A phase I/II trial of intensity modulated radiation (IMRT) dose escalation with concurrent fixed-dose rate gemcitabine (FDR-G) in patients with unresectable pancreatic cancer

[Neoadjuvant treatment for unresectable pancreatic tumors: Against!]

Should we consider surgery for pancreatic cancer when resectability seems initially uncertain? The answer is no consensual as illustrated by the controversy presented here. This article presents the key arguments against surgery.

Pancreatic cancer and SBRT: A new potential option?

Local control remains a major issue for patients with unresectable, locally advanced pancreatic cancer (LAPC). The role of radiation therapy in the management of LAPC represents an area of some controversy. Stereotactic body radiotherapy is an emerging treatment option for LAPC as it can provide a therapeutic benefit with significant advantages for patients' quality of life over standard conventional chemoradiation. The objective of this review is to present the rationale for stereotactic body radiotherapy in LAPC, as well as to discuss the potential limitations and caveats of the currently available studies.

Targeting mcl-1 for radiosensitization of pancreatic cancers

In order to identify targets whose inhibition may enhance the efficacy of chemoradiation in pancreatic cancer, we previously conducted an RNAi library screen of 8,800 genes. We identified Mcl-1 (myeloid cell leukemia-1), an anti-apoptotic member of the Bcl-2 family, as a target for sensitizing pancreatic cancer cells to chemoradiation. In the present study we investigated Mcl-1 inhibition by either genetic or pharmacological approaches as a radiosensitizing strategy in pancreatic cancer cells. Mcl-1 depletion by siRNA produced significant radiosensitization in BxPC-3 and Panc-1 cells in association with Caspase-3 activation and PARP cleavage, but only minimal radiosensitization in MiaPaCa-2 cells. We next tested the ability of the recently identified, selective, small molecule inhibitor of Mcl-1, UMI77, to radiosensitize in pancreatic cancer cells. UMI77 caused dissociation of Mcl-1 from the pro-apoptotic protein Bak and produced significant radiosensitization in BxPC-3 and Panc-1 cells, but minimal radiosensitization in MiaPaCa-2 cells. Radiosensitization by UMI77 was associated with Caspase-3 activation and PARP cleavage. Importantly, UMI77 did not radiosensitize normal small intestinal cells. In contrast, ABT-737, an established inhibitor of Bcl-2, Bcl-XL, and Bcl-w, failed to radiosensitize pancreatic cancer cells suggesting the unique importance of Mcl-1 relative to other Bcl-2 family members to radiation survival in pancreatic cancer cells. Taken together, these results validate Mcl-1 as a target for radiosensitization of pancreatic cancer cells and demonstrate the ability of small molecules which bind the canonical BH3 groove of Mcl-1, causing displacement of Mcl-1 from Bak, to selectively radiosensitize pancreatic cancer cells.

Phase 2 multi-institutional trial evaluating gemcitabine and stereotactic body radiotherapy for patients with locally advanced unresectable pancreatic adenocarcinoma

Background

This phase 2 multi-institutional study was designed to determine whether gemcitabine (GEM) with fractionated stereotactic body radiotherapy (SBRT) results in acceptable late grade 2 to 4 gastrointestinal toxicity when compared with a prior trial of GEM with single-fraction SBRT in patients with locally advanced pancreatic cancer (LAPC).

Methods

A total of 49 patients with LAPC received up to 3 doses of GEM (1000 mg/m²) followed by a 1-week break and SBRT (33.0 gray [Gy] in 5 fractions). After SBRT, patients continued to receive GEM until disease progression or toxicity. Toxicity was assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0] and the Radiation Therapy Oncology Group radiation morbidity scoring criteria. Patients completed the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and pancreatic cancer-specific QLQ-PAN26 module before SBRT and at 4 weeks and 4 months after SBRT.

Results

The median follow-up was 13.9 months (range, 3.9-45.2 months). The median age of the patients was 67 years and 84% had tumors of the pancreatic head. Rates of acute and late (primary endpoint) grade ≥2 gastritis, fistula, enteritis, or ulcer toxicities were 2% and 11%, respectively. QLQ-C30 global quality of life scores remained stable from baseline to after SBRT (67 at baseline, median change of 0 at both follow-ups; P>.05 for both). Patients reported a significant improvement in pancreatic pain (P = .001) 4 weeks after SBRT on the QLQ-PAN26 questionnaire. The median plasma carbohydrate antigen 19-9 (CA 19-9) level was reduced after SBRT (median time after SBRT, 4.2 weeks; 220 U/mL vs 62 U/mL [P<.001]). The median overall survival was 13.9 months (95% confidence interval, 10.2 months-16.7 months). Freedom from local disease progression at 1 year was 78%. Four patients (8%) underwent margin-negative and lymph node-negative surgical resections.

Conclusions

Fractionated SBRT with GEM results in minimal acute and late gastrointestinal toxicity. Future studies should incorporate SBRT with more aggressive multiagent chemotherapy.

To the authors' knowledge, the current study is the first prospective multi-institutional trial evaluating the role of stereotactic body radiotherapy in patients with locally advanced pancreatic cancer. The results suggest that fractionated stereotactic body radiotherapy with gemcitabine achieves favorable toxicity, quality of life, and preliminary efficacy compared with historical data.

Utilization of intensity-modulated radiation therapy and image-guided radiation therapy in pancreatic cancer: is it beneficial?

The recent development of intensity-modulated radiation therapy (IMRT) and improvements in image-guided radiotherapy (IGRT) have provided considerable advances in the utilization of radiation therapy (RT) for the management of pancreatic cancer. IGRT allows for the reduction of treatment volumes, potentially less chance of a marginal miss, and quality assurance of gastrointestinal filling, while IMRT has been shown to reduce both sudden and late side effects compared with 3-dimensional conformal RT. Here, we review published data and provide essential recommendations on the utilization of IMRT and IGRT for the management of patients with pancreatic cancer.

Management of borderline resectable pancreatic cancer

Borderline resectable pancreatic cancers are those that, although technically resectable, are at high risk for margin-positive resection following surgery de novo. Generally, such cancers are characterized by localized primary tumors that involve the mesenteric vasculature to a limited degree and that may require venous or hepatic arterial resection at pancreatectomy. In this article, we review diagnosis and staging algorithms, pretreatment strategies, and multidisciplinary treatment protocols for patients with this stage of disease. The rationale for and results following treatment with neoadjuvant chemotherapy and chemoradiation and subsequent surgical resection of the primary tumor are described in detail and existing data are reviewed.

Management options in locally advanced pancreatic cancer

Pancreatic ductal adenocarcinoma is a highly lethal cancer that is rarely curable at the time of presentation. Unfortunately, most patients are diagnosed with either metastatic or locally advanced disease, which is not amenable to surgery owing to the high likelihood of incomplete resection. Given the generally poor prognosis with propensity for metastatic failure greater than that for local failure, treatment options are variable, and include chemotherapy, radiotherapy, targeted therapies, and combinations thereof. This review summarizes the current evidence for definitive management of locally advanced pancreatic adenocarcinoma, as well as the role of palliative therapies. Future directions, including the development of predictive biomarkers and novel systemic agents, are also discussed.

Stereotactic body radiation therapy in pancreatic cancer: the new frontier

Pancreatic cancer (PCA) remains a disease with a poor prognosis. The majority of PCA patients are unable to undergo surgical resection, which is the only potentially curative option at this time. A combination of chemotherapy and chemoradiation (CRT) are standard options for patients with locally advanced, unresectable disease, however, local control and patient outcomes remains poor. Stereotactic body radiation therapy (SBRT) is an emerging treatment option for PCA. SBRT delivers potentially ablative doses to the pancreatic tumor plus a small margin over a short period of time. Early studies with single-fraction SBRT demonstrated excellent tumor control with high rates of toxicity. The implementation of SBRT (3-5 doses) has demonstrated promising outcomes with favorable tumor control and toxicity rates. Herein we discuss the evolving role of SBRT in PCA treatment.

Locally advanced pancreatic cancer: the role of definitive chemoradiotherapy

At the time of diagnosis, around 20% of patients with pancreatic cancer present at a resectable stage, 50% have metastatic disease and 30% have locally advanced tumour, non-metastatic but unresectable because of superior mesenteric artery or coeliac encasement. Despite advances in chemoradiotherapy and improved systemic chemotherapeutic agents, patients with locally advanced pancreatic cancer suffer from high rates of distant metastatic failure and from local progression, with a median survival time ranging from 5 to 11 months. In the past 30 years, modest improvements in median survival have been attained for these patients treated by chemoradiotherapy or chemotherapy protocols. The optimal therapy for patients with locally advanced pancreatic carcinoma remains controversial. This review aims to evaluate the role of radiotherapy for these patients.

Role of chemoradiotherapy in the adjuvant and neoadjuvant settings for resectable pancreatic cancer

Pancreatic cancer is the 10th most commonly diagnosed malignancy in the USA and the fourth most common cause of cancer-related death. Worldwide, the mortality incidence ratio approaches 98%. Although only 15-20% of patients present with resectable disease, there is international consensus that complete surgical resection (R0, i.e. grossly and microscopically negative margins) is a vital part of any curative treatment paradigm. Despite advances in surgical technique, peri-operative care, chemotherapy and radiation delivery techniques over the past two decades, 5 year overall survival rates for resected pancreatic cancer with modern therapies remain around 20-25%. There is level I evidence for adjuvant chemotherapy in fully resected pancreatic cancer, but randomised trials examining the role of adjuvant chemoradiotherapy to date do not provide clear support for radiation therapy in this setting. In addition, efforts to increase the proportion of long-term survivors have recently centred on increasing the resectability of locoregional disease by incorporating neoadjuvant treatment before definitive surgery. Post-hoc analysis of randomised data as well as retrospective reviews have shown that there are several independent prognostic factors that may have considerable impact on survival outcomes, complicating interpretation and comparison of historical data. There is considerable interest in adjuvant and neoadjuvant therapy, but there is significant controversy as to whether radiation is of value, especially in the adjuvant context. Herein, we explore the sources of those controversies.

Combined inhibition of Wee1 and PARP1/2 for radiosensitization in pancreatic cancer

PURPOSE

While the addition of radiation to chemotherapy improves survival in patients with locally advanced pancreatic cancer, more effective therapies are urgently needed. Thus, we investigated the radiosensitizing efficacy of the novel drug combination of Wee1 and PARP1/2 inhibitors (AZD1775 and olaparib, respectively) in pancreatic cancer.

EXPERIMENTAL DESIGN

Radiosensitization of AsPC-1 or MiaPaCa-2 human pancreatic cancer cells was assessed by clonogenic survival and tumor growth assays. Mechanistically, the effects of AZD1775, olaparib, and radiation on cell cycle, DNA damage (γH2AX), and homologous recombination repair (HRR) were determined.

RESULTS

Treatment of AsPC-1 and MiaPaCa-2 cells with either AZD1775 or olaparib caused modest radiosensitization, whereas treatment with the combination significantly increased radiosensitization. Radiosensitization by the combination of AZD1775 and olaparib was associated with G2 checkpoint abrogation and persistent DNA damage. In addition, AZD1775 inhibited HRR activity and prevented radiation-induced Rad51 focus formation. Finally, in vivo, in MiaPaCa-2-derived xenografts, olaparib did not radiosensitize, whereas AZD1775 produced moderate, yet significant, radiosensitization (P < 0.05). Importantly, the combination of AZD1775 and olaparib produced highly significant radiosensitization (P < 0.0001) evidenced by a 13-day delay in tumor volume doubling (vs. radiation alone) and complete eradication of 20% of tumors.

CONCLUSIONS

Taken together, these results demonstrate the efficacy of combined inhibition of Wee1 and PARP inhibitors for radiosensitizing pancreatic cancers and support the model that Wee1 inhibition sensitizes cells to PARP inhibitor-mediated radiosensitization through inhibition of HRR and abrogation of the G2 checkpoint, ultimately resulting in unrepaired, lethal DNA damage and radiosensitization. Clin Cancer Res; 20(19); 5085-96. ©2014 AACR.

Adaptive dose-finding studies: a review of model-guided phase I clinical trials

PURPOSE

We provide a comprehensive review of adaptive phase I clinical trials in oncology that used a statistical model to guide dose escalation to identify the maximum-tolerated dose (MTD). We describe the clinical setting, practical implications, and safety of such applications, with the aim of understanding how these designs work in practice.

METHODS

We identified 53 phase I trials published between January 2003 and September 2013 that used the continual reassessment method (CRM), CRM using escalation with overdose control, or time-to-event CRM for late-onset toxicities. Study characteristics, design parameters, dose-limiting toxicity (DLT) definition, DLT rate, patient-dose allocation, overdose, underdose, sample size, and trial duration were abstracted from each study. In addition, we examined all studies in terms of safety, and we outlined the reasons why escalations occur and under what circumstances.

RESULTS

On average, trials accrued 25 to 35 patients over a 2-year period and tested five dose levels. The average DLT rate was 18%, which is lower than in previous reports, whereas all levels above the MTD had an average DLT rate of 36%. On average, 39% of patients were treated at the MTD, and 74% were treated at either the MTD or an adjacent level (one level above or below).

CONCLUSION

This review of completed phase I studies confirms the safety and generalizability of model-guided, adaptive dose-escalation designs, and it provides an approach for using, interpreting, and understanding such designs to guide dose escalation in phase I trials.

Challenges in using ¹⁸F-fluorodeoxyglucose-PET-CT to define a biological radiotherapy boost volume in locally advanced pancreatic cancer

BACKGROUND

The best method of identifying regions within pancreatic tumours that might benefit from an increased radiotherapy dose is not known. We investigated the utility of pre-treatment FDG-PET in predicting the spatial distribution of residual metabolic activity following chemoradiotherapy (CRT) in locally advanced pancreatic cancer (LAPC).

METHODS

17 patients had FDG-PET/CT scans at baseline and six weeks post-CRT. Tumour segmentation was performed at 40% and 50% of SUVmax at baseline and 60%, 70%, 80% and 90% post-CRT. FDG-PET scans were non-rigidly registered to the radiotherapy planning CT using the CT component of the FDG-PET/CT. Percentage overlap of the post-CRT volumes with the pre-CRT volumes with one another and the gross tumour volume (GTV) was calculated.

RESULTS

SUVmax decreased during CRT (median pre- 8.0 and post- 3.6, p < 0.0001). For spatial correlation analysis, 9 pairs of scans were included (Four were excluded following complete metabolic response, one patient had a non-FDG avid tumour, one had no post-CRT imaging, one had diffuse FDG uptake that could not be separated from normal tissues and one had an elevated blood glucose). The Pre40% and 50% of SUVmax volumes covered a mean of 50.8% and 30.3% of the GTV respectively. The mean% overlap of the 90%, 80%, 70%, 60% of SUVmax post-CRT with the Pre40% and Pre50% volumes were 83.3%, 84.0%, 83.7%, 77.9% and 77.8%, 69.9%, 74.5%, 64.8% respectively.

CONCLUSIONS

Regions of residual metabolic activity following CRT can be predicted from the baseline FDG-PET and could aid definition of a biological target volume for non-uniform dose prescriptions.

Radiosensitization of Pancreatic Cancer Cells In Vitro and In Vivo through Poly (ADP-ribose) Polymerase Inhibition with ABT-888

OBJECTIVES

To determine whether poly (ADP-ribose) polymerase-1/2 (PARP-1/2) inhibition enhances radiation-induced cytotoxicity of pancreatic adenocarcinoma in vitro and in vivo, and the mechanism by which this occurs.

METHODS

Pancreatic carcinoma cells were treated with ABT-888, radiation, or both. In vitro cell viability, apoptosis, and PARP activity were measured. Orthotopic xenografts were generated in athymic mice and treated with ABT-888 (25mg/kg), radiation (5Gy), both, or no treatment. Mice were monitored with bioluminescence imaging.

RESULTS

In vitro, treatment with ABT-888 and radiation led to higher rates of cell death after 8days (P < .01). Co-treatment with 5Gy and 1, 10 or 100μmol/l of ABT-888 led to dose enhancement factors of 1.29, 1.41 and 2.36, respectively. Caspase activity was not significantly increased when treated with ABT-888 (10 μmol/l) alone (1.28-fold, P = .08), but became significant when radiation was added (2.03-fold, P < .01). PARP activity increased post-radiation and was abrogated following co-treatment with ABT-888. In vivo, treatment with ABT-888, radiation or both led to tumor growth inhibition (TGI) of 8, 30 and 39days, and survival at 60days of 0%, 0% and 40%, respectively.

CONCLUSIONS

ABT-888 with radiation significantly enhanced tumor response in vitro and in vivo. ABT-888 inhibited PAR protein polymerization resulting in dose-dependent feedback up-regulation of PARP and p-ATM suggesting increased DNA damage. This translated into enhancement in TGI and survival with radiation in vivo. In vitro PAR levels correlated with levels of tumor apoptosis suggesting potential as a predictive biomarker. These data are being used to support a Phase I study in locally advanced pancreatic cancer.

The influence of radiation therapy dose escalation on overall survival in unresectable pancreatic adenocarcinoma

PURPOSE

Radiation therapy (RT) dose escalation in unresectable pancreatic adenocarcinoma (PAC) remains investigational. We examined the association between total RT dose and overall survival (OS) in patients with unresectable PAC.

METHODS AND MATERIALS

National cancer data base (NCDB) data were obtained for patients who underwent definitive chemotherapy and RT (chemo-RT) for unresectable PAC. Univariate (UV) and multivariate (MV) survival analysis were performed along with Kaplan-Meier (KM) estimates for incremental RT dose levels.

RESULTS

A total of 977 analyzable patients met inclusion criteria. Median tumor size was 4.0 cm (0.3-40 cm) and median RT dose was 45 Gy. Median OS was 10 months (95% CI, 9-10 months). On MV analysis RT dose <30 Gy [HR, 2.38 (95% CI, 1.85-3.07); P<0.001] and RT dose ≥30 to <40 Gy [HR, 1.41 (95% CI, 1.04-1.91); P=0.026] were associated with lower OS when compared with dose ≥55 Gy. Patients receiving RT doses from 40 to <45, 45 to <50, 50 to <55, and ≥55 Gy did not differ in OS.

CONCLUSIONS

Lack of benefit to OS with conventionally delivered RT above 40 Gy is shown. Optimal RT dose escalation methods in unresectable PAC remain an important subject for investigation in prospective clinical trials.

Effect of cytotoxic chemotherapy on markers of molecular age in patients with breast cancer

BACKGROUND

Senescent cells, which express p16 (INK4a) , accumulate with aging and contribute to age-related pathology. To understand whether cytotoxic agents promote molecular aging, we measured expression of p16 (INK4a) and other senescence markers in breast cancer patients treated with adjuvant chemotherapy.

METHODS

Blood and clinical information were prospectively obtained from 33 women with stage I to III breast cancer at four time points: before anthracycline-based chemotherapy, immediately after anthracycline-based chemotherapy, 3 months after anthracycline-based chemotherapy, and 12 months after anthracycline-based chemotherapy. Expression of senescence markers p16 (INK4a) and ARF mRNA was determined using TaqMan quantitative reverse-transcription polymerase chain reaction in CD3(+) T lymphocytes, telomere length was determined by Southern analysis, and senescence-associated cytokines were determined by enzyme-linked immunosorbent assay. Findings were independently assessed in a cross-sectional cohort of 176 breast cancer survivors enrolled a median of 3.4 years after treatment; 39% previously received chemotherapy. All statistical tests were two-sided.

RESULTS

In prospectively analyzed patients, expression of p16 (INK4a) and ARF increased immediately after chemotherapy and remained elevated 12 months after treatment. Median increase in log2 p16 (INK4a) was 0.81 (interquartile range = 0.28-1.62; Wilcoxon signed-rank P < .001), or a 75% absolute increase in expression, equivalent to the increase observed over 14.7 years of chronological aging. ARF expression was comparably increased (P < .001). Increased expression of p16 (INK4a) and ARF was associated with dose-dense therapy and hematological toxicity. Expression of two senescence-associated cytokines (VEGFA and MCP1) was durably increased by adjuvant chemotherapy. Telomere length was not affected by chemotherapy. In a cross-sectional cohort, prior chemotherapy exposure was independently associated with a log2-increase in p16 (INK4a) expression of 0.57 (repeated measures model, P < .001), comparable with 10.4 years of chronological aging.

CONCLUSIONS

Adjuvant chemotherapy for breast cancer is gerontogenic, inducing cellular senescence in vivo, thereby accelerating molecular aging of hematopoietic tissues.

Phase II Trial of Cetuximab and Conformal Radiotherapy Only in Locally Advanced Pancreatic Cancer with Concurrent Tissue Sampling Feasibility Study

BACKGROUND

Preclinical data have indicated the anti-epidermal growth factor receptor (EGFR) agent cetuximab (Erbitux) as a radiosensitizer in pancreatic cancer, but this has not been specifically addressed in a clinical study. We report the results of an original study initiated in 2007, where cetuximab was tested with radiotherapy (RT) alone in locally advanced pancreatic cancer in a phase II trial (PACER).

METHODS

Patients (n = 21) received cetuximab loading dose (400 mg/m(2)) and weekly dose (250 mg/m(2)) during RT (50.4 Gy in 28 fractions). Toxicity and disease response end point data were prospectively assessed. A feasibility study of on-trial patient blood and skin sampling was incorporated.

RESULTS

Treatment was well tolerated, and toxicity was low; most patients (71%) experienced acute toxicities of grade 2 or less. Six months posttreatment, stable local disease was achieved in 90% of evaluable patients, but only 33% were free from metastatic progression. Median overall survival was 7.5 months, and actuarial survival was 33% at 1 year and 11% at 3 years, reflecting swift metastatic progression in some patients but good long-term control of localized disease in others. High-grade acneiform rash (P = .0027), posttreatment stable disease (P = .0059), and pretreatment cancer antigen 19.9 (CA19.9) level (P = .0042) associated with extended survival. Patient skin and blood samples yielded sufficient RNA and good quality protein, respectively.

CONCLUSIONS

The results indicate that cetuximab inhibits EGFR-mediated radioresistance to achieve excellent local control with minimal toxicity but does not sufficiently control metastatic progression in all patients. Translational studies of patient tissue samples may yield molecular information that may enable individual treatment response prediction.

Hypofractionated image-guided IMRT in advanced pancreatic cancer with simultaneous integrated boost to infiltrated vessels concomitant with capecitabine: a phase I study

PURPOSE

To determine the maximum tolerated radiation dose (MTD) of an integrated boost to the tumor subvolume infiltrating vessels, delivered simultaneously with radical dose to the whole tumor and concomitant capecitabine in patients with pretreated advanced pancreatic adenocarcinoma.

METHODS AND MATERIALS

Patients with stage III or IV pancreatic adenocarcinoma without progressive disease after induction chemotherapy were eligible. Patients underwent simulated contrast-enhanced four-dimensional computed tomography and fluorodeoxyglucose-labeled positron emission tomography. Gross tumor volume 1 (GTV1), the tumor, and GTV2, the tumor subvolume 1 cm around the infiltrated vessels, were contoured. GTVs were fused to generate Internal Target Volume (ITV)1 and ITV2. Biological tumor volume (BTV) was fused with ITV1 to create the BTV+Internal Target Volume (ITV) 1. A margin of 5/5/7 mm (7 mm in cranium-caudal) was added to BTV+ITV1 and to ITV2 to create Planning Target Volume (PTV) 1 and PTV2, respectively. Radiation therapy was delivered with tomotherapy. PTV1 received a fixed dose of 44.25 Gy in 15 fractions, and PTV2 received a dose escalation from 48 to 58 Gy as simultaneous integrated boost (SIB) in consecutive groups of at least 3 patients. Concomitant chemotherapy was capecitabine, 1250 mg/m(2) daily. Dose-limiting toxicity (DLT) was defined as any treatment-related G3 nonhematological or G4 hematological toxicity occurring during the treatment or within 90 days from its completion.

RESULTS

From June 2005 to February 2010, 25 patients were enrolled. The dose escalation on the SIB was stopped at 58 Gy without reaching the MTD. One patient in the 2(nd) dose level (50 Gy) had a DLT: G3 acute gastric ulcer. Three patients had G3 late adverse effects associated with gastric and/or duodenal mucosal damage. All patients received the planned dose of radiation.

CONCLUSIONS

A dose of 44.25 Gy in 15 fractions to the whole tumor with an SIB of 58 Gy to small tumor subvolumes concomitant with capecitabine is feasible in chemotherapy-pretreated patients with advanced pancreatic cancer.

Adequacy of inhale/exhale breathhold CT based ITV margins and image-guided registration for free-breathing pancreas and liver SBRT

Purpose

To evaluate use of breath-hold CTs and implanted fiducials for definition of the internal target volume (ITV) margin for upper abdominal stereotactic body radiation therapy (SBRT). To study the statistics of inter- and intra-fractional motion information.

Methods and materials

11 patients treated with SBRT for locally advanced pancreatic cancer (LAPC) or liver cancer were included in the study. Patients underwent fiducial implantation, free-breathing CT and breath-hold CTs at end inhalation/exhalation. All patients were planned and treated with SBRT using volumetric modulated arc therapy (VMAT). Two margin strategies were studied: Strategy I uses PTV = ITV + 3 mm; Strategy II uses PTV = GTV + 1.5 cm. Both CBCT and kV orthogonal images were taken and analyzed for setup before patient treatments. Tumor motion statistics based on skeletal registration and on fiducial registration were analyzed by fitting to Gaussian functions.

Results

All 11 patients met SBRT planning dose constraints using strategy I. Average ITV margins for the 11 patients were 2 mm RL, 6 mm AP, and 6 mm SI. Skeletal registration resulted in high probability (RL = 69%, AP = 4.6%, SI = 39%) that part of the tumor will be outside the ITV. With the 3 mm ITV expansion (Strategy 1), the probability reduced to RL 32%, AP 0.3%, SI 20% for skeletal registration; and RL 1.2%, AP 0%, SI 7% for fiducial registration. All 7 pancreatic patients and 2 liver patients failed to meet SBRT dose constraints using strategy II. The liver dose was increased by 36% for the other 2 liver patients that met the SBRT dose constraints with strategy II.

Conclusions

Image guidance matching to skeletal anatomy is inadequate for SBRT positioning in the upper abdomen and usage of fiducials is highly recommended. Even with fiducial implantation and definition of an ITV, a minimal 3 mm planning margin around the ITV is needed to accommodate intra-fractional uncertainties.

Accelerated fraction radiotherapy with capecitabine as neoadjuvant therapy for borderline resectable pancreatic cancer

BACKGROUND

A standard neoadjuvant regimen has not been defined for borderline resectable (BR) pancreatic cancer. This phase II trial was designed to determine the safety of accelerated fraction radiotherapy (AFRT) with capecitabine in patients with BR pancreatic cancer.

METHODS

The patients had newly diagnosed BR adenocarcinoma of the pancreas and normal organ function. Intensity-modulated (n = 11) or 3D conformal (n = 2) radiotherapy was given to a dose of 50 Gy in 2.5-Gy fractions with capecitabine 825 mg/m(2) twice on radiation days. The primary outcome was the frequency of severe treatment-related adverse events (AEs). The study was stopped before planned interim analysis because of 2 severe (grades 4 and 5) gastric ulcerations.

RESULTS

Thirteen patients were enrolled with a median age of 66 years. All patients completed treatment. Seven (54%) experienced grade 3+ treatment-related AEs. Severe gastric ulceration occurred in 2 patients despite receipt of ≥43 Gy to only 1% (2-3 cm(3)) of the stomach. Lymphopenia (n = 7) was the only other severe AE that occurred in >1 patient. In 7 of the 13 patients, disease had progressed outside the pancreas at restaging. Five of the 13 underwent resection, and all had >10% viable tumor. Median progression-free survival (PFS) was 2.4 months (95% CI 1.9-5.9), and median survival was 9.1 months (95% CI 5.9-not reached). Among those who underwent resection, median PFS was 13.0 months (95% CI 4.4-not reached). Median survival was not reached.

CONCLUSIONS

Given the limited efficacy signal and severe gastric ulcerations, we do not recommend this regimen for pancreatic cancer. We also do not recommend the use of high doses per fraction outside a clinical trial.

Interfractional dose variations in the stomach and the bowels during breathhold intensity-modulated radiotherapy for pancreatic cancer: Implications for a dose-escalation strategy

PURPOSE

This study aims to evaluate the interfractional dose variations in the organs-at-risk (OARs) during pancreatic breathhold intensity-modulated radiotherapy (IMRT) and to assess the impacts of "planning organs-at-risk volume" (POV) structures generated by isotropically expanding the dose-limiting OARs, based on the comparison of the interfractional doses to the OARs between IMRT plans and conventional three-dimensional-conformal radiotherapy (3D-CRT) plans.

METHODS

Thirty repeat CT scans were acquired from ten consecutive patients who were receiving chemoradiotherapy for pancreatic cancer. Six IMRT plans for each patient with two levels of prescription (45 and 51 Gy in 15 fractions) and 3 POV margin sizes (5, 7, and 10 mm) were generated based on the initial CT scan under predetermined constraints. Two 3D-CRT plans (39 and 42 Gy in 15 fractions) were simultaneously generated. The dose distribution of all of the treatment plans was recalculated with the repeat CT scans. The interfractional dose variations in the three OARs (stomach, duodenum, and small intestine) were evaluated, and the absolute volumes ≥39 Gy (V39Gy) of the OARs in the IMRT plans were compared to those in the 3D-CRT plans. Regression analyses were performed to assess the relative impact of the factors of interest on the interfractional dose variations of the OARs.

RESULTS

Substantial dose excesses to the three OARs were observed at all of the prescription dose levels and the POV margin sizes on the repeat CT scans. The safety threshold based on the mean stomach V39Gy on the recalculated 39 Gy-3D-CRT plans was 1.9 ml. Statistically significant and marginally insignificant mean V39Gy values above the safety thresholds were observed in the stomach in the 51 Gy-IMRT plans (2.6 and 2.1 ml with the 5- and 7-mm PRV margins, respectively (P = 0.015 and 0.085)). Only in the case of the 10-mm POV margin did the metric fall below the safety threshold to 1.5 ml (P = 0.634). The duodenum and the small intestine did not violate the safety thresholds (1.4 and 3.8 ml, respectively). From the multiple regression analyses, only the margin size (P < 0.001) and the POV V39Gy (P < 0.001) were significantly associated with the distribution of recalculated V39Gy for the stomach. Multiple factors, including the margin size (P = 0.020) and the POV V39Gy (P < 0.001) were associated with the recalculated V39Gy for the duodenum. However, none of the POV parameters for the small intestine were associated with the recalculated V39Gy.

CONCLUSIONS

Considerable interfractional dose variation was observed in three critical OARs. At the escalated prescription dose of breathhold IMRT, the dose variations could exceed the dose variations using 3D-CRT at the safe prescription dose level, indicating that a dose-escalation strategy based solely on the initial advantageous dose distribution in a breathhold IMRT can be problematic. Given the current limitations for predicting or coping with variation throughout the treatment course, the use of POV should be considered for safely delivering escalated doses to 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.

Phase 2 study of erlotinib combined with adjuvant chemoradiation and chemotherapy in patients with resectable pancreatic cancer

PURPOSE

Long-term survival rates for patients with resected pancreatic ductal adenocarcinoma (PDAC) have stagnated at 20% for more than a decade, demonstrating the need to develop novel adjuvant therapies. Gemcitabine-erlotinib therapy has demonstrated a survival benefit for patients with metastatic PDAC. Here we report the first phase 2 study of erlotinib in combination with adjuvant chemoradiation and chemotherapy for resected PDAC.

METHODS AND MATERIALS

Forty-eight patients with resected PDAC received adjuvant erlotinib (100 mg daily) and capecitabine (800 mg/m(2) twice daily Monday-Friday) concurrently with intensity modulated radiation therapy (IMRT), 50.4 Gy over 28 fractions followed by 4 cycles of gemcitabine (1000 mg/m(2) on days 1, 8, and 15 every 28 days) and erlotinib (100 mg daily). The primary endpoint was recurrence-free survival (RFS).

RESULTS

The median follow-up time was 18.2 months (interquartile range, 13.8-27.1). Lymph nodes were positive in 85% of patients, and margins were positive in 17%. The median RFS was 15.6 months (95% confidence interval [CI], 13.4-17.9), and the median overall survival (OS) was 24.4 months (95% CI, 18.9-29.7). Multivariate analysis with adjustment for known prognostic factors showed that tumor diameter >3 cm was predictive for inferior RFS (hazard ratio, 4.01; P=.001) and OS (HR, 4.98; P=.02), and the development of dermatitis was associated with improved RFS (HR, 0.27; P=.009). During CRT and post-CRT chemotherapy, the rates of grade 3/4 toxicity were 31%/2% and 35%/8%, respectively.

CONCLUSION

Erlotinib can be safely administered with adjuvant IMRT-based CRT and chemotherapy. The efficacy of this regimen appears comparable to that of existing adjuvant regimens. Radiation Therapy Oncology Group 0848 will ultimately determine whether erlotinib produces a survival benefit in patients with resected pancreatic cancer.

Intensity modulated radiotherapy as neoadjuvant chemoradiation for the treatment of patients with locally advanced pancreatic cancer. Outcome analysis and comparison with a 3D-treated patient cohort

BACKGROUND

To evaluate outcome after intensity modulated radiotherapy (IMRT) compared to 3D conformal radiotherapy (3D-RT) as neoadjuvant treatment in patients with locally advanced pancreatic cancer (LAPC).

MATERIALS AND METHODS

In total, 57 patients with LAPC were treated with IMRT and chemotherapy. A median total dose of 45 Gy to the PTV_baseplan and 54 Gy to the PTV_boost in single doses of 1.8 Gy for the PTV_baseplan and median single doses of 2.2 Gy in the PTV_boost were applied. Outcomes were evaluated and compared to a large cohort of patients treated with 3D-RT.

RESULTS

Overall treatment was well tolerated in all patients and IMRT could be completed without interruptions. Median overall survival was 11 months (range 5-37.5 months). Actuarial overall survival at 12 and 24 months was 36 % and 8 %, respectively. A significant impact on overall survival could only be observed for a decrease in CA 19-9 during treatment, patients with less pre-treatment CA 19-9 than the median, as well as weight loss during treatment. Local progression-free survival was 79 % after 6 months, 39 % after 12 months, and 13 % after 24 months. No factors significantly influencing local progression-free survival could be identified. There was no difference in overall and progression-free survival between 3D-RT and IMRT. Secondary resectability was similar in both groups (26 % vs. 28 %). Toxicity was comparable and consisted mainly of hematological toxicity due to chemotherapy.

CONCLUSION

IMRT leads to a comparable outcome compared to 3D-RT in patients with LAPC. In the future, the improved dose distribution, as well as advances in image-guided radiotherapy (IGRT) techniques, may improve the use of IMRT in local dose escalation strategies to potentially improve outcome.

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.

Dosimetric and clinical predictors of toxicity following combined chemotherapy and moderately hypofractionated rotational radiotherapy of locally advanced pancreatic adenocarcinoma

BACKGROUND AND PURPOSE

Hypofractionated radiotherapy (RT) of pancreatic adenocarcinoma is limited by the tolerance of adjacent normal tissues. A better understanding of the influence of dosimetric variables on the rate of toxicity after RT must be considered an important goal.

METHODS AND MATERIALS

Sixty-one patients with histologically proven locally advanced disease (LAPD) were analyzed. The therapeutic strategy consisted of induction chemotherapy (ChT) followed by concurrent chemoradiotherapy (CRT). In 39 out of 61 patients the target volume was based on a four-dimensional CT (4D-CT) procedure. Delivered dose was 44.25Gy in 15 fractions to PTV2, which consisted of pancreatic tumor and regional lymph nodes considered radiologically involved; 23 out of 61 patients received a simultaneous integrated boost (SIB) to a tumor sub-volume infiltrating the great abdominal vessels (PTV1) with dose in the range of 48-58Gy. RT was delivered with Helical Tomotherapy. Dose-volume histograms (DVHs) of target volumes and organs at risk (OARs) were collected for analysis. The predictive value of clinical/dosimetric parameters was tested by univariate/multivariate analyses.

RESULTS

The crude incidence of acute gastrointestinal (GI) grade 2 toxicity was 33%. The 12-month actuarial rate of "anatomical" (gastro-duodenal mucosa damage) toxicity was 13% (95% CI: 4-22%). On univariate analysis, several stomach and duodenum DVH endpoints are predictive of toxicity after moderately hypofractionated radiotherapy. Multivariate analysis confirmed that baseline performance status and the stomach V20[%] were strong independent predictors of acute GI grade ⩾2 toxicity. The high-dose region of duodenum DVH (V45[%]; V40[%]) was strongly correlated with grade ⩾2 "anatomical" toxicity; the best V40[%] and V45[%] cut-off values were 16% and 2.6% respectively.

CONCLUSION

Regarding dosimetric indices, stomach V20[%] correlates with a higher rate of acute toxicity; more severe acute and late anatomical toxicities are related to the high dose region of duodenum DVH.

Sensitization of pancreatic cancer to chemoradiation by the Chk1 inhibitor MK8776

PURPOSE

The combination of radiation with chemotherapy is the most effective therapy for unresectable pancreatic cancer. To improve upon this regimen, we combined the selective Checkpoint kinase 1 (Chk1) inhibitor MK8776 with gemcitabine-based chemoradiation in preclinical pancreatic cancer models.

EXPERIMENTAL DESIGN

We tested the ability of MK8776 to sensitize to gemcitabine-radiation in homologous recombination repair (HRR)-proficient and -deficient pancreatic cancer cells and assessed Rad51 focus formation. In vivo, we investigated the efficacy, tumor cell selectivity, and pharmacodynamic biomarkers of sensitization by MK8776.

RESULTS

We found that MK8776 significantly sensitized HRR-proficient (AsPC-1, MiaPaCa-2, BxPC-3) but not -deficient (Capan-1) pancreatic cancer cells to gemcitabine-radiation and inhibited Rad51 focus formation in HRR-proficient cells. In vivo, MiaPaCa-2 xenografts were significantly sensitized to gemcitabine-radiation by MK8776 without significant weight loss or observable toxicity in the small intestine, the dose-limiting organ for chemoradiation therapy in pancreatic cancer. We also assessed pChk1 (S345), a pharmacodynamic biomarker of DNA damage in response to Chk1 inhibition in both tumor and small intestine and found that MK8776 combined with gemcitabine or gemcitabine-radiation produced a significantly greater increase in pChk1 (S345) in tumor relative to small intestine, suggesting greater DNA damage in tumor than in normal tissue. Furthermore, we demonstrated the utility of an ex vivo platform for assessment of pharmacodynamic biomarkers of Chk1 inhibition in pancreatic cancer.

CONCLUSIONS

Together, our results suggest that MK8776 selectively sensitizes HRR-proficient pancreatic cancer cells and xenografts to gemcitabine-radiation and support the clinical investigation of MK8776 in combination with gemcitabine-radiation in locally advanced pancreatic cancer.

Inhibition of protein phosphatase 2A radiosensitizes pancreatic cancers by modulating CDC25C/CDK1 and homologous recombination repair

PURPOSE

To identify targets whose inhibition may enhance the efficacy of chemoradiation in pancreatic cancer and thus improve survival, we conducted an siRNA library screen in pancreatic cancer cells. We investigated PPP2R1A, a scaffolding subunit of protein phosphatase 2A (PP2A) as a lead radiosensitizing target.

EXPERIMENTAL DESIGN

We determined the effect of PP2A inhibition by genetic (PPP2R1A siRNA) and pharmacologic (LB100, a small molecule entering phase I clinical trials) approaches on radiosensitization of Panc-1 and MiaPaCa-2 pancreatic cancer cells both in vitro and in vivo.

RESULTS

PPP2R1A depletion by siRNA radiosensitized Panc-1 and MiaPaCa-2 cells, with radiation enhancement ratios of 1.4 (P < 0.05). Likewise, LB100 produced similar radiosensitization in pancreatic cancer cells, but minimal radiosensitization in normal small intestinal cells. Mechanistically, PPP2R1A siRNA or LB100 caused aberrant CDK1 activation, likely resulting from accumulation of the active forms of PLK1 (pPLK1 T210) and CDC25C (pCDC25C T130). Furthermore, LB100 inhibited radiation-induced Rad51 focus formation and homologous recombination repair (HRR), ultimately leading to persistent radiation-induced DNA damage, as reflected by γ-H2AX expression. Finally, we identified CDC25C as a key PP2A substrate involved in LB100-mediated radiosensitization as depletion of CDC25C partially reversed LB100-mediated radiosensitization. In a mouse xenograft model of human pancreatic cancer, LB100 produced significant radiosensitization with minimal weight loss.

CONCLUSIONS

Collectively, our data show that PP2A inhibition radiosensitizes pancreatic cancer both in vitro and in vivo via activation of CDC25C/CDK1 and inhibition of HRR, and provide proof-of-concept evidence that PP2A is a promising target for the improvement of local therapy in pancreatic cancer.

A multi-institutional phase 2 study of neoadjuvant gemcitabine and oxaliplatin with radiation therapy in patients with pancreatic cancer

BACKGROUND

The purpose of this study was to evaluate preoperative treatment with full-dose gemcitabine, oxaliplatin, and radiation therapy (RT) in patients with localized pancreatic cancer.

METHODS

Eligibility included confirmation of adenocarcinoma, resectable or borderline resectable disease, a performance status ≤2, and adequate organ function. Treatment consisted of two 28-day cycles of gemcitabine (1 g/m(2) over 30 minutes on days 1, 8, and 15) and oxaliplatin (85 mg/m(2) on days 1 and 15) with RT during cycle 1 (30 Gray [Gy] in 2-Gy fractions). Patients were evaluated for surgery after cycle 2. Patients who underwent resection received 2 cycles of adjuvant chemotherapy.

RESULTS

Sixty-eight evaluable patients received treatment at 4 centers. By central radiology review, 23 patients had resectable disease, 39 patients had borderline resectable disease, and 6 patients had unresectable disease. Sixty-six patients (97%) completed cycle 1 with RT, and 61 patients (90%) completed cycle 2. Grade ≥3 adverse events during preoperative therapy included neutropenia (32%), thrombocytopenia (25%), and biliary obstruction/cholangitis (14%). Forty-three patients underwent resection (63%), and complete (R0) resection was achieved in 36 of those 43 patients (84%). The median overall survival was 18.2 months (95% confidence interval, 13-26.9 months) for all patients, 27.1 months (95% confidence interval, 21.2-47.1 months) for those who underwent resection, and 10.9 months (95% confidence interval, 6.1-12.6 months) for those who did not undergo resection. A decrease in CA 19-9 level after neoadjuvant therapy was associated with R0 resection (P = .02), which resulted in a median survival of 34.6 months (95% confidence interval, 20.3-47.1 months). Fourteen patients (21%) are alive and disease free at a median follow-up of 31.4 months (range, 24-47.6 months).

CONCLUSIONS

Preoperative therapy with full-dose gemcitabine, oxaliplatin, and RT was feasible and resulted in a high percentage of R0 resections. The current results are particularly encouraging, because the majority of patients had borderline resectable disease.

Proton therapy with concomitant capecitabine for pancreatic and ampullary cancers is associated with a low incidence of gastrointestinal toxicity

BACKGROUND

To review treatment toxicity for patients with pancreatic and ampullary cancer treated with proton therapy at our institution.

MATERIAL AND METHODS

From March 2009 through April 2012, 22 patients were treated with proton therapy and concomitant capecitabine (1000 mg PO twice daily) for resected (n = 5); marginally resectable (n = 5); and unresectable/inoperable (n = 12) biopsy-proven pancreatic and ampullary adenocarcinoma. Two patients with unresectable disease were excluded from the analysis for reasons unrelated to treatment. Proton doses ranged from 50.40 cobalt gray equivalent (CGE) to 59.40 CGE.

RESULTS

Median follow-up for all patients was 11 (range 5-36) months. No patient demonstrated any grade 3 toxicity during treatment or during the follow-up period. Grade 2 gastrointestinal toxicities occurred in three patients, consisting of vomiting (n = 3); and diarrhea (n = 2). Median weight loss during treatment was 1.3 kg (1.75% of body weight). Chemotherapy was well-tolerated with a median 99% of the prescribed doses delivered. Percentage weight loss was reduced (p = 0.0390) and grade 2 gastrointestinal toxicity was eliminated (p = 0.0009) in patients treated with plans that avoided anterior and left lateral fields which were associated with reduced small bowel and gastric exposure.

DISCUSSION

Proton therapy may allow for significant sparing of the small bowel and stomach and is associated with a low rate of gastrointestinal toxicity. Although long-term follow-up will be needed to assess efficacy, we believe that the favorable toxicity profile associated with proton therapy may allow for radiotherapy dose escalation, chemotherapy intensification, and possibly increased acceptance of preoperative radiotherapy for patients with resectable or marginally resectable disease.

Gemcitabine-based or capecitabine-based chemoradiotherapy for locally advanced pancreatic cancer (SCALOP): a multicentre, randomised, phase 2 trial

BACKGROUND

In the UK, chemotherapy is the standard treatment for inoperable, locally advanced, non-metastatic pancreatic cancer. Chemoradiotherapy is also an acceptable treatment option, for which gemcitabine, fluorouracil, or capecitabine can be used as concurrent chemotherapy agents. We aimed to assess the activity, safety, and feasibility of both gemcitabine-based and capecitabine-based chemoradiotherapy after induction chemotherapy for patients with locally advanced pancreatic cancer.

METHODS

In this open-label, randomised, two-arm, phase 2 trial, patients aged 18 years or older with histologically proven, locally advanced pancreatic cancer (with a tumour diameter of 7 cm or less) were recruited from 28 UK centres between Dec 24, 2009 and Oct 25, 2011. After 12 weeks of induction gemcitabine and capecitabine chemotherapy (three cycles of gemcitabine [1000 mg/m(2) on days 1, 8, 15 of a 28-day cycle] and capecitabine [830 mg/m(2) twice daily on days 1-21 of a 28-day cycle]), patients with stable or responding disease, tumour diameter of 6 cm or less, and WHO performance status 0-1 were randomly assigned to receive a further cycle of gemcitabine and capecitabine chemotherapy followed by either gemcitabine (300 mg/m(2) once per week) or capecitabine (830 mg/m(2) twice daily, Monday to Friday only), both in combination with radiation (50·4 Gy in 28 fractions). Randomisation (1:1) was done via a central computerised system and used stratified minimisation. The primary endpoint was 9-month progression-free survival, analysed by intention to treat including only those patients with valid CT assessments. This trial is registered with ISRCTN, number 96169987.

FINDINGS

114 patients were registered and 74 were randomly allocated (38 to the gemcitabine group and 36 to the capecitabine group). After 9 months, 22 of 35 assessable patients (62·9%, 80% CI 50·6-73·9) in the capecitabine group and 18 of 35 assessable patients (51·4%, 39·4-63·4) in the gemcitabine group had not progressed. Median overall survival was 15·2 months (95% CI 13·9-19·2) in the capecitabine group and 13·4 months (95% CI 11·0-15·7) in the gemcitabine group (adjusted hazard ratio [HR] 0·39, 95% CI 0·18-0·81; p=0·012). 12-month overall survival was 79·2% (95% CI 61·1-89·5) in the capecitabine group and 64·2 (95% CI 46·4-77·5) in the gemcitabine group. Median progression-free survival was 12·0 months (95% CI 10·2-14·6) in the capecitabine group and 10·4 months (95% CI 8·9-12·5) in the gemcitabine group (adjusted HR 0·60, 95% CI 0·32-1·12; p=0·11). Eight patients in the capecitabine group had an objective response at 26 weeks, as did seven in the gemcitabine group. More patients in the gemcitabine group than in the capecitabine group had grade 3-4 haematological toxic effects (seven [18%] vs none, p=0·008) and non-haematological toxic effects (ten [26%] vs four [12%], p=0·12) during chemoradiation treatment; the most frequent events were leucopenia, neutropenia, and fatigue. Two patients in the capecitabine group progressed during the fourth cycle of induction chemotherapy. Of the 34 patients in the capecitabine group who received chemoradiotherapy, 25 (74%) received the full protocol dose of radiotherapy, compared with 26 (68%) of 38 patients in the gemcitabine group. Quality-of-life scores were not significantly different between the treatment groups.

INTERPRETATION

Our results suggest that a capecitabine-based regimen might be preferable to a gemcitabine-based regimen in the context of consolidation chemoradiotherapy after a course of induction chemotherapy for locally advanced pancreatic cancer. However, these findings should be interpreted with caution because the difference in the primary endpoint was non-significant and the number of patients in the trial was small.

FUNDING

Cancer Research UK.

Prognostic significance of carbohydrate antigen 19-9 in unresectable locally advanced pancreatic cancer treated with dose-escalated intensity modulated radiation therapy and concurrent full-dose gemcitabine: analysis of a prospective phase 1/2 dose escalation study

PURPOSE

Although established in the postresection setting, the prognostic value of carbohydrate antigen 19-9 (CA19-9) in unresectable locally advanced pancreatic cancer (LAPC) is less clear. We examined the prognostic utility of CA19-9 in patients with unresectable LAPC treated on a prospective trial of intensity modulated radiation therapy (IMRT) dose escalation with concurrent gemcitabine.

METHODS AND MATERIALS

Forty-six patients with unresectable LAPC were treated at the University of Michigan on a phase 1/2 trial of IMRT dose escalation with concurrent gemcitabine. CA19-9 was obtained at baseline and during routine follow-up. Cox models were used to assess the effect of baseline factors on freedom from local progression (FFLP), distant progression (FFDP), progression-free survival (PFS), and overall survival (OS). Stepwise forward regression was used to build multivariate predictive models for each endpoint.

RESULTS

Thirty-eight patients were eligible for the present analysis. On univariate analysis, baseline CA19-9 and age predicted OS, CA19-9 at baseline and 3 months predicted PFS, gross tumor volume (GTV) and black race predicted FFLP, and CA19-9 at 3 months predicted FFDP. On stepwise multivariate regression modeling, baseline CA19-9, age, and female sex predicted OS; baseline CA19-9 and female sex predicted both PFS and FFDP; and GTV predicted FFLP. Patients with baseline CA19-9 ≤ 90 U/mL had improved OS (median 23.0 vs 11.1 months, HR 2.88, P<.01) and PFS (14.4 vs 7.0 months, HR 3.61, P=.001). CA19-9 progression over 90 U/mL was prognostic for both OS (HR 3.65, P=.001) and PFS (HR 3.04, P=.001), and it was a stronger predictor of death than either local progression (HR 1.46, P=.42) or distant progression (HR 3.31, P=.004).

CONCLUSIONS

In patients with unresectable LAPC undergoing definitive chemoradiation therapy, baseline CA19-9 was independently prognostic even after established prognostic factors were controlled for, whereas CA19-9 progression strongly predicted disease progression and death. Future trials should stratify by baseline CA19-9 and incorporate CA19-9 progression as a criterion for progressive disease.

Dose-painted intensity modulated radiation therapy improves local control for locally advanced pancreas cancer

Background. To evaluate the outcomes, adverse events, and therapeutic role of Dose-Painted Intensity-Modulated Radiation Therapy (DP-IMRT) for locally advanced pancreas cancer (LAPC). Methods. Patients with LAPC were treated with induction chemotherapy (n = 25) and those without metastasis (n = 20) received DP-IMRT consisting of 45 Gy to Planning Treatment Volume 1 (PTV1) including regional lymph nodes with a concomitant boost to the PTV2 (gross tumor volume + 0.5 cm) to either 50.4 Gy (n = 9) or 54 Gy (n = 11) in 25 fractions. DP-IMRT cases were compared to three-dimensional conformal radiation therapy (3D-CRT) plans to assess the potential relationship of radiation dose to adverse events. Kaplan-Meier and Cox regression analyses were used to calculate survival probabilities. The Fisher exact test and t-test were utilized to investigate potential prognostic factors of toxicity and survival. Results. Median overall and progression-free survivals were 11.6 and 5.9 months, respectively. Local control was 90%. Post-RT CA-19-9 levels following RT were predictive of survival (P = 0.02). Grade 2 and ≥grade 3 GI toxicity were 60% and 20%, respectively. In comparison to 3D-CRT, DP-IMRT plans demonstrated significantly lower V45 values of small bowel (P = 0.0002), stomach (P = 0.007), and mean liver doses (P = 0.001). Conclusions. Dose-escalated DP-IMRT offers improved local control in patients treated with induction chemotherapy for LAPC. Radiation-related morbidity appears reduced with DP-IMRT compared to 3D-CRT techniques, likely due to reduction in RT doses to organs at risk.

Radiation dose ≥54 Gy and CA 19-9 response are associated with improved survival for unresectable, non-metastatic pancreatic cancer treated with chemoradiation

BACKGROUND

Unresectable pancreatic cancer (UPC) has low survival. With improving staging techniques and systemic therapy, local control in patients without metastatic disease may have increasing importance. We investigated whether the radiation dose used in chemoradiation (CRT) as definitive treatment for UPC and the CA 19-9 response to therapy have an impact on overall survival (OS).

METHODS

From 1997-2009 46 patients were treated with CRT for non-metastatic UPC. Median prescribed RT dose was 54 Gy (range 50.4-59.4 Gy). All patients received concurrent chemotherapy (41: 5-fluorouracil, 5: other) and 24 received adjuvant chemotherapy.

RESULTS

41 patients were inoperable due to T4 disease and 5 patients with T3 disease were medically inoperable. Five patients did not complete CRT due to progressive disease or treatment-related toxicity (median RT dose 43.2 Gy). Overall, 42 patients were dead of disease at the time of last follow-up. The median and 12 month OS were 8.8 months and 35%, respectively. By univariate analysis, minimum CA 19-9 post-CRT <90 U/mL was favorably associated with OS (12.3 versus 8.8 months, p = 0.012). Radiotherapy dose ≥54 Gy trended towards improved OS (11.3 versus 6.8 months, p = 0.089). By multivariable analysis, a delivered RT dose of ≥54 Gy (HR 0.47, p = 0.028) and minimum CA 19-9 post-CRT of <90 U/mL (HR 0.35, p = 0.008) were associated with OS.

CONCLUSIONS

CRT as definitive treatment for UPC had low survival. However, our retrospective data suggest that patients treated to ≥54 Gy or observed to have a minimum post-CRT CA 19-9 <90 U/mL had improved likelihood of long-term survival.

Selective radiosensitization of p53 mutant pancreatic cancer cells by combined inhibition of Chk1 and PARP1

We have recently shown that inhibition of HRR (homologous recombination repair) by Chk1 (checkpoint kinase 1) inhibition radiosensitizes pancreatic cancer cells and others have demonstrated that Chk1 inhibition selectively sensitizes p53 mutant tumor cells. Furthermore, PARP1 [poly (ADP-ribose) polymerase-1] inhibitors dramatically radiosensitize cells with DNA double strand break repair defects. Thus, we hypothesized that inhibition of HRR (mediated by Chk1 via AZD7762) and PARP1 [via olaparib (AZD2281)] would selectively sensitize p53 mutant pancreatic cancer cells to radiation. We also used 2 isogenic p53 cell models to assess the role of p53 status in cancer cells and intestinal epithelial cells to assess overall cancer specificity. DNA damage response and repair were assessed by flow cytometry, γH2AX, and an HRR reporter assay. We found that the combination of AZD7762 and olaparib produced significant radiosensitization in p53 mutant pancreatic cancer cells and in all of the isogenic cancer cell lines. The magnitude of radiosensitization by AZD7762 and olaparib was greater in p53 mutant cells compared with p53 wild type cells. Importantly, normal intestinal epithelial cells were not radiosensitized. The combination of AZD7762 and olaparib caused G 2 checkpoint abrogation, inhibition of HRR, and persistent DNA damage responses. These findings demonstrate that the combination of Chk1 and PARP1 inhibition selectively radiosensitizes p53 mutant pancreatic cancer cells. Furthermore, these studies suggest that inhibition of HRR by Chk1 inhibitors may be a useful strategy for selectively inducing a BRCA1/2 'deficient-like' phenotype in p53 mutant tumor cells, while sparing normal tissue.