High-risk Triple-negative Breast Cancer Research Articles

Abstract PO4-25-03: Comprehensive immune profiling reveals factors associated with neoadjuvant chemotherapy response in triple negative breast cancer

Abstract Background: KEYNOTE-522 has resulted in FDA approval of the immune checkpoint blocker pembrolizumab with neoadjuvant chemotherapy for patients with high-risk triple negative breast cancer (TNBC), given the remarkable improvement in pCR rate to 65% along with improvement in event free survival, while with chemotherapy alone, the pCR rate is 40-50%. Unfortunately, use of pembrolizumab is associated with several immune related adverse events (irAE), some of which can be life-threatening and debilitating, including cardiomyositis, encephalitis, and adrenal insufficiency, among others. Hence, there is an unmet need to identify biomarkers in the tumor microenvironment which could predict patients who may attain pCR with chemotherapy alone and be spared the side effects from the added PD-1 inhibition. Methods: Comprehensive immune profiling, including PD-L1 IHC and the expression of 395 immune genes by RNA-seq, was performed on 1:2 matched FFPE tumor samples from 23 stage 1-3 TNBC patients (2 stage 1, 6 stage 2, 15 stage 3). All patients were female with an average age of 48 years (range: 25-79 years). 14 patients were treated with neoadjuvant chemotherapy alone (NAC) and 9 were treated with neoadjuvant chemotherapy combined with the checkpoint inhibitor pembrolizumab (NAC+I). mRNA expression signatures of tumor inflammation (TIGS, weak/moderate/strong), cell proliferation (CP, poor/moderate/high), and cancer testis antigen expression burden (CTAB) were determined by RNA-sequencing. Statistical comparisons of quantitative biomarkers between groups were calculated using the Wilcoxon Rank-Sum test, overrepresentation analysis of categorical variables between groups was calculated by proportions test, and survival differences were quantified by Cox proportional hazards analysis. Pathological responses were documented as pathological complete response (pCR) vs. non-pCR. Results: Across the entire cohort, patients with a BMI < 30 had significantly higher PD-L1 expression (assessed by RNA) than those with a BMI ³ 30 [p=0.047]. While not a statistically significant association, the NAC+I group tended to have a higher pCR rate compared to the NAC group [44.4% vs. 28.6%, p=0.66]. Across the entire cohort, tumors with high CTA expression, designated as CTAB high, had a higher pCR rate than CTAB low tumors [54.5% vs 16.7%, p=0.089]. No significant difference in pCR rate between TIGS or CP groups was detected for the NAC group, but in the NAC+I group, highly proliferative tumors had a lower pCR rate than moderately proliferative tumors [0% vs. 80%, p=0.048]. The pCR and non-pCR groups for each treatment type also exhibited distinct gene expression profiles. Among the NAC group, underexpression of FOXP3 and overexpression of MAPK14 and CD44 were associated with pCR [p≤0.031], while underexpression of IFNB1, MAPK14, and CD44 was associated with non-pCR [p≤0.029]. Among the NAC+I group, overexpression of CXCR4, TNFR and CCL20 was associated with non-pCR [p≤0.046]. Interestingly, SDHA was significantly overexpressed in the non-pCR subset of patients in the NAC group and significantly underexpressed in the non-pCR subset of patients in the NAC+I group [p≤0.031]. Conclusions: The development of biomarkers of treatment response is essential to the integration of immunotherapy with chemotherapy as a combined cancer treatment. Our study profiled the immune context of both NAC and NAC+I and identified several key microenvironmental differences underlying divergent treatment response in both groups. A comprehensive understanding of these factors could potentially predict pCR to chemotherapy alone, enabling the avoidance of the unnecessary treatment of these tumors with immunotherapy. Citation Format: Robert Seager, Heidi Ko, Sarabjot Pabla, Maria-Fernanda Senosain, Pawel Kalinski, Erik Van Roey, Shuang Gao, Kyle Strickland, Rebecca Previs, Mary Nesline, Stephanie Hastings, Shengle Zhang, Jeffrey Conroy, Taylor Jensen, Marcia Eisenberg, Brian Caveney, Eric Severson, Shakti Ramkissoon, Shipra Gandhi. Comprehensive immune profiling reveals factors associated with neoadjuvant chemotherapy response in 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 PO4-25-03.

Abstract PO3-03-11: Receptor discordance after neoadjuvant chemotherapy with pembrolizumab in early-stage triple-negative breast cancer

Abstract Background: Discordance in hormone receptor (HR) and/or HER2 status between matched primary tumors and residual specimens following neoadjuvant therapy is a known phenomenon. In the neoadjuvant setting, systemic treatment is primarily informed by the HR and HER2 status from the diagnostic biopsy. Current guidelines recommend additional adjuvant capecitabine and/or pembrolizumab and/or olaparib for patients with triple-negative breast cancer (TNBC) after neoadjuvant systemic therapy if residual disease is present at the time of surgery. Discordance in biomarker status between the initial diagnosis and residual cancer may impact postoperative systemic therapy recommendations. This study aims to investigate the discordance rate in HR and HER2 status after neoadjuvant chemotherapy (NAC) plus pembrolizumab in early-stage TNBC. Furthermore, given the emerging data in support of novel antibody-drug conjugates (ADCs) for HER2-low breast cancer, the prevalence of HER2-low disease following standard-of-care neoadjuvant therapy may have critical clinical importance. Methods: We performed a single-institution, retrospective study of early-stage TNBC patients diagnosed between February 1st, 2020 and December 1st, 2022 who were treated with neoadjuvant chemotherapy and pembrolizumab. Patients who had not undergone definitive surgery were excluded. Demographic information, clinical and pathologic characteristics, and treatment data were collected from an institutional database. Pathologic complete response (pCR) was defined as ypT0/Tis and ypN0. HR and HER2 status before and after neoadjuvant therapy were collected. This study was approved by an Institutional Review Board. Results: Among the 94 patients included the median age was 55 years (IQR 47.0-61.8). The majority of patients had invasive ductal carcinomas (90.4%), were clinical T2 stage (68.1%), and node negative (55.3%). On the core tumor biopsy, estrogen receptor (ER) was < 1% in 90 (95.7%) patients and 1-10% in 4 (4.3%) of patients. Progesterone receptor (PR) was < 1% in 91 (96.8%) of patients and 1-10% in 3 (3.2%) of patients. HER2 was 0 by IHC in 49 (52.1%) patients, 1+ in 30 (31.9%) patients, 2+ in 11 (11.7%) patients, and not performed in 4 (4.3%) patients. A pCR (ypT0/Tis ypN0) was achieved in 60 (63.8%) of the 94 patients. In the 34 patients with residual disease, 29 patients had ER status evaluated at the time of surgery. Of these patients, 4 had tumors with ER < 1% at baseline but >5% at surgery. 28 patients with residual disease had PR evaluated at the time of surgery. Of these patients, all had tumors with PR < 1% at the time of surgery. 28 patients had residual tumors with HER2 status evaluated at the time of surgery (table). Of these patients, 18 (64.3%) tumor specimens were HER2-ultra-low, 9 (32.1%) were HER2-low-positive, and 1 (3.6%) was HER2-positive. Conclusion: Receptor discordance from the time of initial biopsy to residual disease can occur in patients with early-stage TNBC treated with NAC with pembro. As additional systemic therapy is indicated in patients who do not achieve pCR, accurate tumor marker status is critical. This study highlights the potential impact of reassessment of HR and HER2 status on the surgical tumor specimen. Clinical trials that tailor adjuvant therapy recommendations based on residual biomarker analyses may further improve outcomes for women with high risk TNBC. Table. Discordance in HER2 Status Between Primary Tumor and Residual Specimen Citation Format: Alexis LeVee, Megan Wong, Sarah Flores, Nora Ruel, Heather McArthur, James Waisman, Joanne Mortimer. Receptor discordance after neoadjuvant chemotherapy with pembrolizumab in early-stage 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 PO3-03-11.

Abstract PO1-28-07: Neoadjuvant docetaxel plus cisplatin versus docetaxel plus doxorubicin and cyclophosphamide in early-stage triple-negative breast cancer (HNBC-001): results from a multicenter, randomized controlled, open-label phase II trial

Abstract Background: Adding platinum to anthracycline- and taxane-based neoadjuvant chemotherapy has improved pathological complete response (pCR) in patients with triple-negative breast cancer (TNBC). However, the efficacy of combining docetaxel and platinum without anthracycline remains controversial. Methods: The HNBC-001 trial was a randomized, phase 2 controlled, and open-label investigation carried out in China at 6 hospitals. The participants who were aged 18–70 years, were histologically confirmed for TNBC clinical stage II–III, suitable for potentially curative surgery, and had an Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0 or 1 were selected for this trial. Participants were randomly categorized into two equal groups; those who received docetaxel plus cisplatin (75 mg/m2, respectively) and those who received docetaxel plus doxorubicin and cyclophosphamide (docetaxel 75 mg/m2, doxorubicin 50 mg/m2, and cyclophosphamide 500 mg/m2). These regimens were given every 3 weeks for 6 cycles. Randomization was stratified by tumor size and nodal status. The primary endpoint was the number of individuals achieving a pCR (ypT0/is ypN0). The trial was registered with chictr.org (number ChiCTR-1800019501). Results: Between November 28, 2018, and June 11, 2022, 212 patients were selected (n=106/treatment). The number of individuals who achieved pCR after docetaxel plus cisplatin treatment was 51.9%, and that of those who attained pCR after docetaxel plus doxorubicin and cyclophosphamide was 35.8% (P=0.019). After 21 months of median follow-up [interquartile range (IQR), 13 to 33], 11 of 106 patients (10.4%) in the docetaxel plus cisplatin group and 14 of 106 patients (13.2%) in the docetaxel plus doxorubicin and cyclophosphamide group had event-free survival (EFS) events [95% confidence interval (CI) =0.360 to 1.783, hazard ratio (HR) =0.801, P=0.585]. The incidence of grade 3 or 4 events was similar in both groups [57 (54%) vs. 51 (48%)]. However, no treatment-associated deaths were identified. Conclusions: In stage II to III TNBC, the docetaxel plus cisplatin regimen achieved higher pCR rates than docetaxel plus doxorubicin and cyclophosphamide, with a manageable toxicity profile. Consistent with the literature, the docetaxel plus cisplatin regimen demonstrated a favorable risk-to-benefit profile and could serve as an optimal neoadjuvant chemotherapy option for patients with high-risk TNBC. table 1: Patient characteristics figure 1: Study endpoints Error bars denote 95% CIs based on normal approximation. p values were calculated from the Chi-square test. (A) Frequency of patients who achieved a pathological complete response per treatment group (primary endpoint). (B) Frequency of patients who achieved a clinical breast tumour response per treatment group, assessed by serial MRI scans after completion of neoadjuvant treatment. (C) Frequency of patients who achieved a minimal residual disease (residual cancer burden class 0 or 1). (D) Frequency of patients who received breast-conservation surgery. table 2: Treatment-emergent adverse events Citation Format: Dechuang Jiao, Jianghua Qiao, Chengzheng Wang, Juntao Li, Xianfu Sun, Zhenduo Lu, Chongjian Zhang, Lianfang Li, Min Yan, Yueqing Feng, Yong Zhou, Miao Deng, Xinlan Liu, Mingde Ma, Haiquan Jia, Qingxin Xia, Xiuchun Chen, Zhenzhen Liu. Neoadjuvant docetaxel plus cisplatin versus docetaxel plus doxorubicin and cyclophosphamide in early-stage triple-negative breast cancer (HNBC-001): results from a multicenter, randomized controlled, open-label phase II 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 PO1-28-07.

Abstract PS16-06: Tumor-infiltrating lymphocytes and pathologic response to neoadjuvant chemotherapy with the addition of platinum and pembrolizumab in TNBC: A single-center real-world study

Abstract Background Previous studies have presented compelling evidence suggesting that the inclusion of platinum agents alongside anthracyclines and taxanes could potentially enhance treatment outcomes in high-risk triple-negative breast cancer (TNBC). Moreover, pembrolizumab has been integrated into clinical practice as a part of standard-of-care for non-metastatic TNBC with high risk. In light of these findings, we undertook a real-world study to investigate the impact of incorporating platinum agents and pembrolizumab on achieving pathologic complete response (pCR) in TNBC patients undergoing neoadjuvant chemotherapy (NAC). Furthermore, we specifically examined the influence of tumor-infiltrating lymphocytes (TILs) on the treatment outcomes. Patients and Methods In this real-world study conducted at Gangnam Severance Hospital, Seoul, Republic of Korea, we analyzed a cohort of 398 patients with TNBC who underwent surgery following NAC between March 2007 and November 2022. Among them, 247 patients received an anthracycline-taxanes (A-T), 120 received a carboplatin regimen including A-T, and 31 received a pembrolizumab regimen including A-T-carboplatin as part of their neoadjuvant chemotherapy treatment. TIL was evaluated in biopsied samples prior to NAC according to the guideline of TIL international working group. The high TIL was defined with a cutoff of 50%. Results Among the 398 patients analyzed, 87 (21.9%) had high TIL tumors. The pCR rates were 32% in the anthracycline-taxane (A-T) regimen group, 57% in the A-T-carboplatin regimen group, and 68% in the pembrolizumab with A-T-carboplatin regimen group. Within the high TIL group, the pCR rate did not increase with the addition of carboplatin (51.8% in the A-T group and 41.7% in the A-T-carboplatin group), but reached 85.7% with the addition of pembrolizumab and carboplatin. Among the low TIL group, the pCR rate increased from 26.7% to 61.1% with the addition of carboplatin, but there was no difference in the pCR rate between the carboplatin and pembrolizumab groups (61.1% and 60.9%, respectively). In clinically node-positive patients, the pCR rate significantly increased with pembrolizumab in the high TIL group (40.9% versus 100%, p=0.035). However, in low TIL patients, the addition of carboplatin alone significantly increased the pCR rate to 62.3%, whereas the addition of pembrolizumab did not show the same effect. Conclusions Our real-world data consistently demonstrates an increased pCR rate with the addition of carboplatin and pembrolizumab. Among patients with high TIL, the addition of carboplatin did not result in an elevated pCR rate. However, the addition of pembrolizumab tended to maximize the pCR rate, surpassing 80%. On the other hand, among patients with low TIL, the addition of carboplatin significantly increased the pCR rate, while the addition of pembrolizumab did not have the same effect. Efforts should be made to improve the response to pembrolizumab-containing regimens for patients with low baseline TIL levels. Citation Format: Min Ji Kim, Yoonwon Kook, Seung Ho Baek, Junghyun Kim, Sohyun Moon, Seung Eun Lee, Jee Hung Kim, Soong June Bae, Sung Gwe Ahn, Joon Jeong. Tumor-infiltrating lymphocytes and pathologic response to neoadjuvant chemotherapy with the addition of platinum and pembrolizumab in TNBC: A single-center real-world study [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 PS16-06.

Abstract PO5-17-01: Pre-treatment tumor infiltrating lymphocytes are associated with higher likelihood of pathologic complete response among black women with TNBC receiving neoadjuvant chemoimmunotherapy

Abstract Background: High risk, early-stage triple negative breast cancer (TNBC) is a heterogenous disease that is associated with early recurrence and high mortality, particularly among black women as compared to their white counterparts. Pathologic complete response (pCR) to neoadjuvant chemotherapy (NACT) is a strong-predictor of long-term disease-free survival in TNBC, and the KEYNOTE-522 trial demonstrated that the addition of immunotherapy (pembrolizumab) to NACT resulted in a higher likelihood of pathologic complete response (pCR) in high-risk early-stage TNBC. Following these findings, the standard of care has been to administer the K522 regimen (K522R) in the neoadjuvant setting for patients with high risk early-stage TNBC. However, our understanding of the clinical and tumor characteristics to prognosticate response to K522 are lacking, and additional real-world data is needed to better understand if these variables differ among race. Methods: We evaluated 76 patients who were treated with the K522R at our institution. There were slides available from 29 patients’ pre-treatment biopsies for pathology review. In the available slides, tumor infiltrating lymphocytes (TIL) were evaluated as the percentage of lymphocytes in the stroma within the tumor area. For the remaining cases that did not have available slides, these variables were retrieved from pathology reports and patients’ charts. Patient characteristics including age, race and body mass index (BMI) were acquired via retrospective chart review. These clinicopathologic variables were correlated with pCR, which was defined by the absence of invasive carcinoma in the breast and axillary lymph nodes at the time of surgery. Binary logistic regression analysis was performed to correlate the above variables with pCR versus residual disease (RD). Results: Seventy-six pre-treatment biopsy specimens treated with the K522R were evaluated. The patient population spanned a broad spectrum of age, body habitus, and race, with mean age 55, mean BMI 28.3, and predominantly black (over 60 percent) population. At the time of analysis, 64 of the 76 patients had completed the K522R and subsequently undergone surgery at our institution. Of the 64 patients who had undergone definitive surgery, 31 (48.4%) achieved pCR. In univariate analysis, pre-treatment TIL was significantly associated with attainment of pCR, with TIL of 28.5% (± 19.1) in patients who achieved pCR versus 9.73% (± 9.40) in those who had RD (95% CI 1.03-1.21, p=0.014*). When TIL was further stratified by race, mean percentage of TIL was significantly higher among black women who achieved pCR (27.5% ± 4.7) compared to black women with RD (12.2% ± 3.05) (95% CI 0.021 – 0.197, p=0.016*). Additionally, mean percentage of TIL was higher overall among black women when compared to the white patients in our cohort, though this finding was not statistically significant (p=0.252). Conclusion: Our real-world data demonstrates high levels of pre-treatment TIL are significantly associated with achievement of pCR in patients with TNBC treated with the K522 regimen. When TIL was further stratified by race, black patients were found to have higher TIL than white patients. Within the black population, a statistically significant difference in TIL percentage was found in those achieving pCR compared to those with RD. It is well understood that black women often have poorer breast cancer outcomes than white women, and our finding of higher TIL percentage among this population, along with the significant association between TIL and attainment of pCR with chemoimmunotherapy, could have important implications for optimization of therapy. Further exploration of this phenomenon in larger, diverse breast cancer populations is warranted. Citation Format: Sarah Wood, Ji-Hoon Lee, Yuan Gao, Xiaoxian Li, Jane Meisel. Pre-treatment tumor infiltrating lymphocytes are associated with higher likelihood of pathologic complete response among black women with TNBC receiving neoadjuvant chemoimmunotherapy [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 PO5-17-01.

Abstract PO2-03-07: Immune Landscape in PD-L1-positive and TROP2-positive Triple-Negative Breast Cancer

Abstract Background: Triple-negative breast cancer (TNBC) tends to be more aggressive, and more likely to recur than other subtypes of breast cancer, and patients with metastatic TNBC have a poor prognosis. The recent approvals and data of pembrolizumab (anti-PD-1 inhibitor) in combination with chemotherapy in advanced-metastatic and early high-risk TNBC, and sacituzumab govitecan (an ADC that targets the tumor cell surface antigen TROP2 coupled with the irinotecan metabolite SN-38) in metastatic TNBC, has shed light on some of the immune and cancer signaling associated with TNBC. Although exciting progress has been made in the treatment of TNBC, there are still important gaps to fill to understand the biology of TNBC and identify additional therapies. Materials and Methods: We identified a total of 1500 patients whose tumors were negative for the expression of ER and HER2 receptors by gene array. PD-L1 and TROP2 expression data were available for 802 early TNBC patients, of whom 657 were treated with adjuvant chemotherapy. A comprehensive identification and analysis of immune-related genes (n= 1169) was conducted. Mann-Whitney test comparing the gene expression for all immune related-genes was evaluated in patients expressing PD-L1 and TROP2 at low and high expression levels. Immune gene modules resembling key immune gene signaling were analyzed in all subgroups identified. Fold changes and Mann-Whitney P values were calculated in each subgroup. Results: Patients were stratified based on high and low expression levels of PD-L1 and TROP-2 mRNA. PD-L1 highly expressing (PD-L1+) tumors showed a marked difference in immune-related genes as compared to PD-L1 low-level tumors (PD-L1-) with PD-L1+ tumors demonstrating a significantly higher proportion of correlated immune genes (CXCL9/10/11, IFN-γ, CCL5 and STAT1). TROP2 highly and low expressing tumors (TROP2+ and TROP2-, respectively) showed a relatively limited difference in terms of immune-related gene expression with key immune-related genes having statistical differential expression in the two subgroups. TROP2+ tumors showed a high presence of several Mucin family gene members (MUC1, -5AC, -4). In addition, CLDN 4, VTCN1, and MET were among the key immune genes significantly expressed in TROP2+ tumors (P = 5.73E-20; P = 6.2E-13, P = 2.1E-11). Overall, PD-L1+ tumors and TROP2+ tumors showed an immune suppressive genomic landscape but were potentially regulated by different signaling. Of note, tumors with very high expression of PD-L1 showed an inverse correlation with VTCN1 gene expression. Conclusions: This preliminary analysis confirmed that only a limited number of early TNBC highly expressed PD-L1 and that a different immune suppressive landscape for PD-L1± and TROP2± tumors exists. In addition, our data suggest that early TNBC cases lacking PD-L1 might escape immune surveillance by virtue of the upregulation of key alternate signaling. Ongoing efforts investigating the expression of such markers on stroma/epithelial tumor components will help to clarify their biological, clinical, and potential therapeutic role in TNBC. Citation Format: Balazs Gyorffy, Libero Santarpia. Immune Landscape in PD-L1-positive and TROP2-positive 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 PO2-03-07.

Abstract 7664: Early detection of racial disparity and treatment resistance in triple negative breast cancer

Abstract Introduction: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that disproportionately affects BRCA1 mutation carriers and young Black/African American (AA) women. Black/AA patients have the highest mortality and the shortest survival of any racial/ethnic group in the US. With the approval of pembrolizumab, the addition of immune checkpoint blockade (ICB) to neoadjuvant chemotherapy (NACT) has become the standard of care (SOC) for high-risk early-stage TNBC. The pathologic complete response (pCR) is a reliable prognostic marker that correlates with tumor remission and good outcome, whereas pathologic incomplete response (pIR) with high residual cancer burden (RCB) is often associated with early relapse, treatment resistance, and poor survival. Many similarly-treated patients with identical TNM and RCB classifications still experience racial disparity, different relapse rates, and disparate survival. Current methods fall short in predicting tumor recurrence/chemo-resistance/patient survival with high accuracy in the clinic. Methods: We detected a major racial disparity in our large regional cohorts of TNBC patients (> 1,000 patients), of which 48% patients are Black/AA and 48% patients are white patients, at the Sentara Cancer Network and VCU Massey Comprehensive Cancer Center, that have historically provided excellent healthcare and quality cancer care to the social-economically-disadvantaged, medically underserved, and underinsured racial/ethnic minorities in low income communities in Virginia. Despite Sentara/VCU’s best efforts, Black/AA breast cancer patients still suffer 70-100% higher MBC mortality, and the worst survival compared to their white counterparts, based on our clinical studies and the SEER/CDC databases. Result: We showed that persistent EGFR/RAS/SIAH pathway activation is a major driving force of TNBC malignancy. The most downstream and evolutionarily conserved signaling gatekeeper, SIAH, is an RING domain E3 ligase that is a high-resolution prognostic biomarker for patient risk stratification and racial disparity prediction in TNBC. High SIAH expression in residual tumors reflects ineffective NACT/IO therapy and persistent EGFR/K-RAS/SIAH pathway activation (ON) that drives tumor relapse, resistance, and reduced survival. Low SIAH expression in residual tumors reflects effective NACT/IO therapy and EGFR/K-RAS/SIAH pathway inactivation (OFF) that predicts tumor remission, good outcome, and prolonged survival. We found that SIAH expression is 2.0-fold higher in Black/AA patients’ residual tumors than in the white patients’ residual tumors, mirroring a 1.8-2.0-fold higher death rates in the Black/AA patients than the white patients. Conclusion: In this study, we demonstrate the prognostic power of SIAH for patient risk stratification, therapy quantification, and relationship to cancer racial disparity in TNBC. Citation Format: Amy H. Tang, Richard A. Hoefer, Mary L. Guye, Billur Samli, Janet S. Winston, Jennifer Koblinski, Valentina Robila, Michael O. Idowu, Rick J. Jansen, Harry D. Bear. Early detection of racial disparity and treatment resistance in triple negative breast cancer [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 7664.

Ferroptosis Inducers Upregulate PD-L1 in Recurrent Triple-Negative Breast Cancer.

(1) Background: Triple-negative breast cancer (TNBC) is a distinct subgroup of breast cancer presenting a high level of recurrence, and neo-adjuvant chemotherapy is beneficial in its therapy management. Anti-PD-L1 immunotherapy improves the effect of neo-adjuvant therapy in TNBC. (2) Methods: Immune-modulation and ferroptosis-related R-packages were developed for integrative omics analyses under ferroptosis-inducer treatments: TNBC cells stimulated with ferroptosis inducers (GSE173905, GSE154425), single cell data (GSE191246) and mass spectrometry on breast cancer stem cells. Clinical association analyses were carried out with breast tumors (TCGA and METABRIC cohorts). Protein-level validation was investigated through protein atlas proteome experiments. (3) Results: Erastin/RSL3 ferroptosis inducers upregulate CD274 in TNBC cells (MDA-MB-231 and HCC38). In breast cancer, CD274 expression is associated with overall survival. Breast tumors presenting high expression of CD274 upregulated some ferroptosis drivers associated with prognosis: IDO1, IFNG and TNFAIP3. At the protein level, the induction of Cd274 and Tnfaip3 was confirmed in breast cancer stem cells under salinomycin treatment. In a 4T1 tumor treated with cyclophosphamide, the single cell expression of Cd274 was found to increase both in myeloid- and lymphoid-infiltrated cells, independently of its receptor Pdcd1. The CD274 ferroptosis-driver score computed on a breast tumor transcriptome stratified patients on their prognosis: low score was observed in the basal subgroup, with a higher level of recurrent risk scores (oncotypeDx, ggi and gene70 scores). In the METABRIC cohort, CD274, IDO1, IFNG and TNFAIP3 were found to be overexpressed in the TNBC subgroup. The CD274 ferroptosis-driver score was found to be associated with overall survival, independently of TNM classification and age diagnosis. The tumor expression of CD274, TNFAIP3, IFNG and IDO1, in a biopsy of breast ductal carcinoma, was confirmed at the protein level (4) Conclusions: Ferroptosis inducers upregulate PD-L1 in TNBC cells, known to be an effective target of immunotherapy in high-risk early TNBC patients who received neo-adjuvant therapy. Basal and TNBC tumors highly expressed CD274 and ferroptosis drivers: IFNG, TNFAIP3 and IDO1. The CD274 ferroptosis-driver score is associated with prognosis and to the risk of recurrence in breast cancer. A potential synergy of ferroptosis inducers with anti-PD-L1 immunotherapy is suggested for recurrent TNBC.

Leveraging cryoablation and checkpoint inhibitors for high-risk triple negative breast cancer.

Breast cancer is the second most common cancer among women in the United States in which the standard of care treatment is surgery with adjunctive therapy. Cryoablation, which destroys the tumor using extremely cold temperatures while preserving the potential tumor antigens, is a promising alternative to surgical resection. It is less invasive, cosmetically appeasing, cost-effective, and capable of contributing to the abscopal effect - the immune response targeting potential distant metastasis. However, to maximize the immunologic benefit of cryoablation in biologically high-risk breast cancers, combination with therapies that enhance immune activation, such as immune checkpoint inhibitors (ICIs) may be necessary. This mini review describes the fundamentals of cryoablation and treatment with ICIs, as well as discuss the caveats in both strategies and current clinical trials aimed to improve this approach to benefit patients.

LBA19 Event-free survival (EFS) analysis of neoadjuvant taxane/carboplatin with or without atezolizumab followed by an adjuvant anthracycline regimen in high-risk triple negative breast cancer (TNBC): NeoTRIP Michelangelo randomized study

LBA19 Event-free survival (EFS) analysis of neoadjuvant taxane/carboplatin with or without atezolizumab followed by an adjuvant anthracycline regimen in high-risk triple negative breast cancer (TNBC): NeoTRIP Michelangelo randomized study

Disease outcomes by race in patients with high-risk triple negative breast cancer with residual disease after neoadjuvant chemotherapy: A post-hoc analysis of the EA1131 randomized clinical trial.

586 Background: Black women with breast cancer have the highest breast cancer mortality (BCM) rates of any racial and ethnic group. The higher burden of triple negative breast cancer (TNBC) in Black women contributes to disparities in BCM, but the extent to which disparate outcomes exist in patients with similar tumor biology is uncertain. The objective of this study was to examine racial differences in disease outcomes and BCM between Black and White patients in a clinical trial population of high-risk TNBC with residual disease after neoadjuvant chemotherapy (NAC). Methods: From 2015-2021, the ECOG-ACRIN EA1131 clinical trial randomized 415 clinical stage II-III TNBC patients with residual disease after NAC to either adjuvant capecitabine or platinum. For this analysis, 366 patients with known self-reported Black or White race and follow-up data were included. The aim of this unplanned exploratory analysis was to examine locoregional recurrence (LRR), distant recurrence (DR), and BCM by race using Kaplan-Meier curves for unadjusted estimates and Cox modeling for adjusted analyses. Results: Racial distribution of the analysis population included 66 (18.0%) Black and 300 (82.0%) White patients. 239 (65.3%) patients presented with clinical stage II and 127 (34.7%) with stage III disease. All patients had residual pathological disease after NAC: 86 (23.5%) stage I, 176 (48.1%) stage II, and 102 (27.9%) stage III (n=2 unknown). Median age was 49 years in Black and 54 years in White patients, p=0.003. Disease presentation, response to chemotherapy, and treatment arm were similar by race. Median follow up was 20 months. 2-year estimated LRR occurred in 31.6% of Black and 18.6% of White patients although this was not statistically significant (p=0.387), and 2-year estimated DR and BCM were similar by race. Estimated 2-year outcomes are outlined. Models adjusted for race, age, stage, grade, treatment arm, and locoregional therapy did not identify race as an independent predictor of LRR, DR, or BCM. Higher pathologic stage was the only consistent independent predictor of recurrent disease or BCM (stage III with HR 6.14 for LRR; HR 5.16 for DR; HR 6.84 for BCM; all p<0.001). Conclusions: In this population of high-risk patients with residual TNBC after NAC with similar tumor biology treated on a clinical trial, there was a trend towards increased LRR in Black patients and similar DR and BCM between Black and White patients at 2 years of follow-up. This suggests that differences in BCM in other breast cancer populations may be at least partially driven by differences in tumor biology. Clinical trial information: NCT02445391 . [Table: see text]

Factors associated with response to neoadjuvant chemotherapy and immune checkpoint inhibition in triple-negative breast cancer.

e12593 Background: Immune checkpoint inhibition with pembrolizumab plus neoadjuvant chemotherapy is now the standard-of-care in patients with high-risk triple-negative breast cancer (TNBC) based on the KEYNOTE-522 trial. The trial demonstrated that the addition of pembrolizumab improves pCR, but it is currently unclear which patients benefit most from the addition of immunotherapy (IO). We sought to identify which demographic and clinical characteristics were associated with response to neoadjuvant pembrolizumab plus chemotherapy. Methods: We performed a single institution, retrospective study of early-stage TNBC patients treated with neoadjuvant chemotherapy and pembrolizumab between March 1st, 2020 and December 1st, 2022. We excluded patients who had not undergone definitive surgery. We collected demographic information, clinical and pathologic characteristics, and treatment data. Pathologic complete response (pCR) was defined by ypT0/Tis and ypN0. Multivariate analysis was performed using logistic regression to identify factors associated with pCR. This study was approved by the City of Hope Institutional Review Board. Results: 67 patients were analyzed with a median age of 56 years and median BMI of 29. Self-reported racial groups included 25 Hispanic patients (37%), 23 non-Hispanic White (34%), 9 Asian (13%), 6 Black (9%), and 4 other/unknown (6%). 6 (9%) patients were BRCA1+ and 1 (1.5%) patient was BRCA2+. The majority of patients had invasive ductal carcinomas (91%), were clinical T2 stage (65.7%), and node negative (52.2%). The median number of cycles of neoadjuvant IO was 7 (IQR 4-8) and median months from start of IO to surgery was 6 (IQR 4.6-6.7). 42 (62.7%) patients had a pCR. Multivariate results showed that patients under 50 years at time of diagnosis (vs. age > 50 years), those with grade 3 (vs. 2), and those receiving 7 or more cycles of pembrolizumab (vs. < 7) had improved rates of pCR (ORs 5.7, 8.1, and 3.4, respectively, p < 0.05). BMI, race, BRCA1/2 status, histopathology, clinical T and N stage, and timing of start and end of IO to surgery were not significantly associated with pCR. Conclusions: Younger TNBC patients with high tumor grade were more likely to respond to treatment with neoadjuvant pembrolizumab and chemotherapy. More cycles of treatment with pembrolizumab was also associated with response. Further research to identify which patients with TNBC benefit from the addition of pembrolizumab to chemotherapy is necessary to determine whether its additional toxicity and cost are warranted.

Abstract 6051: Dissecting unique metabolic vulnerabilities in triple-negative breast cancer metastasis

Abstract Introduction. Triple-negative breast cancer (TNBC) exhibits the worst outcome due to an aggressive clinical course, high rates of metastasis, and therapeutic resistance. Lack of effective FDA approved anti-metastatic targeted therapies has generated an unmet medical need for developing effective novel treatments. Targeting metastatic seeding and colonization remains a therapeutic challenge. Only recently, attention has been drawn to the idea that cancer cells selectively and dynamically adapt their metabolism along the changing microenvironments of the metastatic cascade. However, the precise nature of the metabolic reprograming in vivo is poorly understood and constitutes a major barrier in formulating a rationally designed therapeutic approach. Using a genetic lineage tracing approach, we identified a discrete subpopulation of highly metastatic SOX2/OCT4+ cells within primary tumors that exhibit enhanced invasion and metastasis, increased self-renewal, higher chromosomal instability, and marked resistance to chemotherapy. We posited that this lineage tracing system may allow assessment of precise metabolic alterations as a function of tumor progression directly in vivo. Methods and data. Transcriptomic analysis of sorted cellular fractions from progressing primary TNBC tumor identified metabolic heterogeneities between metastatic SOX2/OCT4+ and the SOX2/OCT4- counterparts. SOX2/OCT4+ metastatic cells exhibited elevated levels of mitochondrial respiration (OXPHOS) and fatty acid (FA) metabolism; a finding supported by proteomic analysis. Using a combination of CRISPR knockout of key pathway genes, seahorse metabolic flux analysis, metabolomics, and stable isotope tracing, we provide evidence for increased dependence of the metastatic SOX2/OCT4+ population on these unique metabolic adaptions. Importantly, we have identified upstream regulators of these pathways and demonstrate impact of both genetic and pharmacological inhibition of the metabolic regulatory networks on metastasis in vivo. Conclusion. By identifying metabolic adaptations unique to the metastatic compartment of the primary tumor, we provide evidence for using clinical grade pharmacological inhibitors including metformin, tetrathiomolybdate and FA pathway inhibitors like TVB-2640 and BMS-303141, as an anti-metastatic approach in TNBC. This knowledge of metabolic remodeling could therefore be employed as a next-generation therapeutic approach for high-risk TNBC patients. Citation Format: Divya Ramchandani, Liron Yoffe, Arshdeep Singh, Linda Vahdat, Vivek Mittal. Dissecting unique metabolic vulnerabilities in triple-negative breast cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6051.

Abstract 3311: Tumor cell total mRNA level predicts disease progression across multi-ethnic patient cohorts with triple-negative breast cancer

Abstract Tumor heterogeneity presents a major challenge in the clinical management of breast cancers by impacting patient’s prognosis, therapeutic response, and clinical outcomes. Triple-negative breast cancer (TNBC) carries the worst prognosis among all the breast cancer intrinsic subtypes and has limited treatment options. Currently, TNBC subtypes are mainly refined into four categories: basal-like (BL1 and BL2), luminal androgen receptor (LAR) and mesenchymal (M). Although each of these tumor-specific subtypes represent different gene expression profiles, response to standard treatments and prognosis, further studies did not confirm a prognostic value for these subtypes. Given the distinct outcomes of TNBC patients, there is an urgent need to stratify their prognosis and identify patients who may benefit from potential targeted therapy. TNBC tumors often harbor cancer cells with different features in both genomic and transcriptomic level. With deconvolution of existing genomic and transcriptomic data, we derived a mathematical definition of breast cancer cell plasticity at a patient level. With a total of 765 TNBC patients from The Cancer Genome Atlas (TCGA), Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), Fudan University Shanghai Cancer Center (FUSCC) and Sweden Cancerome Analysis Network-Breast project (SCAN-B), we measured tumor-cell total mRNA expression scores (TmS) through an integrative deconvolution method with matched DNAseq and RNAseq data. In our previous study (Cao et al. Nature Biotechnology 2022), high TmS value is significantly associated with favorable prognosis in both TCGA (n=108) and METABRIC (n=214). We now validated this finding in both FUSCC from Han Chinese (n=245) and SCAN-B from Swedes (n=198). With TmS as a patient-level phenotypic feature, we performed differential expression analysis and gene set enrichment analysis to understand the biological functions indicated by TmS. In all four TNBC cohorts, patients with lower TmS are associated with epithelial to mesenchymal and TGFβ signaling hallmark pathways, with the latter presenting potential molecular targets for TNBC. Gene ontology enrichment revealed patients with higher TmS overexpress genes that are related with immune activities such as B cell and lymphocyte activation. Our results suggest a unique utility of tumor-specific total mRNA level in identifying high-risk TNBC patients across multi-ethnic cohorts and tailoring treatment on individual basis to maximize clinical benefit. Citation Format: Yaoyi Dai, Shaolong Cao, Bora Lim, Johan Staaf, Gloria V. Echeverria, Wenyi Wang. Tumor cell total mRNA level predicts disease progression across multi-ethnic patient cohorts with triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3311.

Abstract PD1-06: Black patients with triple negative breast cancer (TNBC) have enriched stromal tumor infiltrating lymphocytes (sTILs) and receive preferential benefit from neoadjuvant immunotherapy

Abstract Introduction TNBC is overrepresented in Black women, and Black patients with TNBC have worse clinical outcomes compared to non-Black patients. This disparity likely results from racial differences in clinical, biological, and demographic features of TNBC and social determinants of health. Neoadjuvant chemoimmunotherapy is current standard of care for high-risk TNBC. However, Black patients have been poorly represented in immunotherapy TNBC trials, making it difficult to assess comparative efficacy of immunotherapy in Black patients. Methods We utilized two TNBC neoadjuvant trials to assess racial differences in the tumor immune microenvironment composition and evaluate impact of race on response to chemotherapy vs chemoimmunotherapy. NeoSTOP trial (NCT02413320) randomized 100 stage I-III TNBC patients to receive neoadjuvant carboplatin/paclitaxel + doxorubicin/cyclophosphamide (CbP+AC) or carboplatin/docetaxel (CbD). NeoPACT trial (NCT03639948) enrolled 120 patients with stage I-III TNBC who received neoadjuvant CbD + pembrolizumab (CbD+P). sTILs were centrally quantified, and RNA extracted from pretreatment tissue was subjected to next-generation sequencing. Relative leukocyte fractions were computed by CIBERSORTx. Factors were tested as predictors of pathologic complete response (pCR) using logistic regression analysis. Event-free survival (EFS) was estimated by the Kaplan-Meier method and compared between groups by log-rank test, followed by Cox regression analysis. Results The study population includes 197 patients with known race, sTILs, and gene expression data (84 patients from NeoSTOP, 113 from NeoPACT). 15/84 (18%) patients in NeoSTOP and 20/113 (18%) patients in NeoPACT self-reported Black race. There was no significant difference in age, T or N stage, or germline BRCA1/2 mutation status by race in either study. Black patients had significantly higher sTILs than non-Black patients (median 40% vs 15%, P=0.048) and were more likely to have ≥20% sTILs than non-Black patients (66% vs 44%, P=0.026). There was no significant difference in pCR by race in NeoSTOP (OR=0.60, 95% CI 0.19-1.84, P=0.37; pCR 47% for Black vs 59% for non-Black). In contrast, in NeoPACT, Black patients had a significantly higher pCR compared to non-Black patients (OR=3.27, 95% CI 1.01-10.64, P=0.049; pCR 79% for Black vs 53% for non-Black). In NeoSTOP, EFS was similar for Black and non-Black patients (3-year EFS 92% and 94%, respectively, HR=0.88, 95% CI 0.11-7.28, P=0.90). In NeoPACT, EFS was numerically higher in Black vs non-Black patients (3-year EFS 93% and 81%, respectively, HR=0.43, 95% CI 0.05-3.36, P=0.40); NeoPACT survival follow-up is ongoing at the time of this report. On CIBERSORTx analysis, Black patients had relative depletion of immunosuppressive pro-tumorigenic M2 macrophages (P=0.005) and CD4+ memory resting T cells (P=0.021) compared to non-Black patients. Conclusions Compared to non-Black patients, Black patients with TNBC are more likely to have immune-enriched tumors with lower relative abundance of immunosuppressive leukocytes. These findings suggest potential for higher relative magnitude of benefit from checkpoint inhibitor therapy in Black compared to non-Black patients. Supporting this biological hypothesis, we noted that Black and non-Black patients had equivalent rates of pCR with neoadjuvant chemotherapy; however, pCR rate among Black patients was significantly higher than in non-Black patients when treated with neoadjuvant chemoimmunotherapy. These findings should be confirmed in other studies and can optimize utilization of neoadjuvant chemoimmunotherapy. Our findings also underscore the importance of efforts to address disparity in access and use of immunotherapy in Black patients. Citation Format: Shane R. Stecklein, Rachel Yoder, Roberto Salgado, Joshua M. Staley, Anne O’Dea, Lauren Nye, Manana Elia, Deepti Satelli, Gregory Crane, Richard McKittrick, Andrew K. Godwin, Qamar Khan, Priyanka Sharma. Black patients with triple negative breast cancer (TNBC) have enriched stromal tumor infiltrating lymphocytes (sTILs) and receive preferential benefit from neoadjuvant immunotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-06.

Abstract PD2-08: Targeting of eIF4A1 along with anti-PD-L1 therapy limits lung metastases efficaciously in triple-negative breast cancer

Abstract Background: Triple-negative breast cancer (TNBC) is the most aggressive subtype of metastatic breast cancer with poor clinical prognosis. Currently used neoadjuvant chemotherapy for TNBC, such as taxanes, and/or anthracyclines demonstrate an initial treatment response but is often followed by drug resistance, tumor relapse, and high proclivity to develop metastases. There is an unmet need to develop effective combination therapies against metastatic TNBC (mTNBC). eIF4A1 is an mRNA helicase that help translate many oncogenic mRNAs including PD-L1 (through STAT1 translational regulation) that are involved in tumor growth, chemoresistance and metastases. Our prior studies pointed out that eIF4A1 is intricately linked to cancer stemness and drug resistance in TNBC. Emerging evidence has revealed that the tumor immune microenvironment (TIME) of TNBC do consist of mononuclear cells and lymphocytes. Combining chemotherapy with immune checkpoint inhibition had demonstrated a significant benefit for high-risk TNBC patients. In this study, we examine the efficacy of targeting eIF4A1 along with anti-PD-L1 therapy as an effective therapeutic strategy to limit cancer stemness, primary tumor progression and metastasis in an immunocompetent murine model of TNBC. Approach: Initially, we examined the human TNBC biospecimens and found that eIF4A1 protein level is upregulated in drug-resistant cases. STAT1 is an upstream regulator of PD-L1 and a downstream effector of eIF4A1. The protein level of STAT1 was significantly elevated as assessed by immunoblotting of human tumor lysates. In human TNBC cells, when eIF4A1 is pharmacologically or genetically targeted, PD-L1 was downregulated at the protein level. Based on this premise, we targeted eIF4A1 with the small molecule inhibitor, Rocaglamide A (RocA), along with anti-PD-L1 immunotherapy in orthotopically implanted 4T1 mouse TNBC tumors in BALB/c mice. The treatment arms were 1) Control (vehicle for RocA + control IgG) 2) RocA 3) RocA + anti-PD-L1 antibodies 4) Control IgG only 5) Anti-PD-L1 antibodies only with 10 mice in each group. Results: The combination treatment comprising of RocA and anti-PD-L1 antibodies worked out efficaciously as the primary tumor volume, wet tumor weight, bioluminescent tumor imaging and quantitation were significantly lower than the combination vehicle control. Furthermore, metastasis to the lungs were significantly impaired (1 out of 10 mice only had metastasis and that too it was small). On the contrary, ‘RocA single arm’ group had 6 out of 10 mice with lung metastasis. The lung metastases were observed in 4 out of 10 mice in the PD-L1 single arm and 6 out of 10 mice in control IgG single arm group. The RocA was tolerated well at 0.6 mg/kg with no significant change in the body weight and the liver and kidney function test values were within the normal range. Importantly, the combination treatment with RocA and PD-L1 was also tolerated well. Conclusions: The combination therapy involving RocA and PD-L1 had the significant impact in reducing lung metastases and may pave the way for phase I/II clinical trials. Citation Format: Dharmindra Dulal, Andrew Boring, Dayanidhi Raman. Targeting of eIF4A1 along with anti-PD-L1 therapy limits lung metastases efficaciously in triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD2-08.

Neoadjuvant checkpoint blockade in combination with Chemotherapy in patients with tripe-negative breast cancer: exploratory analysis of real-world, multicenter data

PurposeDespite the poor prognosis of triple-negative breast cancer (TNBC), it has been demonstrated that neoadjuvant immunotherapy in combination with chemotherapy can improve the pathologic complete response (pCR) rate and/or long-term outcome of TNBC. However, there have been no real-world studies reporting on the effectiveness of neoadjuvant checkpoint inhibitors in early TNBC.MethodsBetween November 2019 and December 2021, 63 early TNBC patients treated with anti-PD-1 antibodies (pembrolizumab or camrelizumab) or anti-PD-L1 antibody (atezolizumab) in combination with chemotherapy at seven institutions were included. PCR1 defined as ypT0/Tis and ypN0 was the primary endpoint. Secondary endpoints included pCR2 defined as ypT0/Tis, overall response rate (ORR), disease-free survival (DFS), drug-related adverse events (AEs) and biomarkers.ResultsAmong the patients in the current study, 34.9% of patients were able to achieve pCR1, and 47.6% of patients had achieved pCR2. The ORR was 82.5%. 33 patients with non-pCR2 tumors were found to have a median DFS of 20.7 months (95% CI 16.3 months-not reached). The DFS of patients with pCR2 and non-pCR2 after neoadjuvant therapy was significantly different (HR = 0.28, 95% CI 0.10–0.79; P = 0.038). The most common AEs were nausea (63.4%), fatigue (42.7%), leucopenia (30.0%) and elevated transaminase (11.7%).ConclusionIt is possible to achieve a meaningful pCR rate and DFS by combining neoadjuvant checkpoint blockade with chemotherapy in patients with high-risk TNBC. Compared to clinical trials, however, there was a slightly lower pCR rate in this multicentered real-world study.

Comparison of Programmed Cell Death Ligand 1 Status between Core Needle Biopsy and Surgical Specimens of Triple-Negative Breast Cancer.

Pembrolizumab is currently used to treat advanced triple-negative breast cancer (TNBC) and high-risk early TNBC with neoadjuvant chemotherapy (NAC). The tumor-infiltrating lymphocyte (TIL) level and programmed cell death ligand 1 (PD-L1) status are predictors of response to NAC and immune checkpoint inhibitor treatment. We aimed to investigate whether the PD-L1 status in core needle biopsies (CNBs) could represent the whole tumor in TNBC. A total of 49 patients diagnosed with TNBC who received upfront surgery without NAC between January 2018 and March 2021 were included. The PD-L1 expression (SP142 and 22C3 clones) and TIL were evaluated in paired CNBs and resected specimens. The concordance PD-L1 status and TIL levels between CNBs and resected specimens were analyzed. PD-L1 positivity was more frequently observed in resected specimens. The overall reliability of TIL level in the CNB was good [intraclass correlation coefficient (ICC)=0.847, p<0.001]. The agreements of PD-L1 status were good and fair, respectively (SP142, κ=0.503, p<0.001; 22C3, κ=0.380, p=0.010). As the core number of CNB increased, the reliability and agreement also improved, especially from five tumor cores (TIL, ICC=0.911, p<0.001; PD-L1 [22C3], κ=0.750, p=0.028). Regarding PD-L1 (SP142), no further improvement was observed with ≥5 tumor cores (κ=0.600, p=0.058). CNBs with ≥5 tumor cores were sufficient to represent the TIL level and PD-L1 (22C3) status in TNBC.

Identification and Validation of a Novel Glycolysis-Related Gene Signature for Predicting the Prognosis and Therapeutic Response in Triple-Negative Breast Cancer.

A high malignancy rate and poor prognosis are common problems with triple-negative breast cancer (TNBC). There is increasing evidence that glycolysis plays vital roles in tumorigenesis, tumor invasion, immune evasion, chemoresistance, and metastasis. However, a comprehensive analysis of the diagnostic and prognostic significance of glycolysis in TNBC is lacking. Transcriptomic and clinical data of TNBC patients were obtained from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) databases, respectively. Glycolysis-related genes (GRGs) were collected from the Molecular Signatures Database (MSigDB). Differential comparative analysis was performed to obtain the differentially expressed (DE)-GRGs associated with TNBC. Based on the DE-GRGs, a glycolysis-related risk signature was established using Least Absolute Shrinkage and Selector Operation (LASSO) and multivariable Cox regression analyses. The prognostic value, tumor microenvironment, mutation status, and chemotherapy response of different risk groups were analyzed. An independent cohort from the METABRIC database was used for external validation. Furthermore, the expression patterns of five genes derived from the prognostic model were validated by quantitative real-time polymerase chain reaction (RT-qPCR). The glycolysis-related prognostic signature included five genes (IFNG, ACSS2, IRS2, GFUS, and GAL3ST1) and predicted the prognosis of TNBC patients independent of clinical factors (p < 0.05). Patients were divided into high- and low-risk groups based on the median risk score. Compared to low-risk TNBC patients, high-risk patients had significantly decreased overall survival (HR = 2.718, p < 0.001). Receiver operating characteristic and calibration curves demonstrated that the model had high performance in terms of predicting survival and risk stratification. The results remained consistent after external verification. Additionally, the tumor immune microenvironment significantly differed between the risk groups. Low-risk TNBC patients had a better immunotherapy response than high-risk patients. High-risk TNBC patients with a poor prognosis may benefit from targeted therapy. This study developed a novel glycolysis and prognosis-related (GRP) signature based on GRGs to predict the prognosis of TNBC patients, and may aid clinical decision-making for these patients.

A Phase I Study of Adjuvant Niraparib Administered Concurrently with Postoperative Radiation Therapy in Patients with Localized Triple Negative Breast Cancer

<h3>Purpose/Objective(s)</h3> Residual disease after neoadjuvant therapy (NAT) is associated with higher risk of recurrence, including local failure (25%) in triple negative breast cancer (TNBC). Novel combinations that increase the efficacy of standard-of-care treatments on locoregional control are warranted. PARP inhibitors (PARPi) target the DNA damage repair pathway, which is often altered in TNBC, and show promise as radiosensitizers. The objective of this phase I trial (NCT03945721) was to determine the maximum tolerated dose (MTD) of a PARPi, niraparib, in pts with high risk TNBC receiving postoperative radiotherapy (RT). <h3>Materials/Methods</h3> Eligible pts had stage I-III TNBC with residual invasive disease following NAT or primary tumor ≥1 cm after upfront surgery. A 3+3 escalation design was used to test 2 dose levels of QD niraparib (100mg, 200mg) with concurrent RT to the chest wall or breast +/- regional lymph nodes over 4-6 weeks. Dose expansion followed at the MTD. A boost was delivered in pts who had lumpectomy. 2 pts received proton beam RT. Bolus was administered in postmastectomy RT or in cases of dermal lymphatic invasion. Circulating tumor DNA (ctDNA) was collected at baseline, mid-RT, end of RT, and 30 days post-RT to assess the kinetics of ctDNA levels during RT and the association with clinical outcomes. Adverse events (AEs) were assessed using CTCAE v5.0. <h3>Results</h3> 21 pts were enrolled from July 2019 – October 2021. The median age was 49 (31-69). 19/21 pts had residual disease after NAT (6 RCB I, 7 RCB II, 6 RCB III); among them, 2 underwent adjuvant chemotherapy prior to enrolling. The remaining 2/21 pts (pT2N0; pT1cN0) received upfront breast conserving surgery followed by adjuvant chemotherapy. In dose escalation, 6 pts received 100mg niraparib + RT and 2 pts received 200mg niraparib + RT. One DLT in the 100mg cohort (G3 dermatitis) was attributed to RT. Two DLTs in the 200mg cohort (G3 thrombocytopenia) were attributed to niraparib and study drug was discontinued. In dose expansion, 13 pts received 100mg niraparib + RT. G3 AEs were dermatitis (4/21), hematologic (4/21), consisting of thrombocytopenia, anemia & lymphopenia, and elevated alkaline phosphatase (1/21). There was one G4 thrombocytopenia. All skin AEs were attributed to RT and were not exacerbated by niraparib. No pts in dose expansion discontinued treatment due to toxicity. 20/21 went on to standard-of-care capecitabine after completing RT. Results of ctDNA will be reported at the meeting. <h3>Conclusion</h3> The MTD of niraparib + postop RT was determined to be 100mg QD and was associated with a 24% rate of G3-4 hematologic toxicities and 19% rate of G3 radiation dermatitis in pts with localized TNBC, which is within upper limits of normal for pts in whom chest wall/skin is targeted. These results will be informative for a future larger study testing the efficacy of niraparib + postop RT in high risk TNBC.