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ESTRO 36 2017
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(PDAC). Microscopically incomplete resection (R1) is often
associated with early local recurrence (LR) and, therefore,
represents a negative prognostic factor. The aim of this
study was to analyze the total PDAC proteome of patients
who received radiochemotherapy (RCT) following
incomplete resection in order to identify proteins
associated with post-RCT LR.
Material and Methods
Thee patients with early LR (median 6 months after
resection, range 5 to 10 months) and three patients with
late LR (median 18 months after resection, range 13 to 27
months) were identified from our clinical database.
Formalin fixed paraffin-embedded tissue obtained from
surgical PDAC specimens was used for proteome analysis.
After micro-dissection, tissue was de-paraffinized and
rehydrated, followed by protein extraction and trypsin
digestion. The samples were analyzed by tandem mass
spectrometry. To identify significantly up- or down-
regulated proteins, linear models for microarray data
(LIMMA) were applied; the p-value was set to 0.01.
Results
Patients received a median RT total dose of 50.4Gy and
concurrent chemotherapy with two courses of 5-FU.
Overall survival was reduced in patients with early LR as
compared to patients with late LR (7 vs. 30 months,
p=0.0001). A total of 1,878 proteins were quantified in
both cohorts with 1,656 proteins quantified in the early LR
group and 1,769 quantified in the late LR group. LIMMA
method identified 18 proteins significantly up- or down-
regulated. 7 proteins were up-regulated in the early LR
group such as MAOA, ALDH1A1, creatine kinase B and
mucin-5AC being involved in tumorigenesis. 11 proteins
were up-regulated in the late LR group including fascin,
integrin beta-4, histidine rich glycoprotein and CDC42.
Further analysis demonstrated the early LR group to
exhibit an exocrine-like phenotype including expression of
pancreatic proteins absent in the late LR group. 13
exocrine-related proteins were identified such as
carboxypeptidase B and chymotrypsin-C.
Conclusion
Analyzing proteomic data of PDAC patients undergoing
post-operative RCT after R1-resection, proteomic
expression profiles associated with early vs. late post-RCT
LR were identified. These proteomic biomarkers may
serve to stratify patients according to prognosis in future
trials and to assess a potential benefit of post-operative
RCT.
PO-0954 A model to study long-term impact of
radiation towards the colorectal area
F. Sjöberg
1
, D. Malipatlolla
1
, G. Steineck
1
, C. Bull
1
1
The Division of Clinical Cancer Epidemiology,
Department of Oncology- University of Gothenburg,
Gothenburg, Sweden
Purpose or Objective
A deeper understanding of the radiophysiology following
radiotherapy is imperative. With a few exceptions, rodent
models of high-dose gastrointestinal radiation injury
typically cause lethality within 5-8 days, limiting the
possibility to study the progression of injury over time. We
have developed a model that allows for delivering
radiation in fractions at high doses, while maintaining
excellent survival.
Material and Methods
Adult male C57/BL6 mice placed in a silicone mold were
exposed to rectal irradiation using a linear accelerator
(Varian Clinac 600 CD), the field limited to 1,5 cm of the
distal part of the colon. Each mouse received 6 or 8 Gy,
twice daily in 12 hours intervals, in 2, 3 or 4 fractions
total. Acute cell apoptosis was examined, and histological
changes at six weeks post-irradiation.
Results
Irradiation caused apoptosis at 4.5 hours, mainly limited
to the distal colon. At six weeks post-irradiation, crypts
displayed overt signs of radiation-induced degeneration,
as has been described in human irradiated intestinal
tissue. The number of degenerated crypts was heavily
increased at the fourth fraction, regardless of dose. The
number of macrophages, indicating inflammation, was
likewise apparent after the fourth fraction. Crypt damage
was restricted to individual crypts, nearby crypts were
unaffected with regards to cell production and survival.
Angiogenesis was induced, likely as a compensatory
mechanism for hypoxia.
Conclusion
Our model is suitable to study late gastrointestinal injury
induced by high-dose fractionated radiation. The
placement of the radiation field makes the model
especially convenient for testing interventions that can be
delivered rectally.
PO-0955 Co-treatment of MSC and vascular
permeability inhibitor reduces radiation side effects on
the colon
V. Monceau
1
, C. Demarquay
1
, A. Accarie
1
, L. Moussa
1
, B.
Doix
1
, M. Benderitter
1
, A. Sémont
1
, N. Mathieu
1
1
Institut de Radioprotection et de Sûreté Nucléaire IRSN,
PRP-HOM- SRBE- LR2I, Fontenay aux roses, France
Purpose or Objective
The efficacy of radiotherapy requires an optimal
compromise between tumor control and normal tissue
injury. Non-neoplastic tissues around abdomino-pelvic
tumor can be damaged by ionizing radiation leading to
acute and/or chronic gastrointestinal complications which
affect quality of life with substantial morbidity and
mortality. There is no unified approach to the assessment
and the treatment of radiotherapy delayed side effects,
characterized mainly by uncontrolled inflammation and
tissue fibrosis. We previously demonstrated that
mesenchymal stromal cells (MSC) treatment improves
colonic regeneration and reduces partially the ulcer size
by the margins (Sémont, 2013). Moreover, studies showed
that the vascular compartment is improved after MSC
treatment and could play a key role in the inflammatory
process and the epithelial regeneration. However, these
aspects have not yet been investigated after irradiation.
In this study, we investigate the effect of MSC treatment
on vascular compartment. We analyze the angiogenesis
process, progenitor’s recruitment in blood and associated
chemoattractant molecules secretion as well as vascular
permeability. The aim of this study is to determine a new
way to improve MSC treatment.
Material and Methods
We generated, in SD rat, colonic radiation-induced lesions
similar of those seen in patients suffering of late side
effects after pelvic radiotherapy (29Gy). Three weeks
after irradiation (established damages) 5.10
6
of MSC from
fat tissue were injected intravenously (IV).
Results
The first results showed that MSC treatment increase the
amount of blood vessels. This process is associated with
an increase of the growth factor VEGF, but also a
recruitment of endothelial progenitor cells, two events
necessary for the neo-vascularization. We also
demonstrated that MSC treatment ameliorates the quality
of blood vessels (the number of fully muscularized
capillaries was reduced in ulcer and border areas).
However, MSC treatment has no effect on the vascular
permeability nor the number of inflammatory cells.
Therefore, we realized MSC injections concomitantly with
an inhibitor of vascular permeability which was iteratively
infused intravenously. We demonstrated that the co-
treatment reduces considerably the size of the ulcer
comparatively with only MSC treatment suggesting that
the beneficial effects of MSC were potentiated with an
inhibitor of vascular permeability.
Conclusion