Advani, Pooja

Abstract Background: Women at increased risk for breast cancer (BC) may benefit from taking prevention medication (PM) with tamoxifen (tam). Historical uptake to PMs for women who qualify has been low. Recent studies have shown baby tam (5mg/day) to have similar efficacy to standard dosing (20mg/day) with lower risk for adverse events (AEs) in women with DCIS or high risk intraepithelial lesions. Herein, we aimed to evaluate uptake, adherence, and tolerability of baby tam in women at increased risk for BC and those with DCIS. Methods: Women seen at the Mayo Clinic Breast Center in Minnesota or Florida who qualified for PM due to DCIS, high risk intraepithelial lesions (IELs) including LCIS and/or AH, or with increased risk based on validated BRCAT or IBIS model calculation (BCRAT 5 year risk ≥ 3% or IBIS 10 year risk ≥ 8%) were offered participation. All women received consultation with a breast specialist for discussion of PM rationale, benefits, side effects, and risks. Patients received baseline survey to assess understanding of their risk and role for PM and then 1 year follow-up survey to assess adherence and tolerability. Results: 41 patients consented for participation and 31 of those completed follow-up at 1 year.Median age of enrollment was 49 years. After initial consultation, 90% (n=37) reported good or complete understanding of BC risk. Of the 31 patients included in 1 year follow-up, 5 patients had DCIS, 13 had high-risk IELs, and 13 qualified based on BCRAT/IBIS calculation. Seventy-four percent (n= 23) of patients reported they took baby tam after consultation. No differences in age (p=0.89), education (p=0.13), or menopause status (p=0.11) between those who did and did not take medication were seen. Those who initiated baby tam were more likely to have DCIS or high risk IEL compared to those who did not (p < 0.001). Seventy-eight percent (n=18) of those who initiated baby tam were still taking medication at 1 year follow-up. Of patients who discontinued baby tam, all cited side effects as primary reason for discontinuation, with hot flashes (n=2), night sweats (n=2), and fatigue (n=2) being most common. Patients who continued medication had higher estimated BC risk compared to those who discontinued baby tam (IBIS 10 yr risk 12.7% vs 7.6%, p = 0.027). Patients with DCIS or high risk IEL were more likely to continue medication at 1 year compared to those patients who qualified for PM based on calculated BCRAT/IBIS score (p=0.05). Only 1 patient with DCIS and 1 patient with high-risk IEL discontinued baby tam at 1 year. Conclusions: Uptake to baby tam after informed discussion in patients who qualify is high, especially in those patients with high risk IELs or DCIS. Adherence and tolerability at 1 year follow-up is improved compared with traditional dosing of tam. Qualifying criteria for patients who did and did not take baby tamoxifen after informed consultation with breast specialist Citation Format: Lauren Cornell, Sandhya Pruthi, Karthik Ghosh, Klassen Christine, Pooja Advani. Improved uptake and adherence to prevention medication with use of baby tamoxifen in patients at high risk for 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 PS07-04.

Abstract Background: Latin Americans are more likely to be diagnosed with aggressive early-stage breast cancer compared to Non-Hispanic White. Multiple factors may contribute to this, including metabolic factors and ancestry. In a previous study, we identified upregulated immune pathway genes in Luminal B tumors from obese Black patients compared to matched White patients. In this study, we report clinical and transcriptomic profiles of breast tumors from Latin and White patients to enhance understanding of factors contributing to aggressive tumor biology in Latin patients. Methods: We matched 311 Latin and 311 White breast cancer patients enrolled in FLEX by age, T stage, N stage and clinical subtype (ER/PR and HER2 status). FLEX (NCT03053193) is a prospective, observational trial that includes stage I-III breast cancer patients who receive MammaPrint (with or without BluePrint) as standard of care and consent to whole transcriptome and clinical data collection. MammaPrint is a 70-gene risk of distant recurrence signature that classifies patients as Low Risk or High Risk. BluePrint is an 80-gene molecular subtyping signature, categorizes tumors as Luminal-, HER2- or Basal-Type. MammaPrint further groups Luminal into A (Low Risk) and B (High Risk). ImPrint is a 53-gene signature that has been shown to predict the likelihood of achieving pCR with PD1-PDL1 immune checkpoint inhibitors. Statistical analyses on groups were conducted using arsenal R package and p-value < 0.05 was considered significant. Whole transcriptome comparisons were made, using limma R package, between Latin and White patients stratified by BluePrint subtype Luminal and weight categories normal (body-mass-index (BMI) 18.5 to < 25) and obese (BMI ≥30). Significant differentially expressed genes had an adjusted p-value < 0.05. Gene set enrichment analysis (GSEA) was conducted using fgsea R package. Results: Latin patients had significantly higher percentage of type 2 diabetes (23.3% vs 8.5%), BMI obese (49.0% vs 39.4%), BluePrint Basal (14.8% vs 9.3%) and ImPrint Immune Sensitive (12.0% vs 5.1%) compared to matched White patients. When comparing whole transcriptome of tumors from Latin and White patients, only tumors stratified by Luminal B and obesity resulted in differentially expressed genes: Latin patients had higher expression (>2-fold change) of 42 immunoglobulin genes compared to White, with only IGKV6-21 being statistically significant. Additional immune related genes such as IKZF1 and AGER, as well as UTS2 (gene encoding a vasoconstrictor agent and contributor of angiogenesis) were significantly upregulated in Latin patients. Upregulation of immune related pathways such as inflammatory response, interferon alpha/gamma response and downregulation of adipogenesis, oxidative phosphorylation and MYC targets were identified in Latin patients compared to White using GSEA Hallmarks gene sets. Conclusion: There were additional clinical and genomic differences between tumors from Latin and White patients, even when controlling for age, T stage, N stage and clinical subtype. Particularly, there were more type 2 diabetes, BMI obese, BluePrint Basal, and ImPrint Immune Sensitive among Latin patients. In addition, transcriptomic differences between obese Latin and matched White patients were found in Luminal B subgroup that may contribute to the aggressive tumor biology; immunoglobulin genes and immune related pathways were associated with higher expression in Latin patients. This study suggests that biological differences in breast tumors, particularly from obese patients, may result from shared background and reflects the need for inclusion of diverse patient groups in clinical trials. Citation Format: Marcela Mazo-Canola, Virginia Kaklamani, Pooja Advani, Sailaja Kamaraju, Alfredo A. Santillan-Gomez, Robert Maganini, Julie Barone, Sahra Uygun, Lavanya Samraj, William Audeh, Joyce O'Shaughnessy, FLEX Investigators' Group. Racial disparities in breast cancer and effect of obesity: MammaPrint, BluePrint and whole transcriptome analyses of tumors in Latin American patients in FLEX trial [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 PS18-04.

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 < 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 < 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 < 0.05). ID TNBC had increased T cell inflamed score (23 vs -9, p < 0.05), IFNy score (-0.24 vs -0.34, p < 0.05), MHC class I genes (HLA-A, HLA-B, TAP1, TAP2, FC: 1.1-1.5, all p < 0.05), immune checkpoint genes (CD274, PDCD1, CTLA4, PD-L2, FOXP3, IDO, FC: 1.1-2, all p < 0.05) and PD-L1 protein expression (SP142: 49.8% vs. 28.4%; 22c3: 41.7% vs. 16.8%, all p < 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 < 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 < 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: Metaplastic Breast Cancer (MBC) is rare (0.2-5%), aggressive form of BC characterized by chemotherapy resistance and has worse outcomes in comparison to other BC subtypes. Resistance to chemotherapeutic agents is related to defects in intact intrinsic apoptosis pathway and the BCL2 family of proteins are the central regulators of this pathway. Majority of MBC have triple-negative receptor status and have no standard therapeutic approach and validated prognostic markers. Here, we examine the association of BCL2 family pro-apoptotic and anti-apoptotic genes expression with metaplastic TNBC (MTNBC) patient survival. Methods: 13,036 BC samples (MTNBC, n=102; metaplastic non-TNBC, n=20) were analyzed by next-generation sequencing (592, NextSeq; WES, NovaSeq), Whole Transcriptome Sequencing (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. MTNBC with PMAIP1-high(H) and -low(L) expression was classified by top and bottom quartile, respectively. Pathway enrichment was determined by GSEA (Broad Inst). Real world overall survival (OS) was extracted from insurance claims and calculated from tissue 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 < 0.05). Results: MTNBC had enrichment of apoptosis (NES: 1.4, FDR: 0.05), glycolysis (NES: 1.48, FDR: 0.03), PI3K/AKT/mTOR signaling (NES: 1.43, FDR: 0.05), P53 (NES: 1.51, FDR: 0.06), NOTCH signaling (NES: 1.39, FDR: 0.05), TGFβ signaling (NES: 1.41, FDR: 0.05), WNTβ catenin signaling (NES: 1.41, FDR: 0.05) and IL2/STAT5 signaling (NES: 1.33, FDR: 0.09) pathways compared to metaplastic non-TNBC. MTNBC had higher expression of BCL2 pro-apoptotic genes BAX (Fold Change (FC): 1.6), BAK1 (FC: 1.3), BID (FC: 2), BAD (FC: 1.6), BCL2L11 (FC: 2.5) and BBC3 (FC: 1.5), and anti-apoptotic genes BCL2L1 (FC: 1.6) and BCL2L2 (FC: 1.3) (all p < 0.05) compared to metaplastic non-TNBC. Higher PMAIP1 gene expression was associated with worse MTNBC patient survival (mOS: 14.3 month; HR: 0.37; 95% CI 0.19-1.41; p=0.002) (Table 1), but not in metaplastic non-TNBC (mOS: Inf; HR: 1.96; 95% CI 0.64-6.02; p=0.23). PMAIP1-H MTNBC had higher expression of immune checkpoint genes CD274 (FC: 2.8), PDCD1 (FC: 2.2), TIM3 (FC: 1.8), LAG3 (FC: 2.1) and IDO1 (FC: 5.7) (all p < 0.05), compared to PMAIP1-L MTNBC. PMAIP1-H MTNBC had higher frequency of IHC-PD-L1 positivity (68.4% vs 14.3%, p < 0.05). PMAIP1-H MTNBC had higher expression of stem cell related genes CD44 (FC: 1.7), ALDH1A2 (FC: 2.2), ALDH1A3 (FC: 2.6), SOX2 (FC: 5.21) and NANOG (FC: 2.13) (all p < 0.05) compared to PMAIP1-L MTNBC. Conclusion: This is the first comprehensive analysis of expression and prognostic role of BCL2 family proteins in MBC. Our data suggest a strong association of higher expression of PMAIP1 with worse MTNBC patient survival, potentially attributed to higher immune checkpoint, stem cell-related genes expression, and higher frequency of PD-L1 positivity in PMAIP1-H tumors. These findings indicate PMAIP1 as a potential prognostic biomarker candidate in MTNBC but needs further validation in large prospective studies Table 1. Overall survival of metaplastic TNBC patient based on BCL2 family gene expression. Citation Format: Pooja Advani, Sachin Deshmukh, Sharon Wu, Jacob Andring, Joanne Xiu, Alex Farrell, Milan Radovich, George Sledge Jr, Dario Trapani, Evanthia Roussos Torres, Stephanie Graff, Asher Chanan-Khan. Comprehensive Characterization of BCL2 Family Genes in Metaplastic 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 PO4-24-02.

Abstract Background: Post-menopausal women with estrogen receptor positive breast cancer (BC) are typically prescribed endocrine therapy with an aromatase inhibitor (AI) for 5-10 years following BC diagnosis. AIs have multiple established side effects related to estrogen deprivation including vasomotor symptoms, vaginal dryness, and accelerated bone thinning. Many patients also complain about the impact of AIs on skin quality; however, limited data currently exists, particularly with objective measurements of skin quality. Canfield Sciences VISIA-CA is a device that can be used to objectively measure skin changes using patented comparison to norms analysis with a skin feature database to grade the skin relative to others in the same age and skin type. Herein, we aim to evaluate changes in skin quality with the Canfield Sciences VISIA-CA Device after initiation of AI therapy and investigate potential benefits of skincare intervention. Trial Design: This is a pilot study aiming to describe changes in skin quality after initiation of AI therapy in BC survivors through use of VISIA-CA technology and patient reported outcome measures. This study will allow us to collect data and identify the trend (if any) for a future larger study. Patients who consent for participation are given a baseline survey to assess self-reported quality of life, perception of skin quality, and self-image prior to initiation of AI. Patients also receive baseline skin measurement with the VISIA-CA device and facial skin photography. Baseline skincare regimen is documented. Any patients on prescription tretinoin products at time of baseline assessment are excluded from the study. Patients return 6 months after initiation of AI for follow-up surveys, updated VISIA-CA measurement, and facial skin photography. Patients then meet with a Mayo Clinic Cosmetic Center aesthetician for skincare intervention with recommended topical treatments including daily facial cleanser, exfoliator, toner, hydrating crème, and retinol-based product. Patients return for additional visits with updated survey, VISIA-CA measurement, and facial skin photography at 1 month, 3 months, and 6 months after skincare intervention. Patients are asked to complete skincare compliance diary to document adherence on a weekly basis. Eligibility Criteria: Post-menopausal patients with newly diagnosed ER-positive BC at Mayo Clinic Florida are identified for participation in the study prior to beginning AI therapy. Specific Aims: 1.) Evaluate the incidence and severity of skin changes after initiation of AI therapy in BC survivors through use of Canfield Sciences VISIA-CA technology, facial skin photography, and validated patient reported outcome measures. 2.) Assess for objective improvements in skin quality measurements after skincare intervention including a retinol-based product Statistical Methods: Continuous variables will be summarized as mean (standard deviation) or median (range) and categorical variables will be reported as frequency (percentage). The changes of skin measurement and patient reported outcome measurements will be calculated and summarized for the following time frames: 1) from initiation of AI therapy to 26 weeks after 2) from the initiation of skincare intervention and 4 weeks, 12 weeks, and 26 weeks after. Appropriate statistical plots will be used to illustrate the change. Target Accrual: 50 patients. Schedule of Events Citation Format: Lauren Cornell, Leila Tolaymat, Pooja Advani, Saranya Chumsri, Pincelli Thais. Enhancing skin appearance and quality of life in breast cancer survivors on aromatase inhibitor therapy [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 PO2-19-12.

Abstract Background Metaplastic breast carcinoma (MBC) is an unusual malignancy that presents a diagnostic challenge due to the presence of varying cytomorphologies that can be seen in benign and malignant tumors. We posit that metastatic disease to the breast, itself an uncommon entity, should be considered in the differential diagnosis of MBC. We report a unique case of metastatic non-small cell lung cancer (NSCLC) with an actionable driver mutation that presented as a symptomatic breast mass and was initially considered to represent MBC. Report A 74-year-old woman with a 22-pack-year smoking history presented to the breast clinic complaining of a palpable left breast mass that had grown rapidly over the previous month. Ultrasound-guided biopsy of the breast mass revealed high-grade poorly differentiated carcinoma. On immunohistochemical (IHC) evaluation, tumor cells were strongly positive for epithelial markers CAM5.2 and keratin AE1/AE3, weakly positive for breast cancer (BC) marker TRPS1, and negative for BC marker GATA3, squamous cell carcinoma markers p63 and CK5, and melanoma marker SOX10. Metaplastic triple-negative BC was diagnosed. However, concern remained for metastasis from a non-breast primary tumor due to the patient’s constitutional symptoms such as fatigue, night sweats, and 60-pound unintentional weight loss over the previous year, as well as interval development of a suspicious nodular rash on her right upper extremity. An FDG-PET-CT was obtained and demonstrated a hypermetabolic left lung consolidation (maximum SUV 33.3) measuring 7.2 cm, pulmonary nodules, and extensive thoracic lymphadenopathy. Due to rising suspicion for a primary lung tumor, additional IHC staining on the original breast biopsy was requested. Tumor cells were positive for TTF-1, consistent with metastatic lung adenocarcinoma. Tissue next-generation sequencing (NGS) identified a MET exon 14 skipping mutation, making the patient eligible for treatment with capmatinib, a first-line kinase inhibitor targeted therapy for metastatic NSCLC. At the time of this report, the patient has completed a course of palliative stereotactic body radiation therapy to the left lung and started capmatinib 400 mg BID, which she is tolerating well. Her first restaging scans after treatment initiation will be obtained one week after the time of this report. Conclusion In the absence of heightened suspicion for a non-breast primary tumor, our patient had initially received a diagnosis of triple-negative MBC. This diagnosis would have exposed her to increased treatment-related toxicities from cytotoxic chemotherapy and poor prognosis from MBC without survival benefit from targeted therapy for NSCLC. We advocate for the use of supplemental body imaging, expert and comprehensive IHC evaluation, and multidisciplinary discussion in cases of MBC and undifferentiated breast malignancy to facilitate accurate diagnosis and treatment. Citation Format: Tanmayi Pai, Marte Wasserman, Jason Lewis, Miglena Komforti, James Jakub, Augustine Lee, Yanyan Lou, Pooja Advani, Rohit Rao. Metastatic Lung Cancer Masquerading as Metaplastic 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 PO2-20-08.

Abstract Background: Activation of the RAS/MAPK pathway is associated with reduced tumor-infiltrating lymphocytes and poor outcomes in triple-negative breast cancer (TNBC). This trial evaluated the efficacy of pembrolizumab in combination with binimetinib, a MEK inhibitor. Methods: Patients with unresectable locally advanced or metastatic TNBC with ≤ 3 prior lines of therapy were enrolled. Treatment includes a 2-week run-in with binimetinib followed by pembrolizumab. There were 2 dose levels (DL) with binimetinib at 45 mg at DL 0 and 30 mg at DL -1. A standard 3+3 design was used in Phase I, and Simon’s two-stage Optimal design was used in Phase II. PD-L1 22C3 was performed in archival samples with CPS ≥ 10 considered as positive (PD-L1+). Tumor-infiltrating lymphocytes (TILs) were quantified into 0, 1, 2, and 3+. Circulating tumor cells (CTC) and circulating cancer-associated macrophage-like cells (CAML) were isolated using CellSieve microfilters and immunofluorescently labeled with PD-L1 and p-ERK. Wilcoxon rank sum test, Chi-square test, Cox regression model, and Spearman correlation were used for analysis. Results: 22 patients were enrolled with a median age of 58 years old. Dose-limiting toxicity (DLT) was observed in 2 out of 4 patients in DL 0, with grade 3 ALT abnormality, flank pain, and nausea. In the next 6 patients in DL -1, there was 1 DLT with grade 3 AST/ALT abnormality. There were 17 patients treated with DL -1 and were evaluable for response. The objective response rate (ORR) was 29.41% (95% CI: 10.31-55.9) with 1 complete response (CR) and 4 partial responses (PR). The clinical benefit rate (CBR ≥ 24 weeks) was 35.29% (95% CI: 14.21-61.67). ORR in patients without liver metastases was 55.56% (95% CI: 21.20 - 86.30) and CBR was 66.67% (95% CI: 29.93-92.51). No response was observed in all 5 patients with liver metastases. There were 40.9% of patients with PD-L1 CPS ≥ 10. ORR in patients with PD-L1+ was 80%. However, 11.1% of patients with PD-L1 negative tumors also had an objective response and 44.4% of patients had clinical benefit ≥ 24 weeks. PD-L1 expression in archival tissue was associated with ORR (p 0.032) but not CBR (p 0.198), progression-free survival (PFS, p 0.373), and overall survival (p 0.348). TILs in archival tissue were also not associated with CBR (p 0.155) and PFS (p 0.157). One patient with TILs 0 had a stable disease ≥ 24 weeks and 2 patients TILs 1+ also had an objective response. We further evaluated blood-based biomarkers with CTC and CAML. Baseline PD-L1 in CAML (p 0.04) and decline in CAML size (p 0.02) after 1 cycle was significantly associated with CBR. However, baseline CTC count, CAML count (p 0.64), CAML size (p 0.46), p-ERK in CAML (p 0.23), and changes in CTC count, CAML count (p 0.83), p-ERK (p 0.07), and PD-L1 (p 0.08) in CAML were not significantly associated with responses. Using Cox regression analysis, a reduction in CAML count (p 0.02), CAML size (p 0.01), and PD-L1 in CAML (p 0.03) were associated with significant improvement in overall survival but not the reduction in p-ERK (p 0.6). However, PD-L1 expression in CAML is not associated with PD-L1 expression in archival tissue (Spearman correlation 0.13). Conclusions: Pembrolizumab and binimetinib at 30 mg are safe with manageable toxicities. Consistent with the preclinical data that MEKi can restore T cell function, promising activity was observed even in patients with low TILs and PD-L1 negative, particularly in patients without liver metastases. PD-L1 expression in peripheral blood CAML rather than archival tumor tissue may serve as a better biomarker to predict the clinical benefit of this combination. Early reductions in CAML count and size, were also significantly associated with responses. Future larger clinical trials are warranted to further evaluate the efficacy of this chemotherapy-free combination. Citation Format: Saranya Chumsri, Joseph Larson, Daniel Adams, Kathleen Tenner, Cha-Mei Tang, Morgan Weidner, Amanda Arnold, Dana Haley, Pooja Advani, Kostandinos Sideras, Alvaro Moreno-Aspitia, Edith Perez, Keith Knutson. Phase I/II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic 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 PO3-06-14.

Abstract Background: Taxane based chemotherapy (chemo) forms a critical part of breast cancer (BC) treatment in early and metastatic settings. Taxanes can cause peripheral neuropathy (CIPN)-sensory and motor, primarily of the hands and feet, resulting in quality of life decline and negaive impact on BC survival. Acral cryotherapy has shown benefit in reducing in in minimizing the incidence and severity ofcidence and severity of CIPN. However, these studies have included limited number of patients (pts) with inconclusive evidence to change US practice guidelines, have been primarily conducted in Asia, and did not include racially diverse patients. Methods: We conducted a single arm non randomized study at Mayo Clinic that included early BC pts who underwent standard of care paclitaxel or docetaxel based chemo. Pts had ECOG performance status 0-2, no sensory peripheral neuropathy at study entry and were able to give signed informed consent. Pts with metastatic BC, Raynaud's and peripheral vascular disease, cryoglobulinemia, cold intolerance, prior exposure to neurotoxic or taxane chemotherapy were excluded. Participating pts wore frozen gloves and socks (−20 to −10°C) on both hands and feet, 15 min before, during and until 15 min post taxane infusion. During chemo, grade (G) of CIPN (sensory) per CTCAE v5 was collected prior to each cycle of chemo, end of and 3 months after chemo. Schedule of events is listed in Table 1. Continuous variables were summarized using mean and standard deviation, and categorical variables were summarized with number and percentage of patients. Numeric variables were compared with t tests (paired and unpaired), and categorical variables were compared with Chi-Squared test for independent data and Mcnemar’s test for dependent data. All statistical tests were two-sided and were performed using R Statistical Software (version 4.1.2; R Foundation for Statistical Computing). Results: A total of 95 patients were included in this study. Median age is 54 years, 66.3% pts were White (W), 23.2% African American (AA), 4.2% Asian (A) and 4.2% Hispanic (H). Median BMI was 27.7. Most pts had stage I/II (75.8%), ER positive (64.9%) and HER2 negative (55.3%) BC and got adjuvant chemo (52.6%). Only 10.6% pts had diabetes, 55.3% used alcohol. Vitamin D3 use seen in 65.6%, B12 in 6.2% and folate, B12 and D3 in 6.2% pts. A total of 41 pts (44.1%) developed neuropathy at some point during chemo, of which 27 pts were W (43%), 10 pts AA (45%), 2 pts H, 1 Asian and 1 other. CIPN was G1 in 37 pts (90%). G2 CIPN was seen in 4 pts, at or after cycle 10 of weekly paclitaxel. Cold intolerance was seen in 24 pts (25%), G1 in 20 and G2 in 4 pts, all seen in cycle 1 with 1 pt withdrawal. Recovery to G0 was seen in 15 W pts at chemo end and 2 additional pts at 3 month after chemo. None of the AA pts, one H and one A pt had CIPN recovery to G0. In 4 AA pts who had G1 CIPN during chemo, G2 CIPN was noted at 3 month follow up. No Statistically significant differences in baseline characteristics and neuropathy results for W vs nonwhites (NW) were seen except Charleson score (p-value 0.023). Conclusion: Acral cryotherapy was found to be effective in reducing the incidence and severity of CIPN from taxane in our study. This is the only study with diverse racial/ethinic pt inclusion and incidence of CIPN was similar in W and NW. However, majority of G2 CIPN pts were AA and recovery to G0 CIPN was not seen in AA pts. Majority (63%) of W pts recovered to G0 at end of follow up. Analysis of objective testing of all pts is underway. Continued research into risk factors for AA pts to develop CIPN and its mitigation are warranted. XX XX Citation Format: Pooja Advani, Jinky Harvey, Ivy Vilches, Alex Hochwald, David Hodge, Amanda Arnold, Morgan Weidner, Dana Haley, Tanmayi Pai, Saranya Chumsri, Rohit Rao, Kostandinos Sideras, Cindy Tofthagen, Alvaro Moreno-Aspitia. Cryotherapy to Prevent Taxane-Induced Sensory Neuropathy of the Hands and Feet [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 PO3-12-10.

Abstract Background The current definition, prognosis, and optimal treatment (tx) for oligometastatic breast cancer (OMBC) are not fully known. With advances in multimodality breast cancer (BC) tx and overall improvement in patient (pt) outcomes, it is important to identify baseline pt factors that confer better prognosis in OMBC and assess the impact of local/regional tx and metastasis (mets)-directed tx on survival outcomes. Methods We reviewed 105 Mayo Clinic pts with OMBC (up to 5 mets) from 2003 to 2021. Pts were excluded from analysis if they were misidentified as having OMBC (n=6), did not have a primary breast mass (n=1), developed de novo BC during tx (n=1), or were lost to follow up (n=2). Categorical variables were summarized as counts. Continuous variables were reported as medians. Kaplan-Meier method was used to estimate survival and the time from diagnosis to next tx at 1, 3, and 5 years. Log-rank test was used to compare survival rates between baseline factors. Univariate Cox proportional hazards models were performed on both baseline and time-dependent factors. All tests were two-sided with p-value < 0.05 considered statistically significant. Results Total pts included were 95. Median age was 49 (range, 26-86), most (93.6%) pts were White, and 46.8% were postmenopausal. Invasive ductal carcinoma (89.5%) was the most common BC type. Median survival was 10.8 years; 1-, 3-, and 5-year survival rates were 98.9%, 87.7%, and 81%, respectively. 58 pts (61.1%) required a change in tx due to disease progression. No significant survival difference was observed in pre- vs. postmenopausal pts (p=0.71) or in groups based on hormone receptor and/or human epidermal growth factor receptor 2 status. 47 pts (49.5%) received local/regional tx; no significant difference in survival (HR 0.57, 95% CI 0.23-1.40; p=0.217) or time to next tx (HR 0.67, 95% CI 0.39-1.15; p=0.144) was seen in this subgroup. Of these pts, 36 (76.6%) received neoadjuvant chemotherapy and/or immunotherapy, 5 of whom (10.6%) also started endocrine tx preoperatively. Overall, 11/47 pts (23.4%) received neoadjuvant endocrine tx. 20 pts received systemic tx without eventual surgery, and 5 pts got palliative radiation (RT). Biopsy-confirmed mets were noted in 76 pts (80%), with bone-only mets in 50%, 30 pts (31.6%) with viscera-only mets and 7 pts (7.4%) with both bone and visceral mets. 18 pts had suspected mets on imaging but did not undergo biopsy. The hazard of death was 6.34 times higher in pts with both bone and visceral mets than those with bone-only mets (p=0.008). Pts with viscera-only mets had higher survival at 2 and 3 years than pts with bone-only or both bone and visceral mets (p=0.093). Pts with 3 mets (7/76, 7.4%) had decreased survival at 1, 2, and 3 years compared to pts with 1-2 (65/76, 85.5%) mets (p=0.6). 67 pts (70.5%) received mets-directed tx; RT alone was the most common modality (52/67, 77.6%), followed by surgery (6/67, 9%), RT plus surgery (5/67, 7.5%), and ablation alone (3/67, 4.5%). There was no significant difference in survival (HR 1.27, 95% CI (0.53, 3.07), p=0.589) or time to next tx (HR 0.95, 95% CI (0.56, 1.63), p=0.856) in pts who received mets-directed tx. Multivariate analysis was not performed because most findings were not statistically significant in univariate analysis. Conclusions We did not find any significant differences in survival based on characteristics like menopausal status or site or number of mets in pts with OMBC. There was a trend toward improved survival in pts with viscera-only mets, but this finding requires validation. Local/regional and mets-directed tx did not improve survival; however, survival at 1, 3, and 5 years was excellent in this OMBC pt population. Our study was limited by low pt numbers and heterogeneity in the pt population. Findings need validation in larger studies. Citation Format: Tanmayi Pai, Raza Zarrar, Zhongwei Peng, Zhuo Li, Lauren Cornell, Kostandinos Sideras, Rohit Rao, Alvaro Moreno-Aspitia, Saranya Chumsri, Sarah McLaughlin, James Jakub, Emmanuel gabriel, Sanjay Bagaria, Laura Vallow, Santo Maimone, Pooja Advani. Clinical Features and Survival Outcomes of Oligometastatic Breast Cancer Patients: The Mayo Clinic Experience [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 PO3-06-04.

Abstract Background: Breast cancer (BC) patients are at significant risk of therapy-related cardiotoxicity, but prediction of which patients will experience cardiotoxicity and the severity of the outcome are lacking. We hypothesized that germline genetic variants are potential risk factors for cancer treatment-related cardiomyopathy (CTRC) and in this study, we focused on rare non-synonymous variants within 57 genes deemed causative of familial and sporadic forms of idiopathic cardiomyopathies. Methods: We developed a clinical database and biorepository for patients receiving any potentially cardiotoxic cancer therapy at Mayo Clinic Florida. Enrollment is ongoing and includes consent to access external records. Patient data is extracted from records at baseline, completion of treatment and then once per year. The clinical database includes the following datasets: demographics, pathology, chemotherapy, radiation, echocardiography, cardiac MRI, PET/CT scan, blood pressure, BMI, labs, treatment complications. Treatment complications includes pre-existing conditions (smoking, alcohol and drug use history, hypertension, diabetes, coronary artery disease, hyperlipidemia, prior stroke or myocardial infarction, peripheral vascular disease, renal failure); cardiac medications at baseline; cardiac side-effects; time to cardiotoxicity; cardiotoxicity interventions and outcomes. Exome sequencing was performed by the Mayo Clinic NGS core on the first 86 patients in the registry, average of ~120x read depth following Illumina’s standard protocol for the NovaSeq 6000 and S4 flow cell. Genomic variants were extracted for 57 genes known to be causative of dilated, hypertrophic and arrhythmogenic right ventricular cardiomyopathies and channelopathies. Putative risk variants in known cardiomyopathy genes were defined as non-synonymous variants with a frequency of < 0.0004 in the GnomAD database. We compared the number of patients with putative risk variants in those groups with and without CTRC. Results: 84/86 patients had BC diagnosis. Key characteristics are described in the table below. 60/86 (70%) patients had at least one putative risk variant in one of 31 genes (there were no risk variants identified in 27/57 genes). The average number of putative risk variants per patient within the CTRC group was higher than that observed in patients without CTRC (2.06 vs 1.62). Post-hoc analysis suggested this difference is largely from patients with >2 risk variants in the group who experienced CTRC (N=7/17, 41%) compared to those who did not (N=14/69, 20%), p=0.023. Conclusions: Rare missense variants in the causative genes of idiopathic cardiomyopathies are potential risk factors for CTRC and risk may be increased in patients with a higher burden of variants. Analysis of the genetic data from patients that continue to be accrued in this study, including effects of additional clinical risk factors will be undertaken to improve prediction of cardiotoxicity. Table 1 Distribution of putative cardiomyopathy genetic variants in 86 cancer patients with and without treatment-related cardiomyopathy, separated by treatment regimen Citation Format: Nadine Norton, Thien Nguyen, Joseph Reddy, Jinky Harvey, Morgan Weidner, Amanda Arnold, Lily Evans, Laura Vallow, Pooja Advani. Increased burden of genetic variants in idiopathic cardiomyopathy genes is associated with cancer therapy-related cardiomyopathy [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 PO2-12-08.