Future directions in drug development in pancreatic cancer

Pancreatic cancer is still one of the most lethal cancers with a reported 5-year relative survival rate of approximatively 9% and medical treatment remains a major challenge. Systemic treatment is recommended in every setting: resectable, borderline resectable, locally advanced and metastatic. Yet, few groundbreaking changes in practice have occurred in the last 30 years compared to other cancers and new treatments options are highly desirable. Most treatment approaches using chemotherapy have failed to improve patients' life expectancy and the few therapies finally found to have statistically significant benefit actually have modest clinical impact. It is becoming imperative to find new paths for improvement, such as encapsulated agents, new generation targeted therapies and treatments directed against the tumor microenvironment. We report here the new drugs of interest in pancreatic cancer and analyze the most recent failures.

The Match between Molecular Subtypes, Histology and Microenvironment of Pancreatic Cancer and Its Relevance for Chemoresistance

In the last decade, several studies based on whole transcriptomic and genomic analyses of pancreatic tumors and their stroma have come to light to supplement histopathological stratification of pancreatic cancers with a molecular point-of-view. Three main molecular studies: Collisson et al. 2011, Moffitt et al. 2015 and Bailey et al. 2016 have found specific gene signatures, which identify different molecular subtypes of pancreatic cancer and provide a comprehensive stratification for both a personalized treatment or to identify potential druggable targets. However, the routine clinical management of pancreatic cancer does not consider a broad molecular analysis of each patient, due probably to the lack of target therapies for this tumor. Therefore, the current treatment decision is taken based on patients´ clinicopathological features and performance status. Histopathological evaluation of tumor samples could reveal many other attributes not only from tumor cells but also from their microenvironment specially about the presence of pancreatic stellate cells, regulatory T cells, tumor-associated macrophages, myeloid derived suppressor cells and extracellular matrix structure. In the present article, we revise the four molecular subtypes proposed by Bailey et al. and associate each subtype with other reported molecular subtypes. Moreover, we provide for each subtype a potential description of the tumor microenvironment that may influence treatment response according to the gene expression profile, the mutational landscape and their associated histology.

Stereotactic Body Radiation Therapy (SBRT) Combined With Chemotherapy for Unresected Pancreatic Adenocarcinoma

Objectives:

The role of radiation therapy in the management of unresectable pancreatic cancer is controversial. One concern about concurrent chemoradiation relates to the timing of chemotherapy. In contrast to conventional radiation therapy, stereotactic body radiation therapy (SBRT) delivers high doses in a shorter duration resulting in minimal disruption in chemotherapy. Here, we report our results of patients treated with SBRT and chemotherapy for inoperable pancreatic cancer.

Materials and Methods:

Thirty-eight patients treated with SBRT and chemotherapy for locally advanced, borderline resectable, and medically inoperable pancreatic cancer at our institution from January 2008 to December 2012 were included in this retrospective analysis. Treatment was delivered in 5 fractions of 5 or 6 Gy per fraction over 5 days. Toxicities were scored using the Common Terminology Criteria for Adverse Events version 3. Survival was calculated using the Kaplan-Meier method.

Results:

The median age was 70 years (range, 45 to 90 y). Eastern Cooperative Oncology Group performance status ranged from 0 to 3. Thirty-four patients received concurrent chemotherapy. Four patients received sequential chemotherapy. Median overall survival was 14.3 months and median progression-free survival was 9.2 months from diagnosis. From radiation, overall survival and progression-free survival were 12.3 and 6.8 months, respectively. The overall local control rate was 79%. Acute toxicity was minimal. Severe late SBRT-related toxicities included 1 grade 3 gastric outlet obstruction, 1 grade 4 biliary stricture, and 1 grade 5 gastric hemorrhage.

Conclusions:

SBRT combined with chemotherapy for unresectable pancreatic cancer is convenient, feasible, and generally well tolerated. Outcomes of SBRT combined with chemotherapy compare favorably to results obtained with chemotherapy and conventional radiation therapy.

Tumor Reduction in Primary and Metastatic Pancreatic Cancer Lesions With nab-Paclitaxel and Gemcitabine: An Exploratory Analysis From a Phase 3 Study

OBJECTIVES

Results from the phase 3 Metastatic Pancreatic Adenocarcinoma Clinical Trial (MPACT) led to approval of nab-paclitaxel plus gemcitabine for first-line treatment of metastatic pancreatic cancer. The current analysis evaluated the effects of nab-paclitaxel plus gemcitabine versus gemcitabine on primary pancreatic and metastatic lesions.

METHODS

In this analysis of the previously described MPACT trial, changes in pancreatic and metastatic tumor burden were assessed using independently measured diameters of lesions on computed tomography or magnetic resonance imaging scans. Changes in the sums of longest tumor diameters were summarized using descriptive statistics and were included in a multivariate analysis of overall survival.

RESULTS

Primary pancreatic lesion measurement was feasible. Reductions in primary pancreatic tumor burden and metastatic burden from baseline to nadir were significantly greater with nab-paclitaxel plus gemcitabine versus gemcitabine. Baseline pancreatic tumor burden was independently predictive of survival. Both regimens elicited linear reductions in primary pancreatic and metastatic tumor burden through time. There was a high within-patient concordance of tumor changes between primary pancreatic lesions and metastatic lesions.

CONCLUSIONS

This analysis of MPACT demonstrated significant tumor shrinkage benefit for nab-paclitaxel plus gemcitabine in both primary pancreatic and metastatic lesions, supporting ongoing evaluation of this regimen in locally advanced disease.

Preoperative FOLFIRINOX for borderline resectable pancreatic cancer: Is radiation necessary in the modern era of chemotherapy?

BACKGROUND

No consensus exists regarding the optimal neoadjuvant treatment paradigm for patients with borderline resectable pancreatic cancer (BRPC), including the respective roles of chemotherapy and radiation.

METHODS

We performed a retrospective analysis, including detailed pathologic and radiologic review, of pancreatic cancer patients undergoing FOLFIRINOX, with or without radiation therapy (RT), prior to surgical resection at a high-volume academic center over a 4-year period.

RESULTS

Of 26 patients meeting inclusion criteria, 22 (84.6%) received FOLFIRINOX alone without RT (median number of treatment cycles = 9). The majority of patients met formal radiographic criteria for BRPC, with the superior mesenteric vein representing the most common vessel involved. R0 resection rate was 90.9%, with 12 patients (54.5%) requiring vascular reconstruction. Treatment response was classified as moderate or marked in 16 patients (72.7%) according to the College of American Pathologists grading system. Estimated median disease-free and overall survival rates are 22.6 months and not reached (NR), respectively.

CONCLUSIONS

This is one of the largest series to describe the use of neoadjuvant FOLFIRINOX, without radiation therapy, in patients with BRPC undergoing surgical resection. Given the high R0 resection rates and favorable clinical outcomes with chemotherapy alone, this strategy should be further assessed in prospective study design. J. Surg. Oncol. 2016;114:587-596. © 2016 Wiley Periodicals, Inc.

Iontophoretic device delivery for the localized treatment of pancreatic ductal adenocarcinoma

Poor delivery and systemic toxicity of many cytotoxic agents, such as the recent promising combination chemotherapy regimen of folinic acid (leucovorin), fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX), restrict their full utility in the treatment of pancreatic cancer. Local delivery of chemotherapies has become possible using iontophoretic devices that are implanted directly onto pancreatic tumors. We have fabricated implantable iontophoretic devices and tested the local iontophoretic delivery of FOLFIRINOX for the treatment of pancreatic cancer in an orthotopic patient-derived xenograft model. Iontophoretic delivery of FOLFIRINOX was found to increase tumor exposure by almost an order of magnitude compared with i.v. delivery with substantially lower plasma concentrations. Mice treated for 7 wk with device FOLFIRINOX experienced significantly greater tumor growth inhibition compared with i.v. FOLFIRINOX. A marker of cell proliferation, Ki-67, was stained, showing a significant reduction in tumor cell proliferation. These data capitalize on the unique ability of an implantable iontophoretic device to deliver much higher concentrations of drug to the tumor compared with i.v. delivery. Local iontophoretic delivery of cytotoxic agents should be considered for the treatment of patients with unresectable nonmetastatic disease and for patients with the need for palliation of local symptoms, and may be considered as a neoadjuvant approach to improve resection rates and outcome in patients with localized and locally advanced pancreatic cancer.

Current controversies in the stage-specific multidisciplinary management of pancreatic cancer

Encouraging therapeutic approaches and treatment regimens for patients with both localized and metastatic pancreatic cancer have emerged over the last 5 years. However, these new strategies have brought important challenges and controversy. Clinical staging criteria are constantly evolving. No system has been uniformly adopted, limiting our understanding of the role of both pancreatectomy and neoadjuvant therapies for localized disease. The role of radiation therapy for the treatment of both resectable and unresectable pancreatic cancer remains unclear despite multiple prospective studies. Although two new systemic chemotherapy regimens have essentially transformed the care of many patients with metastatic cancer, criteria to guide their use in the general population have yet to be clearly established. Herein we provide an overview of these important controversies in the context of a broad update on the stage-specific management of patients with newly diagnosed pancreatic cancer.

Full dose neoadjuvant FOLFIRINOX is associated with prolonged survival in patients with locally advanced pancreatic adenocarcinoma

BACKGROUND

The efficacy of FOLFIRINOX for metastatic pancreatic cancer has led to its use in patients with earlier stages of disease. This study retrospectively analyzed a cohort of patients with locally-advanced pancreatic cancer (LAPC) treated with FOLFIRINOX.

METHODS

Between 2008 and 2013, 51 treatment-naïve patients with LAPC at a single institution received first-line FOLFIRINOX with neoadjuvant intent, at the full dose as described in the PRODIGE 4/ACCORD 11 study. Combined chemoradiation was administered for those who remained unresectable after maximum response to chemotherapy. The primary outcome measure was overall survival (OS), and secondary outcomes were progression-free survival (PFS) and margin-negative (R0) resection rate, and toxicity profile.

RESULTS

A total of 429 cycles of FOLFIRINOX were given with a median of 8 cycles (range 2-29) per patient; 66% of cycles were full dose. After chemotherapy, 27 (53%) received chemoradiation. The median OS was 35.4 months (95% CI 25.8-45). Ten (4 borderline resectable and 6 unresectable) patients had successful R0 resections; those who had R0 resections had a significantly longer survival than those who did not (3-year OS rate 67% versus 21%, log rank p = 0.042). Increasing number of full-dose cycles was significantly associated with increased survival. The toxicity profile was similar to previous reports of this regimen.

CONCLUSIONS

FOLFIRINOX is feasible as neoadjuvant therapy for LAPC. Although the R0 resection rate was only 20%, the median OS of almost 3 years appears promising. Dose intensity and duration were associated with increased survival in this study, arguing against dose attenuated versions of this regimen.

Prognostic factors and sites of metastasis in unresectable locally advanced pancreatic cancer

Due to differences in natural history and therapy, clinical trials of patients with advanced pancreatic cancer have recently been subdivided into unresectable locally advanced pancreatic cancer (LAPC) and metastatic disease. We aimed to evaluate prognostic factors in LAPC patients who were treated with first-line chemotherapy and describe patterns of disease progression. Patients with LAPC who initiated first-line palliative chemotherapy, 2001–2011 at the BC Cancer Agency were included. A retrospective chart review was conducted to identify clinicopathologic variables, treatment, and subsequent sites of metastasis. Kaplan–Meier and Cox-regression survival analyses were performed. A total of 244 patients were included in this study. For the majority of patients (94.3%), first-line therapy was single-agent gemcitabine. About 144 (59%) patients developed distant metastatic disease and the most frequent metastatic sites included peritoneum/omentum (42.3%), liver (41%), lungs (13.9%), and distant lymph nodes (9%). Median overall survival (OS) for the entire cohort was 11.7 months (95% CI, 10.6–12.8). Development of distant metastases was associated with significantly inferior survival (HR 3.56, 95% CI 2.57–4.93), as was ECOG 2/3 versus 0/1 (HR 1.69, 95% CI 1.28–2.23), CA 19.9 > 1000 versus ≤1000 (HR 1.59, 95% CI 1.19–2.14) and female gender, (HR 1.57, 95% CI 1.19–2.08). In this population-based study, 41% of LAPC patients treated with first-line chemotherapy died without evidence of distant metastases. Prognostic factors for LAPC were baseline performance status, elevated CA 19.9, gender, and development of distant metastasis. Results highlight the heterogeneity of LAPC and the importance of locoregional tumor control.

Ductal pancreatic adenocarcinoma

BACKGROUND

Ductal adenocarcinoma of the pancreas is the fourth most common cause of death from cancer in men and women in Germany: about 15 000 persons die of this disease each year.

METHOD

The S3 guideline on exocrine pancreatic carcinoma was updated with the aid of systematic literature reviews on the surgical, neoadjuvant, and adjuvant treatment of ductal pancreatic carcinoma, and on treatment in the metastatic stage. These reviews covered the periods 2002 to February 2012 (for radiotherapy) and 2006 to August 2011 (for all other topics).

RESULTS

The criteria for borderline resectable pancreatic tumors are the same as those of the guidelines of the National Comprehensive Cancer Network. Preoperative biliary drainage with a stent is recommended only if cholangitis is present or if a planned operation cannot be performed soon after the diagnosis is made. When a pancreatic carcinoma is resected, at least 10 regional lymph nodes should be excised, and the ratio of affected to excised nodes should be documented in the pathology report. Gemcitabine and 5-fluorouracil are recommended for adjuvant therapy. Neither of these drugs is preferred over the other; if the one initially given is poorly tolerated, the other one should be given instead. When gemcitabine and erlotinib are given for palliative treatment, erlotinib should be given for no longer than 8 weeks if no skin rash develops. In selected patients, the folfirinox protocol yields markedly better results than gemcitabin. Moreover, the new combination of nab-paclitaxel and gemcitabine can be used as first-line treatment. In the event of disease progression under first-line treatment, second-line treatment should be initiated.

CONCLUSION

In recent years, new chemotherapeutic protocols have brought about marked improvement in palliative care. Further trials are needed to determine whether the perioperative or adjuvant use of these protocols might also improve the outcome of surgical treatment with curative intent.