Abstract 1779: CYP2W1 as a novel therapeutic target in colon cancer

Colorectal cancer is the third most frequently diagnosed malignancy in both men and women and a leading cause of cancer-related deaths in the Western world. Advances in neoadjuvant/adjuvant chemotherapy (including 5-fluorouracil, irinotecan, and oxaliplatin) as well as radiation therapy have improved the clinical outcome, however, the overall impact of these amended treatment regiments has been relatively modest, leaving metastasised or recurrent disease largely incurable by conventional approaches and requiring the development of better therapeutics. Targeted chemotherapy aimed towards more effective advanced colon cancer treatment could be achieved by the use of agents that are systemically inactive but selectively converted to potent cytotoxins locoregionally. We have shown cytochrome P450 2W1 (CYP2W1) to be overexpressed in colorectal cancer, and recently shown this enzyme to be a druggable target in a proof-of-concept study using CYP2W1-transfected colon cancer cells [selected references below]. At this meeting we will present an update on our progress on re-engineering the duocarmycin family of compounds for CYP2W1-targeting. New findings reveal that subtle changes in the duocarmycin pharmacophore can lead to dramatic changes (> 100-fold) in the anti-cancer activity. This drop in anticancer activity of small molecules such as ICT2726 means these can be used as biomarker to detect CYP2W1 functional activity, which can be used alongside immunological methods to characterise malignant colorectal tissue. Similarly, interrogation of R and S-enantiomers of duocarmycin bioprecursors also reveal significant differential anticancer activity in vitro. Studies are currently underway to understand if this differential activity is also observed in CYP2W1-expressing colon cancer xenografts and the results will be presented at the AACR meeting. Our findings reveal the opportunities in targeting CYP2W1 as a novel therapeutic approach in colon cancer chemotherapy.

[1] Travica S. et al. Colon cancer-specific cytochrome P450 2W1 converts duocarmycin analogues into potent tumor cytotoxins. Clin. Cancer Res. 2013, 19(11), 2952-61.

[2] Sheldrake et al. Re-engineering of the Duocarmycin Structural Architecture Enables Bioprecursor Development Targeting CYP1A1 and CYP2W1 for Biological Activity. J Med Chem. 2013, 56 (15), 6273-7.

[3] Stenstedt, K. et al. Cytochrome P450 2W1 polymorphism: functional aspects and relation to risk for colorectal cancer. Pharmacogenomics. 2013, 14(13), 1615-1622.

[4] Sutherland M. et al. Anti-tumor Activity of a Duocarmycin Analogue Rationalised to be Metabolically Activated By Cytochrome P450 1A1 in Human Bladder Cancer. Mol Cancer Ther. 2013, 12 (1), 27-37.

[5] Pors K. et al. Modification of the duocarmycin pharmacophore enables CYP1A1 targeting for biological activity. Chem. Commun., 2011, 47, 12062-4.

[6] Stenstedt K et al. The expression of CYP2W1: a prognostic marker in colon cancer. Anticancer Res. 2012, 32, 3869-74.

Citation Format: Klaus Pors, Paul M. Loadman, Sandra Travica, Steven D. Shnyder, Mark Sutherland, Helen Sheldrake, Mark Searcey, Inger Johansson, Souren Mkrtchian, Magnus Ingelman-Sundberg, Laurence H. Patterson. CYP2W1 as a novel therapeutic target in colon cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1779. doi:10.1158/1538-7445.AM2014-1779

CYP2W1 polymorphism: functional aspects and relation to risk for colorectal cancer

Aim: This study aims to investigate the possible association between the risk of colorectal cancer (CRC) and allelic variants of CYP2W1 and their functional properties. Materials & methods: The distribution of three different CYP2W1 alleles (CYP2W1*1, CYP2W1*2 and CYP2W1*6) in 1785 CRC patients and 1761 healthy blood donors was determined using the TaqMan® (Applied Biosystems, CA, USA) allelic discrimination assay or allele-specific amplification. Corresponding gene products (CYP2W1.1, CYP2W1.2 and CYP2W1.6) were expressed in human colon cancer SW480 cells and their activities towards two different substrates, the duocarmycin analogs ICT2706 and ICT2726, were monitored. Results: No significant differences in the distribution of CYP2W1*1, CYP2W1*2 and CYP2W1*6 alleles were found between CRC patients and controls. The CYP2W1.1, CYP2W1.2 and CYP2W1.6 variant enzymes were expressed at the similar levels in the transfected SW480 cells and had comparable kinetics in terms of the metabolism of the duocarmycin ICT2726, as well as in the bioactivation of ICT2706 into a cytotoxic product. Conclusion: These epidemiological data obtained from a large population of CRC patients and controls cannot confirm the previously suggested decreased risk for CRC among carriers of CYP2W1*2. On the molecular level, this conclusion is further supported by the similar catalytic characteristics of the CYP2W1.1, CYP2W1.2 and CYP2W1.6 variants of CYP2W1.

Original submitted 19 March 2013; Revision submitted 15 July 2013

Colorectal cancer-specific cytochrome P450 2W1: intracellular localization, glycosylation, and catalytic activity

Cytochrome P450 2W1 (CYP2W1) is expressed at high levels in colorectal cancer cells. Moreover, we have shown previously that a higher tumor expression is associated with less survival. In this study, we characterize post-translational modification, inverted endoplasmic reticulum (ER) topology, and catalytic activity of CYP2W1. The analysis of colorectal normal and cancer tissues and CYP2W1 overexpressing human embryonic kidney (HEK) 293 cells showed that a fraction of CYP2W1 is modified by N-glycosylation. Bioinformatic analysis identified Asn177 as the only possible glycosylation site of CYP2W1, which was supported by the inability of an N177A mutant to be glycosylated in HEK 293 cells. Analysis of the membrane topology indicated that unlike other cytochromes P450, CYP2W1 in HEK 293-transfected cells and in nontransfected Caco2TC7 and HepG2 cells is oriented toward the lumen of the ER, a topology making CYP2W1 available to the ER glycosylation machinery. Immunofluorescence microscopy and cell surface biotinylation experiments revealed approximately 8% of the CYP2W1 on the cell surface. Despite the reverse orientation of CYP2W1 in the ER membrane, apparently making functional interactions with NADPH-cytochrome P450 reductase impossible, CYP2W1 in HEK 293 cells was active in the metabolism of indoline substrates and was able to activate aflatoxin B1 into cytotoxic products. The study identifies for the first time a cytochrome P450 enzyme with a luminal ER orientation and still retaining catalytic activity. Together, these results suggest the possibility of using CYP2W1 as a drug target in the treatment of colon cancer using antibodies and/or specific CYP2W1 activated prodrugs.

Clinical profile of a new hormone replacement therapy containing 2 mg 17 beta-estradiol and 10 mg dydrogesterone

OBJECTIVE

Patient's acceptability, compliance, and effectiveness of a new sequential hormone replacement regimen containing 2 mg 17beta-estradiol and 10 mg dydrogesterone, were assessed in a 3-month, open, multicentre study involving 110 menopausal women.

METHODS

A specially designed menopause score was used to assess the severity of menopausal symptoms, each symptom being graded at baseline and after 3 months on a four-point scale. Bleeding data were recorded by the patient on a diary card. Serum hormone levels including FSH, LH, E2, P, PRL, DHEA-S, T, SHBG were checked at the initial visit and at the end of the study.

RESULTS

After 3 months of treatment, all but four of the 34 climacteric symptoms investigated showed a significant improvement. There were no significant changes noted in body weight. The average duration and flow of bleeding showed no significant changes during hormone replacement therapy (HRT). There were no serious adverse events related to treatment.

CONCLUSION

The 17beta-estradiol/dydrogesterone combination HRT reduced effectively climacteric symptoms, showed no significant changes in endometrial thickness as determined by transvaginal ultrasonography and provided excellent cycle control.

[Hormone replacement therapy with 17 beta-estradiol dydrogesterone: results of a 3-month open-label study]

Hormone replacement therapy is well known for its beneficial effects on climacteric symptoms and is also used for the prevention of osteoporosis. In a prospective open label study we evaluated the efficacy and safety of hormone replacement therapy with 17 beta estradiol dydrogesterone (Femoston, 17 beta estradiol/continuously and dydrogesterone/sequentially). We observed 704 women who were treated with 17 beta estradiol-dydrogesterone over three months. 448 of the women previously had not used hormone replacement therapy, 224 women had been treated with a different hormone replacement therapy before they were entered into the study; for 20 women this information was not available. The physicians were asked to assess the severity of climacteric symptoms at baseline and after three months of hormone replacement therapy. In addition, the following parameters were evaluated before and at the end of the study: blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, blood glucose, alkaline phosphatase and gamma glutamyltransferase. Twelve women did not tolerate 17 beta estradiol-dydrogesterone and therefore dropped out of the study. Climacteric symptoms clearly improved after treatment with 17 beta estradiol-dydrogesterone. During our open label prospective study, a significant decrease in blood pressure and serum levels of total cholesterol, LDL cholesterol and the LDL/HDL ratio were observed, whereas serum levels of HDL cholesterol increased significantly. Surprisingly, triglyceride levels also decreased significantly. Serum levels of alkaline phosphatase decreased significantly in women who had received a different hormone replacement therapy before they took 17 beta estradiol-dydrogesterone. We conclude that hormone replacement therapy with 17 beta estradiol-dydrogesterone is highly effective and well tolerated. Hormone replacement therapy with 17 beta estradiol-dydrogesterone appears to have a positive effect on blood pressure and the serum lipid profile. We therefore hypothesise that prolonged treatment with 17 beta estradiol-dydrogesterone may reduce morbidity and mortality secondary to cardiovascular diseases.