Extended adjuvant tamoxifen for breast cancer--a new era?

High-affinity tamoxifen analogues retain extensive positional disorder when bound to calmodulin

Using a combination of NMR and fluorescence measurements, we have investigated the structure and dynamics of the complexes formed between calcium-loaded calmodulin (CaM) and the potent breast cancer inhibitor idoxifene, a derivative of tamoxifen. High-affinity binding (K d ∼ 300  nM) saturates with a 2 : 1 idoxifene : CaM complex. The complex is an ensemble where each idoxifene molecule is predominantly in the vicinity of one of the two hydrophobic patches of CaM but, in contrast with the lower-affinity antagonists TFP, J-8, and W-7, does not substantially occupy the hydrophobic pocket. At least four idoxifene orientations per domain of CaM are necessary to satisfy the intermolecular nuclear Overhauser effect (NOE) restraints, and this requires that the idoxifene molecules switch rapidly between positions. The CaM molecule is predominantly in the form where the N and C-terminal domains are in close proximity, allowing for the idoxifene molecules to contact both domains simultaneously. Hence, the 2 : 1 idoxifene : CaM complex illustrates how high-affinity binding occurs without the loss of extensive positional dynamics.

Bisphosphonates and breast cancer survival: a meta-analysis and trial sequential analysis of 81508 participants from 23 prospective epidemiological studies

BACKGROUND

We assessed the effect of bisphosphonates (BPs) on breast cancer (BCa) patient survival and explored how long the effect can persist after treatment.

METHODS

We performed a meta-analysis and trial sequential analysis (TSA) of prospective studies including randomized controlled trials (RCTs) and cohort studies. We performed extensive sensitivity analyses to assess the robustness of the findings.

RESULTS

Seventeen RCTs and eight cohorts with 81508 BCa patients were identified. A significant beneficial effect of BPs on BCa survival was found (RR, 0.725; 95% CI, 0.627-0.839), and the TSA results also suggested firm evidence for this beneficial effect. Both summarized results from RCTs and cohorts provided firm evidence for this effect, although the effect estimates were stronger from cohorts than RCTs (RR, 0.892; 95% CI, 0.829-0.961; 0.570; 95% CI, 0.436-0.745; respectively). This beneficial effect was confirmed for bone-metastases (RR, 0.713; 95% CI, 0.602-0.843) and postmenopausal women (RR, 0.737; 95% CI, 0.640-0.850). Importantly, our results demonstrated that this beneficial effect was retained at least 1-2 years after treatment completion (RR, 0.780; 95% CI, 0.638-0.954) and could persist for up to more than 4 years after treatment completion (RR, 0.906; 95% CI, 0.832-0.987). Extensive sensitivity analyses showed the robustness of our results. The GRADE quality of evidence was generally judged to be moderate to high.

CONCLUSIONS

The present study provides firm evidence for a significant beneficial effect of BPs on BCa survival in patients with early-stage BCa, and this effect was retained at least 1-2 years after BP treatment completion.

Bisphosphonates and primary breast cancer risk: an updated systematic review and meta-analysis involving 963,995 women

Importance

Prevention of primary breast cancer (BCa) in women is of great public health importance. The existing results from observational epidemiologic studies focused on the association between bisphosphonates and primary BCa risk have been inconsistent.

Objective

To update this systematic review and meta-analysis to assess the effect of bisphosphonates on primary BCa risk.

Data sources

We comprehensively searched MEDLINE, EMBASE, Cochrane libraries, ProQuest, and Web of Science through June 25, 2018 for relevant studies.

Study selection

Epidemiological studies that assessed the effect of bisphosphonates on the risk of primary BCa in women.

Data extraction and synthesis

We reported this meta-analysis according to the PRISMA guidelines. Available multivariable-adjusted effect estimates and corresponding 95% CIs were pooled with a random-effects model.

Main outcomes and measures

The prespecified main outcome was the risk of primary BCa.

Results

In total, five cohort studies involving 657,558 women and 12,991 primary BCa patients, three population-based case-control studies involving 54,701 primary BCa cases and 237,962 healthy controls and two randomized controlled trials (RCTs) involving 13,774 women and 165 primary BCa patients were included in this meta-analysis. Bisphosphonates were associated with a 12% decreased risk of primary BCa (RR, 0.88; 95% CI, 0.83–0.94). However, when we analyzed study designs separately, the pooled results from observational studies were inconsistent with that from RCTs. The observed association of primary BCa risk with long-term use (≥1 year) of bisphosphonates seemed to be more robust and stronger than that of short-term use (<1 year) (RR, 0.75; 95% CI, 0.66–0.84; and 0.90; 95% CI, 0.84–0.97; respectively).

Conclusion

This meta-analysis adds to the body of evidence for an association between bisphosphonates and a significantly decreased risk of primary BCa. However, future large-scale RCTs are required to validate this concern.

Tamoxifen Pharmacovigilance: Implications for Safe Use in the Future

OBJECTIVE

To survey the status of current tamoxifen pharmacovigilance documentation reflecting tamoxifen use in an academic outpatient multispecialty practice in older adults. This data will help provide information to develop improved pharmacovigilance for a growing cohort of older adult users. The data will be utilized by an interdisciplinary team developing new methods of identifying factors for individualized pharmacovigilance in older adults.

DESIGN

Retrospective chart review to gather descriptive and quantitative data on tamoxifen pharmacovigilance.

SETTING

Multi-specialty clinic.

PATIENTS

Ninety-three patients 60 years of age and older.

MAIN OUTCOME MEASURES

Quantitative report of tamoxifen monitoring as well as descriptive analysis of individual cases.

RESULTS

We found 19 cases of serious adverse events possibly related to tamoxifen (thrombi, uterine malignancies). There were 15 cases with no documentation of pharmacovigilance. All cases had incomplete pharmacovigilance documented. There were two cases of hypercalcemia. There was one case of tamoxifen discontinuation resulting from muscle pain and with chronic muscle pain complaints while receiving tamoxifen. We observed a correlation in older age or high comorbidity burden patients and adverse events patients.

CONCLUSION

Some studies direct the important pharmacovigilance toward prevention of thrombi, uterine malignancies, and hypercalcemia; however, it is not easy to identify recommendations for frequency or focus of monitoring to prevent adverse events for individual older adults based on existing recommendations. The data collected and presented in this study serve to heighten awareness of tamoxifen pharmacovigilance and as a starting point for the application of machine learning techniques and modeling to identify high-risk patients and individualized pharmacovigilance recommendations.

TFF3 is a valuable predictive biomarker of endocrine response in metastatic breast cancer

The stratification of breast cancer patients for endocrine therapies by oestrogen or progesterone receptor expression is effective but imperfect. The present study aims were to validate microarray studies that demonstrate TFF3 regulation by oestrogen and its association with oestrogen receptors in breast cancer, to evaluate TFF3 as a biomarker of endocrine response, and to investigate TFF3 function. Microarray data were validated by quantitative RT-PCR and northern and western transfer analyses. TFF3 was induced by oestrogen, and its induction was inhibited by antioestrogens, tamoxifen, 4-hydroxytamoxifen and fulvestrant in oestrogen-responsive breast cancer cells. The expression of TFF3 mRNA was associated with oestrogen receptor mRNA in breast tumours (Pearson's coefficient=0.762, P=0.000). Monoclonal antibodies raised against the TFF3 protein detected TFF3 by immunohistochemistry in oesophageal submucosal glands, intestinal goblet and neuroendocrine cells, Barrett's metaplasia and intestinal metaplasia. TFF3 protein expression was associated with oestrogen receptor, progesterone receptor and TFF1 expression in malignant breast cells. TFF3 is a specific and sensitive predictive biomarker of response to endocrine therapy, degree of response and duration of response in unstratified metastatic breast cancer patients (P=0.000, P=0.002 and P=0.002 respectively). Multivariate binary logistic regression analysis demonstrated that TFF3 is an independent biomarker of endocrine response and degree of response, and this was confirmed in a validation cohort. TFF3 stimulated migration and invasion of breast cancer cells. In conclusion, TFF3 expression is associated with response to endocrine therapy, and outperforms oestrogen receptor, progesterone receptor and TFF1 as an independent biomarker, possibly because it mediates the malign effects of oestrogen on invasion and metastasis.

Optimal systemic therapy for premenopausal women with hormone receptor-positive breast cancer

Although systemic therapy is one of the cornerstones of therapy for premenopausal women with early stage breast cancer, there remain many unknowns regarding its optimal use. By accident of clinical trial design, much clinical investigation in premenopausal women has focused on chemotherapy. More recently the value of endocrine therapy (tamoxifen and ovarian suppression/ablation via surgery, LHRH agonists, or chemotherapy-induced menopause) has become apparent, and some form of endocrine therapy is viewed as standard for virtually all premenopausal women with early stage invasive breast cancer that expresses estrogen and/or progesterone receptor. Critical open questions include type and duration of endocrine therapy and the development of prognostic/predictive markers to help identify patients who are likely to benefit from chemotherapy in addition to endocrine therapy. For some years, five years of tamoxifen has been viewed as the standard endocrine therapy for premenopausal hormone-responsive breast cancer, although the ATLAS trial suggests that an additional five years of tamoxifen can be considered. The MA17 trial also suggests that an additional five years of an aromatase inhibitor can be considered for women who become postmenopausal during tamoxifen therapy. Information about the value of ovarian suppression continues to emerge, most recently with the demonstration of excellent outcome with goserelin plus tamoxifen in the ABCSG12 trial. The SOFT and TEXT trials, whose accrual is now complete, should help to define optimal endocrine therapy. In addition, use of the 21-gene recurrence score assay may help to delineate the additional value of chemotherapy for patients with node-negative breast cancer, and its utility in the setting of women with 1-3 positive lymph nodes is under study in the RxPONDER trial. Nonetheless, the need for other predictive biomarkers to select appropriate therapy remains real. Finally, attention to long term benefits and side effects of therapy will continue to be vital for these young women.

Tamoxifen improves cholinergically modulated cognitive performance in postmenopausal women

Tamoxifen (TMX) is a selective estrogen receptor modulator that is used as an estrogen receptor antagonist for the treatment and prevention of breast cancer. Whether TMX has antagonist activities in the human brain is less clear and its effects on cognitive function have not been experimentally explored. This study examined how TMX affected cognitive performance in older women using a model of anticholinergic drug-induced cognitive dysfunction. Twenty-one postmenopausal women were administered 20 mg of oral TMX or placebo for 3 months. Participants then took part in five drug challenges using the anticholinergic antinicotinic agent mecamylamine (MECA) and antimuscarinic agent scopolamine (SCOP) and were tested on a comprehensive battery including tasks of attention and psychomotor function, verbal episodic memory, and spatial navigation. After a 3-month placebo washout, participants were then crossed over to the alternate treatment and repeated the drug challenges after 3 months. Compared with placebo treatment, TMX significantly attenuated the impairment from cholinergic blockade on tasks of verbal episodic memory and spatial navigation, but effects on attentional/psychomotor tasks were more variable. Analysis by APOE genotype showed that APO ɛ4+ women showed a greater beneficial effect of TMX on reversing the cholinergic impairment than APO ɛ4- women on most tasks. This study provides evidence that TMX may act as an estrogen-like agonist to enhance cholinergic system activity and hippocampally mediated learning.

Fracture risk in older, long-term survivors of early-stage breast cancer

OBJECTIVES

To examine the effect of breast cancer and its treatment on fracture risk in older breast cancer survivors.

DESIGN

A 10-year prospective cohort study beginning 5 years after a diagnosis of breast cancer for survivors and match date for comparison women.

SETTING

Six integrated healthcare systems.

PARTICIPANTS

Women aged 65 and older (1,286 survivors, 1,286 comparison women, mean age 77.7 in both groups, white, non-Hispanic: survivors, 81.6%; comparison women, 85.2%) who were alive and recurrence free 5 years after a diagnosis of early-stage breast cancer and matched on age, study site, and enrollment year to a comparison cohort without breast cancer.

MEASUREMENTS

Cox proportional hazards models were used to estimate the association between fracture risk and survivor-comparison status, adjusting for drugs and risk factors associated with bone health. A subanalysis was used to evaluate the association between tamoxifen exposure and fracture risk.

RESULTS

No difference was observed in fracture rates between groups (hazard ratio (HR) = 1.1, 95% confidence interval (CI) = 0.9-1.3). The protective effect of tamoxifen was not statistically significant (HR = 0.9, 95% CI = 0.6-1.2).

CONCLUSION

Long-term survivors of early-stage breast cancer diagnosed at age 65 and older are not at greater risk of osteoporotic fractures than age-matched women without breast cancer. There appears to be no long-term protection from fractures with tamoxifen use.