Abstract
Window-of-opportunity, presurgical models have been proposed to assess the activity of candidate preventive agents in a cost-effective manner and to characterize their mechanisms of action (1). This approach offers the opportunity to test the activity of drugs on cancer and the surrounding pre-malignant and normal tissue present in the surgical specimen thus providing important tissue based biomarker information as to whether an agent should proceed to a large phase III trial.
Here we provide three examples of presurgical trials that are currently underway in breast cancer, prostate cancer and colorectal adenomas to characterize the preventive potential of candidate agents.
In breast cancer, most studies use tumor Ki-67 labeling index (LI) as the main surrogate biomarker inasmuch as the decrease in this proliferation-related antigen after short-term neoadjuvant treatment has shown prognostic significance on progression free and overall survival in several studies (2,3). Our group has used this model to assess the minimal active dose of tamoxifen in ER-positive breast cancer that led to the implementation of phase IIb and phase III prevention trials of tamoxifen at 5 mg/day (4).
Importantly, the presurgical model may provide insight into the drug's preventive potential against tumor adjacent dysplastic (or intraepithelial neoplastic) cells and distant ductal hyperplastic cells. The concept of field cancerization is well documented in breast cancer (5), and recent studies have shown that Ki-67 LI is positively associated with likelihood of malignant transformation from ductal hyperplasia to ductal intraepithelial neoplasia (6) and its level of staining in atypical lesions in core biopsies may predict breast cancer risk, going from a 10-year cumulative incidence of breast cancer of 3% for lesions with Ki-67 LI <2% to 14% in those with Ki-67 LI ≥2% (7).
We have recently conducted a randomized, window-of opportunity trial of lapatinib (8), a reversible tyrosine kinase inhibitor which targets both HER-2 and EGFR tyrosine kinases, administered for 3 weeks prior to surgery at 1500 mg once daily or matching placebo in women with treatment naïve T1-2, N0-1, HER-2+ve breast cancer (IHC 3+ and/or FISH+).
Prior to treatment, a core needle biopsy of the primary tumor was performed percutaneously with a 14-gauge needle after the administration of local anaesthetic. A single skin incision with the tip of a #11 scalpel was performed before the biopsy. At the time of surgical removal of the tumor, three to five specimens of adjacent (within 1 cm from the tumor) and distant (more than 1 cm form the tumor) grossly normal tissue (i.e., the surgical margins of quadrantectomy or lumpectomy, or the grossly free quadrants from mastectomy specimens) were obtained to assess systematically the prevalence of DIN and ductal hyperplasia. Specifically, the prevalence of DIN was evaluated in samples both adjacent and distant from the tumor, whereas the prevalence of ductal hyperplasia was evaluated exclusively in samples distant from the tumor.
The prevalence of DIN was 70% in the lapatinib arm and 76% in the placebo arm (p=ns), and the corresponding median (range) Ki-67 LI was 15% (5-35) in the lapatinib arm versus 20% (5-60) in the placebo arm (p=0.06). Likewise, the prevalence of ductal hyperplasia was 96% and 93%, and the median Ki-67 LI was 1% (1-7) versus 3% (1-5) in the lapatinib and placebo arms, respectively (p=0.006). These data support the notion that this model can be used to assess the preventive activity of new agents.
In prostate cancer, we have recently completed a study of finasteride versus flutamide at a low dose versus placebo in patients candidates to radical surgery for a diagnosis of prostate cancer (9). The study was a prospective randomized, phase IIB, placebo controlled, double-blind, presurgical trial of finasteride 5 mg day vs. flutamide 250 mg day versus placebo in men with PCa. Patients with a biopsy diagnosis of PCa, clinical stage ≤T2, and candidates to radical retropubic prostatectomy were enrolled. A biopsy was considered acceptable if a minimum of 10 cores were evaluable. The drugs and placebo were administered in a double-blinded fashion, beginning 4 to 6 weeks before and protracted until the day before surgery. The primary endpoint of the study was to test the effect of finasteride and flutamide in comparison to placebo, on normal, dysplastic and malignant tissue in subjects with PCa in order to get insight into the biomarker modulation by these agents. A total of 125 patients were randomized. The study primary endpoint was the reduction in mean nuclear area in cancer tissue and/or in HG-PIN tissue and in the normal tissue in the two treatment groups (flutamide and finasteride) compared with the placebo arm. Preliminary data show in the placebo group that 75% of the cases had a higher discriminant function score of karyometric features at the end of study with a significant increase of the mean score by 90%, whereas the flutamide treated PCa cases had increased discriminant function scores by a mean of 50% in 79%. The finasteride treated PCa cases had increased discriminant function scores in 50% of the case, with a net increase in the mean score by only 8%.
As regards colorectal carcinogenesis, adenomas are well recognized colorectal cancer risk markers, and regression of adenomas through chemopreventive strategies may reduce the incidence of cancer. Inflammation and oxidative stress appear to play a crucial role in the development of CRC (10), and interference with the mechanisms inducing oxidative stress and possibly cancer progression may represent a new strategy in CRC chemoprevention. Allopurinol, an antigout agent, is an inhibitor of xanthine oxidoreductase and inhibits the generation of uric acid as the final product of purine catabolism, as well as the resulting generation of superoxide in humans. Studies have revealed the role of elevated uric acid levels and the associated oxidative stress in a broad spectrum of pathological conditions, including cancer (11). To assess the effects of allopurinol on cell proliferation in both adenomatous and unaffected colonic tissue, we designed a randomized phase I/II, double blind, placebo-controlled, multicenter trial in patients with colorectal adenomatous polyps (12). After a complete colonoscopy and biopsy of the index polyp, subjects with histologically confirmed adenomas were assigned to either placebo or two doses of allopurinol (100 mg or 300 mg) and treated for 4-6 weeks before polyp removal. Samples of normal colonic tissue were also collected on both baseline and end-of-study colonoscopy. Treatment effect on cell proliferation was assessed by measuring changes of Ki-67 labeling index (primary endpoint: Ki-67 % change) on both adenomatous and normal colonic tissue. Secondary endpoints included treatment modulation of biomarkers of oxidative activation (NF-Kb and b-catenin), apoptosis (topoisomerase-II-a, Cox-3, Bcl-2), inflammation (u-CRP) and of circulating IGFs (IGF-1, IGFBP-3). Enrolment stopped on July 1st, 2010 with a total of 73 subjects enrolled. Preliminary data showed a 98% treatment compliance, with only 3 G1 adverse events (1 leg cramps, 1 erythema and 1 skin rush), confirming the high safety of allopurinol.
In conclusion, our data indicate the feasibility of the window of opportunity, presurgical model to assess the preventive potential of candidate agents in a cost-effective manner. Further molecular profiling for characterization of the dysplastic and hyperplastic tissue will enable us to understand whether the same changes seen in the tumor tissue are present in the normal tissue and whether there is a field effect where the adjacent tissue is similar to the cancer tissue.
References:
1. Kelloff GJ, et al. Progress in cancer chemoprevention: Perspectives on agent selection and short-term clinical intervention trials. Cancer Res 1994; 54(7 Suppl):2015s-2024s.
2. Dowsett M, et al. Prognostic value of Ki67 expression after short-term presurgical endocrine therapy for primary breast cancer. J Natl Cancer Inst 2007; 99:167-170.
3. Decensi A, et al. Prognostic significance of Ki-67 labeling index after short-term presurgical tamoxifen in women with ER-positive breast cancer. Ann Oncol. 2010 Aug 17.
4. Decensi A, et al. A randomized trial of low-dose tamoxifen on breast cancer proliferation and blood estrogenic biomarkers. J Natl Cancer Inst 2003; 95:779-790.
5. Heaphy CM, et al. Mammary field cancerization: molecular evidence and clinical importance. Breast Cancer Res Treat 2009; 118:229-239.
6. Shaaban AM, et al. Breast cancer risk in usual ductal hyperplasia is defined by estrogen receptor-alpha and Ki-67 expression. Am J Pathol 2002; 160:597-604.
7. Santisteban M, et al: Ki67: a time-varying biomarker of risk of breast cancer in atypical hyperplasia. Breast Cancer Res Treat 2010; 121:431-437.
8. DeCensi A, et al. Randomized phase II trial of preoperative lapatinib versus placebo in HER2-positive breast cancer. J Clin Oncol 28:15s, 2010 (suppl; abstr 576).
9. Maffezzini M, et al. Randomized pre-surgical trial of finasteride vs flutamide vs placebo in prostate cancer. AACR Frontiers in Cancer Prevention Research 2010. Control/Tracking Number Abstract 10-A-155-AACR.
10. Kraus S, et al. Inflammation and colorectal cancer. Curr Opin Pharmacol. 2009;9:405-10
11. Rennert G et al. Allopurinol Use and Colorectal Cancer Risk. AACR 3rd International Conference on Frontiers in Cancer Prevention Research 2004, Abstract #C88.
12. Puntoni M, et al. Randomized, presurgical study of allopurinol vs. placebo in subjects with colorectal adenomas. AACR Frontiers in Cancer Prevention Research 2010. Control/Tracking Number Abstract 10-A-153-AACR.
Citation Information: Cancer Prev Res 2010;3(12 Suppl):ED05-04.
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