Weekly paclitaxel, gemcitabine, and external irradiation followed by randomized farnesyl transferase inhibitor R115777 for locally advanced pancreatic cancer

Preoperative chemotherapy, radiotherapy and surgical decision-making in patients with borderline resectable and locally advanced pancreatic cancer

Surgical resection combined with systemic chemotherapy is the cornerstone of treatment for patients with localized pancreatic cancer. Upfront surgery is considered suboptimal in cases with extensive vascular involvement, which can be classified as either borderline resectable pancreatic cancer or locally advanced pancreatic cancer. In these patients, FOLFIRINOX or gemcitabine plus nab-paclitaxel chemotherapy is currently used as preoperative chemotherapy and is eventually combined with radiotherapy. Thus, more patients might reach 5-year overall survival. Patient selection for chemotherapy, radiotherapy and subsequent surgery is based on anatomical, biological and conditional parameters. Current guidelines and clinical practices vary considerably regarding preoperative chemotherapy and radiotherapy, response evaluation, and indications for surgery. In this Review, we provide an overview of the clinical evidence regarding disease staging, preoperative therapy, response evaluation and surgery in patients with borderline resectable pancreatic cancer or locally advanced pancreatic cancer. In addition, a clinical work-up is proposed based on the available evidence and guidelines. We identify knowledge gaps and outline a proposed research agenda.

Targeting KRAS for the potential treatment of pancreatic ductal adenocarcinoma: Recent advancements provide hope (Review)

Kirsten rat sarcoma viral oncogene homolog (KRAS) is one of the most frequently mutated oncogenes in solid tumors. More than 90% of pancreatic ductal adenocarcinoma (PDAC) are driven by mutations in the KRAS gene, suggesting the importance of targeting this oncogene in PDAC. Initial efforts to target KRAS have been unsuccessful due to its small size, high affinity for guanosine triphosphate/guanosine diphosphate, and lack of distinct drug‑binding pockets. Therefore, much of the focus has been directed at inhibiting the activation of major signaling pathways downstream of KRAS, most notably the PI3K/AKT and RAF/MAPK pathways, using tyrosine kinase inhibitors and monoclonal antibodies. While preclinical studies showed promising results, clinical data using the inhibitors alone and in combination with other standard therapies have shown limited practicality, largely due to the lack of efficacy and dose‑limiting toxicities. Recent therapeutic approaches for KRAS‑driven tumors focus on mutation‑specific drugs such as selective KRASG12C inhibitors and son of sevenless 1 pan‑KRAS inhibitors. While KRASG12C inhibitors showed great promise against patients with non‑small cell lung cancer (NSCLC) harboring KRASG12C mutations, they were not efficacious in PDAC largely because the major KRAS mutant isoforms in PDAC are G12D, G12V, and G12R. As a result, KRASG12D and pan‑KRAS inhibitors are currently under investigation as potential therapeutic options for PDAC. The present review summarized the importance of KRAS oncogenic signaling, challenges in its targeting, and preclinical and clinical targeted agents including recent direct KRAS inhibitors for blocking KRAS signaling in PDAC.

Therapeutic resistance in pancreatic ductal adenocarcinoma: Current challenges and future opportunities

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States. Although chemotherapeutic regimens such as gemcitabine+ nab-paclitaxel and FOLFIRINOX (FOLinic acid, 5-Fluroruracil, IRINotecan, and Oxaliplatin) significantly improve patient survival, the prevalence of therapy resistance remains a major roadblock in the success of these agents. This review discusses the molecular mechanisms that play a crucial role in PDAC therapy resistance and how a better understanding of these mechanisms has shaped clinical trials for pancreatic cancer chemotherapy. Specifically, we have discussed the metabolic alterations and DNA repair mechanisms observed in PDAC and current approaches in targeting these mechanisms. Our discussion also includes the lessons learned following the failure of immunotherapy in PDAC and current approaches underway to improve tumor's immunological response.

Modulated Electro-Hyperthermia Resolves Radioresistance of Panc1 Pancreas Adenocarcinoma and Promotes DNA Damage and Apoptosis In Vitro

The poor outcome of pancreas ductal adenocarcinomas (PDAC) is frequently linked to therapy resistance. Modulated electro-hyperthermia (mEHT) generated by 13.56 MHz capacitive radiofrequency can induce direct tumor damage and promote chemo- and radiotherapy. Here, we tested the effect of mEHT either alone or in combination with radiotherapy using an in vivo model of Panc1, a KRAS and TP53 mutant, radioresistant PDAC cell line. A single mEHT shot of 60 min induced ~50% loss of viable cells and morphological signs of apoptosis including chromatin condensation, nuclear shrinkage and apoptotic bodies. Most mEHT treatment related effects exceeded those of radiotherapy, and these were further amplified after combining the two modalities. Treatment related apoptosis was confirmed by a significantly elevated number of annexin V single-positive and cleaved/activated caspase-3 positive tumor cells, as well as sub-G1-phase tumor cell fractions. mEHT and mEHT+radioterapy caused the moderate accumulation of γH2AX positive nuclear foci, indicating DNA double-strand breaks and upregulation of the cyclin dependent kinase inhibitor p21^waf1 besides the downregulation of Akt signaling. A clonogenic assay revealed that both mono- and combined treatments affected the tumor progenitor/stem cell populations too. In conclusion, mEHT treatment can contribute to tumor growth inhibition and apoptosis induction and resolve radioresistance of Panc1 PDAC cells.

Biological determinants of radioresistance and their remediation in pancreatic cancer

Despite recent advances in radiotherapy, a majority of patients diagnosed with pancreatic cancer (PC) do not achieve objective responses due to the existence of intrinsic and acquired radioresistance. Identification of molecular mechanisms that compromise the efficacy of radiation therapy and targeting these pathways is paramount for improving radiation response in PC patients. In this review, we have summarized molecular mechanisms associated with the radio-resistant phenotype of PC. Briefly, we discuss the reversible and irreversible biological consequences of radiotherapy, such as DNA damage and DNA repair, mechanisms of cancer cell survival and radiation-induced apoptosis following radiotherapy. We further describe various small molecule inhibitors and molecular targeting agents currently being tested in preclinical and clinical studies as potential radiosensitizers for PC. Notably, we draw attention towards the confounding effects of cancer stem cells, immune system, and the tumor microenvironment in the context of PC radioresistance and radiosensitization. Finally, we discuss the need for examining selective radioprotectors in light of the emerging evidence on radiation toxicity to non-target tissue associated with PC radiotherapy.

Systematic review on the treatment of isolated local recurrence of pancreatic cancer after surgery; re-resection, chemoradiotherapy and SBRT

BACKGROUND

The majority of patients who have undergone a pancreatic resection for pancreatic cancer develop disease recurrence within two years. In around 30% of these patients, isolated local recurrence (ILR) is found. The aim of this study was to systematically review treatment options for this subgroup of patients.

METHODS

A systematic search was performed in PubMed, Embase and the Cochrane Library. Studies reporting on the treatment of ILR after initial curative-intent resection of primary pancreatic cancer were included. Primary endpoints were morbidity, mortality and survival after ILR treatment.

RESULTS

After screening 1152 studies, 18 studies reporting on 313 patients undergoing treatment for ILR were included. Treatment options for ILR included surgical re-resection (8 studies, 100 patients), chemoradiotherapy (7 studies, 153 patients) and stereotactic body radiation therapy (SBRT) (4 studies, 60 patients). Morbidity and mortality were reported for re-resection (29% and 1%, respectively), chemoradiotherapy (54% and 0%) and SBRT (3% and 1%). Most patients had a prolonged disease-free interval before recurrence. Median survival after treatment of ILR of up to 32, 19 and 16 months was reported for re-resection, chemoradiotherapy and SBRT, respectively.

CONCLUSION

In selected patients, treatment of ILR following pancreatic resection for pancreatic cancer seems safe, feasible and associated with relatively good survival.

Liposome Delivery Systems for Inhalation: A Critical Review Highlighting Formulation Issues and Anticancer Applications

This is a critical review on research conducted in the field of pulmonary delivery of liposomes. Issues relating to the mechanism of nebulisation and liposome composition were appraised and correlated with literature reports of liposome formulations used in clinical trials to understand the role of liposome size and composition on therapeutic outcome. A major highlight was liposome inhalation for the treatment of lung cancers. Many in vivo studies that explored the potential of liposomes as anticancer carrier systems were evaluated, including animal studies and clinical trials. Liposomes can entrap anticancer drugs and localise their action in the lung following pulmonary delivery. The safety of inhaled liposomes incorporating anticancer drugs depends on the anticancer agent used and the amount of drug delivered to the target cancer in the lung. The difficulty of efficient targeting of liposomal anticancer aerosols to the cancerous tissues within the lung may result in low doses reaching the target site. Overall, following the success of liposomes as inhalable carriers in the treatment of lung infections, it is expected that more focus from research and development will be given to designing inhalable liposome carriers for the treatment of other lung diseases, including pulmonary cancers. The successful development of anticancer liposomes for inhalation may depend on the future development of effective aerosolisation devices and better targeted liposomes to maximise the benefit of therapy and reduce the potential for local and systemic adverse effects.

Roles of EGFR and KRAS and their downstream signaling pathways in pancreatic cancer and pancreatic cancer stem cells

Pancreatic cancer is currently the fourth most common cancer, is increasing in incidence and soon will be the second leading cause of cancer death in the USA. This is a deadly malignancy with an incidence that approximates the mortality with 44,000 new cases and 36,000 deaths each year. Surgery, although only modestly successful, is the only curative option. However, due the locally aggressive nature and early metastasis, surgery can be performed on less than 20% of patients. Cytotoxic chemotherapy is palliative, has significant toxicity and improves survival very little. Thus new treatment paradigms are needed desperately. Due to the extremely high frequency of KRAS gene mutations (>90%) detected in pancreatic cancer patients, the roles of the epidermal growth factor receptor (EGFR), Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTORC1/GSK-3 pathways have been investigated in pancreatic cancer for many years. Constitutively active Ras can activate both of these pathways and there is cross talk between Ras and EGFR which is believed to be important in driving metastasis. Mutant KRAS may also drive the expression of GSK-3 through Raf/MEK/ERK-mediated effects on GSK-3 transcription. GSK-3 can then regulate the expression of NF-kappaB which is important in modulating pancreatic cancer chemoresistance. While the receptors and many downstream signaling molecules have been identified and characterized, there is still much to learn about these pathways and how their deregulation can lead to cancer. Multiple inhibitors to EGFR, PI3K, mTOR, GSK-3, Raf, MEK and hedgehog (HH) have been developed and are being evaluated in various cancers. Current research often focuses on the role of these pathways in cancer stem cells (CSC), with the goal to identify sites where therapeutic resistance may develop. Relatively novel fields of investigation such as microRNAs and drugs used for other diseases e.g., diabetes, (metformin) and malaria (chloroquine) have provided new information about therapeutic resistance and CSCs. This review will focus on recent advances in the field and how they affect pancreatic cancer research and treatment.

Pancreatic cancer: optimizing treatment options, new, and emerging targeted therapies

Pancreatic cancer is the fourth leading cause of cancer death in the US and is expected to become the second leading cause of cancer-related deaths in the next decade. Despite 5-fluorouracil/leucovorin with irinotecan and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel significantly improving outcomes for metastatic cancer, refractory disease still poses significant challenges. Difficulties with early detection and the inherent chemo- and radio-resistant nature of this malignancy led to attempts to define the sequential biology of pancreatic cancer in order to improve survival outcomes. Pancreatic adenocarcinoma is characterized by several germline or acquired genetic mutations, the most common being KRAS (90%), CDK2NA (90%), TP53 (75%-90%), DPC4/SMAD4 (50%). In addition, the tumor microenvironment, chemoresistant cancer stem cells, and the desmoplastic stroma have been the target of some promising clinical investigations. Among the core pathways reproducibly shown to lead the development and progression of this disease, DNA repair, apoptosis, G1/S cell cycle transition, KRAS, Wnt, Notch, Hedgehog, TGF-beta, and other cell invasion pathways, have been the target of "precision therapeutics". No single molecularly targeted therapeutic though has been uniformly successful, probably due to the tumor heterogeneity, but biomarker research is evolving and it hopes to select more patients likely to benefit. Recent reports note activity with immunotherapies such as CD40 agonists, CCR2 inhibitors, cancer vaccines, and novel combinations against the immunosuppressive tumor milieu are ongoing. While many obstacles still exist, clearly we are making progress in deciphering the heterogeneity within pancreatic cancers. Integrating conventional and immunological targeting will be the key to effective treatment of this deadly disease.

Treatment Approaches to Locally Advanced Pancreatic Adenocarcinoma

This article focuses on the management of locally advanced pancreatic cancer, which should be treated as a distinct entity separate from metastatic disease and borderline resectable disease. Although the role, timing, and sequencing of radiation relative to systemic therapy in this disease are controversial, an emerging treatment paradigm involves induction chemotherapy, followed by consolidative chemoradiation in patients who do not progress. In addition, new chemotherapy regimens as well as novel radiosensitizers have shown promise and need to be tested further in the locally advanced setting. Advances in radiotherapy have enabled stereotactic body radiotherapy and should continue to be prospectively evaluated.

S-1 plus gemcitabine chemotherapy followed by concurrent radiotherapy and maintenance therapy with S-1 for unresectable pancreatic cancer

AIM: To investigate the feasibility and efficacy of the combination of S-1 with gemcitabine followed by oral S-1 with concurrent radiotherapy (intensity modulated radiotherapy, IMRT) and maintenance therapy with S-1 for locally advanced pancreatic cancer.

METHODS: Subjects selected in the study were patients who had unresectable and locally advanced pancreatic cancer without distant metastases, adequate organ and marrow functions, an Eastern Cooperative Oncology Group performance status of 0-1 and no prior anticancer therapy. Initially the subjects received two cycles of chemotherapy, oral administration of S-1 40 mg/m² twice daily from day 1 to day 14 of a 21-d cycle, with 30-min intravenous infusions of gemcitabine 1000 mg/m² on day 1 and day 8. Two weeks after the completion of chemotherapy, S-1 was administered orally with concurrent IMRT. Oral S-1 was administered at a dose of 80 mg/m² per day twice daily from day 1 to day 14 and from day 22 to day 35. Radiation was concurrently delivered at a dose of 50.4 Gy (1.8 Gy/d, 5 times per week, 28 fractions). One month after the completion of chemotherapy and radiotherapy, S-1 was administered orally at a dose of 80 mg/m² per day twice daily for 14 d, followed by a 14-d rest period. This cycle was repeated as maintenance therapy, until unacceptable toxicity occurred or the disease worsened. Thirty-two patients were involved in this study. The median follow-up was 15.6 mo (range: 8.6-32.3 mo).

RESULTS: Thirty-two patients completed the scheduled course of chemotherapy, while 30 patients (93.8%) received chemoradiotherapy with two patients ceasing to continue with radiotherapy. The major toxic effects were nausea and leukopenia. There was no grade 4 toxicity or treatment-related death. According to the Response Evaluation Criteria in Solid Tumors criteria, the objective tumor response was partial response in 17 (53.1%) patients, stable disease in 9 (28.1%), and progressive disease in 6 (18.8%). The median overall survival and median progression-free survival were 15.2 mo and 9.3 mo, respectively. The survival rates at 1 year and 2 years were 75% and 34.4%, respectively.

CONCLUSION: The combination of S-1 with gemcitabine followed by oral S-1 with IMRT and maintenance therapy with S-1 alone in patients with locally advanced pancreatic cancer may be considered a well-tolerated, promising treatment regimen.

Lessons learned from radiation oncology clinical trials

A workshop entitled "Lessons Learned from Radiation Oncology Trials" was held on December 7-8, 2011, in Bethesda, MD, to present and discuss some of the recently conducted radiation oncology clinical trials with a focus on those that failed to refute the null hypothesis. The objectives of this workshop were to summarize and examine the questions that these trials provoked, to assess the quality and limitations of the preclinical data that supported the hypotheses underlying these trials, and to consider possible solutions to these challenges for the design of future clinical trials. Several themes emerged from the discussions: (i) opportunities to learn from null-hypothesis trials through tissue and imaging studies; (ii) value of preclinical data supporting the design of combinatorial therapies; (iii) significance of validated biomarkers; (iv) necessity of quality assurance in radiotherapy delivery; (v) conduct of sufficiently powered studies to address the central hypotheses; and (vi) importance of publishing results of the trials regardless of the outcome. The fact that well-designed hypothesis-driven clinical trials produce null or negative results is expected given the limitations of trial design and complexities of cancer biology. It is important to understand the reasons underlying such null results, however, to effectively merge the technologic innovations with the rapidly evolving biology for maximal patient benefit through the design of future clinical trials.

Recent progress in pancreatic cancer

Pancreatic cancer is currently one of the deadliest of the solid malignancies. However, surgery to resect neoplasms of the pancreas is safer and less invasive than ever, novel drug combinations have been shown to improve survival, advances in radiation therapy have resulted in less toxicity, and enormous strides have been made in the understanding of the fundamental genetics of pancreatic cancer. These advances provide hope but they also increase the complexity of caring for patients. It is clear that multidisciplinary care that provides comprehensive and coordinated evaluation and treatment is the most effective way to manage patients with pancreatic cancer.

Recent progress in pancreatic cancer

Pancreatic cancer is currently one of the deadliest of the solid malignancies. However, surgery to resect neoplasms of the pancreas is safer and less invasive than ever, novel drug combinations have been shown to improve survival, advances in radiation therapy have resulted in less toxicity, and enormous strides have been made in the understanding of the fundamental genetics of pancreatic cancer. These advances provide hope but they also increase the complexity of caring for patients. It is clear that multidisciplinary care that provides comprehensive and coordinated evaluation and treatment is the most effective way to manage patients with pancreatic cancer.

Compliance with therapeutic guidelines in Radiation Therapy Oncology Group prospective gastrointestinal clinical trials

BACKGROUND

This report analyzes the adherence to radiation therapy protocol guidelines in contemporary Radiation Therapy Oncology Group (RTOG) gastrointestinal trials. We aim to provide insight into current standards and compliance of radiation therapy field design and administration.

METHODS

From 1994 to 2006, the Gastrointestinal Cancer Committee of the RTOG initiated and completed 15 phase I-III clinical trials utilizing radiation therapy in the multimodality treatment of gastrointestinal cancers. In each protocol, details for planning and executing radiation therapy were outlined and each protocol contained scoring criteria for these components of radiation therapy, characterized according to per-protocol, variation acceptable and deviation unacceptable. Review of treatment planning and implementation was performed in all studies following therapy completion.

RESULTS

Radiation therapy planning and implementation was reviewed in 2309 of 2312 (99.9%) patients. The mean rate of compliance over all for the 15 protocols was 65% (total of the 2309 analyzed patients). The mean variation acceptable rate was 21% whereas the mean deviation unacceptable rate was 5%. The mean "other" rate (no RT given or incomplete RT due to death, progression or refusal) was 8%. Two of the 15 trials (13%) had deviation unacceptable rates >10%. In four studies incorporating pre-treatment review of radiation therapy planning and treatment, compliance with protocol therapy was enhanced.

CONCLUSIONS

The fidelity of radiation planning and execution detailed in protocol to actual therapy is heterogeneous, with a mean per-protocol rate of 65%. As clinical trials evolve, available technology should permit efficient pre-treatment review processes, thus facilitating compliance to protocol therapy. These analyses should also permit prospective analysis of outcome measures by compliance to therapy.