Confocal Laser Endomicroscopy - Cedars-Sinai · Confocal Laser Endomicroscopy ... MD and Laith H. Jamil, MD 39200 Ortiz_Adv Digest_r2.indd 1 12/15/09 11:46 AM. percent ... as shown

JANUARY 2010

ADVANCES IN DIGESTIVE DISORDERS

Confocal laser endomicroscopy (CLE) is a new tool

for endoluminal imaging of gastrointestinal epithelia.

The technology provides very high-resolution

images of the mucosal layer by illuminating tissue

with a low-power laser and detecting the refl ected

fl uorescent light through a pinhole. CLE is being

used to help detect Barrett esophagus, gastric

cancer, colon polyps and many other conditions.

CLE can be performed with either a dedicated

endoscope or a probe that passes through the

accessory channel of a standard endoscope

or colonoscope. Both devices offer very high

magnifi cations, with resolutions in the range of 0.7

to 1.0 μm, and optical penetration of the epithelium

to a depth of 250 μm, a level of resolution that

rivals light microscopy. CLE also allows real-time,

in vivo histopathological evaluation of suspected

dysplastic and neoplastic epithelial lesions identifi ed

by other optically enhanced imaging modalities

such as narrow-band imaging.

Initial studies using CLE identifi ed epithelial

abnormalities that reliably distinguished high-grade

dysplasia (HGD) in Barrett esophagus and early

esophageal adenocarcinoma from nondysplastic

Barrett epithelium. These abnormalities included

an irregular epithelial lining, dark areas indicating

irregular fl uorescein uptake, and irregular, dilated

vessels. Using these criteria, probe-based CLE

(pCLE) detected HGD and early adenocarcinoma

with sensitivity of 80 percent and specifi city of 94

CONTENTSConfocal Laser EndomicroscopyJeffrey Conklin, MDLaith H. Jamil, MD

Split-Dose of 6-MP/Azathioprine for IBDDavid Q. Shih, MD, PhDMinh Nguyen, MDEric A. Vasiliauskas, MD

Cedars-Sinai Medical CenterDivision of GastroenterologyStephan Targan, MDDirector(310) 423-6056

Cedars-Sinai Medical Center is

ranked among the nation’s top

10 hospitals in gastrointestinal

disorders by U.S.News & World

Report.

Continued on Page 2 (see “CLE”)

Figure 1: A is a histopathological image demonstrating Barrett esophagus with no dysplasia. The surface, columnar epithelial cells are aligned in a neat row with small, basally oriented nuclei. The black arrow points out a goblet cell – the rounded bluish cell – that is the diagnostic feature of intestinal metaplasia of Barrett esophagus. B is a confocal laser endomicroscopy image of the corresponding tissue in vivo. The whiter areas are the lamina propria where fl uorescein is in the highest concentration. Orderly, columnar epithelial cells line the lamina propria as seen in the histopathological image. The white arrow indicates a goblet cell.

Confocal Laser EndomicroscopyGives GIs a Powerful New ToolJeffrey Conklin, MD and Laith H. Jamil, MD

39200 Ortiz_Adv Digest_r2.indd 139200 Ortiz_Adv Digest_r2.indd 1 12/15/09 11:46 AM12/15/09 11:46 AM

percent (Note 1). The positive predictive

value was 44 percent and the negative

predictive value was 99 percent.

In another study, CLE did not outperform

the Seattle biopsy protocol – four quadrant

biopsies every centimeter from the gastro-

esophageal (GE) junction to the Z-line –

as a screening tool for patients at high risk

for HGD or early adenocarcinoma (Note

2). However, the use of CLE signifi cantly

decreased the number of biopsies needed

to obtain the same screening result.

At Cedars-Sinai, we are using CLE to

identify suspicious mucosal lesions for

defi nitive therapy, as shown in the fi rst case

study below. In the second case study, CLE

was used to guide surgical resection when

endoscopy failed to identify a gross tumor

or a suffi ciently clear margin between normal

and abnormal tissue.

Case study 1

A 76-year-old male presented with a 20-

year history of intermittent dysphagia to

solid foods that was not progressive. He

never complained of heartburn, but for

about a decade suffered from episodic

regurgitation of gastric contents when lying

down after large meals. In late 2008, an

endoscopy revealed an irregular Z-line, and

what was described as a small “pyramidal”

lesion just below the GE junction. Biopsies

of this lesion were interpreted as high-grade

dysplasia arising in Barrett esophagus. After

a work-up (including endoscopic ultrasound

and PET/CT scan) was negative for invasive

esophageal adenocarcinoma, he was

referred to Cedars-Sinai for treatment.

Endoscopy demonstrated short salmon

colored tongues of mucosa and a small

area of “lumpy-bumpy” mucosal change just

below the squamocolumnar junction. The

patient was given intravenous fl uorescein,

and the irregular area and other parts

of the Barrett mucosa were examined

with the CLE probe. Intestinal metaplasia

without dysplasia (Figure 1) was identifi ed.

High-grade dysplasia was present in the

suspicious area and at another location

where no mucosal irregularity had been

identifi ed with narrow-band imaging

(Figure 2). These areas were injected with

a mixture of epinephrine and saline, and

removed piecemeal using a Duette device.

Pathological examination of the tissue

revealed “two foci of high-grade dysplasia,

probably arising in a background of Barrett

esophagus.”

Case study 2

A 68-year-old male with vague upper GI

complaints underwent an endo-gastro-

duodenoscopy (EGD) with random biopsies,

which showed evidence of adenocarcinoma.

A PET CT was negative, so a repeat EGD

was performed with the goal of pinpointing

the location and the periphery of the tumor.

No gross tumor was found, and multiple

biopsies were performed. Pathological

examination of these biopsies revealed

evidence of HGD.

Figure 3: Endoscopic view of the distal body.

Figure 4: pCLE image showing dysplasia.

2 JANUARY 2010 • CEDARS-SINAI ADVANCES IN DIGESTIVE DISORDERS

CLE: continued from Page 1

Figure 2: A is a histopathological image demonstrating Barrett esophagus with high-grade dysplasia. The surface epithelial cells are not in neat rows. Their nuclei are large, of various shapes, with an irregular chromatin pattern and appear to be stacked up or stratifi ed. The black arrow points out a mitotic fi gure. B is the CLE image of the corresponding tissue in vivo. The large, dark and jumbled cells in the center of the image are dysplastic cells that do no take up fl uorescein well.


The patient was then referred for a third

EGD to identify the margins of dysplasia for

surgical resection. As before, the procedure

found no gross malignant abnormality, but

did reveal somewhat more prominent and

erythematous folds 10 cm below the GE

junction and distally (Figure 3).

At this time, pCLE was employed to

examine the area of the gastric body and

the antrum very carefully. In the antrum,

we noted multiple areas of complete

disorganization and loss of structures in the

tissue, suggestive of dysplasia (Figure 4).

An area of normal pattern of gastric glands

was noted approximately 10 cm below the

GE junction and proximally (Figure 5). This

normal-appearing area was injected in two

locations with tattoo spot injection to serve

as a clear margin to cut during surgery.

Subsequently, the patient underwent

distal gastrectomy at the margins of the

tattoo, omentectomy and reconstruction

by retrocolic Billroth II gastro-jejunostomy.

Pathological examination noted minute

focus of HGD involving the antrum, with the

proximal margins negative for dysplasia or

metaplasia.

Dr. Conklin is Medical Director of the Esophageal Program at [email protected]

Dr. Jamil is Associate Director of Interventional Endoscopy at [email protected]

CEDARS-SINAI ADVANCES IN DIGESTIVE DISORDERS • JANUARY 2010 3

Azathioprine (AZA) and 6-mercaptopurine

(6-MP) have been shown to be effective

in treating infl ammatory bowel disease

(IBD). These thiopurines are generally well-

tolerated, continue to be widely utilized,

and remain a cornerstone of IBD therapy

despite the introduction of the newer class

of biologic therapeutics.

The utility of 6-MP metabolite monitoring is

increasingly recognized, as determination

of levels can assist clinicians in optimizing

clinical response to thiopurines and allows

for the identifi cation of individuals at

increased risk for drug-induced toxicities.

Prior studies suggest that 6-thioguanine

(6-TGN) metabolite levels correlate with

therapeutic effi cacy in IBD patients, whereas

abnormally high 6-methylmercaptopurine

(6-MMP) levels are associated with dose-

dependent toxicities (see references).

A signifi cant portion of individuals (about

20 percent) with the “normal genotype”

(TPMTH/TPMTH) exhibit preferential 6-MMP

metabolism. When dosed in the traditional

weight-based, once-a-day fashion, patients

with this metabolic phenotype exhibit

high 6-MMP levels, usually in the face of

“subtherapeutic” 6-TGN levels. 6-MP/AZA

dose escalation in this subset of patients –

in an attempt to push the 6-TGN level into

the “therapeutic range” – often results in

dose-dependent leukopenia, transaminitis

and/or fl u-like symptoms (headaches,

nausea, myalgias, fatigue, general malaise).

Such patients are often deemed “partial

responders,” in that the dose that leads

to adequate control of IBD symptoms

also causes the aforementioned toxicities.

Overproduction of 6-MMP and side-effects

resolve with dose reduction, but the lower

dose often fails to adequately suppress

disease activity, resulting in suboptimal,

partial symptom control. The management

of this subset of IBD patients thus remains a

signifi cant challenge to gastroenterologists.

Anecdotally, we observed that simply

splitting the daily dose of thiopurine (e.g.

50 mg BID rather than 100 mg once daily)

can reduce the 6-MMP metabolites while

maintaining 6-TGN levels. This observation

inspired a retrospective chart review

(IRB #Pro00014002) of patients with

baseline 6-MMP levels greater than 7,000

pmol/8×108 RBC who underwent split

dosing (n=16).

Dividing the daily thiopurine dose led to

a signifi cant reduction in 6-MMP levels

(11,879 vs. 5,955 pmol/8×108 RBC;

p=0.0001) without adversely affecting

clinical disease activity or 6-TGN

levels (250 vs. 227 pmol/8×108, p=NS)

(Figure 1). Side effects associated with

6-MMP, such as increased liver function test

(LFT), leukopenia and fl u-like symptoms,

improved in seven of eight patients. After

mean follow-up of 42 months, seven of the

Split-Dose of 6-MP/Azathioprine to Manage IBD Patients with Preferential 6-MMP MetabolismDavid Q. Shih, MD, PhD; Minh Nguyen, MD; Eric A. Vasiliauskas, MD

Figure 5: pCLE image showing a normal pattern of gastric glands.

Continued on Page 4 (see “Split-Dose”)

References

1. Pohl H, et al. Miniprobe confocal laser micro-

scopy for the detection of invisible neoplasia in

patients with Barrett esophagus. Gut 57:

1648-1653, 2008.

2. Dunbar KB, et al. Confocal laser endo-

microscopy in Barrett esophagus and

endoscopically inapparent Barrett neoplasia.

Gastrointest Endosc. 70: 645-654, 2009.


Division of Gastroenterology • 8730 Alden Dr., 2nd Floor East • Los Angeles, CA 90048(310) 423-6056 • Fax (310) 423-0125 • www.cedars-sinai.edu

16 patients were able to be maintained on a split dose of 6-MP with control of

their IBD.

To our knowledge, this is the fi rst study to demonstrate the effectiveness of dose

splitting on preferential metabolism. This novel approach has several advantages

over other commonly employed strategies. Dose splitting does not sacrifi ce

potential effi cacy associated with dose reduction, and may even allow for further

upward titration of thiopurine to effi cacy if needed. It avoids the introduction of

possible additional medication side effects as can be seen with co-administration

of allopurinol and the potential cost burden of designer biologic inventions. This

maneuver is relatively simple for both patients and practitioners alike.

Split-dose administration of 6-MP/AZA rather than traditional single daily dosing

represents a safe and effective treatment option for IBD patients with preferential

6-MMP metabolism who might otherwise not tolerate immunomodulator therapy

and require ongoing steroid exposure and escalation of therapy to biologics, other

immunosuppressives or surgery.

References:

1. Dubinsky MC, et al. Pharmacogenetics and metabolite

measurement for 6-mercaptopurine therapy in

infl ammatory bowel disease. Gastroenterology 2000;

118:705-13

2. Shaye, Omid, et al. Hepatotoxicity of

6-mercaptopurine (6-MP) and azathioprine (AZA)

in adult IBD patients. Am J Gastroenterol 2007;

102:2488–2494.

3. Sandborn W, et al. Azathioprine or 6-mercaptopurine

for inducing remission of Crohn’s disease. Cochrane

Database of Systemic Reviews 2000: CD000545.

4. Mardini, HE, et al. Utility of measuring

6-methylmercaptopurine and 6-thioguanine nucleotide

levels in managing infl ammatory bowel disease

patients treated with 6-mercaptopurine in clinical

practice setting. Journal of Clinical Gastroenterology

2003; 36(5):90-5.

5. Gearry, RB and Barclay, ML. Azathioprine and

6-mercaptopurine pharmacogenetics and metabolite

monitoring in infl ammatory bowel disease. Journal of

Gastroenterology and Hepatology 2005; 20:1149-57.

Dr. Shih (left) is Assistant Director of Basic Research at Cedars-Sinai’s Infl ammatory Bowel and Immunobiology Research Institute. Dr. Nguyen (center) is a researcher in the Division of Gastroenterology and an internal medicine resident in the Department of Medicine at Cedars-Sinai. Dr. Vasiliauskas (right) is Associate Clinical Director of the Infl ammatory Bowel and Immunobiology Research Institute. [email protected], [email protected], [email protected]

Split-Dose: continued from Page 1


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Confocal Laser Endomicroscopy - Cedars-Sinai · Confocal Laser Endomicroscopy ... MD and Laith H. Jamil, MD 39200 Ortiz_Adv Digest_r2.indd 1 12/15/09 11:46 AM. percent ... as shown