Retrospective genetic testing (Traceback) in women with early-onset breast cancer after revised national guidelines: a clinical implementation study

PURPOSE

This study focused on identifying a hereditary predisposition in women previously diagnosed with early-onset breast cancer through a retrospective outreach activity (Traceback). The objectives were to evaluate the possible clinical implementation of a simplified Traceback strategy and to identify carriers of pathogenic variants among previously untested women.

METHODS

Three hundred and fifteen Traceback-eligible women diagnosed with breast cancer at 36-40 years in Southern Sweden between 2000 and 2019 were identified and offered an analysis of the genes ATM, BARD1, BRCA1, BRCA2, CHEK2, PALB2, RAD51C, and RAD51D through a standardized letter. Women who chose to participate were asked about their experiences through a questionnaire. The workload for the study personnel was measured and recorded.

RESULTS

One hundred and seventy-six women underwent genetic testing and pathogenic variants were identified in 9.7%: ATM (n = 6), BARD1 (n = 1), BRCA1 (n = 3), CHEK2 (n = 5), and PALB2 (n = 2). Women with normal test results were informed through a standardized letter. Carriers of pathogenic variants were contacted by telephone and offered in-person genetic counseling. One hundred and thirty-four women returned the subsequent questionnaire. Most study participants were satisfied with both written pre- and post-test information and many expressed their gratitude. The extra workload as compared to routine clinical genetic counseling was modest (8 min per patient).

CONCLUSION

The insights from the participants' perspectives and sentiments throughout the process support the notion that the Traceback procedure is a safe and an appreciated complement to routine genetic counseling. The genetic yield of almost 10% also suggests that the associated extra workload for genetic counselors could be viewed as acceptable in clinical implementation scenarios.

Longitudinal molecular profiling elucidates immunometabolism dynamics in breast cancer

Although metabolic reprogramming within tumor cells and tumor microenvironment (TME) is well described in breast cancer, little is known about how the interplay of immune state and cancer metabolism evolves during treatment. Here, we characterize the immunometabolic profiles of tumor tissue samples longitudinally collected from individuals with breast cancer before, during and after neoadjuvant chemotherapy (NAC) using proteomics, genomics and histopathology. We show that the pre-, on-treatment and dynamic changes of the immune state, tumor metabolic proteins and tumor cell gene expression profiling-based metabolic phenotype are associated with treatment response. Single-cell/nucleus RNA sequencing revealed distinct tumor and immune cell states in metabolism between cold and hot tumors. Potential drivers of NAC based on above analyses were validated in vitro. In summary, the study shows that the interaction of tumor-intrinsic metabolic states and TME is associated with treatment outcome, supporting the concept of targeting tumor metabolism for immunoregulation.

A prospective cohort study identifying radiologic and tumor related factors of importance for breast conserving surgery after neoadjuvant chemotherapy

INTRODUCTION

Neoadjuvant chemotherapy (NAC) is an established treatment option for early breast cancer, potentially downstaging the tumor and increasing the eligibility for breast-conserving surgery (BCS). The primary aim of this study was to assess the rate of BCS after NAC, and the secondary aim was to identify predictors of application of BCS after NAC.

MATERIALS AND METHODS

This was an observational prospective cohort study of 226 patients in the SCAN-B (Clinical Trials NCT02306096) neoadjuvant cohort during 2014-2019. Eligibility for BCS was assessed at baseline and after NAC. Uni- and multivariable logistic regression analyses were performed using covariates with clinical relevance and/or those associated with outcome (BCS versus mastectomy), including tumor subtype, by gene expression analysis.

RESULTS

The overall BCS rate was 52%, and this rate increased during the study period (from 37% to 52%). Pathological complete response was achieved in 69 patients (30%). Predictors for BCS were smaller tumor size on mammography, visibility on ultrasound, histological subtype other than lobular, benign axillary status, and a diagnosis of triple-negative or HER2-positive subtype, with a similar trend for gene expression subtypes. Mammographic density was negatively related to BCS in a dose-response pattern. In the multivariable logistic regression model, tumor stage at diagnosis and mammographic density showed the strongest association with BCS.

CONCLUSION

The rate of BCS after NAC increased during the study period to 52%. With modern treatment options for NAC the potential for tumor response and BCS eligibility might further increase.

Whole-body MRI surveillance in TP53 carriers is perceived as beneficial with no increase in cancer worry regardless of previous cancer: Data from the Swedish TP53 Study

BACKGROUND

To evaluate the psychosocial consequences of surveillance with whole-body MRI (WB-MRI) in individuals with the heritable TP53-related cancer (hTP53rc) syndrome, also known as the Li-Fraumeni syndrome, with regard to cancer worry, perceived benefits and risks to surveillance and overall health.

PATIENTS AND METHODS

Since 2016, the national Swedish TP53 Study (SWEP53) has offered surveillance with WB-MRI to all individuals with hTP53rc syndrome. Seventy-five individuals have been included in the study. Sixty consecutive participants fulfilled a base-line evaluation as well as an evaluation after 1 year with structured questionnaires including the Cancer Worry Scale (CWS), perceived benefits and risks of surveillance, and the 36-item Short Form Survey (SF-36). Individuals with or without previous personal cancer diagnosis were enrolled and results at baseline and after 1 year of surveillance were compared. For SF-36, a comparison with the normal population was also made.

RESULTS

Participants with previous cancer tend to worry more about cancer, but both individuals with and without cancer had a positive attitude toward surveillance with no differences regarding perceived benefits and barriers to surveillance. Participants with a previous cancer scored significantly lower on some of the SF-36 subscales, but between-group differences were found only for social functioning after 1 year.

CONCLUSIONS

Surveillance with WB-MRI is feasible from a psychosocial point of view both among TP53 carriers with as well as without a previous history of cancer and does not increase cancer worry in any of the groups.

PLAIN LANGUAGE SUMMARY

Individuals with heritable TP53-related cancer syndrome (also known as the Li-Fraumeni syndrome) have a high lifetime risk of developing cancer. These TP53 carriers are offered surveillance with whole-body MRI to detect cancer early. There are few reports of the psychosocial impact of surveillance. In this study, we wanted to evaluate cancer worry, benefits and barriers to participation, and perceived overall health. Our study shows no increase in cancer worry after 1 year of surveillance, regardless of previous cancer.

Abstract P1-09-06: Save the breast after neoadjuvant therapy – identifying radiological and tumor related factors of importance for breast conserving surgery after neoadjuvant chemotherapy

Background: Neoadjuvant chemotherapy (NAC) is an established treatment option in early breast cancer. NAC potentially downstages the tumor and, combined with oncoplastic techniques, may increase the eligibility for breast conserving surgery (BCS). NAC can also result in less surgical morbidity of the axilla if axillary clearance can be avoided. In addition, preoperative medical treatment allows for a thorough evaluation of treatment response and lays the foundation for adjuvant treatment decisions. The aim of the study was to prospectively estimate the proportion of BCS post NAC and the relation to well-defined factors associated with BCS post NAC.

Materials and methods: This observational prospective cohort study included 226 patients in the SCAN-B neoadjuvant cohort (Clinical trials: NCT02306096) receiving NAC between 2014 and 2019. Eligibility for BCS was based on the assessment of the surgeon at time of diagnosis and again post NAC. All the covariables were defined at time of diagnosis from mammograms and core needle biopsies, except for pathological complete response (pCR). Treatment generally consisted of 6 to 7 three-weekly treatment cycles of anthracycline- and taxane-based chemotherapy, given in sequence. In HER2-positive disease, HER2-directed antibodies were added as appropriate.The primary aim was to estimate the proportion of BCS after NAC and the secondary aim was to evaluate factors as predictors of BCS, including gene expression and surrogate molecular subtypes (St. Gallen), breast density, and other putative modifying factors.Uni- and multivariable logistic regression analysis were performed including covariates of clinical relevance and/or associated with the outcome measures (BCS versus mastectomy).

Results: The BCS rate increased during the study years, from 37% to 52%. pCR was achieved in 69 patients (30%). Predictors with a negative association to BCS were larger tumor size on mammography (T3 vs T1) (odds ratio (OR)=0.20, 95% confidence interval (CI) [0.06,0.64]), lack of visibility on ultrasound (OR=0.08, 95% CI [0.001,0.63]), lobular histological subtype vs other subtypes (OR=0,20, 95% CI [0.06,0.61)). Factors positively associated with BCS were benign axillary lymph node status (OR=2.26, 95% CI [1.26,4.06]) and surrogate molecular subtypes; patients with triple negative and HER-2 positive tumors had the highest probability of receiving BCS, 65% and 54%, respectively. Gene expression subtypes had a similar trend of being associated with BCS; patients with basal like and HER-2 enriched tumors had higher odds ratio for BCT than patients with luminal subtypes (Table 1). In the multivariable logistic regression analysis, tumor size on mammography and axillary status had the strongest association to BCS (OR=0.95, 95% CI [0.92,0.98] and OR=2.08, 95% CI [0.99,4.35], respectively).

Conclusions: Our study shows that the rate of BCS after NAC increased over the study years, but mastectomy rate in the study was still close to 50%. With increasing number of patients achieving pCR after NAC, the BCS rate should be possible to increase further. Predictors of BCS after NAC were identified, and benign axillary lymph nodes and smaller tumor size defined at time of diagnosis were the strongest predictors of BCS, supporting that initial tumor stage was important for the choice of surgery after NAC.

Table 1. Baseline characteristics and univariable logistic regression. 1. Determined by biopsy or sentinel node. 2. Only tumors visible on mammography. 3. Defined as ypT0/ypTis/ypN0.

Citation Format: Kim Gulis, Julia Ellbrant, Pär-Ola Bendahl, Tor Svensjö, Johan Vallon-Christersson, Ida Dalene Skarping, Niklas Loman, Lisa Rydén. Save the breast after neoadjuvant therapy – identifying radiological and tumor related factors of importance for breast conserving surgery after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-09-06.

Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high risk, early breast cancer

BACKGROUND

The randomized, double-blind OlympiA trial compared 1 year of the oral poly(adenosine diphosphate-ribose) polymerase inhibitor, olaparib, to matching placebo as adjuvant therapy for patients with pathogenic or likely pathogenic variants in germline BRCA1 or BRCA2 (gBRCA1/2pv) and high-risk, human epidermal growth factor receptor 2-negative, early breast cancer (EBC). The first pre-specified interim analysis (IA) previously demonstrated statistically significant improvement in invasive disease-free survival (IDFS) and distant disease-free survival (DDFS). The olaparib group had fewer deaths than the placebo group, but the difference did not reach statistical significance for overall survival (OS). We now report the pre-specified second IA of OS with updates of IDFS, DDFS, and safety.

PATIENTS AND METHODS

One thousand eight hundred and thirty-six patients were randomly assigned to olaparib or placebo following (neo)adjuvant chemotherapy, surgery, and radiation therapy if indicated. Endocrine therapy was given concurrently with study medication for hormone receptor-positive cancers. Statistical significance for OS at this IA required P < 0.015.

RESULTS

With a median follow-up of 3.5 years, the second IA of OS demonstrated significant improvement in the olaparib group relative to the placebo group [hazard ratio 0.68; 98.5% confidence interval (CI) 0.47-0.97; P = 0.009]. Four-year OS was 89.8% in the olaparib group and 86.4% in the placebo group (Δ 3.4%, 95% CI -0.1% to 6.8%). Four-year IDFS for the olaparib group versus placebo group was 82.7% versus 75.4% (Δ 7.3%, 95% CI 3.0% to 11.5%) and 4-year DDFS was 86.5% versus 79.1% (Δ 7.4%, 95% CI 3.6% to 11.3%), respectively. Subset analyses for OS, IDFS, and DDFS demonstrated benefit across major subgroups. No new safety signals were identified including no new cases of acute myeloid leukemia or myelodysplastic syndrome.

CONCLUSION

With 3.5 years of median follow-up, OlympiA demonstrates statistically significant improvement in OS with adjuvant olaparib compared with placebo for gBRCA1/2pv-associated EBC and maintained improvements in the previously reported, statistically significant endpoints of IDFS and DDFS with no new safety signals.

RNA sequencing-based single sample predictors of molecular subtype and risk of recurrence for clinical assessment of early-stage breast cancer

Multigene assays for molecular subtypes and biomarkers can aid management of early invasive breast cancer. Using RNA-sequencing we aimed to develop single-sample predictor (SSP) models for clinical markers, subtypes, and risk of recurrence (ROR). A cohort of 7743 patients was divided into training and test set. We trained SSPs for subtypes and ROR assigned by nearest-centroid (NC) methods and SSPs for biomarkers from histopathology. Classifications were compared with Prosigna in two external cohorts (ABiM, n = 100 and OSLO2-EMIT0, n = 103). Prognostic value was assessed using distant recurrence-free interval. Agreement between SSP and NC for PAM50 (five subtypes) was high (85%, Kappa = 0.78) for Subtype (four subtypes) very high (90%, Kappa = 0.84) and for ROR risk category high (84%, Kappa = 0.75, weighted Kappa = 0.90). Prognostic value was assessed as equivalent and clinically relevant. Agreement with histopathology was very high or high for receptor status, while moderate for Ki67 status and poor for Nottingham histological grade. SSP and Prosigna concordance was high for subtype (OSLO-EMIT0 83%, Kappa = 0.73 and ABiM 80%, Kappa = 0.72) and moderate and high for ROR risk category (68 and 84%, Kappa = 0.50 and 0.70, weighted Kappa = 0.70 and 0.78). Pooled concordance for emulated treatment recommendation dichotomized for chemotherapy was high (85%, Kappa = 0.66). Retrospective evaluation suggested that SSP application could change chemotherapy recommendations for up to 17% of postmenopausal ER+/HER2-/N0 patients with balanced escalation and de-escalation. Results suggest that NC and SSP models are interchangeable on a group-level and nearly so on a patient level and that SSP models can be derived to closely match clinical tests.

Abstract P2-08-11: How reliable are biomarkers assessed on a core needle biopsy? A study of paired core needle biopsies and surgical specimens in early breast cancer

Background: The conventional biomarkers estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), Ki67, and Nottingham histologic grade (NHG) are used to classify breast cancer into its molecular subtypes, determine prognosis, and guide treatment. A preoperative core needle biopsy (CNB) is used to confirm the diagnosis and invasiveness of a breast lesion and forms the basis for characterizing the tumor in the case of neoadjuvant primary treatment, emphasizing the importance of obtaining reliable biomarker assessment from a diagnostic CNB. Aim: The aim of this study was to determine the similarity between biomarker status assessed on a CNB compared to a medically untreated surgical specimen. Methods: Paired CNB and surgical specimens from 267 patients that were part of the prospective Sweden Cancerome Analysis Network- Breast (SCAN-B) cohort were studied. The concordance for the five biomarkers: ER, PgR, Ki67, HER2 and molecular subtype, between paired CNB and surgical specimen were investigated using immunohistochemistry (IHC) and gene expression-based analytical methods (GEX). IHC data were collected from patient medical records and gene expression was measured by RNA sequencing. Cohen’s kappa and Mcnemar’s test were used to compare the concordance of biomarkers.Results: Moderate to very good levels of concordance were observed between the biomarker status obtained on a CNB compared with the paired surgical specimen for IHC (κappa range 0.474-0.917) and GEX (κappa range 0.528-0.776), respectively. However, a significant drift from low to high Ki67 status and from negative to positive HER2 status between the CNB and surgical specimen was observed when using IHC and GEX, respectively (McNemar p &lt; 0.05 for both comparisons). Moderate to good concordance levels of biomarker status were generally obtained when comparing GEX and IHC status measured from the same type of sample (κappa range 0.484-0.649) except for Ki67 which consistently displayed poor concordance levels between IHC and GEX for both CNB and surgical specimen comparisons (κappa range 0.158-0.198). Notably, a significant shift from positive to negative ER status and high to low Ki67 status was observed when comparing IHC with GEX classification (McNemar p &lt;0.001 for both comparisons). Conclusion: The tissue sampling and the method of biomarker analysis may affect the results of biomarker status and ultimately affect treatment decisions. The implications of using a preoperative CNB to determine biomarker status, prognosis, and treatment choice should be taken into consideration in neoadjuvant treatment settings.

Citation Format: Hani Saghir, Srinivas Veerla, Martin Malmberg, Lisa Rydén, Anna Ehinger, Lao Saal, Johan Vallon-Christersson, Åke Borg, Cecilia Hegardt, Ingrid Hedenfalk, Susanne Dieroff-Hay, Christer Larsson, Niklas Loman, Siker Kimbung. How reliable are biomarkers assessed on a core needle biopsy? A study of paired core needle biopsies and surgical specimens in early breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-08-11.

Abstract OT2-30-01: Nordictrip, a translational randomized phase-3study exploring the effect of the addition of capecitabine to carboplatinum-based chemotherapy in early “triple negative” breast cancer, ClinicalTrials.gov Identifier: NCT04335669

Background: A striking heterogeneity combined with an absence of highly efficient targeted treatments necessitates a continued effort to optimize the choice of chemotherapy for patients with triple negative breast cancer (TNBC). Neoadjuvant therapy has become the standard of care for high risk TNBC in order to potentially reduce breast and axillary surgery, start medical treatment early, allow genomic screening and guide post neoadjuvant therapy. Much attention is drawn to the use of immunotherapy in early TNBC, but there is also interesting data suggesting a potential to optimize the use of conventional chemotherapy. According to one meta-analysis including data from nine randomized controlled trials, the addition of platinum salts in the preoperative setting increases the pathologic complete response (pCR) rate in TNBC (Poggio 2018). A second meta-analysis, evaluating the effect of capecitabine in early breast cancer indicates an additional benefit from adding capecitabine to conventional chemotherapy in terms of an increased recurrence-free survival in the subset of TNBC (Mackelenbergh SABCS 2019). An adjuvant trial in TNBC suggests that the beneficial effect of capecitabine may be confined to patients with a non-basal like phenotype of TNBC (Lluch 2020), a subset that correlates with the homologous repair non-deficient subset which constitutes 41 % of TNBC in a mainly south Swedish population based cohort (Staaf 2019). The effect of capecitabine in platinum treated early TNBC is unknown. Objectives: We are conducting a multi-center randomized controlled trial evaluating the effect on the pCR rate by the addition of capecitabine to optimal platinum based and dose dense preoperative chemotherapy in early TNBC. Method: 820 patients (pts) with early TNBC stage 1 (≥20 mm) - 3 will be randomized 1:1 between two treatment arms A and B. A: Epirubicine Cyclophosphamide (EC) q2w x 4 followed by Carboplatin AUC 5 q3w with weekly paclitaxel x 12. B: Epirubicine Cyclophosphamide with capecitabine daily for two weeks (CEX) q3w x 4 followed by Carboplatin AUC 5 q3w with weekly paclitaxel x 12 The primary endpoint is pCR rate in the different treatment strata, and the primary translational endpoint will be the potential difference of treatment effect stratified for HRD-status in the primary tumor. Secondary endpoints include IDFS in subsets of TNBC, eg according to gene-expression-based subtypes of TNBC (Lehmann 2011, Burstein 2015), and germline mutation status of hereditary breast cancer genes. Tumor material for genotypig is collected at baseline, at surgery and optionally after two treatment cycles. Sequential blood samples are collected for tsDNA analysis during and after treatment termination. Results: The trial, which is a collaborative effort between the national breast cancer groups in the participating countries, has been postponed by the pandemic but is now recruiting according to plan. So far 56 patients out of 820 have been recruited at 15 sites in Sweden and Denmark. Additional Sites in Sweden, Denmark, Iceland and Finland are preparing to join the study. For update please see: www.NordicTrip.se; E-mail address: Nordictrip.onkologi@skane.se

Citation Format: Niklas Loman, Barbro Linderholm, Johan Ahlgren, Siker Kimbung, Lina Zander, Heidi Grill Magnusson, Eva-Christin Kjellman, Ann Julia Raaberg, Maj-Britt Raaby Jensen, Åke Borg, Johan Staaf, Anders Ståhlberg, Pär-Ola Bendahl, Anne-Vibeke Laenkholm, Minna Tanner, Olöf Bjarnadóttir, Oskar Johannsson, Bent Ejlertsen, Henrik Lindman. Nordictrip, a translational randomized phase-3study exploring the effect of the addition of capecitabine to carboplatinum-based chemotherapy in early “triple negative” breast cancer, ClinicalTrials.gov Identifier: NCT04335669 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-30-01.

Preexisting Somatic Mutations of Estrogen Receptor Alpha (ESR1) in Early-Stage Primary Breast Cancer

Background

More than three-quarters of primary breast cancers are positive for estrogen receptor alpha (ER; encoded by the gene ESR1), the most important factor for directing anti-estrogenic endocrine therapy (ET). Recently, mutations in ESR1 were identified as acquired mechanisms of resistance to ET, found in 12% to 55% of metastatic breast cancers treated previously with ET.

Methods

We analyzed 3217 population-based invasive primary (nonmetastatic) breast cancers (within the SCAN-B study, ClinicalTrials.gov NCT02306096), sampled from initial diagnosis prior to any treatment, for the presence of ESR1 mutations using RNA sequencing. Mutations were verified by droplet digital polymerase chain reaction on tumor and normal DNA. Patient outcomes were analyzed using Kaplan-Meier estimation and a series of 2-factor Cox regression multivariable analyses.

Results

We identified ESR1 resistance mutations in 30 tumors (0.9%), of which 29 were ER positive (1.1%). In ET-treated disease, presence of ESR1 mutation was associated with poor relapse-free survival and overall survival (2-sided log-rank test P < .001 and P = .008, respectively), with hazard ratios of 3.00 (95% confidence interval = 1.56 to 5.88) and 2.51 (95% confidence interval = 1.24 to 5.07), respectively, which remained statistically significant when adjusted for other prognostic factors.

Conclusions

These population-based results indicate that ESR1 mutations at diagnosis of primary breast cancer occur in about 1% of women and identify for the first time in the adjuvant setting that such preexisting mutations are associated to eventual resistance to standard hormone therapy. If replicated, tumor ESR1 screening should be considered in ER-positive primary breast cancer, and for patients with mutated disease, ER degraders such as fulvestrant or other therapeutic options may be considered as more appropriate.

Prognostic role of serum thymidine kinase 1 kinetics during neoadjuvant chemotherapy for early breast cancer

Background

Emerging data support the use of thymidine kinase 1 (TK1) activity as a prognostic marker and for monitoring of response in breast cancer (BC). The long-term prognostic value of TK1 kinetics during neoadjuvant chemotherapy is unclear, which this study aimed to elucidate.

Methods

Material from patients enrolled to the single-arm prospective PROMIX trial of neoadjuvant epirubicin, docetaxel and bevacizumab for early BC was used. Ki67 in baseline biopsies was assessed both centrally and by automated digital imaging analysis. TK1 activity was measured from blood samples obtained at baseline and following two cycles of chemotherapy. The associations of TK1 and its kinetics as well as Ki67 with event-free survival and overall survival (OS) were evaluated using multivariable Cox regression models.

Results

Central Ki67 counting had excellent correlation with the results of digital image analysis (r = 0.814), but not with the diagnostic samples (r = 0.234), while it was independently prognostic for worse OS [adjusted hazard ratio (HR_adj) = 2.72, 95% confidence interval (CI) 1.19-6.21, P = 0.02]. Greater increase in TK1 activity after two cycles of chemotherapy resulted in improved event-free survival (HR_adj = 0.50, 95% CI 0.26-0.97, P = 0.04) and OS (HR_adj = 0.46, 95% CI 0.95, P = 0.04). There was significant interaction between the prognostic value of TK1 kinetics and Ki67 (p_interaction 0.04).

Conclusion

Serial measurement of serum TK1 activity during neoadjuvant chemotherapy provides long-term prognostic information in BC patients. The ease of obtaining serial samples for TK1 assessment motivates further evaluation in larger studies.

•

This is a correlative analysis of a prospective phase II study on neoadjuvant chemotherapy for breast cancer.

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Serial measurement of serum TK1 activity during treatment provides independent long-term prognostic information.

•

We demonstrate the validity and clinical utility of both central and automated image analysis-based Ki67 assessment.

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Finally, we explore the biologic correlations between TK1 and Ki67.

Protein Signature Predicts Response to Neoadjuvant Treatment With Chemotherapy and Bevacizumab in HER2-Negative Breast Cancers

PURPOSE

Antiangiogenic therapy using bevacizumab has proven effective for a number of cancers; however, in breast cancer (BC), there is an unmet need to identify patients who benefit from such treatment.

PATIENTS AND METHODS

In the NeoAva phase II clinical trial, patients (N = 132) with large (≥ 25 mm) human epidermal growth factor receptor 2 (HER2)-negative primary tumors were randomly assigned 1:1 to treatment with neoadjuvant chemotherapy (CTx) alone or in combination with bevacizumab (Bev plus CTx). The ratio of the tumor size after relative to before treatment was calculated into a continuous response scale. Tumor biopsies taken prior to neoadjuvant treatment were analyzed by reverse-phase protein arrays (RPPA) for expression levels of 210 BC-relevant (phospho-) proteins. Lasso regression was used to derive a predictor of tumor shrinkage from the expression of selected proteins prior to treatment.

RESULTS

We identified a nine-protein signature score named vascular endothelial growth factor inhibition response predictor (ViRP) for use in the Bev plus CTx treatment arm able to predict with accuracy pathologic complete response (pCR) (area under the curve [AUC] = 0.85; 95% CI, 0.74 to 0.97) and low residual cancer burden (RCB 0/I) (AUC = 0.80; 95% CI, 0.68 to 0.93). The ViRP score was significantly lower in patients with pCR (P < .001) and in patients with low RCB (P < .001). The ViRP score was internally validated on mRNA data and the resultant surrogate mRNA ViRP score significantly separated the pCR patients (P = .016). Similarly, the mRNA ViRP score was validated (P < .001) in an independent phase II clinical trial (PROMIX).

CONCLUSION

Our ViRP score, integrating the expression of nine proteins and validated on mRNA data both internally and in an independent clinical trial, may be used to increase the likelihood of benefit from treatment with bevacizumab combined with chemotherapy in patients with HER2-negative BC.

Human G-MDSCs are neutrophils at distinct maturation stages promoting tumor growth in breast cancer

This study shows that immunosuppressive primary breast cancer patient–derived G-MDSCs (PMN-MDSCs) are neutrophils at a range of maturations stages, and provides in vivo evidence for that human G-MDSCs also promote tumor growth and myeloid immune cell exclusion.

Myeloid-derived suppressor cells (MDSCs) are known to contribute to immune evasion in cancer. However, the function of the human granulocytic (G)-MDSC subset during tumor progression is largely unknown, and there are no established markers for their identification in human tumor specimens. Using gene expression profiling, mass cytometry, and tumor microarrays, we here demonstrate that human G-MDSCs occur as neutrophils at distinct maturation stages, with a disease-specific profile. G-MDSCs derived from patients with metastatic breast cancer and malignant melanoma display a unique immature neutrophil profile, that is more similar to healthy donor neutrophils than to G-MDSCs from sepsis patients. Finally, we show that primary G-MDSCs from metastatic breast cancer patients co-transplanted with breast cancer cells, promote tumor growth, and affect vessel formation, leading to myeloid immune cell exclusion. Our findings reveal a role for human G-MDSC in tumor progression and have clinical implications also for targeted immunotherapy.

Breast cancer survival in Nordic BRCA2 mutation carriers-unconventional association with oestrogen receptor status

Background

The natural history of breast cancer among BRCA2 carriers has not been clearly established. In a previous study from Iceland, positive ER status was a negative prognostic factor. We sought to identify factors that predicted survival after invasive breast cancer in an expanded cohort of BRCA2 carriers.

Methods

We studied 608 women with invasive breast cancer and a pathogenic BRCA2 mutation (variant) from four Nordic countries. Information on prognostic factors and treatment was retrieved from health records and by analysis of archived tissue specimens. Hazard ratios (HR) were estimated for breast cancer-specific survival using Cox regression.

Results

About 77% of cancers were ER-positive, with the highest proportion (83%) in patients under 40 years. ER-positive breast cancers were more likely to be node-positive (59%) than ER-negative cancers (34%) (P < 0.001). The survival analysis included 584 patients. Positive ER status was protective in the first 5 years from diagnosis (multivariate HR = 0.49; 95% CI 0.26–0.93, P = 0.03); thereafter, the effect was adverse (HR = 1.91; 95% CI 1.07–3.39, P = 0.03). The adverse effect of positive ER status was limited to women who did not undergo endocrine treatment (HR = 2.36; 95% CI 1.26–4.44, P = 0.01) and patients with intact ovaries (HR = 1.99; 95% CI 1.11–3.59, P = 0.02).

Conclusions

The adverse effect of a positive ER status in BRCA2 carriers with breast cancer may be contingent on exposure to ovarian hormones.

The mutational landscape of the SCAN-B real-world primary breast cancer transcriptome

Breast cancer is a disease of genomic alterations, of which the panorama of somatic mutations and how these relate to subtypes and therapy response is incompletely understood. Within SCAN‐B (ClinicalTrials.gov: NCT02306096), a prospective study elucidating the transcriptomic profiles for thousands of breast cancers, we developed a RNA‐seq pipeline for detection of SNVs/indels and profiled a real‐world cohort of 3,217 breast tumors. We describe the mutational landscape of primary breast cancer viewed through the transcriptome of a large population‐based cohort and relate it to patient survival. We demonstrate that RNA‐seq can be used to call mutations in genes such as PIK3CA,TP53, and ERBB2, as well as the status of molecular pathways and mutational burden, and identify potentially druggable mutations in 86.8% of tumors. To make this rich dataset available for the research community, we developed an open source web application, the SCAN‐B MutationExplorer (http://oncogenomics.bmc.lu.se/MutationExplorer). These results add another dimension to the use of RNA‐seq as a clinical tool, where both gene expression‐ and mutation‐based biomarkers can be interrogated in real‐time within 1 week of tumor sampling.

Abstract CT074: Pre-existing ESR1 mutations in early-stage primary breast cancer predict failure of endocrine therapy and poor survival

Background: More than three-quarters of primary breast cancers are positive for estrogen receptor alpha (ER; encoded by the gene ESR1), the most important factor for directing anti-estrogenic endocrine therapy. Although mutation in ESR1 is known as an acquired mechanism of resistance to endocrine therapy (ET), found in 12-55% of metastatic breast cancers treated previously with ET, the impact of ESR1 mutation on therapy response in primary breast cancer is unclear. Patients and methods: In this study we analyzed 3217 real-world and population-based early-stage primary breast cancers (within the SCAN-B study, ClinicalTrials.gov NCT02306096). Tissues were sampled from initial diagnosis prior to any treatment and analyzed for the presence of ESR1 mutations using RNA sequencing. Mutations were verified by SAGAsafe droplet digital PCR. Results: We identified ESR1 resistance mutations in 30 cases (0.9%), of which 29 were ER-positive (1.1%). In ER-positive disease, presence of ESR1 mutation was significantly associated to poor relapse-free survival (RFS) and overall survival (OS) (p=0.011 and p=0.019, respectively), and moreover predicted poor RFS and OS within the patient group that received ET (p=0.007 and p=0.010, respectively). Conclusions: These results indicate that ESR1 mutations at diagnosis of untreated primary breast cancer are rare, however we confirm for the first time that such early mutations predict eventual resistance to standard hormone therapy in the adjuvant setting. If replicated, tumor ESR1 screening may be considered in ER-positive primary breast cancer and, in mutated cases, ER-degraders such as fulvestrant or other therapeutic options may be considered as more appropriate.

Citation Format: Malin Dahlgren, Anthony M. George, Christian Brueffer, Sergii Gladchuk, Yilun Chen, Johan Vallon-Christersson, Cecilia Hegardt, Jari Häkkinen, Lisa Rydén, Martin Malmberg, Christer Larsson, Sofia K. Gruvberger-Saal, Anna Ehinger, Niklas Loman, Åke Borg, Lao H. Saal. Pre-existing ESR1 mutations in early-stage primary breast cancer predict failure of endocrine therapy and poor survival [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT074.

Comprehensive molecular comparison of BRCA1 hypermethylated and BRCA1 mutated triple negative breast cancers

Homologous recombination deficiency (HRD) is a defining characteristic in BRCA-deficient breast tumors caused by genetic or epigenetic alterations in key pathway genes. We investigated the frequency of BRCA1 promoter hypermethylation in 237 triple-negative breast cancers (TNBCs) from a population-based study using reported whole genome and RNA sequencing data, complemented with analyses of genetic, epigenetic, transcriptomic and immune infiltration phenotypes. We demonstrate that BRCA1 promoter hypermethylation is twice as frequent as BRCA1 pathogenic variants in early-stage TNBC and that hypermethylated and mutated cases have similarly improved prognosis after adjuvant chemotherapy. BRCA1 hypermethylation confers an HRD, immune cell type, genome-wide DNA methylation, and transcriptional phenotype similar to TNBC tumors with BRCA1-inactivating variants, and it can be observed in matched peripheral blood of patients with tumor hypermethylation. Hypermethylation may be an early event in tumor development that progress along a common pathway with BRCA1-mutated disease, representing a promising DNA-based biomarker for early-stage TNBC.

Prognostic implications of the expression levels of different immunoglobulin heavy chain-encoding RNAs in early breast cancer

The extent and composition of the immune response in a breast cancer is one important prognostic factor for the disease. The aim of the current work was to refine the analysis of the humoral component of an immune response in breast tumors by quantifying mRNA expression of different immunoglobulin classes and study their association with prognosis. We used RNA-Seq data from two local population-based breast cancer cohorts to determine the expression of IGJ and immunoglobulin heavy (IGH) chain-encoding RNAs. The association with prognosis was investigated and public data sets were used to corroborate the findings. Except for IGHE and IGHD, mRNAs encoding heavy chains were generally detected at substantial levels and correlated with other immune-related genes. High IGHG1 mRNA was associated with factors related to poor prognosis such as estrogen receptor negativity, HER2 amplification, and high grade, whereas high IGHA2 mRNA levels were primarily associated with lower age at diagnosis. High IGHA2 and IGJ mRNA levels were associated with a more favorable prognosis both in univariable and multivariable Cox models. When adjusting for other prognostic factors, high IGHG1 mRNA levels were positively associated with improved prognosis. To our knowledge, these results are the first to demonstrate that expression of individual Ig class types has prognostic implications in breast cancer.

Defining the mutational landscape of 3,217 primary breast cancer transcriptomes through large-scale RNA-seq within the Sweden Cancerome Analysis Network: Breast Project (SCAN-B; NCT03430492)

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Background: Breast cancer is a disease of genomic alterations, of which the complete panorama of somatic mutations and how these relate to molecular subtypes and therapy response is incompletely understood. The Sweden Cancerome Analysis Network-Breast project (SCAN-B; ClinicalTrials.gov NCT02306096) is a multi-center population-based ongoing prospective observational study elucidating the global transcriptomic profiles for thousands of patients and tumors using RNA sequencing. Since September 2010, over 15,000 patients with breast cancer have been enrolled at 9 hospitals across a wide geography of Sweden, comprising greater than 90% of all eligible patients in the catchment area. Methods: Within SCAN-B, we developed an optimized bioinformatics pipeline for detection of single nucleotide variants and small insertions and deletions from RNA-seq data. From this, we describe the mutational landscape of 3,217 primary breast cancer transcriptomes, and relate it to patient overall survival in a real-world setting (median follow-up 75 months, range 2-105 months). Results: We demonstrate that RNA-seq can be used to call mutations in important breast cancer genes such as PIK3CA, TP53, ESR1, and ERBB2, as well as mutation status of key molecular pathways and tumor mutational burden, identify mutations in one or more potentially druggable genes in 85.3% percent of cases, and reveal significant relationships to patient outcome within specific treatment groups. To make this rich and growing mutational portraiture of breast cancer available for the wider research community, we developed an open source interactive web application, SCAN-B MutationExplorer, publicly accessible at http://oncogenomics.bmc.lu.se/MutationExplorer . Conclusions: These results add another dimension to the use of RNA-seq as a potential clinical tool, where both gene expression-based signatures and gene mutation-based biomarkers can be interrogated simultaneously and in real-time within one week of tumor sampling.

Abstract A73: Human granulocytic myeloid-derived suppressor cells (G-MDSCs) in metastatic breast cancer patients is a heterogeneous population with angiogenic potential in vivo

MDSCs are potent immunosuppressive myeloid cells that have been implicated in various diseases, including cancer. In humans, MDSCs are divided into Mo-GMDSCs and G-MDSCs subgroups, depending on their surface phenotype and function. While their immunosuppressive properties have been extensively studied, knowledge about their origin and their tumor-promoting functions per se remains scarce. In this study, we demonstrate that G-MDSCs are significantly enriched in the peripheral blood of locoregional recurrent metastatic breast cancer (LRR/MBC) compared to healthy donors. The G-MDSCs display a heterogeneous population with a morphology representing one blast-like and one polymorphonuclear (PMN) population. In a breast cancer xenograft model, co-transplanting G-MDSCs sorted from LRR/MBC together with breast cancer cells significantly promoted angiogenesis and tumor growth. Gene expression profiling analysis revealed that G-MDSCs from LRR/MBC rather clustered with neutrophils from healthy donors, sharing similar expression in genes relevant for angiogenesis, lymphangiogenesis and immunosuppression, but surprisingly not with G-MDSCs from sepsis patients. We conclude that enrichment of G-MDSCs in metastatic breast cancer represents a heterogeneous population of activated neutrophils that can promote angiogenesis and tumor progression, and immature blasts of yet unknown character.

Citation Format: Meliha Mehmeti, Caroline Bergenfelz, Daniel Bexell, Robert Carlsson, Rebecka Hellsten, Anna-Maria Larsson, Niklas Loman, Kristian Riesbeck, Jonas Ahl, Camilla Rydberg-Millrud, Gesine Paul-Visse, Lisa Rydén, Fredrika Killander, Karin Leandersson. Human granulocytic myeloid-derived suppressor cells (G-MDSCs) in metastatic breast cancer patients is a heterogeneous population with angiogenic potential in vivo [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A73.

Abstract P1-18-10: Preoperative treatment of HER2-positive breast cancer in South Sweden. A retrospective, comprehensive survey of neo-adjuvant treated HER2-positve breast cancer in the SCAN-B project 2010-2017

Introduction: Over the last few years, neoadjuvant therapy has become a standard of care in HER2-positive early breast cancer. This standard has recently been confirmed by the St. Gallen Consensus for stage II and III HER2-positive disease. In neoadjuvant treatment adding anti HER2 treatment almost doubled the pathological complete response (pCR) rate. Later studies have shown a better outcome for patients achieving a pCR compared with those with a non-pCR. The aim of this study is to present a comprehensive description of preoperative treatment in HER2-positive, according to ASCO and Swedish guidelines, breast cancer with detail treatment routines, choice of drugs and regimens as well as adherence to national guidelines and treatment changes over time.

Material: During the period October 2010 to December 2017 6572 patients with early breast cancer were diagnosed in the Skåne region of South Sweden and included in the SCAN-B project (Sweden Cancerome Analysis Network - Breast project, ClinicalTrials.gov identifier NCT02306096). The SCAN-B project is a population based study that during the period included 76.7% of all primary breast cancer patients in the catchment area. The majority of all tumors have been analyzed by NGS-based RNA sequencing, RNAseq.

Results: Of the 6572 patients 672 (10.2%) were HER2 positive and of these 101 (15%) were treated in a neoadjuvant setting with chemotherapy and HER2 directed antibodies. The proportion of HER2-positive patients receiving neoadjuvant treatment with trastuzumab increased from 9% in 2010 to 29% in 2017. Patient age was 27 to 89 years, median age 54 years. Pertuzumab was introduced in 2016 and in 2017 85% of patients received the combination of trastuzumab and pertuzumab. At diagnosis tumor stage T1, T2, T3 and T4d was 19%, 60%, 14% and 5% respectively and 50% were node negative at sentinel node biopsy pre treatment. Of tumors 52% were estrogen receptor positive (ie &gt;10% stained nuclei). During the neoadjuvant treatment period 31 patients were hospitalized at median 2 times for toxicity and a total of medium 4.7 days. At surgery 62% had a mastectomy and 38% breast conserving surgery. Follow up time is median 3.9 years and overall survival 94%.

Conclusions: This retrospective analysis of neoadjuvant treated HER2-positive breast cancer patients shows a gradual increase of neoadjuvant treatment and a very fast implementation of pertuzumab when it became available in Sweden. Overall survival is high but the follow up time is short and the material to small to analyze subgroups. Data on tumor RNAseq will be presented.

Citation Format: Martin Malmberg, Christer Larsson, Johan Vallon-Christersson, Anna Ehinger, Cecilia Hegardt, Fredrika Killander, Lisa Ryden, Lao H. Saal, Niklas Loman, Åke Borg. Preoperative treatment of HER2-positive breast cancer in South Sweden. A retrospective, comprehensive survey of neo-adjuvant treated HER2-positve breast cancer in the SCAN-B project 2010-2017 [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 P1-18-10.

Agreement between molecular subtyping and surrogate subtype classification: a contemporary population-based study of ER-positive/HER2-negative primary breast cancer

PURPOSE

Oestrogen receptor-positive (ER+) and human epidermal receptor 2-negative (HER2-) breast cancers are classified as Luminal A or B based on gene expression, but immunohistochemical markers are used for surrogate subtyping. The aims of this study were to examine the agreement between molecular subtyping (MS) and surrogate subtyping and to identify subgroups consisting mainly of Luminal A or B tumours.

METHODS

The cohort consisted of 2063 patients diagnosed between 2013-2017, with primary ER+/HER2- breast cancer, analysed by RNA sequencing. Surrogate subtyping was performed according to three algorithms (St. Gallen 2013, Maisonneuve and our proposed Grade-based classification). Agreement (%) and kappa statistics (κ) were used as concordance measures and ROC analysis for luminal distinction. Ki67, progesterone receptor (PR) and histological grade (HG) were further investigated as surrogate markers.

RESULTS

The agreement rates between the MS and St. Gallen 2013, Maisonneuve and Grade-based classifications were 62% (κ = 0.30), 66% (κ = 0.35) and 70% (κ = 0.41), respectively. PR did not contribute to distinguishing Luminal A from B tumours (auROC = 0.56). By classifying HG1-2 tumours as Luminal A-like and HG3 as Luminal B-like, agreement with MS was 80% (κ = 0.46). Moreover, by combining HG and Ki67 status, a large subgroup of patients (51% of the cohort) having > 90% Luminal A tumours could be identified.

CONCLUSIONS

Agreement between MS and surrogate classifications was generally poor. However, a post hoc analysis showed that a combination of HG and Ki67 could identify patients very likely to have Luminal A tumours according to MS.