A pilot study to establish a clinical model to perform phase II studies of breast cancer chemopreventive agents in women at high risk with biomarkers as surrogate endpoints for activity

Resolution of Two Sub-Populations of Conformers and Their Individual Dynamics by Time Resolved Ensemble Level FRET Measurements

Most active biopolymers are dynamic structures; thus, ensembles of such molecules should be characterized by distributions of intra- or intermolecular distances and their fast fluctuations. A method of choice to determine intramolecular distances is based on Förster resonance energy transfer (FRET) measurements. Major advances in such measurements were achieved by single molecule FRET measurements. Here, we show that by global analysis of the decay of the emission of both the donor and the acceptor it is also possible to resolve two sub-populations in a mixture of two ensembles of biopolymers by time resolved FRET (trFRET) measurements at the ensemble level. We show that two individual intramolecular distance distributions can be determined and characterized in terms of their individual means, full width at half maximum (FWHM), and two corresponding diffusion coefficients which reflect the rates of fast ns fluctuations within each sub-population. An important advantage of the ensemble level trFRET measurements is the ability to use low molecular weight small-sized probes and to determine nanosecond fluctuations of the distance between the probes. The limits of the possible resolution were first tested by simulation and then by preparation of mixtures of two model peptides. The first labeled polypeptide was a relatively rigid Pro₇ and the second polypeptide was a flexible molecule consisting of (Gly-Ser)₇ repeats. The end to end distance distributions and the diffusion coefficients of each peptide were determined. Global analysis of trFRET measurements of a series of mixtures of polypeptides recovered two end-to-end distance distributions and associated intramolecular diffusion coefficients, which were very close to those determined from each of the pure samples. This study is a proof of concept study demonstrating the power of ensemble level trFRET based methods in resolution of subpopulations in ensembles of flexible macromolecules.

Pilot studies: Are they appropriately reported?

Introduction:

Pilot studies play a pivotal role in deciding whether a main study can be undertaken thereby helping in appropriate framing of time, cost and study methods. However, they cannot be employed for testing a hypothesis and are underpowered in detecting clinically significant differences between the treatment arms. Literature from the west has shown serious lacunae on the part of researchers in reporting pilot studies. The present study assessed the reporting quality of pilot studies published from India.

Materials and Methods:

All the journal articles with a pilot study design published in Indian Journals between January and December 2013 were identified through PubMed search and were assessed for the following: Reason for undertaking the pilot study; report about intention of further work; mention about sample size calculation; statement on other studies evaluating the same hypothesis published elsewhere; whether any hypothesis was tested in the present study; use of inferential statistics including the total number of statistical analyses performed and whether confidence intervals were reported; post-hoc power calculation; application of randomization and/or blinding; total number of study participants and presence of a control group.

Results:

A total of 93 articles were considered in the present study. None of these reported reasons for undertaking the present pilot study and intention to carry of carrying out further work depending on their results. Also, none of them discussed the feasibility of conducting such studies in the given set-up. A total of 69/93 (67.7%) studies tested a hypothesis and had employed at least one of the statistical tests to infer whether any significant difference exist between various groups. None of the 93 articles mentioned confidence intervals and calculation of the sample size despite all mentioning the presence of previous studies evaluating a similar hypothesis. Similarly, none of these studies mentioned post-hoc analysis of power and median (range) of times of statistical analyses performed includes 5 (0–57).

Conclusion:

Pilot studies have been poorly reported in Indian biomedical journals, and more attention is required from all the stakeholders of research; researchers, peer reviewers and journal editors

Effects of a green tea extract, Polyphenon E, on systemic biomarkers of growth factor signalling in women with hormone receptor-negative breast cancer

BACKGROUND

Observational and experimental data support a potential breast cancer chemopreventive effect of green tea.

METHODS

We conducted an ancillary study using archived blood/urine from a phase IB randomised, placebo-controlled dose escalation trial of an oral green tea extract, Polyphenon E (Poly E), in breast cancer patients. Using an adaptive trial design, women with stage I-III breast cancer who completed adjuvant treatment were randomised to Poly E 400 mg (n = 16), 600 mg (n = 11) and 800 mg (n = 3) twice daily or matching placebo (n = 10) for 6 months. Blood and urine collection occurred at baseline, and at 2, 4 and 6 months. Biological endpoints included growth factor [serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF)], lipid (serum cholesterol, triglycerides), oxidative damage and inflammatory biomarkers.

RESULTS

From July 2007-August 2009, 40 women were enrolled and 34 (26 Poly E, eight placebo) were evaluable for biomarker endpoints. At 2 months, the Poly E group (all dose levels combined) compared to placebo had a significant decrease in mean serum HGF levels (-12.7% versus +6.3%, P = 0.04). This trend persisted at 4 and 6 months but was no longer statistically significant. For the Poly E group, serum VEGF decreased by 11.5% at 2 months (P = 0.02) and 13.9% at 4 months (P = 0.05) but did not differ compared to placebo. At 2 months, there was a trend toward a decrease in serum cholesterol with Poly E (P = 0.08). No significant differences were observed for other biomarkers.

CONCLUSIONS

Our findings suggest potential mechanistic actions of tea polyphenols in growth factor signalling, angiogenesis and lipid metabolism.

Classical markers like ER and ki-67, but also survivin and pERK, could be involved in the pathological response to gemcitabine, adriamycin and paclitaxel (GAT) in locally advanced breast cancer patients: results from the GEICAM/2002-01 phase II study

INTRODUCTION

The identification and validation of biomarkers of chemotherapy sensitivity is critical in order to individualise therapy in breast cancer. We evaluated pathological complete response (pCR) to GAT, and its correlation with tumour biomarkers before and after neoadjuvant chemotherapy.

MATERIALS AND METHODS

Stage III (and stage II with T≥5 cm) breast cancer patients were included. Treatment consisted of adriamycin (40 mg/m(2)) day 1, and paclitaxel (150 mg/ m(2)) followed by gemcitabine (2000 mg/m(2)) day 2, every 14 days for six cycles. Tissue from pre-treatment biopsy and surgery was evaluated for biologic markers by immunohistochemistry. Two XPD single nucleotide polymorphisms (SNP) were also analysed.

RESULTS

Forty-six patients entered the trial. Median age was 49.5 years (range 31-72); 25 patients (54%) were pre-menopausal; 12 (26%) were ER-PgR-negative; pCR was observed in 17% (95% CI: 6.4-28.4) of patients. Significant differences in marker expression (mean±SD) in correlation to pathological response were only found in Ki- 67. After treatment, tumours showed lower Ki-67-, surviving- and pERK-positive cells. No correlation between XPD polymorphisms and pCR was found. The overall response rate was 89% (95% CI: 80.1-98.1). Fifteen patients (33%) underwent breast-conserving surgery. The most frequent grade 3 or 4 toxicities were neutropenia (with one febrile neutropenia) and asthenia.

CONCLUSION

These results show an effective regimen with acceptable tolerability. Our data suggest that not only classical markers (ER, Ki-67), but also survivin and pERK could be involved in the response to GAT, which may contribute to therapy individualisation in future study designs.

Surrogate endpoint analysis: an exercise in extrapolation

Surrogate endpoints offer the hope of smaller or shorter cancer trials. It is, however, important to realize they come at the cost of an unverifiable extrapolation that could lead to misleading conclusions. With cancer prevention, the focus is on hypothesis testing in small surrogate endpoint trials before deciding whether to proceed to a large prevention trial. However, it is not generally appreciated that a small surrogate endpoint trial is highly sensitive to a deviation from the key Prentice criterion needed for the hypothesis-testing extrapolation. With cancer treatment, the focus is on estimation using historical trials with both surrogate and true endpoints to predict treatment effect based on the surrogate endpoint in a new trial. Successively leaving out one historical trial and computing the predicted treatment effect in the left-out trial yields a standard error multiplier that summarizes the increased uncertainty in estimation extrapolation. If this increased uncertainty is acceptable, three additional extrapolation issues (biological mechanism, treatment following observation of the surrogate endpoint, and side effects following observation of the surrogate endpoint) need to be considered. In summary, when using surrogate endpoint analyses, an appreciation of the problems of extrapolation is crucial.

Phase IB randomized, double-blinded, placebo-controlled, dose escalation study of polyphenon E in women with hormone receptor-negative breast cancer

Epidemiologic data support an inverse association between green tea intake and breast cancer risk, and numerous experimental studies have shown the antitumor effects of its main component, epigallocatechin gallate (EGCG). We conducted a phase IB dose escalation trial in women with a history of stage I to III hormone receptor-negative breast cancer of an oral green tea extract, polyphenon E (Poly E) 400, 600, 800 twice daily or matching placebo for 6 months. The primary endpoint was to determine the maximum tolerated dose (MTD), defined as the dose that causes 25% dose-limiting toxicity (DLT, grade ≥II). Assignment to dose level was based upon an adaptive design, the continual reassessment method. A mammogram and random core biopsy of the contralateral breast were obtained at baseline and 6 months and serial blood/urine collections every 2 months for biomarker analyses. Forty women were randomized: 10 to placebo, 30 to Poly E (16 at 400 mg, 11 at 600 mg, 3 at 800 mg). There was one DLT at 400 mg (grade III rectal bleeding), three DLTs at 600 mg (grade II weight gain, grade III indigestion and insomnia), and one DLT at 800 mg (grade III liver function abnormality). The DLT rate at 600 mg was 27% (3 of 11). Pharmacologic levels of total urinary tea polyphenols were achieved with all three dose levels of Poly E. Using a novel phase I trial design, we determined the MTD for Poly E to be 600 mg twice daily. This study highlights the importance of assessing toxicity for any chemopreventive agent being developed for chronic use in healthy individuals.

A short-term biomarker modulation study of simvastatin in women at increased risk of a new breast cancer

Observational studies have demonstrated a decreased incidence of cancers among users of HMG CoA reductase inhibitors (statins) and a reduced risk of recurrence among statin users diagnosed with early stage breast cancer. We initiated a prospective study to identify potential biomarkers of simvastatin chemopreventive activity that can be validated in future trials. The contralateral breast of women with a previous history of breast cancer was used as a high-risk model. Eligible women who had completed all planned treatment of a prior stage 0-III breast cancer received simvastatin 40 mg orally daily for 24-28 weeks. At baseline and end-of-study, we measured circulating concentrations of high-sensitivity C-reactive protein (hsCRP), estrogens, and fasting lipids; breast density on contralateral breast mammogram; and quality of life by Rand Short Form 36-Item health survey. Fifty women were enrolled with a median age of 53 years. Total cholesterol, LDL cholesterol, triglyceride, and hsCRP fell significantly during the study (P values < 0.001, <0.001, 0.003, and 0.05, respectively). Estrone sulfate concentrations decreased with simvastatin treatment (P = 0.01 overall), particularly among post-menopausal participants (P = 0.006). We did not observe a significant change in circulating estradiol or estrone concentrations, contralateral mammographic breast density, or reported physical functioning or pain scores. This study demonstrates the feasibility of short-term biomarker modulation studies using the contralateral breast of high-risk women. Simvastatin appears to modulate estrone sulfate concentrations and its potential chemopreventive activity in breast cancer warrants further investigation.

Comparison of Ductal Lavage and Random Periareolar Fine Needle Aspiration as Tissue Acquisition Methods in Early Breast Cancer Prevention Trials

PURPOSE

Short-term phase I and phase II breast cancer prevention trials require tissue acquisition at baseline and after intervention to evaluate modulation of potential biomarkers. Currently used tissue acquisition methods include ductal lavage (DL), random periareolar fine needle aspiration (RPFNA), and core needle biopsy. The optimum method to retrieve adequate samples and the most accepted method by study participants is not known.

EXPERIMENTAL DESIGN

We compared RPFNA and DL as breast tissue acquisition methods for short-term breast cancer prevention trials by evaluating sample adequacy and tolerability in subjects who participated in two prospective phase II breast cancer prevention trials. Eighty-six women at increased risk for breast cancer were included in this study and underwent baseline DL and RPFNA. High risk was defined as having a 5-year Gail score of >1.67% or a history of atypical hyperplasia (AH), lobular carcinoma, or breast cancer.

RESULTS

Median age was 54.5 years (range, 39-75 years); 75% of the women were postmenopausal. About 51% of the women yielded nipple aspiration fluid, and breast fluid samples via DL were retrieved in 73% of these subjects. Of these samples, 71% were adequate samples (greater than 10 epithelial cells). However, when the entire cohort was considered, only 31% of the subjects had adequate samples. RPFNA was also attempted in all subjects, and sample retrieval rate was 100%. Out of these, 96% of the subjects had adequate samples. In DL samples, AH rate was 3.7% was and hyperplasia (H) rate was 11.1%. In RPFNA samples, AH rate was 12.9%, and H rate was 24.7%. Cytology findings in RPFNA samples correlated with age, menopausal status, and breast cancer risk category (previous history of lobular carcinoma in situ). Both procedures were well tolerated, and no complications occurred among participants.

CONCLUSIONS

Considering that the main end point for short-term prevention trials is the modulation of biomarkers, it is important to optimize adequate sample acquisition; therefore, RPFNA is a more practical option for future phase I and II breast cancer prevention trials compared with DL.