Abstract P4-08-05: Impact of common polymorphisms of CYP19A1 and UGT2B17 gene deletion on early endocrine-responsive postmenopausal breast cancer

Background Polymorphisms of genes involved in estrogen production have been linked to breast cancer risk, prognosis and treatment response. Polymorphisms of the aromatase gene CYP19A1 influence its activity. The UGT2B17 catalyzes glucuronic acid transfer to a variety of substrates, including steroids and drugs like the aromatase inhibitor exemestane. We investigated the impact of two variants of CYP19A1 (rs10046, rs4646) and the UGT2B17 gene deletion on disease outcome in 125 postmenopausal women operated for ER-positive primary breast cancer enrolled in a randomized pre-surgical trial.

Patients Briefly, upon informed consent, postmenopausal patients with ER-positive breast cancer (stage T1–2, N0–1, M0) eligible for surgery were randomized to receive either exemestane (25 mg/day), or celecoxib (800 mg/day), or placebo for 6 weeks prior to surgery at the European Institute of Oncology (2004-2008). Exemestane showed a significant 10% absolute reduction in Ki67 labeling index compared to the other two arms. Serum and whole blood was taken at baseline and the day before surgery and stored at -80°C until assayed.

Methods DNA was extracted from blood by QIAamp DNA Blood Kits. The CYP19A1 rs1004/rs46466 were analyzed by Taqman genotyping assays in real-time PCR. The UGT2B17 deletion was estimated by copy number assay (Lifetechnologies). Serum estradiol (E2) and estrone (E1) levels were measured by gas chromatography tandem mass spectrometry detection (GS-MS/MS) after liquid-liquid extraction. The lower limit of quantitation were 0.625 pg/mL for estradiol and 1.56 pg/mL for estrone. The association of genetic polymorphisms with “any event” was assessed by the Cox proportional hazards models adjusted for confounders.

Results The genetic polymorphisms did not deviate from Hardy-Weinberg equilibrium (P-value >0.41) and minor allele frequency of rs10046 (A/G), rs4646 (C/A), and UGT2B17Del were 0.45, 0.22, and 0.31, respectively. The rs10046 A and rs4646 C alleles were associated with higher estrogen levels. Carriers of rs10046 AA had median levels of 7.57 pg/ml E2 and 35.9 pg/mL E1 versus 3,9 pg/mL E2 and 27.4 E1 pg/mL in CA/AA genotypes (P<0.003). Carriers of rs4646 CC had 5.6 pg/ml E2 and 30.45 pg/mL E1 versus 3,95 pg/mL E2 and 27.4 E1 pg/mL in CA/AA genotypes (P=0.05 only for E1). After 6 weeks treatment with exemestane, we observed steeper decreases in estrogen levels in the rs10046 AA/rs4646 CC carriers (P=0.02 for E2). After a median follow-up of 7 years we found that women carrying at least one SNP of rs10046 and one SNP of rs4646 had a better prognosis compared with women carrying homozygote wt SNPs (HR=0.44; 95% CI: 0.2-0.99 P=0.049). Similarly, the UGT2B17 deletion was associated with a better prognosis (HR= 0.43; 95% CI: 0.19-0.97; P=0.0439). There was no interaction with pre-surgical or adjuvant treatment.

Conclusions Our analysis confirms previous findings of an association of CYP19A1 rs10046/rs4646 with estrogen levels in postmenopausal women. Interestingly, the carriers of the variants associated with lower estrogen levels at diagnosis had better prognosis. Further genomic profiling in larger trials aimed to enhance tailored treatment efficacy in endocrine-responsive postmenopausal breast cancer are warranted.

Citation Format: Johansson H, Gandini S, Aristarco V, Macis D, Guerrieri-Gonzaga A, Serrano D, Pruneri G, Lazzeroni M, Viale G, Toesca A, Rajasekaran A, Bonanni B, DeCensi A. Impact of common polymorphisms of CYP19A1 and UGT2B17 gene deletion on early endocrine-responsive postmenopausal breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-08-05.

Abstract P4-15-06: Low dose tamoxifen lowers recurrences after mastectomy for in situ neoplasia. Ten-year results of a monoinstitutional study

There is no agreement upon the need of a preventive treatment after breast mastectomy for in situ neoplasia. Low-dose tamoxifen (5 mg/day) has comparable antiproliferative effect than the standard dose of 20 mg/day in biomarker trials and has been shown to halve ipsilateral recurrence in a large cohort of postmenopausal ER positive DCIS treated with breast conserving surgery (Guerrieri-Gonzaga et al., Int J Cancer 2016).

Here we investigated the effect of low dose tamoxifen in patients treated with mastectomy for an in situ neoplasia and followed-up in a single Institution for a median of 10 years.

Our cohort consists of 404 consecutive premenopausal (n=281) or postmenopausal (n=123) women who underwent unilateral mastectomy at the European Institute of Oncology (IEO), with or without nipple preservation, between 1996 and 2011. Patients had a diagnosis of pure LCIS (n=12) or ER positive (ER>1%) DCIS (n=363) or both (n=29) and were treated with tamoxifen 5 mg/day (n=162) or no treatment (n=242) upon medical judgment, patient preference and/or clinical trial assignment. The main subject and tumor characteristics are reported in table 1.

Patient and tumor characteristics No tam (n=242)Low dose tam (n=162)P-valueMedian age, years (IQR)46 (41, 54)47 (42, 51)0.65Premenopausal status (n, %)160 (66)121 (75)0.07Median BMI (kg/m2, IQR)22 (20, 25)22 (20, 24)0.7Breast cancer family history (%)29320.44Histology (LCIS, DCIS, both; %)4/92/42/86/120.01Grading (G1,G2,G3;%)11/59/2918/61/200.04Median ER (%, IQR)90 (70, 95)90 (80, 95)0.005Median PgR (%, IQR)40 (5, 80)68 (25, 90)0.0002Median Ki67 (%, IQR)15 (10, 23)14 (10, 20)0.03Radiotherapy (n, %)95 (39)76 (47)0.13

After a median follow-up of 10 years (range 4-21 years) and a median low dose tamoxifen treatment of 4.9 years (IQR 2.7, 5.0), a total of 85 events were observed (28 in situ, 40 invasive breast cancers, 3 metastatic diseases, 12 other primary cancers, 2 deaths). A total of 36 ipsilateral breast events (23 versus 13 in the no tam versus tam group, respectively), 32 contralateral breast events (22 versus 10 in the no tam versus tam, respectively) and 17 other events (11 versus 6 in the no tam versus tam, respectively) occurred. Overall, eleven deaths (3%) occurred and no endometrial cancers were observed. A time-dependent competing risk model was applied for tamoxifen use and we have shown that low-dose tamoxifen was associated with a 48% reduction on all breast events (adjusted HR=0.52, 95% CI: 0.31–0.88, p=0.01), adjusting for radiotherapy and age.

Although limited by the observational nature of the study, we show for the first time that treatment with low dose tamoxifen is effective and safe in women who underwent mastectomy for non-invasive breast neoplasms and should be taken into consideration as a risk reduction strategy for premenopausal and postmenopausal women with breast intraepithelial neoplasia.

Citation Format: Guerrieri-Gonzaga A, Gandini S, Serrano D, Lazzeroni M, Pruneri G, Varricchio C, Cazzaniga M, Leonardi MC, Galimberti V, Viale G, De Censi A, Bonanni B. Low dose tamoxifen lowers recurrences after mastectomy for in situ neoplasia. Ten-year results of a monoinstitutional study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-15-06.

Abstract P3-10-02: Presence of atypia in ductal lavage and risk of subsequent breast cancer in a prospective study

Background: Atypical hyperplasia is considered a nearly obligate precursor of breast cancer and is associated with a higher risk of developing breast cancer (BC). Attempts to improve early detection of breast cancer and to provide individualized breast cancer risk assessment would greatly benefit from sampling cellular material from the target tissue. Ductal lavage (DL) is a minimally invasive technique which provides adequate material to detect atypical cells in mammary ducts. However, long term data of the association between atypia from ductal lavage and BC risk are lacking. We studied the prevalence of atypia in DL in different risk categories and its ability to predict BC development in women at risk. Methods: From March 2000 to July 2012 we performed DL in a consecutive series of 348 women with median age of 45 years (range 19-74) at increased BC risk based on the following characteristics: 5 yrs Gail model > 1.66% or > 10% probability of BRCA mutation (n = 155), history of contralateral BC (CBC, n = 161), presence of a BRCA pathogenic variant (n = 32). We analyzed the presence of atypical cells in the baseline specimen of ductal lavage and in repeated lavage and observed their evolution during follow-up. Results: The procedure was safe and well tolerated in most women, with pain and disconfort preventing the procedure in 5.4% of subjects. Overall, 126 (36%) women had atypia at baseline, with a prevalence of 32%, 39%, and 41% in the Gail, CBC and BRCA groups, respectively (p = 0.38). The overall prevalence of atypia considering all visits was 44% (range 36-51). After a median follow up of 6 years, cumulative BC events were 8% in women without atypia versus 14% in those with atypia (log-rank p = 0.08). In the highest risk groups (CBC and BRCA pathogenic variants), the number of BC events was 16 (21%) in women with atypia versus 11 (10%) in women without atypia (p = 0.02 after adjustment for age). Conclusions: Our findings suggest that cytologic atypia in the fluid obtained by DL predicts subsequent BC in women at increased risk, providing individual risk assessment. The reversal of atypia in DL should be evaluated as a surrogate biomarker of BC therapeutic prevention.

Supported by: Associazione Italiana per la Ricerca sul Cancro (AIRC), Lega Italina per la Lotta contro i Tumori (LILT), AVON Foundation for Women.

Citation Format: De Censi A, Cazzaniga M, Gandini S, Casadio C, Chiapparini L, Guerrieri-Gonzaga A, Macis D, Veronesi P, Bonanni B. Presence of atypia in ductal lavage and risk of subsequent breast cancer in a prospective study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-10-02.

The prevalence and clinical relevance of tumor-infiltrating lymphocytes (TILs) in ductal carcinoma in situ of the breast

Background

Tumor-infiltrating lymphocytes (TILs) are a robust prognostic adjunct in invasive breast cancer, but their clinical role in ductal carcinoma in situ (DCIS) has not been ascertained.

Patients and methods

We evaluated the prevalence and clinical relevance of TILs in a well annotated series of 1488 consecutive DCIS women with a median follow-up of 8.2 years. Detailed criteria for TILs evaluation were pre-defined involving the International Immuno-Oncology Biomarker Working Group. TILs percentage was considered both as a continuous and categorical variable. Levels of TILs were examined for their associations with ipsilateral breast event (IBE), whether in situ or invasive.

Results

Of the 1488 patients with DCIS under study, 35.1% had <1%, 58.3% 1-49% and 6.5% ≥50% peri-ductal stromal lymphocytes. The interobserver agreement in TILs evaluation, measured by the intraclass correlation coefficient (ICC) was 0.96 (95% CI 0.95-0.97). At univariable analysis, clinical factors significantly associated with TILs (P ≤0.001) were intrinsic subtype, grade, necrosis, type of surgery. Her-2 positive DCIS were more frequently associated with TILs (24% of patients with TILs ≥50%), followed by the triple negative (11%), Luminal B/Her-2 positive (9%) and Luminal A/B subtypes (1%) (P < 0.0001). We did not find any association between TILs as a continuous variable and the risk of IBEs. Likewise, when patients were stratified by TILs percentage (<1%, between 1% and 49.9%, and ≥50%), no statistically significant association was observed (10-year cumulative incidence of IBEs: 19%, 17.3%, and 18.7% respectively, P = 0.767).

Conclusion

TILs occur more frequently in the Her-2 positive DCIS. Although we did not find a significant association between TILs and the 10-year risk of IBE, our data suggest that immunotherapies might be considered in subsets of DCIS patients.

Chemoprevention studies within lung cancer screening programmes

While aggressive tobacco control and help to stop smoking are essential weapons in the fight against lung cancer, screening with low-dose computed tomography (LDCT) in high-risk populations and chemoprevention may also contribute to reducing lung cancer deaths. Persons undergoing LDCT screening are an ideal population to be tested for agents potentially able to prevent the development of lung cancer by the regression of precancerous lesions, which are routinely monitored as part of the screening process. Peripheral subsolid nodules appear as particularly suitable targets, since many are adenocarcinoma precursors.

A study on inhaled budesonide (a potential chemopreventive drug) for 1 year found that the mean size of non-solid lung nodules was significantly reduced over 5 years of follow-up, compared to inhaled placebo, in a population of high-risk individuals with indeterminate lung nodules not requiring immediate specific investigation for lung cancer and detected as part of a lung cancer screening program with LDCT.

A new randomised placebo-controlled phase-II trial to test the ability of aspirin to induce the regression of non-solid and partially solid nodules detected by LDCT screening has been started. The effect of aspirin on a miRNA signature able to predict the presence of both cancer and precancerous lesions in high-risk asymptomatic individuals is also being monitored in the trial. This signature was previously shown to predict the presence of both lung cancer and non-solid lung nodules in asymptomatic individuals.

Long-term effects of inhaled budesonide on screening-detected lung nodules

BACKGROUND

A previously carried out randomized phase IIb, placebo-controlled trial of 1 year of inhaled budesonide, which was nested in a lung cancer screening study, showed that non-solid and partially solid lung nodules detected by low-dose computed tomography (LDCT), and not immediately suspicious for lung cancer, tended to regress. Because some of these nodules may be slow-growing adenocarcinoma precursors, we evaluated long-term outcomes (after stopping the 1-year intervention) by annual LDCT.

PATIENTS AND METHODS

We analyzed the evolution of target and non-target trial nodules detected by LDCT in the budesonide and placebo arms up to 5 years after randomization. The numbers and characteristics of lung cancers diagnosed during follow-up were also analyzed.

RESULTS

The mean maximum diameter of non-solid nodules reduced significantly (from 5.03 mm at baseline to 2.61 mm after 5 years) in the budesonide arm; there was no significant size change in the placebo arm. The mean diameter of partially solid lesions also decreased significantly, but only by 0.69 mm. The size of solid nodules did not change. Neither the number of new lesions nor the number of lung cancers differed in the two arms.

CONCLUSIONS

Inhaled budesonide given for 1 year significantly decreased the size of non-solid nodules detected by screening LDCT after 5 years. This is of potential importance since some of these nodules may progress slowly to adenocarcinoma. However, further studies are required to assess clinical implications.

CLINICAL TRIAL NUMBER

NCT01540552.

Association of molecular subtypes with Ki-67 changes in untreated breast cancer patients undergoing pre-surgical trials

BACKGROUND

Ki-67 is increasingly being used as a response biomarker in window of opportunity, pre-surgical trials for breast cancer patients. Since Ki-67 is often higher at surgery than at baseline core biopsy in subjects allocated to placebo, we investigated which factors affected this change.

PATIENTS AND METHODS

We retrieved data from 274 patients who received no active treatment in three consecutive pre-surgical trials from a single institution. We assessed the association between changes in Ki-67 from diagnostic biopsy to surgical specimen and the following factors: age, body mass index, tumor prognostic and predictive factors, including immunohistochemical molecular subtype, number and size of biopsy specimens, time from biopsy to surgery, circulating insulin-like growth factor-I, sex hormone-binding globulin and hsCRP.

RESULTS

A total of 269 patients with paired measures of Ki-67 at biopsy and surgery were analyzed. Overall, the mean (±SD) change was 2.2 ± 9.2% after a median interval of 41 days (inter-quartile range 33-48). Molecular subtype was the only factor associated with a significant change of Ki-67 (P = 0.004), with a mean absolute increase of 5.3% [95% confidence interval (CI): 2.3-8.3, P = 0.0005] in estrogen receptor-negative HER2-positive tumors (n = 36) and 5.4% (95% CI: 2.9-7.9, P < 0.0001) in triple-negative tumors (n = 78). No significant change in luminal-A (n = 46), luminal-B (n = 85) and luminal-B HER2-positive (n = 24) tumors was observed.

CONCLUSIONS

A significant increase in Ki-67 from baseline biopsy to end point surgery in untreated subjects was ascertained in HER2-positive and triple-negative tumors. This biological association suggests a real increase in cancer proliferation, possibly as a result of a biopsy-driven wound healing effect, and should be considered in the design and interpretation of pre-surgical studies.

REGISTERED CLINICAL TRIAL NUMBERS

ISRCTN86894592; ISRCTN16493703.

Effect of low-dose tamoxifen after surgical excision of ductal intraepithelial neoplasia: results of a large retrospective monoinstitutional cohort study

BACKGROUND

Postsurgical treatment of ductal intraepithelial neoplasia (DIN) with standard doses of tamoxifen has not reached a consensus yet. Given positive results of low-dose tamoxifen on breast cancer biomarkers modulation, we analyzed a large cohort of DIN patients treated with low-dose tamoxifen or no treatment as per institutional guidelines.

PATIENTS AND METHODS

All consecutive women operated on at the European Institute of Oncology for estrogen receptor (ER)-positive DIN (474 treated with low-dose tamoxifen and 509 untreated patients) were followed up for a median of 7 years.

RESULTS

Compared with untreated patients, a significant 30% reduction in breast cancer risk was observed on low-dose tamoxifen with an adjusted hazard ratio (HR) = 0.70 [95% confidence interval (CI) 0.51-0.94], with a greater benefit in postmenopausal (HR = 0.57; 95% CI 0.34-0.94) than in premenopausal women (HR = 0.79; 95% CI 0.54-1.17). Treated patients with ER and progesterone receptor (PgR) >50% DIN had a lower incidence of breast events than untreated ones (HR = 0.61; 95% CI 0.40-0.94), whereas no protective effect has been observed in patients with ER or PgR <50% DIN. Drug discontinuation resulted in a doubled risk of recurrence in premenopausal women only (HR = 1.95; 95% CI 0.98-3.89). No excess of endometrial cancer occurred.

CONCLUSIONS

Low-dose tamoxifen is a promising and safe strategy for highly endocrine responsive DIN. Treatment adherence is crucial in premenopausal women. A definitive trial is ongoing.

Tailoring treatment for ductal intraepithelial neoplasia of the breast according to Ki-67 and molecular phenotype

Background:

The post-surgical management of ductal intraepithelial neoplasia (DIN) of the breast is still a dilemma. Ki-67 labelling index (LI) has been proposed as an independent predictive and prognostic factor in early breast cancer.

Methods:

The prognostic and predictive roles of Ki-67 LI were evaluated with a multivariable Cox regression model in a cohort of 1171 consecutive patients operated for DIN in a single institution from 1997 to 2007.

Results:

Radiotherapy (RT) was protective in subjects with DIN with Ki-67 LI ≥14%, whereas no evidence of benefit was seen for Ki-67 LI <14%, irrespective of nuclear grade and presence of necrosis. Notably, the higher the Ki-67 LI, the stronger the effect of RT (P-interaction <0.01). Hormonal therapy (HT) was effective in both Luminal A (adjusted hazard ratio (HR)=0.56 (95% CI, 0.33–0.97)) and Luminal B/Her2neg DIN (HR 0.51 (95% CI, 0.27–0.95)).

Conclusion:

Our data suggest that Ki-67 LI may be a useful prognostic and predictive adjunct in DIN patients. The Ki-67 LI of 14% could be a potential cutoff for better categorising this population of women at increased risk for breast cancer and in which adjuvant treatment (RT, HT) should be differently addressed, independent of histological grade and presence of necrosis.

Abstract PD06-06: RELATIONSHIP BETWEEN MOLECULAR SUBTYPE AND CHANGE IN KI-67 IN THE PLACEBO ARMS OF WINDOW OF OPPORTUNITY TRIALS

Background: Window-of-opportunity (WOP), presurgical models often use Ki-67 labeling index (LI) as the main surrogate biomarker for screening therapeutic activity of candidate agents and characterize their mechanism of action. Ki-67 LI in the placebo arm has been frequently reported to be higher at surgery than at baseline biopsy in WOP studies, a finding that has been ascribed to the higher proliferative activity in the tumor edge of surgical specimens that cannot be detected in the baseline core biopsy. Since this observation has important implications in sample size calculation and effect interpretation, we investigated which factors affected the changes of Ki-67 LI in a series of patients allocated to the placebo arms of a number of WOP trials carried out at IEO.

Methods: Data from 181 patients with pT1-2 invasive breast cancer from the placebo arms of three WOP randomized trials were pooled with those of 98 untreated patients, who had a diagnostic core biopsy preceding surgery but declined participation to the study or were ineligible for histological characteristics. Ki-67 LI was measured by evaluating the prevalence of neoplastic cells showing any definite nuclear immunostaining with the Mib-1 monoclonal antibody, in the whole invasive component of baseline core biopsies and in at least 2000 invasive neoplastic cells of surgical samples, in accordance to the recently licensed international recommendations.

Results: We collected data of 273 breast cancer patients with information on the changes in Ki-67 LI: 46 (17%) were Luminal A, 85 (31%) Luminal B/HER2−, 24 (9%) Luminal B/HER2+, 38 (14%) HER2+ and 81 (30%) Triple Negative (TN). Median (IQR) Ki-67LI at baseline in each molecular subtype was 10% (7–11), 20% (16–29), 28% (22–35), 30% (25–45) and 50% (32–75) in the Luminal A, Luminal B/HER2−, Luminal B/HER2+, HER2+ and TN, respectively. Median (IQR) age was 50 years (44–60), median BMI was 24 (22–27), 50% were post-menopausal. The median (range) time elapsed from biopsy to surgery was 41 days (33–48). Overall, the median change in Ki-67 LI between baseline biopsies and surgical samples was 0 (IQR, −2, 5). Results from multivariate analysis showed that none of the factors investigated, including patient and tumor characteristics, time elapsed from biopsy to surgery and circulating biomarkers (IGF-I, SHBG and ultrasensitive CRP) were associated with the Ki-67 LI change except for the immunohistochemically defined molecular subtype, which explained most of the variability of the changes (p = 0.004). As a matter of fact, we observed a 5%, significant increase of Ki-67 LI both in HER2+ and TN tumors, after adjustment for baseline values.

Abstract PD04-07: The Ki-67 labeling index predicts the risk of recurrence of DIN patients treated with radiotherapy following breast conserving surgery

Purpose: To investigate the prognostic relevance of Ki-67 labeling index (LI) in patients with Ductal Intraepithelial Neoplasia (DIN) of the breast.

Patients and Methods: From January 1997 to December 2007, histological samples and clinical data of 1,171 consecutive patients operated for DIN in a single institution were collected. The study was performed in accordance with the REMARK criteria. The independent prognostic role of Ki-67 LI was evaluated with a multivariable Cox regression model. A restricted cubic splines model was used to evaluate the prognostic role of Ki-67 LI as a continuous variable.

Results: Overall, median age was 52 years (range 23–88), median Ki-67 LI 15% (range 1–80) and median follow-up 86 months (range 1–192). Overall, 549 (46.9%) women were premenopausal at the time of diagnosis. A total of 872 (74.5%) patients underwent breast conservative surgery (BCS). Whole breast radiotherapy (RT) was administered to 356 patients, and 506 patients received low dose tamoxifen (HT) (20mg/week or 5 mg/day). Histologically, most of the cases had a prevalent solid or cribriform pattern (75%), were DIN1c and DIN2 (80%), ER+ (80%), and showed a high (≥14%) Ki-67 LI (54%). The prevalence of the immunohistochemically defined subtypes was 39.5% for Luminal (Lum) A, 22.8% for LumB/Her-2−, 18.2% for LumB/Her2+, 15.8% for Her-2+, and 3.7% for Triple Negative. Overall, the rate of invasive and in situ recurrences (5-year cumulative incidence) was 10.7%. Firstly, we analyzed the role of RT according to Ki-67 LI as a continuous variable in DIN2/DIN3 patients after BCS. The curve and interaction model was adjusted for menopause, BMI, Her-2 and ER status, histological grade, presence of necrosis and microcalcifications, and HT. RT was protective in subjects with DIN with Ki-67 LI ≥14%, while no evidence of effect was seen for Ki-67 LI &lt;14%. Notably, the higher the Ki-67 LI, the stronger the effect of RT (P-value for the interaction between RT and Ki-67 LI &lt;0.01). Accordingly, RT was effective in all DIN subtypes with the exception of LumA. The adjusted HRRT vs No RT for LumB/Her2−, LumB/Her2+, and Her2 subtypes was 0.20 (95 % CI, 0.08–0.48), 0.44 (95 % CI, 0.16–1.20), and 0.15 (95 % CI, 0.04–0.50), respectively. The HRRT vs No RT for Triple Negative subtype was 0.40 (95 % CI, 0.07–2.41) and was not adjusted because of the sparse number of events. Finally, we focused the analysis on DIN2 patients stratified by Ki-67 LI. Again, after adjustment for menopause, surgical margins, presence of necrosis, microcalcifications, and HT, RT was not effective in DIN2 patients with Ki-67 LI &lt;14% [HRRT vs No RT: 1.15 (95 % CI 0.47–2.80)]. On the contrary, DIN2 patients with a Ki-67 LI ≥14% mostly benefit of RT in terms of ipsilateral recurrence[HRRT vs No RT: 0.18 (95% CI 0.07–0.46)]. Low dose tamoxifen was effective in either LumA [adjusted HRHT vs No HT: 0.56 (95 % CI 0.33–0.97)] and LumB/HER2− DIN [HRHT vs No HT: 0.51 (95 % CI 0.27–0.95)], but not in LumB/Her2+ [HRHT vs No HT: 1.06 (95 % CI 0.56–2.05).

Conclusion: Our data suggest that Ki-67 LI may be a useful prognostic and predictive adjunct in DIN patients.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD04-07.

Abstract PD03-01: EFFECT OF METFORMIN ON APOPTOSIS IN A PRESURGICAL TRIAL IN NON-DIABETIC PATIENTS WITH BREAST CANCER

BACKGROUND: metformin has been associated with antitumor activity in epidemiological and clinical studies. This effect has been related to different mechanisms of actions, including a reduction of the proliferative activity and an increase of apoptosis. We have recently shown that a 4 week pre-surgical treatment with metformin did not affect Ki-67 LI overall but reduced tumor proliferation Ki67 LI in breast cancer (BC) patients with insulin resistance (IR) (HOMA, fasting blood glucose (mmol/L)*insulin (mU/L)/22.5&gt;2.8) or BMI&gt;27 (Bonanni et al. JCO epub May 7, 2012). The objective of the current analysis was to determine whether metformin induced a modulation of apoptosis (TUNEL) overall and by HOMA index.

TRIAL DESIGN: After tumor biopsy we randomly allocated 200 non-diabetic women with operable breast cancer to either metformin (850 mg/bid) or placebo for 4 weeks prior to surgery. The primary outcome measure was the difference between arms in Ki-67 after 4 weeks of treatment. Here we analyzed the apoptotic cell nuclei in 88 consecutive core biopsies and their paired surgical samples from the initial 100 randomized subjects.

RESULTS: Median TUNEL levels at surgery (Metformin = 10%, IQR, 4–20, Placebo = 8%, IQR, 3–15) were significantly higher as compared with baseline (Metformin = 4%, IQR, 2–7, Placebo = 3%, IQR, 2–6, p &lt; 0.0001), but no difference between arms was noted (p = 0.2, adjusted for age, BMI, TUNEL and Ki67 at baseline). Interestingly, Ki67 and TUNEL levels were highly and positively correlated both at baseline and at surgery (Spearman r=0.51, p &lt; 0.0001). Furthermore, we found a trend to a different metformin effect by the HOMA index (p = 0.1). In the 59 women with HOMA &lt;2.8 there was a higher level of TUNEL at surgery on metformin versus placebo (p = 0.05), while an opposite trend was found in the 28 women with HOMA&gt;2.8 (p = 0.6).

CONCLUSIONS: The levels of TUNEL are significantly higher in the surgical specimens compared with baseline biopsy and are directly correlated with those of Ki-67 (TUNEL is high when Ki-67 is high). We found no significant modulation of TUNEL by metformin but a trend to a different effect according to the IR state, with a similar pattern to Ki-67: decrease by metformin in IR women and increase in non-IR women. Our findings confirm the notion that metformin has dual effects on breast cancer according to IR state. As expected, cancer apoptosis and proliferation are directly related. Our results strengthen the importance of placebo control arms in biomarker trials.

ACKNOWLEDGEMENTS: 2 Grants by AIRC and Italian Ministry of Health.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD03-01.

Abstract P5-11-14: Distribution of Tamoxifen and Five Metabolites into Normal and Malignant Human Breast Cancer Tissue during Conventional and Low Dose Treatment

Background: Biotransformation of tamoxifen leads to metabolites with different pharmacological and toxicological effects. Profiling and screening for active metabolites are important to assess their contribution to the overall therapeutic and adverse effects. The anticancer effect of tamoxifen is believed to be due to the hydroxylated metabolites 4hydroxytamoxifen (4OHtam) and 4hydroxyNdesmethyltamoxifen (4OHNDtam, endoxifen). Its demethylated metabolites have been related to side effects of the drug, whereas effects of tamoxifenNoxide (tamNoxide) have not been evaluated. In the present study we wanted to examine the distribution of tam and five of its metabolites in serum and normal and malignant breast tissues during normal dose (20 mg/day) and low dose (5 or 1 mg/day) regimens after 28 days of continuous dosing.

Methods: Serum and biopsies from 56 patients were available for analysis. The concentrations of tamoxifen and the metabolites 4OHtam, 4OHNDtam, Ndesmethyltamoxifen (NDtam), Ndesdimethyltamoxifen (NDDtam), and tamNoxide in serum and tissues were measured by means of a recently developed highly sensitive liquid chromatography tandem mass spectrometry (LCMSMS) method.

Results: Serum and biopsies from 56 patients were available for analysis. All compounds including the potent metabolites 4OHtam and 4OHNDtam were detected and measured in all samples. The tissue levels of tam and its hydroxylated and demethylated metabolites were highly related to the serum levels (p &lt; 0.000 — 0.0069). The tumor tissue to serum concentration ratios of tamNoxide decreased by increasing doses (p &lt; 0.0001) whereas this ratio was unchanged over the dose range 1-20 mg/day for the other compounds measured.

Conclusion: Tamoxifen and its metabolites were detected in all samples examined including those sampled during the low dose regimens. The tissue levels of tamoxifen and its hydroxylated and demethylated metabolites were strongly corresponding to the serum concentrations, in contrast to those of tamNoxide. The strong relations between the concentrations of the potent active 4OHtam and 4OHNDtam (endoxifen) in serum and target tissues suggest that implementation of therapeutic drug monitoring may represent a tool to improve tamoxifen therapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-11-14.

Abstract PD03-02: A Randomized Pre-Surgical Trial of Metformin in Breast Cancer. Preliminary Feasibility and Safety Results

Background: Metformin has been associated with decreased breast cancer (BC) incidence in diabetic patients in epidemiological studies. Moreover, this drug results in initiation of an AMPK-dependent energy stress response which can adversely affect survival of breast cancer cell lines and inhibition of PI3K/Akt/mTOR signaling leading to reduced proliferation of BC cell lines.

Methods: We conducted a randomized, pre-surgical, phase IIb, placebo-controlled, biomarker trial in women with stage I-III BC candidate to elective surgery. The primary endpoint was the change in cell proliferation in malignant, dysplastic and hyperplastic tissue as measured by Ki-67 labeling index (LI). With 150 subjects, the study was 80% powered to test for the interaction between metformin activity and ER status. Two interim analyses are being planned after 100 and 200 women enrolled. Results: As of June 18, 2010, 175 subjects have been randomized and 162 have completed treatment. Here we report data on the first 100 women enrolled. At the symposium, full data on the first 200 women enrolled will be available. As of December 31, 2009, a total of 163 women were screened, 26 were not eligible and 40 refused to participate, 6 dropped out during the study for AEs (n=2) or refusal to continue treatment (n=4), thus leaving 95 subjects assessable for the primary endpoint. The main subject and tumor characteristics blinded as to the allocated arm were mean age 52 (31-77), Pre/postmenopause, 54/41, mean BMI, 23.6 (18.0-40.2). At baseline, median Ki-67LI was 18% (range 4%-65%) at biopsy and 19% (4%-70%) after 4 weeks at surgery. All adverse events except for 1 SAE were grade 1 or 2, consisting of G2 nausea and G2 diarrhea in 4% and 6% of the cases, respectively. The prevalence of ductal intraepithelial neoplasia was 91% (median Ki-67 LI, 10%) in samples both adjacent and distant from the tumor, whereas the prevalence of ductal hyperplasia was 77% (median Ki-67LI, 2%) in samples distant from the tumor. Conclusions: Our preliminary results show the feasibility, high compliance and safety of a metformin trial in breast cancer patients. Assessment of tissue and circulating biomarkers is currently ongoing to characterize the whole spectrum of metformin activity in malignant and dysplastic tissue.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD03-02.

Prognostic significance of Ki-67 labeling index after short-term presurgical tamoxifen in women with ER-positive breast cancer

BACKGROUND

Studies have shown that Ki-67 response after short-term neoadjuvant aromatase inhibitors may predict recurrence in postmenopausal breast cancer, whereas its prognostic effect in premenopausal women is unknown.

PATIENTS AND METHODS

We compared the prognostic and predictive value of baseline and post-treatment Ki-67 in 120 pre- and postmenopausal women with early-stage estrogen receptor-positive breast cancer who participated in a 4-week presurgical trial of tamoxifen.

RESULTS

After 7.2 years of follow-up, women with post-treatment Ki-67 in the second (14%-19%), third (20%-29%) and top (≥30%) quartiles had a recurrence hazard ratio of 2.92 [95% confidence interval (CI) 0.95-8.96], 4.37 (1.56-12.25) and 6.05 (2.07-17.65), respectively, as compared with those in the bottom quartile (<14%) (P-trend = 0.001). The risk of invasive disease recurrence was 2.2% (95% CI 0.9-5.0) per point increase in baseline Ki-67 (P-trend = 0.076) and 5.0% (95% CI 2.3-7.7) per point increase in post-tamoxifen Ki-67 (P-trend < 0.001). The risk of death was 5.5 (95% CI 1.26-23.16) times higher in patients with post-drug Ki-67 ≥20% than in those with Ki-67 <20% (P-trend = 0.006).

CONCLUSIONS

Ki-67 response after short-term neoadjuvant tamoxifen is a good predictor of recurrence-free survival and overall survival, further supporting its use as surrogate biomarker to personalize adjuvant treatment and to screen novel drugs cost-effectively.

Low-Dose Tamoxifen for the Treatment of Breast Ductal Intraepithelial Neoplasia: Results of a Large Observational Study

Background: The cost-benefit ratio of tamoxifen for breast ductal intraepithelial neoplasia (DIN) is unclear. Since low-dose tamoxifen showed a favorable safety profile and modulation of breast cancer biomarkers in phase II trials, we analyzed a large mono-institutional cohort of women with DIN treated with low-dose tamoxifen or no systemic treatment.Material and Methods: A total of 309 patients with ER positive DIN received either tamoxifen 5 mg/day or 20 mg/week, as part of clinical trials or institutional guidelines and were compared with 371 patients who received no systemic treatment after surgery with or without radiotherapy due to personal preference, allocation to placebo or contraindication to tamoxifen.Results: The 5-year cumulative incidence of recurrence was 14.5% (95% CI, 11.9-17.5), with a negative trend according to age. Women with ER/PgR &gt;50% DIN who were untreated had a higher incidence of breast events than women on tamoxifen (HR 1.76; 95% CI, 1.00-3.12) or women with ER/PgR&lt;50% DIN (HR 1.72; 95% CI, 1.14-2.58). Among untreated patients with ER&gt;50% DIN, recurrence was higher in PgR ≥50% DIN than in PgR &lt;50% DIN, whereas it was similar among low PgR (&lt;50%) DIN against which tamoxifen had no effect. No difference in endometrial cancer incidence was noted.Discussion: High ER and especially high PgR expression is a significant adverse prognostic indicator of DIN against which low-dose tamoxifen appears to be a safe and active treatment. Conversely, women with low expression ER or PgR DIN do not seem to benefit from tamoxifen. A definitive clinical trial is warranted.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2113.

Randomized phase II trial of budesonide versus placebo in high-risk population with screening-detected lung nodules: Update on secondary endpoints

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Background: Lung cancer phase II chemoprevention trials have not focused so far on the peripheral lung. CT discovers small, undetermined peripheral nodules, which may be preinvasive lesions. In a recent phase II trial the glucocorticoid Budesonide reduced peripheral nodules at spiral CT. Methods: We performed a randomized, double-blind, placebo-controlled, phase IIb clinical trial of inhaled budesonide in current (CS) or former smokers (FS) with CT-detected peripheral nodules. Primary endpoint: shrinkage effect on nodules. Secondary endpoints: decrease in size/number of the target lesions, modulation of tumor markers in sputum and plasma, toxicity, effect on pulmonary function. Two hundred and two subjects received 800μg budesonide (B) twice daily or placebo (P) for 1 year. CT scans at 0 and 12 months (mts), and clinical evaluation + serum/plasma collection at 0, 3, 6, and 12 months were performed. Subjects were stratified according to gender, smoking habits (CS vs. FS), and nodule characteristics (solid vs. non-solid). Results: Preliminary data had shown no shrinkage of the nodules in the B treated arm in a per subject analysis (primary objective). We present now results on serum markers (ultrasensitive C-reactive protein, CRP), emphysema and pulmonary function. As compared to baseline, CRP median levels show at 12 months a nonsignificant (p = 0.85) reduction: -0.25 ± 0.63 (B) vs. -1.16 ± 0.97 (P). 12-month values are significantly (p = 0.01) associated with baseline values and smoking status, with higher mean values at 12 months in FS (B 2.1 ± 2.0 vs. P 3.4 ± 1.9). Emphysema values at 12 months are significantly higher (p = 0.0022) in the B (+ 0.29 ± 0.06) versus P arm (+ 0.12 ± 0.07). This difference is not correlated to sex (p = 0.7062) and smoking status (p = 0.8044). As regards spirometry, no significant difference on FEV 1% and DLC/VA appears between arms at 12 months: median FEV 1% values 3.7 ± 1.0 for B versus 2.9 ± 1.0 for P (p = 0.6221); median DLC/VA increase of 0.3 ± 1.9 (B) versus decrease of -3.8 ± 1.6 (P) (p = 0.4191). Conclusions: A significant effect of B on ultrasensitive-CRP and pulmonary function has not been shown. CRP results may indicate the lack of systemic absorption of B. Emphysema appears slightly worse in the B arm, particularly in FS; this is worth further investigation.

No significant financial relationships to disclose.

The effect of transdermal estradiol or oral conjugated oestrogen and fenretinide versus placebo on haemostasis and cardiovascular risk biomarkers in a randomised breast cancer chemoprevention trial

Background:

We have previously reported the favourable effect of transdermal estradiol (E2), relative to oral conjugated equine oestrogen (CEE), on ultrasensitive C-reactive protein after 12 months of treatment in a retinoid-placebo controlled two-by-two randomized breast cancer prevention trial (Decensi A et al (2002) Circulation106 10 1224–8). Here, we investigate the changes in lipids and clotting profile in patients of the same trial.

Methods and results:

Recent post-menopausal women were randomised to either oral CEE 0.625 mg/day and placebo (n = 55), CEE and fenretinide 200 mg/day (n = 56), transdermal E2 50 mg/day and placebo (n = 59) or E2 and fenretinide 200 mg/day (n = 56). Sequential medroxyprogesterone acetate 10 mg/day was given in each group. After 12 months, there was a statistically significant effect of the route of administration of hormone replacement therapy (HRT) on fibrinogen levels; the median percentage change being −5.7% with CEE and −1.1% with E2 (p = 0.012). Total cholesterol decreased in all arms (p < 0.0001). HDL-C decreased significantly with transdermal E2 (p = 0.006) compared to oral CEE and with fenretinide relative to placebo (p<0.001). Triglycerides exhibited an opposite modulation in the HRT route, with a 21.4% median increase with oral CEE and an 8.6% reduction with transdermal E2 (p < 0.0001). Antithrombin-III showed a 4% borderline significant reduction in the fenretinide arm relative to placebo, irrespective of the HRT administration route (p = 0.055).

Conclusions:

Our data indicate that transdermal E2 may be preferable to oral CEE based on its safer cardiovascular risk profile. Fenretinide modified some cardiovascular risk biomarkers and confirmed a safer profile compared to other retinoids.

Correlation of low dose tamoxifen and its metabolites plasma level with Cyp 2D6, and SULT polymorphism; a pharmacogenetics study within a chemoprevention trial

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Background: Tamoxifen (T) is one of the most widely used drug for the treatment and prevention of estrogen receptor (ER) positive breast cancer. Individual genotype can modulate treatment efficacy. T metabolism is catalyzed by multiple enzymes: CYP2D6 is the main mediator for endoxifen, one of the most potent T metabolites. SULT may also play a role in T activation and can modulate hormone levels involved in breast cancer risk. Within a chemoprevention trial, we correlated T and its main metabolite concentration with polymorphisms (SNPs) of CYP2D6 and SULT genes. Methods: Premenopausal women (n 235) were randomly assigned in a double-blind four-arm trial to receive T 5 mg/d, fenretinide 200 mg/d, both agents, or placebo for 2 years CYP2D6 (*4–6) and SULT1A1*3 frequencies were determined using an Allelic Discrimination Assay, following a protocol for real time polymerase chain reaction. In the subjects receiving T, we measured plasma level of the drug, and its metabolites (endoxifen, 4-hydroxy-T, N-desmethyl-T, N-desdimethyl-T and Tnoxide) using a fluorescence detector at 12 and 24 months. Results: SNPs analysis was performed in 118 women; we found 65% wild type (WT), 31% heterozygous (H) and 5% mutated (M) for CYP2D6. The SNP frequency of SULT1A was A1, 61%; SULT1A2 36% and SULT1A3 3%. At one year a positive correlation was observed between CYP2D6 M and plasma level of N- desmethyl-T, the mean plasma level being 54.6, 62.4 and 108.5 ng/ml in WT, H and M, respectively, p=.001 (p=.01 at 24 months). Endoxifen was slightly increased in the WT compared to M (15.4 vs 12.9 ng/ml). SULT polymorphisms did not show any correlation with the drug and metabolite levels. Conclusions: CYP2D6 M mediates an increased level of N- desmethylT. This observation supports the role of CYP2D6 as an important enzyme in T metabolism, but more than one cytochrome P450 isoenzymes is required. to identify good or poor T metabolizers.

No significant financial relationships to disclose.

Effect of tamoxifen at low doses on ultrasensitive C-reactive protein in healthy women

The use of tamoxifen as a breast cancer preventive agent may be contraindicated by an increased risk of endometrial cancer and venous thromboembolic events, particularly in postmenopausal women. Since these estrogenic effects may be dose-related, a dose reduction may reduce toxicity. We have recently shown a comparable activity of lower doses of tamoxifen on putative surrogate biomarkers of cardiovascular disease and breast cancer. To provide further insight into the effect of tamoxifen at low doses on the cardiovascular system, we compared the effect of three different doses on circulating levels of C-reactive protein (CRP), an independent risk marker for cardiovascular disease (CVD), which was lowered by tamoxifen at the standard dose of 20 mg day-1 in previous studies. We compared the changes in CRP after 2 months of either placebo (n = 24), or tamoxifen 10 mg alternate daily (n = 26), or 10 mg day-1 (n = 22), or 20 mg day-1 (n = 19) in healthy women aged 35-70 years. The median percent change was -2.2% (95% CI, -23.3 to 42.8) with placebo, -39.1 (95% CI, -59.9 to -28.7) with 10 mg alternate daily, -56.9% (95% CI, -68.6 to -38.4) with 10 mg day-1 and -42.9% (95% CI, -62.6 to 1.6) with 20 mg day-1 (P = 0.291 for the linear dose-response trend). Similar results were obtained when the data were classified according to blood tamoxifen concentrations, with a median reduction of 47% (95% CI, 65.5-36.3) for women with low tamoxifen concentrations (< 30 ng mL-1). We conclude that tamoxifen at low doses is able to lower ultrasensitive CRP and that this might be associated with a beneficial effect on CVD.

The Italian breast cancer prevention trial with tamoxifen: findings and new perspectives

The Italian Tamoxifen Prevention Study includes 5408 healthy hysterectomized women aged 35-70 years who have been randomized to 20 mg/day of tamoxifen or placebo for 5 years. After 46 months median follow-up, an increased risk of venous vascular events (38 women on tamoxifen vs. 18 women on placebo, P = 0.0053), mainly consisting of superficial phlebitis, has been observed and 41 breast cancers have occurred (19 on tamoxifen vs. 22 on placebo, P = 0.64). However, subgroup analyses indicated a borderline significant reduction of breast cancer among women continuously on estrogen replacement therapy (ERT, mostly transdermal) and receiving tamoxifen, with 8 cases of breast cancer among 390 ERT users on placebo versus 1 case among 362 ERT users on tamoxifen (RR = 0.13, 95% CI = 0.02-1.02). Withdrawal rate (mainly due to menopausal symptoms) differed according to ERT use, with compliance being 78% and 75% at 3 and 5 years, respectively, for women who never took ERT, and 92% and 88% at 3 and 5 years, respectively, for women not on ERT at baseline, but who took ERT at some time during the trial. Pharmacokinetic and pharmacodynamic (surrogate end point biomarkers) studies showed that a lower dose of tamoxifen (such as 5 mg/day) does not affect the drug's activity on several biomarkers of both cardiovascular and breast cancer risk. We are therefore planning a multicenter placebo-controlled phase III trial in postmenopausal healthy women on hormone replacement therapy (HRT) to test whether the combination of HRT and low-dose tamoxifen retains the benefits while reducing the risks of either agent maintaining a high compliance rate.

Effect of raloxifene on IGF-I and IGFBP-3 in postmenopausal women with breast cancer

The effect on the IGF system of 60 mg and 600 mg daily of raloxifene administered for 2 weeks prior to surgery was investigated in 37 postmenopausal women with breast cancer. Raloxifene significantly decreased insulin-like growth factor (IGF-I) as compared to placebo (P < 0.05) with no dose-response relationship. No significant change was observed in IGFBP-3, while the IGF-I/IGFBP-3 molar ratio was decreased by treatment, with a statistically significant effect only for the higher dose. Given that high plasma levels of IGF-I have been suggested as a risk factor for breast cancer, these findings provide further support for the potential activity of raloxifene in breast cancer prevention.

Effect of low dose tamoxifen on the insulin-like growth factor system in healthy women

The use of tamoxifen as a preventive agent may be limited by the increased risk of endometrial cancer and venous thromboembolic events observed in postmenopausal women. We have recently shown a comparable activity of lower doses of tamoxifen on several surrogate biomarkers of cardiovascular disease and breast cancer, including Insulin-like Growth Factor-I (IGF-I). To provide further insight into the effect of tamoxifen at low doses on the IGF system, we have correlated the drug serum levels attained after 2 months of either placebo (n = 32), tamoxifen 20 mg/day (n = 26), 10 mg/day (n = 23) or 10 mg/every other day (n = 29) with the changes in IGF-I, Insulin-like Growth Factor-II (IGF-II), Insulin-like Growth Factor Binding Protein-1 (IGFBP-1), Insulin-like Growth Factor Binding Protein-3 (IGFBP-3), and IGF-I/IGFBP-3 ratio. Compared with placebo, tamoxifen induced a mean +/- standard error (SE) reduction of IGF-I of 16.9 +/- 7.8%, p < 0.05, a non-significant increase of 22.9 +/- 12.2% in IGF-II, an increase in IGFBP-1 of 49.3 +/- 22.7%, p < 0.05, and a non-significant change of IGFBP-3 (-4.0% +/- 9.2). No significant concentration-response relationship was observed between serum tamoxifen concentrations and the biomarker changes except for the ratio of IGF-I/IGFBP-3, which decreased by 1.53 +/- 0.68% for any increase by 10 ng/ml of serum tamoxifen concentration (p = 0.02). Although low tamoxifen concentrations induce a comparable modulation of the IGF family relative to the conventional dose, the lower decrements in the IGF-I/IGFBP-3 ratio observed at low drug concentrations might be associated with a reduced preventive activity. Further studies on the search of the minimal active dose of tamoxifen are warranted.

Correlation between tamoxifen elimination and biomarker recovery in a primary prevention trial

We have shown previously that a reduction from the conventional dose of tamoxifen is associated with a comparable modulation of circulating biomarkers, including insulin-like growth factor-I and cholesterol. In the present study, we have correlated serum tamoxifen elimination with biomarker recovery in healthy subjects completing a 5-year intervention period. Tamoxifen, N-desmethyltamoxifen, and biomarker levels were measured at 0 (baseline), 2, 4, and 6 weeks after completion of treatment in 23 healthy postmenopausal women allocated to tamoxifen 20 mg/day and in 6 women allocated to placebo. Mean (+/-SD) serum tamoxifen and N-desmethyltamoxifen concentrations were, respectively, 141 +/- 50 and 226 +/- 77 ng/ml at baseline, 36 +/- 19 and 99 +/- 46 at 2 weeks, 20 +/- 15 and 61 +/- 37 at 4 weeks, and 12 +/- 9 and 36 +/- 26 at 6 weeks. Serum tamoxifen and N-desmethyltamoxifen half-lives were 9 and 13 days, respectively. Body mass index was associated positively with drug's serum half-life. Compared with baseline values, the percentage increase in total cholesterol, low-density lipoprotein cholesterol, and insulin-like growth factor-I 4 weeks after treatment completion was 5, 9, and 14%, respectively. No change during the 6-week period was observed in the placebo arm. Our findings indicate that the biomarker recovery is slower than serum tamoxifen elimination, suggesting that low tamoxifen concentrations may still exert a biological effect. In addition, the prolonged half-life of tamoxifen and metabolite provides the rationale for a weekly administration of the drug in a preventive context. However, the clinical implications of our findings remain to be defined.

Chemoprevention of breast cancer: the Italian experience

The activity of our group is focused on the conduction of chemoprevention clinical trials of breast cancer in at-risk subjects, among which we include women on hormone replacement therapy (HRT). The role of the insulin-like growth factor (IGF) system and of mammographic breast density as surrogate biomarkers for breast cancer prevention is also being investigated. The IGF system is involved in human carcinogenesis of several solid tumors. IGF-I is a potent mitogen for breast cancer cells; elevated circulating IGF-I levels have been associated with a higher risk of premenopausal breast cancer, prostate and colorectal cancer in prospective studies. Both tamoxifen and the synthetic retinoid fenretinide (4-HPR) have been shown to decrease plasma IGF-I levels. A trial of their combination is ongoing in premenopausal women with increased risk for breast cancer. Mammographic breast density has also been associated with an increased risk of breast cancer in several prospective studies. In this article, we discuss the rationale for selection of appropriate cohorts, candidate agents, and putative surrogate biomarkers in our breast cancer prevention trials. Moreover, updated results of the secondary prevention trial of 4-H PR and of the primary prevention trial of tamoxifen are presented. Finally, the rationale for a reduction of tamoxifen dose in future prevention trials is provided.

Effect of blood tamoxifen concentrations on surrogate biomarkers in a trial of dose reduction in healthy women

PURPOSE

Tamoxifen administered at 20 mg/d has been shown to decrease breast cancer incidence in at-risk women by 50%, but toxicity may limit its broad use, particularly in postmenopausal women. Because toxicity may be dose-dependent, we studied the biologic activity of low concentrations of tamoxifen to determine the plausibility of a dose reduction.

PATIENTS AND METHODS

We measured the blood concentrations of tamoxifen and its main metabolites in a dose titration study in 105 healthy women (placebo, tamoxifen 10 mg on alternate days, tamoxifen 10 mg/d, and tamoxifen 20 mg/d). Drug levels measured after 2 months of treatment were correlated with the changes in surrogate biomarkers of different diseases, including lipid profile, blood cell count, fibrinogen, antithrombin III, osteocalcin, and insulin-like growth factor I, a promising surrogate biomarker of breast cancer.

RESULTS

The means (+/- SD) for tamoxifen and N-desmethyltamoxifen (metabolite X) concentrations (ng/mL) were dose-related, being, respectively, 0 and 0 with placebo, 26.8 +/- 15.1 and 43.7 +/- 22.5 with 10 mg every other day, 51.2 +/- 24.1 and 90.7 +/- 48.0 with 10 mg/d, and 136.0 +/- 52.7 and 230.6 +/- 75.0 with 20 mg/d of tamoxifen. At variance, the biomarker changes were of comparable magnitude at any drug concentration except for platelet count and triglycerides levels, the latter showing a trend to an increase with increasing tamoxifen concentrations.

CONCLUSION

An 80% reduction in blood concentrations does not seem to affect the activity of tamoxifen on biomarkers of cardiovascular or breast cancer risk and may in fact have a more favorable safety profile. Additional studies are warranted to determine the most appropriate dose of this agent.

Effect of tamoxifen on lipoprotein(a) and insulin-like growth factor-I (IGF-I) in healthy women

Studies in breast cancer patients have shown that tamoxifen decreases circulating levels of lipoprotein(a) (Lp(a)), an independent risk factor for premature coronary heart disease, and insulin-like growth factor-I (IGF-I), a promising surrogate biomarker for breast cancer. Since a common hormone regulatory pathway has been suggested for both biomarkers, we measured Lp(a) levels for 6 months in 68 healthy women participating in a chemoprevention trial of tamoxifen and correlated its changes with IGF-I. After 1 month, mean Lp(a) levels decreased by 23% with tamoxifen and increased by 6% with placebo (P = 0.033). No further change was observed after 2 and 6 months. Women with abnormal values at baseline (i.e. > 30 mg/dl) showed the highest reduction. The mean levels of IGF-I decreased by 23.5% with tamoxifen and remained stable with placebo, but the changes induced by tamoxifen in Lp(a) and IGF-I levels were uncorrelated. Our results support the observation that tamoxifen may be a suitable preventive option for women with multiple disease risk factors.

Biologic activity of tamoxifen at low doses in healthy women

BACKGROUND

Results of a clinical trial recently completed in the United States indicate that administration of tamoxifen (20 mg/day) to women at risk can reduce breast cancer incidence by approximately 50% but is associated with an increased risk of developing endometrial cancer and venous thromboembolic events. Since these adverse effects may be dose related, we investigated the effect of tamoxifen on several biomarkers when the drug was given at doses lower than those currently in use.

METHODS

In two sequential experiments, 127 healthy hysterectomized women aged 35-70 years were randomly assigned to one of the following four treatment arms: placebo (n = 31) or tamoxifen at 20 mg/day (n = 30) (first experiment); or tamoxifen at 10 mg/day (n = 34) or tamoxifen at 10 mg/ alternate days (n = 32) (second experiment). Baseline and 2-month measurements of the following parameters were compared: 1) total cholesterol (primary end point) and other surrogate markers of cardiovascular disease, e.g., low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and lipoprotein(a); 2) blood cell count; 3) fibrinogen; 4) antithrombin III; 5) osteocalcin; and, 6) in a subgroup of 103 women, insulin-like growth factor-I (IGF-I), a possible surrogate marker for breast cancer.

RESULTS

After adjustment for the baseline values, there were reductions in circulating levels of total cholesterol and IGF-I of the same magnitude in all three tamoxifen treatment arms. A similar pattern was observed for most of the other parameters. In the placebo arm, fibrinogen level, which showed a decrease, was the only parameter exhibiting change.

CONCLUSIONS

Up to a 75% reduction in the conventional dose of tamoxifen (i.e., 20 mg/day) does not affect the activity of the drug on a large number of biomarkers, most of which are surrogate markers of cardiovascular disease. This study was hypothesis generating, and larger studies are warranted to assess the efficacy of tamoxifen at low doses.