Lynn Jongen

Tamoxifen metabolism and efficacy in breast cancer- a prospective multicentre trial

Purpose: Levels of endoxifen, the most active metabolite of tamoxifen, vary by the highly polymorphic cytochrome P450 (CYP) 2D6 enzyme. We prospectively investigated tamoxifen efficacy by serum endoxifen levels and the tamoxifen activity score (TAS). Experimental Design: A prospective observational multicenter study included postmenopausal women with an estrogen receptor–positive breast cancer receiving first-line tamoxifen, 20 mg daily in the neoadjuvant or metastatic setting, recruited between February 2009 and May 2014. The primary endpoint was the objective response rate (ORR) using RECIST criteria 1.0. Secondary endpoints were clinical benefit (CB), progression-free survival (PFS), and tolerability of tamoxifen. The main analysis used logistic regression to relate ORR to serum endoxifen levels after 3 months. Endpoints were also related to other tamoxifen metabolites and to TAS. Results: Endoxifen levels were available for 247 of all 297 patients (83%), of which 209 with target lesions (85%). Median follow-up time for PFS was 32.5 months, and 62% progressed. ORR and CB were 45% and 84%, respectively. ORR was not related to endoxifen, and the OR of ORR was 1.008 per μg/L increase in endoxifen (95% confidence interval, 0.971–1.046; P = 0.56). In general, none of the endpoints was associated with endoxifen levels, tamoxifen metabolites, or TAS. Conclusions: Under the prespecified assumptions, the results from this prospective clinical trial do not suggest therapeutic drug monitoring of endoxifen to be of clinical value in postmenopausal women treated with tamoxifen for breast cancer in the neoadjuvant or metastatic setting. Clin Cancer Res; 24(10); 2312–8. ©2018 AACR.

The prognostic performance of Adjuvant! Online and Nottingham Prognostic Index in young breast cancer patients

Background:Limited data are available on the prognostic performance of Adjuvant! Online (AOL) and Nottingham Prognostic Index (NPI) in young breast cancer patients.Methods:This multicentre hospital-based retrospective cohort study included young (⩽40 years) and older (55–60 years) breast cancer patients treated from January 2000 to December 2004 at four large Belgian and Italian institutions. Predicted 10-year overall survival (OS) and disease-free survival (DFS) using AOL and 10-year OS using NPI were calculated for every patient. Tools ability to predict outcomes (i.e., calibration) and their discriminatory accuracy was assessed.Results:The study included 1283 patients, 376 young and 907 older women. Adjuvant! Online accurately predicted 10-year OS (absolute difference: 0.7%; P=0.37) in young cohort, but overestimated 10-year DFS by 7.7% (P=0.003). In older cohort, AOL significantly underestimated both 10-year OS and DFS by 7.2% (P<0.001) and 3.2% (P=0.04), respectively. Nottingham Prognostic Index significantly underestimated 10-year OS in both young (8.5%; P<0.001) and older (4.0%; P<0.001) cohorts. Adjuvant! Online and NPI had comparable discriminatory accuracy.Conclusions:In young breast cancer patients, AOL is a reliable tool in predicting OS at 10 years but not DFS, whereas the performance of NPI is sub-optimal.

Gene-environment interactions involving functional variants: Results from the Breast Cancer Association Consortium.

Investigating the most likely causal variants identified by fine‐mapping analyses may improve the power to detect gene–environment interactions. We assessed the interplay between 70 single nucleotide polymorphisms identified by genetic fine‐scale mapping of susceptibility loci and 11 epidemiological breast cancer risk factors in relation to breast cancer. Analyses were conducted on up to 58,573 subjects (26,968 cases and 31,605 controls) from the Breast Cancer Association Consortium, in one of the largest studies of its kind. Analyses were carried out separately for estrogen receptor (ER) positive (ER+) and ER negative (ER–) disease. The Bayesian False Discovery Probability (BFDP) was computed to assess the noteworthiness of the results. Four potential gene–environment interactions were identified as noteworthy (BFDP < 0.80) when assuming a true prior interaction probability of 0.01. The strongest interaction result in relation to overall breast cancer risk was found between CFLAR‐rs7558475 and current smoking (ORint = 0.77, 95% CI: 0.67–0.88, pint = 1.8 × 10−4). The interaction with the strongest statistical evidence was found between 5q14‐rs7707921 and alcohol consumption (ORint =1.36, 95% CI: 1.16–1.59, pint = 1.9 × 10−5) in relation to ER– disease risk. The remaining two gene–environment interactions were also identified in relation to ER– breast cancer risk and were found between 3p21‐rs6796502 and age at menarche (ORint = 1.26, 95% CI: 1.12–1.43, pint =1.8 × 10−4) and between 8q23‐rs13267382 and age at first full‐term pregnancy (ORint = 0.89, 95% CI: 0.83–0.95, pint = 5.2 × 10−4). While these results do not suggest any strong gene–environment interactions, our results may still be useful to inform experimental studies. These may in turn, shed light on the potential interactions observed.

Withdrawal of hormone replacement therapy might affect multigene signature results in early luminal breast cancer

ABSTRACT In this case-report we established a discordance of luminal subtype between core needle biopsy results at breast cancer diagnosis and surgical specimen results after hormone replacement therapy withdrawal at diagnosis. This observation might suggest that short term change in hormonal environment prior to breast cancer surgery might affect multi-gene signature results.

Prognostic Value of the Progesterone Receptor by Subtype in Patients with Estrogen Receptor‐Positive, HER‐2 Negative Breast Cancer

BACKGROUND In estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER-2) negative breast cancers, the progesterone receptor (PR) is an independent prognostic marker. Little is known about the prognostic value of PR by tumor grade. We assessed this in two independent datasets. PATIENTS AND METHODS Women with primary operable, invasive ER+ HER-2 negative breast cancer diagnosed between 2000 and 2012, treated at University Hospitals Leuven, were included. We assessed the association of PR status and subtype (grade 1-2 vs. grade 3) with distant recurrence-free interval (DRFI) and breast cancer-specific survival. The interaction between PR status and subtype was investigated, and associations of PR status by subtype were calculated. The BIG 1-98 data set was used for validation. RESULTS In total, 4,228 patients from Leuven and 5,419 from BIG 1-98 were analyzed. In the Leuven cohort, the adjusted hazard ratio (HR) of PR-positive versus PR-negative tumors for DRFI was 0.66 (95% confidence interval [CI], 0.50-0.89). For the interaction with subtype (p = .34), the HR of PR status was 0.79 (95% CI, 0.61-1.01) in luminal A-like and 0.59 (95% CI, 0.46-0.76) in luminal B-like tumors. In luminal A-like tumors, observed 5-year cumulative incidences of distant recurrence were 4.1% for PR-negative and 2.8% for PR-positive tumors, and in luminal B-like 18.7% and 9.2%, respectively. In the BIG 1-98 cohort, similar results were observed; for the interaction with subtype (p = .12), the adjusted HR of PR status for DRFI was 0.88 (95% CI, 0.57-1.35) in luminal A-like and 0.58 (95% CI, 0.43-0.77) in luminal B-like tumors. Observed 5-year cumulative incidences were similar. CONCLUSION PR positivity may be more protective against metastatic relapse in luminal B-like versus luminal A-like breast cancer, but no strong conclusions can be made. In absolute risk, results suggest an absent PR is clinically more important in high compared with low proliferative ER+ HER-2 negative tumors. IMPLICATIONS FOR PRACTICE An absent progesterone receptor (PR) predicts a worse outcome in women treated for an estrogen receptor-positive, human epidermal growth factor receptor 2 negative breast cancer. As low proliferative tumors lacking PR are now also classified high risk, the prognostic value of PR across risk groups was studied. Despite a negative test for interaction of the prognostic value of PR by tumor grade, the magnitude of an absent PR on breast cancer relapse is much larger in high than in low proliferative breast cancers.

Abstract P2-03-05: Identification, clinical characteristics and treatment outcomes of somatic human epidermal growth factor receptor 2 (ERBB2) mutations in metastatic breast cancer patients

Background Metastatic breast cancer (MBC) is seen as incurable and advances in new therapies or targets are necessary. Targeted therapies against human epidermal growth factor receptor 2 (ERBB2) (also known as HER2) in tumors with ERBB2 overexpression due to gene amplification have improved patients outcomes. Besides ERBB2 amplification, this receptor can also be altered by somatic mutations (without ERRB2 amplification) that likely drive tumorigenesis. Neratinib, an irreversible pan-HER tyrosine kinase inhibitor, has recently been demonstrated to potently inhibit breast cancers that have amplification or activating mutations in ERBB2. This is the first study that thoroughly investigates the natural history of ERBB2 mutations in MBC patients. The primary study objectives are to 1) evaluate the frequency of ERBB2 mutations in a large MBC cohort, 2) understand standard clinical, pathological and patient characteristics associated with ERBB2 mutations, 3) identify other gene mutations/aberrations that may co-occur with ERRB2 mutations, 4) characterize treatment responses and outcomes to standard therapies in patients with ERBB2 mutant vs. wild-type tumors, and 5) determine if ERBB2 mutations can be detected from plasma ctDNA samples collected at baseline (not reported here). Patients and Methods This retrospective study included all MBC patients (primary metastatic or developed metastases during follow-up), independent of hormone receptor or HER2 amplification status, diagnosed between January 1st 2000 and July 31st 2015 at the Multidisciplinary Breast Center of University Hospitals Leuven, and for whom sufficient tumor material was available for DNA extraction. Extracted DNA from primary breast cancer tissues were subject to targeted NGS-based sequencing, to identify single nucleotide variants, insertion, deletion, and indels within exons 8, 17, 19, 20 and 21 of the ERBB2 gene. Results We established and validated a research use only next-generation sequencing assay across five exons of the ERBB2 gene. 1062 MBC patients were included and so far 177 patients were successfully screened for ERBB2 mutations resulting in an occurrence of n=10 (5.6%) in this population. The remaining patients are currently being screened for ERBB2 mutations and the overall results on all described endpoints will be available at the meeting. Conclusion ERBB2 mutations seem more frequent in MBC than previously thought based on the general early breast cancer population. In depth analysis of this large MBC cohort evaluating clinical characteristics and standard treatment outcomes of ERBB2 mutant MBC may provide further knowledge on this breast cancer subtype that may benefit from HER2-directed therapies which are currently under investigation in clinical trials. Citation Format: Jongen L, Floris G, Lambrechts D, Laenen A, Neven P, Cutler Jr. RE, Lalani AS, Wildiers H. Identification, clinical characteristics and treatment outcomes of somatic human epidermal growth factor receptor 2 (ERBB2) mutations in metastatic breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-03-05.

Abstract P5-08-31: Withdrawal of exogenous hormones affects prognostic multigene signature results in early luminal breast cancer

Background Early breast cancer (BC) outcomes are mainly estimated based on clinicopathological parameters and rarely include proliferation markers: (Ki-67), and multigene signatures (MGS), which are typically measured in tumors from resection specimens (RS). We believe that tumor proliferation can change within days of anti-estrogen use. However, little is known how proliferation changes after withdrawal of hormone replacement therapy (HRT) or oral anti-conception (OAC) after a core needle biopsy (CNB) shows BC. Hence, this study compares the Ki-67 labeling index and the MGS results in CNB and RS collected from a cohort of patients under OAC/HRT. Patients and Methods This retrospective study included consecutive women diagnosed with a grade 1-2, any pTN0-1, primary operable estrogen receptor-positive, human epidermal growth factor receptor 2-negative, and invasive ductal carcinoma between January 2013 and July 2014 at the Multidisciplinary Breast Center of University Hospitals Leuven were selected from a prospectively managed database. Ki-67 staining was performed on RS (Ki-67 RS ) to compare those who used HRT/OAC for at least 3 months at diagnosis and those not using OAC/HRT at diagnosis. OAC/HRT was always stopped between CNB and RS. Subsequently, we compared Ki-67 of the CNB (Ki-67 CNB ) with the matched RS in 15 patients with a low Ki-67 RS (14%) stopping OAC/HRT after CNB; revised standard pathology confirmed absence of tumor heterogeneity in all samples. In addition, in a subset of patients (≥50 years, Ki-67 RS ≤5%) we compared Ki-67 index and MGS results (MammaPrint (MP) and BluePrint, Agendia) from the CNB versus RS. Results 193 patients with a known Ki-67 RS were included; 38 patients (mean age of 55 years) were on OAC/HRT at CNB and 155 patients (mean age of 64 years) were not. The median time between stopping OAC/HRT and resection was 23 days (range 8-48 days). Ki-67 RS was RS (≤14%) and had a high matched Ki-67CNB (≥15%). In another subset of four out of 15 patients we compared CNB and RS (table1) where we observed changes in both Ki-67 and MGS. Conclusion Women on OAC/HRT, at diagnosis of an early luminal BC, are more likely to have a lower Ki-67 RS as those not using OAC/HRT. Our findings are likely explained by a sudden decrease in sex steroids after BC diagnosis, resulting in lower proliferation markers. As such, a lower hormonal environment by withdrawing HRT/OAC at BC diagnosis might underestimate proliferation markers used for prognostic and predictive purposes. Therefore we are currently testing this hypothesis in larger cohorts. Citation Format: Jongen L, De Vries P, Van Asten K, Lintermans A, Laenen A, Wildiers H, Floris G, Neven P. Withdrawal of exogenous hormones affects prognostic multigene signature results in early luminal breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-31.

Androgen deprivation by adrenal suppression using low-dose hydrocortisone for the treatment of breast carcinoma with apocrine features: a case report illustrating this new paradigm

We report on a postmenopausal patient with a secondary metastatic apocrine breast cancer successfully treated with low-dose hydrocortisone only following several lines of chemotherapy. The tumor cells in the primary and metastatic lesion exhibited a ‘triple-negative’ status (estrogen receptor (ER)-, progesterone receptor (PR)-, and human epidermal growth factor receptor 2 (HER2)-negative); the androgen receptor (AR) was strongly expressed. Twenty milligrams of hydrocortisone, a low substitution dose known to suppress adrenal steroid production, twice daily led to a clinical benefit lasting for one year, with symptom control, radiologically stable disease, and steady decrease in CA15.3. Our observation demonstrates that an AR-expressing apocrine breast cancer may respond to androgen deprivation, as an ER-positive breast cancer may benefit from estrogen deprivation. It highlights the importance of further research targeting the AR pathway in apocrine carcinoma, for which androgens represent the sole (known) steroid hormone stimulating tumor growth. Future clinical trials should not only focus on AR inhibitors like enzalutamide, but also on ablative modalities like low-dose hydrocortisone aiming at medical adrenalectomy. This method of androgen deprivation is largely available, cheap, and nearly devoid of toxicity.

Abstract OT2-1-05: Prospective multicenter study evaluating the effect of impaired tamoxifen metabolization on efficacy in breast cancer patients receiving tamoxifen in the neo-adjuvant or metastatic setting - The CYPTAM-BRUT 2 trial

Background Tamoxifen is commonly used to treat and prevent hormone receptor positive breast cancers. This drug is metabolized into more active metabolites by liver enzymes such as cytochrome P450 (CYP) enzymes. Endoxifen is considered to be the principal active metabolite of tamoxifen. As CYP enzymes are highly polymorphic in humans, endoxifen plasma levels are modulated by the patient’s genotype. It, however, is not yet clear if lowered endoxifen plasma levels have an effect on tamoxifen efficacy. This is the first prospective study where the association between endoxifen plasma concentrations, multiple CYP-genotypes and clinical outcome in postmenopausal patients treated with tamoxifen is investigated. Trial Design CYPTAM-BRUT 2 is a prospective multi-center open label, single-arm, non-randomized observational study. Postmenopausal women with measurable, estrogen receptor positive breast cancer receiving tamoxifen as neo-adjuvant or as first-line metastatic treatment are included in this study. The objective treatment response and clinical benefit are observed to investigate the efficacy of 20 mg tamoxifen daily. Patients are allowed to have started tamoxifen before inclusion but not more than three months. Further, if more than twelve months have passed after completion of the adjuvant therapy prior endocrine therapy in the adjuvant setting is allowed. Patients receiving neo-adjuvant tamoxifen will be assessed no more than four months after starting with tamoxifen. The primary endpoint is a statistical association between steady-state endoxifen plasma concentrations and the objective response rate (ORR) after 3-6 months of tamoxifen, under the assumption that the relationship is linear with an odds ratio (OR) of 1.49 per 10 nmol/L. Using available data on endoxifen concentrations, this OR is chosen to reflect an improvement from 10% ORR in the lowest endoxifen quartile to 30% in the highest endoxifen quartile when the overall ORR is around 18%. To have 90% power at a 5% significance level, 180 patients have to be included into the study. The main secondary study endpoint is the relation between endoxifen plasma concentrations and clinical benefit (CR+PR+SD at 6 months). The study has to include 270 patients to detect a statistically significant association with endoxifen with 90% power at a 5% significance level, assuming an OR of 1.28 per 10 nmol/L. This OR is chosen to reflect an improvement of clinical benefit at 6 months from 30% in the lowest endoxifen quartile to 50% in the highest endoxifen quartile (overall clinical benefit around 39%). For both endpoints the RECIST criteria are used. Other endpoints are progression-free survival, tolerability of tamoxifen treatment and the association between CYP2D6 genotype and clinical outcome. Patient accrualPatients from 22 participating centers in Belgium and Switzerland are included in this trial. In May 2014, the predefined sample size of 270 patients was reached. Follow-up of the last patients will continue until all required data are obtained (i.e blood samples and response evaluation). Citation Format: Kathleen Van Asten, Lynn Jongen, Anne-Sophie Dieudonne, Anneleen Lintermans, Chantal Blomme, Olivier Brouckaert, Diether Lambrechts, Hans Wildiers, Marie-Rose Christiaens, Dirk Timmerman, Ben Van Calster, Jan Decloedt, Patrick Berteloot, Didier Verhoeven, Markus Joerger, Khalil Zaman, Vincent Dezentje, Patrick Neven. Prospective multicenter study evaluating the effect of impaired tamoxifen metabolization on efficacy in breast cancer patients receiving tamoxifen in the neo-adjuvant or metastatic setting - The CYPTAM-BRUT 2 trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT2-1-05.