Comparison of Circulating Tumor DNA Assays for Molecular Residual Disease Detection in Early-Stage Triple-Negative Breast Cancer.

PURPOSE: Detection of circulating tumor DNA (ctDNA) in patients who have completed treatment for early-stage breast cancer is associated with a high risk of relapse, yet the optimal assay for ctDNA detection is unknown. EXPERIMENTAL DESIGN: The cTRAK-TN clinical trial prospectively used tumor-informed digital PCR (dPCR) assays for ctDNA molecular residual disease (MRD) detection in early-stage triple-negative breast cancer. We compared tumor-informed dPCR assays with tumor-informed personalized multimutation sequencing assays in 141 patients from cTRAK-TN. RESULTS: MRD was first detected by personalized sequencing in 47.9% of patients, 0% first detected by dPCR, and 52.1% with both assays simultaneously (P < 0.001; Fisher exact test). The median lead time from ctDNA detection to relapse was 6.1 months with personalized sequencing and 3.9 months with dPCR (P = 0.004, mixed-effects Cox model). Detection of MRD at the first time point was associated with a shorter time to relapse compared with detection at subsequent time points (median lead time 4.2 vs. 7.1 months; P = 0.02). CONCLUSIONS: Personalized multimutation sequencing assays have potential clinically important improvements in clinical outcome in the early detection of MRD.

A population-scale temporal case-control evaluation of COVID-19 disease phenotype and related outcome rates in patients with cancer in England (UKCCP).

Patients with cancer are at increased risk of hospitalisation and mortality following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the SARS-CoV-2 phenotype evolution in patients with cancer since 2020 has not previously been described. We therefore evaluated SARS-CoV-2 on a UK populationscale from 01/11/2020-31/08/2022, assessing case-outcome rates of hospital assessment(s), intensive care admission and mortality. We observed that the SARS-CoV-2 disease phenotype has become less severe in patients with cancer and the non-cancer population. Case-hospitalisation rates for patients with cancer dropped from 30.58% in early 2021 to 7.45% in 2022 while case-mortality rates decreased from 20.53% to 3.25%. However, the risk of hospitalisation and mortality remains 2.10x and 2.54x higher in patients with cancer, respectively. Overall, the SARS-CoV-2 disease phenotype is less severe in 2022 compared to 2020 but patients with cancer remain at higher risk than the non-cancer population. Patients with cancer must therefore be empowered to live more normal lives, to see loved ones and families, while also being safeguarded with expanded measures to reduce the risk of transmission.

A real-world study of the first use of palbociclib for the treatment of advanced breast cancer within the UK National Health Service as part of the novel Ibrance® Patient Program.

BACKGROUND: The Ibrance® Patient Program was established to provide access to palbociclib for UK National Health Service (NHS) patients with metastatic breast cancer (MBC), pending a funding decision. METHODS: Non-interventional cohort study involving a retrospective medical record review of patients commenced on palbociclib between April and December 2017 at eight UK centres. Primary outcomes included clinicopathological characteristics, treatment patterns, clinical outcomes and selected adverse events. RESULTS: Overall, 191 patients were identified, median age of 57.0 years (range 24.3-90.9); 30% were diagnosed with de novo MBC; 72% received first-line and 10% as ≥ second-line treatment. Median progression-free survival (95% CI) was 22.8 months (16.5-not reached [NR]) in first-line; NR in patients with de novo MBC; 7.8 months (6.8-NR) in ≥ second-line (median follow-up: 24 months). Median overall survival (OS) was NR in the overall cohort; OS rate (95% CI) at 24 months was 74.2% (67.1-81.9%) in first-line; 82.1% (72.6-92.8%) in patients with de novo MBC; 55.0% (37.0-81.8%) in ≥ second-line. Forty-seven per cent of patients developed grade 3-4 neutropenia; 3% febrile neutropenia. CONCLUSION: This study supports the effectiveness of palbociclib and demonstrates the benefit to patients of early access schemes that bridge the gap between regulatory approval and NHS funding for new medicines. CLINICAL TRIAL REGISTRATION: Clinical trial: ClinicalTrial.gov:NCT03921866.

Association of SARS-CoV-2 Spike Protein Antibody Vaccine Response With Infection Severity in Patients With Cancer: A National COVID Cancer Cross-sectional Evaluation.

Importance: Accurate identification of patient groups with the lowest level of protection following COVID-19 vaccination is important to better target resources and interventions for the most vulnerable populations. It is not known whether SARS-CoV-2 antibody testing has clinical utility for high-risk groups, such as people with cancer. Objective: To evaluate whether spike protein antibody vaccine response (COV-S) following COVID-19 vaccination is associated with the risk of SARS-CoV-2 breakthrough infection or hospitalization among patients with cancer. Design, Setting, and Participants: This was a population-based cross-sectional study of patients with cancer from the UK as part of the National COVID Cancer Antibody Survey. Adults with a known or reported cancer diagnosis who had completed their primary SARS-CoV-2 vaccination schedule were included. This analysis ran from September 1, 2021, to March 4, 2022, a period covering the expansion of the UK's third-dose vaccination booster program. Interventions: Anti-SARS-CoV-2 COV-S antibody test (Elecsys; Roche). Main Outcomes and Measures: Odds of SARS-CoV-2 breakthrough infection and COVID-19 hospitalization. Results: The evaluation comprised 4249 antibody test results from 3555 patients with cancer and 294 230 test results from 225 272 individuals in the noncancer population. The overall cohort of 228 827 individuals (patients with cancer and the noncancer population) comprised 298 479 antibody tests. The median age of the cohort was in the age band of 40 and 49 years and included 182 741 test results (61.22%) from women and 115 737 (38.78%) from men. There were 279 721 tests (93.72%) taken by individuals identifying as White or White British. Patients with cancer were more likely to have undetectable anti-S antibody responses than the general population (199 of 4249 test results [4.68%] vs 376 of 294 230 [0.13%]; P < .001). Patients with leukemia or lymphoma had the lowest antibody titers. In the cancer cohort, following multivariable correction, patients who had an undetectable antibody response were at much greater risk for SARS-CoV-2 breakthrough infection (odds ratio [OR], 3.05; 95% CI, 1.96-4.72; P < .001) and SARS-CoV-2-related hospitalization (OR, 6.48; 95% CI, 3.31-12.67; P < .001) than individuals who had a positive antibody response. Conclusions and Relevance: The findings of this cross-sectional study suggest that COV-S antibody testing allows the identification of patients with cancer who have the lowest level of antibody-derived protection from COVID-19. This study supports larger evaluations of SARS-CoV-2 antibody testing. Prevention of SARS-CoV-2 transmission to patients with cancer should be prioritized to minimize impact on cancer treatments and maximize quality of life for individuals with cancer during the ongoing pandemic.

COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study.

PURPOSE: People living with cancer and haematological malignancies are at an increased risk of hospitalisation and death following infection with acute respiratory syndrome coronavirus 2. Coronavirus third dose vaccine boosters are proposed to boost waning immune responses in immunocompromised individuals and increase coronavirus protection; however, their effectiveness has not yet been systematically evaluated. METHODS: This study is a population-scale real-world evaluation of the United Kingdom's third dose vaccine booster programme for cancer patients from 8th December 2020 to 7th December 2021. The cancer cohort comprises individuals from Public Health England's national cancer dataset, excluding individuals less than 18 years. A test-negative case-control design was used to assess the third dose booster vaccine effectiveness. Multivariable logistic regression models were fitted to compare risk in the cancer cohort relative to the general population. RESULTS: The cancer cohort comprised of 2,258,553 tests from 361,098 individuals. Third dose boosters were evaluated by reference to 87,039,743 polymerase chain reaction coronavirus tests. Vaccine effectiveness against breakthrough infections, symptomatic infections, coronavirus hospitalisation and death in cancer patients were 59.1%, 62.8%, 80.5% and 94.5%, respectively. Lower vaccine effectiveness was associated with a cancer diagnosis within 12 months, lymphoma, recent systemic anti-cancer therapy (SACT) or radiotherapy. Patients with lymphoma had low levels of protection from symptomatic disease. In spite of third dose boosters, following multivariable adjustment, individuals with cancer remain at an increased risk of coronavirus hospitalisation and death compared to the population control (OR 3.38, 3.01, respectively. p < 0.001 for both). CONCLUSIONS: Third dose boosters are effective for most individuals with cancer, increasing protection from coronavirus. However, their effectiveness is heterogenous and lower than the general population. Many patients with cancer will remain at the increased risk of coronavirus infections even after 3 doses. In the case of patients with lymphoma, there is a particularly strong disparity of vaccine effectiveness against breakthrough infection and severe disease. Breakthrough infections will disrupt cancer care and treatment with potentially adverse consequences on survival outcomes. The data support the role of vaccine boosters in preventing severe disease, and further pharmacological intervention to prevent transmission and aid viral clearance to limit the disruption of cancer care as the delivery of care continues to evolve during the coronavirus pandemic.

Vaccine effectiveness against COVID-19 breakthrough infections in patients with cancer (UKCCEP): a population-based test-negative case-control study.

BACKGROUND: People with cancer are at increased risk of hospitalisation and death following infection with SARS-CoV-2. Therefore, we aimed to conduct one of the first evaluations of vaccine effectiveness against breakthrough SARS-CoV-2 infections in patients with cancer at a population level. METHODS: In this population-based test-negative case-control study of the UK Coronavirus Cancer Evaluation Project (UKCCEP), we extracted data from the UKCCEP registry on all SARS-CoV-2 PCR test results (from the Second Generation Surveillance System), vaccination records (from the National Immunisation Management Service), patient demographics, and cancer records from England, UK, from Dec 8, 2020, to Oct 15, 2021. Adults (aged ≥18 years) with cancer in the UKCCEP registry were identified via Public Health England's Rapid Cancer Registration Dataset between Jan 1, 2018, and April 30, 2021, and comprised the cancer cohort. We constructed a control population cohort from adults with PCR tests in the UKCCEP registry who were not contained within the Rapid Cancer Registration Dataset. The coprimary endpoints were overall vaccine effectiveness against breakthrough infections after the second dose (positive PCR COVID-19 test) and vaccine effectiveness against breakthrough infections at 3-6 months after the second dose in the cancer cohort and control population. FINDINGS: The cancer cohort comprised 377 194 individuals, of whom 42 882 had breakthrough SARS-CoV-2 infections. The control population consisted of 28 010 955 individuals, of whom 5 748 708 had SARS-CoV-2 breakthrough infections. Overall vaccine effectiveness was 69·8% (95% CI 69·8-69·9) in the control population and 65·5% (65·1-65·9) in the cancer cohort. Vaccine effectiveness at 3-6 months was lower in the cancer cohort (47·0%, 46·3-47·6) than in the control population (61·4%, 61·4-61·5). INTERPRETATION: COVID-19 vaccination is effective for individuals with cancer, conferring varying levels of protection against breakthrough infections. However, vaccine effectiveness is lower in patients with cancer than in the general population. COVID-19 vaccination for patients with cancer should be used in conjunction with non-pharmacological strategies and community-based antiviral treatment programmes to reduce the risk that COVID-19 poses to patients with cancer. FUNDING: University of Oxford, University of Southampton, University of Birmingham, Department of Health and Social Care, and Blood Cancer UK.

Palbociclib in combination with aromatase inhibitors in patients ≥ 75 years with oestrogen receptor-positive, human epidermal growth factor receptor 2 negative advanced breast cancer: A real-world multicentre UK study.

BACKGROUND: Breast cancer incidence increases with age and real-world data is essential to guide prescribing practices in the older population. The aim of this study was to collect large scale real-world data on tolerability and efficacy of palbociclib + AI in the first line treatment of ER+/HER2-advanced breast cancer in those aged ≥75 years. METHODS: 14 cancer centres participated in this national UK retrospective study. Patients aged ≥75 years treated with palbociclib + AI in the first line setting were identified. Data included baseline demographics, disease characteristics, toxicities, dose reductions and delays, treatment response and survival data. Multivariable Cox regression was used to assess independent predictors of PFS, OS and toxicities. RESULTS: 276 patients met the eligibility criteria. The incidence of febrile neutropenia was low (2.2%). The clinical benefit rate was 87%. 50.7% of patients had dose reductions and 59.3% had dose delays. The 12- and 24- month PFS rates were 75.9% and 64.9%, respectively. The 12- and 24- month OS rates were 85.1% and 74.0%, respectively. Multivariable analysis identified PS, Age-adjusted Charlson Comorbidity Index (ACCI) and number of metastatic sites to be independent predictors of PFS. Dose reductions and delays were not associated with adverse survival outcomes. Baseline ACCI was an independent predictor of development and severity of neutropenia. CONCLUSION: Palbociclib is an effective therapy in the real-world older population and is well-tolerated with low levels of clinically significant toxicities. The use of geriatric and frailty assessments can help guide decision making in these patients.

Enhanced axillary assessment using intradermally injected microbubbles and contrast-enhanced ultrasound (CEUS) before neoadjuvant systemic therapy (NACT) identifies axillary disease missed by conventional B-mode ultrasound that may be clinically relevant.

PURPOSE: The purpose of this study is to measure pre-treatment diagnostic yield of malignant lymph nodes (LN) using contrast-enhanced ultrasound (CEUS) in addition to B-mode axillary ultrasound and compare clinicopathological features, response to NACT and long-term outcomes of patients with malignant LN detected with B-mode ultrasound versus CEUS. METHODS: Between August 2009 and October 2016, NACT patients were identified from a prospective database. Follow-up data were collected until May 2019. RESULTS: 288 consecutive NACT patients were identified; 77 were excluded, 110 had malignant LN identified by B-mode ultrasound (Group A) and 101 patients with negative B-mode axillary ultrasound had CEUS with biopsy of sentinel lymph nodes (SLN). In two cases CEUS failed. Malignant SLN were identified in 35/99 (35%) of B-mode ultrasound-negative cases (Group B). Patients in Group A were similar to those in Group B in age, mean diagnostic tumour size, grade and oestrogen receptor status. More Group A patients had a ductal phenotype. In the breast, 34 (31%) Group A patients and 8 (23%) Group B patients achieved a pathological complete response (PCR). In the axilla, 41 (37%) and 13 (37%) Groups A and B patients, respectively, had LN PCR. The systemic relapse rate was not statistically different (5% and 16% for Groups A and B, respectively). CONCLUSIONS: Enhanced assessment with CEUS before NACT identifies patients with axillary metastases missed by conventional B-mode ultrasound. Without CEUS, 22 (63%) of cases in Group B (negative B-mode ultrasound) may have been erroneously classed as progressive disease by surgical SLN excision after NACT.

The impact of Oncotype DX breast cancer assay results on clinical practice: a UK experience.

BACKGROUND: Genomic tests are increasingly being used by clinicians when considering adjuvant chemotherapy for patients with oestrogen receptor-positive (ER+), human epidermal growth factor 2-negative (HER2-) breast cancer. The Oncotype DX breast recurrence score assay was the first test available in the UK National Health Service. This study looked at how UK clinicians were interpreting Recurrence Scores (RS) in everyday practice. METHODS: RS, patient and tumour characteristics and adjuvant therapy details were retrospectively collected for 713 patients from 14 UK cancer centres. Risk by RS-pathology-clinical (RSPC) was calculated and compared to the low/intermediate/risk categories, both as originally defined (RS < 18, 18-30 and > 30) and also using redefined boundaries (RS < 11, 11-25 and > 25). RESULTS: 49.8%, 36.2% and 14% of patients were at low (RS < 18), intermediate (RS 18-30) and high (RS > 30) risk of recurrence, respectively. Overall 26.7% received adjuvant chemotherapy. 49.2% of those were RS > 30; 93.3% of patients were RS > 25. Concordance between RS and RSPC improved when intermediate risk was defined as RS 11-25. CONCLUSIONS: This real-world data demonstrate the value of genomic tests in reducing the use of adjuvant chemotherapy in breast cancer. Incorporating clinical characteristics or RSPC scores gives additional prognostic information which may also aid clinicians' decision making.

Fulvestrant Plus Vistusertib vs Fulvestrant Plus Everolimus vs Fulvestrant Alone for Women With Hormone Receptor-Positive Metastatic Breast Cancer: The MANTA Phase 2 Randomized Clinical Trial.

IMPORTANCE: Randomized clinical trials have demonstrated a substantial benefit of adding everolimus to endocrine therapy. Everolimus inhibits the mammalian target of rapamycin complex 1 (mTORC1) complex but not mTORC2, which can set off an activating feedback loop via mTORC2. Vistusertib, a dual inhibitor of mTORC1 and mTORC2, has demonstrated broad activity in preclinical breast cancer models, showing superior activity to everolimus. OBJECTIVE: To evaluate the safety and efficacy of vistusertib in combination with fulvestrant compared with fulvestrant alone or fulvestrant plus everolimus in postmenopausal women with estrogen receptor-positive advanced or metastatic breast cancer. DESIGN, SETTING, AND PARTICIPANTS: The MANTA trial is an open-label, phase 2 randomized clinical trial in which 333 patients with estrogen receptor-positive breast cancer progressing after prior aromatase inhibitor treatment underwent randomization (2:3:3:2) between April 1, 2014, and October 24, 2016, at 88 sites in 9 countries: 67 patients were assigned to receive fulvestrant, 103 fulvestrant plus vistusertib daily, 98 fulvestrant plus vistusertib intermittently, and 65 fulvestrant plus everolimus. Treatment was continued until disease progression, development of unacceptable toxic effects, or withdrawal of consent. Analysis was performed on an intention-to-treat basis. INTERVENTIONS: Fulvestrant alone or in combination with vistusertib (continuous or intermittent dosing schedules) or everolimus. MAIN OUTCOMES AND MEASURES: The primary end point was progression-free survival (PFS). RESULTS: Among the 333 women in the study (median age, 63 years [range, 56-70 years]), median PFS was 5.4 months (95% CI, 3.5-9.2 months) with fulvestrant, 7.6 months (95% CI, 5.9-9.4 months) with fulvestrant plus daily vistusertib, 8.0 months (95% CI, 5.6-9.9 months) with fulvestrant plus intermittent vistusertib, and 12.3 months (95% CI, 7.7-15.7 months) with fulvestrant plus everolimus. There was no significant difference in PFS between those receiving fulvestrant plus daily or intermittent vistusertib and fulvestrant alone (hazard ratio, 0.88 [95% CI, 0.63-1.24]; P = .46; and hazard ratio, 0.79 [95% CI, 0.55-1.12]; P = .16). CONCLUSIONS AND RELEVANCE: The combination of fulvestrant plus everolimus demonstrated significantly longer PFS compared with fulvestrant plus vistusertib or fulvestrant alone. The trial failed to demonstrate a benefit of adding the dual mTORC1 and mTORC2 inhibitor vistusertib to fulvestrant. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02216786 and EudraCT number: 2013-002403-34.

Bronchoalveolar carcinoma as an unsuspected cause for worsening shortness of breath in a patient with metastatic breast cancer.

A 70-year-old woman with lung metastases from a breast cancer presented with worsening cough and dyspnoea. She recently had a pleurodesis for a malignant pleural effusion. Chest CT scans demonstrated various radiological changes leading to diagnostic challenges. Differential diagnoses included empyema, pleural disease progression, pulmonary oedema, pneumonitis, lymphangitis and atypical infections. She deteriorated despite a multimodality treatment strategy. Postmortem examination confirmed that lung changes were consistent with a bronchoalveolar carcinoma unrelated to the known metastatic breast cancer. The eventual knowledge of this diagnosis was reassuring to the treating medical team and a comfort to the relatives who witnessed the lack of response to standard treatment.

Carboplatin in BRCA1/2-mutated and triple-negative breast cancer BRCAness subgroups: the TNT Trial.

Germline mutations in BRCA1/2 predispose individuals to breast cancer (termed germline-mutated BRCA1/2 breast cancer, gBRCA-BC) by impairing homologous recombination (HR) and causing genomic instability. HR also repairs DNA lesions caused by platinum agents and PARP inhibitors. Triple-negative breast cancers (TNBCs) harbor subpopulations with BRCA1/2 mutations, hypothesized to be especially platinum-sensitive. Cancers in putative 'BRCAness' subgroups-tumors with BRCA1 methylation; low levels of BRCA1 mRNA (BRCA1 mRNA-low); or mutational signatures for HR deficiency and those with basal phenotypes-may also be sensitive to platinum. We assessed the efficacy of carboplatin and another mechanistically distinct therapy, docetaxel, in a phase 3 trial in subjects with unselected advanced TNBC. A prespecified protocol enabled biomarker-treatment interaction analyses in gBRCA-BC and BRCAness subgroups. The primary endpoint was objective response rate (ORR). In the unselected population (376 subjects; 188 carboplatin, 188 docetaxel), carboplatin was not more active than docetaxel (ORR, 31.4% versus 34.0%, respectively; P = 0.66). In contrast, in subjects with gBRCA-BC, carboplatin had double the ORR of docetaxel (68% versus 33%, respectively; biomarker, treatment interaction P = 0.01). Such benefit was not observed for subjects with BRCA1 methylation, BRCA1 mRNA-low tumors or a high score in a Myriad HRD assay. Significant interaction between treatment and the basal-like subtype was driven by high docetaxel response in the nonbasal subgroup. We conclude that patients with advanced TNBC benefit from characterization of BRCA1/2 mutations, but not BRCA1 methylation or Myriad HRD analyses, to inform choices on platinum-based chemotherapy. Additionally, gene expression analysis of basal-like cancers may also influence treatment selection.

Antiproliferative Effect of Lapatinib in HER2-Positive and HER2-Negative/HER3-High Breast Cancer: Results of the Presurgical Randomized MAPLE Trial (CRUK E/06/039).

PURPOSE: Not all breast cancers respond to lapatinib. A change in Ki67 after short-term exposure may elucidate a biomarker profile for responsive versus nonresponsive tumors. EXPERIMENTAL DESIGN: Women with primary breast cancer were randomized (3:1) to 10 to 14 days of preoperative lapatinib or placebo in a multicenter phase II trial (ISRCTN68509377). Biopsies pre-/posttreatment were analyzed for Ki67, apoptosis, HER2, EGFR, ER, PgR, pAKT, pERK, and stathmin by IHC. Further markers were measured by RT-PCR. Primary endpoint was change in Ki67. HER2(+) was defined as 2+/3+ by IHC and FISH(+). RESULTS: One hundred twenty-one patients (lapatinib, 94; placebo, 27) were randomized; of these, 21% were HER2(+), 78% were HER2(-) nonamplified, 26% were EGFR(+). Paired samples containing tumor were obtained for 98% (118 of 121). Ki67 fell significantly with lapatinib (-31%; P < 0.001), but not with placebo (-3%). Whereas Ki67 reduction with lapatinib was greatest in HER2(+) breast cancer (-46%; P = 0.003), there was a significant Ki67 decrease in HER2(-) breast cancer (-27%; P = 0.017) with 14% of HER2(-) breast cancer demonstrating ≥50% Ki67 reduction with lapatinib. Among HER2(+) patients, the only biomarker predictive of Ki67 response was the EGFR/HER4 ligand epiregulin (EREG) (rho = -0.7; P = 0.002). Among HER2(-) tumors, only HER3 mRNA levels were significantly associated with Ki67 response on multivariate analysis (P = 0.01). In HER2(-) breast cancer, HER2 and HER3 mRNA levels were highly correlated (rho = 0.67, P < 0.001), with all Ki67 responders having elevated HER3 and HER2 expression. CONCLUSIONS: Lapatinib has antiproliferative effects in a subgroup of HER2(-) nonamplified tumors characterized by high HER3 expression. The possible role of high HER2:HER3 heterodimers in predicting response to lapatinib merits investigation in HER2(-) tumors.

Rechallenging with anthracyclines and taxanes in metastatic breast cancer.

Adjuvant use of anthracycline-taxane combination therapy is an accepted strategy in the management of high-risk early-stage breast cancer. However, the introduction of this regimen raises the question of how best to manage those patients who relapse following adjuvant therapy, and whether there is a role for rechallenging in the metastatic setting with the same agent, or class of agent, that has been utilized in the adjuvant setting. This Review examines the evidence for rechallenging with both anthracyclines and taxanes, and highlights the issues that need to be examined in the context of future clinical trials.

Impact of estrogen deprivation on gene expression profiles of normal postmenopausal breast tissue in vivo.

Aromatase inhibitors play a key role in the clinical management of hormone receptor-positive breast cancer and have potential utility as chemopreventive agents. Further understanding of the molecular effects of estrogen and its deprivation in normal breast tissue may allow the development of biomarkers of risk of breast cancer and help to predict the value of chemoprevention with aromatase inhibitors. Core biopsies of normal breast tissue were taken before and after letrozole treatment from postmenopausal women in the LITMaS pilot prevention study. RNA was extracted from these samples and used for cDNA microarray analysis. Gene expression changes induced by letrozole treatment were much less extensive than observed in estrogen receptor-positive malignant tissue; however, overall, they correlated to a highly significant degree (rho = 0.511; P < 10(-20)). As well as some classically estrogen-associated genes, many genes associated with extracellular matrix remodeling were affected by estrogen deprivation in the normal breast in vivo. These data indicate for the first time that gene expression of normal breast tissue remains dependent on endogenous estrogens after the menopause. The modest degree of gene change suggests that intermediate markers of chemoprevention may be difficult to identify.

Effects of the aromatase inhibitor letrozole on normal breast epithelial cell proliferation and metabolic indices in postmenopausal women: a pilot study for breast cancer prevention.

The aromatase enzyme converts androgens to estrogens and is the therapeutic target for aromatase inhibitors in postmenopausal patients with estrogen receptor-positive metastatic breast cancer. Third-generation inhibitors such as letrozole are being considered as potential prophylactic agents for breast cancer. The rationale for their preventive application would be aided by knowledge of their effects on the normal breast and on other estrogen-dependent processes such as bone and lipid metabolism. Thirty-two women without active breast disease were recruited to 3-month treatment with letrozole (2.5 mg/day). Core-cut biopsies from the breast and blood samples were collected before and at the end of treatment. Plasma estradiol levels were markedly suppressed in all but two patients, who were excluded from the efficacy assessment. There was no significant change in the proliferation marker Ki67 (mean change, -23%; 95% confidence interval, -50% to +23%) or estrogen receptor in breast epithelial cells with treatment. Similarly, there were no significant changes in plasma levels of insulin-like growth factor I or lipid profiles. However, there was a significant increase (25%) in the levels of the bone resorption marker C-telopeptide crosslinks (CTx). We conclude that any prophylactic effect of letrozole is not likely to be dependent on antiproliferative effects on normal breast. Studies in healthy patients will need to recognize the potential for enhanced bone resorption.