Abstract P3-08-07: Distinct biological signatures describe differences in BRCA mutated subgroups

Background: BRCA mutated (BRCA+) breast cancers are expected to have increased activation of Homologous Recombination Deficiency (HRD) and altered DNA damage repair pathways when compared to BRCA wildtype (BRCA-). To better understand differences in these populations, biological patterns and immune responses to BRCA+ breast cancers were evaluated. The primary aim of our study was to use novel gene expression tools to assess early stage breast cancers with and without germline BRCA mutations, and within distinct BRCA+ subgroups.

Methods: We identified 124 early stage untreated breast cancers with and without BRCA mutations (n = 62 and 62, respectively). Our BRCA- group was matched by hormone receptor (HR) status, age, and stage to the BRCA+ group. The NanoString Breast Cancer 360 panel was applied to RNA isolated from 80 breast tumors (BRCA+ = 39; BRCA- = 41). The BRCA+ group had a BRCA1+ subgroup (n=17) and a BRCA2+ subgroup (n=22).

Results: There was a significant increase in two BC360 signatures in both the BRCA1+ and BRCA2+ tumors compared with the BRCA- population: Prosigna™Risk of Recurrence (ROR) score [BRCA1+: HR: 1.142 (95% CI 1.019, 1.279), p=0.02; BRCA2+: HR: 1.321 (95% CI 1.190, 1.466), p<0.001] and HRD [BRCA1+: HR: 3.576 (95% CI 2.174, 5.880), p=0.02; BRCA2+: HR: 1.801 (95% CI 1.142, 2.840), p<0.001]. BRCA1+ tumors had lower expression of ESR1 [p=0.03], PGR [p=0.02], ER signaling [p<0.001], and differentiation [p=0.005]; while BRCA2+ tumors had lower expression of stroma markers [p=0.02] and inflammatory chemokines [p=0.001]. The two BRCA+ subgroups had distinct molecular subtype correlation trends that were highly significant. BRCA1+ tumors were positively associated with a basal subtype [p<0.001], whereas this association was not significant for BRCA2+ tumors. BRCA2+ tumors were associated with an increase in luminal B subtype [p=0.05]. All BRCA+ tumors had a decrease in luminal A subtype correlation [BRCA1+: p<0.001; BRCA2+: p=0.002]. In addition to the BC360 signatures, a differential analysis of all genes in the BC360 panel revealed more single gene differences in BRCA2+ than BRCA1+ tumors when compared to BRCA- tumors.

Conclusions: In early stage BRCA+ breast cancer, tumors have higher ROR and increased HRD signature scores compared to BRCA- tumors. Furthermore, BRCA1+ and BRCA2+ tumors have both signature and single gene expression differences when compared to BRCA- tumors, indicating distinct subgroup-related biology. The greater correlation of BRCA1+ tumors with basal-like biology and BRCA2+ tumors with aggressive hormonal biology confirms these trends. Distinctions in hormone receptor signaling, DNA-damage pathways, and microenvironment/inflammatory features between BRCA1 and BRCA2 associated cancers suggest a need for different prevention and therapeutic strategies for each of these breast cancer subtypes. The unique biological patterns identified here should be further evaluated as predictive or prognostic tools that could be translated into clinical care for early stage BRCA+ patients.

Citation Format: Force J, Plichta J, Stashko I, Kimmick G, Westbrook K, Sammons S, Hwang S, Hyslop T, Kauff N, Castellar E, Nair S, Weinhold K, Davis S, Mashadi-Hossein A, Brauer HA, Marcom PK. Distinct biological signatures describe differences in BRCA mutated subgroups [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-07.

Abstract P2-04-19: Elucidating the tumor immune microenvironment phenotype in early stage untreated BRCA mutated breast cancer patients

Background: Increased stromal tumor infiltrating lymphocytes (TILs) are predictive and prognostic for improved outcomes from neoadjuvant or adjuvant chemotherapy in triple negative breast cancer. Increased tumor mutational burden may promote neoantigens causing immune system upregulation. Microsatellite instability in gastrointestinal cancer predicts for response to checkpoint inhibition and is associated with inherited cancer predisposition. The immune system response in BRCA mutated breast cancer has not been described. The purpose of this study is to assess tumor infiltrating immune cells in early stage breast cancer patients with and without BRCA gene mutations.

Methods: We retrospectively investigated 124 early stage breast cancer patients with BRCA mutations (n=62, BRCA+) and without BRCA mutations (n=62, BRCA WT). The %TILs was measured manually by H&E. Our control group consisted of age, stage, and receptor status matched early stage untreated breast cancer patients who were deemed BRCA WT by extended gene panel testing or were negative for BRCA 1/2 and had a posttest probability of harboring an autosomal dominant mutated gene of ≤ 1% using the Bayes-Mendel algorithm. We used a two-sample binomial arcsin approximation to detect a 20% difference in TILs between cohorts to attain 80% power with a one-side alpha of 0.05. Wilcoxon Rank-Sums test was used to compare differences in the central tendencies for continuous variables. We used the Nanostring PanCancer immune profiling panel to immunophenotype a portion of the BRCA+ and BRCA WT cohorts and used nSolver for quality control, normalization, and bioinformatics analyses.

Results: Here we report TILs from the first 21 patients of our study. Thirteen patients harbored BRCA mutations and eight patients did not. All patients were HER2 negative. Eight (61%) and four (50%) patients were hormone receptor positive (HR+) in the BRCA+ and BRCA WT cohorts, respectively. Median %TILs were not significantly different between the BRCA+ (15, range 0-70) and BRCA WT (17.5, range 5-60; p=0.7) groups. Median %TILs in the HR+/BRCA+ (12.5, range 0-50) and HR-/BRCA+ (15, range 5-70) cohorts were not statistically different when compared to HR+/BRCA WT (10, range 5-15; p=0.4) and HR-/BRCA WT (30, range 20-60; p=0.2) cohorts, respectively. There were 2 patients with lymphocyte predominant breast cancer (n=1, HR-/BRCA+; n=1, HR-/BRCA WT).

Conclusions: This is the first study to characterize TILs and a tumor immune microenvironment phenotype in early stage breast cancer patients with BRCA mutations. These results suggest harboring a BRCA mutation is not associated with increased TILs in early stage untreated breast cancer patients. This conclusion stayed true regardless of hormone receptor status. However, a trend of decreased TILs was seen in HR-/BRCA+ patients when compared to those with HR-/BRCA WT disease. Moreover, the median and range of TILs were higher in the HR+/BRCA+ group compared to the HR+/BRCA WT group. This suggests increased TILs may exist in some HR+ patients with a BRCA mutation. Further investigation of TILs and immune profiling of early stage untreated breast cancer patients with and without BRCA mutations is warranted.

Citation Format: Force J, Abbott S, Broadwater G, Kimmick G, Westbrook K, Hwang S, Kauff N, Stashko I, Weinhold K, Nair S, Hyslop T, Blackwell K, Castellar E, Marcom PK. Elucidating the tumor immune microenvironment phenotype in early stage untreated BRCA mutated breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-19.

Adherence to extracolonic cancer screening in Lynch syndrome kindreds

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Introduction: In addition to colorectal cancer (CRC), Lynch syndrome (LS) patients are at increased risk of extracolonic malignancies including endometrial (EC), ovarian (OC), upper gastrointestinal and urothelial tract cancers. Although the efficacy of extracolonic cancer screening in LS has not been clearly demonstrated, multi-organ screening is routinely recommended for LS patients (Lindor et al., JAMA 2006). Anecdotal evidence suggests that adherence to such screening may be inferior to CRC screening. Methods: 35 adults, identified in the context of genetic counseling and testing (GCT) as being from LS kindreds, were given recommendations for multi-organ screening and enrolled on a prospective follow-up study. For participants with relevant organs at risk, these included colonoscopy, urine cytology, transvaginal ultrasound (TVUS), CA-125 level and endometrial sampling all to be performed at least annually. Adherence with screening, perceived risk of cancer subtype and future intentions regarding screening were evaluated at least 12 months after GCT. Results: Median age at time of GCT was 44, 66% were female and 69% were diagnosed with a LS- related cancer prior to GCT (15 CRC; 9 EC). At time of follow-up, 89% of patients without CRC had a colonoscopy within the year. Among women at-risk for OC, 25% had TVUS and 38% had CA-125 level within the year. Among women at risk for EC, 22% had TVUS and 22% had endometrial sampling within the year. Of all participants, 40% had urine cytology within the year. Of participants with relevant organs at-risk, 72%, 33%, 75% and 12% reported their risk of developing CRC, EC, OC, and urothelial tract cancer, respectively, as “moderately”, “very” or “extremely” high. Of patients with previous colonoscopy, 93% had definitive intentions to continue on schedule screening. However, only 68%, 50%, 60% and 50% of patients who underwent previous urine cytology, TVUS, CA-125 or endometrial sampling, respectively, had definitive intentions of continuing on schedule screening. Conclusions: Adherence with extracolonic cancer screening in LS kindreds is poor and patients persistently underestimate their extracolonic risk despite GCT. Possible interventions should be aimed at better educating patients about extracolonic cancer risk and importance of on-going surveillance.

No significant financial relationships to disclose.

DNA mismatch repair protein defects and endometrial cancer in women age 40 and younger

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Background: The significance of the hereditary basis of endometrial cancer is apparent in young women with endometrial cancer. The objective of this study was to describe the incidence and prognostic implications of DNA mismatch repair protein defects in a series of patients age 40 years and younger with endometrial cancer. Methods: We performed a retrospective cohort study of patients age 40 years or less who were diagnosed with endometrial carcinoma between 1/93 and 5/08. Clinical and pathologic data were extracted from medical records. Paraffin-embedded slides from hysterectomy specimens were obtained and DNA mismatch repair (MMR) immunohistochemistry (IHC) was performed. Cases were analyzed according to presence of DNA MMR protein defects. Standard two-sided statistical tests were performed. Results: Of the 71 identified patients, the median age was 37 years (range, 24–40), with a median follow-up of 47 months (range, 1–178). The majority were of endometrioid histology (94%), stage I (73%), and FIGO grade 1 (61%). IHC was performed with available blocks (n = 56), and loss of DNA MMR was found in 9 cases (16%). Cases with loss of DNA MMR were more likely to have high-grade (FIGO 2 or 3) tumors (p < 0.001), be advanced stage (III or IV) at the time of diagnosis (p < 0.001), and have a family history suggestive of hereditary non-polyposis colorectal cancer (p = 0.01). There was no difference between the groups in histology, obesity (BMI>30), parity, or history of infertility. Analysis of clinical outcomes revealed that cases with loss of DNA MMR had significantly worse overall survival (median survival not reached, log rank p = 0.018). At the time of last follow-up, 2 (22%) patients with loss of DNA MMR were dead of disease compared with 2 (4%) patients with retained DNA MMR. Conclusions: Endometrial cancer is rare in young women age 40 years or less. In these patients, loss of DNA MMR was associated with worse clinicopathologic factors (high-grade and advanced-stage tumors) and worse outcome. Other clinical risk factors associated with endometrial cancer were not associated with loss of DNA MMR. The data suggest that MMR testing in women 40 years of age or younger with endometrial cancer may have clinically useful prognostic information.

No significant financial relationships to disclose.

Ductal carcinoma in situ and BRCA mutations: Association and risk factors

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Introduction: Ductal carcinoma in situ (DCIS) has been associated with BRCA mutations. Factors associated with the presence of mutations are not well defined. Methods: BRCA founder mutation status was determined in 3 groups of women with DCIS: 1) a prevalent convenience sample of Ashkenazi Jewish (AJ) women (Sukumvanich SSO 2005), 2) an incident cohort of AJ women ascertained before breast surgery and 3) a clinical ascertainment of probands (P) with DCIS (53 AJ and 38 non-AJ) presenting to a cancer risk assessment service. For women in groups 1 and 2, BRCA founder mutation status was also determined in age-matched controls with invasive breast cancer (BC). Results: Within the prevalent ascertainment, 3/62 (4.8%) women with DCIS and 15/130 (11.5%) controls with invasive BC had BRCA mutations. In the incident cohort, 0/58 (0%) women with DCIS and 6/116 (5.2%) controls with invasive BC had BRCA mutations (combined OR 3.6, 95% CI 1.1–12.5, p 0.04). In the clinical ascertainment of AJ women with DCIS, mutations were identified in 4/35 (11.4%) P ≤ 50 yrs at dx and in 2/18 (11.1%) P > 50 yrs. The proportion of AJ P with mutations based on family history (FH) of BC and ovarian cancer (OC) is shown in the table. In AJ P with DCIS, FH of OC is strongly associated with BRCA mutations (adjusted OR 10.0, 95% CI 1.1–89.3, p 0.04). Among non-AJ P, no mutations were identified without a FH of OC or BC ≤ 50 yrs at dx. Conclusions: DCIS is associated with BRCA mutations in AJ women, but the prevalence is lower than in women with invasive cancer. FH of OC is a strong risk factor.

[Table: see text]

No significant financial relationships to disclose.

Usage trends of minimally absorbed vaginal estrogens in breast cancer patients versus patients with non-breast malignancies

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Background: To determine if differences exist in the use of minimally absorbed vaginal estrogens in a breast cancer population versus one with non-breast malignancies. Methods: A retrospective review of all patients with documented malignancy who were prescribed vaginal 17-β-estradiol tablets (Vagifem, Novo-Disc, Princeton, New Jersey) through the General Gynecology Service from July 1, 2003 to June 30, 2004. Data were accessed from the pharmacy health information computerized system. All patients complained of dyspareunia, and examination was consistent with vaginal atrophy. Comparison between groups was performed using the Fisher Exact Test and t-test. Results: 152 patients were identified_81 patients with breast cancer diagnoses and 71 with non-breast malignancies. There was no difference in the mean age of patients in either group, 56.9 vs. 55.1 years. (p = 0.30). Overall, 60 of the 152 patients refilled their prescriptions through the time of last follow-up. There was no difference in the proportion of breast versus non-breast cancer patients who continued vaginal estradiol, 39.5% (32/81) versus 39.4% (28/71) respectively. When the cohorts were stratified by age ≤ 50 or >50 at the time of initial consultation, 79% (11/14) of breast cancer patients age ≤ 50 years refilled their prescriptions at follow-up compared to 31.3% (21/67) of patients >50 (p = 0.002). In women with non-breast malignancies there was no age-related difference in the proportion who obtained refills: 35% (7/20) ≤ 50 years versus 41.2 % (21/51) >50 years (p = 0.79). Conclusions: Minimally absorbed vaginal estrogens appear to be viewed favorably amongst the younger breast cancer patient population. The older breast cancer population does not appear to continue vaginal estradiol use long-term. This may be due to differences in relationship status, interval from menopause to diagnosis, prior exposure to estrogen, or relief of symptoms with alternative therapies. These findings are different than those observed for similar patients with non-breast malignancies. Further studies looking at the use of minimally absorbed vaginal estrogens are needed to further evaluate the usage trends in differing patient populations.

No significant financial relationships to disclose.

Treatment of menorrhagia in women undergoing hematopoietic stem cell transplantation

The management of uterine bleeding in female transplant patients over a 3-year period at our institution was reviewed. A total of 33 females who had undergone allogeneic hematopoietic stem cell transplant were identified as having received gynecologic consultation for the diagnosis of menorrhagia. Hormone therapy achieved a resolution of symptoms in 32 (97%) of the patients, and 26 (79%) required only one hormone regimen. Following resolution of symptoms, transition to standard-dose oral contraceptive pills as maintenance therapy prevented recurrent menorrhagia due to high circulating estrogen levels. Alternatives for patients who are unable to tolerate oral administration and those with hepatotoxicity are also discussed.