Personalised Medicine in Colorectal Cancer?

Mr Arfon G M T Powell MB ChB MSc MRCSEdClinical Research Fellow in Surgery

Colorectal cancer is the third most common cancer in the UK

39,991 new cases in 2008

Cancer Reseach UK. Bowel cancer statistics – UK, 2011. http://info.cancerresearchuk.org/cancerstats/types/bowel/

• CRC is the 2nd most common cause of cancer-death• Accounting for 16,259 deaths in 2009

Cancer Mortality - UK statistics 2009

Lungs 22%

Bowel 10%

Breast 8%

Prostate 7%

Others 53%

Cancer Reseach UK. Cancer Mortality – UK Statistics 2011. http://info.cancerresearchuk.org/cancerstats/mortality/

Treatment

• Treatment regimens are currently based on disease stage

• Surgery• Chemotherapy– Curative– Palliative

• Biological therapy

Prognosis

• Prognosis still remains stage dependent– Dukes’ A 93%– Dukes’ B 77%– Dukes’ C 48%

Cancer Reseach UK. Bowel cancer statistics – UK, 2011. http://www.cancerresearchuk.org/cancer-help/type/bowel-cancer/treatment/statistics-and-outlook-for-bowel-cancer#outlook

http://www.hopkinscoloncancercenter.org/CMS/CMS_Page.aspx?CurrentUDV=59&CMS_Page_ID=1F7C07D4-268D-4635-8975-70A594870CC8

Surgical approach to colorectal cancer

Variation in biomarker prognostic value

Colorectal cancer development

• Accumulation of genetic alterations – Vogelstein

Microsatellite Instability Phenotype

• Distinct genomic instability pathway • Microsatellite repeats • Associated with loss of mismatch repair

protein (MMR) function• Improved outcome

Söreide K, Janssen EA, Söiland H, Körner H, Baak JP. Microsatellite instability in colorectal cancer. Br J Surg 2006; 93:395-406.

CpG Island Methylator Phenotype

Hypermethylation of cytosine- and guanine-rich stretches of DNA, called CpG islands, in the promoter region of genes causes transcriptional silencing and has been implicated in carcinogenesis

MSI/CIMP+

MSI/CIMP-Microsatellite stability status

CIMP status

CIMP status

CIMP +ve

CIMP -veMSI

MSS

MSS/CIMP+

MSS/CIMP-

CIMP +ve

CIMP -ve

MSI/CIMP+

MSI/CIMP-Microsatellite stability status

CIMP status

CIMP status

CIMP +ve

CIMP -veMSI

MSS

MSS/CIMP+

MSS/CIMP-

CIMP +ve

CIMP -ve

Good survival

Poor survival

MSI/CIMP+

MSI/CIMP-Microsatellite stability status

CIMP status

CIMP status

CIMP +ve

CIMP -veMSI

MSS

MSS/CIMP+

MSS/CIMP-

CIMP +ve

CIMP -ve

Prognostic information remains unclear

Serrated Adenocarcinoma

• Proximal location• MSI positive• Outcome variable which depends on tumour

site

http://kathrin.unibas.ch/polyp/bilder/gross/p015-03.jpg

Serrated AdenocarcinomaNon Serrated Adenocarcinoma

Our experience with performing MSI and CIMP status analysis on

colorectal tumours

Study design

• Retrospective study of 750 FFPE tumours• IHC for MMR proteins (MLH1, MSH2, MSH6 and PMS2)• 40% tumour required within the section for PCR• MSI PCR analysis of:– BAT 25– BAT 26– MONO 27– NR-21– NR-24

Technical issues

• 55% of patients required macroscopic dissection to the equivalent of 2 10micron sections

Technical issues

• 55% of patients required macroscopic dissection to the equivalent of 2 10micron sections

MSI +ve

MSI -ve

Preliminary results on 233 patients• Not significantly associated with:

– Increasing age (P=0.168)– Dukes stage (P=0.054)– Poor differentiation (P=0.362)– Vascular invasion (P=0.176)– Anaemia (P=0.192)– Raised CRP (P=0.374)– Hypoalbuminaemia (P=0.541)– Emergency presentation (P=0.943)

• Significantly associated with:– Right colon location (P<0.001)– Polypoid morphology (P=0.031)– Lower lymph node ratio (P=0.040)– Mucin production (P=0.009)– Serrated adenocarcinoma (P<0.001)

P=0.042

The relationship between MSI status and cancer-specific survival

CIMP study design

• Extracted DNA requires bisulfite conversion

• Followed by a methylight PCR assay for– CACNA1G– IGF2– NEUROG1– RUNX3– SOCS1

DNA recovery following bisulfite treatment

• DNA recovery following bisulfite treatment is variable and does not reach the projected > 75%

Patient Input (ng) nano drop (ng/ul) DNA recovered (ng) Percentage recovered (%)

1 350 3.9 78 22.3

2 350 4.3 86 24.6

3 350 2.8 56 16.0

4 350 28 560 160.0

5 350 2.5 50 14.3

6 350 3.4 68 19.4

7 350 3.7 74 21.1

8 350 3.4 68 19.4

9 200 0.3 6 3.0

10 300 84 1680 560.0

11 350 1.7 34 9.7

12 200 64 1280 640.0

13 350 3.7 74 21.1

14 300 2.8 56 18.7

15 300 1.5 30 10.0

16 300 4.8 96 32.0

MSI and CIMP status as predictors of response to treatment

TreatmentA

Curative resection surgery

B

C Resection surgery + adjuvant therapy (eg. Chemothearpy)

D Dependent on tumour characteristics

Treatment of colorectal cancer

• Surgery remains the primary modality for cure• Chemotherapy for high risk patients– Lymph node involvement– Locally advanced tumours

• MDT decision• Difficulty identifying patients that benefit from

chemotherapy

Adjuvant Chemotherapy

• 2 major regimens for CRC treatment:– FOLFIRI (5-FU, folinic acid [Leucovorin], and

irinotecan [Campostar]) – FOLFOX (5-FU, folinic acid [Leucovorin], and

oxaliplatin [Eloxatin])

Adjuvant Chemotherapy

• 2 major regimens for CRC treatment:– FOLFIRI (5-FU, folinic acid [Leucovorin], and

irinotecan [Campostar]) – FOLFOX (5-FU, folinic acid [Leucovorin], and

oxaliplatin [Eloxatin])• Results in context of MSI is conflicting

Conclusions

• Colorectal cancer tumour heterogeneity exists• Techniques validated• MSI+/CIMP+ confers improved survival• Response to treatment remains unclear

Acknowledgments

I would like to thank Dr David Baty and Christine Black (Molecular Genetics, Dundee) for their expertise with the MSI analysis

I would like to thank Rachael Ellis (Molecular Genetics, Glasgow) for her help with the bisulfite treatments

I would like to thank Clare Orange for her continued help over the last 3 years!

Thank you!