Abstract ES7-1: Challenges in the management of locoregional recurrence

The increasing trend toward tailoring treatment of the primary breast cancer with limited surgery of both the breast and axilla has increased the challenge of managing locoregional recurrence (LRR). In the era when patients uniformly had axillary dissection, the appropriateness of repeat sentinel node biopsy was not a question. Similarly, the dogma that all ipsilateral breast tumor recurrences must be treated with mastectomy if the breast has been previously irradiated is also being challenged. LRR events are infrequent with modern multi-modality therapy, and there are no randomized trials to address these questions.

Re-operative sentinel node (SN) biopsy after breast conserving surgery therapy (BCT) has been shown to be feasible, with the likelihood of identifying additional SNs related to the number of nodes excised at the time of initial SN biopsy. The accuracy of SN biopsy after mastectomy is less clear. However, the impact of identification of nodal disease on management of LRR is controversial. In a study of 12 patients with isolated chest wall recurrence post mastectomy, 10/12 had successful mapping and 7/10 had an axillary SN. The absence of nodal metastases was an indication to avoid supraclavicular RT (Johnson J. Ann Surg Oncol 2016;23:715). In a study of 83 patients with in breast (n=79) or chest wall recurrence who were clinically node negative, 47 had axillary surgery and 36 did not. At a median of 4.2 years after LR, rates of axillary and non-axillary local recurrence, distant metastases, and death did not differ significantly between groups (Ugras S. Ann Surg Oncol 2016). With the findings of the CALOR trial that systemic chemotherapy is beneficial in the management of LRR, the finding of axillary metastases is less likely to influence systemic therapy than in the past and repeat axillary staging could potentially be avoided.

In the untreated breast, drainage to the contralateral axilla is very rare and contralateral axillary metastases classify a patient as Stage IV. After initial axillary dissection, between 4% and 33% of patients with local recurrence will have contralateral axillary drainage. In a systemic review of 48 cases of contralateral nodal recurrence without other distant metastatic disease, at a mean follow-up of 50.3 months disease free survival was 65% and overall survival 83% after treatment that included both local and systemic therapy (Moossdorff M. Eur J Surg Oncol 2015;41:1128). These findings raise the possibility that in the setting of LR, contralateral axillary metastases should be treated aggressively for cure after excluding distant metastases.

Citation Format: Morrow M. Challenges in the management of locoregional recurrence [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 ES7-1.

Abstract P2-12-03: Impact of the SSO-ASTRO consensus guidelines on invasive margins on the re-excision rate among patients undergoing breast conserving surgery (BCS)

Background: BCS has been historically associated with a high re-excision rate, driven in part by lack of consensus on what constitutes an adequate negative margin. The SSO-ASTRO consensus guideline on invasive margins defined a negative margin as no ink on tumor based on evidence suggesting that more widely clear margins do not further decrease the risk of recurrence, potentially reducing the need for re-excision. In a large nationwide cohort of breast cancer patients undergoing BCS for invasive breast cancer we evaluate the rates of re-excision following BCS before and after the SSO-ASTRO consensus guidelines were disseminated.

Methods: Breast cancer patients undergoing BCS for invasive breast cancer between January 2012 and December 2015 were identified among female beneficiaries in the MarketScan database. Patients receiving chemotherapy before surgery were excluded. Based upon presentation of the guideline recommendations in October 2013, the pre-guideline period was defined from January 2012 to September 2013. On-line publication of the guideline in February 2014 led to definition of the post-guideline period from March 2014 onwards. The peri-guideline period was defined as the time between the pre and post-guideline intervals. Any re-excision or mastectomy within 3 months of initial BCS was identified using ICD-9 or CPT codes. Overall re-excision rates and 95% CI were calculated; groups were compared using X2test. We used a regression model to evaluate the association between pre-peri-post guideline period and re-excision while adjusting for important covariates. Results are expressed as risk ratios (RRs) and 95%CI.

Results: A total of 38,573 patients were included (20,159 in the pre-guideline, 4,607 peri-guideline and 13,807 post-guideline). The overall re-excision rate was 23.9% (95%CI 23.4-24.3). The pre-guideline re-excision rate was 25.3% (95%CI 24.7-29.9) compared to 21.6% (95%CI 20.9-22.3] in the post-guideline period. (p<0.001). The rate of mastectomy as the final surgical procedure was 20.2% in the pre-guideline period and 19.1% in the post-guideline (p=0.15). We observed significant geographic variability by state in the decrease of the re-excision rates. No change in re-excision rates was seen in Mississippi, Vermont, Georgia, Oregon, West Virginia, Arkansas, Oklahoma and Tennessee. An absolute decrease greater than 10% in the re-excision rate was observed in Indiana, Nebraska, Alabama, Maine and Nevada. In the multivariable analysis, patients undergoing BCS in the post-guideline period had a statistically significant decrease in the risk of re-excision compared to patients undergoing surgery in the pre-guideline period (RR=0.87; 95%CI 0.84-0.91; p<0.001).

Conclusions: There has been a statistically significant decrease in the re-excision rate after BCS associated with the time of the dissemination of the SSO-ASTRO consensus guideline on invasive margins. The wide geographical variation observed suggests differences in the adoption rates. Our study confirms the impact that guidelines have modifying patterns of practice, reducing the frequency of unnecessary surgical interventions.

Citation Format: Chavez-MacGregor M, Lei X, Morrow M, Giordano SH. Impact of the SSO-ASTRO consensus guidelines on invasive margins on the re-excision rate among patients undergoing breast conserving surgery (BCS) [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 P2-12-03.

De-escalating and escalating treatments for early-stage breast cancer: the St. Gallen International Expert Consensus Conference on the Primary Therapy of Early Breast Cancer 2017

The 15th St. Gallen International Breast Cancer Conference 2017 in Vienna, Austria reviewed substantial new evidence on loco-regional and systemic therapies for early breast cancer. Treatments were assessed in light of their intensity, duration and side-effects, seeking where appropriate to escalate or de-escalate therapies based on likely benefits as predicted by tumor stage and tumor biology. The Panel favored several interventions that may reduce surgical morbidity, including acceptance of 2 mm margins for DCIS, the resection of residual cancer (but not baseline extent of cancer) in women undergoing neoadjuvant therapy, acceptance of sentinel node biopsy following neoadjuvant treatment of many patients, and the preference for neoadjuvant therapy in HER2 positive and triple-negative, stage II and III breast cancer. The Panel favored escalating radiation therapy with regional nodal irradiation in high-risk patients, while encouraging omission of boost in low-risk patients. The Panel endorsed gene expression signatures that permit avoidance of chemotherapy in many patients with ER positive breast cancer. For women with higher risk tumors, the Panel escalated recommendations for adjuvant endocrine treatment to include ovarian suppression in premenopausal women, and extended therapy for postmenopausal women. However, low-risk patients can avoid these treatments. Finally, the Panel recommended bisphosphonate use in postmenopausal women to prevent breast cancer recurrence. The Panel recognized that recommendations are not intended for all patients, but rather to address the clinical needs of the majority of common presentations. Individualization of adjuvant therapy means adjusting to the tumor characteristics, patient comorbidities and preferences, and managing constraints of treatment cost and access that may affect care in both the developed and developing world.

Abstract P2-02-06: Genetic counseling, germline genetic testing, and impact of results in patients with newly diagnosed breast cancer

The surge in BRCA1/2 and multiple-gene panel testing after a diagnosis of breast cancer has fueled concerns about how genetic testing results will be integrated into patient management. However, there is virtually no research about the timing or extent of genetic counseling before or after testing or the impact of genetic results on bilateral mastectomy (BLM) use since the advent of more widespread testing.

Methods: A population-based sample of 3600 patients newly diagnosed with breast cancer identified by two SEER registries (Georgia and Los Angeles County) were sent surveys two months after surgery (Dx dates 2014-15) about their genetic testing and treatment experiences. Survey information was merged with SEER data. We examined patterns and correlates of counseling and genetic testing and the impact of results on patient preferences for BLM and receipt of BLM.

Results: Among 2388 patients with unilateral breast cancer (response 70%), 697 (29.2%) had elevated pre-test risk of a germline mutation (based on age, family cancer history, ancestry, and tumor subtype). One-quarter of these higher risk patients (25.6%) did not discuss whether to have testing with any provider, 26.1% discussed it with clinicians only, and 48.3% had a visit with a genetic counselor. Half of patients with elevated pre-test risk (51.2%) were tested: 6.6% before diagnosis, 65.4% after diagnosis but before surgery and 28.0% after surgery. Higher risk patients who underwent testing were younger (p<.001) and had higher income (p=.029) but rates did not differ significantly by race, education, insurance, marital status, cancer stage, comorbidities, or geographic site after controlling for all covariates. There was wide variation in the type of professional who discussed test results with patients: discussed with surgeon only (17.8%), medical oncologist only (19.7%), both physicians but no counselor (4.8%), or genetic counselors (56.8%). Among all testers in the total sample (n=667), 54 (9.4%) reported a pathogenic mutation (12.1% of higher risk patients vs 5.7% of low risk patients) and 59 (10.0%) reported a variant of unknown significance (VUS) (10.2% of higher risk patients vs 9.9% of lower risk patients), p=.027 for differences between groups. Two-thirds (60.4%) of patients with pathogenic mutations reported that the test made them more interested in BLM vs 8.8% of those with a VUS, and 11.4% of those with negative tests, p<.001. Two-thirds (69.2%) of those with pathogenic mutations received BLM vs 21.9% of those with VUS and 27.9% of those with negative tests, p<.001.

Conclusions: Many patients newly diagnosed with breast cancer at higher risk of carrying a pathogenic mutation do not receive pre-test counseling or genetic testing and disparities are observed. There is wide variability in the timing of genetic testing after diagnosis and with which clinician the findings are discussed. Taken together, these results suggest that germline genetic testing after a diagnosis of breast cancer is poorly integrated into practice. However, the impact of genetic test results on patient attitudes and receipt of bilateral mastectomy suggests that genetic testing does help target prevention to a patient's future risk for a new primary breast cancer.

Citation Format: Katz SJ, Morrow M, Jagsi R, Kurian A. Genetic counseling, germline genetic testing, and impact of results in patients with newly diagnosed breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-02-06.

Abstract PD5-05: Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index

Background: Elevated body mass index (BMI) is associated with increased risk of postmenopausal breast cancer, which may be partly attributable to an inflammation-aromatase axis. Most individuals with elevated BMI harbor white adipose tissue inflammation (WATi), defined by the presence of crown-like structures in the breast (CLS-B). CLS-B are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. This inflammation is associated with activation of NF-κB and elevated expression of aromatase, which could contribute to tumor development. Additionally, WATi correlates with several circulating changes, including hyperinsulinemia, which increase breast cancer risk. Although breast WATi correlates with rising BMI, it is also present in some normal BMI individuals. Beyond inherited germline syndromes, the etiology of breast cancer in individuals with normal BMI is not well understood. Here we examined the impact of breast WATi on breast aromatase expression and circulating factors in women with normal BMI.

Methods: Non-tumorous breast tissue and fasting blood were collected from 72 women with BMI < 25 kg/m2 undergoing mastectomy at MSKCC. Breast inflammation was detected by the presence of CLS-B using CD68 immunohistochemistry. The primary objective was to determine if breast WATi in normal BMI individuals correlates with elevated aromatase levels in the breast, measured by qPCR, western blotting, immunofluorescence and enzyme activity. Secondary objectives included assessment of breast adipocyte size and circulating metabolic and inflammatory factors.

Results: Breast inflammation was present in 39% of women. Median BMI was 23.0 (range 18.4 to 24.9) in women with breast WATi versus 21.8 (range 17.3 to 24.6) in those without inflammation (P=0.04). Aromatase mRNA expression was positively correlated with WATi (CLS-B/cm2; P=0.002). Those with severe WATi had highest aromatase mRNA levels, compared to those with no or mild WATi (P=0.005). Aromatase protein, assessed by measuring adipose stromal cell-specific immunofluorescence or western blotting, and activity were also higher in CLS-B+ cases compared to CLS-B- (P<0.001). Breast WATi correlated with larger adipocytes (P=0.01) and higher circulating levels of C-reactive protein, leptin, insulin, and triglycerides (P<0.05). Insulin resistance, characterized by the homeostasis model (HOMA2-IR), correlated with breast WATi (P=0.004). Finally, leptin, a known inducer of aromatase and driver of cancer growth, correlated with higher breast aromatase levels (P=0.02) and larger adipocytes (P<0.01).

Conclusions: A metabolically unhealthy state occurs in women with inflamed breast adipose despite having a normal BMI. This subclinical inflammatory state is characterized by elevated aromatase in the breast, insulin resistance, and dysplipidemia. The presence of enlarged adipocytes in the breasts of normal BMI women with inflammation suggests a state of hyperadiposity which could not be predicted based on BMI alone. These findings indicate that normal BMI metabolic obesity may be associated with increased cancer risk. Our results suggest that objective measurements of adiposity rather than BMI may help to identify individuals at increased risk for disease.

Citation Format: Iyengar NM, Brown KA, Zhou XK, Subbaramaiah K, Giri DD, Gucalp A, Howe LR, Zahid H, Bhardwaj P, Wendel NK, Falcone DJ, Morrow M, Wang H, Williams S, Pollak M, Hudis CA, Dannenberg AJ. Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD5-05.

Abstract P1-09-14: Breast carcinoma with 21-gene recurrence score lower than 18: Rate of distant metastases in a large series with clinical follow-up

Background: The 21-gene recurrence score (RS) estimates the likelihood of distant recurrence and the benefit from chemotherapy in patients with early-stage node-negative, estrogen receptor (ER)-positive, HER2-negative breast carcinoma. The use of the assay resulted in a substantial reduction in adjuvant chemotherapy usage. In this study, we reviewed the outcome of patients with node-negative, ER+/HER2- breast cancer and low recurrence score treated at our center to further verify the prognostic value of the assay.

Design: We identified breast cancer patients treated at our center between 09/2008 and 08/2013 with ER-positive, HER2-negative breast cancer and known RS. We reviewed clinicopathological characteristics, RS, treatment and outcome data. The Institutional Review Board approved the study.

Results: We identified 1406 consecutive patients with early stage node negative ER+/HER2- breast cancer and low RS [RS 0-10: 510 (36%), RS 11-17: 896 (64%)] in the study period. The median age at breast cancer diagnosis was 56 years (range 22-90). Sixty-three (4%) patients were <40 years old at breast cancer diagnosis. A total of 1362 (97%) patients received endocrine therapy, and 170 (12%) received chemotherapy. The median follow up time was 46 months (range 1-85). Six (0.4%) of the 1406 patients developed biopsy proven distant metastases within 5 years of breast cancer diagnosis, 5 of which were in the RS 11-17 group (Table 1). Three of the 5 patients with RS 11-17 and distant metastases were younger than 40 years old at breast cancer diagnosis. In the RS 11-17 group, the absolute incidence of distant metastases among patients with breast cancer diagnosed at age younger than 40 years old is 7.1% (3/42), whereas the absolute incidence of distant metastases among patients ≥40 years is 0.2% (2/854).

Conclusion: Our results suggest that young age (<40 years old) might be a negative prognostic factor even in patients with low RS. Analysis of data from other studies is necessary to further validate this observation.

Table 1. Clinicopathologic characteristics of the 6 patients with ER-positive, HER2-negative, node-negative breast carcinoma of recurrence score <18 who developed distant metastasisPatients#1#2#3#4#5#6Age at diagnosis (years)505437713839Family history of breast/ ovarian cancerNoYesNoNoNoYesPersonal history of breast carcinomaNoIpsilateral DCISNoIpsilateral DCISNoNoTumor typeILCIDCIDCIDCIDCIDCTumor size (cm)2.11.32.72.31.62.1Tumor Grade222223LVINoNoNoNoYesNoER (%)909595959595PR (%)30585757595Oncotype DX RS51212131417SurgeryBTMTMBTMBCSBCSBTMRadiationNoNoNoYesYesNoEndocrine therapyYesYesYesYesNoYesChemoNoNoCMFNoNoNoTime interval to metastasis (months)584125204812Site of metastasisBoneMultipleLungMultipleMultipleBoneFollow-up (months)725359647142SurvivalAWDAWDAWDDODAWDAWDAbbreviations: RS, recurrence score; ILC, invasive lobular carcinoma; IDC, invasive ductal carcinoma; LVI, lymphovascular invasion; BTM, bilateral total mastectomy; TM, total mastectomy; BCS, breast conserving surgery; CMF, cyclofosphamide, metotrexate and 5-fluorouracil. AWD, alive with disease; DOD, died of disease.

Citation Format: Wen HY, Krystel-¬Whittemore M, Patil S, Pareja F, Bowser ZL, Dickler M, Norton L, Morrow M, Hudis C, Brogi E. Breast carcinoma with 21-gene recurrence score lower than 18: Rate of distant metastases in a large series with clinical follow-up [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-14.

Abstract BL2: Changing paradigms in the local therapy of breast cancer: Making less more

The ability of surgery to cure breast cancer has not changed over time. What has changed is that the cancers seen in the screening era are smaller and have fewer nodal metastases, making them more amenable to surgical cure. Only 25% of patients enrolled in the landmark NSABP B-06 trial had cT1N0 disease compared to 80% of those enrolled in NSABP B32, which began 15 years later. At the same time, improved systemic therapy options and a better understanding of tumor biology have led to greater success in treating micrometastatic disease. Systemic therapy is now widespread for early-stage breast cancers and often for longer durations with anti-HER2 therapy given for 12 months and endocrine therapy for 5-10 years. The progressive addition of therapies has increased the burden of treatment for patients at the same time it has improved outcomes. The beneficial effect of systemic therapy on local control and the lower disease burden seen today offer the opportunity to decrease the morbidity of surgery without compromising outcomes. The ACOSOG Z011 trial, now with follow-up of 10 years, demonstrated no difference in locoregional recurrence or survival among patients with metastases in 1–2 sentinel nodes after sentinel node biopsy alone or axillary dissection (ALND) when treated with breast-conserving surgery (BCS) and whole breast irradiation (RT). In 9/2010 we began prospectively utilizing Z11 eligibility criteria in patients with cT1-2 N0 cancers undergoing breast conservation with ALND reserved for those with >2 nodal metastases or gross extracapsular extension. Of the initial 723 consecutive, unselected patients, ALND was avoided in 84%. At a mean follow-up of 33 months (12–68), there were no isolated axillary recurrences. The 5-year Kaplan Meier rate of any nodal recurrence was 98% (95% CI 96–99). In the 251 patients considered “high risk” based on triple negative, HER2+, or age <50 years or a combination of these factors, ALND was required in 15.5% vs 15.9% of postmenopausal, ER+ patients (p=.89). The same principles led us to address the issue of what constitutes an optimal negative margin in women with invasive breast cancer undergoing BCS and RT. After a metaanalysis and review of other relevant literature, an SSO-ASTRO sponsored consensus committee concluded that evidence did not support routinely obtaining margins more widely clear than no ink on tumor, and that adherence to this recommendation, disseminated in late 2013 and published 2/14, had the potential to significantly reduce the use of re-excision. Since that time, the proportion of surgeons in a population-based sample endorsing no ink on tumor as an adequate margin rose to over 60%, compared to 11% in a similar survey conducted in 2006–7. This change in attitude has translated into a reduction in the use of additional surgery, both re-excision and mastectomy after initial lumpectomy. In a SEER sample from 2013–15, this resulted in a 9% absolute increase in the use of BCS during the study period. The use of neoadjuvant therapy offers further opportunities to decrease the morbidity of surgery and individualize local therapy in the future.

Citation Format: Morrow M. Changing paradigms in the local therapy of breast cancer: Making less more [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr BL2.

Abstract P3-13-07: Are there patients with T1-T2, node-negative breast cancer who are high-risk for locoregional recurrence?

Background: Indications for post-mastectomy radiotherapy (PMRT) in T1-T2, node negative (N0) breast cancer patients with “high-risk” features are controversial based on lack of consensus as to what constitutes “high-risk”, and variable results of small retrospective studies. The EORTC 22922 and MA20 trials reporting improved 10-year disease-free survival with nodal irradiation included high-risk N0 patients but these patients were not analyzed separately and did not receive modern systemic therapy. We sought to evaluate long-term locoregional control in T1-T2N0 patients with high-risk features undergoing mastectomy in the contemporary era.

Methods: We retrospectively identified patients with T1-T2N0 breast cancer with ≥1 high-risk feature treated with mastectomy from 1/2006-12/2011. High-risk features were defined as age <40 years, multifocal/multicentric disease, lymphovascular invasion (LVI), medial or central tumor location, and high nuclear grade. The primary outcome of interest was rate of LRR.

Results: Among 672 patients meeting inclusion criteria, 187 (28%) had 1 risk factor: 21 (3%) were age <40 years, 132 (20%) were multifocal/multicentric, and 34 (5%) had LVI; 449 (67%) patients had ≥2 high-risk features, and 36 patients with unknown grade were excluded from risk analysis. PMRT was received by only 15 (2%) patients. Clinicopathologic characteristics of the 657 patients treated without PMRT are shown in Table 1.

Table 1: Clinicopathologic characteristics, n = 657 Median (Range)Age, years49 (24-89)Tumor size, cm1.4 (<0.1-5.0) n (%)Ductal histology566 (86%)High nuclear grade*266 (40%)LVI232 (35%)Multifocal/multicentric447 (68%)Medial/central tumor226 (34%)Receptor status** ER+/HER2-438 (67%)HER2+123 (19%)ER-/HER2-70 (11%) n (%)Rate of LRR# of risk factors*  1183 (28%)3.8%2265 (40%)5.3%3143 (22%)4.9%4 or 532 (5%)9.4%*Unknown grade in 34 cases, excluded from risk analysis **Unknown receptor status in 26 cases

Sentinel node biopsy alone was performed in 98% of these patients. A median of 4 lymph nodes were retrieved (range 1-15). Adjuvant systemic therapy was received by 86% of patients. At median 5.6 years of follow-up, overall LRR rate was 4.7% (n = 31), with the majority (55%) of events involving the chest wall. Increasing tumor size was associated with LRR (HR 1.70, 95% CI 1.26–2.29, p = 0.006), while age, histology, grade, subtype, LVI, multifocality/multicentricity, and tumor location were not (all p > 0.05). Although rate of LRR increased from 3.8% to 9.4% with 1 vs. ≥4 high-risk features, a comparison of 1 vs. 2 vs. 3 vs. ≥4 risk factors was not significant by Kaplan-Meier estimation (p = 0.54).

Conclusions: A low LRR rate of 4.7% was seen in this large unselected cohort of T1-T2N0 cancers with "high-risk" features treated by mastectomy and systemic therapy without PMRT. While increasing tumor size was predictive, other features did not confer a higher risk of LRR either independently or together, and do not by themselves mandate the use of PMRT in this population.

Citation Format: Mamtani A, Patil S, Stempel M, Morrow M. Are there patients with T1-T2, node-negative breast cancer who are high-risk for locoregional recurrence? [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-07.

Abstract P4-04-11: Preferential expression of the chemokine receptor 8 (CCR8) on regulatory T cells (Treg) infiltrating human breast cancers represents a novel immunotherapeutic target

Treg cells are identified by the expression of the transcription factor FoxP3 and preserve immune homeostasis by the establishment and maintenance of peripheral tolerance. This suppressive function however, limits anti-tumor immune responses and represents a critical obstacle to immunotherapy. Safely targeting Treg cells will require selective elimination of tumor infiltrating Treg cells, as systemic depletion will lead to immune related adverse events. We hypothesize that differential gene expression analysis of Treg cells isolated from human breast tumors and peripheral blood will identify a tumor specific means to target Treg cells for the immunotherapy of breast cancer.

Methods: Tumor infiltrating lymphocytes were isolated from fresh operative specimens of patients undergoing surgery for primary invasive breast carcinoma. Lymphocytes were also isolated from normal breast tissue and peripheral blood buffy coat. T cell subsets including Treg cells were isolated by fluorescent activated cell sorting and analyzed by RNAseq. Mixed bone marrow chimeric mice were generated by reconstituting irradiated immunodeficient mice with a mixture of CCR8-/- + FoxP3-/- or CCR8+/+ + FoxP3-/- bone marrow, thus creating mice with Treg cells lacking CCR8 and controls.

Results: We found that Treg cells are more prevalent in breast tumors as opposed to normal breast tissue regardless of the biologic subtype of breast cancer (p<0.05). Gene expression profiling of Treg cells and CD4 T cells isolated from tumor or blood revealed a distinct tumor Treg cell gene signature. This signature was enriched for cytokine binding and chemokine receptor GO categories (FDR<0.005). Specifically, we identified CCR8 to be differentially and robustly expressed on tumor infiltrating Treg cells. This was validated by flow cytometry on over 50 primary breast cancers where the mean florescence intensity of CCR8 on Treg cells was at least twice that observed on conventional CD4 T cells (p<0.05). CCR8 expression on Treg cells also significantly correlated with higher-grade cancers (p<0.05). Using a data set generated by the Cancer Genome Atlas, we found that a high CCR8/FOXP3 gene expression ratio is strongly associated with worse disease free and overall survival of breast cancer (p<0.001) patients while FOXP3 gene expression level alone does not predict disease outcome. To investigate the role of CCR8 expression on Treg cells in a preclinical murine model of mammary carcinogenesis, we implanted syngeneic polyoma middle-T antigen-driven breast cancer cells in the mammary fat pads of mixed bone marrow chimeric mice in which Treg cells lack CCR8 expression. CCR8 deficiency in Treg cells significantly decreased primary tumor progression and distant metastases without any overt immunopathology (p<0.05).

Conclusions: Treg cells infiltrate human breast cancers and suppress anti-tumor immune responses. Our results demonstrate that CCR8 is selectively expressed by human breast cancer infiltrating Treg cells. Targeting CCR8 represents a promising immunotherapeutic approach for the treatment of patients with breast cancer. Depleting CCR8 antibodies are currently in development for additional preclinical and human studies.

Citation Format: Plitas G, Konopacki C, Wu K, Paula B, Morrow M, Rudensky A. Preferential expression of the chemokine receptor 8 (CCR8) on regulatory T cells (Treg) infiltrating human breast cancers represents a novel immunotherapeutic target. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-04-11.

Nipple-sparing mastectomy in patients with BRCA1/2 mutations and variants of uncertain significance

BACKGROUND

Nipple-sparing mastectomy (NSM) is associated with improved cosmesis and is being performed increasingly. Its role in BRCA mutation carriers has not been well described. This was a study of the indications for, and outcomes of, NSM in BRCA mutation carriers.

METHODS

BRCA mutation carriers who underwent NSM were identified. Details of patient demographics, surgical procedures, complications, and relevant disease stage and follow-up were recorded.

RESULTS

A total of 177 NSMs were performed in 89 BRCA mutation carriers between September 2005 and December 2013. Twenty-six patients of median age 41 years had NSM for early-stage breast cancer and a contralateral prophylactic mastectomy. Mean tumour size was 1·4 (range 0·1-3·5) cm. Sixty-three patients of median age 39 years had prophylactic NSM, eight of whom had an incidental diagnosis of ductal carcinoma in situ. There were no local or regional recurrences in the 26 patients with breast cancer at a median follow-up of 28 (i.q.r. 15-43) months. There were no newly diagnosed breast cancers in the 63 patients undergoing prophylactic NSM at a median follow-up of 26 (11-42) months. All patients had immediate breast reconstruction. Five patients (6 per cent) required subsequent excision of the nipple-areola complex for oncological or other reasons. Skin desquamation occurred in 68 (38·4 per cent) of the 177 breasts, and most resolved without intervention. Debridement was required in 13 (7·3 per cent) of the 177 breasts, and tissue-expander or implant removal was necessary in six instances (3·4 per cent).

CONCLUSION

NSM is an acceptable choice for patients with BRCA mutations, with no evidence of compromise to oncological safety at short-term follow-up. Complication rates were acceptable, and subsequent excision of the nipple-areola complex was rarely required.

Abstract P2-03-03: Feasibility of evaluation of breast tissue using confocal microscopy with strip mosaicing

Background: Confocal microscopic strip mosaicing (CSM) provides noninvasive optical sectioning and high resolution, which allows for imaging of nuclear and morphological detail in freshly excised tissue. CSM can image large areas of tissue at micron-level resolution in minutes, which may offer an advantage over standard histology that requires days. We have conducted a preliminary investigation of the feasibility of this technology for the evaluation of breast tissue from surgical excision specimens.

Design: In a prospective study, 80 fresh human breast tissue samples from surgical excision specimens of 24 patients were imaged using a prototype confocal strip scanner. Fresh tissue specimens were immersed in Acridine Orange (AO) for 45 seconds to stain the nuclei, then pressed against the glass imaging window and imaged with a 30X, 0.75 numerical aperture (measured) objective lens and a 488 nm laser. Images were acquired in two modes of contrast: in fluorescence (with AO), showing nuclear morphology, and in reflectance (endogenous), showing stroma. The use of fluorescence for nuclear staining mimics the use of hematoxylin in pathology, and the use of reflectance eosin. Use of two contrast modes allows the fluorescence image to be colorized purple and the reflectance image pink, producing confocal strip mosaics that mimic H&E histology in appearance. Specimens were subsequently fixed in formalin and routinely processed to obtain H&E stained sections. H&E and confocal images were compared by the study pathologist (M.M.)

Results: Freshly excised breast tissue samples as large as 2 cm x 2 cm were imaged in less than five minutes, with 1-micron resolution and measured optical sectioning of 6 microns. We compared the CSM images against standard histopathology images. In our series we evaluated the following histologies: 12 invasive carcinoma (11 ductal, 1 lobular), 3 ductal carcinoma in-situ, 3 lobular carcinoma in situ, 1 atypical lobular hyperplasia, 1 atypical ductal hyperplasia and various benign lesions such as fat necrosis, fibrocystic changes, and ductal hyperplasia. In confocal images invasive and in situ carcinoma as well as benign ducts and lobules were distinguished from surrounding stromal tissue. Limitations that are typically encountered in standard histology, such as distinguishing low grade ductal carcinoma in situ (DCIS) from lobular carcinoma in situ (LCIS) or atypical proliferations were encountered in the grayscale confocal images as well.

Conclusion: In this initial feasibility study, CSM produced images that could be diagnosed as benign or neoplastic by the study pathologist. Further study is needed to build an image library of breast histology and compare reproducibility of histologic diagnoses between CSM (grayscale and colorized images) and traditional optical microscopy, and assess interobserver reproducibility in diagnosis. CSM potentially provides rapid and noninvasive evaluation of breast parenchyma, and has a potential application for intraoperative margin assessment of resected breast specimens.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-03-03.