disease is confined to the kidney, one-third of the cases that present in the metastatic form and require conventional medical therapy are associated with a truly dismal patient survival rate. In light of the emerging knowledge of the molecular mechanisms of kidney cancer oncogenesis, several novel and promising therapeutic approaches are emerging. In this review, we summarize the current state of kidney cancer diagnosis and therapy, as well as some of the novel treatments that capitalize on those newly elucidated molecular pathways that are deranged in this disease.

Synergistic effects of gemcitabine and gefitinib in the treatment of head and neck carcinoma

Although the combination of gemcitabine and radiation produces a high frequency of complete responses in the treatment of locally advanced head and neck cancer, substantial toxicity suggests that an improvement in the therapeutic index is required. The purpose of this study was to determine if gefitinib could improve the efficacy of gemcitabine and if drug schedule is important. We hypothesized that gemcitabine followed by gefitinib would be superior to the opposite order because of both cell cycle and growth factor signaling interactions. Using UMSCC-1 cells in vitro, we confirmed that gefitinib arrested cells in G(1) and suppressed phospho-epidermal growth factor receptor (p(Y845)EGFR) and that gemcitabine arrested cells in S phase and stimulated p(Y845)EGFR. The schedule of gemcitabine followed by gefitinib caused arrest of cells in S phase. Gefitinib suppressed gemcitabine-mediated p(Y845)EGFR stimulation. This schedule caused decreased p(S473)AKT, increased poly(ADP-ribose) polymerase cleavage, and increased apoptosis compared with gemcitabine alone. The schedule of gefitinib followed by gemcitabine also caused suppression of p(Y845)EGFR but arrested cells in G(1). This schedule in which gefitinib was used first was associated with stable levels of p(S473)AKT and minimal poly(ADP-ribose) polymerase cleavage and apoptosis. These results were reflected in experiments in nude mice bearing UMSCC-1 xenografts, in which there was greater tumor regression and apoptosis when animals received gemcitabine followed by gefitinib during the first week of therapy. These findings suggest that the schedule of gemcitabine followed by gefitinib may increase the therapeutic index over gemcitabine alone and, combined with clinical data, encourage exploration of combination of gemcitabine, EGFR inhibitors, and radiation.

Treatment of familial pancreatic cancer and its precursors

Approximately 10% of pancreatic cancers are believed to have a familial basis. The familial aggregation of pancreatic cancers provides a unique opportunity to prevent the development of pancreatic cancer, to identify and treat precancerous lesions of the pancreas, and to advance our understanding of the genetic basis for the development of all forms of pancreatic cancer. After appropriate genetic counseling, individuals with a strong family history of pancreatic cancer can now be tested for inherited genetic alterations that are known to increase the risk of pancreatic cancer. These include germline BRCA2, STK11/LKB1, p16/CDKN2A and PRSS1 gene mutations. Individuals with one of these inherited genetic alterations and individuals with a strong family history of pancreatic cancer can be counseled on smoking cessation and possible dietary modifications. Selected individuals, even if they are asymptomatic, can be screened using a combination of endoscopic ultrasound and multidetector computed tomography. Patients found to have a mass lesion in the pancreas would then be candidates for surgical resection. The resection of noninvasive precancers will cure these lesions before they have the opportunity to spread and metastasize. Even with the best early detection efforts, some patients will still be diagnosed with an invasive cancer. Surgical resection of invasive pancreatic cancer is proven to be safe and can provide long-term survival in patients with small, node-negative, and margin-negative cancers. Chemotherapy and radiation therapy are effective in some patients with invasive pancreatic cancer, but these therapies do not usually result in long-term cures. Individuals with a family history of pancreatic cancer may also choose to join a research study such as the National Familial Pancreas Tumor Registry.

Fixed dose-rate infusion of gemcitabine in combination with cisplatin and UFT in advanced carcinoma of the pancreas

BACKGROUND

Gemcitabine is currently considered the standard treatment for advanced pancreatic cancer (APC). Cisplatin and a fluoropyrimidine have some activity in the treatment of this cancer. The aim of this trial is to evaluate the efficacy and toxicity of a fixed dose-rate infusion of gemcitabine associated with cisplatin and UFT in patients with APC.

PATIENTS AND METHODS

Forty-six chemotherapy-naïve patients with APC that was either unresectable or metastatic were included in this phase II study. All of them had Karnofsky performance status > or =50 and unidimensionally measurable disease. Treatment consisted of gemcitabine 1,200 mg/m2 given as a 120-min infusion weekly for three consecutive weeks, cisplatin 50 mg/m2 on day 1 and oral UFT 400 mg/m2/day (in two to three daily doses) on days 1 to 21; cycles of treatment were given every 28 days.

RESULTS

A total of 208 cycles of chemotherapy were given with a median of 4 per patient. Fourteen patients (30%) achieved partial responses (95% CI 19-48%) and 17 (37%) had stable disease. The median time to progression was 5 months, and the median overall survival 9 months. Nineteen patients (49%; 95% CI 32-64%) had a clinical benefit response. Grade 3-4 WHO toxicities were as follows: neutropaenia in 26 patients (57%), with 5 cases of febrile neutropaenia (11%), thrombocytopaenia in 15 (33%), anaemia in six (13%), diarrhoea in 5 (11%), asthenia in 2 (4%) and mucositis in 1 (2%). Seven patients required hospitalisation for treatment-related complications.

CONCLUSION

A fixed dose-rate infusion of gemcitabine associated with cisplatin and UFT is active in patients with APC, though at the cost of considerable toxicity.

Neoadjuvant chemoradiation in patients with pancreatic adenocarcinoma

In spite of the high mortality in pancreatic cancer, significant progress is being made. This review discusses multimodality therapy for patients with pancreatic cancer. Surgical therapy currently offers the only potential monomodal cure for pancreatic adenocarcinoma. However, only 10-20% of patients present with tumors that are amenable to resection, and even after resection of localized cancers, long-term survival is rare. The addition of chemoradiation therapy significantly increases median survival. To achieve long-term success in treating this disease it is therefore increasingly important to identify effective neoadjuvant/adjuvant multimodality therapies. Preoperative chemoradiation for potentially resectable pancreatic cancer has the following advantages: (1) neoadjuvant treatment would eliminate the delay of adjuvant treatment due to postoperative complications; (2) neoadjuvant treatment could avoid unnecessary surgery for patients with metastatic disease evident on restaging after neoadjuvant therapy; (3) down-staging after neoadjuvant therapy may increase the likelihood of negative surgical margins; and (4) neoadjuvant treatment could prevent peritoneal tumor cell implantation and dissemination caused during surgery. This review systematically summarizes the current status, controversies, and prospects of neoadjuvant treatment of pancreatic cancer.

Cytotoxic Chemotherapy for Pancreatic Cancer

Chemotherapy remains the mainstay of treatment for pancreatic cancer as most patients present with advanced disease, which precludes locoregional treatment. However, the efficacy of chemotherapy is limited. Gemcitabine is the only agent that improves symptoms and confers a modest survival advantage. Many combination therapy regimens have been studied in phase II settings. Eleven randomised phase III trials have been conducted to compare gemcitabine-containing regimens with gemcitabine monotherapy since gemcitabine became available clinically. The combination of gemcitabine plus capecitabine has demonstrated a survival advantage over gemcitabine, whereas gemcitabine plus oxaliplatin and gemcitabine plus cisplatin have shown improved progression-free survival or time to tumour progression but failed to demonstrate a survival advantage over gemcitabine. The search for effective therapy for advanced pancreatic cancer continues. Gemcitabine in combination with cytotoxic agents or molecular targeted agents hold promise.

Consensus report of the International Society of Gastrointestinal Oncology on therapeutic progress in advanced pancreatic cancer

Since 1997, when gemcitabine showed superior clinical benefit to single-agent 5-fluorouracil, it has remained the standard of care for the treatment of advanced pancreatic cancer. Numerous new agents, both cytotoxic and targeted, have been tested against this standard. Some trials showed improved response rates or progression free survival, but there was no clear improvement in survival. For the current report, those trial results were reviewed in depth for methodology, endpoints, and study characteristics. More recent studies have shown progress. Studies with combinations of gemcitabine and capecitabine and with the epidermal growth factor receptor antagoinist, erlotinib, have demonstrated survival benefits. Currently, studies of combinations with oxaliplatin, bevacizumab, and cetuximab are ongoing. Other targeted therapies also are considered for future clinical trials. Based on a comprehensive review of past trials, a consensus on endpoints in the treatment of pancreatic cancer and an approach to new trials is presented.

Expression and differential signaling of heregulins in pancreatic cancer cells

The EGF family of ligands and receptors plays an important role in the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) and contributes to its aggressiveness. A number of molecular approaches have been developed to block these pathways, and studies have already proven the clinical benefit of this concept in PDAC. In the present study, we sought to determine the potential role of heregulins (HRGs), a family of EGF-like growth factors, in PDAC. Quantitative RT-PCR analysis revealed that HRGs as well as its signaling ErbB receptors were present in 4 of 4 human pancreatic cancer cell lines (PCCL). HRG-beta1 stimulated the growth of 3 of 4 PCCL, whereas HRG-alpha1 inhibited cell growth in 3 of 4 cell lines. Responses towards HRGs could in part be predicted by ErbB2 and ErbB3 expression levels. HRGs induced phosphorylation of different ErbB receptors as well as activation of MAPK, p38MAPK, JNK and PI3K in a cell- and ligand-specific manner. In vivo, HRG was upregulated in pancreatic cancer tissues and localized predominantly in the cancer cells. High HRG-beta levels but not HRG-alpha levels were associated with decreased patient survival. In conclusion, HRG is expressed by pancreatic cancer cells and influences pancreatic cancer cell growth and patient survival.

Molecular evidence for increased antitumor activity of gemcitabine by genistein in vitro and in vivo using an orthotopic model of pancreatic cancer

Soy isoflavone genistein exhibits growth inhibitory activity against human pancreatic cancer cell lines. We previously reported the potential of genistein to augment chemotherapeutic response of pancreatic cancer cells in vitro. In the present study, we investigated whether genistein pretreatment could be used as a novel strategy for gemcitabine-induced killing in vitro and enhanced antitumor activity in vivo using an orthotopic tumor model. We conducted our studies using paired isogenic human pancreatic cancer cell line with differences in metastatic behavior (COLO 357 and L3.6pl). In vitro studies were done to measure growth inhibition and degree of apoptotic cell death induced by either genistein alone, gemcitabine alone, or genistein followed by gemcitabine. Our results show that pretreatment of cells with genistein for 24 hours followed by gemcitabine resulted in 60% to 80% growth inhibition compared with 25% to 30% when gemcitabine was used alone. The overall growth inhibition was directly correlated with apoptotic cell death irrespective of the metastatic potential of cells. Several genes that are known to inhibit apoptosis and contribute to chemoresistance such as nuclear factor-kappaB (NF-kappaB) and Akt were assessed to investigate the basis for the observed chemosensitizing effects of genistein. Genistein potentiated the gemcitabine-induced killing by down-regulation of NF-kappaB and Akt. In contrast, Akt and NF-kappaB were found to be up-regulated when pancreatic cancer cells were exposed to gemcitabine alone, suggesting the potential mechanism of acquired chemoresistance. In addition to in vitro results, we show here for the first time, that genistein in combination with gemcitabine is much more effective as an antitumor agent compared with either agent alone in our orthotopic tumor model. But most importantly, our data also showed that a specific target, such as NF-kappaB, was inactivated in genistein-treated animal tumors and that gemcitabine-induced activation of NF-kappaB was completely inhibited in animal tumors treated with genistein and gemcitabine. These results provide strong molecular in vivo evidence in support of our hypothesis that inactivation of NF-kappaB signaling pathway by genistein could also abrogate gemcitabine-induced activation of NF-kappaB resulting in the chemosensitization of pancreatic tumors to gemcitabine, which is likely to be an important and novel strategy for the treatment of pancreatic cancer.

Epidermal growth factor inhibition in solid tumours

The epidermal growth factor receptor (EGFR) plays an important role in the carcinogenesis of many human malignancies and is therefore an attractive target against which anticancer therapy may be effective. At present, there are two ways in which this may be achieved clinically: antibodies against EGFR and inhibitors of the EGFR tyrosine kinase. This review describes presently approved agents cetuximab (monoclonal EGFR antibody), gefitinib and erlotinib (EGFR tyrosine kinase inhibitors) in detail. Efficacy data for these agents in various human malignancies is presented. Various other agents that are in the early stages of development at present have also been mentioned.

Phase II trial of induction gemcitabine/CPT-11 followed by a twice-weekly infusion of gemcitabine and concurrent external beam radiation for the treatment of locally advanced pancreatic cancer

PURPOSE

This phase II trial of induction irinotecan/gemcitabine followed by twice-weekly gemcitabine and upper abdominal radiation was initiated to determine the activity of this regimen in patients with unresectable pancreatic cancer.

METHODS

Patients with locally advanced, nonmetastatic adenocarcinoma of the pancreas received 2 cycles of induction irinotecan (100 mg/m2 IV) and gemcitabine (1000 mg/2 IV) on days 1 and 8 of each 3-week cycle. Following the induction, patients without disease progression received gemcitabine administered twice weekly (40 mg/m2/day) for 5 weeks concurrent with upper abdominal radiation (50.4 Gy over 5.5 weeks).

RESULTS

From April 2000 to August 2003, 20 patients were entered into this study, 17 of whom were evaluable for treatment response. Characteristics included a median age of 67 years (range, 44-87 years) and 14 men (70%). Grades III and IV hematologic toxicity occurred in 25% and 5% of patients respectively and was primarily thrombocytopenia. No grade IV gastrointestinal toxicities or deaths due to therapy were observed. All therapy was completed in 8 patients, 7 patients were removed due to progression, 2 due to toxicity, 2 refused further treatment, and 1 was removed per the treating physician. The median time to progression and median survival was 5.1 months (95% CI, 3.2-6.7) and 8.8 months (95% CI, 6.4-10.1) respectively. Four patients (20%) were alive at 12 and 18 months.

CONCLUSION

Induction irinotecan/gemcitabine followed by twice-weekly gemcitabine and upper abdominal radiation is feasible in patients with locally advanced pancreatic cancer. This regimen, however, has only modest activity and should not be explored further.

Simultaneous inhibition of EGFR, VEGFR, and platelet-derived growth factor receptor signaling combined with gemcitabine produces therapy of human pancreatic carcinoma and prolongs survival in an orthotopic nude mouse model

Although gemcitabine has been approved as the first-line chemotherapeutic reagent for pancreatic cancer, its response rate is low and average survival duration is still only marginal. Because epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR) modulate tumor progression, we hypothesized that inhibition of phosphorylation of all three on tumor cells, tumor-associated endothelial cells, and stroma cells would improve the treatment efficacy of gemcitabine in an orthotopic pancreatic tumor model in nude mice and prolong survival. We implanted L3.6pl, a human pancreatic cancer cell, in the pancreas of nude mice. We found that tumor-associated endothelial cells in this model highly expressed phosphorylated EGFR, VEGFR, and PDGFR. Oral administration of AEE788, a dual tyrosine kinase inhibitor against EGFR and VEGFR, decreased phosphorylation of EGFR and VEGFR. PDGFR phosphorylation was inhibited by STI571. Although i.p. injection of gemcitabine did not inhibit tumor growth, its combination with AEE788 and STI571 produced >80% inhibition of tumor growth and prolonged survival in parallel with increases in number of tumor cells and tumor-associated endothelial cell apoptosis, decreased microvascular density, decreased proliferation rate, and prolonged survival. STI571 treatment also decreased pericyte coverage on tumor-associated endothelial cells. Thus, inhibiting phosphorylation of EGFR, VEGFR, and PDGFR in combination with gemcitabine enhanced the efficacy of gemcitabine, resulting in inhibition of experimental human pancreatic cancer growth and significant prolongation of survival.

Recent advances on the molecular mechanisms involved in pancreatic cancer progression and therapies

This review describes the recent advances in the molecular events involved in pancreatic cancer initiation, progression, and metastasis. Additionally, the importance of deregulated cellular signaling elements as potential targets for developing novel therapeutic strategies against incurable forms of pancreatic cancer is reported. The emphasis is on the critical functions gained by numerous growth factors and their receptors, such as epidermal growth factor receptor, hedgehog signaling, and proangiogenic agents such as vascular endothelial factor and interleukin-8 for the sustained growth, survival, and metastasis of pancreatic cancer cells. The molecular mechanisms associated with antitumoral properties and the clinical benefits of gemcitabine alone or in combination with other cytotoxic agents for the treatment of pancreatic cancer are discussed.

Current Status of Small-Molecule Tyrosine Kinase Inhibitors Targeting Epidermal Growth Factor Receptor in Colorectal Cancer

The epidermal growth factor receptor (EGFR) is expressed in the majority of colorectal cancers (CRCs) and is associated with poor clinical outcome. Ample evidence suggests that inhibition of this pathway by monoclonal antibodies directed against EGFR leads to antitumor activity in CRC. Small-molecule tyrosine kinase inhibitors (TKIs) provide distinct advantages over monoclonal antibodies by virtue of lower production costs, ease of oral administration, and ability to target multiple cellular survival pathways. Despite theoretical advantages, multiple early-phase trials of EGFR TKIs fail to demonstrate single-agent activity in CRC. However, the unusually high response rates observed when gefitinib, an EGFR TKI, is combined with chemotherapy for patients with metastatic CRC suggest a possible synergistic effect. This effect is not seen in non-small-cell lung cancer (NSCLC), for which larger phase III trials have been conducted. The differences between NSCLC and CRC with respect to EGFR expression and mutation status do not completely explain this dichotomy, and further investigation into the pharmacogenomics of EGFR tyrosine kinase inhibition in CRC is under way. Significant effort is directed toward newer strategies targeted at the EGFR in CRC. A new generation of small-molecule TKIs is emerging in which multiple receptor pathways, including ErbB2 and vascular endothelial growth factor receptor, can be simultaneously targeted with EGFR. These agents are still in early-phase clinical trials, and specific data for patients with CRC are forthcoming.

Randomized phase II--study evaluating EGFR targeting therapy with cetuximab in combination with radiotherapy and chemotherapy for patients with locally advanced pancreatic cancer--PARC: study protocol [ISRCTN56652283]

BACKGROUND

Pancreatic cancer is the fourth commonest cause of death from cancer in men and women. Advantages in surgical techniques, radiation therapy techniques, chemotherapeutic regimes, and different combined-modality approaches have yielded only a modest impact on the prognosis of patients with pancreatic cancer. Thus there is clearly a need for additional strategies. One approach involves using the identification of a number of molecular targets that may be responsible for the resistance of cancer cells to radiation or to other cytotoxic agents. As such, these molecular determinants may serve as targets for augmentation of the radiotherapy or chemotherapy response. Of these, the epidermal growth factor receptor (EGFR) has been a molecular target of considerable interest and investigation, and there has been a tremendous surge of interest in pursuing targeted therapy of cancers via inhibition of the EGFR.

METHODS/DESIGN

The PARC study is designed as an open, controlled, prospective, randomized phase II trial. Patients in study arm A will be treated with chemoradiation using intensity modulated radiation therapy (IMRT) combined with gemcitabine and simultaneous cetuximab infusions. After chemoradiation the patients receive gemcitabine infusions weekly over 4 weeks. Patients in study arm B will be treated with chemoradiation using intensity modulated radiation therapy (IMRT) combined with gemcitabine and simultaneous cetuximab infusions. After chemoradiation the patients receive gemcitabine weekly over 4 weeks and cetuximab infusions over 12 weeks. A total of 66 patients with locally advanced adenocarcinoma of the pancreas will be enrolled. An interim analysis for patient safety reasons will be done one year after start of recruitment. Evaluation of the primary endpoint will be performed two years after the last patient's enrollment.

DISCUSSION

The primary objective of this study is to evaluate the feasibility and the toxicity profile of trimodal therapy in pancreatic adenocarcinoma with chemoradiation therapy with gemcitabine and intensity modulated radiation therapy (IMRT) and EGFR-targeted therapy using cetuximab and to compare between two different methods of cetuximab treatment schedules (concomitant versus concomitant and sequential cetuximab treatment). Secondary objectives are to determine the role and the mechanism of cetuximab in patient's chemoradiation regimen, the response rate, the potential of this combined modality treatment to concert locally advanced lesions to potentially resectable lesions, the time to progression interval and the quality of life.

Monoclonal antibodies and fusion proteins in medicine

Humanized antibodies and decoy receptors have been introduced in clinical practice to treat malignancies and systemic autoimmune disease because they ablate specific cells or disrupt pathogenic processes at distinct points. Reported clinical responses offer hope to treatment-resistant patients, particularly those with lymphomas and rheumatic diseases. Side effects from the use of biologic agents include lymphokine release syndrome, reactivation of tuberculosis, and immunosuppression. Further insights are needed regarding limitation of adverse effects, correct use in conjunction with existing drugs, and treatment of patients in whom resistance develops.

Induction of apoptosis in tumor-associated endothelial cells and therapy of orthotopic human pancreatic carcinoma in nude mice

Although gemcitabine has been accepted as the first-line chemotherapeutic reagent for advanced pancreatic cancer, improvement of response rate and survival is not sufficient and patients often develop resistance. We hypothesized that the inhibition of phosphorylation of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) on tumor cells and tumor-associated endothelial cells, combined with gemcitabine, would overcome the resistance to gemcitabine in orthotopic pancreatic tumor animal model. L3.6pl, human pancreatic cancer cells growing in the pancreas, and tumor-associated endothelial cells in microorgan environment highly expressed phosphorylated EGFR, VEGFR, and Akt, which regulates antiapoptotic mechanism. Oral administration of AEE788 (dual tyrosine kinase inhibitor against EGFR and VEGFR) inhibited the phosphorylation of EGFR, VEGFR, and Akt on tumor-associated endothelial cells as well as tumor cells. Although intraperitoneal (i.p.) injection of gemcitabine showed limited inhibitory effect on tumor growth, combination with AEE788 and gemcitabine produced nearly 95% inhibition of tumor growth in parallel with a high level of apoptosis on tumor cells and tumor-associated endothelial cells, and decreased microvascular density and proliferation rate. Collectively, these data indicate that dual inhibition of phosphorylation of EGFR and VEGFR, in combination with gemcitabine, produces apoptosis of tumor-associated endothelial cells and significantly suppresses human pancreatic cancer in nude mice.

Monoclonal antibodies targeting epidermal growth factor receptor and vascular endothelial growth factor with a focus on head and neck tumors

PURPOSE OF REVIEW

To provide an overview of recent clinical trials with monoclonal antibodies targeting epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in head and neck cancer (HNC) and in other tumors. To discuss future therapeutic strategies.

RECENT FINDINGS

Cetuximab, a chimeric monoclonal antibody targeting EGFR, has induced improved locoregional control and survival in combination with radiotherapy in a phase III study in locally advanced inoperable HNC. The recent Bowel Oncology with Cetuximab Antibody (BOND) study has shown that the combination of irinotecan and cetuximab yields a better response rate and a longer time to progression with respect to cetuximab monotherapy in irinotecan-refractory metastatic colorectal cancer, pointing to both a cetuximab single-agent activity and a cetuximab potential for reversal of irinotecan resistance. Non-small cell lung cancer and pancreatic cancer represent further areas for cetuximab development. Bevacizumab is a humanized monoclonal antibody that targets VEGF. It is the first antiangiogenic drug to have induced a survival advantage in cancer therapy, within a randomized trial of irinotecan, 5-fluorouracil, leucovorin (IFL) combined with bevacizumab or placebo in metastatic colorectal cancer. The use of bevacizumab in HNC is supported by preclinical evidence of an angiogenic loop; a few clinical trials are exploring the feasibility and the therapeutic potential of a combination of bevacizumab and EGFR-targeted drugs.

SUMMARY

Monoclonal antibodies targeting EGFR and VEGF represent exciting therapeutic strategies that should be further evaluated both in combination with drugs acting on the same target at a different level and in combination with other antisignaling agents acting on different pathways.

Cyclophosphamide Inhibition of Anti-CD40 Monoclonal Antibody–Based Therapy of B Cell Lymphoma Is Dependent on CD11b+ Cells

Monoclonal antibody (mAb)-based immunotherapy is now established as an important option for treating some cancers. The antitumor effects may be further enhanced by combining mAb with conventional chemotherapy. Certain novel immunomodulatory mAbs such as anti-CD40 have shown significant activity in preclinical models. We therefore assessed the efficacy of combining anti-CD40 mAb, known to elicit CTL responses against murine lymphoma models with the commonly used cytotoxic drug, cyclophosphamide. Using the syngeneic tumor model, BCL1, we have shown that timing of cyclophosphamide relative to mAb is critical to therapeutic outcome. Pretreatment with cyclophosphamide 7 to 10 days prior to mAb results in markedly reduced survival levels, similar to that achieved with cyclophosphamide alone. Conversely, when anti-CD40 is given before cyclophosphamide, the level of tumor protection was moderately increased. In vivo tracking experiments reveal that pretreatment with cyclophosphamide leads to diminished CTL expansion, as well as an increased number of CD11b+ cells that display an activated phenotype. These latter cells are able to inhibit T-cell proliferation, at least in part via production of nitric oxide, but do not induce T-cell apoptosis. Furthermore, adoptive transfer of the induced CD11b+ cells is sufficient to inhibit anti-CD40 therapy in tumor-bearing recipients. We have shown that the timing of cyclophosphamide relative to mAb administration is critical to the therapeutic outcome, and although the combination can improve survival, cyclophosphamide given prior to immunotherapy may generate a population of myeloid cells that can interfere with CTL responses and compromise the therapeutic outcome.

Linked Foreign T-Cell Help Activates Self-Reactive CTL and Inhibits Tumor Growth

Transgenic mice expressing membrane-bound OVA under the rat insulin promoter, RIP-mOVA, has previously been suggested to display deletional tolerance toward the dominant CTL epitope, SIINFEKL, and provide an elegant model system to test the hypothesis that the lack of T cell help contributes to the tolerance. To understand how the CD8 tolerance is maintained in these mice, a set of neo-self-Ags, OVA, modified to contain a foreign Th peptide, were constructed and tested for their ability to induce CTL responses in RIP-mOVA mice. Immunization with these Th peptide-modified OVA molecules and not with the wild-type OVA induced self-reactive CTLs recognizing dominant CTL peptide, SIINFEKL. Importantly, immunization with the modified OVA constructs also prevented the growth of OVA-expressing tumors in transgenic mice. Since endogenous OVA Th peptides did not contribute toward breaking self CTL tolerance, these results also highlighted a very robust CD4 T cell tolerance toward OVA in RIP-mOVA mice that has not been previously described. These results therefore provide direct evidence that it is the tolerance in the CD4 Th cell compartment that helps maintain the CTL tolerance against self-Ag in these mice. Since the CTL tolerance can be broken or bypassed by foreign Th peptides inserted into a self Ag, potential of using this approach in generating effective therapeutic cancer vaccines is discussed.

Immunotherapy for pancreatic cancer - science driving clinical progress

The identification of key signalling pathways involved in immune-system regulation, along with the development of early pancreatic tumours in mouse models have provided new opportunities for pancreatic cancer treatment and prevention. Immunotherapy for pancreatic cancer is one approach that is at a crucial crossroads, as therapeutics that are designed to target pancreatic-cancer-associated antigens and regulatory signalling molecules are entering clinical trials.

Chemotherapy for advanced pancreatic cancer: Past, present, and future

Advanced pancreatic cancer is a devastating illness characterized by significant morbidity and a brief median survival. Although standard chemotherapy with gemcitabine achieves only modest improvements in survival and quality of life, classic cytotoxic agents, such as 5-fluorouracil, pemetrexed, irinotecan, exatecan, cisplatin, or oxaliplatin, given alone or in combination with gemcitabine, have not proved superior. Thus, more recent trials have focused on targeting the biologic characteristics of pancreatic cancer. Although phase III trials of farnesyl transferase and matrix metalloproteinase inhibitors have not improved survival, encouraging preliminary results have been observed in phase II studies of inhibitors of the vascular endothelial growth factor and the epidermal growth factor receptor.

The anti-tumor effect of Apo2L/TRAIL on patient pancreatic adenocarcinomas grown as xenografts in SCID mice

Background

Apo2L/TRAIL has considerable promise for cancer therapy based on the fact that this member of the tumor necrosis factor family induces apoptosis in the majority of malignant cells, while normal cells are more resistant. Furthermore, in many cells, when Apo2L/TRAIL is combined with chemotherapy, the effect is synergistic. The majority of this work has been carried out using cell lines. Therefore, investigation of how patient tumors respond to Apo2L/TRAIL can validate and/or complement information obtained from cell lines and prove valuable in the design of future clinical trials.

Methods

We have investigated the Apo2L/TRAIL sensitivity of patient derived pancreatic tumors using a patient tumor xenograft/ SCID mouse model. Mice bearing engrafted tumors were treated with Apo2L/TRAIL, gemcitabine or a combination of both therapies.

Results

Patient tumors grown as xenografts exhibited a spectrum of sensitivity to Apo2L/TRAIL. Both Apo2L/TRAIL sensitive and resistant pancreatic tumors were found, as well as tumors that showed heterogeneity of response. Changes in apoptotic signaling molecules in a sensitive tumor were analyzed by Western blot following Apo2L/TRAIL treatment; loss of procaspase 8, Bid and procaspase 3 was observed and correlated with inhibition of tumor growth. However, in a tumor that was highly resistant to killing by Apo2L/TRAIL, although there was a partial loss of procaspase 8 and Bid in response to Apo2L/TRAIL treatment, loss of procaspase 3 was negligible. This resistant tumor also expressed a high level of the anti-apoptotic molecule Bcl-X_L that, in comparison, was not detected in a sensitive tumor. Importantly, in the majority of these tumors, addition of gemcitabine to Apo2L/TRAIL resulted in a greater anti-tumor effect than either therapy used alone.

Conclusion

These data suggest that in a clinical setting we will see heterogeneity in the response of patients' tumors to Apo2L/TRAIL, including tumors that are highly sensitive as well as those that are resistant. While much more work is needed to understand the molecular basis for this heterogeneity, it is very encouraging, that Apo2L/TRAIL in combination with gemcitabine increased therapeutic efficacy in almost every case and therefore may be a highly effective strategy for controlling human pancreatic cancer validating and expanding upon what has been reported for cell lines.

Therapeutic synergy of oral taxane BMS-275183 and cetuximab versus human tumor xenografts

PURPOSE

Combination therapy consisting of an oral taxane, BMS-275183, and the anti-epidermal growth factor receptor monoclonal antibody, cetuximab, was assessed for enhanced therapeutic benefit in preclinical tumor models.

EXPERIMENTAL DESIGN

Mice bearing human tumor xenografts, either L2987 lung or GEO colon carcinoma, were administered the aforementioned treatments singly or in combination regimens. Delays in tumor growth and tumor-free status were evaluated and combination treatments were assessed relative to optimal solo treatments.

RESULTS

Combination therapies with the oral taxane plus cetuximab were tolerated and therapeutic synergistic outcomes obtained. The therapeutic enhancements were >1 log cell kill greater than the antitumor effect caused by either solo agent applied optimally. For example, at the maximum-tolerated dose of BMS-275183, 60 mg/kg/administration, given p.o. once every 3 days for a total of six administrations (q3dx6), 1.0 gross log cell kill was achieved in mice bearing well established (100 to 200 mg) s.c. implanted L2987 tumors. Cetuximab, at an optimal dose of 1 mg/mouse, given i.p. q3dx6, produced 1.3 log cell kill. When cetuximab, 1 mg/mouse, i.p., plus BMS-275183, 25 mg/kg/administration, p.o., were both given q3dx6, the result was 2.6 log cell kill with three of eight mice cured (P < 0.01). Similar efficacy benefits were obtained in the GEO tumor model.

CONCLUSIONS

The combination of oral taxane BMS-275183 plus cetuximab provided therapeutically synergistic antitumor activity in two different human tumor xenograft models. Clinical evaluation of this combination is recommended.

Treatment for pancreatic cancer: current therapy and continued progress

In the last decade, continued efforts in pancreas cancer research have led to the development of new, more effective therapies. Additionally, progress in understanding the molecular processes underlying the development and progression of this disease provides hope for the development of more effective treatment strategies. Recent clinical trials have provided reason for hope that novel chemotherapy combinations and molecularly targeted agents will lead to improved clinical outcomes for patients with this disease. This article will summarize the data that has led to the current standards of therapy for patients with resectable and advanced pancreatic cancer and review new treatment strategies for this disease.

Molecular Mechanisms of Resistance to Therapies Targeting the Epidermal Growth Factor Receptor

Targeted therapies that inhibit the activity of tyrosine kinase receptors such as the epidermal growth factor receptor (EGFR) have shown activity against solid malignancies when used as single agents or in combination with chemotherapy. Although anti-EGFR therapies are active in some patients, eventually disease in nearly all patients will become refractory to therapy. Therefore, a better understanding of the mechanisms of resistance to anti-EGFR therapies is critical to further improve the efficacy of this class of agents. Mechanisms that mediate resistance to anti-EGFR therapies include the presence of redundant tyrosine kinase receptors, increased angiogenesis, and the constitutive activation of downstream mediators. Two recent landmark publications have also shown that specific mutations in the kinase domain of EGFR in some lung carcinomas are associated with markedly improved response rates to an EGFR tyrosine kinase inhibitor. Mutations in the EGFR receptor seem to play a significant role in determining the sensitivity of tumor cells to EGFR inhibitor therapy by altering the conformation and activity of the receptor. As the field of molecular therapeutics continues to evolve, a comprehensive understanding of resistance mechanisms will ultimately lead to refinements in our regimens to provide better care for patients with cancer.

Predictors of Sensitivity and Resistance to Epidermal Growth Factor Receptor Inhibitors

Lung cancer is one of the leading types of cancer with an associated high mortality. Currently, treatment with conventional cytotoxic agents remains suboptimal. Inhibition of the epidermal growth factor receptor (EGFR) with monoclonal antibodies or small-molecule inhibitors of the tyrosine kinase (TK) domain of the receptor have demonstrated modest, albeit significant, antitumor activities in patients with non-small-cell lung cancer (NSCLC). The goal of any targeted therapy is to direct treatment to those patients who are more likely to derive benefit from such a treatment. Two interventions may improve the predicted sensitivity to these agents: (1) the use of a real predictor before treatment, represented by pharmacodiagnostic tests, and (2) studying the relationship between an early event after treatment and outcome, represented by pharmacodynamic tests. Pharmacodiagnostic factors that have been studied include the clinical features and histologic subtype of the tumor, the presence of somatic mutations in the TK domain of the EGFR, the expression of the receptor itself, and the activation of the receptor signaling pathway. Pharmacodynamic events associated with improved outcome include drug-induced rash and regulation of the receptor expression. Currently, the best established determinant of response to small-molecule inhibitors of the EGFR is the presence of activating mutations in the receptor TK domain. However, it is not known whether these functional mutations are involved in the response of NSCLC to monoclonal antibodies. Further investigation is needed to better predict patients who are more likely to benefit from these drugs.

Mechanisms of resistance to Erbitux (anti-epidermal growth factor receptor) combination therapy in pancreatic adenocarcinoma cells

We previously demonstrated that pancreatic adenocarcinoma BxPC-3 xenografts display resistance to treatment with Erbitux, gemcitabine, and radiation, whereas MIA PaCa-2 xenografts are highly sensitive to the same therapy. Here, we elucidate in vitro mechanisms that may explain the observed differential response of epidermal growth factor receptor (EGFR) expressing pancreatic adenocarcinoma xenografts to Erbitux-based combination therapy in vivo. MIA PaCa-2 and BxPC-3 protein lysates were probed with antibodies to EGFR, ErbB2, ErbB3, and ErbB4. Constitutive ErbB3 activity was visualized by immunoblot analysis using anti-phosphotyrosine antibodies and receptor-specific immunoprecipitates. erbB2 and erbB3 gene expression in both cell lines was quantified with real-time polymerase chain reaction. Erbitux-induced internalization of EGFR was determined by flow cytometry following Erbitux treatment for different incubation times at 0 degrees C and 37 degrees C. MIA PaCa-2 and BxPC-3 protein extracts were also probed with anti-phospho-mitogen-activated protein kinase antibody after stimulation with EGF and in the presence of Erbitux. Although both cell lines expressed EGFR and ErbB2 protein, ErbB3 protein was selectively expressed by BxPC-3 cells, where it also showed evidence of constitutive phosphorylation. There was a 10-fold increase of erbB3 transcript levels in BxPC-3 cells compared with MIA PaCa-2. ErbB4 protein was not detectable in either cell line. Erbitux mediated EGFR internalization in MIA PaCa-2 cells after 2 hours of incubation, whereas it did not promote EGFR internalization in BxPC-3 cells. Likewise, EGF-dependent phosphorylation of MAPK p44/42 was blocked by Erbitux treatment in MIA PaCa-2 but not BxPC-3 cells. Erbitux selectively interfered with EGF-induced MAPK activation in MIA PaCa-2 but not BxPC-3 cells. Persistent MAPK activation and impaired in vitro internalization of EGFR by BxPC-3 pancreatic cancer cells may be due to constitutive ErbB3 signaling, facilitated by heterodimerization with EGFR, which may explain resistance to Erbitux-based combination therapy in vivo.