Aliana Guerrieri-Gonzaga

Dual Effect of Metformin on Breast Cancer Proliferation in a Randomized Presurgical Trial

PURPOSE Metformin is associated with reduced breast cancer risk in observational studies in patients with diabetes, but clinical evidence for antitumor activity is unclear. The change in Ki-67 between pretreatment biopsy and post-treatment surgical specimen has prognostic value and may predict antitumor activity in breast cancer. PATIENTS AND METHODS After tumor biopsy, we randomly allocated 200 nondiabetic women with operable breast cancer to either metformin 850 mg/twice per day (n = 100) or placebo (n = 100). The primary outcome measure was the difference between arms in Ki-67 after 4 weeks adjusted for baseline values. RESULTS Overall, the metformin effect on Ki-67 change relative to placebo was not statistically significant, with a mean proportional increase of 4.0% (95% CI, -5.6% to 14.4%) 4 weeks apart. However, there was a different drug effect depending on insulin resistance (homeostasis model assessment [HOMA] index > 2.8, fasting glucose [mmol/L] × insulin [mU/L]/22.5; P(interaction) = .045), with a nonsignificant mean proportional decrease in Ki-67 of 10.5% (95% CI, -26.1% to 8.4%) in women with HOMA more than 2.8 and a nonsignificant increase of 11.1% (95% CI, -0.6% to 24.2%) with HOMA less than or equal to 2.8. A different effect of metformin according to HOMA index was noted also in luminal B tumors (P(interaction) = .05). Similar trends to drug effect modifications were observed according to body mass index (P = .143), waist/hip girth-ratio (P = .058), moderate alcohol consumption (P = .005), and C-reactive protein (P = .080). CONCLUSION Metformin before surgery did not significantly affect Ki-67 overall, but showed significantly different effects according to insulin resistance, particularly in luminal B tumors. Our findings warrant further studies of metformin in breast cancer with careful consideration to the metabolic characteristics of the study population.

Tamoxifen and metabolite concentrations in serum and breast cancer tissue during three dose regimens in a randomized preoperative trial.

Purpose: Both therapeutic and adverse effects of tamoxifen may be related to its tissue concentrations. We investigated concentrations of tamoxifen, 4-hydroxytamoxifen, N-desmethyltamoxifen, and N-didesmethyltamoxifen in serum, normal breast, and breast cancer tissues during conventional dosage and two low-dose regimens. Furthermore we studied tamoxifen effects on the cancer proliferation marker Ki-67, and on sex hormone-binding globulin (SHBG). Experimental Design: From September 1999 to August 2001, 120 breast cancer patients were randomized to 20-, 5-, or 1-mg tamoxifen daily. We measured serum and tissue concentrations of tamoxifen and three metabolites after 28 days of treatment, and the changes between baseline and post-treatment levels of SHBG and Ki-67. Results: The median (range) tamoxifen concentrations (ng/ml) at doses of 1, 5, and 20 mg daily (n = 38, 37, and 36) were 7.5 (2.9–120.9), 25.2 (1.9–180.9), and 83.6 (8.7–134.4) in serum, and 78.2 (35.9–184), 272.3 (122–641), and 744.4 (208.6–2556) in breast cancer tissue, respectively. Tamoxifen levels followed a dose-concentration relationship. The concentrations of tamoxifen and metabolites were related to each other. Serum and tissue concentrations of tamoxifen were associated with corresponding changes of SHBG levels, whereas changes of Ki-67 levels were not related. Conclusions: Estrogen agonistic effects of tamoxifen on SHBG decreased with lower dosage, whereas tamoxifen effects on Ki-67 expression did not change. This together with a >10-fold variation in serum tamoxifen concentrations and a serum to tissue concentration relationship suggest that tamoxifen treatment may be improved by administration of lower doses and therapeutic drug monitoring.

Effect of Transdermal Estradiol and Oral Conjugated Estrogen on C-Reactive Protein in Retinoid-Placebo Trial in Healthy Women

Background—The increase in C-reactive protein (CRP) during oral conjugated equine estrogen (CEE) may explain the initial excess of cardiovascular disease observed in clinical studies. Because the effect of transdermal estradiol (E2) on CRP is unclear, we compared CRP changes after 6 and 12 months of transdermal E2 and oral CEE in a randomized 2×2 retinoid-placebo trial. Methods and Results—A total of 189 postmenopausal women were randomized to 50 &mgr;g/d transdermal E2 and 100 mg BID of the retinoid fenretinide (n=45), 50 &mgr;g/d transdermal E2 and placebo (n=49), 0.625 mg/d oral CEE and 100 mg BID fenretinide (n=46), or 0.625 mg/d oral CEE and placebo (n=49) for 1 year. Sequential medroxyprogesterone acetate was added in each group. Relative to baseline, CRP increased by 10% (95% CI −9% to 33%) and by 48% (95% CI 22% to 78%) after 6 months of transdermal E2 and oral CEE, respectively. The corresponding figures at 12 months were 3% (95% CI −14% to 23%) for transdermal E2 and 64% (95% CI 38% to 96%) for oral CEE. Fenretinide did not change CRP levels at 6 and 12 months relative to placebo. Relative to oral CEE, the mean change in CRP after 12 months of transdermal E2 was −48% (95% CI −85% to −7%, P =0.012), whereas fenretinide was associated with a mean change of −1% (95% CI −34% to 40%, P =0.79) compared with placebo. Conclusions—In contrast to oral CEE, transdermal E2 does not elevate CRP levels up to 12 months of treatment. The implications for early risk of coronary heart disease require further studies.

Is it Time to Test Metformin in Breast Cancer Clinical Trials

Several studies have identified an increased risk of cancer in type 2 diabetic patients and this is in accordance with the hypothesis that increased insulin levels might promote cancer. Thus, there is a great interest in exploring the possibility that antidiabetic therapies lowering insulin levels could decrease cancer incidence or cancer-related mortality. Recent observational studies have shown that metformin, an oral safe and well-tolerated insulin-sensitizer antidiabetic drug, has been associated with reduced cancer risk. Recently, several preclinical studies have evaluated the effect of metformin in vivo on nude mice and showed a significant reduction of both breast epithelial cell proliferation and protein synthesis. Further investigations in the clinical setting are well-supported by the promising results obtained thus far. At the European Institute of Oncology, the Division of Cancer Prevention and Genetics is planning to conduct a clinical trial to evaluate the activity of metformin on tumor cell proliferation in breast cancer patients undergoing surgery. It will be a presurgical randomized, double blind, placebo-controlled phase II biomarker trial: 100 histologically confirmed breast cancer patients will be randomly assigned to metformin (850 mg twice/daily) or placebo for 28 + 7 days till surgery to assess drug activity on tumor proliferation, as measured by Ki-67. The confirmation of the efficacy of metformin on cancer cell proliferation may lead the way to larger chemoprevention clinical trials. (Cancer Epidemiol Biomarkers Prev 2009;18(3):701–5)

Randomized double-blind 2 x 2 trial of low-dose tamoxifen and fenretinide for breast cancer prevention in high-risk premenopausal women.

PURPOSE Tamoxifen and fenretinide are active in reducing premenopausal breast cancer risk and work synergistically in preclinical models. The authors assessed their combination in a two-by-two biomarker trial. PATIENTS AND METHODS A total of 235 premenopausal women with pT1mic/pT1a breast cancer (n = 21), or intraepithelial neoplasia (IEN, n = 160), or 5-year Gail risk > or = 1.3% (n = 54) were randomly allocated to either tamoxifen 5 mg/d, fenretinide 200 mg/d, their combination, or placebo. We report data for plasma insulin-like growth factor I (IGF-I), mammographic density, uterine effects, and breast neoplastic events after 5.5 years. RESULTS During the 2-year intervention, tamoxifen significantly lowered IGF-I and mammographic density by 12% and 20%, respectively, fenretinide by 4% and 10% (not significantly), their combination by 20% and 22%, with no evidence for a synergistic interaction. Tamoxifen increased endometrial thickness principally in women becoming postmenopausal, whereas fenretinide decreased endometrial thickness significantly. The annual rate of breast neoplasms (n = 48) was 3.5% +/- 1.0%, 2.1% +/- 0.8%, 4.7% +/- 1.3%, and 5.2% +/- 1.3% in the tamoxifen, fenretinide, combination, and placebo arms, respectively, with hazard ratios (HRs) of 0.70 (95% CI, 0.32 to 1.52), 0.38 (95% CI, 0.15 to 0.90), and 0.96 (95% CI, 0.46 to 1.99) relative to placebo (tamoxifen x fenretinide adverse interaction P = .03). There was no clear association with tumor receptor type. Baseline IGF-I and mammographic density did not predict breast neoplastic events, nor did change in mammographic density. CONCLUSION Despite favorable effects on plasma IGF-I levels and mammographic density, the combination of low-dose tamoxifen plus fenretinide did not reduce breast neoplastic events compared to placebo, whereas both single agents, particularly fenretinide, showed numerical reduction in annual odds of breast neoplasms. Further follow-up is indicated.

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.

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.

Efficacy of tamoxifen based on cytochrome P450 2D6, CYP2C19 and SULT1A1 genotype in the Italian Tamoxifen Prevention Trial

The role of pharmacogenomics and tamoxifen was investigated by analyzing several polymorphisms of cytochrome P450 and SULT1A1 gene in a nested case control study from the Italian Tamoxifen Prevention Trial. This study included 182 Caucasian subjects, 47 breast cancer (BC) cases and 135 matched controls. We used the AmpliChip CYP450 Test to screen 33 alleles of CYP2D6 and 3 of CYP2C19. One more variant for CYP2C19*17 and two single-nucleotide polymorphisms for the gene SULT1A1 were also performed. By using the AmpliChip CYP450 Test, out of 182 subjects, we identified 8 poor metabolizer (PM), 17 intermediate metabolizer (IM), 151 extensive metabolizer (EM) and 3 ultrarapid metabolizer (UM). PM women allocated to the tamoxifen arm showed a higher risk of developing BC compared to the remaining phenotypes (P=0.035). In an exploratory analysis, among 58 women with a CYP2D6*2A allele, 9 BCs were diagnosed in the placebo arm and only 1 in the tamoxifen arm (P=0.0001). CYP2C19 and SULT1A1 polymorphisms did not show any correlation with tamoxifen efficacy. Tamoxifen showed reduced efficacy in CYP2D6 PMs in the chemoprevention setting. Conversely, the CYP2D6*2A allele may be associated with increased efficacy of tamoxifen. These findings support the relevance of pharmaco-genomics in tailoring tamoxifen treatment.

Randomized Dose-Ranging Trial of Tamoxifen at Low Doses in Hormone Replacement Therapy Users

PURPOSE The combination of hormone replacement therapy (HRT) and low-dose tamoxifen may retain the benefits while reducing the risks of either agent. We assessed the optimal biologic dose and schedule of tamoxifen in HRT users using surrogate end point biomarkers and menopausal symptoms. SUBJECTS AND METHODS Two hundred ten current or de novo HRT users were randomly assigned to one of the following four arms: tamoxifen 1 mg/day and placebo/week, placebo/day and tamoxifen 10 mg/week, tamoxifen 5 mg/day and placebo/week, or both placebos for 12 months. The primary end point was the change of plasma insulinlike growth factor 1 (IGF-I) through 12 months, and secondary end points were IGF-I/IGF binding protein-3 (IGFBP-3) ratio, fibrinogen, antithrombin III, C reactive protein, C-telopeptide, mammographic percent density, and endometrial thickness. Endometrial proliferation was assessed by Pipelle biopsy in superficial, deep glandular, and stromal compartments after 12 months. RESULTS Compared with placebo, IGF-I declined in all tamoxifen arms (P = .005), with a greater change on 5 mg/day (P = .019 v 10 mg/week or 1 mg/day). Tamoxifen increased IGFBP-3 and lowered antithrombin-III, C reactive protein, and mammographic density, with greater effects of 5 mg/day. Tamoxifen increased endometrial thickness but not Ki-67 expression, which was lower on 5 mg/day among the three doses. Menopausal symptoms were not significantly worsened by tamoxifen. CONCLUSION Doses of tamoxifen < or = 5 mg/day modulate favorably biomarkers of breast carcinogenesis and cardiovascular risk in HRT users with no increase of endometrial proliferation and menopausal symptoms. A dose of 5 mg/day was the most effective and has been selected for a phase III trial in HRT users.

The effect of metformin on apoptosis in a breast cancer presurgical trial.

Background:Metformin has been associated with antitumour activity in breast cancer (BC) but its mechanism remains unclear. We determined whether metformin induced a modulation of apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) overall and by insulin resistance status in a presurgical trial.Methods:Apoptosis was analysed in core biopsies and in surgical samples from 100 non-diabetic BC patients participating in a randomised trial of metformin vs placebo given for 4 weeks before surgery.Results:Eighty-seven subjects (45 on metformin and 42 on placebo) were assessable for TUNEL measurement at both time points. TUNEL levels at surgery were higher than that at baseline core biopsy (P<0.0001), although no difference between arms was noted (metformin arm: median difference surgery-biopsy levels +4%, interquartile range (IQR): 2–12; placebo arm: +2%, IQR: 0–8, P=0.2). Ki67 labelling index and TUNEL levels were directly correlated both at baseline and surgery (Spearman’s r=0.51, P<0.0001). In the 59 women without insulin resistance (HOMA index<2.8) ,there was a higher level of TUNEL at surgery on metformin vs placebo (median difference on metformin +4%, IQR: 2–14 vs +2%, IQR: 0–7 on placebo), whereas an opposite trend was found in the 28 women with insulin resistance (median difference on metformin +2%, IQR: 0–6, vs +5%, IQR: 0–15 on placebo, P-interaction=0.1).Conclusion:Overall, we found no significant modulation of apoptosis by metformin, although there was a trend to a different effect according to insulin resistance status, with a pattern resembling Ki67 changes. Apoptosis was significantly higher in the surgical specimens compared with baseline biopsy and was directly correlated with Ki67. Our findings provide additional evidence for a dual effect of metformin on BC growth according to insulin resistance status.