Novel thiosemicarbazone iron chelators induce up-regulation and phosphorylation of the metastasis suppressor N-myc down-stream regulated gene 1: a new strategy for the treatment of pancreatic cancer

Pancreatic cancer is an aggressive neoplasm, with a mortality rate close to 100%. The most successful agent for pancreatic cancer treatment is gemcitabine, although the overall effect in terms of patient survival remains very poor. This study was initiated to evaluate a novel class of anticancer agents against pancreatic cancer. This group of compounds belongs to the dipyridyl thiosemicarbazone class that have been shown to have potent and selective activity against a range of different neoplasms in vitro and in vivo. We demonstrate for the first time in pancreatic cancer that these agents increase the expression of the growth and metastasis suppressor N-myc downstream-regulated gene 1 and its phosphorylation at Ser330 and Thr346 that is important for its activity against this tumor. In addition, these agents increased expression of the cyclin-dependent kinase inhibitor p21(CIP1/WAF1), whereas decreasing cyclin D1 in pancreatic cancer cells. Together, these molecular alterations account, in part, for the pronounced antitumor activity observed. Indeed, these agents had significantly higher antiproliferative activity in vitro than the established treatments for pancreatic cancer, namely gemcitabine and 5-fluorouracil. Studies in vivo demonstrated that a novel thiosemicarbazone, namely di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone hydrochloride, completely inhibited the growth of pancreatic cancer xenografts with no evidence of marked alterations in normal tissue histology. Together, our studies have identified molecular effectors of a novel and potent antitumor agent that could be useful for pancreatic cancer treatment.     

Role of platinum agents in the management of advanced pancreatic cancer

Pancreatic cancer, one of the most common gastrointestinal tumors, has a 5-year survival rate of < 5%. Since 1997, when gemcitabine showed superior clinical benefit to single-agent 5-fluorouracil, it has remained the only standard chemotherapy approved by the US FDA for the treatment of advanced pancreatic cancer. Numerous new agents, both cytotoxic and targeted, have been tested against and in combination with this standard. Many combination therapy regimens showed encouraging results in Phase II settings, which led to > 12 randomized Phase III trials in the last decade. Some trials showed improved response rates or progression-free survival, but there was no clear improvement in survival. Among these combinations, the combination of gemcitabine plus platinum agents showed improved progression-free survival or time-to-tumor progression, but failed to demonstrate a survival advantage over gemcitabine. This combination has regained attention after a recent pooled analysis and a meta-analysis suggested a survival benefit of gemcitabine-platinum doublets when compared with single agent gemcitabine. There are preclinical data showing synergism between gemcitabine and platinum agents. Hence, this review covers the role of platinum doublets in the treatment of metastatic pancreatic cancer.     

Role of platinum agents in the management of advanced pancreatic cancer

Pancreatic cancer, one of the most common gastrointestinal tumors, has a 5-year survival rate of < 5%. Since 1997, when gemcitabine showed superior clinical benefit to single-agent 5-fluorouracil, it has remained the only standard chemotherapy approved by the US FDA for the treatment of advanced pancreatic cancer. Numerous new agents, both cytotoxic and targeted, have been tested against and in combination with this standard. Many combination therapy regimens showed encouraging results in Phase II settings, which led to > 12 randomized Phase III trials in the last decade. Some trials showed improved response rates or progression-free survival, but there was no clear improvement in survival. Among these combinations, the combination of gemcitabine plus platinum agents showed improved progression-free survival or time-to-tumor progression, but failed to demonstrate a survival advantage over gemcitabine. This combination has regained attention after a recent pooled analysis and a meta-analysis suggested a survival benefit of gemcitabine-platinum doublets when compared with single agent gemcitabine. There are preclinical data showing synergism between gemcitabine and platinum agents. Hence, this review covers the role of platinum doublets in the treatment of metastatic pancreatic cancer.     

Novel treatments and therapies in development for pancreatic cancer

Until recently, 5-fluorouracil was the most widely used treatment for non-resectable pancreatic cancer. This treatment, however, only resulted in a median survival time of approximately 4 months. In the last few years, gemcitabine has rapidly become the new treatment benchmark, due more to its superior clinical benefit rather than to it conferring an increased median survival (approximately 5-6 months). Thus, the outlook for patients with pancreatic cancer is still relatively bleak. A number of new treatment options are presently being investigated. Some of these are combination therapies involving gemcitabine and other chemotherapeutic agents or radiation. Other novel treatment strategies are also already being evaluated in clinical studies. Some of the more promising treatments in development are discussed and evaluated in this article.     

Novel treatments and therapies in development for pancreatic cancer

Until recently, 5-fluorouracil was the most widely used treatment for non-resectable pancreatic cancer. This treatment, however, only resulted in a median survival time of ~ 4 months. In the last few years, gemcitabine has rapidly become the new treatment benchmark, due more to its superior clinical benefit rather than to it conferring an increased median survival (～ 5 – 6 months). Thus, the outlook for patients with pancreatic cancer is still relatively bleak. A number of new treatment options are presently being investigated. Some of these are combination therapies involving gemcitabine and other chemotherapeutic agents or radiation. Other novel treatment strategies are also already being evaluated in clinical studies. Some of the more promising treatments in development are discussed and evaluated in this article.     

Novel non-operative treatment and treatment strategies in pancreatic cancer

Patients with advanced pancreatic cancer have traditionally been treated with palliative care only. The last decade has seen significant improvements in the surgical treatment of this disease but until the late 1990s there was no effective non-surgical treatment for these tumours. The introduction of gemcitabine has given clinicians treating patients with pancreatic cancer a new option. The published randomised data of gemcitabine in patients with pancreatic cancer has shown both a small survival advantage and significant improvements in quality of life indicators in these patients. These data have stimulated a resurgence of interest in pancreatic tumours and several studies have been or are currently investigating novel treatments or treatment strategies. The explosion in the molecular knowledge of cancer has led to the development of several ‘molecular designer drugs’ that have been tested in pancreatic cancer. The furthest advanced of these is a matrix metalloproteinase (MMP) inhibitor called marimastat. The first randomised data using this new class of agents is increasing and suggests that marimastat may have a role in the future treatment of patients with pancreatic cancer. Other agents such as gastrimmune, are about to enter Phase III studies and several other molecular treatment strategies are progressing from the in vitro stage towards the clinical arena. Each of these treatments and treatment regimens are discussed along with their current progress.     

Novel non-operative treatment and treatment strategies in pancreatic cancer

Patients with advanced pancreatic cancer have traditionally been treated with palliative care only. The last decade has seen significant improvements in the surgical treatment of this disease but until the late 1990s there was no effective non-surgical treatment for these tumours. The introduction of gemcitabine has given clinicians treating patients with pancreatic cancer a new option. The published randomised data of gemcitabine in patients with pancreatic cancer has shown both a small survival advantage and significant improvements in quality of life indicators in these patients. These data have stimulated a resurgence of interest in pancreatic tumours and several studies have been or are currently investigating novel treatments or treatment strategies. The explosion in the molecular knowledge of cancer has led to the development of several 'molecular designer drugs' that have been tested in pancreatic cancer. The furthest advanced of these is a matrix metalloproteinase (MMP) inhibitor called marimastat. The first randomised data using this new class of agents is increasing and suggests that marimastat may have a role in the future treatment of patients with pancreatic cancer. Other agents such as gastrimmune, are about to enter Phase III studies and several other molecular treatment strategies are progressing from the in vitro stage towards the clinical arena. Each of these treatments and treatment regimens are discussed along with their current progress.     

Management of advanced pancreatic cancer

Each year, approximately 37,000 new patients are diagnosed with pancreatic cancer (PC) in the USA. The incidence has been increasing since the 1930s. Prognosis of PC is extremely poor. In the USA, approximately 34,000 patients die from PC each year, making it the fourth leading cause of cancer-related death in the USA. The 5-year overall survival rate for advanced pancreatic cancer is less than 5%. Poor prognosis has been attributed to the inability to diagnose, while the tumor is resectable and its propensity toward early vascular dissemination and spread to regional lymph nodes. One of the greatest challenges in the treatment of pancreatic cancer remains its inherent lack of beneficial response to cytotoxic chemotherapy. For inoperable PC, gemcitabine is the only cytotoxic agent approved by the US FDA since 1997. Several trials have evaluated whether there is any benefit for gemcitabine-based combinations, including molecular targeted agents, over gemcitabine alone. Although several of these have shown a higher response rate favoring the combined regimens, a clear benefit in overall survival has yet to be shown. Despite the benefit of gemcitabine, most patients with advanced disease still do poorly, with a median time-to-tumor progression between 2 and 3 months and median overall survival of 4–6 months. The authors review slow progress and the recent developments with newer chemotherapeutic and molecular-targeted agents in the management of pancreatic cancer.     

Management of advanced pancreatic cancer

Each year, approximately 37,000 new patients are diagnosed with pancreatic cancer (PC) in the USA. The incidence has been increasing since the 1930s. Prognosis of PC is extremely poor. In the USA, approximately 34,000 patients die from PC each year, making it the fourth leading cause of cancer-related death in the USA. The 5-year overall survival rate for advanced pancreatic cancer is less than 5%. Poor prognosis has been attributed to the inability to diagnose, while the tumor is resectable and its propensity toward early vascular dissemination and spread to regional lymph nodes. One of the greatest challenges in the treatment of pancreatic cancer remains its inherent lack of beneficial response to cytotoxic chemotherapy. For inoperable PC, gemcitabine is the only cytotoxic agent approved by the US FDA since 1997. Several trials have evaluated whether there is any benefit for gemcitabine-based combinations, including molecular targeted agents, over gemcitabine alone. Although several of these have shown a higher response rate favoring the combined regimens, a clear benefit in overall survival has yet to be shown. Despite the benefit of gemcitabine, most patients with advanced disease still do poorly, with a median time-to-tumor progression between 2 and 3 months and median overall survival of 4-6 months. The authors review slow progress and the recent developments with newer chemotherapeutic and molecular-targeted agents in the management of pancreatic cancer.     

Gemcitabine in the treatment of bladder cancer

New agents are available for the treatment of metastatic transitional cell carcinoma of the bladder. In the US, the combination of methotrexate, vinblastine, doxorubicin and cisplatin (M-VAC) remains the standard chemotherapy regimen for advanced bladder cancer. Gemcitabine (2′,2′-difluorodeoxycytidine [dFdC]) is a relatively new agent with a favourable toxicity profile that has demonstrated activity against a number of solid tumours in both preclinical and clinical studies. Single-agent gemcitabine has shown activity in bladder cancer in both pretreated and chemotherapy-naïve patients. The combination of gemcitabine plus cisplatin is a regimen with significant activity and moderate toxicity in bladder cancer patients. A randomised trial of gemcitabine plus cisplatin versus M-VAC has completed accrual but has not yet been reported. New combination studies of gemcitabine with other chemotherapy agents, including the taxanes, are ongoing.     

Gemcitabine in the treatment of bladder cancer

New agents are available for the treatment of metastatic transitional cell carcinoma of the bladder. In the US, the combination of methotrexate, vinblastine, doxorubicin and cisplatin (M-VAC) remains the standard chemotherapy regimen for advanced bladder cancer. Gemcitabine (2',2'-difluorodeoxycytidine [dFdC]) is a relatively new agent with a favourable toxicity profile that has demonstrated activity against a number of solid tumours in both preclinical and clinical studies. Single-agent gemcitabine has shown activity in bladder cancer in both pretreated and chemotherapy-na?ve patients. The combination of gemcitabine plus cisplatin is a regimen with significant activity and moderate toxicity in bladder cancer patients. A randomised trial of gemcitabine plus cisplatin versus M-VAC has completed accrual but has not yet been reported. New combination studies of gemcitabine with other chemotherapy agents, including the taxanes, are ongoing.     

Emerging drugs in pancreatic cancer

Improving survival in patients with pancreatic cancer remains a formidable challenge. For the few patients with localised stages of the disease, intra-operative radiotherapy, adjuvant chemoradiotherapy and neo-adjuvant therapies remain non-validated and the survival benefit conferred by 5-fluorouracil-folinic acid adjuvant chemotherapy over radical surgery alone is still a matter of debate. Gemcitabine has recently emerged as the standard single agent in advanced stages of the disease and pharmacokinetic refinements such as the use of a fixed-dose infusion rate may further improve still rather modest result figures. At present, most efforts deal with the development of more effective doublet or triplet therapies, combining gemcitabine with either conventional cytotoxic drugs--the most promising being oxaliplatin--or more innovative, targeted therapeutic agents. Among these agents, matrix metalloprotease inhibitors and farnesyltransferase inhibitors have already undergone Phase III trials, alone or in combination with gemcitabine, with rather disappointing results. However, preclinical and Phase I and II studies of cyclooxygenase-2 or lipoxygenase inhibitors, various immunotherapeutic approaches and several tyrosine kinase inhibitors or monoclonal antibodies against growth factors or their receptors are encouraging and may provide some hope for patients with pancreatic cancer.     

Phase II study with 5-fluorouracil and ginkgo biloba extract (GBE 761 ONC) in patients with pancreatic cancer

The aim of the study was to evaluate the efficacy and tolerability of as well as the quality of life under treatment with 5-fluorouracil (CAS 51-21-8, 5-FU) combined with parenteral GBE 761 ONC (i.e. the ginkgo biloba special extract EGb 761) in patients with pancreatic cancer. Forty-eight patients with locally or metastatic advanced pancreatic cancer were treated within a phase II study. The treatment was repeated every three weeks until progression. Response to therapy was evaluated after 2 and 4 treatment courses. Thirty-two patients were evaluable for response. Progressive disease was observed in 22 (68.8%) patients, no change in 7 (21.9%) patients and partial response in 3 (9.4%) patients (overall response = 9.4%). GBE 761 ONC was well tolerated. Adverse events which occurred during the study consisted mainly of myelosuppression and gastrointestinal symptoms and were judged as 5-FU-related or consisted of liver toxicity, respectively, and were judged as tumour-related. These results suggest a good benefit-risk ratio of the combination of 5-FU and GBE 761 ONC in the treatment of pancreatic cancer. In comparison with the results of studies with either 5-FU or gemcitabine as single agents the combination of 5-FU/GBE 761 ONC shows comparable response rates. The toxicity of the 5-FU/GBE 761 ONC combination was low. This combination therapy therefore warrants further clinical investigation, such as a controlled clinical trial against 5-FU or gemcitabine monotherapy.     

Gemcitabine-related radiation recall in a patient with pancreatic cancer

Radiation recall refers to inflammatory reactions triggered by chemotherapeutic agents and develops cutaneously in the previously irradiated areas. Such agents include anthracyclines, taxanes and capecitabine. Radiation recall related to gemcitabine has been reported in lung and breast cancer. Similar phenomenon associated with gemcitabine, the only FDA-approved drug for pancreatic cancer, is rarely reported. We report a patient with inoperable pancreatic cancer who developed gastrointestinal bleeding secondary to radiation-recall related to gemcitabine and review literature. A 57-year-old white male with unresectable pancreatic cancer received capecitabine in combination with radiation therapy followed by capecitabine alone given over approximately a 3-month time period. Computed tomography re-evaluation demonstrated a new liver lesion. The patient was then treated with gemcitabine and irinotecan. On day 15 of cycle 1, he reported progressive worsening of weakness and fatigue, and melena. Physical examination revealed hypotension (84/47 mmHg) and heme-positive stool on rectal examination. He denied aspirin or non-steroidal anti-inflammatory drug use. Chemotherapy was held. Hematocrit was 20% (previously 33%). He was transfused with 3 units of packed red blood cells. An esophago-gastro-duodenal examination was performed which showed antritis and duodenitis consistent with radiation therapy. A single site of oozing was injected with epinephrine. The diffuse gastritis was aggressively treated with proton pump inhibitors. The patient's hematocrit eventually stabilized and was 30% at discharge. Gemcitabine was not resumed. Radiation recall from gemcitabine is rare, but can potentially arise in any site that has been previously irradiated. Gemcitabine should be added to the list of drugs known to cause radiation recall. Treating physicians must be aware of this potential toxicity from gemcitabine either given concomitantly or followed by radiation. We suggest discontinuing gemcitabine if radiation recall is observed. Further studies are warranted into the pathogenesis of this unique phenomenon.     

Advanced stage pancreatic cancer: novel therapeutic options

Despite advances in our understanding of the molecular and genetic basis of pancreatic cancer, it continues to be a therapeutic challenge. Gemcitabine approved by FDA in 1997, offers modest improvement of tumor-related symptoms and marginal advantage of survival. Many chemotherapeutic agents have been compared against or combined with gemcitabine in randomized Phase III trials and no drug was shown to be superior to single-agent gemcitabine except FOLFIRINOX and nab-paclitaxel plus gemcitabine. On the other hand, efforts to integrate targeted agents such as BAY 12-9566, SCH 66336, bevacizumab, cetuximab, axitinib and sorafenib have been quite dismal despite extensive pre-clinical and clinical research over the last decade in the field of novel agents. To date, erlotinib remains the only biological agent that has demonstrated a small, but significant, added benefit to single agent gemcitabine. However, numerous new agents, including monoclonal antibodies and tyrosine kinase inhibitors, are currently being tested in an attempt to achieve better response, while maintaining a safe toxicity profile. In this article, the author discusses the management of advanced pancreatic and the current role of novel agents in this setting.     

Recent developments in the pharmacological treatment of advanced pancreatic cancer

Metastatic pancreatic cancer is one of the leading causes of cancer-related death in North America and Europe. The high mortality rate associated with pancreatic cancer is related to the fact that the vast majority of patients develop incurable, metastatic disease. Such patients have, in the past, had few treatment options. In recent years, however, the systemic administration of gemcitabine has been accepted as a standard first-line treatment for patients with advanced pancreatic cancer. While treatment with gemcitabine has been shown to result in both clinical benefit and in prolongation of survival, objective tumour responses following therapy with gemcitabine are relatively uncommon and median survival times remain short. Current efforts have, therefore, focused on evaluating chemotherapy regimens in which gemcitabine is combined with a second cytotoxic agent. Several such combinations appear to be associated with higher objective response rates than single-agent gemcitabine and have been well-tolerated in early clinical trials. Ongoing, prospectively randomised clinical trials will help better define the efficacy of these new combinations and will determine if they result in a significant benefit when compared to gemcitabine monotherapy. A number of novel chemotherapeutic and biological agents also appear promising and are likely to play a future role in the treatment of patients with advanced pancreatic cancer.     

Recent developments in the pharmacological treatment of advanced pancreatic cancer

Metastatic pancreatic cancer is one of the leading causes of cancer-related death in North America and Europe. The high mortality rate associated with pancreatic cancer is related to the fact that the vast majority of patients develop incurable, metastatic disease. Such patients have, in the past, had few treatment options. In recent years, however, the systemic administration of gemcitabine has been accepted as a standard first-line treatment for patients with advanced pancreatic cancer. While treatment with gemcitabine has been shown to result in both clinical benefit and in prolongation of survival, objective tumour responses following therapy with gemcitabine are relatively uncommon and median survival times remain short. Current efforts have, therefore, focused on evaluating chemotherapy regimens in which gemcitabine is combined with a second cytotoxic agent. Several such combinations appear to be associated with higher objective response rates than single-agent gemcitabine and have been well-tolerated in early clinical trials. Ongoing, prospectively randomised clinical trials will help better define the efficacy of these new combinations and will determine if they result in a significant benefit when compared to gemcitabine monotherapy. A number of novel chemotherapeutic and biological agents also appear promising and are likely to play a future role in the treatment of patients with advanced pancreatic cancer.     

Pancreatic cancer: a review of recent advances

Pancreatic cancer is one of the most common causes of cancer-related death. Despite the advances of the molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. Overall, the 5-year survival rate is < 5% and only approximately 20% of the 10% of patients with resectable disease survive 5 years. Recently, the European Study Group for Pancreatic Cancer 1 trial demonstrated substantially increased survival from adjuvant chemotherapy with 5-fluorouracil-folinic acid and preliminary data showed prolonged disease-free survival from adjuvant gemcitabine. Current palliative therapeutic approaches mostly focused on evaluating chemotherapy regimens in which gemcitabine is combined with a second cytotoxic agent. Recently, large randomised trials of combinations of gemcitabine with either capecitabine or with erlotinib demonstrated prolonged survival and 1-year survival rates of approximately 25%. The advance of molecular biology has led to the elucidation of molecular events that are important for pancreatic carcinogenesis and has provided a foundation for the development of novel chemotherapeutic and biological agents that appear to be promising and are likely to play a future role in the treatment of patients with advanced pancreatic cancer.     

Cytotoxic chemotherapy for pancreatic cancer: Advances to date and future directions

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.     

Conventional chemotherapy of advanced pancreatic cancer

The vast majority of patients with pancreatic cancer present with locally advanced unresectable or metastatic disease, and in this setting only a palliative treatment can be offered. Single-agent gemcitabine has been considered the standard chemotherapy for patients with advanced pancreatic cancer since the results of a pivotal phase III trial showing superior clinical benefit compared to bolus 5-fluorouracil were published in 1997. In recent years, many randomized trials have attempted to improve results obtained with gemcitabine exploring a different schedule (fixed dose rate) of its administration, or testing the addition of one or more drugs to gemcitabine. Unfortunately, none of these trials produced a statistically significant and clinically relevant improvement in overall survival compared to the standard. A randomized phase III trial has recently shown a survival advantage using a combination of more drugs (FOLFIRINOX: irinotecan, oxaliplatin, folinic acid and 5-fluorouracil) compared to single-agent gemcitabine, suggesting that regimens without gemcitabine can be successfully used in patients with advanced pancreatic cancer. FOLFIRINOX was associated with worse toxicity than gemcitabine, and the available data suggest that this regimen may be considered for patients with metastatic pancreatic cancer who are fit enough to withstand potential side effects. The best option for these patients remains the enrolment in prospective clinical trials. Improvements in the treatment of the advanced disease will possibly derive from new combinations or from new drugs, but certainly from a better knowledge of the multiple molecular pathways implicated in pancreatic carcinogenesis and in invasion and metastasis.