Abstract P6-08-03: Germline mutational landscape in 5422 individuals at risk for hereditary breast and ovarian cancer who underwent multi-gene panel testing

Background: The introduction of multi-gene panel testing and improved awareness under patients and physicians has led to an increase of individuals with known germline pathogenic variants in hereditary breast and ovarian cancer (HBOC) genes. Significant regional differences exist in germline mutational landscape. We aimed to report the findings from multi-gene panel testing in a large Belgian cohort of individuals at risk for HBOC.

Methods: All individuals who underwent multi-gene panel testing for HBOC at the Center for Human Genetics of the University Hospitals Leuven since the introduction of the panel were included (March 2016-April 2019). All included individuals were considered candidates for HBOC-panel testing by the requesting physician based on a personal or familial history of breast and/or ovarian cancer. Testing criteria from the Belgian Society of Human Genetics (www.beshg.be/download/guidelines/Guidelines_HBOC_2018.pdf) were met in the vast majority. The panel used was the BRCA Hereditary Cancer MASTR Plus® (Agilent, Belgium), with sequencing of BARD1, BRCA1, BRCA2, BRIP1, RAD51C, RAD51D, TP53, MRE11A, RAD50, NBN, FAM175A, ATM, PALB2, STK11, MEN1, PTEN, CDH1, MUTYH, CHEK2, BLM, XRCC2, EPCAM, MLH1, MSH6, PMS2 and MSH2. Sequencing was performed by NGS on a Miseq platform (Illumina). Genomic deletions and duplications in BRCA1 and BRCA2 were investigated with multiplex ligation-dependent probe amplification.

We hereby report on the frequency of pathogenic and likely pathogenic germline variants in this population.

Results: In 5422 individuals who underwent multi-gene panel testing, we detected 665 pathogenic or likely pathogenic variants in 639 patients (11,7%). In 25 patients (0.46%), more than one relevant alteration was detected with double heterozygosity in 24 individuals and triple heterozygosity in one. Germline variants in BRCA1 and BRCA2 were detected in 178 (3.3%) and 144 (2.7%) patients, resulting in a fraction of 26,4% and 21,4% of detected variants respectively. Relevant alterations in CHEK2, ATM, PALB2 and TP53 were observed in 135 (2.5%), 93 (1.7%), 26 (0.5%) and 11 (0.2%) patients respectively, accounting together for 39.3% of detected variants. Alterations in BRIP1/RAD51C/RAD51D were retrieved in 64 patients (1.2%) and alterations in mismatch-repair genes MSH6/MLH1/PMS2/MSH2 were detected in 0.3% of patients. These patients where dominantly referred for familial history of ovarian cancer. Furthermore, germline alterations in PTEN, CDH1 and BLM were observed in 3, 2 and 1 cases respectively. Double heterozygosity for ATM+CHEK2 and for ATM+BRCA2 were both observed in 3 cases. In the patient with triple heterozygosity, co-occurrence of pathogenic variants in BRCA2, ATM and CHEK2 was detected.

Conclusions: In a large Belgian cohort of 5422 individuals at risk for HBOC who underwent multi-gene panel testing, a pathogenic or likely pathogenic germline variant was detected in 11,7% of patients, and in 0,46% of patients double or triple heterozygosity for HBOC-variants was observed. Almost 40% of detected variants were alterations beyond BRCA correlated with hereditary breast cancer (CHEK2, ATM, PALB2 and TP53). Given the time-lag to predictive testing in families, a significant rise in healthy carriers with these non-BRCA alterations is expected in the upcoming years.

Citation Format: Kevin Punie, Griet Hoste, Griet Van Buggenhout, Ellen Denayer, Hilde Brems, Hilde Peeters, Ann Smeets, Ines Nevelsteen, Patrick Neven, Jan Ardui, Renate Prevos, Machteld Keupers, Chantal Van Ongeval, Giuseppe Floris, Christine Desmedt, Hans Wildiers, Geneviève Michils, Hilde Van Esch, Eric Legius. Germline mutational landscape in 5422 individuals at risk for hereditary breast and ovarian cancer who underwent multi-gene panel testing [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-03.

Abstract P3-07-14: Multigene signatures based risk estimates in early ER+/HER2- breast cancer: The predictive value of inexpensive statistical models and changes in adjuvant chemotherapy use

Background Multigene signatures (MGS) select women with estrogen receptor positive human epidermal growth factor receptor 2 negative (ER+/HER2-) breast cancers where adjuvant chemotherapy (aCT) can be avoided. However, MGS are expensive and not always reimbursed. We investigated the predictive value of six inexpensive statistical models in tumors with low or high risk of relapse based on MGS and investigated the change in decision to add chemotherapy following MGS results. Patients and Methods In this retrospective study, we evaluated patients diagnosed with primary operable ER+/HER2- lymph node negative or positive breast cancer diagnosed at University Hospitals Leuven between 2013 and 2018. Tumor tissue of the patients was analyzed by MammaPrint® (MP) (n=25), OncotypeDX® (ODX) (n=44) or Prosigna® (n=57) as there was uncertainty about benefit of aCT during multidisciplinary meeting (MDM). Magee equations (ME), Memorial Sloan Kettering simplified score (MSK), Breast Cancer Recurrence Score Estimator (BCRSE), OncotypeDXCalculator (ODXC), new Adjuvant! Online (nAOL) and PREDICT v2.0 were computed. TAILORx cut-offs were used for ODX. A 85% cut-off was used for the probability of a low (0-25) or high risk (26-100) ODX recurrence score for ODXC and a 5% cut-off was used for 10-year survival benefit with aCT for nAOL and PREDICT. Results All ME- and BCRSE-high cases were classified by MGS as high or intermediate and not as MGS-low risk (Table 1). None of the low risk classifications by ME and nAOL resulted in MGS-high risk with ODX. High risk classification with nAOL showed strong concordance with all MGS-high risk results. A switch in chemotherapy recommendation based on MDM decisions, was observed in 46% (58/126) of patients after MGS results. Following MGS testing, aCT was given to 57 patients which resulted in 17% relative and 10% absolute reduction. Conclusion Inexpensive statistical models based on clinico-pathological parameters can be useful in selecting patients that may need MGS testing. The use of MGS resulted in a substantial decisional switch and reduction in aCT-use.

Table 1 Predictive value of inexpensive statistical models in MGS tested tumors.MGS high risk (n=53)MGS low risk (n=52)ODX (n=17)MP (n=11)Prosigna (n=25)ODX (n=27)MP (n=14)Prosigna (n=11)MSK high (n=32)1038150ME high (n=7)411000BCRSE high (n=6)311000ODXC high (n=4)110010nAOL high (n=105)1772423123PREDICT high (n=47)7512850MSK low (n=37)3361145ME low (n=9)012202BCRSE low (n=50)3310967ODXC low (n=67)35131469nAOL low (n=21)041428PREDICT low (n=79)1061319911

Citation Format: Laurence Slembrouck, Isabelle Vanden Bempt, Hans Wildiers, Ann Smeets, Erik Van Limbergen, Philippe Moerman, Caroline Weltens, Kevin Punie, Griet Hoste, Els Van Nieuwenhuysen, Sileny Han, Ines Nevelsteen, Lynn Jongen, Patrick Neven, Giuseppe Floris. Multigene signatures based risk estimates in early ER+/HER2- breast cancer: The predictive value of inexpensive statistical models and changes in adjuvant chemotherapy use [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-07-14.

Decentralization of Next-Generation RNA Sequencing-Based MammaPrint® and BluePrint® Kit at University Hospitals Leuven and Curie Institute Paris

A previously developed and centrally validated MammaPrint® (MP) and BluePrint® (BP) targeted RNA next-generation sequencing (NGS) kit was implemented and validated in two large academic European hospitals. Additionally, breast cancer molecular subtypes by MP and BP RNA sequencing were compared with immunohistochemistry (IHC). Patients with early breast cancer diagnosed at University Hospitals Leuven and Curie Institute Paris were prospectively included between September 2017 and January 2018. Formalin-fixed paraffin-embedded tissue sections were analyzed with MP and BP NGS technology at the beta sites and with both NGS and microarray technology at Agendia. Raw NGS data generated on Illumina MiSeq instruments at the beta sites were interpreted and compared with NGS and microarray data at Agendia. MP and BP NGS molecular subtypes were compared to surrogate IHC breast cancer subtypes. Equivalence of MP and BP indices was determined by Pearson's correlation coefficient. Acceptable limits were defined a priori, based on microarray data generated at Agendia between 2012 and 2016. The concordance, the Negative Percent Agreement and the Positive Percent Agreement were calculated based on the contingency tables and had to be equal to or higher than 90%. Out of 124 included samples, 48% were MP Low and 52% High Risk with microarray. Molecular subtypes were BP luminal, HER2 or basal in 82%, 8% and 10% respectively. Concordance between MP microarray at Agendia and MP NGS at the beta sites was 91.1%. Concordance of MP High and Low Risk classification between NGS at the beta sites and NGS at Agendia was 93.9%. Concordance of MP and BP molecular subtyping using NGS at the beta sites and microarray at Agendia was 89.5%. Concordance between MP and BP NGS subtyping, and IHC was 71.8% and 76.6%, for two IHC surrogate models. The MP/BP NGS kit was successfully validated in a decentralized setting.

Abstract 1406: Multigene signatures based risk estimates in ER+/HER2- breast cancers: The predictive value of inexpensive statistical models and changes in adjuvant chemotherapy use

Background Multigene signatures (MGS) select women with estrogen receptor positive human epidermal growth factor receptor 2 negative (ER+/HER2-) breast cancers where adjuvant chemotherapy (aCT) can be avoided. However, MGS are expensive and not always reimbursed. We investigated the predictive value of five inexpensive statistical models in tumors with low or high risk of relapse based on MGS and investigated the change in decision to add chemotherapy following MGS results.

Patients and Methods In this retrospective study, we evaluated patients diagnosed with primary operable ER+/HER2- lymph node negative or positive breast cancer diagnosed at University Hospitals Leuven between 2013 and 2018. Patients were analyzed by MammaPrint® (MP) (n=24), OncotypeDX® (ODX) (n=44) or Prosigna®(n=57) as there was uncertainty about benefit of aCT during multidisciplinary meeting (MDM). Magee equations (ME), Memorial Sloan Kettering simplified score (MSK), Breast Cancer Recurrence Score Estimator (BCRSE), new Adjuvant! Online (nAOL) and PREDICT v2.0 were computed. TAILORx cut-offs were used for ODX. A 5% cut-off was used for 10-year survival benefit with aCT for nAOL and PREDICT.

Results All ME- and BCRSE-high cases were classified by MGS as high or intermediate and not as MGS-low risk, as shown in Table 1. None of the low risk classifications by ME and nAOL resulted in MGS-high risk with ODX. High risk classification with nAOL showed strong concordance with all MGS-high risk results. Chemotherapy switch according to MGS results was observed in 46% (57/125) of patients. Following MGS testing, aCT was given to 56 patients which resulted in 19% relative and 10% absolute reduction.

Conclusion Inexpensive statistical models based on pathologic parameters can be useful to select patients who may need MGS testing. Integration of MGS into MDM decisions, resulted in a substantial decisional switch and reduction in aCT administration.

Table 1Predictive value of inexpensive statistical models in MGS tested tumors.MGS high risk (n=52)MGS low risk (n=52)ODX (n=17)MP (n=10)Prosigna (n=25)ODX (n=27)MP (n=14)Prosigna (n=11)MSK high59% (10/17)30% (3/10)32% (8/25)4% (1/27)36% (5/14)0% (0/11)ME high24% (4/17)10% (1/10)4% (1/25)0% (0/27)0% (0/14)0% (0/11)BCRSE high0% (0/17)10% (1/10)4% (1/25)0% (0/27)0% (0/14)0% (0/11)nAOL high100% (17/17)60% (6/10)96% (24/25)85% (23/27)86% (12/14)27% (3/11)PREDICT high47% (8/17)40% (4/10)48% (12/25)26% (7/27)36% (5/14)0% (0/11)MSK low18% (3/17)30% (3/10)24% (6/25)41% (11/27)29% (4/14)46% (5/11)ME low0% (0/17)10% (1/10)8% (2/25)7% (2/27)0% (0/14)18% (2/11)BCRSE low18% (3/17)30% (3/10)40% (10/25)26% (7/27)43% (6/14)64% (7/11)nAOL low0% (0/17)40% (4/10)4% (1/25)15% (4/27)14% (2/14)73% (8/11)PREDICT low53% (9/17)60% (6/10)52% (13/25)74% (20/27)64% (9/14)100% (11/11)

Citation Format: Laurence Slembrouck, Giuseppe Floris, Hans Wildiers, Ann Smeets, Erik Van Limbergen, Philippe Moerman, Caroline Weltens, Kevin Punie, Griet Hoste, Els Van Nieuwenhuysen, Sileny Han, Ines Nevelsteen, Lynn Jongen, Patrick Neven, Isabelle Vanden Bempt. Multigene signatures based risk estimates in ER+/HER2- breast cancers: The predictive value of inexpensive statistical models and changes in adjuvant chemotherapy use [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1406.

Abstract P3-03-32: Monocentric experience with the sentinel lymph node biopsy prior to neoadjuvant chemotherapy in clinically lymph node negative early breast cancer

Background

In patients with clinically lymph node negative (cN0) early breast cancer (EBC) treated with neoadjuvant chemotherapy (NACT), the sentinel lymph node biopsy (SLNB) can be performed before or after NACT. We report safety of axillary staging performing the SLNB prior to NACT in cN0 EBC and estimate NACT-induced downstaging to ypN0 in previously NACT-treated cN1 EBC, to make an assumption for avoiding axillary lymph node dissection (ALND) if SLNB was done after NACT.

Patients and Methods

Monocentric retrospective study of consecutive triple negative (TNBC) and HER-2 amplified BC patients treated with standard NACT. cN0 patients had SLNB before NACT followed by local therapy. Axillary lymph node dissection (ALND) post-NACT was performed in all cN1 and in cN0 cases with a positive or failed SLNB. Using descriptive statistics, we here report SLNB-detection and SLNB-positive rate, SLNB-operative complications, complete tumor regression in the breast (ypT0/is) and disease-free survival (DFS) for cN0 cases and NACT-induced downstaging to ypN0 in previously NACT-treated cN1 EBC.

Results

We included 245 NACT-treated patients; 119 cN0 and 126 cN1. SLNB-detection rate in cN0 cases was 99,2%; 25 or 21% had ≥ 1 involved SLN, 21.8% experienced SLNB related-complications (e.g. infection, seroma, hematoma) leading to NACT-delay in 3 and interruption in 1 patient. Median start of NACT after SLNB was 7 days (range 1-20 days). In patients with a positive SLNB, there were no additional involved nodes in the ALND. In 5 of these patients, therapy response in a lymph node was described. Complete tumor regression in the breast (ypT0/is) was 52% in SLNB-positive and 59,1% in SLNB-negative cN0 cases. NACT-induced ypN0 was 61% in cN1 cases. At 30 months of median follow-up (range 1-86 months), DFS was 93,2% (4.2% metastatic; no axillary relapse) in cN0 cases. Median DFS was better for patients with complete tumor regression in the breast as compared to those with partial response; 95.6% and 90% respectively.

Conclusion

In conclusion, performing SLNB before NACT in cN0 cases is a safe and accurate method. While some pN1(sn) could have avoid ALND by NACT-induced axillary down-staging, based on our assumption, long term follow-up is needed to conclude whether SLNB after NACT is safe.

Keywords: Breast cancer, neoadjuvant chemotherapy, timing sentinel lymph node biopsy

Citation Format: Delameilleure M, Smeets A, Nevelsteen I, Han S, Van Nieuwenhuysen E, Berteloot P, Hoste G, Salihi R, Van Ongeval C, Keupers M, Prevos R, Wildiers H, Punie K, Van Limbergen E, Weltens C, Janssen H, Floris G, Vergote I, Neven P. Monocentric experience with the sentinel lymph node biopsy prior to neoadjuvant chemotherapy in clinically lymph node negative early breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-32.

Abstract P4-02-07: Comparison of breast cancer molecular subtyping by Immunohistochemistry and by BluePrint® next generation RNA sequencing-based test at University Hospitals Leuven and Curie Institute Paris

Background

MammaPrint® (MP) and BluePrint® (BP) are microarray-based tests with MP being prognostic for distant recurrence and BP enabling stratification into breast cancer molecular subtypes (Luminal, HER2, Basal-type). Recently, a CE marked MP and BP targeted RNA Next Generation Sequencing (NGS)-based kit was developed at Agendia and validated at University Hospitals Leuven and Curie Institute Paris. Here we compare breast cancer molecular subtype stratification defined by immunohistochemistry (IHC) and by MP and BP NGS- and microarray- based tests.

Patients and Methods

In this study, 124 primary operable invasive breast cancer patients were included at University Hospitals Leuven and at Curie Institute (n=80 Leuven; n=44 Curie) with the following histological subtypes: ductal-NOS (n=100), lobular (n=16), mucinous (n=3), tubular (n=2), others (n=3). Patients with bilateral breast cancer or with >3 positive lymph nodes were excluded. Surrogate breast cancer subtypes based on IHC were defined as follows: luminal if ≥10% estrogen receptor (ER) expression; triple negative if <10% ER and progesterone receptor (PR) expression and HER2 stained negative by IHC and/or FISH; HER2+ if HER2 receptor stained positive (2+ or 3+) by IHC and/or FISH. Luminal subtypes were further stratified into Luminal A-like (HER2 negative, Ki-67<14%, PR≥20%) and Luminal B-like (HER2 negative or positive, Ki-67 ≥14%, PR<20%). When Ki-67% was not available, tumors with grade 1 or 2 were classified as Luminal A-like and with grade 3 as Luminal B-like. IHC subtypes were compared to the BP NGS and microarray molecular subtypes (Luminal-, HER2- and Basal-type). To further stratify BP luminal type tumors, MP test was used as follows: Luminal A (BP Luminal and MP low risk) and Luminal B (BP Luminal and MP high risk).

Results

Concordance between IHC and MP/BP NGS subtyping was 75.0% (93/124), while concordance between MP/BP on NGS and microarray was 89.5% (111/124). MP/BP NGS subtyping identified more low risk Luminal A tumors compared to IHC (54.0%, (67/124) vs 44.3% (55/124)). Notably, concordance was excellent for triple-negative and, to less extent for HER2 driven tumors (Luminal B-like-HER2 positive and HER2+).

IHC vs. MP/BP NGS molecular subtyping (n=124)  MP/BP NGSIHCLuminal ALuminal BHER2-positiveBasalTotalLuminal A-like4690055Luminal B-like, HER2-negative16210037Luminal B-like, HER2-positive565016HER2-positive00303Triple negative0101213Total6737812124Microarray vs MP/BP NGS molecular subtyping (n=124)  MP/BP NGSMicroarrayLuminal ALuminal BHER2 positiveBasalTotalLuminal A6040064Luminal B7310038HER2-positive028010Basal0001212Total6737812124

Conclusion

This study shows a discordance of 25.0% between IHC and BP/MP NGS subtyping. This is in line with previous findings where IHC was compared to molecular subtyping based on microarray (Viale 2017, Whitworth 2014) underlining the complementarity of genomic testing in early stage breast cancer. Moreover, we observed a high concordance between NGS and microarray molecular subtyping, which suggests a successful translation of the MP/BP microarray test to a MP/BP NGS test.

Citation Format: Darrigues L, Slembrouck L, Mittempergher L, Delahaye LJ, Vanden Bempt I, Vander Borght S, Vliegen L, Sintubin P, Raynal V, Bohec M, Reyes C, Rapinat A, Helsmoortel C, Jongen L, Hoste G, Neven P, Wildiers H, Smeets A, Nevelsteen I, Punie K, Van Nieuwenhuysen E, Han S, Laurent C, Vincent-Salomon A, Laas-Faron E, Witteveen AT, Neijenhuis S, Glas AM, Floris G, Reyal F. Comparison of breast cancer molecular subtyping by Immunohistochemistry and by BluePrint® next generation RNA sequencing-based test at University Hospitals Leuven and Curie Institute Paris [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-02-07.

Abstract P4-08-25: Decentralized beta testing of MammaPrint and BluePrint NGS kit at University Hospitals Leuven and Curie Institute Paris

Background

Many countries restrict patient material exchange to central diagnostic laboratories abroad, limiting access to assays like MammaPrint® (MP) and BluePrint® (BP). Both assays are microarray-based, with MP being prognostic for distant recurrence and BP for molecular subtyping of breast cancer (Luminal-, HER2-, and Basal-type). To increase accessibility, decentralization is required with Next Generation Sequencing (NGS) being the preferred testing platform given that most diagnostic laboratories have the technology in place. The aim of this beta testing study is to validate a previously developed and centrally validated MP and BP NGS kit for RNA samples in two large tertiary academic hospitals in Europe.

Patients and Methods

Patients with early breast cancer diagnosed at the Multidisciplinary Breast Center at University Hospitals Leuven and Curie Institute Paris were prospectively included between September 2017 and January 2018. Patients with bilateral breast cancer or presenting with more than 3 positive lymph nodes were excluded. Only patients with invasive ductal and invasive lobular carcinoma were included. Twenty tissue sections were cut from formalin-fixed, paraffin-embedded (FFPE) blocks; 10 tissue sections were analyzed at the local site using the MP and BP NGS kit, and 10 tissue sections were analyzed at Agendia using the same kit and procedure, as well as with the golden standard method (gene expression microarrays). Targeted RNA sequencing of the 70 MP and 80 BP signature genes was performed on Illumina MiSeq instruments. The raw NGS data generated at the local test sites was sent through a secure file transfer protocol server to Agendia for interpretation and comparison with microarray and NGS performed in the Agendia laboratories. We aimed for a minimum concordance rate between MP and BP outcome of 90% between each local site and Agendia's centralized site.

Results

In this study, 116 early breast cancer patients were included (73 from University Hospitals Leuven and 43 from Curie Institute). Out of these patients, 52% were MP Low Risk and 48% MP High Risk according to microarray. The patients had a BP luminal, HER2 or basal subtype in respectively 83%, 9% and 8%. Concordance between MP microarray obtained from Agendia and MP NGS obtained from the local sites was 91.4%. Concordance between MP High and Low Risk classification between NGS Leuven versus NGS Agendia was 92.1% and between NGS Curie versus NGS Agendia 95.3%. For BP subtype outcomes, the results from microarray versus NGS for all patients combined from both local sites gave a 98.3% concordance and NGS Agendia versus NGS from each local site gave a 100% concordance.

Conclusion

The MP and BP NGS kit was successfully validated in a decentralized setting, showing high concordance between results obtained at three different sites. There was a clear benefit of having well-trained NGS experienced diagnostic technical teams. The MP and BP NGS kit the first FFPE targeted RNA sequencing based multigene signature for breast cancer care, will provide a high and equal standard of MP and BP gene expression testing for breast cancer in a decentralized setting.

Citation Format: Slembrouck L, Laurent C, Delahaye LJ, Mittempergher L, Vanden Bempt I, Vander Borght S, Darrigues L, Vliegen L, Sintubin P, Raynal V, Bohec M, Reyes C, Rapinat A, Helsmoortel C, Jongen L, Hoste G, Neven P, Wildiers H, Smeets A, Nevelsteen I, Punie K, Van Nieuwenhuysen E, Han S, Salomon AV, Faron EL, Cynober T, Witteveen AT, Neijenhuis S, Glas AM, Reyal F, Floris G. Decentralized beta testing of MammaPrint and BluePrint NGS kit at University Hospitals Leuven and Curie Institute Paris [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-25.

Abstract P1-15-04: Breast cancer recurrence and predictors for recurrence despite pathologic complete response following neoadjuvant chemotherapy

Introduction

Breast cancer patients with a high-risk tumor (for example Triple Negative Breast Cancer) who achieve a pathological complete response (pCR) following neoadjuvant chemotherapy (NACT) have a better outcome compared to patients with residual disease at surgery. This study investigated Breast Cancer Free Survival (BCFS) and predictors for distant relapse despite pCR.

Methods

Monocentric retrospective study of 243 consecutive breast cancer patients who achieved pCR (ypT0/is ypN0/N0(i+)) after treatment with NACT in UZ Leuven between 01/2000 and 08/2017. 58% had stage III breast cancer, 40% Triple Negative Breast Cancer (TNBC) and 47% HER2 pos breast cancer. BCFS was defined as any breast cancer related event (local, contra-lateral, regional, metastatic) that first appeared. Primary endpoints were frequency of BCFS and predictors for metastatic relapse: patient demographics (age, body mass index (BMI)) and tumor characteristics (TNM stage, histological type, hormonal receptor status). Secondary endpoints were breast cancer specific survival (BCSS) and overall survival (OS). Statistical analysis was performed using the Statistical Package for the Social Sciences software (SPSS, version 25). The Kaplan Meier method was used for survival analysis.

Results

Of 1167 breast cancer patients undergoing neoadjuvant treatment, 243 patients (20,8%) achieved pCR and were included. Median follow up was 57 months (range 9-252 months). 22 (9.1%) developed tumor progression; 20 (8.2%) metastatic and 2 (0.8%) contralateral. First metastatic site was the brain in 11/20 patients (55%) and 14/22 (64%) died of breast cancer. Higher clinical tumor stage at diagnosis predicted metastatic relapse (stage I-II 2.9%; stage III 12.1%). Patients with a BMI ≤25 kg/m2 had less metastatic relapse than patients with BMI >25kg/m2 (3.8% versus 12.0%), better OS (94.6% vs 88.0%) and BCSS (97.7 vs 91.7%). Neither tumor type (TNBC 8.2%; HER2-pos 8.1%; HR-pos/HER2 neg 9.3%) nor younger age < 36yrs (3.3% versus 8.9%) was prognostic for post-pCR relapse. There is a lower OS (mean 174m versus 231m, 95% CI 158-190m, median 208m) and BCSS (mean 191m versus 253m, 95% CI 182-200m) in cN1-3 versus cN0 disease at diagnosis.

Conclusion

Despite NACT-induced pCR, a small proportion (9.1%) will develop a metastatic relapse after a median follow-up of 57 months. We found that a higher stage at diagnosis and a higher BMI were prognostic for worse BCFS while age <36 y and negative hormonal receptor status were not prognostic. cN+ at diagnosis and a BMI >25 predict worse OS and BCSS.

Citation Format: Borremans K, Berteloot P, Van Nieuwenhuysen E, Han S, Hoste G, Wildiers H, Punie K, Smeets A, Nevelsteen I, Floris G, Van Ongeval C, Keupers M, Prevos R, Van Limbergen E, Menten J, Weltens C, Janssen H, Vergote I, Neven P. Breast cancer recurrence and predictors for recurrence despite pathologic complete response following neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-04.

Abstract P5-09-05: Hereditary breast cancer beyond BRCA: Clinical and histopathological characteristics in patients with germline CHEK2, ATM, PALB2 and TP53-mutations

Background

The introduction of multi-gene panel testing in the diagnosis of hereditary breast and ovarian cancer (HBOC) has led to an important increase in the detection of breast cancer predisposition genes other than BRCA1 and BRCA2.

Methods

All individuals who underwent HBOC-testing at our institution since the introduction of multi-gene panel testing were included (March 2016-August 2017). In this retrospective analysis, the BRCA Hereditary Cancer MASTR Plus® panel is used (Multiplicom, Belgium), with sequencing of BARD1, BRCA1, BRCA2, BRIP1, RAD51C, RAD51D, TP53, MRE11A, RAD50, NBN, FAM175A, ATM, PALB2, STK11, MEN1, PTEN, CDH1, MUTYH, CHEK2, BLM, XRCC2, EPCAM, MLH1, MSH6, PMS2, MSH2.

In breast cancer patients with a recurrent germline alteration, age and TNM stage at diagnosis, histological subtype, grade of differentiation and molecular surrogate subtype were recorded. Given the low numbers of TP53-carriers diagnosed by HBOC testing, also patients with a germline TP53-mutation diagnosed by targeted sequencing at our institution were included. Statistical analysis were performed with SPSS version 25.

Results

In 11.9 % of 2806 patients who underwent panel testing, a germline pathogenic alteration was detected. BRCA1 and BRCA2 were the most prevalent alterations, detected in respectively 3.35 and 2.92 % of patients. Germline alterations in CHEK2, ATM , PALB2 and TP53 were detected in respectively 2.5 %, 1.1 %, 0.5 % and 0.1 %. In 1 % of patients, germline alterations were retrieved that only contribute to ovarian cancer risk (BRIP, RAD51C, RAD51D). Germline DNA mismatch repair alterations were detected in 0.39 % of patients.

The median age at onset of breast cancer in patients with germline CHEK2-, ATM-, PALB2- and TP53-mutations was 47, 53, 39 and 33 years respectively. The age of breast cancer diagnosis in patients with germline TP53-alterations was significantly younger compared to patients with CHEK2-mutations (p = 0.01), ATM-mutations (p = 0.01) and PALB2-mutations (p = 0.04). In situ carcinomas were diagnosed in respectively 9 %, 11 % and 11 % of patients with CHEK2-, PALB2- and TP53-mutations. Patients with CHEK2, ATM, PALB2 and TP53-alterations were diagnosed with ≥T3-tumors in respectively 13 %, 12 %, 33 % and 22 %. Nodal status at diagnosis was negative in 40-60 % in these 4 subgroups. Upfront metastatic disease was diagnosed only in 2/43 CHEK2-carriers. More than half of the breast cancer diagnoses were luminal tumors in CHEK2-, ATM- and PALB2-carriers, while cases with germline TP53-alterations only presented with luminal cancers in 22 % in our series.

Conclusion

Almost half of the pathogenic mutations detected in HBOC-genes are alterations in genes other than BRCA1 and BRCA2. CHEK2-mutations are by far the most prevalent, followed by ATM, PALB2 and TP53.

The range of the CHEK2- and ATM-population was wider then expected at the lower-age boundary. The age of breast cancer diagnosis in patients with germline TP53-mutations was significantly younger compared to patients with CHEK2-, ATM- and PALB2-mutations. The distribution of the histological subtypes and grade of differentiation was not suggestive of a specific correlation with germline mutation status.

Citation Format: Hoste G, D'Hoore P, Legius E, Van Buggenhout G, Floris G, Wildiers H, Han SN, Van Nieuwenhuysen E, Berteloot P, Smeets A, Nevelsteen I, Weltens C, Janssen H, Van Limbergen E, Neven P, Punie K. Hereditary breast cancer beyond BRCA: Clinical and histopathological characteristics in patients with germline CHEK2, ATM, PALB2 and TP53-mutations [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-09-05.

Juvenile Papillomatosis: A Case Report

Juvenile papillomatosis of the breast, also known as Swiss cheese disease, is a rare and benign proliferative disorder affecting young women. These patients tend to have a strong family history of cancer. The lesion typically presents as a localized mass without sharp borders. Clinical presentation resembles that of a precancerous lesion. For this reason, JP is often misdiagnosed in the preoperative period. However postoperative histopathological examination reveals distinct microscopic features, such as duct papillomatosis, cysts and sclerosing adenosis, which confirm the diagnosis of juvenile papillomatosis. We report two cases of juvenile papillomatosis. Both cases were preoperatively diagnosed as benign proliferative lesions with fibrocystic changes. However, after surgical excision, histopathological examination showed juvenile papillomatosis. Interestingly, both patients had a strong family history of breast cancer in both the paternal and maternal line. More research is needed to assess the correlation between a family history of breast cancer and the juvenile papillomatosis.

Correction to: Unexpected Benefit from Alpelisib and Fulvestrant in a Woman with Highly Pre-treated ER-Positive, HER2-Negative PIK3CA Mutant Metastatic Breast Cancer

Dr. Arteaga serves on an Advisory Board for Novartis and was a consultant for AstraZeneca from 2015 to 2016. All other authors declare that they have no competing interests.

Unexpected Benefit from Alpelisib and Fulvestrant in a Woman with Highly Pre-treated ER-Positive, HER2-Negative PIK3CA Mutant Metastatic Breast Cancer

We present the case of a postmenopausal patient with a secondary metastatic ER-positive, HER2-negative breast cancer who was successfully treated with fulvestrant and alpelisib following six lines of therapy. The tumour showed two uncommon PIK3CA mutations, and with the combination of alpelisib and fulvestrant the patient went from ECOG grade 3, before the start of this therapy, to ECOG grade 1 during treatment until progressive disease after 6 months. This unexpected benefit emphasizes the importance of performing a Next Generation Sequencing (NGS)-based assay to screen for several cancer genes in the metastatic setting, even after more than four lines of therapy and a high ECOG grade. Moreover, the use of alpelisib may be beneficial for uncommon PIK3CA mutations.

Palbociclib in highly pretreated metastatic ER-positive HER2-negative breast cancer

PURPOSE

We aimed to investigate the role of palbociclib, a first-in-class cyclin-dependent kinase 4 and 6 inhibitor, in postmenopausal women with highly pretreated endocrine therapy-resistant metastatic breast cancer (MBC).

METHODS

Between 28 September 2015 and 14 March 2017, a compassionate use program was established in the University Hospitals Leuven in which 82 postmenopausal women with estrogen receptor-positive, HER2-negative MBC were included after at least four lines of systemic treatment. The efficacy and safety analysis was performed in 82 patients who had received at least one dose of palbociclib and who had at least 6-month follow-up at the data cut-off point. The primary objective was the evaluation of efficacy of the combination of palbociclib and endocrine therapy with clinical benefit as primary endpoint, defined as the absence of progressive disease and being on treatment for at least 6 months. Secondary objectives were the evaluation of toxicity and the identification of potential predictors for clinical benefit.

RESULTS

The median age of the patients was 67.1 years (range 34.8-85.9) at the time of inclusion. The average duration of treatment was 5.6 months (range 1-19), with a median progression-free survival of 3.17 (95% CI 2.76-4.70) months. At the data cut-off point, 10 patients were still on treatment with palbociclib. In this highly pretreated setting, 34 patients experienced no progressive disease within 6 months, resulting in an overall clinical benefit rate (CBR) of 41.5%. 20.7% (17/82) showed stable disease for ≥ 9 months and 13.4% for ≥ 12 months. None of the investigated predicting factors were significantly associated with clinical benefit at 6 months. For 43.9% of the patients, treatment delay or dose reduction was indicated.

CONCLUSIONS

Palbociclib in combination with endocrine therapy shows an unexpectedly high CBR and favorable safety profile in heavily pretreated endocrine-resistant estrogen receptor-positive, HER2-negative MBC patients.

Abstract P5-21-22: Palbociclib in highly pretreated metastatic ER-positive HER-2 negative breast cancer

Palbociclib, a first-in-class CDK 4/6 inhibitor, in combination with letrozole or fulvestrant is now licensed for the first or second line treatment of postmenopausal women with hormone-sensitive HER-2 negative metastatic breast cancer (MBC), but its activity in later lines is unknown. In Belgium, a compassionate Use Program (CUP) was temporarily established to provide palbociclib after at least 4 lines of systemic treatment for MBC.

The UZ Leuven Multidisciplinary Breast Center included 82 patients in this CUP from September 28th 2015 to March 14th 2017. This analysis describes retrospectively collected efficacy (Revised RECIST guideline, version 1.1) and safety data from 68 patients with at least 6 months follow-up at the data cut-off point. The primary endpoint was clinical benefit, defined as being on treatment for at least 6 months (CR + PR + SD). Most of the patients (89.7%) used palbociclib in combination with letrozole. Other combinations are with tamoxifen (2.9%), fulvestrant (2.9%), exemestane (1.5%), anastrazole (1.5%) and megestrol (1.5%).

At the data cut-off point, 18 patients are still on-treatment with palbociclib. The average duration of treatment is 5.7 months [range 2m- 17m]. The mean age of the patients was 66.3 years [range 34.8y – 85.9y] at the time of inclusion. Patients had had an average of 5.7 lines of systemic therapy [range 4 – 11 lines] before starting palbociclib, which was in 61.8% at least one line of chemotherapy. In this highly pretreated setting, 29 patients experienced stable disease lasting ≥ 6 months, resulting in an overall clinical benefit rate of 42.6%. 19.1% (13/68) showed stable disease for ≥ 9 months and 8% for ≥ 12 months. The subjective tolerance of the combination treatment was good, with 38% (26/68) of the patients discontinuing or delaying treatment following adverse events which were in the vast majority hematologic but asymptomatic. No factors predicting clinical benefit could be identified: use of chemotherapy before starting Palbociclib (p = 0.4644), age (p = 0.7029), time between primary breast cancer diagnosis and starting palbociclib (p = 0.1919) or time between first metastasis and starting palbociclib (p = 0.1108) and bone-only disease (p = 1,0000) were not significantly associated with clinical benefit at 6 months.

These data not only support the findings of the PALOMA studies, but also show unexpectedly high clinical benefit and safety of palbociclib in heavily pretreated endocrine-resistant hormone receptor positive HER-2 negative advanced breast cancer.

An update of these data will be presented.

Citation Format: Hoste G, Punie K, Wildiers H, Neven P, Berteloot P, Van Nieuwenhuysen E, Han S, Concin N, Salihi R, Lefever I, Vergote I. Palbociclib in highly pretreated metastatic ER-positive HER-2 negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-22.

The predictive value of quantitative fibronectin testing in combination with cervical length measurement in symptomatic women

BACKGROUND

The combination of the qualitative fetal fibronectin test and cervical length measurement has a high negative predictive value for preterm birth within 7 days; however, positive prediction is poor. A new bedside quantitative fetal fibronectin test showed potential additional value over the conventional qualitative test, but there is limited evidence on the combination with cervical length measurement.

OBJECTIVE

The purpose of this study was to compare quantitative fetal fibronectin and qualitative fetal fibronectin testing in the prediction of spontaneous preterm birth within 7 days in symptomatic women who undergo cervical length measurement.

STUDY DESIGN

We performed a European multicenter cohort study in 10 perinatal centers in 5 countries. Women between 24 and 34 weeks of gestation with signs of active labor and intact membranes underwent quantitative fibronectin testing and cervical length measurement. We assessed the risk of preterm birth within 7 days in predefined strata based on fibronectin concentration and cervical length.

RESULTS

Of 455 women who were included in the study, 48 women (11%) delivered within 7 days. A combination of cervical length and qualitative fibronectin resulted in the identification of 246 women who were at low risk: 164 women with a cervix between 15 and 30 mm and a negative fibronectin test (<50 ng/mL; preterm birth rate, 2%) and 82 women with a cervix at >30 mm (preterm birth rate, 2%). Use of quantitative fibronectin alone resulted in a predicted risk of preterm birth within 7 days that ranged from 2% in the group with the lowest fibronectin level (<10 ng/mL) to 38% in the group with the highest fibronectin level (>500 ng/mL), with similar accuracy as that of the combination of cervical length and qualitative fibronectin. Combining cervical length and quantitative fibronectin resulted in the identification of an additional 19 women at low risk (preterm birth rate, 5%), using a threshold of 10 ng/mL in women with a cervix at <15 mm, and 6 women at high risk (preterm birth rate, 33%) using a threshold of >500 ng/mL in women with a cervix at >30 mm.

CONCLUSION

In women with threatened preterm birth, quantitative fibronectin testing alone performs equal to the combination of cervical length and qualitative fibronectin. Possibly, the combination of quantitative fibronectin testing and cervical length increases this predictive capacity. Cost-effectiveness analysis and the availability of these tests in a local setting should determine the final choice.

Robotic hysterectomy using the Vessel Sealer for myomatous uteri: technique and clinical outcome

OBJECTIVE

Robotic procedures using the Vessel Sealer are not well reported in the literature, especially given the advantages of sealing devices already studied in standard laparoscopic procedures. This study reports our experience with the EndoWrist(®) One™ Vessel Sealer in robotic hysterectomy for myomatous uteri.

STUDY DESIGN

In this retrospective cohort study of the first 50 consecutive patients with myomatous uteri undergoing a robotic hysterectomy, we report our experience with the EndoWrist(®) One™ Vessel Sealer (Intuitive Surgical Inc., Sunnyvale, CA) during this procedure. The learning curve was evaluated, and the operative times as well as the complications were recorded.

RESULTS

After the first 10 cases, the median console and total (skin-to-skin) operative time dropped significantly from 110 to 60min and from 158 to 105min, respectively (p=0.018 and p=0.008 respectively). The body mass index (≤ or >30kg/m(2)), uterine weight (≤ or >250g), and uterine size had no statistical significant effect on the total operative time. Median blood loss during surgery was 63mL in all cases (range: 0-400mL). The morbidity was low, and approximately 50% of cases could be discharged from the hospital after one to two days.

CONCLUSION

Robotic hysterectomy using the Vessel Sealer has, after a short learning curve of 10 cases, similar operative times than other published reports on robotic hysterectomy or laparoscopic hysterectomy using a sealing device for myomatous or large uteri.