Leone, José Pablo

1107 Background: Chronic stress-mediated β2-adrenergic receptor (β2-AR) signaling promotes tumor growth via immunosuppression in the tumor microenvironment (TME) in preclinical models. Blockade of β2-AR has shown higher survival benefit in patients with TNBC in observational studies compared to other breast cancer (BC) subtypes. However, the molecular and immunological features associated with ADRB2 (gene for β2-AR) gene expression in TNBC are unknown, prompting this investigation. Methods: 3,038 TNBC samples were analyzed via NGS (592-gene panel, NextSeq; WES/WTS, NovaSeq; Caris Life Sciences, Phoenix, AZ). Immune cell fractions were calculated by deconvolution of WTS: Quantiseq. TNBC ADRB2 -high(H) and ADRB2 -low(L) RNA expression were classified as above or below the 50 th percentile, respectively. Real-world overall survival (OS) was obtained from insurance claims and calculated from tissue collection to last contact using Kaplan-Meier estimates. Statistical significance was assessed using chi-square and Mann-Whitney U tests with multiple comparison adjustments (q < 0.05). Results: ADRB2 gene expression was lowest in TNBC (median (TPM: 1.6) compared to N = 453 HR-HER2+ (1.9), N = 629 HR+HER2+ (2.0) and N = 4,918 HR+HER2- (2.2) BC (all q < 0.05). African American or Black patients (N = 670) had lower expression of ADRB2 compared to European American or White (N = 1,412) TNBC patients (1.3 vs 1.7, q < 0.05). ADRB2 -H TNBC had higher mutation frequency of PIK3CA (21% vs 15.4%), CDH1 (7% vs 3.5%), NF1 (8% vs 4%), AKT1 (3.5% vs 2.1%), but lower frequency of TP53 (81.6% vs 87.5%), NOTCH1 (2.5% vs 4.5%) and NOTCH3 (4.4% vs 11.7%) compared to ADRB2 -L, all q < 0.05. ADRB2 -H had greater PD-L1 (22C3) positivity (39.1% vs 30.2%, q < 0.05), higher % of B cells (4.5 vs 3.4), M1 Mφ (3.4 vs 2.8), M2 Mφ (3.9 vs 2.2), Tregs (2.2 vs 1.3), NK cells (3.1 vs 2.6), DC (3.1 vs 2.9), CD8 + T cells (0.9 vs 0.2), all q < 0.05. ADRB2 -H TNBC had higher T-cell inflamed score (95 vs -80), IFN γ score (-0.23 vs -0.37), MAPK activation score (-0.46 vs -1.7), all q < 0.05; and higher expression of immune checkpoint genes ( CD274, PDCD1, PDCD1LG2, CTLA4, LAG3, HAVCR2, FOXP3, IDO1, TNFSF14, TIGIT, BTLA, CEACAM1, CD47, CD274 ; fold change: 1.6-3.7, all q < 0.05). ADRB2 -H tumors had higher expression of genes related to inflammatory response, IFNγ response, IL6-JAK-STAT3 signaling (normalized enrichment score (NES): 1.9 – 2.1), while ADRB2 -L had enrichment of MYC targets V1, MYC targets V2, E2F targets and G2M checkpoint (NES: 2.5 – 4.2), all FDR < 0.01. ADRB2 -H TNBC had better OS (mOS: 23.6 vs 18.6 months; HR 0.81, 95% CI 0.73-0.89, p < 0.0001) compared to ADRB2 -L. Conclusions: High ADRB2 expression in TNBC is associated with better survival and an immune enriched TME, elevated immune checkpoints and other targetable vulnerabilities. Future studies are needed to investigate ADRB2 as a potential stress biomarker and therapeutic target.

1106 Background: TNBC, although an aggressive breast cancer (BC) subtype, is highly immunogenic and the only BC subtype where the ICI pembrolizumab is approved. However, predictive biomarkers for pembrolizumab benefit are limited. The chemokines CXCL9 and CXCL10 attract CD8 + T cells into the tumor microenvironment (TME) and are associated with chemotherapy benefit, but little is known about their role in prediciting pembrolizumab benefit in TNBC. We investigated the association of CXCL9 , CXCL10 and their cognate receptor CXCR3 with TME and ICI efficacy. Methods: 3,038 TNBC samples were analyzed via NGS (592-gene panel, NextSeq; WES/WTS, NovaSeq; Caris Life Sciences, Phoenix, AZ). Tumor mutational burden (TMB) totaled somatic mutations per tumor (high > 10 mt/MB). Immune cell fractions were estimated using WTS deconvolution (Quantiseq). CXCL9 / CXCL10 / CXCR3 -high (H) and -low (L) tumors were classified by RNA expression above or below the 50th percentile. Real-world overall survival (OS) was derived from insurance claims and calculated from start of pembrolizumab to last contact using Kaplan-Meier. Statistical significance was assessed using chi-square and Mann-Whitney U with multiple comparison adjustments (q < .05). Results: TNBC expressed higher levels of CXCL9 and CXCL10 (median (TPM): 5.3 and 14.7) compared to N = 1,082 HER2+ (4.8 and 10.3, p < 0.05) and N = 4,918 HR+HER2- (2.7 and 7, q < .05) BC. CXCR3 expression was higher in TNBC compared to HR+HER2- (1.9 vs 1.7, q < .05), but no difference when compared to HER2+ (1.9 vs 2, q = 0.97) BC. CXCL9 / CXCL10 / CXCR3 -H TNBC had higher median OS post pembrolizumab [ CXCL9 -H vs -L: 26.5 vs 15.7 months (mo), HR: 0.65 (95% CI 0.5-0.84); CXCL10 -H vs -L: 26.0 vs 20.6 mo, HR 0.74 (0.57-0.95); CXCR3 -H vs -L: 32.6 vs 18.3 mo, HR 0.68 (0.52-0.88), all p < 0.05 ]. CXCL9 -H, CXCL10 -H and CXCR3 -H had higher PD-L1 positivity (22C3), TMB high, higher T cell inflamed score, TP53 mutations, elevated B and CD8 + T cells infiltration, but not neutrophils, and higher expression of immune checkpoint genes (Table). Conclusions: High CXCL9 / CXCL10 / CXCR3 expression is associated with longer survival in patients with TNBC post pembrolizumab, and characterized by an immune-enriched TME. Further investigation is needed to evaluate this chemokine axis in TNBC and its potential as a therapeutic target to enhance ICI efficacy. TME characteristics by CXCL9, CXCL10 and CXCR3 expression. CXCL9 CXCL10 CXCR3 High Low q-value High Low q-value High Low q-value PD-L1 % 54 14 <.05 54 14.7 <.05 49 19 <.05 TMB high % 14.3 8 <.05 12.6 9.7 <.05 12.4 9.8 <.05 B cell (median %) 4.4 3.5 <.05 4.3 3.6 <.05 5 3.4 <.05 CD8+T cell (median %) 1.2 0 <.05 1 0 <.05 1.3 0 <.05 Neutrophil (median %) 4.2 4.5 <.05 4.2 4.4 <.05 4.2 4.3 0.2 T cell inflamed score 100 -84 <.05 98 -84 <.05 108 -100 <.05 CTLA4 (median TPM) 3.2 0.7 <.05 3 0.8 <.05 3.4 0.7 <.05 LAG3 (median TPM) 6.6 2.1 <.05 6.9 2 <.05 6.8 2 <.05 TP53 mutation % 88 81 <.05 90.5 78.6 <.05 86 83 0.08

1051 Background: Hispanics or Latinos (HL) and African Americans or Black (AA) have a higher prevalence of advanced-stage breast cancer (BC) at diagnosis compared to Non-Hispanic Whites (NHW). To understand the role of immune system, we evaluated the tumor immune microenvironment (TIME) by race/ethnicity among HL, AA, and NHW BC patients. Methods: 15544BC samples were tested by NGS (592, NextSeq; WES, NovaSeq) and WTS (NovaSeq; Caris Life Sciences, Phoenix, AZ). Race/ethnicity data is self-reported. Immune cell were estimated using WTS deconvolution (Quantiseq). Gene expression profiles were analyzed for T-cell inflammation score (TIS) and interferon-gamma (IFN-gamma) score. Real-world overall survival (OS) was obtained from insurance claims and calculated from date of tumor biopsy to last contact using Kaplan-Meier estimates. Statistical significance was determined by chi-square and Mann-Whitney U test with p -values adjusted for multiple comparisons (q < .05). Results: 7170 NHW (35.3%, N = 2528) biopsied (bx) from primary breast cancer (pBC), 64.7% (N = 4642) metastatic bx (mBC), 1,508 AA (pBC 39.3% N = 592, mBC 60.7% N = 916), and 1,754 HL (pBC 44.1% N = 774, mBC 55.9% N = 980) cases were included. By subtype, there were 1,956 (60.4% NHW, 20.7% NHB, 18.9% HL) TNBC, 3425 HR+/HER2- (72.6% NHW, 11.9% NHB, 15.6% HL), and 694 HER2+ (64.6% NHW, 15.7% NHB, 19.7% HL). Across all cases, AA (20.5%) and HL (20.4%) had greater incidence (%) of PD-L1+ cases versus (vs) NHW (17.4%), all q < .05. TMB-High (³10 mut/Mb) was similar in NHW (11.5%), AA (10.8%), and HL (10.9%). AA tumors had lower median % cell infiltration of M2-like macrophages (M2 Mφ), B cells, and neutrophils vs NHW (Table). HL had a lower fraction of M2 Mφ and higher CD8+ T cells (Table). AA had lower TIS (-8 vs 1, p = .02) while HL had lower IFN-gamma (-0.38 vs. -0.35, q < .05) vs NHW. By subtype, AA had lower neutrophils (4% vs 4.3%) and increased DC fractions (3.1% vs 2.8%) in TNBC vs NHW, all q < .05; no significant changes seen in HL vs NHW. AA had worse mOS than NHW overall (31.8 vs 36.8 months (mo)), HR 1.1, 95% CI 1 – 1.2, p = < .01), in pBC (40.3 vs 49.9 mo, HR 1.3, 95% CI 1.1 – 1.5, p = < .01), but not mBC (27.4 vs 29.1 mo, HR 1, p = 0.2). HL had similar mOS vs NHW overall (37.4 vs 36.8 mo, HR 0.9, p = 0.9) and in mBC (29.1 vs 31 mo, HR 0.96, p = 0.4), but worse mOS in pBC (44.7 vs 50.0 mo, HR 1.1, 95% CI 1 – 1.3, p = .01). Conclusions: Our study shows worse mOS in AA and HL pBC cases vs NHW, possibly from a less inflamed TIME in AA and HL and lower fraction of neutrophils and M2 Mφ despite higher % of PD-L1+. Targeting Mφ and CD8+ T cells and converting cold to hot TIME may lessen race/ethnic disparities, especially in early-stage BC. Immune cell fraction of NHW, AA and HL BC. NHW (median %) AA (median %) HL (median %) q-valueNHW vs AA q-value NHW vs HL B cell 5.2 4.8 5.0 <.05 0.7 DC 2.6 2.7 2.6 0.08 0.4 M1 Mφ 2.5 2.4 2.4 0.4 0.9 M2 Mφ 4.6 3.7 4.2 <.05 <.05 Neutrophils 3.7 3.5 3.4 <.05 <.05 NK cell 2.9 2.9 2.9 0.7 0.6 CD8+ T cell 0.1 0.15 0.26 0.8 <.05 Treg 1.5 1.5 1.6 0.6 <.05

TPS632 Background: Male breast cancer is a rare disease, and most cases are hormone receptor-positive (HR+). Due to a lack of clinical trials, male breast cancer has historically been treated based on data extrapolated from women. However, there are substantial knowledge gaps in the comparative efficacy, safety, and patient-reported outcomes of endocrine therapies for male breast cancer. While tamoxifen is the current standard of care, additional data are warranted for aromatase inhibitors (AI), gonadal suppression, and cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. Methods: This is an open-label, multicenter, randomized, phase II trial designed to evaluate different endocrine therapies in men with HR+ and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. A total of 60 men will be enrolled across nine (9) sites within the Translational Breast Cancer Research Consortium (TBCRC). Key eligibility criteria include male sex and stage I, II, or III HR+/HER2- breast cancer before surgical resection of the primary tumor and axillary nodes. Key exclusion criteria include prior anti-cancer therapy for the current breast cancer or any other malignancy within the past 12 months, and inflammatory breast cancer. The trial has two phases. The first phase is a window of opportunity component in which newly diagnosed men are randomized 1:1:1 to either tamoxifen (Arm A), anastrozole (Arm B), or anastrozole plus degarelix (Arm C) given for three weeks. The primary endpoint for the window phase is Ki-67 reduction from the baseline diagnostic biopsy to the research biopsy at the end of the window phase. The second phase consists of neoadjuvant treatment, in which the tamoxifen group is randomized 1:1 to tamoxifen (Arm D) versus tamoxifen plus abemaciclib (Arm E), and the anastrozole alone (Arm B) and anastrozole plus degarelix (Arm C) groups are merged and then randomized 1:1 to anastrozole plus degarelix (Arm F) versus anastrozole plus degarelix plus abemaciclib (Arm G). The duration of the neoadjuvant phase is four (4) months, and the primary endpoint of this phase is residual cancer burden (RCB) index at time of surgery. The trial is powered for the RCB endpoint in a 2 x 2 factorial design to detect a 0.6 unit decrease in RCB index with 80% power and alpha=10%. For the Ki-67 endpoint, we assume an approximately 50% reduction in Arms A and B; Arm C will be of interest if it leads to ≥80% reduction in Ki-67. Secondary endpoints include: estradiol and testosterone levels at baseline, end of window, and during neoadjuvant phase; preoperative endocrine prognostic index (PEPI) score at surgery; adverse events; and patient-reported outcomes (including quality of life). Tumor tissue will be collected for correlative analyses. The study opened to enrollment at Dana-Farber in October 2023, and additional sites will open in 2024. Clinical trial information: NCT05501704 .

Abstract Background: Breast cancer (BC) in males represents a rare clinical entity, accounting about 1% of all breast malignancies diagnosed every year. Emerging evidence suggest that a gender medicine approach is critical in the research and treatment of cancer, based on the possibility that sex hormones, molecular differences, immune system, and other factors might play a crucial role in disease management. Here, we characterized molecular and immune differences between male BC (MaBC) and female BC (FeBC) across BC subtypes. Methods: 10,728 BC samples (male, n=137; female, n=10591) were analysed by next-generation sequencing (592, NextSeq; WES, NovaSeq), Whole Transcriptome Sequencing (WTS; NovaSeq) (Caris Life Sciences, Phoenix, AZ). Tumor mutational burden (TMB) totaled somatic mutations per tumor (high ≥10 mt/MB). Microsatellite-instability (MSI) was tested by IHC and NGS. Immune cell fractions were calculated by deconvolution of WTS: Quantiseq. Real world treatment-associated survival was extracted from insurance claims and calculated from sample collection to last contact using Kaplan-Meier estimates. Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q &lt; 0.05). Results: MaBC represented higher HR+/HER2+ (6.61% vs 4.76%), HR+/HER2- (80.17% vs 60.66%) and lower HR-/HER2+ (1.65% vs 3.5%), TNBC (11.57% vs 31.08%) molecular subtypes compared to FeBC. Compared to HR+/HER2+ FeBC, MaBC had higher frequency of CHEK2, RAD51B, TSC1 mutation (Table 1) and RARα (100% vs 13.61%), DAXX (10% vs 0.16%) copy number alteration (all p &lt; 0.05). HR+/HER2- MaBC had higher frequency of BRCA2, FOXA1, CREBBP, FLCN mutation (Table 1), and FGF3 (21.62% vs 14.31%), MRE11 (1.75% vs 0.23%), MEN1 (1.75% vs 0.13%) copy number alteration, but lower frequency of TP53, CHD1, ESR1 and AKT1 mutation (Table 1) (all p &lt; 0.05). HR-/HER2+ MaBC had higher frequency of BRCA1 (p &lt; 0.05) mutation (Table 1). Male TNBC had higher frequency of CDKN2A, KMT2D, STK11, ASXL1, MYC, NF2, PPM1D, WT1, EPHA2, AMER1, ARHGAP35 mutation (Table 1) and BCL6 (4.35% vs 0.05%) copy number alteration, but lower frequency of TP53 mutation (all p &lt; 0.05) (Table 1). MaBC had higher AR protein expression (82.5% vs 60%) but lower frequency of fusion variant-AR (0.7% vs 3.9%) (all p &lt; 0.05) compared to FeBC. There was no difference in TMB high (7.1% vs 8.4%, p = 0.5) and dMMR/MSI-H (1.8% vs 0.8%, p = 0.1). Analysis of inferred immune cell infiltrates showed that MaBC had increased immune cell infiltration of B cells (5.8% vs 5.3%) and M2 Mφ (4.9% vs 4.3%), but decreased infiltration of DC (2% vs 2.6%) (all p &lt; 0.05). MaBC had increased expression of MHC class II gene HLA-DQB2 (FC: 1.3), but decreased expression of immune-related genes CD274 (FC: 1.2), IDO (FC: 1.4), IL1A (FC: 1.3) and IL12A (FC: 1.5) (all p &lt; 0.05). Correlative analyses with survival will be presented at the meeting. Conclusions: These data indicate that MaBC has a differential mutational frequency, copy number alteration, immune gene expression and immune cell infiltration and overall survival compared to their FeBC counterparts. A better understanding of these sex-based differences with additional research may help inform disease outcomes, provide a rationale for tailored therapeutic approaches and design future treatments. Table 1. Mutation frequency in male and female breast cancer Citation Format: Dario Trapani, Sachin Deshmukh, Sharon Wu, Joanne Xiu, Phil Walker, Pooja Advani, Nancy Lin, Giuseppe Curigliano, Stephanie Graff, Chadi Nabhan, George Sledge Jr, Sara Tolaney, Jose Leone. Molecular and immunological landscape of sex-based differences in breast cancer: a distinct disease in men [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS13-09.

Abstract Background: Triple-negative breast cancer (TNBC) is a heterogeneous disease and characterized by poor outcomes with a lack of targeted therapies. A comprehensive analysis of the molecular and immune landscape of invasive ductal TNBC can help improve our understanding of TNBC biology and identify novel targets and/or pathways for better management of this disease. Here, we characterized the molecular and immune signature of invasive ductal (ID) TNBC. Methods: 13,036 BC samples (ID TNBC, n=392; ID non-TNBC, n=927) were analyzed by NGS (592, NextSeq; WES, NovaSeq), WTS (NovaSeq) (Caris Life Sciences, Phoenix, AZ). A total of 10 pro-apoptotic (BAX, BAK1, BID, BAD, BIK, BCL2L11, BMF, HRK, PMAIP1, BBC3) and 6 anti-apoptotic (BCL2, BCL2L1, BCL2L2, MCL1, BCL2A1, BCL2L10) BCL2 family genes were analyzed. Immune cell fractions were calculated by deconvolution of WTS: Quantiseq. Real world overall survival (OS) and treatment-associated survival was extracted from insurance claims and calculated from tissue collection or treatment start to last contact using Kaplan-Meier estimates. Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q &lt; 0.05). Results: ID TNBC had a higher frequency of TP53, RB1, NF1, PIK3R1, NOTCH1, CREBBP, BRCA1, FANCI, and HRAS mutations (Table 1), NOTCH2 (4.3% vs 0.47%), EGFR (3.4% vs 0%), NFIB (4% vs 0.6%), MYB (3.5% vs 0.5%), CCNE1 (4.4% vs 1.1%) and AKT2 (2.4% vs 0.3%) copy number alterations, and NOTCH2 (1.6% VS 0.2%) fusion (all p &lt; 0.05) compared to invasive ductal non-TNBC. Analysis of inferred immune cell infiltrates showed that ID TNBC had increased infiltration of Tregs (2% vs 1.7%), DC (3.2% vs 2.4%), CD8 T cells (0.5% vs 0.1%), and M1 macrophages (M) (3.4% vs 2.9%), but decreased infiltration of B cells (4.5% vs 6%) and M2M (2.9% vs 4.5%) (all p &lt; 0.05). ID TNBC had increased T cell inflamed score (23 vs -9, p &lt; 0.05), IFNy score (-0.24 vs -0.34, p &lt; 0.05), MHC class I genes (HLA-A, HLA-B, TAP1, TAP2, FC: 1.1-1.5, all p &lt; 0.05), immune checkpoint genes (CD274, PDCD1, CTLA4, PD-L2, FOXP3, IDO, FC: 1.1-2, all p &lt; 0.05) and PD-L1 protein expression (SP142: 49.8% vs. 28.4%; 22c3: 41.7% vs. 16.8%, all p &lt; 0.05). ID TNBC had differential expression of BCL2 family genes (upregulation: BAK1, BID, MCL1, BCL2A1, BCL2L10, FC: 1.1-2.0; downregulation: BAD, BIK, BBC3, BCL2, BCL2L1, BCL2L2, FC: 1.2-2.8, all p &lt; 0.05) compared to invasive ductal non-TNBC. ID TNBC was associated with worse OS compared to ID non-TNBC (mOS: 24.5 vs 54.6 months; HR: 0.5, 95% CI 0.47-0.57; p &lt; 0.00001) but trend towards better survival with pembrolizumab (mOS: 29.4 vs 8.8 month; HR: 0.67, 95% CI 0.28-1.5; p=0.3) treatment. No significant OS difference was noted for by high vs. low pro and anti-apoptotic BCL2 genes except for anti-apoptotic BCL2A1 (higher expression associated with better OS (mOS: 5.7 months, HR: 0.78, 95% CI 0.6-0.99; p=0.047). Conclusion: These data indicate that ID TNBC is associated with distinct mutational profile compared to non-TNBC, has increased T cell inflamed score, IFNy score, MHC class I and immune checkpoint gene expression, and differential immune cell infiltration. Interestingly, TNBC was associated with increased M1 and decreased M2M. There is evidence to suggest that transcriptomically defined M1 high tumors are clinically aggressive and have worse OS in TNBC. BCL2 family genes are not prognostic for TNBC outcomes except BCL2A1, which needs further prospective validation. Table 1: Mutation frequency in invasive ductal TNBC and invasive ductal non-TNBC Citation Format: Pooja Advani, Sachin Deshmukh, Sharon Wu, Jacob Andring, Joanne Xiu, Alex Farrell, Jose Leone, Priya Jayachandran, Stephanie Graff, Matthew Oberley, George Sledge Jr, Asher Chanan-Khan. Comprehensive Molecular and Immunological Characterization of Invasive Ductal Triple-Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-24-01.

Abstract Background: Triple-negative invasive lobular carcinoma (TN-ILC) is a rare (0.1-1.4%) breast cancer with prognosis worse than ER positive ILC. Currently there are no targeted therapies or clinical trials specifically for TN-ILC. A comprehensive analysis of the molecular and immune landscape can help identify novel targets and pathways for TN-ILC to improve patient outcomes. Here, we characterized the molecular and immune signature of TN-ILC. Methods: 11,760 breast cancer samples (Invasive ductal (ID) TNBC, n=364; TN-ILC, n=31) were analyzed (592, NextSeq; WES, NovaSeq), (WTS; NovaSeq) (Caris Life Sciences, Phoenix, AZ). Tumor mutational burden (TMB) totaled somatic mutations per tumor (high ≥10 mt/MB) was tested by NGS. Microsatellite-instability (MSI) was tested by NGS. Immune cell fractions were calculated by deconvolution of WTS. Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q &lt; 0.05). Results: TN-ILC had higher frequency of CDH1 (0.83% vs. 66.67%), ERBB2 (0.84% vs.28.57%), ARID1A (1.65% vs. 23.33%), CBFB (0.55% vs.16.67%), AKT1 (2.22% vs.16.13%) and KMT2C (3.83% vs.13.79%), but lower frequency of TP53 (89.7%5 vs. 38.71%) mutations (all p&lt;0.05) compared to ID-TNBC. TN-ILC had higher frequency of TMB high (23.3% vs. 5.2%, p&lt;0.05) but there was no difference in dMMR/MSI-H (0% vs 1.1%, p=1). TN-ILC had higher AR RNA (FC: 14.2), protein expression (80.6% vs. 24.8%) and higher frequency of fusion variant-AR (16.1% vs 4.9%) (all p &lt; 0.05) compared to ID-TNBC. Analysis of inferred immune cell infiltrates showed that TN-ILC had higher infiltration of M2 macrophages (5.34% vs. 2.94%) and neutrophils (4.83% vs. 2.65%) but lower infiltration of M1 macrophages (3.46% vs 2.17%) and CD8 T cells (0.58% vs. 0.11%) (all p&lt;0.05). TN-ILC had lower T cell inflamed signature (16.1% vs 35.7%, p&lt;0.05), decreased immune checkpoint genes (CD274, CTLA4, FOXP3, LAG3, IDO, FC: 1.2-2.7, all p &lt; 0.05), PD-L1 protein expression (SP142: 30.4% vs. 50.2%, p=0.06; 22c3: 15.4% vs. 42.6%, p = 0.05) and differential expression of BCL2 family genes (upregulation: BIK, FC: 2.2; downregulation: BAX, BAK1, BID, PMAIP1, MCL1, BCL2A1, BCL2L10, FC: 1.0-6.3, all p &lt; 0.05) compared to ID-TNBC. Conclusion: These data suggest that TN-ILC had higher frequency of CDH1, ERBB2, AKT1, ARID1A mutations, higher M2 macrophages and neutrophils and lower M1 macrophages and CD8 T cells infiltration and, lower T cell inflamed signature. High TMB and AR expression can translate into use of immunotherapy (ICI) and AR antagonists in these patients. Additonal analysis to determine the optimal biomarker for ICI response in TN-ILC is needed. Results of our study need to be validated in larger studies with survival correlation. Citation Format: Pooja Advani, Sachin Deshmukh, Sharon Wu, Jacob Andring, Joanne Xiu, Jose Leone, Priya Jayachandran, Stephanie Graff, Mathew Oberley, George Sledge, Asher Chanan-Khan. Comprehensive molecular and immune profiling of triple negative invasive lobular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7037.

Abstract Introduction Prospective data about quality of life (QoL) in men with breast cancer (BC) are lacking. A prospective registry (EORTC10085) of men with all BC stages, including a QoL correlative study, was performed as part of the International Male Breast Cancer Program. Methods Questionnaires at BC diagnosis included the EORTC QLQ-C30 and BR23 (BC specific module), adapted for men. High functioning and global health/QoL scores indicate high functioning levels/high QoL; high symptom-focused measures scores indicate high symptoms/problems levels. EORTC reference data for healthy men and women with BC were used for comparisons. Results Of 422 men consenting to participate, 363 were evaluable. Median age was 67 years, and median time between diagnosis and survey was 1.1 months. A total of 114 men (45%) had node-positive early disease, and 28 (8%) had advanced disease. Baseline mean global health status score was 73 (SD: 21), better than in female BC reference data (62, SD: 25). Common symptoms in male BC were fatigue (22, SD: 24), insomnia (21, SD: 28), and pain (16, SD: 23), for which women’s mean scores indicated more burdensome symptoms at 33 (SD: 26), 30 (SD: 32), and 29 (SD: 29). Men’s mean sexual activity score was 31 (SD: 26), with less sexual activity in older patients or advanced disease. Conclusions QoL and symptom burden in male BC patients appears no worse (and possibly better) than that in female patients. Future analyses on impact of treatment on symptoms and QoL over time, may support tailoring of male BC management.

Abstract Many factors contribute to the poor survival of malignant brain tumor patients, some of which are not easily remedied. However, one contributor to the lack of progress that may be modifiable is poor clinical trial accrual. Surveys of brain tumor patients and neuro-oncology providers suggest that clinicians do a poor job of discussing clinical trials with patients and referring patients for clinical trials. Yet, data from the Cancer Action Network of the American Cancer Society suggest that most eligible oncology patients asked to enroll on a clinical trial will agree to do so. To this end, the Society for Neuro-Oncology (SNO) in collaboration with the Response Assessment in Neuro-Oncology (RANO) Working Group, patient advocacy groups, clinical trial cooperative groups, including the Adult Brain Tumor Consortium (ABTC), and other partners are working together with the intent to double clinical trial accrual over the next 5 years. Here we describe the factors contributing to poor clinical trial accrual in neuro-oncology and offer possible solutions.