Free circulating tumour DNA in patients with peritoneal metastases of colorectal origin and HIPEC therapy; LIBEC trial - a feasibility study

Peritoneal carcinomatosis (PC) of colorectal origin occurs in 13 per cent of
the patients at time of diagnosis and 25% of the patients develop PC at
recurrence. Prognosis for PC without aggressive therapy is poor. Without
treatment, median survival is approximately 3 months. Cytoreductive surgery
(CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has been
reported to have significant benefit on survival of peritoneally metastasized
gastro-intestinal and gynaecological carcinomas. Median survival of patients
with PC of colorectal origin has improved with 21-30 months and 30 to 50%
5-year survival7.

Major difficulty and intense focus of research for CRS and HIPEC is patient
selection. Curative CRS and HIPEC is only achieved in patients with limited
disease, defined by either the PCI (Peritoneal Carcinomatosis Index) or the
recently introduced PSDSS (Peritoneal Surface Disease Severity Score). A
disadvantage of both scoring systems is that intraoperative assessment of
peritoneal disease is required. Patients with disease that is too extensive do
not undergo CRS and HIPEC resulting in 23.4% unnecessary explorative
procedures. Preoperative imaging does not accurately deflect the amount of
peritoneal metastases. CT alone has poor sensitivity of 11% for nodules smaller
than 0,5 centimetres. Also radiological PCI scores significantly underestimate
intraoperative PCI.

Second major field of interest is to improve detection of recurrent disease
after CRS and HIPEC with curative intent. A recent study presented 46%
recurrence rate after a median disease-free survival of 11.4 months.
Recurrences were locoregional (43%), distant metastases (26%) or both (31%).
Optimal treatment of recurrent locoregional disease is repeat CRS and HIPEC,
extending median survival with 43 months.
Postoperative follow-up of patients after HIPEC is routinely performed every
three months with physical examination, laboratory carcinoembryonic antigen
(CEA) tumour marker levels and biannual CT-scan of abdomen, liver and lungs.
CEA, however, has poor sensitivity (30-40%) or specificity (87%) for detection
of recurrence. Normal CEA values may be found in almost 50% of cancers before
surgical resection and often do not rise during recurrences1. CEA elevation
also has a slow lead time predating the clinically identifiable recurrence by
approximately 5 months.
Imaging by (PET)/CT or MRI does not accurately detect PC unless advanced stage
of metastases are present. Follow-up with CEA and CT-scan, as is standard, can
often result in late diagnosis of recurrent disease, therefore limiting
treatment options due to either extensive locoregional recurrence or distant
metastases for many patients.



In the past decade studies have been performed evaluating the diagnostic and
prognostic value of free circulating tumour DNA (ctDNA). It is proposed that
ctDNA is released into the circulation and is present in plasma and serum. The
precise mechanism of the release of DNA into the bloodstream remains to be
proven. Accordingly, it is possible to detect ctDNA, such as genetic or
epigenetic alterations identified in the primary tumour DNA, in the serum of
patients with various cancers. Several tumour-specific circulating DNA markers
have been identified to have diagnostic and prognostic value in primary
colorectal cancer. Also ctDNA have been proven valuable for follow-up of
patients after resection of primary colorectal cancer.
In patients with colorectal cancer, ctDNA was detected in 73% of patients and
up to 95% in patients with metastatic disease. In 206 patients with metastatic
colorectal cancer sensitivity of clinically relevant KRAS mutations was 87.2%
with specificity of 99.2%. In healthy patients or in patients with colitis the
level of ctDNA was undetectable. Also in other adenocarcinomas it has been
shown feasible to detect ctDNA; in patients with pancreatic cancer. Detection
of ctDNA after resection predicts recurrence and poor outcome, with recurrence
by ctDNA detected 6.5 months earlier than with CT imaging.

Previous studies have focussed to other types of circulating tumour material
such as circulating tumour cells, or DNA fragments. A major advantage of ctDNA
is its specificity for the mutations which are present in the individual
patient, since specific mutations are looked for in the plasma that have
previously been detected in the solid surgical resection specimens. Therefore
it is less prone to have high false positivity as is the case in DNA fragment
detection. Also ctDNA is technically more feasible for detection in blood
compared to circulating tumour cells.

The value of ctDNA could be a valuable asset as prognostic and diagnostic
marker in patients with peritoneal metastases.
Aim is to investigate the feasibility of ctDNA after cytoreductive surgery and
HIPEC.

To evaluate the detection ctDNA in patients with PC of colorectal origin
undergoing cytoreductive surgery and HIPEC at time of diagnosis in a
feasibility trial

This study is considered feasible:
1. If in at least 70% of the patients ctDNA status correlates with mutational
status of the tissue specimen preoperatively (qualitative)
2. If in at least 50% of the patients with detectable mutated ctDNA show
decreased levels of ctDNA after treatment (quantitative)


If this study has proven feasible, a prospective multicenter cohort study will
be proposed.

Feasibility study. VU University Medical Centre.
Two blood samples (2*9ml Streck tubes per moment) are taken during a period of
several weeks


Preoperative
- Venous blood sample (18mL) (after anaesthesia, taken from central venous
line before first surgical incision)

Early postoperative
- Venous blood sample (18mL) 2-4 weeks postoperative

Potential issue of concern is the very small chance of a complication following
venapunction. These include:
- Excessive bleeding
- Fainting of feeling light-headed / venapunction related anxiety
- Hematoma or blood accumulating under the skin
- Pain