Early Triple-negative Breast Cancer Research Articles

Abstract P4-02-09: The lncRNA XIST mediates sensitivity to ERβ targeted therapies in triple negative breast cancer

Abstract Background:. Poor patient outcomes in triple negative breast cancer (TNBC) largely stem from a lack of understanding of therapeutic vulnerabilities and an insufficient armamentarium of effective drugs. The standard of care for most early stage TNBC patients continues to be (neo)adjuvant chemotherapy and radiation. Identifying additional therapeutic options for this subset of patients represents a major unmet need. We and others demonstrated that estrogen receptor beta (ERβ) is expressed in about 20% of TN tumors. Prior research has shown that ligand-mediated activation of ERβ decreases proliferation, invasion, and migration in TNBC cell lines. In vivo, ERβ suppresses the growth of cell line xenograft models and prevents the development of metastatic lesions in a ligand dependent manner. Mechanistically, we found that ERβ repurposes EZH2 to suppress oncogenic NFκB signaling and that pharmacologic inhibition of EZH2 diminishes ERβ function and its anti-cancer effects. This research has led to an ongoing clinical trial (NCT03941730) assessing the efficacy of estradiol in ERβ+ TNBC patients with chemorefractory disease. As with all therapies, patients will exhibit de novo and acquired resistance and therefore we sought to understand the mechanisms of resistance to ERβ targeted therapies. Methods:. Using multiple models of ERβ positive TNBC, we developed ERβ resistant cell lines through chronic exposure to estradiol and the ERβ specific agonist LY500307 over a period of 8 months. We employed RNA sequencing to characterize the transcriptomic changes which occurred following ERβ resistance. We profiled XIST expression across multiple publicly available datasets, including TCGA, Metabric, BEAUTY, and GTEx. XIST expression was also modulated using CRISPR/Cas9 to assess subsequent effects on TNBC cell biology, ERβ function, and response to ERβ targeted therapies. Results:. Our resistant cell line models of ERβ positive TNBC maintained ERβ expression, but were no longer growth inhibited by ERβ agonists. RNAseq revealed substantial differences comparing the transcriptome of resistant versus sensitive cell lines, of which the most increased transcript in the resistant setting was the lncRNA XIST. XIST is best known for its role in X-chromosome inactivation through recruitment and association with the PRC2 complex, and thus EZH2. However, little is known about its functions in breast cancer. We therefore assessed the expression levels of XIST in breast tumors and cell lines. XIST expression was highly variable in breast cancer, was found in a proportion of all breast cancer sub-types and did not correlate with ERβ status. However, XIST expression was up-regulated in ERβ expressing cell lines following long term estrogen treatment. No effects on XIST expression were identified in multiple ERα positive models following estrogen, SERM/SERD treatment, or estrogen deprivation. Furthermore, upregulation of XIST was not associated with resistance to Paclitaxel or Doxorubicin, suggesting XIST is not a part of a broad resistance phenotype. Strikingly, CRISPR mediated knockout of XIST in ERβ resistant cells completely re-sensitized cells to ERβ targeted therapies suggesting that XIST expression is a critical component of ERβ resistance. Conclusions:. ERβ represents a relevant therapeutic target that is being tested in clinical trials. Using multiple in vitro models, we provide evidence that XIST expression is sufficient to induce resistance to. ERβ targeted therapies in TNBC and may therefore represent a relevant biomarker for patient stratification. Further strategies to suppress XIST expression may elicit anti-cancer effects on their own and may resensitize a sub-set of ERβ resistant tumors to ERβ agonists. Citation Format: Michael J Emch, Kirsten GM Aspros, Elizabeth S Bruinsma, Krishna R Kalari, Calley J Jones, Brandon W Simone, Matthew P Goetz, John R Hawse. The lncRNA XIST mediates sensitivity to ERβ targeted therapies in triple negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-02-09.

Abstract ES10-2: Immune therapy in the (neo) adjuvant setting

Abstract Historically, the treatment of early-stage triple negative breast cancer (TNBC) has hinged on the administration of conventional cytotoxics. However, the curative-intent treatment landscape has recently evolved with the successful development of checkpoint blockade inhibitor (CPI) strategies. Specifically, on July 27, 2021, the United States FDA approved the PD-1 directed antibody, pembrolizumab, for high-risk early-stage TNBC together with chemotherapy as neoadjuvant treatment and then continued as a single agent as adjuvant treatment after surgery based on the results of the randomized, phase 3 KEYNOTE-522 study. In this study, the addition of pembrolizumab to a platinum-, taxane- and anthracycline-based regimen conferred an absolute 13.6% improvement in pathologic complete response (pCR) in the intention-to-treat population at the first interim analysis, with benefits observed irrespective of PD-L1 status. Although the absolute benefit subsequently decreased to 7.5% at the third interim analysis, the event free survival (EFS) benefit was maintained. In fact, with a median follow-up of 39.1 months at the fourth interim analysis, the EFS was 15.7% versus 23.8% (HR 0.63, p= 0.00031) in favor of the CPI containing regimen. The Geparnuevo study, a modestly powered study in which randomized patients with early stage TNBC to receive neoadjuvant chemotherapy with or without durvalumab, a PD-L1 targeting CPI, did not meet its pCR primary endpoint; however, in a recent update reporting on secondary endpoints, improvements in invasive disease free survival (85.6% vs 77.2%), distant disease free survival (91.7% vs 78.4%) and overall survival (95.2% vs 83.5%) were reported in favor of the CPI-containing regimen. EFS data from the IMpassion031 study of neoadjuvant chemotherapy with or without the PD-L1 targeting CPI, atezolizumab, are anticipated after an absolute 16.5% improvement in pCR was reported in the intention-to-treat population with the addition of the CPI, with benefits observed regardless of PD-L1 status. Studies evaluating the role of CPI strategies in the adjuvant setting are also underway. For example, pembrolizumab is being evaluated as monotherapy for patients with residual TNBC after neoadjuvant chemotherapy in the SWOG 1418 study and atezolizumab is being administered with adjuvant chemotherapy after upfront surgery for early-stage TNBC in the IMpassion030/ALEXANDRA study. Studies evaluating curative-intent CPI and targeted therapies and/or local therapies are underway or planned. Available data, current controversies and future directions will be discussed. Citation Format: H McArthur. Immune therapy in the (neo) adjuvant setting [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr ES10-2.

Abstract P1-19-03: Phase II trial of durvalumab and tremelimumab in the hormone receptor-positive metastatic breast cancer with high tumor mutational burden selected by whole exome sequencing: Korean cancer study group trial (KCSG BR17-04)

Abstract Background: Hormone-receptor (HR) positive breast cancer is the main subtype of breast cancer. Although overall survival of HR-positive metastatic breast cancer (MBC) patients has improved by various therapies including endocrine therapies, CDK4/6 inhibitors, and cytotoxic chemotherapy, it is still considered incurable. Immune checkpoint inhibitors have rarely been clinically tested in HR-positive breast cancer, despite proving anti-cancer activity in early and metastatic triple-negative breast cancer in various trials. We evaluated efficacy and safety of combined durvalumab and tremelimumab in the HR-positive MBC, which was enriched with high tumor mutational burden (TMB). Methods: HR-positive MBC patients who received prior 1 or more lines of therapy in metastatic setting were prescreened with whole exome sequencing (WES) using metastatic or recurred tumor biopsies. Criterion of high TMB was defined as upper 30%. In the beginning, the criterion of high TMB was 2.1 mutations per Mb, based on the retrospective WES database in Yonsei Cancer Center and this criterion was recalculated every 30 cases. Patients who met upper 30% of TMB were treated with combined durvalumab (1500mg every 4 weeks upto 13 doses) and tremelimumab (75mg every 4 weeks upto 4 doses). Response was evaluated every 2 cycles using RECIST 1.1 and toxicity was evaluated using NCI-CTCAE 4.03. Tumor-infiltrating lymphocyte (TIL) and PD-L1 expression were also analyzed to investigate a correlation with TMB. Results: Biopsies of recurrent or metastatic tumors were taken from a total of 119 patients for WES assay. A median turn-around-time of TMB data was 30.0 days (range, 16~67). Of these 119 patients, a median number of nonsynonymous mutations was 2.0 per Mb (range, 0~21.7) with upper 30% criterion of 3.1. High TMB showed a trend toward old age (P=0.074) and single positivity of estrogen receptor (ER) or progesterone receptor (PR) compared to positivity of both ER and PR (P=0.055). TMB was positively correlated with TILs (r=0.289, P=0.005). Thirty patients with high TMB received study treatment with a median 2 cycles (range, 1~13). A median prior lines of therapies in metastatic setting was 4 (range, 1~9). The objective response and clinical benefit rates were 6.3% (2 PRs of 30) and 20% (2 PRs plus 4 SDs of 30). There was one treatment-related mortality due to pneumonitis. Immune-related adverse events included endocrinopathy (n=3; hypothyroidism in 2, hyperthyroidism in 1), enteritis (n=2), skin rash (n=2), pneumonitis (n=1), and so on. Biomarker analyses are underway. Conclusions: WES-based TMB using metastatic tumor biopsy was a feasible platform to prescreen HR-positive MBC patients. Combined durvalumab and tremelimumab showed a modest activity and good tolerability in heavily treated, HR-positive MBC with high TMB. Citation Format: Yong Wha Moon, Eunyoung Kim, Min Hwan Kim, Gun Min Kim, Seul-Gi Kim, YeeSoo Chae, Jieun Lee, Jae Ho Jeong, Kyung-Hun Lee, Han Jo Kim, Joo Young Jung, Su-Jin Koh, Kyoung Eun Lee, Hee-Jun Kim, Kyong Hwa Park, Seungtaek Lim, Yeon Hee Park, Tae Hoen Kim, Sewha Kim, Yohan Yang, Sangwoo Kim, Joohyuk Sohn. Phase II trial of durvalumab and tremelimumab in the hormone receptor-positive metastatic breast cancer with high tumor mutational burden selected by whole exome sequencing: Korean cancer study group trial (KCSG BR17-04) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-19-03.

Abstract GS1-00: Single-cell spatial analysis by imaging mass cytometry and immunotherapy response in triple-negative breast cancer (TNBC) in the NeoTRIPaPDL1 trial

Abstract Background Immunecheckpoint inhibitors are effective in early and advanced TNBC, however only aminority of patients benefit making precision immune-oncology a major unmetneed. Imaging mass cytometry (IMC) enables high dimensional tissue imaging atsubcellular resolution for assessment of TNBC ecosystems, providing informationon cell type composition, functional status, and spatial organisation. Methods InNeoTRIP patients with TNBC were randomized to eight cycles ofnab-paclitaxel/carbo (CT) with/without atezolizumab (CTA). Forty-four proteinsspanning cancer cells and the tumor microenvironment (TME) were assessed onpre-treatment biopsies (n=243/280; 86.8% evaluable after QC). FFPE samples werelabelled with antibodies conjugated to isotopically pure rare earth metalreporters and profiled at one micron resolution by IMC. For each sample, wehave generated three high dimensional images that encompass the tumor,tumor-stroma interface and adjacent stroma. We investigated the association ofprotein expression assessed separately for epithelial and TME cells, cellphenotypes, and spatial architectures with PD-L1 status (Ventana SP142),stromal TILs, TNBC types and pathological complete response (pCR). 237 patients(84.6%) have both IMC and RNA-seq available allowing for comparison with genesignatures derived from HALLMARK,ConsensusTME immune cell types, and Nanostring. Results Across243 samples we identify just over one million single cells. By supervised clustering,we defined 37 robust cell phenotypes. PD-L1-positive tumors, high stromal TILsand TNBC type were characterized by extreme heterogeneity and unique cell-type andspatial TME composition. Severalbiomarkers demonstrated a significant test for interaction. Considering proteinexpression, GATA3 and CD20 on TME, HLA-DR in epithelial cells and Ki67 assessedboth in epithelial and TME, had a significant test for interaction (p <0.05). For all these biomarkers, high expression (above median) was associatedwith an increase of pCR of >10% in favour of atezolizumab, whereas lowerexpression group demonstrated a similar pCR rate among arms.Two cellphenotypes, PD-L1+IDO+ antigen presenting cells (APCs) and CD56+ neuroendocrine(NE) epithelial cells, had a significant test for interaction. Higherexpression of these biomarkers was associated with higher likelihood of pCR in CTAarm, but not in CT arm. For example, PD-L1+IDO+APCs in the CTA arm wereassociated with pCR proportions of 64.6% and 24.6% for above- and below-mediangroups respectively (OR4.5 [2.01-10.1], p<0.001).Mostof these tests of interaction retained significance after adjustment by PD-L1status and stromal TILs. Notably, none among 61 gene-expression basedimmune-related pathways and 7 proliferation-related signatures demonstrated a significant test ofinteraction. Resultsof systematic multi-tiered image analysis at the levels of cell-cellinteractions and recurrent higher order multicellular complexes defining TNBC ecosystemsidentified by graph-based methods will be presented at the meeting. Conclusions Imaging mass cytometry provides a morecomprehensive overview of TNBC heterogeneity at a single-cell level withspatial resolution. Bulk protein or gene expression might deliver limitedpredictive information because it does not consider the cell compartment ofexpression. Precise cell phenotyping highlights the predictive role ofPD-L1+IDO+APCs and CD56+NE epithelial cells. Overall, we demonstrated that IMCis feasible in a large, randomized trial and provides independent predictiveinformation on immune checkpoint inhibitors benefit to PD-L1, TILs and gene-expressionprofiles. Citation Format: Giampaolo Bianchini, Xiao Qian Wang, Esther Danenberg, Chiun-Sheng Huang, Daniel Egle, Maurizio Callari, Begoña Bermejo, Claudio Zamagni, Marc Thill, Anton Anton, Matteo Dugo, Stefania Zambelli, Stefania Russo, Eva Maria Ciruelos, Richard Greil, Vladimir Semiglazov, Marco Colleoni, Catherine Kelly, Gabriella Mariani, Lucia Del Mastro, Balázs Győrffy, Olivia Biasi, Pinuccia Valagussa, Giuseppe Viale, Luca Gianni, H Raza Ali. Single-cell spatial analysis by imaging mass cytometry and immunotherapy response in triple-negative breast cancer (TNBC) in the NeoTRIPaPDL1 trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-00.

Abstract P2-12-05: Efficacy of neoadjuvant systemic carboplatin therapy in triple-negative breast cancer

Abstract Background. Guidelines recommend broad use of carboplatin (CBDCA) for neoadjuvant therapy (NACT) of patients with triple negative breast cancer (TNBC). However, current evidence is contradictory. The aim of this prospective observational study was to assess efficacy and feasibility of CBDCA-containing neoadjuvant therapy in clinical routine. Patients and Methods. Patients who received NACT for early TNBC (n=150) were consecutively enrolled between 2000 and 2021. The following regimens were used: dose-dense epirubicin-cyclophosphamide (ddEC) followed by taxanes (n=62); CBDCA-taxane combination followed by ddEC (n=49), CBDCA-taxane combination, no anthracyclines (n=25), other chemotherapy regimen (n=14). Some CBDCA therapies were given every 3 weeks (n=18), the majority was given in a weekly fashion (n=56). The efficacy and feasibility including toxicities of these carboplatin regimen were analyzed. Median follow-up iDFS: 36.2 months (6-154), median Follow-up OS 39.3 months (6-214).Primary objective was the pCR rate (ypT0 N0) in patients who were treated with CBDCA in comparison to those who received standard non-platinum containing NACT. Secondary objectives were toxicity, therapy adherence, cancer associated recurrences and association of pCR rate with invasive disease-free survival (iDFS) and overall survival (OS). Results. Half of the patients (n=74) were treated with CBDCA, two third (69%) of them received the complete intended cycles if necessary with primary GCSF-support. Overall, the addition of CBDCA slightly increased the pCR rate from 43.4% to 48.6% with a 1.8 times reduced risk for iDFS events. The highest pCR rate was observed in those patients (n=50) who had received all CBDCA-courses as planned (50% vs 45%). By 48 months, pCR with CBDCA treatment was associated with an improved course of the disease (86.3 % iDFS probability), followed by non-pCR and CBDCA-therapy (81.1% iDFS probability), pCR and no platinum (79.8%) and non-pCR and no platinum (70.7%). Considering OS, patients without CBDCA and no pCR had the highest mortality (19.5%), all other groups had over 90% OS-probability. Dose-modification of CBDCA was associated to pCR (4 of 5 patients), whilst with discontinuation of CBDCA, 12 of 20 patients had residual disease. Although neutropenia, thrombocytopenia or anemia occurred in 36 patients, CBDCA discontinuation due to hematological effects was only necessary in 10 cases. Conclusion. In our prospective cohort, the addition of CBDCA to neoadjuvant chemotherapy for patients with TNBC was highly effective. Even after dose-modification of CBDCA (e.g. for toxicity) it seems to be effective compared to discontinuation or no inclusion of CBDCA. Our data support the current recommendations to include CBDCA in neoadjuvant therapy for TNBC. Citation Format: Christoph Thomssen, Kathleen Schüler, Marcus Bauer, Kristin Reinhardt, Hans-Gerorg Strauß, Martina Vetter. Efficacy of neoadjuvant systemic carboplatin therapy in triple-negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-05.

Event-free Survival with Pembrolizumab in Early Triple-Negative Breast Cancer

BackgroundThe addition of pembrolizumab to neoadjuvant chemotherapy led to a significantly higher percentage of patients with early triple-negative breast cancer having a pathological complete response (defined as no invasive cancer in the breast and negative nodes) at definitive surgery in an earlier analysis of this phase 3 trial of neoadjuvant and adjuvant therapy. The primary results regarding event-free survival in this trial have not been reported.MethodsWe randomly assigned, in a 2:1 ratio, patients with previously untreated stage II or III triple-negative breast cancer to receive neoadjuvant therapy with four cycles of pembrolizumab (at a dose of 200 mg) or placebo every 3 weeks plus paclitaxel and carboplatin, followed by four cycles of pembrolizumab or placebo plus doxorubicin–cyclophosphamide or epirubicin–cyclophosphamide. After definitive surgery, patients received adjuvant pembrolizumab (pembrolizumab–chemotherapy group) or placebo (placebo–chemotherapy group) every 3 weeks for up to nine cycles. The primary end points were pathological complete response (the results for which have been reported previously) and event-free survival, defined as the time from randomization to the date of disease progression that precluded definitive surgery, local or distant recurrence, occurrence of a second primary cancer, or death from any cause. Safety was also assessed.ResultsOf the 1174 patients who underwent randomization, 784 were assigned to the pembrolizumab–chemotherapy group and 390 to the placebo–chemotherapy group. The median follow-up at this fourth planned interim analysis (data cutoff, March 23, 2021) was 39.1 months. The estimated event-free survival at 36 months was 84.5% (95% confidence interval [CI], 81.7 to 86.9) in the pembrolizumab–chemotherapy group, as compared with 76.8% (95% CI, 72.2 to 80.7) in the placebo–chemotherapy group (hazard ratio for event or death, 0.63; 95% CI, 0.48 to 0.82; P<0.001). Adverse events occurred predominantly during the neoadjuvant phase and were consistent with the established safety profiles of pembrolizumab and chemotherapy.ConclusionsIn patients with early triple-negative breast cancer, neoadjuvant pembrolizumab plus chemotherapy, followed by adjuvant pembrolizumab after surgery, resulted in significantly longer event-free survival than neoadjuvant chemotherapy alone. (Funded by Merck Sharp and Dohme, a subsidiary of Merck; KEYNOTE-522 ClinicalTrials.gov number, NCT03036488.)

Is breast conservation superior to mastectomy in early stage triple negative breast cancer?

PurposeCompare overall survival (OS) and breast cancer-specific survival (BCSS) outcomes of breast conservative therapy (BCT) and mastectomy in a large cohort of patients with early-stage triple negative breast cancer (TNBC), using a propensity score-based matching approach.MethodsSurveillance, Epidemiology, and End Results (SEER) database was used to study the role of RT in early stage TNBC. Primary end points were OS and BCSS. Cox proportional hazard regression models and Kaplan-Meier plots were used to generate the desired outcomes. Propensity score matching was done to minimize bias.Results12,761 patients with T1-2N0M0 TNBC as their first malignancy were retrieved. Of these 7237 had lumpectomy with RT, and 5524 had mastectomy only. Age, race, marital status, tumor laterality, grade and stage, and receipt of chemotherapy were prognostic variables for OS and BCSS. Among 4848 matched subjects, the 5-year OS was significantly higher in patients with lumpectomy and RT (89%) compared to mastectomy alone (84.5%) (p-value <0.001). Similarly, BCSS was significantly higher in patients with lumpectomy and RT (93%) compared to mastectomy alone (91%) (p-value <0.001). On subgroup analysis, patients who are younger than 40 had similar survival outcomes after either mastectomy alone or lumpectomy with RT. However, those who are older than 60, have any grade or T stage had better survival outcomes with lumpectomy and RT.ConclusionsOverall, lumpectomy followed by RT is associated with better OS and BCSS compared to mastectomy in T1-2N0M0 TNBC patients. Further research is needed to determine the optimal treatment strategy for specific patient subgroups.

Comparison of mutational profiles between triple-negative and hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancers in T2N0-1M0 stage: Implications of TP53 and PIK3CA mutations in Korean early-stage breast cancers

Triple-negative breast cancer (TNBC) has higher loco-regional recurrence and visceral metastasis compared to other breast cancer subtypes; however, little is known about the molecular pathogenesis of TNBC. Therefore, we compared the mutation profiles of early TNBC with those of hormone receptor-positive (HR+) and/or human epidermal growth factor receptor 2-negative (HER2−) breast cancer using a customized next-generation sequencing capture panel. DNA was obtained from the primary tumor tissues of 34 patients diagnosed with pT2N0-1M0 HR+/HER2− breast cancer or TNBC. Using SureSelectXT kit (Agilent), next-generation sequencing for 48 breast cancer-associated genes was performed on HiSeq platform (Illumina) with germline confirmation. Also, plasma was collected from 24 patients before surgery, cell-free nucleic acids were extracted, and performed therascreen PIK3CA RGQ PCR assay. Significant mutations were found in TP53, PIK3CA, AR, BRCA1, PTEN, BRCA2, BRIP2, KIT, MET, AKT1, ALK, BARD1, BRAF, CD274, ERBB2, FGFR1, IDH2, NOTCH1, RET, and STK11 (in descending order of occurrence). TP53 mutations were identified in the TNBC group more frequently than in the HR+/HER2− group (P = 0.003). The presence of TP53 mutations was associated with a higher tumor grade (P = 0.008), p53 positivity (P < 0.0001), and a higher Ki-67 index (P = 0.004). PIK3CA was the most frequently mutated gene in HR+/HER2− breast cancer (8/22, 36.4%), but not in TNBC (1/12, 8.3%). The TP53 mutation is associated with higher tumor grade and Ki-67 expression in both groups, and with larger tumor size in TNBC, but not in HR+/HER2– breast cancer. In the foundation of TP53 mutation, concomitant mutation numbers are proportional to tumor size, reflecting clonal progression.

Pembrolizumab vs placebo + chemotherapy as neoadjuvant treatment, followed by pembrolizumab vs placebo as adjuvant treatment for early triple-negative breast cancer (TNBC): Phase 3 KEYNOTE-522 study

Background: KEYNOTE-522 (NCT03036488) is a phase 3 study of pembrolizumab (pembro) + chemotherapy (chemo) vs placebo (pbo) + chemo as neoadjuvant therapy followed by pembro vs placebo as adjuvant treatment in patients (pts) with early TNBC. Pembro + chemo showed a statistically significant improvement in the pCR rate. Pembro + chemo followed by pembro showed a favorable trend in EFS. We present updated results from a prespecified interim analysis of KEYNOTE-522.

Prognostic Value of Metabolic, Volumetric and Textural Parameters of Baseline [18F]FDG PET/CT in Early Triple-Negative Breast Cancer.

Simple SummaryThe aim of this study was to evaluate PET/CT parameters to determine different prognostic groups in TNBC, in order to select patients with a high risk of relapse, for whom therapeutic escalation can be considered. We have demonstrated that the MTV, TLG and entropy of the primary breast lesion could be of interest to predict the prognostic outcome of TNBC patients. (1) Background: triple-negative breast cancer (TNBC) remains a clinical and therapeutic challenge primarily affecting young women with poor prognosis. TNBC is currently treated as a single entity but presents a very diverse profile in terms of prognosis and response to treatment. Positron emission tomography/computed tomography (PET/CT) with 18F-fluorodeoxyglucose ([18F]FDG) is gaining importance for the staging of breast cancers. TNBCs often show high [18F]FDG uptake and some studies have suggested a prognostic value for metabolic and volumetric parameters, but no study to our knowledge has examined textural features in TNBC. The objective of this study was to evaluate the association between metabolic, volumetric and textural parameters measured at the initial [18F]FDG PET/CT and disease-free survival (DFS) and overall survival (OS) in patients with nonmetastatic TBNC. (2) Methods: all consecutive nonmetastatic TNBC patients who underwent a [18F]FDG PET/CT examination upon diagnosis between 2012 and 2018 were retrospectively included. The metabolic and volumetric parameters (SUVmax, SUVmean, SUVpeak, MTV, and TLG) and the textural features (entropy, homogeneity, SRE, LRE, LGZE, and HGZE) of the primary tumor were collected. (3) Results: 111 patients were enrolled (median follow-up: 53.6 months). In the univariate analysis, high TLG, MTV and entropy values of the primary tumor were associated with lower DFS (p = 0.008, p = 0.006 and p = 0.025, respectively) and lower OS (p = 0.002, p = 0.001 and p = 0.046, respectively). The discriminating thresholds for two-year DFS were calculated as 7.5 for MTV, 55.8 for TLG and 2.6 for entropy. The discriminating thresholds for two-year OS were calculated as 9.3 for MTV, 57.4 for TLG and 2.67 for entropy. In the multivariate analysis, lymph node involvement in PET/CT was associated with lower DFS (p = 0.036), and the high MTV of the primary tumor was correlated with lower OS (p = 0.014). (4) Conclusions: textural features associated with metabolic and volumetric parameters of baseline [18F]FDG PET/CT have a prognostic value for identifying high-relapse-risk groups in early TNBC patients.

Current State of Knowledge on the Immune Checkpoint Inhibitors in Triple-Negative Breast Cancer Treatment: Approaches, Efficacy, and Challenges.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with limited treatment options. Recently, there has been a growing interest in immunotherapy with immune checkpoint inhibitors (ICIs) in TNBC, leading to extensive preclinical and clinical research. This review summarizes the current state of knowledge on ICIs efficacy and their predictive markers in TNBC and highlights the areas where the data are still limited. Currently, the only approved ICI-based regimen for TNBC is pembrolizumab with chemotherapy. Its advantage over chemotherapy alone was confirmed for non-metastatic TNBC regardless of programmed death-ligand 1 (PD-L1) expression (KEYNOTE-522) and for metastatic, PD-L1-positive TNBC (KEYNOTE-355). Pembrolizumab’s efficacy was also evaluated in monotherapy, or in combination with niraparib and radiation therapy, showing potential efficacy and acceptable safety profile in phase 2 clinical trials. Atezolizumab + nab-paclitaxel increased the overall survival (OS) over placebo + nab-paclitaxel in early TNBC, regardless of PD-L1 status (IMpassion031). In IMpassion130 (untreated, advanced TNBC), the OS improvement was not statistically significant in the intention-to-treat population but clinically meaningful in the PD-L1 positive cohort. The durvalumab–anthracycline combination showed an increased response durability over placebo anthracycline in early TNBC (GeparNuevo). Several phase 1 clinical trials also showed a potential efficacy of atezolizumab and avelumab monotherapy in metastatic TNBC. ICIs appear to be applicable in both neoadjuvant and adjuvant settings, and are both pretreated and previously untreated patients. Further research is necessary to determine the most beneficial drug combinations and optimize patient selection. It is essential to identify the predictive markers for ICIs and factors affecting their expression.

Impact of stromal tumor-infiltrating lymphocytes (sTILs) on response to neoadjuvant chemotherapy in triple-negative early breast cancer in the WSG-ADAPT TN trial

BackgroundHigher density of stromal tumor-infiltrating lymphocytes (sTILs) at baseline has been associated with increased rates of pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) in triple-negative breast cancer (TNBC). While evidence supports favorable association of pCR with survival in TNBC, an independent impact of sTILs (after adjustment for pCR) on survival is not yet established. Moreover, the impact of sTIL dynamics during NACT on pCR and survival in TNBC is unknown.MethodsThe randomized WSG-ADAPT TN phase II trial compared efficacy of 12-week nab-paclitaxel with gemcitabine versus carboplatin. This preplanned translational analysis assessed impacts of sTIL measurements at baseline (sTIL-0) and after 3 weeks of chemotherapy (sTIL-3) on pCR and invasive disease-free survival (iDFS). Predictive performance of sTIL-0 and sTIL-3 for pCR was quantified by ROC analysis and logistic regression; Kaplan–Meier estimation and Cox regression (with mediation analysis) were used to determine their impact on iDFS.ResultsFor prediction of pCR, the AUC statistics for sTIL-0 and sTIL-3 were 0.60 and 0.63, respectively, in all patients; AUC for sTIL-3 was higher in NP/G. The positive predictive value (PPV) of “lymphocyte-predominant” status (sTIL-0 ≥ 60%) at baseline was 59.3%, though only 13.0% of patients had this status. To predict non-pCR, the cut point sTIL-0 ≤ 10% yielded PPV = 69.5% while addressing 33.8% of patients.Higher sTIL levels (particularly at 3 weeks) were independently and favorably associated with better iDFS, even after adjusting for pCR. For example, the adjusted hazard ratio for 3-week sTILs ≥ 60% (vs. < 60%) was 0.48 [0.23–0.99]. Low cellularity in 3-week biopsies was the strongest individual predictor for pCR (in both therapy arms), but not for iDFS.ConclusionThe independent impact of sTILs on iDFS suggests that favorable immune response can influence key tumor biological processes for long-term survival. The results suggest that the reliability of pCR following neoadjuvant therapy as a surrogate for survival could vary among subgroups in TNBC defined by immune response or other factors. Dynamic measurements of sTILs under NACT could support immune response-guided patient selection for individualized therapy approaches for both very low levels (more effective therapies) and very high levels (de-escalation concepts).Trial registration: Clinical trials No: NCT01815242, retrospectively registered January 25, 2013.

Abstract PO-139: BRCA sequence variants in breast cancer patients with African ancestry

Abstract Introduction Breast cancer is the most common cause of cancer related deaths in women worldwide; however, significant disparities are evident in the epidemiology of breast cancer subtypes and clinical outcomes of different racial/ethnic groups. African Americans are 40% more likely to die from breast cancer—a disparity that is partially explained by genetic predisposition to early onset breast cancer and triple negative breast cancer (TNBC), an aggressive subtype linked to West African ancestry and associated with BRCA-1 germline mutations. Pathogenic BRCA mutations significantly alter breast cancer treatment, informing alternate screening, chemoprevention, prophylactic resections and use of PARB inhibitors; however, AAs have higher prevalence of BRCA variants of uncertain significance (VUS) secondary to underrepresentation of African ancestry in the reference genome. The aim of this study is therefore to further characterize BRCA mutations and BRCA VUS in breast cancer patients with African ancestry. Methods RNA Sequencing platforms were used to determine somatic mutation profiles from primary tumor samples of over 70 breast cancer patients from Ethiopia and Ghana, by identifying single nucleotide polymorphisms (SNPs) in BRCA 1 and 2. Each sequence variant was evaluated for consequence on the gene, previously reported clinical significance, and allele frequency by self-reported race in comparison to global allele frequencies. Results BRCA1: 10 BRCA1 SNPs were identified: Missense: Rs1799966, rs16942, rs16941, rs799917, rs4986850, rs1799950; synonymous: rs1060915, rs16940, rs1799949; variant of 3'UTR: rs3092995. Rs1799966, rs16942, rs16941 and rs1799950 cause deleterious missense mutations, and have been reported as uncertain clinical significance. No SNPs were previously reported pathogenic, 6 had uncertain significance, and 4 were classified as either benign or likely benign. Allele frequency of Rs799917 was high among Ethiopian, Ghanaian, and 1KG African subgroups. BRCA2: 13 BRCA2 SNPs were identified: Missense: rs766173, rs144848, rs1799944, rs169547; synonymous: rs1801439, rs1801499, rs1801406, rs543304, rs206075, rs1799955, rs9590940; downstream/missense: rs1801426; variant of 5'Prime UTR: rs1799943. Rs766173 caused a deleterious missense mutation, with conflicting interpretations of pathogenicity. No SNPs were previously reported pathogenic, 4 had uncertain significance, and 8 were either benign or likely benign. No SNPs had high allele frequency in African ancestry. Conclusions The BRCA-1 SNP Rs799917 has a high allele frequency rate among Ethiopian, Ghanaian, and 1KG African ancestry, suggesting this mutation is potentially unique to African ancestry. Further investigation with RNA seq or whole genome sequencing in larger cohorts is warranted. Citation Format: Solange Bayard, Rachel Martini, Yalei Chen, Brittany Jenkins, Isra Elhussin, Esther Cheng, Syed Hoda, Paula Ginter, Jeffrey Hanover, Rozina Zeidan, Joseph Oppong, Kofi Gyan, Clayton Yates, Rick Kittles, Engida Abebe, Ishmael Kyei, Frances Aitpillah, Michael Adinky, Lisa Newman, Melissa Davis. BRCA sequence variants in breast cancer patients with African ancestry [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-139.

Chemotherapy regimen choice and patient outcomes in early-stage triple-negative breast cancer: a retrospective analysis.

Background:Triple-negative breast cancer (TNBC) is associated with a poor prognosis when compared to hormone receptor–positive breast cancers. Anthracycline-based regimens (ABRs) are mainstay for treatment of non-metastatic TNBC. However, anthracyclines are associated with an increased risk of potentially life-threatening adverse effects. We sought to evaluate outcomes in patients with early TNBC treated with ABRs versus those treated with anthracycline-sparing regimens (ASRs).Methods:All patients treated for stage I–III TNBC who had undergone curative-intent surgery at a large academic medical center between January 2013 and May 2018 were included in this retrospective study. Event-free survival (EFS) and disease-free survival (DFS) were the primary endpoints, with overall survival (OS) as a secondary endpoint and were defined as per standardized STEEP criteria. Kaplan–Meier, multivariable Cox regression, and log-rank tests were used to define key survival and treatment-related differences between subjects treated with ABRs versus ASRs.Results:One hundred thirty-two patients met inclusion criteria with a median follow-up of 55.9 months. Twenty-seven patients (20%) had disease recurrence and 20 (15%) died. Patients in the ABR group were more likely to have nodal involvement (chi-square p = 0.011). Patients treated with ABRs (n = 26, 20%) compared with ASRs (n = 106, 80%) had significantly shorter median EFS (32.4 months vs not reached (NR), p < 0.001), DFS (26.2 months vs NR, p < 0.001), and OS (49.2 months vs NR, p < 0.001). The shorter survival observed in the ABR group persisted after adjusting for nodal status and on multivariate analysis. Of the 26 ABR-treated patients, 9 (35%) had an anthracycline added after suboptimal response to an ASR. Regardless of reason for anthracycline inclusion, the survival outcomes were similar. No cardiac or secondary leukemic events were observed in either group.Conclusion:ABRs were associated with shorter EFS, DFS, and OS, even after adjusting for certain high-risk clinical features.

Accelerating progress in early triple-negative breast cancer: A viewpoint on antibody-drug conjugates, back from St Gallen breast cancer conference 2021

Metastatic triple-negative breast cancer (mTNBC) is associated with an aggressive disease course, and limited treatment options. The recent accelerated drug development in the space of mTNBC has been driven by a precision-medicine approach, with the potential to deliver more personalized treatments and result in better outcomes. Antibody-drug conjugates (ADCs) have introduced a novel paradigm in the space of mTNBC, leading to the approval of the first targeted agent in this setting. The research and development of ADCs comes in parallel with the identification of tumor-specific targets of pharmacological interest. As a result, ADCs bring the potential for agnostic treatment delivery-across multiple histology types, and theranostically, by coupling tumor-antigen identification and treatment, as a continuum. In this perspective, recent progress in ADCs development for early and mTNBC are outlined, in the trade-off of patient selection, tumor specificity, precise drug delivery, potent payloads safety and quality of life.

Functional Mapping of AKT Signaling and Biomarkers of Response from the FAIRLANE Trial of Neoadjuvant Ipatasertib plus Paclitaxel for Triple-Negative Breast Cancer.

Despite extensive genomic and transcriptomic profiling, it remains unknown how signaling pathways are differentially activated and how tumors are differentially sensitized to certain perturbations. Here, we aim to characterize AKT signaling activity and its association with other genomic or IHC-based PI3K/AKT pathway biomarkers as well as the clinical activity of ipatasertib (AKT inhibitor) in the FAIRLANE trial. In FAIRLANE, 151 patients with early triple-negative breast cancer (TNBC) were randomized 1:1 to receive paclitaxel with ipatasertib or placebo for 12 weeks prior to surgery. Adding ipatasertib did not increase pathologic complete response rate and numerically improved overall response rate by MRI. We used reverse-phase protein microarrays (RPPA) to examine the total level and/or phosphorylation states of over 100 proteins in various signaling or cell processes including PI3K/AKT and mTOR signaling. One hundred and twenty-five baseline and 127 on-treatment samples were evaluable by RPPA, with 110 paired samples at both time points. Tumors with genomic/protein alterations in PIK3CA/AKT1/PTEN were associated with higher levels of AKT phosphorylation. In addition, phosphorylated AKT (pAKT) levels exhibited a significant association with enriched clinical benefit of ipatasertib, and identified patients who received benefit in the absence of PIK3CA/AKT1/PTEN alterations. Ipatasertib treatment led to a downregulation of AKT/mTORC1 signaling, which was more pronounced among the tumors with PIK3CA/AKT1/PTEN alterations or among the responders to the treatment. We showed that the high baseline pAKT levels are associated with the alterations of PI3K/AKT pathway components and enriched benefit of ipatasertib in TNBC.

Platinum and Taxane Based Adjuvant and Neoadjuvant Chemotherapy in Early Triple-Negative Breast Cancer: A Narrative Review.

Platinum (Pt) derivatives such as cisplatin and carboplatin are the class of drugs with proven activity against triple-negative breast cancer (TNBC). This is due to the ability of Pt compounds to interfere with the DNA repair mechanisms of the neoplastic cells. Taxanes have been efficacious against estrogen receptor-negative tumors and act by disruption of microtubule function. Due to their distinct mechanisms of action and routes of metabolism, the combination of the Pt agents and taxanes results in reduced systemic toxicity, which is ideal for treating TNBC. Also, the sensitivity of BRCA1-mutated cells to taxanes remains unsolved as in vitro evidence indicates resistance against taxanes due to BRCA1 mutations. Recent evidence suggests that the combination of carboplatin and paclitaxel resulted in better pathological complete response (pCR) in patients with TNBC, both in neoadjuvant and adjuvant settings. In vitro studies showed sequential dependency and optimal time scheduling of Pt- and taxane-based chemotherapy. Also, combining carboplatin with docetaxel in the NAC regimen yields an excellent pCR in patients with BRCA-associated and wild-type TNBC. TNBC is a therapeutic challenge that can be tackled by identifying new therapeutic sub-targets and specific cross-sections that can be benefitted from the addition of Pt- and taxane-based chemotherapy. This review summarizes the merits as well as the mechanism of Pt- and taxane-based adjuvant and neoadjuvant chemotherapies in early TNBC from the available and ongoing clinical studies.

Survival benefit of platinum-based regimen in early stage triple negative breast cancer: A meta-analysis of randomized controlled trials

Platinum (Pt)-based chemo-regimens have been proved effective in neoadjuvant and salvage chemotherapy of triple negative breast cancer (TNBC). However, the survival benefit of Pt-based regimens in early stage TNBC(eTNBC) treatment has remained unclear. We conducted a meta-analysis to explore its role in improving the clinical outcomes of eTNBC. We carried out a comprehensive literature search on 15 March 2021 for randomized controlled trials (RCTs) comparing ajuvant/neoadjuvant Pt-based and Pt-free chemo-regimens in eTNBC patients, according to PRISMA 2020. We extracted the survival data and utilized the STATA software to calculate the summarized hazard ratios (HRs) and 95% confidence interval (95% CI) for overall survival (OS) and disease-free survival (DFS). Seven eligible RCTs enrolling a total of 2,027 eTNBC patients were identified in this meta-analysis, with 1,007 receiving Pt-free regimens, and the other 1,020 patients receiving Pt-based regimens, respectively. Patients in Pt-based regimens arm were associated with significant improved DFS (HR = 0.70, 95% CI: 0.58–0.84), and OS (HR = 0.78, 95% CI: 0.61–1.00). The survival benefits of DFS remained consistent in both the two strategies of Pt usage, either adding Pt to standard anthracyclines&taxanes based regimens (A&T + Pt), or combination of Pt and taxanes alone (TPt). The survival benefits also remained consistent in either neoadjuvant or adjuvant use of Pt. The present meta-analysis of RCTs revealed that Pt-based chemo-regimens could significantly improve both DFS and OS for eTNBC patients. Based on efficiency and toxicity, we recommend Pt-based regimens for eTNBC, especially the “A&T + Pt” mode if the toxicities are tolerable, which may lead TNBC therapy into a new era.

Efficacy and Safety of Adding Immune Checkpoint Inhibitors to Neoadjuvant Chemotherapy Against Triple-Negative Breast Cancer: A Meta-Analysis of Randomized Controlled Trials.

BackgroundImmune checkpoint inhibitors (ICIs) have shown promising anti-tumor activity in multiple malignances including breast cancer. However, the responses can vary. This meta-analysis was conducted to evaluate the efficacy and safety profile of adding ICIs to neoadjuvant chemotherapy against triple-negative breast cancer (TNBC) and assess correlation of PD-L1 tumor status with responses.MethodsEligible studies were retrieved from the PubMed, Embase, and Web of Science databases. Randomized controlled trials (RCTs) that investigated ICI-containing versus ICI-free neoadjuvant therapy were included in this study. Meta-analyses were performed using Review Manager Version 5.2 software.ResultsThis study included four RCTs containing 1795 patients with early TNBC. Compared with ICI-free neoadjuvant therapy, ICI-containing neoadjuvant therapy significantly increased the pathological complete response (pCR) rates in TNBC (odds ratio [OR] = 2.14, 95% confidence interval [CI]: 1.37–3.35, P < 0.001). In subgroup analysis, the addition of ICI to neoadjuvant chemotherapy was significantly associated with increased pCR rate in both PD-L1-positive TNBC (OR = 1.79, 95% CI: 1.33–2.41, P < 0.001) and PD-L1-negative TNBC (OR = 1.84, 95% CI: 1.14–2.99, P = 0.01). Patients with TNBC receiving ICI-containing neoadjuvant therapy had a better event-free survival (hazard ratio = 0.66, 95% CI: 0.48–0.89, P = 0.007) than those who receiving ICI-free neoadjuvant therapy. A significantly higher risk of adverse events including adrenal insufficiency, increased aspartate aminotransferase, dry skin, hepatitis, hyperthyroidism, hypothyroidism, infusion related reaction, pyrexia, and stomatitis was associated with ICI-containing neoadjuvant therapy.ConclusionICI-containing neoadjuvant therapy significantly increased the pCR rate in TNBC patients, independently of PD-L1 status. The addition of ICI to neoadjuvant chemotherapy may be considered an option for TNBC patients.

Immune checkpoint inhibitors plus neoadjuvant chemotherapy in early triple-negative breast cancer: a systematic review and meta-analysis

PurposeSome studies have shown that Immune checkpoint inhibitors (ICIs) have a favorable efficacy in advanced triple negative breast cancer (TNBC) patients, but the results are controversial in neoadjuvant chemotherapy (NACT) stage. The purpose of this study is to evaluate the efficacy and safety after NACT plus ICIs in early TNBC patients.MethodsAfter searching PubMed, EMBASE, the Cochrane library and several mainly oncology conferences up to 30 January 2021 systematically, and define randomized controlled trials (RCTs) exploring the efficacy and safety of programmed death protein-1/programmed cell death-Ligand 1(PD-1/PD-L1) inhibitors plus neoadjuvant chemotherapy in TNBC patients. The primary endpoint was the pathological complete response (pCR) in intention-to-treat populations (ITT), and the secondary endpoints were event-free survival (EFS) and safety analysis in the ITT populations.ResultsSix RCTs (N = 2142) were included in our meta-analysis; NACT plus ICIs increased pCR rates compared with NACT in intention-to-treat (ITT) populations (OR: 1.91; 95% CI: 1.32–2.78, P < 0.001). The pCR rate also increased in both PD-L1 positive (OR: 1.65; 95% CI: 1.26–2.16, P < 0.001) and PD-L1 negative patients (OR: 1.56; 95% CI: 1.04–2.33, P = 0.03), especially in PD-L1 positive patients. The benefit was also observed in nodal-positive populations (OR: 2.52; 95% CI: 1.69–3.77, P < 0.001) and Eastern Cooperative Oncology Group performance-status score (ECOG PS) 0 subgroup (OR: 1.90; 95% CI: 1.42–2.53, P < 0.001). Three RCTs (N = 1615) reported EFS and the results showed that adding PD-1/PD-L1 inhibitors increased EFS (HR 0.65, 95% CI 0.50–0.83, P = 0.0007) in ITT populations with a short follow-up time. In the safety analysis of 2205 patients with early TNBC from five eligible studies, NACT plus ICIs had a higher risk of grade 3–4 diarrhea (OR: 2.54; 95% CI: 1.21–5.32; P = 0.01), any grade of adverse effects(AEs)including vomiting (OR: 1.37; 95% CI: 1.00–1.86; P = 0.05), hyperthyroidism (OR: 6.04; 95% CI: 2.39–15.29; P < 0.001), and hypothyroidism (OR: 5.04; 95% CI: 3.02–8.39; P < 0.001).ConclusionsPD-1/PD-L1 inhibitors combined with chemotherapy can improve pCR rates and EFS, and with an increased incidence of some immune-related AEs compared with chemotherapy alone. NACT plus ICIs might be an option in patients with in PD-L1 positive and high-risk populations with positive nodal disease early TNBC.