Prognostic Factors in Patients with Metastatic Breast Cancer with Bone-Only Metastases

This article describes the association between pain attributable to bone metastasis and location, as well as number and type of bone metastases at time of bone metastasis diagnosis in metastatic breast cancer patients with bone‐only metastases. The resulting outcomes analysis should allow for earlier interventions or identification for clinical trial involvement.

Background.

Patients with metastatic breast cancer with bone‐only metastases (BOM) are a unique patient population without consensus regarding high‐risk characteristics, which we sought to establish.

Methods.

We identified 1,445 patients with BOM followed for at least 6 months at MD Anderson Cancer Center from January 1, 1997, to December 31, 2015.

Results.

Seventy‐one percent (n = 936) of the 1,325 patients with BOM with available pain characterization were symptomatic at time of BOM diagnosis. Pain was more common in patients with lytic compared with blastic or sclerotic metastases (odds ratio [OR], 1.79; 95% confidence interval [CI,] 1.26–2.53) and multiple versus single bone metastases (OR, 1.37; 95% CI, 1.03–1.83). Poorer overall survival (OS) was also noted in patients with multiple bone metastases (median OS, 4.80 years; 95% CI, 4.49–5.07) compared with single bone metastasis (median OS, 7.54 years; 95% CI, 6.28–10.10) and in patients with metastases in both the axial and appendicular skeleton (median OS, 4.58 years; 95% CI, 4.23–4.96) compared with appendicular‐only (median OS, 6.78 years; 95% CI, 5.26–7.96) or axial‐only metastases (median OS, 5.62 years; 95% CI, 4.81–6.69). Black/non‐Hispanic patients had poorer outcomes, and patients aged 40–49 years at time of breast cancer diagnosis had significantly better OS compared with both younger and older patient groups.

Conclusion.

Overall, several risk features for decreased OS were identified, including multiple bone metastases and both axial and appendicular skeleton involvement. Multiple bone metastases and lytic bone metastases were associated with increased pain.

Implications for Practice.

Patients with metastatic breast cancer and bone‐only metastases (BOM) represent a poorly characterized patient subset. The ability to identify unique patient characteristics at time of BOM diagnosis associated with increased morbidity or mortality would allow for recognition of patients who would benefit from more aggressive therapy. In this study, the largest sample of patients with BOM thus far reported is characterized, highlighting several higher‐risk BOM groups, including those with multiple bone metastases and bone metastases in both the axial and appendicular skeleton at time of BOM diagnosis. In addition to tailoring current practices for these high‐risk patients, ongoing studies of these patients are indicated.

A Population of Heterogeneous Breast Cancer Patient-Derived Xenografts Demonstrate Broad Activity of PARP Inhibitor in BRCA1/2 Wild-Type Tumors

Background: Breast cancer patients who do not respond to neoadjuvant therapy have a poor prognosis. There is a pressing need for novel targets and models for preclinical testing. Here we report characterization of breast cancer patient-derived xenografts (PDX) largely generated from residual tumors following neoadjuvant chemotherapy.Experimental Design: PDXs were derived from surgical samples of primary or locally recurrent tumors. Normal and tumor DNA sequencing, RNASeq, and reverse phase protein arrays (RPPA) were performed. Phenotypic profiling was performed by determining efficacy of a panel of standard and investigational agents.Results: Twenty-six PDXs were developed from 25 patients. Twenty-two were generated from residual disease following neoadjuvant chemotherapy, and 24 were from triple-negative breast cancer (TNBC). These PDXs harbored a heterogeneous set of genomic alterations and represented all TNBC molecular subtypes. On RPPA, PDXs varied in extent of PI3K and MAPK activation. PDXs also varied in their sensitivity to chemotherapeutic agents. PI3K, mTOR, and MEK inhibitors repressed growth but did not cause tumor regression. The PARP inhibitor talazoparib caused dramatic regression in five of 12 PDXs. Notably, four of five talazoparib-sensitive models did not harbor germline BRCA1/2 mutations, but several had somatic alterations in homologous repair pathways, including ATM deletion and BRCA2 alterations.Conclusions: PDXs capture the molecular and phenotypic heterogeneity of TNBC. Here we show that PARP inhibition can have activity beyond germline BRCA1/2 altered tumors, causing regression in a variety of molecular subtypes. These models represent an opportunity for the discovery of rational combinations with targeted therapies and predictive biomarkers. Clin Cancer Res; 23(21); 6468-77. ©2017 AACR.

Effects of HLA status and HER2 status on outcomes in breast cancer patients at risk for recurrence - Implications for vaccine trial design

Immunotherapy, using peptide-based cancer vaccines is being studied to assess its potential in breast cancer. Trials of HLA-restricted peptide vaccines have been difficult to enroll given HLA subtype restrictions. It is necessary to determine the prognostic significance of HLA-status in breast cancer if patients who are ineligible to receive a vaccine due to their HLA-status are used as controls. The impact of targeted tumor associated antigen expression, when it effects eligibility is also important. We examined control patients from two randomized phase II trials that tested HER2-peptide vaccines to determine the effect of HLA-A2 status and HER2 expression on disease-free survival. The analysis showed that HLA-A2-status does not affect disease-free survival, regardless of HER2 expression suggesting that HLA-A2 negative patients can be used as control patients. Additionally, HER2 over-expression was associated with a better disease-free survival in this population, underscoring the need for additional therapies in HER2 low-expressing breast cancer. ClinicalTrials.gov Identifier: NCT00524277.

Impact of change in body mass index during neoadjuvant chemotherapy and survival among breast cancer subtypes

PURPOSE

We hypothesized that an increase in BMI category during neoadjuvant chemotherapy (NAC) would be associated with pathological complete response (pCR) rate and worse survival outcomes in primary breast cancer patients.

METHODS

We reviewed the records of 4029 patients with stage I-III breast cancer who had undergone NAC and definitive surgery at our institution between May 1, 1990 and April 30, 2013. BMI values at baseline and after NAC were recorded, and the corresponding BMI category was assessed with the WHO classification. Overall survival (OS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meier method, and multivariate Cox regression models were used to estimate the effect of covariates of interest on OS and RFS.

RESULTS

The median follow-up period was 3.95 years. A change in BMI category from normal to obese during NAC was independently associated with shorter OS duration than was maintaining a normal weight [hazard ratio (HR) 1.637; 95%CI 1.066-2.514; p = 0.0242]. Kaplan-Meier curves among breast cancer subtypes showed differences, and a decrease in BMI led to better RFS and OS rates in obese patients with HR+/HER2- disease; those who maintained BMI also showed better prognosis for triple-negative breast cancer (TNBC). We saw no association between BMI change and pCR rate.

CONCLUSION

Our data suggest that inability to maintain normal weight during NAC is a predictive marker of poor survival but not pCR. It may be important for patients to maintain a normal weight during NAC.

Revisiting the definition of estrogen receptor positivity in HER2-negative primary breast cancer

Background

Although 1% has been used as cut-off for estrogen receptor (ER) positivity, several studies have reported that tumors with ER < 1% have characteristics similar to those with 1% ≤ ER < 10%. We hypothesized that in patients with human epidermal growth factor 2 (HER2)-negative breast cancer, a cut-off of 10% is more useful than one of 1% in discriminating for both a better pathological complete response (pCR) rate to neoadjuvant chemotherapy and a better long-term outcome with adjuvant hormonal therapy. Our objectives were to identify a percentage of ER expression below which pCR was likely and to determine whether this cut-off value can identify patients who would benefit from adjuvant hormonal therapy.

Patients and methods

Patients with stage II or III HER2-negative primary breast cancer who received neoadjuvant chemotherapy followed by definitive surgery between June 1982 and June 2013 were included. Logistic regression models were used to assess the association between each variable and pCR. Cox models were used to analyze time to recurrence and overall survival. The recursive partitioning and regression trees method was used to calculate the cut-off value of ER expression.

Results

A total of 3055 patients were analyzed. Low percentage of ER was significantly associated with high pCR rate (OR = 0.99, 95% CI = 0.986-0.994, P < 0.001). The recommended cut-off of ER expression below which pCR was likely was 9.5%. Among patients with ER ≥ 10% tumors, but not those with 1%≤ER < 10% tumors, adjuvant hormonal therapy was significantly associated with long time to recurrence (HR = 0.24, 95% CI = 0.16-0.36, P < 0.001) and overall survival (HR = 0.32, 95% CI = 0.2-0.5, P < 0.001).

Conclusion

Stage II or III HER2-negative primary breast cancer with ER < 10% behaves clinically like triple-negative breast cancer in terms of pCR and survival outcomes and patients with such tumors may have a limited benefit from adjuvant hormonal therapy. It may be more clinically relevant to define triple-negative breast cancer as HER2-negative breast cancer with <10%, rather than <1%, of ER and/or progesterone receptor expression.

Contralateral prophylactic mastectomy rate and predictive factors among patients with breast cancer who underwent multigene panel testing for hereditary cancer

Although multigene panel testing is increasingly common in patients with cancer, the relationship between its use among breast cancer patients with non-BRCA mutations or variants of uncertain significance (VUS) and disease management decisions has not been well described. This study evaluated the rate and predictive factors of CPM patients who underwent multigene panel testing. Three hundred and fourteen patients with breast cancer who underwent multigene panel testing between 2014 and 2017 were included in the analysis. Of the 314 patients, 70 elected CPM. Election of CPM by gene status was as follows: BRCA carriers (42.3%), non-BRCA carriers (30.1%), and VUS (10.6%). CPM election rates did not differ between non-BRCA carriers and BRCA carriers (P = 0.6205). Among non-BRCA carriers, negative hormone receptor status was associated with CPM (P = 0.0115). For those with a VUS, hormone receptor status was not associated with CPM (P = 0.1879). Although the rate of CPM between BRCA carriers and non-BRCA carriers was not significantly different, the predictors of CPM were different in each group. Our analyses shed the light on the increasing use of CPM among patients who are non-BRCA carriers as well those with a VUS. Our study elucidates the differing predictive factors of CPM election among BRCA carriers, non-BRCA carries, and those with a VUS. Our findings reveal the need for providers to be cognizant that non-BRCA genes and VUS drive women to elect CPM despite the lack of data for contralateral breast cancer risk associated with these genes.

Phase Ib trial of folate binding protein (FBP)-derived peptide vaccines, E39 and an attenuated version, E39': An analysis of safety and immune response

In this randomized phase Ib trial, we tested combining the E39 peptide vaccine with a vaccine created from E39', an attenuated version of E39. Patients with breast or ovarian cancer, who were disease-free after standard of care therapy, were enrolled and randomized to one of three arms. Arm EE received six E39 inoculations; arm EE' received three E39 inoculations followed by three E39'; and arm E'E received three E39' inoculations, followed by three E39. Within each arm, the first five patients received 500 μg of peptide and the remainder received 1000 μg. Patients were followed for toxicity, and immune responses were measured. This initial analysis after completion of the primary vaccination series has confirmed the safety of both vaccines. Immune analyses suggest incorporating the attenuated version of the peptide improves immune responses and that sequencing of E39 followed by E39' might produce the optimal immune response.

TRIAL REGISTRATION

NCT02019524.

Abstract P6-03-05: Risk of needle-track seeding with serial ultrasound guided biopsies in triple negative breast cancer

Background: Image-guided percutaneous needle biopsy of the breast is a common procedure. In breast cancer patients (pts) undergoing core biopsies and surgical resection on the same day, the rate of tumor cell displacement along the needle track has been reported to be up to 50%. However, the clinical significance of this finding in triple negative breast cancer (TNBC) patients (pts) undergoing serial biopsies while receiving neoadjuvant chemotherapy (NACT) is unknown. Here we report the incidence of needle-track seeding (NTS) in a cohort of TNBC pts enrolled on a molecular triaging protocol involving serial biopsies of the index breast lesion.

Methods: We reviewed the clinical records of 144 consecutive TNBC pts enrolled on a molecular triaging protocol at MD Anderson Cancer Center. Per protocol, all pts underwent a pre-treatment research biopsy and were initiated on anthracycline based NACT (AC). Pts with inadequate response to front-line NACT were encouraged to undergo additional biopsies of the index breast lesion prior to switching therapies. Serial breast ultrasound (US) was performed to monitor therapeutic response and incidental evidence of needle-track seeding noted on US was documented.

Results: Clinicopathological characteristics of the pts are summarized in Table 1. 89% (128/144) of pts had a diagnostic breast biopsy done at another center prior to presenting at MDACC. To date, we have performed 209 US guided biopsies of index breast lesions in 144 pts. 92% (193/209) of these biopsies were done mainly for research purposes. 1.4% (2/144) of pts were found to have evidence of NTS on follow up US. The first pt had a T1N0 (1.9cm), grade 3, invasive ductal carcinoma (IDC) at diagnosis. She underwent a diagnostic biopsy followed by a research biopsy before initiating AC. She was found to have NTS as well as progression of disease (PD) on follow up US after 2 cycles of AC. The second pt had a T2N0 (3cm), grade 3 IDC at diagnosis. She underwent a diagnostic biopsy at another center, followed by a research biopsy before initiating AC. Like the first pt, she was found to have NTS and PD on follow up US after 2 cycles of AC. Both pts are currently on neoadjuvant clinical trials of novel agents.

Conclusion: The rate of NTS detected on US in TNBC pts undergoing serial biopsies of index breast lesions while receiving NACT is low and further studies are needed to determine the impact of serial biopsies on long term outcomes in TNBC.

Table 1: Patient CharacteristicsCharacteristicN=144Age - Median (years, interquartile range)55 (46-62)Tumor Size Mean (cm, standard deviation)3.4 (2.2)T1 – n(%)35 (24)T2 – n(%)89 (62)T3 – n(%)19 (13)T4 – n(%)1 (1)Clinical Nodal Status Negative – n(%)74 (51)Positive – n(%)70 (49)Grade 1 – n(%)1 (1)2 – n(%)17 (12)3 – n(%)124 (86)Unknown – n(%)2 (1)Histologic Subtype Invasive ductal carcinoma – n(%)121 (84)Invasive lobular carcinoma – n(%)2 (1)Mixed ductal and lobular carcinoma – n(%)3 (2)Metaplastic carcinoma – n(%)13 (9)Not specified – n(%)5 (3)Laterality Right – n(%)72 (50)Left – n(%)72 (50)

Citation Format: Yam C, Santiago L, Candelaria RP, Adrada BE, Rauch GM, Hess KR, Litton JK, Piwnica-Worms H, Mittendorf EA, Ueno NT, Lim B, Murthy RK, Damodaran S, Helgason T, Huo L, Thompson AM, Gilcrease MZ, Symmans WF, Moulder SL, Yang W. Risk of needle-track seeding with serial ultrasound guided biopsies in triple 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 P6-03-05.

Abstract P1-16-01: Tumor subtype concordance between breast and bone biopsies in bone only metastasis patients

Background:

Bone is the most common site of metastasis in metastatic breast cancer patients. Notably, bone biopsy is considered technically challenging with concerns regarding yield and reproducibility of immunohistochemistry technique. Our goal was to assess tumor subtype concordance between breast and bone biopsies done in patients with bone only metastases.

Methods:

We identified patients followed at MD Anderson Cancer Center for at least 6 months from 01/01/1997 to 12/31/2015 with bone as first site of metastasis. Breast and bone biopsy immunohistochemistry was used to categorize tumor subtype with hormone receptor positive (HR+) defined as ER or PR &gt;1%. The following four tumor subtypes were identified: luminal A-like (HR+, HER2-), luminal B-like (HR+, HER2+), triple negative (HR-, HER2-), and HER positive (HR-, HER2+).

Results:

We identified 805 bone only metastasis patients with positive bone biopsies, 395 (49%) of which had hormone receptor and HER2 characterization available. Of these 395 patients, 293 (74%) were luminal A-like, 44 (11%) were luminal B-like, 51 (13%) were triple negative, and 7 (2%) were HER2 positive. Of these patients, we identified 281 patients with tumor subtype data available for both primary breast biopsy and bone metastasis biopsy, of which 237 (84%) were concordant, while 44 (16%) were discordant (Table 1).

Table 1. Concordance between breast and bone biopsies based on initial breast biopsy tumor subtypeBreast Biopsy Tumor Subtype (n = 281)Concordance with Bone Biopsy Tumor SubtypeDiscordant Bone Biopsy Tumor SubtypeLuminal A-like, HR+ HER2- (225/80%)Concordant: 199 (88%), Discordant: 26 (12%)10 Luminal B-like, 16 Triple negativeLuminal B-like, HR+ HER2+ (33/12%)Concordant: 19 (58%), Discordant: 14 (42%)11 Luminal A-like, 2 Triple negative, 1 HER2 positiveTriple negative, HR- HER2- (20/7%)Concordant: 16 (80%), Discordant: 4 (20%)3 Luminal A-like, 1 Luminal B-likeHER2 positive, HR- HER2+ (3/1%)Concordant: 3 (100%), Discordant: 0 (0%)NA

Conclusions:

When available, bone biopsy tumor subtype had significant concordance with breast biopsy tumor subtype in this large study of bone only metastasis patients. Discordant tumor subtype results were more common in patients with luminal B-like tumor subtype on initial breast biopsy.

Citation Format: Parkes AM, Clifton KK, Al Awadhi A, Oke OC, Warneke CL, Litton JK, Hortobagyi GN. Tumor subtype concordance between breast and bone biopsies in bone only metastasis patients [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 P1-16-01.

Abstract P3-04-11: Implications of somatic TP53 and PIK3CA mutations in patients with metastatic breast cancer who underwent germline BRCA testing

Background: TP53 and PIK3CA are the most frequently mutated genes in breast cancer. However, there is limited data evaluating the impact of somatic mutations in TP53 and/or PIK3CA patients (pts) with metastatic breast cancer (MBC) who have undergone germline testing for BRCA mutations. Here, we report the frequency of somatic TP53 and PIK3CA mutations in MBC pts who previously underwent germline BRCA (gBRCA) testing and evaluate their impact on long-term outcomes.

Methods: We identified pts with MBC from our prospectively maintained high risk genetics database who underwent gBRCA testing and had somatic mutation testing performed for TP53 and/or PIK3CA through hotspot sequencing of single genes or as part of a next generation sequencing panel. Univariable logistic regression was used to evaluate associations between clinicopathological characteristics, including gBRCA status, and the presence of somatic TP53 and PIK3CA mutations. Overall survival (OS) was defined as the time from diagnosis to death from any cause. Multivariable cox regression analysis was used to identify independent predictors of OS.

Results: 104 pts met all inclusion criteria. Somatic mutations in TP53 and PIK3CA were found in 46% (39/84) and 23% (24/104) of tested pts, respectively. Associations between clinicopathological characteristics and somatic TP53 and PIK3CA mutation status are summarized in Table 1. Pts with hormone receptor positive (HR+) disease were less likely to have TP53 mutations (odds ratio [OR]: 0.28, 95% confidence interval [CI]: 0.11-0.70, p=0.007) but more likely to harbor PIK3CA mutations (OR: 3.27, 95% CI: 1.11-9.62, p=0.031). There were no significant associations between gBRCA mutation status and somatic TP53 or PIK3CA mutations. On multivariable analysis, somatic TP53 mutations (adjusted hazard ratio [aHR]: 1.98, 95% CI: 1.10-3.58, p=0.023) and de novo metastatic disease (aHR=2.88, 95% CI: 1.26-6.58, p=0.012) independently predicted poorer OS, while HR+ disease (aHR: 0.40, 95% CI: 0.21-0.74, p=0.004) and HER2+ disease (aHR: 0.33, 95% CI: 0.13-0.83, p=0.019) were significantly associated with improved OS. PIK3CA mutations (aHR: 1.20, 95% CI: 0.59-2.44, p=0.62) and gBRCA mutations (aHR: 0.78, 95% CI: 0.33-1.83, p=0.57) did not significantly impact OS in this study.

Conclusion: In this study, somatic TP53 mutations independently predicted worse OS in pts with MBC after adjusting for significant covariates, including gBRCA mutation status. These findings should be validated in a larger cohort of pts.

Table 1: Association between patient characteristics and somatic TP53 and PIK3CA mutation status TP53  PIK3CA   TP53 mutant (n=39)TP53 wild type (n=45)p valuePIK3CA mutant (n=24)PIK3CA wild type (n=80)p valueMedian Age – years (Interquartile Range)37 (33-47)39 (36-44)0.93739 (34-46)38 (34-43)0.494gBRCA mutant – n(%)3 (8)11 (24)0.0511 (4)15 (19)0.116ER/PR positive - n(%)17 (44)33 (73)0.00719 (79)43 (54)0.031HER2 positive - n(%)8 (21)6 (13)0.3827 (29)10 (13)0.060De Novo Metastatic – n(%)6 (15)8 (18)0.7693 (13)16 (20)0.409Visceral Disease – n(%)23 (59)26 (58)0.91215 (63)47 (59)0.743

Citation Format: Yam C, Gutierrez Barrera A, Huang D, Lin X, Litton JK, Arun B. Implications of somatic TP53 and PIK3CA mutations in patients with metastatic breast cancer who underwent germline BRCA testing [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 P3-04-11.

Abstract P1-07-22: Androgen receptor positivity is associated with nodal disease in triple negative breast cancer

Background: Gene expression profiling (GEP) has identified several molecularly distinct subtypes of triple negative breast cancer (TNBC). Currently, GEP-based molecular diagnostics are not routinely used in clinical decision making due to the lack of proven benefit, costs involved and long turnaround time. However, two molecularly distinct subtypes of TNBC, the luminal androgen receptor (AR) and mesenchymal subtypes, have surrogate CLIA-certified immunohistochemical (IHC) markers, AR and vimentin (VM), respectively, which have the potential for application in the clinic. Here we report the rates of AR and VM positivity and their association with clinicopathological characteristics in a cohort of TNBC pts receiving NACT.

Methods: As part of an ongoing molecular triaging protocol, 144 pts with stage I-III TNBC underwent a pretreatment biopsy for molecular characterization (MC) prior to initiating neoadjuvant chemotherapy (NACT). IHC for AR and VM were performed using commercially available antibodies. AR+ and VM+ were defined as ≥10% and ≥50% staining, respectively. Pts were randomized 2:1 to know (intervention arm, n=93) and not know (control arm, n=51) the MC results. The charts of pts randomized to the intervention arm were reviewed. Categorical variables were analyzed using Fisher's exact test. Ordinal and continuous variables were analyzed using the Wilcoxon rank-sum test and Student's t test as appropriate.

Results: 31% (29/93) and 16% (15/93) of pts were AR+ and VM+, respectively. Only 4% (4/93) of pts were both AR+ and VM+. Clinicopathological characteristics are summarized in Table 1. AR+ pts were more likely to have clinically node positive disease as compared to AR- pts (66% vs 34%, p=0.007). There were no significant differences in clinical tumor size or grade between AR+ and AR- pts. VM+ and VM- pts had similar clinicopathological characteristics.

Conclusion: Pts with AR+ TNBC were more likely to have node positive disease. The impact of AR+ on long term outcomes should be investigated in prospective studies.

Table 1: Association between patient characteristics and AR/VM status AR  VM   AR+ (n=29)AR- (n=64)p-valueVM+ (n=15)VM- (n=78)p-valueAge - Median (years, interquartile range)58 (48-65)52 (46-61)0.05855 (48-64)56 (47-62)0.88Clinical Tumor Size      Mean (cm, standard deviation)3.5 (1.8)3.0 (1.8)0.2872.7 (1.7)3.3 (1.9)0.31T1 – n(%)5 (17)21 (33)0.2307 (47)19 (24)0.098T2 – n(%)21 (72)36 (56) 7 (47)50 (64) T3 – n(%)3 (10)7 (11) 1 (7)9 (12) Clinical Nodal Status      Negative – n(%)10 (34)42 (66)0.0078 (53)44 (56)1.00Positive – n(%)19 (66)22 (34) 7 (47)34 (44) Grade      2 – n(%)6 (21)5 (8)0.0763 (20)8 (10)0.293 – n(%)23 (79)59 (92) 12 (80)70 (90) 

Citation Format: Yam C, Huo L, Hess KR, Litton JK, Yang W, Piwnica-Worms H, Mittendorf EA, Ueno NT, Lim B, Murthy RK, Damodaran S, Helgason T, Thompson AM, Santiago L, Candelaria RP, Rauch GM, Adrada BE, Symmans WF, Gilcrease MZ, Moulder SL. Androgen receptor positivity is associated with nodal disease in triple 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 P1-07-22.

Primary analysis of a prospective, randomized, single-blinded phase II trial evaluating the HER2 peptide GP2 vaccine in breast cancer patients to prevent recurrence

GP2 is a HER2-derived, HLA-A2+ restricted peptide. Phase I studies showed GP2 administered with GM-CSF to be safe and immunogenic. Here we report the primary analysis of a prospective, randomized, multicenter phase II adjuvant trial conducted to determine the vaccine's efficacy. The trial enrolled HLA-A2+, clinically disease-free, node-positive and high-risk node-negative breast cancer patients with tumors expressing HER2 (immunohistochemistry[IHC] 1+-3+). Patients were randomized to GP2+GM-CSF versus GM-CSF alone. Disease-free survival (DFS) was analyzed in intention-to-treat (ITT) and per-treatment cohorts; pre-specified subgroup analyses were performed for patients with IHC 3+ or FISH+ disease. The trial enrolled 180 patients; 89 received GP2+GM-CSF and 91 received GM-CSF alone. The groups were well-matched for clinicopathologic characteristics. Toxicities have been minimal. The Kaplan-Meier estimated 5-year DFS rate in the ITT analyses was 88% (95% CI:78-94%) in vaccinated vs. 81% (95% CI:69-89%) (P = 0.43) in control patients after a 34 month median follow-up. In the per-treatment analysis, the estimated 5-year DFS rates were 94% (95% CI:83-98%) and 85% (73-92%) (P = 0.17). In IHC 3+/FISH+ patients, the estimated 5-year DFS rate was 94% (82-98%) in vaccinated patients (n = 51) vs. 89% (71-96%) in control patients (n = 50), (P = 0.86) in the ITT analyses and 100% vs. 89% (71-96%) in vaccinated vs. control patients in the per-treatment analyses (P = 0.08). While the overall ITT analysis did not demonstrate benefit to vaccination, this trial confirmed that the GP2 vaccine is safe and suggests that vaccination may have clinical activity, particularly in patients with HER2 overexpression who received the full vaccine series (ie per-treatment group).

Stomatitis associated with mammalian target of rapamycin inhibition: A review of pathogenesis, prevention, treatment, and clinical implications for oral practice in metastatic breast cancer

BACKGROUND

Patients with metastatic breast cancer may develop oral morbidities that result from therapeutic interventions. Mammalian target of rapamycin (mTOR) inhibitor-associated stomatitis (mIAS) is a common adverse event (AE), secondary to mTOR inhibitor therapy, that can have a negative impact on treatment adherence, quality of life, and health care costs. A multidisciplinary team approach is important to minimize mIAS and to maximize treatment benefits to patients with breast cancer. In this review, we discuss the pathophysiology, diagnosis, and natural history of mIAS. Current and new management strategies for the prevention and treatment of mIAS are described in the context of fostering a coordinated team care approach to optimizing patient care.

TYPES OF STUDIES REVIEWED

The authors conducted a PubMed search from 2007 through 2017 using the terms "stomatitis," "mIAS," "everolimus," "mTOR," "metastatic breast cancer," and "oral care." They selected articles published in peer-reviewed journals that reported controlled trials and evidence-based guidelines.

RESULTS

mIAS can be distinguished from mucositis caused by cytotoxic chemotherapy or radiotherapy on the basis of cause, clinical presentation, and treatment paradigms. Specific preventive and therapeutic management strategies can be implemented across the continuum of patient oral health care.

PRACTICAL IMPLICATIONS

Oral health care providers are on the frontline of oral health care for patients with metastatic breast cancer and are uniquely positioned to provide patient education, advocate accurate reporting of mIAS, and support early identification, monitoring, and prompt intervention to mitigate the severity and duration of this manageable, potentially dose-limiting AE.

A feasibility study of neoadjuvant talazoparib for operable breast cancer patients with a germline BRCA mutation demonstrates marked activity

This study was undertaken to determine the feasibility of enrolling breast cancer patients on a single-agent-targeted therapy trial before neoadjuvant chemotherapy. Specifically, we evaluated talazoparib in patients harboring a deleterious BRCA mutation (BRCA+). Patients with a germline BRCA mutation and ≥1 cm, HER2-negative primary tumors were eligible. Study participants underwent a pretreatment biopsy, 2 months of talazoparib, off-study core biopsy, anthracycline, and taxane-based chemotherapy ± carboplatin, followed by surgery. Volumetric changes in tumor size were determined by ultrasound at 1 and 2 months of therapy. Success was defined as 20 patients accrued within 2 years and <33% experienced a grade 4 toxicity. The study was stopped early after 13 patients (BRCA1 + n = 10; BRCA2 + n = 3) were accrued within 8 months with no grade 4 toxicities and only one patient requiring dose reduction due to grade 3 neutropenia. The median age was 40 years (range 25–55) and clinical stage included I (n = 2), II (n = 9), and III (n = 2). Most tumors (n = 9) were hormone receptor-negative, and one of these was metaplastic. Decreases in tumor volume occurred in all patients following 2 months of talazoparib; the median was 88% (range 30–98%). Common toxicities were neutropenia, anemia, thrombocytopenia, nausea, dizziness, and fatigue. Single-agent-targeted therapy trials are feasible in BRCA+ patients. Given the rapid rate of accrual, profound response and favorable toxicity profile, the feasibility study was modified into a phase II study to determine pathologic complete response rates after 4–6 months of single-agent talazoparib.

An investigational PARP inhibitor seems safe and possibly effective when given ahead of surgery to women with BRCA-mutated breast cancer. Jennifer Litton and colleagues from the University of Texas MD Anderson Cancer Center in Houston, USA, conducted a small feasibility study to see if patients with stage I-III breast cancer and inherited mutations in BRCA1 or BRCA2 would put off their standard course of chemotherapy ahead of surgery to first receive two months of talazoparib, an experimental inhibitor of poly ADP ribose polymerase (PARP), an enzyme involved in DNA damage repair. The trial was a resounding success. In fact, owing to rapid patient enrollment, decreases in tumor volume among all 13 participants and few signs of serious side effects, the researchers amended the study protocol to give talazoparib for longer and test for therapeutic efficacy.

Synthetic Lethality of PARP Inhibitors in Combination with MYC Blockade Is Independent of BRCA Status in Triple-Negative Breast Cancer

PARP inhibitors (PARPi) benefit only a fraction of breast cancer patients. Several of those patients exhibit intrinsic/acquired resistance mechanisms that limit efficacy of PARPi monotherapy. Here we show how the efficacy of PARPi in triple-negative breast cancers (TNBC) can be expanded by targeting MYC-induced oncogenic addiction. In BRCA-mutant/sporadic TNBC patients, amplification of the MYC gene is correlated with increased expression of the homologous DNA recombination enzyme RAD51 and tumors overexpressing both genes are associated with worse overall survival. Combining MYC blockade with PARPi yielded synthetic lethality in MYC-driven TNBC cells. Using the cyclin-dependent kinase inhibitor dinaciclib, which downregulates MYC expression, we found that combination with the PARPi niraparib increased DNA damage and downregulated homologous recombination, leading to subsequent downregulation of the epithelial-mesenchymal transition and cancer stem-like cell phenotypes. Notably, dinaciclib resensitized TBNC cells, which had acquired resistance to niraparib. We found that the synthetic lethal strategy employing dinaciclib and niraparib was also highly efficacious in ovarian, prostate, pancreatic, colon, and lung cancer cells. Taken together, our results show how blunting MYC oncogene addiction can leverage cancer cell sensitivity to PARPi, facilitating the clinical use of c-myc as a predictive biomarker for this treatment.Significance: Dual targeting of MYC-regulated homologous recombination and PARP-mediated DNA repair yields potent synthetic lethality in triple-negative breast tumors and other aggressive tumors characterized by MYC overexpression. Cancer Res; 78(3); 742-57. ©2017 AACR.

BRCA mutations in women with inflammatory breast cancer

BACKGROUND

Inflammatory breast cancer (IBC) often affects women at a relatively young age. To the authors' knowledge, the rate of BRCA variants among patients with IBC is not known. To determine the association between BRCA status and IBC, the authors evaluated its rate and compared the clinicopathologic characteristics of patients with IBC with those of patients with other breast cancers (non-IBC).

METHODS

Patients who presented at the study institution's cancer genetics program and who underwent BRCA genetic testing were included in the current study. The authors compared clinicopathologic data between patients with IBC and those with non-IBC using propensity score matching to identify predictors.

RESULTS

A total of 1789 patients who underwent BRCA genetic testing (1684 with non-IBC and 105 with IBC) were included. BRCA pathogenic variants were found in 27.3% of patients with non-IBC and 18.1% of patients with IBC (P = .0384). After propensity score matching, there were no significant differences noted between patients with IBC and those with non-IBC, including the rate of BRCA pathogenic variants (P = .5485). However, a subgroup analysis of the 479 patients with BRCA pathogenic variants demonstrated that patients with IBC (19 patients) were diagnosed at significantly younger ages compared with patients with non-IBC (P = .0244).

CONCLUSIONS

There was no clear association observed between BRCA pathogenic variants and IBC. However, among patients who tested positive for BRCA pathogenic variants, those with IBC were younger at the time of diagnosis compared with those with non-IBC breast cancers. These results confirm that genetic testing is important for patients with IBC who meet the current clinical criteria for genetic testing in breast cancer. Cancer 2018;124:466-74. © 2017 American Cancer Society.

NCCN Guidelines Insights: Genetic/Familial High-Risk Assessment: Breast and Ovarian, Version 2.2017

The NCCN Clinical Practice Guidelines in Oncology for Genetic/Familial High-Risk Assessment: Breast and Ovarian provide recommendations for genetic testing and counseling for hereditary cancer syndromes and risk management recommendations for patients who are diagnosed with a syndrome. Guidelines focus on syndromes associated with an increased risk of breast and/or ovarian cancer. The NCCN Genetic/Familial High-Risk Assessment: Breast and Ovarian panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. The NCCN Guidelines Insights summarize the panel's discussion and most recent recommendations regarding risk management for carriers of moderately penetrant genetic mutations associated with breast and/or ovarian cancer.

Rapid Breast Cancer Disease Progression Following Cyclin Dependent Kinase 4 and 6 Inhibitor Discontinuation

Background: CDK 4 and 6 inhibitors (CDK4/6i), which arrest unregulated cancer cell proliferation, show clinical efficacy in breast cancer. Unexpectedly, a patient treated on a CDK4/6i-based trial, as first-line therapy in metastatic breast cancer, developed rapid disease progression following discontinuation of study drug while receiving standard second-line therapy off trial. We thus sought to expand this observation within a population of patients treated similarly at The University of Texas MD Anderson Cancer Center.

Methods: Using an IRB-approved protocol, 4 patients previously enrolled on CDK4/6i trials were analyzed for outcomes after discontinuing study drug. These patients were treated on a randomized trial of first-line endocrine therapy +/- a CDK4/6i. Rapid disease progression was defined as progression occurring within 4 months of CDK4/6i discontinuation.

Results: In total, 4 patients developed rapid disease progression and died; 2 of whom died within 6 months of CDK4/6i discontinuation.

Conclusion: This case series suggests a potential for rapid disease progression following CDK4/6i discontinuation. However, the clinical course following progression must be validated in large CDK4/6i clinical trials and standard-of-care cohorts. If confirmed, such observations may alter the algorithm for subsequent therapy in patients with disease progression on CDK4/6i. Nevertheless, the need remains to define a mechanistic basis for this rapid progression and formulate alternative therapeutic strategies.

Abstract CT162: Pre-specified interim analysis in a prospective, randomized phase II trial of trastuzumab vs trastuzumab + NeuVax to prevent breast cancer recurrence in HER2+ breast cancer patients

Introduction: The HER2-targeted monoclonal antibody, trastuzumab (Tz), is standard of care (SOC) for HER2-positive (HER2+) breast cancer (BCa) and has been shown to reduce recurrence. We have previously shown that NeuVax (E75 peptide + GM-CSF), a HER2-targeted peptide vaccine, is safe, immunogenic, and may have synergistic clinical efficacy when combined with Tz. Given the known cardiac toxicity of Tz, there is concern that adding a HER2-directed vaccine to Tz therapy may exacerbate this effect. We are currently enrolling patients (pts) in a multi-center, prospective, randomized, single-blinded, placebo-controlled phase II trial combining Tz and Neuvax in the adjuvant setting to prevent recurrence in HER2+ BCa pts. Here, we present the initial safety data.

Methods: HLA-A2/A3+ BCa pts with stage I-III HER2+ disease at high risk for recurrence (pts not achieving complete response after Tz-containing neoadjuvant therapy or those undergoing up-front surgery with any node-positive disease if ER/PR- or ≥4 positive nodes if ER/PR+) were enrolled after SOC surgery, radiation and neo-adjuvant/adjuvant chemotherapy with approved Tz-containing regimen. Pts were randomized to receive Tz and NeuVax in the vaccine group (VG) or Tz and GM-CSF only in the control group (CG). Pts received vaccinations of NeuVax or GM-CSF intradermally every 3 weeks for 6 total vaccinations (primary vaccine series, PVS) starting with the third dose of Tz maintenance therapy. Starting 6 months after the completion of the PVS, pts received four booster inoculations, one every 6 months. Cardiac ejection fraction (EF) was assessed by either echo or MUGA at baseline and serially during treatment. Demographic and safety data were collected and analyzed. Safety analysis was initiated after enrollment of the 50th patient.

Results: To date, we have enrolled 50 pts (VG n=22, CG n=28). There were no significant clinicopathologic differences between groups. There were no related grade 4 or 5 toxicities and no differences in related toxicities between the VG and CG (Grade 1: 96% vs 98.5%; Grade 2: 3.2% vs 1.5%; Grade 3: 0.8% vs 0%, p=0.14). There was no significant reduction in EF pre- to post-treatment in either group (VG: 61.1±5.4% vs 60.1±4.8%, p=0.55; CG: 62.3±5.7% vs 61.9±4.0%, p=0.74) and there was no difference in change between groups (p=0.54).

Conclusion: The combination of Tz and Neuvax in HER2+ BCa pts is well tolerated and the cardiac effects from Tz are not worsened by the addition of NeuVax. We will continue to enroll up to our goal of 100 pts in this ongoing trial, and will report immunologic and clinical outcomes in the planned primary analysis after 24-months follow-up.

Citation Format: Kaitlin M. Peace, Jennifer K. Litton, Rashmi Murthy, Timothy J. Vreeland, Diane F. Hale, Doreen O. Jackson, John S. Berry, Alfred F. Trappey, Garth S. Herbert, Guy T. Clifton, Mark O. Hardin, George E. Peoples, Elizabeth A. Mittendorf. Pre-specified interim analysis in a prospective, randomized phase II trial of trastuzumab vs trastuzumab + NeuVax to prevent breast cancer recurrence in HER2+ breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT162. doi:10.1158/1538-7445.AM2017-CT162

Systemic Treatment Strategies for Patients with Hereditary Breast Cancer Syndromes

Hereditary breast cancer syndromes are associated with an increased risk of breast cancer and constitute a unique patient population, making up approximately 5%-10% of breast cancer cases in the United States. By virtue of the germline mutations that define these syndromes, invasive breast cancers in these patients have unique mechanisms that can be rationally targeted for therapeutic opportunities distinct from standard of care treatments in nongermline mutation associated breast cancers. This review intends to describe existing data on several of the most common hereditary breast cancer syndromes, including BRCA-related breast cancer syndrome, Li-Fraumeni syndrome, Cowden syndrome, Peutz-Jeghers syndrome, and hereditary diffuse gastric cancer syndrome, specifically focusing on rational therapeutics utilized in these distinct patient subgroups and completed or ongoing clinical trials evaluating their efficacy. By exploiting the distinct biologic features associated with these syndromes, tailored treatment strategies have the potential for improved efficacy and lower toxicity. Knowledge of the emergence of these targeted cancer therapies is critical for appropriate management in these patients, extending beyond treatment to highlight the need for appropriate genetic screening to allow for early recognition of these patients and therefore appropriate treatment.

IMPLICATIONS FOR PRACTICE

Molecular testing allows for identification of germline mutations that place individuals at high risk for breast cancer and that are associated with distinct histopathology and molecular characteristics that define the invasive breast cancer cases that these patients develop. These unique characteristics may ultimately provide rational targets for systemic treatments with improvements in both morbidity and efficacy. Identification of patients with these germline mutations is important for not only appropriate screening and prophylaxis, but knowledge of therapies specifically targeting several of the most common hereditary breast cancer syndromes is essential to ensure appropriate treatment of invasive breast cancers in these patients.

Targeting the PI3K/AKT/mTOR Pathway for the Treatment of Mesenchymal Triple-Negative Breast Cancer: Evidence From a Phase 1 Trial of mTOR Inhibition in Combination With Liposomal Doxorubicin and Bevacizumab

Importance

Triple-negative breast cancer (TNBC) classified by transcriptional profiling as the mesenchymal subtype frequently harbors aberrations in the phosphoinositide 3-kinase (PI3K) pathway, raising the possibility of targeting this pathway to enhance chemotherapy response. Up to 30% of mesenchymal TNBC can be classified histologically as metaplastic breast cancer, a chemorefractory group of tumors with a mixture of epithelial and mesenchymal components identifiable by light microscopy. While assays to identify mesenchymal TNBC are under development, metaplastic breast cancer serves as a clinically identifiable surrogate to evaluate potential regimens for mesenchymal TNBC.

Objective

To assess safety and efficacy of mammalian target of rapamycin (mTOR) inhibition in combination with liposomal doxorubicin and bevacizumab in patients with advanced metaplastic TNBC.

Design, Setting, and Participants

Phase 1 study with dose escalation and dose expansion at the University of Texas MD Anderson Cancer Center of patients with advanced metaplastic TNBC. Patients were enrolled from April 16, 2009, to November 4, 2014, and followed for outcomes with a cutoff date of November 1, 2015, for data analysis.

Interventions

Liposomal doxorubicin, bevacizumab, and the mTOR inhibitors temsirolimus or everolimus using 21-day cycles.

Main Outcomes and Measures

Safety and response. When available, archived tissue was evaluated for aberrations in the PI3K pathway.

Results

Fifty-two women with metaplastic TNBC (median age, 58 years; range, 37-79 years) were treated with liposomal doxorubicin, bevacizumab, and temsirolimus (DAT) (N = 39) or liposomal doxorubicin, bevacizumab, and everolimus (DAE) (N = 13). The objective response rate was 21% (complete response = 4 [8%]; partial response = 7 [13%]) and 10 (19%) patients had stable disease for at least 6 months, for a clinical benefit rate of 40%. Tissue was available for testing in 43 patients, and 32 (74%) had a PI3K pathway aberration. Presence of PI3K pathway aberration was associated with a significant improvement in objective response rate (31% vs 0%; P = .04) but not clinical benefit rate (44% vs 45%; P > .99).

Conclusions and Relevance

Using metaplastic TNBC as a surrogate for mesenchymal TNBC, DAT and DAE had notable activity in mesenchymal TNBC. Objective response was limited to patients with PI3K pathway aberration. A randomized trial should be performed to test DAT and DAE for metaplastic TNBC, as well as nonmetaplastic, mesenchymal TNBC, especially when PI3K pathway aberrations are identified.

Results of a Phase Ib Trial of Combination Immunotherapy with a CD8+ T Cell Eliciting Vaccine and Trastuzumab in Breast Cancer Patients

BACKGROUND

CD8+ T cell-eliciting vaccines are being investigated in breast cancer patients. Preclinical data showed that trastuzumab increases the susceptibility of tumor cells to lysis by vaccine-generated CD8+ T cells, suggesting potential benefit of a combination immunotherapy strategy. The current trial was undertaken to demonstrate the safety of this approach.

METHODS

This study was designed as a dose-escalation trial enrolling clinically disease-free, human leukocyte antigen A2+ or A3+ , human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients. Patients received 6-monthly inoculations of GP2+ granulocyte-macrophage colony-stimulating factor (GM-CSF) administered concurrently with standard-of-care trastuzumab. Local and systemic toxicity, as well as left ventricular ejection fraction (LVEF) were monitored. Immunologic responses were assessed in vivo by measuring the local reaction and in vitro using an interferon-γ enzyme-linked immunosorbent spot (ELISPOT) assay.

RESULTS

Seventeen disease-free breast cancer patients were vaccinated. There were no dose-limiting or grade 3-5 local or systemic toxicities, and the median LVEF was unchanged from baseline after vaccination. Mean local reaction at initial inoculation was 28 ± 10 mm, increasing to 68 ± 8 mm at the final inoculation (p < 0.01). Mean ELISPOT response to GP2 increased from 47 ± 19 at baseline to 144 ± 60 (p = 0.13) after vaccination. Based on safety and immunologic data, the appropriate dose was determined to be 1000 μg of GP2 + 250 μg of GM-CSF.

CONCLUSION

The GP2 + GM-CSF vaccine is safe and stimulates an immunologic response when administered concurrently with trastuzumab. An ongoing phase II trial is evaluating the efficacy of combining a CD8 T-cell-eliciting vaccine with trastuzumab in HER2-positive breast cancer patients.

Abstract OT2-01-14: Triple-negative first-line study: Neoadjuvant trial of nab-paclitaxel and atezolizumab, a PD-L1 inhibitor, in patients with triple negative breast cancer (TNBC) (NCT02530489)

BACKGROUND: TNBC has an especially poor prognosis in patients (pts) whose tumor does not respond to anthracycline and taxane-based chemotherapy. Approximately 50% will have chemo-insensitive disease (CID) resulting in extensive residual disease at the time of surgery. 40-80% of these pts will recur &lt; 3 years. Recently developed molecular profiling techniques to identify TNBC subsets detect distinct molecular hallmarks. We designed a clinical trial to identify and characterize CID (ARTEMIS: A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival). Treatment naïve pts with localized TNBC undergo a pretreatment biopsy followed by anthracycline-based chemotherapy (AC). During AC the molecular profile is determined; these results along with the response assessment (clinical exam/diagnostic imaging) will identify CID and guide the second phase of neoadjuvant chemotherapy. Tumor-infiltrating lymphocytes (TIL) have been identified as having prognostic and predictive significance in TNBC pts leading to higher pCR rates post NACT. However, the tumor microenvironment also contains regulatory T cells and myeloid-derived suppressor cells that are immunosuppressive. Programmed death ligand 1 (PD-L1) is expressed in 20% TNBC. Targeting this may lead to a more durable response as compared to chemotherapy alone.

PRIMARY OBJECTIVE: Evaluate the rate of pathologic complete response (pCR)/RCB-0 + residual cancer burden (RCB)-I responses in TNBC pts, determined to have CID after anthracycline-based chemotherapy, then treat with atezolizumab + nab-paclitaxel preoperatively.

TRIAL DESIGN AND STATISITCAL METHODS: Pts deemed to have CID on the ARTEMIS trial can enter this non-randomized phase II study. Pts without response to their initial chemotherapy cycles have a low likelihood (5%) of achieving pCR with additional cycles of chemotherapy. It would be clinically meaningful for pCR to improve to 20%. Counting pCR (RCB-0) or RCB-I as response given similar survival outcomes, a two-stage Gehan-type design will be employed with 14 pts in the first stage. If at least one pt responds, 23 more will be added. This design has a 49% chance of terminating after the first stage if the true response rate is 0.05, 23% chance if the true rate is 0.10, 10% if the true rate is 0.15 and 4% if the true rate is 0.20. If accrual continues to the second stage, the 95% confidence interval for a 0.20 response rate will extend from 0.10 to 0.35.

BRIEF ELIGIBILITY CRITERIA: Inclusion: localized TNBC enrolled onto ARTEMIS and determined to have CID at the time of response assessment after anthracycline chemotherapy, adequate organ, bone marrow and cardiac parameters. Exclusion: prior immunotherapy, IBC, history of autoimmune disease, HIV, Hep-B, Hep-C, active tuberculosis, pregnant.

CORRELATIVE SCIENCE: Evaluate the presence and phenotype of TIL and other immune cell populations in tumor tissue pre/post treatment; determine changes in expression of co-stimulatory and co-inhibitory molecules on tumor cells and immune cells in the microenvironment; evaluate the immune repertoire and cytokine responses in serially collected peripheral blood mononuclear cells and serum respectively.

Citation Format: Litton JK, Moulder S, Helgason T, Clayborn AR, Rauch GM, Gilcrease M, Adrada BE, Huo L, Hess KR, Symmans WF, Thompson A, Tripathy D, Mittendorf EA. Triple-negative first-line study: Neoadjuvant trial of nab-paclitaxel and atezolizumab, a PD-L1 inhibitor, in patients with triple negative breast cancer (TNBC) (NCT02530489) [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 OT2-01-14.

Abstract P2-07-09: CPM rate among individuals with breast cancer who underwent multiplex gene testing for hereditary cancer: Single institution experience

Background: Availability of multiplex gene (MPG) testing for hereditary cancer has led to increase use of panel testing versus single gene testing for hereditary cancer. These panels include high, but also moderate penetrance genes. For some of these genes, associated cancer risk and risk management guidelines do not exist. Furthermore there is a high rate of variant of unknown significant (VUS) findings in non-BRCA genes. Currently, in the absence or minimal available data, health care providers and patients are faced with important risk management decisions, especially regarding preventive surgeries, such as prophylactic mastectomy. Currently, there is no data regarding prophylactic mastectomy rate among patients with breast cancer who underwent (MPG) testing. Therefore, our aim was to evaluate the rate of contralateral prophylactic mastectomy (CPM) in a cohort of individuals who underwent multiplex gene testing. Methods: Eight hundred thirty five patients with breast cancer who underwent MPG testing between the years 2013 and 2016 were identified using Institutional Clinical Cancer Genetics Database. Patients with pathogenic, likely pathogenic variants or who had a VUS were included in the analysis. Results: Of 835 patients with a diagnosis of breast cancer; 105 (13%) had a pathogenic or likely pathogenic mutation: 29 (28%) BRCA1, 26 (25%) BRCA2, 11 (11%) ATM, 2 (2%) BARD1, 3 (3%) BRIP, 9 (9%) CHEK2, 1 (1%) MSH2, 1 (1%) NBN, 5 (5%) PALB2, 4 (4%) PTEN, 1 (1%) RAD51C, 5 (5%) TP53, 4 (4%) CDH1, 2 (2%) MUTYH, 1 (1%) PMS2, 1 (1%) APC (1). A total of 102 (12%) VUS were found. Average age of diagnosis was 44 (Range 21-81). CPM rate was 32% (n=66) for the total cohort. Twenty nine % (n=19) of patients with non-BRCA mutations, 24.2% (n=16) with VUS and 46% (n=31) with BRCA mutations opted for CPM. Conclusion: Overall 32% of breast cancer patients with germline mutations or VUS opt for CPM at our institution. The rate for CPM in non- BRCA mutations carriers is high despite no available data regarding contralateral breast cancer risk and benefit of CPM. This finding should be validated in larger cohorts, including identification of reasons behind decision for CPM in these cohorts.

Citation Format: Elsayegh N, Gutierrez Barrera AM, Kuerer HM, Hernandez ND, Litton JK, Arun BK. CPM rate among individuals with breast cancer who underwent multiplex gene testing for hereditary cancer: Single institution experience [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 P2-07-09.