Drug resistance in breast cancer: Mechanisms and strategies for management.

Background: Breast cancer is currently the leading cause of cancer morbidity and mortality among Algerian women. To date, triple negative breast cancer (TNBC) shows substantial overlap with basal type cancer and it is associated with aggressive tumor behavior, poor prognosis and BRCA1 mutations. In the present study, we screened for the prevalence of BRCA1 and BRCA2 germline mutations in a cohort of 169 TNBC patients using PCR-Sanger sequencing and NGS with a cancer panel of 30 hereditary cancer genes or BRCA1/BRCA2 genetic test. Materials and Methods: 169 TNBC patients and their relatives were referred trough several public hospitals from six years (2013-2019). BRCA1 germline mutation was screened using PCR-Sanger sequencing in 66 TNBC patients with strong family history of breast and ovarian cancer and 103 sporadic TNBC patients including all exons where a mutation was previously found in Algerian population (exons 2, 3, 4, 10, 17 and 19). BRCA2 germline mutation was screened using PCR-Sanger sequencing in 24 TNBC patients with strong family history of breast cancer including all exons where a mutation was previously found in Algerian patients (exons 10 and 22). In addition, nine (9) TNBC patients with strong family history of breast and ovarian cancer were analyzed by NGS using BRCA1 and BRCA2 test or a cancer panel of 30 hereditary genes (Colors genomics). Results: The analysis of the genomic DNA samples of 169 TNBC patients revealed that 15 patients carried pathogenic germline variants in BRCA1 gene and three patients carried pathogenic variants in BRCA2 gene (10.65%). Eight distinct germline mutations in BRCA1 have been detected in this study: c.83_84delTG, c.181T>G, c.798_799delTT, c.505C>T, c.923_924delGC, c.2125_2126insA, c.5257A>G and deletion of exon 15. Interestingly, the recurrent and specific mutation c.83_84delTG has been detected in 4 unrelated TNBC patients. The pathogenic variant c.2125_2126insA has been detected in three unrelated families and also in the first relatives of 2 patients. The rare likely pathogenic variant BRCA1 c.5257A>G/p.Arg1753Gly has been detected in young female TNBC patient. The Del exon 15 in BRCA1 has been detected in two unrelated patients. Three distinct germline mutations in BRCA2 have been detected in three TNBC patients: c.1813dupA, c.7654dupA and c.8485C>T. Interestingly, these three mutations are reported for the first time in Algerian population. The c.1813dupA and c.8485C>T pathogenic variants have been detected in two young female TNBC patients with a family history of male breast cancer. Conclusions: In the current study, we detected recurrent germline mutations in BRCA1 gene in early onset TNBC patients. BRCA2 pathogenic variants have also been detected in young female TNBC patients. TNBC immunophenotype should be considered as an additional criterion for genetic counselling and testing of BRCA genes in Algerian women with early onset breast cancer. Citation Format: Farid Cherbal, Chiraz Mehemmai, Hadjer Gaceb, Hassen Mahfouf, Kada Boualga. BRCA1 and BRCA2 germline mutational spectrum in Algerian triple negative breast cancer (TNBC) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1451.

Background: triple-negative breast cancer (TNBC) is associated with hereditary and environmental risk factors plus an overall worse prognosis compared to other Breast Cancer (BC) subtypes. While TNBC risk factors, prevalence, clinical characteristics and prognosis may vary throughout different populations, limited data on Latin American patients forces clinical decisions to be based predominantly on data coming from non-Hispanic women. To obtain local epidemiological information, regarding risk factors and clinical outcomes, we analysed the largest Chilean BC registry. Methods: we conducted a retrospective population-cohort study involving females with any stage TNBC, treated at a community hospital (mid-low income) and at an academic private hospital (high income), between the years 2010 and 2021. Risk factors, reason for consultation, clinical and pathological characteristics and prognosis were separately analysed for both TNBC and non-TNBC subgroups. Univariate and multivariate analyses were performed to identify prognostic factors for survival on TNBC patients. Results: From 5,806 patients, 647 (11.2%) were identified as TNBC. Compared to non-TNBC patients, women were younger (median age 55.2 vs. 57.2, p=0.0001), with 15.8% of TNBC patients having been diagnosed before the age of 40 compared to 9.6% in non-TNBC (p= 0.0001). TNBC had a significantly lower screen-detected cancer rate (14.5% vs. 31.6% p= 0.0001) and worse stage at diagnosis. No differences were seen between patients seen at a community hospital and private centre, for both TNBC rate and stage. Other risk factors such as parity, age at first gestation, menarche, hormone therapy replacement and obesity showed no significant differences between TNBC and no-TNBC patients (table 1). With a median follow up of 57 months, 5-year overall survival (OS) and BC specific death were significantly shorter for TNBC compared to non-TNBC (76.4% vs 88.1% and 78.9% vs 91.2%, respectively; p=0.0001) (table 2). In the multivariate analysis, TN subtype (HR=2.3, p=0.0001), stage (HR=2.05 for stage II vs stage I, HR=7.04 for stage III vs. stage I, p=0.0001), lower income (HR= 1.64, p=0.0001), and non-screened detected BC (HR=1.32, p=0.03) were all associated with worse overall survival (table 3). Conclusion: This is the first study focusing on TNBC characteristics in Chilean BC patients and to our knowledge, the largest performed in a Latin American population. We identified a lower proportion of TNBC patients when compared with data reported from other LA groups and worldwide, a very low screen detected cancer rate and as expected significantly lower TNBC survival rate compared to non-TNBC women. While TNBC patients were younger compared to the non-TNBC group, this age difference was marginal compared to other reported studies. Community hospital patients (with mid-low income) were associated with lower survival rates for both all-cause mortality and BC specific survival, regardless of a similar stage distribution at diagnosis. Reflecting an underlying interaction between social and biological factors that needs to be addressed. Table 1. Patient characteristics: Triple-negative versus noN-triple negative breast cancer BMI: Body mass index; FH: Family history * Difference is statistically significant. Table 2. Survival comparison in triple-negative versus non-triple negative breast cancer * Difference is statistically significant. Table 3. Cox Regression Multivariate analysis * Difference is statistically significant. Citation Format: Benjamin Walbaum, FRANCISCO ACEVEDO, Catherine Bauerle, Mauricio Camus, Manuel Manzor, Raul Martinez, Paulina Veglia, Marisel Navarro, Constanza Guerra, Francisco Dominguez, Tomas Merino, Lidia Medina, CÉSAR SÁNCHEZ. Real-world data of clinical characteristics, risk factors and outcomes of Chilean triple-negative breast cancer patients [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 P3-03-19.

Akt-targeted therapy as a promising strategy to overcome drug resistance in breast cancer – A comprehensive review from chemotherapy to immunotherapy

Introduction: There is a critical need to develop biomarkers of response and resistance to adjuvant chemotherapy for TNBC. In preliminary studies, homologous recombination deficiency (HRD)-causing alterations have been reported in TNBC patients. HRD may impact response to standard chemotherapy as well as investigational therapies, such as PARP inhibitors and platinum agents. We report on the prognostic impact of two such markers in a large cohort of early stage TNBC patients who were uniformly treated with adjuvant doxorubicin (A) and cyclophosphamide (C). Aims: To investigate BRCA1 promoter methylation (PM) and HRD score as prognostic markers in TNBC patients treated with adjuvant AC on S9313. Methods: SWOG protocol S9313 accrued 3,125 women with early stage breast cancer to two alternative dose schedules of AC with no difference in outcomes between the two arms (J Clin Oncol 2007). We identified 425 (14%) patients with centrally determined TNBC status for whom tissue was available. BRCA1 PM (methylation specific PCR) and HRD score (composite of loss of heterozygosity, telomeric allelic imbalance and large-scale state transitions, Myriad Genetics Inc.) were performed on genomic DNA isolated from pre-treatment FFPE breast tumor tissue. HRD was classified as positive if there was either a deleterious tumor(t) BRCA1 or BRCA2 mutation and/or a pre-defined HRD score > 42. The markers were tested for prognostic effect on DFS and OS using a Cox regression model with adjustment for randomized treatment assignment. Results: For 425 TNBC patients median age was 45 years (range 22-74) and at a median follow up of 10.2 years there are 166 DFS and 129 OS events (5 year DFS and OS = 74% and 82%, respectively; 10-year DFS and OS = 66% and 73%). BRCA1 PM was determined in 82% (348/425) and was detected in 32% of patients. Presence of BRCA1 PM was suggestive of better DFS, but not statistically significant (HR=0.74; 95% CI 0.50-1.08, p=0.12). HRD results were determined in 91% (379/425) and 67% were HRD positive (27% with tBRCA mutation and 40% tBRCA negative but HRD score >42). HRD positive status was associated with a better DFS (HR = 0.69; 95% CI 0.49-0.96 (p=0.027)) and OS (HR= 0.67; 95% CI 0.47-0.97 (p=0.032)). High HRD score (≥42) in tBRCA negative patients (n=274) was also associated with better DFS (HR = 0.62; 95% CI 0.42-0.92). tBRCA status (positive versus negative) did not impact DFS (p = 0.78). Conclusions: Two thirds of TNBC patients receiving adjuvant AC chemotherapy had tumor HRD positivity. HRD was associated with better DFS and OS, perhaps due to high responses to AC. HRD status has the potential to be used as a selection criterion to identify TNBC patients who receive significant benefit from anthracycline chemotherapy, and may also be of value in selecting patients suitable for treatment with other DNA damaging agents like platinum salts/PARP-inhibitors. Citation Format: Priyanka Sharma, William Barlow, Andrew K. Godwin, Harsh Pathak, Kamilla Isakova, Anne R. Hartman, Kristen M. Timms, Hannah M. Linden, Debu Tripathy, Gabriel N. Hortobagyi, Daniel F. Hayes. Impact of homologous recombination deficiency (HRD) biomarkers on outcomes in triple-negative breast cancer (TNBC) patients treated with AC chemotherapy (SWOG S9313) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1776. doi:10.1158/1538-7445.AM2017-1776

PurposeBreast cancer is one of the most commonly diagnosed cancers in women. Five subtypes of breast cancer differ in their genetic expression profiles and carry different prognostic values, with no treatments available for some types, such as triple-negative, due to the absence of genetic signatures that could otherwise be targeted by molecular therapies. Although endocrine treatments are largely successful for estrogen receptor (ER)-positive cancers, a significant proportion of patients with metastatic tumors fail to respond and acquire resistance to therapy. FOXA1 overexpression mediates endocrine therapy resistance in ER-positive breast cancer, although the regulation of chemotherapy response by FOXA1 has not been addressed previously. FOXA1, together with EP300 and RUNX1, regulates the expression of E-cadherin, and is expressed in luminal, but absent in triple-negative and basal-like breast cancers. We have previously determined that EP300 regulates drug resistance and tumor initiation capabilities in breast cancer cells.MethodsHere we describe the generation of breast cancer cell models in which FOXA1 expression has been modulated either by expression of hairpins targeting FOXA1 mRNA or overexpression plasmids.ResultsUpon FOXA1 knockdown in luminal MCF-7 and T47D cells, we found an increase in doxorubicin and paclitaxel sensitivity as well as a decrease in anchorage independence. Conversely, upregulation of FOXA1 in basal-like MDA-MB-231 cells led to an increase in drug resistance and anchorage independence.ConclusionTogether, these data suggest that FOXA1 plays a role in making tumors more aggressive.

Introduction: Triple negative breast cancer (TNBC) is a particularly aggressive form of the disease whose incidence is disproportionate in obese African American and Latina women. TNBC is commonly associated with acute early onset, poor survival and acquired drug-resistance. Obesity, characterized by high levels of leptin, is frequently found among these ethnic groups. We hypothesize that intact leptin-Notch-Wnt signaling crosstalk affects the development of drug-resistance in TNBC. Objective: To determine whether leptin signaling induces Notch/Wnt pathway crosstalk, decreasing the effectiveness of cisplatin in TNBC cells. Materials & Methods: TNBC cells (MDA MB 231 and HCC1806) and ER+ MCF-7 (as control) were treated with pharmacological doses of leptin and agonists of the Notch and Wnt pathways JAG1-17 mer peptide and Wnt-1, respectively. In addition, the cells were challenged with the leptin receptor, Notch pathway, and Wnt pathway antagonists LPrA2, DAPT, and Wnt-1 respectively. The impact of these molecules on cisplatin anti-cancer effects was also determined. Activation of Wnt (total/pβ-catenin), expression of Notch (Notch 1-4 and JAG1/Dll-4 and targets: survivin/Hey2), cell proliferation and apoptosis were determined by Western blot and flow cytometry. β-catenin levels were also investigated by immunofluorescence. We also determined the impact of the inhibition of leptin signaling (via LPrA2) on the expression of Wnt and Notch in DMBA-induced breast cancer from DIO (diet-induced obese) mice. Results: We found that leptin increased the levels of β-catenin mainly in TNBC cells. Similarly, inhibition of leptin signaling decreased Wnt/Notch expression in DMBA/DIO-breast cancer. Interestingly, leptin increased expression of Notch and attenuated the detrimental effects of cisplatin on breast cancer cells. Wnt-1 affected Notch levels but its effects were less pronounced. Conclusions: Leptin is able to induce the Notch and Wnt signaling pathways in breast cancer. Cisplatin effects were attenuated by leptin in TNBC probably through its crosstalk with Wnt and Notch signaling pathways. These results are particularly relevant for TNBC and obese patients, and suggest that leptin inhibition could be useful in increasing the chemotherapeutic effectiveness in TBNC by disrupting leptin-Wnt-Notch crosstalk. [This work was supported in part by NIH/NCI1SC1CA138658-02; NIH/ARRA/3SC1CA138658-02S1 and the Georgia Cancer Coalition Distinguished Cancer Scholar Award (to RRGP); CREDO (MSCR) 2R25RR017694-06A1 (to L.S.C); NIH/NIGMS R25 GM058268 and NCRR 5P20RR11104 (to T.Z.M); and facilities and support services at MSM (NIH RR03034 and 1C06 RR18386)]. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 785. doi:1538-7445.AM2012-785

Diallyl disulfide and diallyl trisulfide in garlic as novel therapeutic agents to overcome drug resistance in breast cancer

Cisplatin–gemcitabine therapy in metastatic breast cancer: Improved outcome in triple negative breast cancer patients compared to non-triple negative patients

Introduction: TNBC is heterogeneous disease with several molecularly defined subtypes (Lehman et al), each of which may be predictive of response to chemotherapy. TNBC molecular subtypes are associated with varied pathological responses to neoadjuvant chemotherapy. However, subtype specific long-term outcomes for TNBC patients treated with uniform adjuvant chemotherapy are not known. Aims: To characterize long-term outcomes of TNBC molecular subtypes (TNBCtypes) in patients treated with adjuvant doxorubicin (A) and cyclophosphamide (C) on S9313 Methods: SWOG 9313 accrued 3,125 women with early stage breast cancer to two alternative dose schedules of AC with no difference in outcomes between the two arms (J Clin Oncol 2007). From this trial we identified 425 (14%) patients with centrally determined TNBC for whom tissue was available. Microarray profiling was performed on genomic RNA extracted from pre-treatment FFPE tissue. A 101-gene expression model which has shown to reproduce the classification provided by the original 2188-gene algorithm (Ring et al) was applied to the microarray profiling to generate the following TNBCtypes–Basal-Like 1 (BL1), Basal-Like 2 (BL2), Mesenchymal (M), mesenchymal stem–like (MSL), and luminal androgen receptor (LAR). Immunomodulatory +/- (IM) status was assigned independent of the subtypes. Sequencing of BRCA1/2 from tumor DNA was also performed. The subtypes were tested for prognostic effect on DFS and OS using Cox regression model with adjustment for nodal status. Results: For 425 TNBC patients, the median age was 45 years, 33% were node-positive and 10-year DFS and OS = 66.3% and 74.1%, respectively. A total of 381/424 (89.7%) cases could be classified into TNBCtypes with distribution as follows: BL1=24%, BL2=8%, M=24%, MSL=11%, LAR=9%, unclassified (UNL) =24%. No association between TNBCtypes and race or nodal status was noted. Compared to other subtypes LAR subtype was associated with older age at diagnosis (median age 53 vs 45, p<0.001). Overall 24% of samples were IM+ and 25% demonstrated deleterious tBRCA1/2 mutation. DFS, tBRCA1/2 mutation and IM+ status distribution across different subtypes are provided in the table. All subtypes except for LAR demonstrated a drop in hazard function for recurrence after 5 years. 5 year DFS (%)10 year DFS (%)DFS HR (95% CI), p valueDeleterious tBRCA1/2 mutationIM+ statusBL184.5%77.5%141%60%BL281.3%70.5%1.59 (0.81-3.13) p = 0.1816%12%M69.2%61.2%2.06 (1.25-3.40) p = 0.00528%0%MSL54.8%50.0%2.38 (1.33-4.28) p = 0.00418%7%LAR74.3%53.8%2.24 (1.22-4.14) p = 0.0112%8%UNL76.4%71.8%1.36 (0.80-2.33) p = 0.2620%30% Conclusions: In the presence of adjuvant AC, TNBC molecular subtypes have varied prognosis, with BL1 subtype demonstrating the best prognosis and MSL and LAR subtypes demonstrating the worst prognosis. LAR subtype is associated with older age at diagnosis and continued elevated hazard function for recurrence after year 5. tBRCA1/2 mutations are distributed across all subtypes with the highest prevalence in BL1 and M subtypes. IM+ status was infrequently noted in non-BL1 subtypes. These findings underscore TNBC heterogeneity and the need to account for this heterogeneity in prospective clinical trials. Citation Format: Sharma P, Barlow WB, Hout DR, Seitz RS, Bailey DB, Godwin AK, Pathak H, Timms KM, Solimeno C, Linden HM, Porter P, Tripathy D, Hortobagyi GN, Thompson A, Pusztai L, Hayes DF. Impact of molecular subtypes on long-term outcomes in triple-negative breast cancer (TNBC) patients treated with adjuvant AC chemotherapy on SWOG S9313 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-06.

Here, we investigated the possible predictive value of stromal caveolin-1 (Cav-1) as a candidate biomarker for clinical outcome in triple negative (TN) breast cancer patients. A cohort of 85 TN breast cancer patients was available, with the necessary annotation and nearly 12 years of follow-up data. Our primary outcome of interest in this study was overall survival. Interestingly, TN patients with high-levels of stromal Cav-1, had a good clinical outcome, with >50% of the patients remaining alive during the follow-up period. In contrast, the median survival for TN patients with moderate stromal Cav-1 staining was 33.5 months. Similarly, the median survival for TN patients with absent stromal Cav-1 staining was 25.7 months. A comparison of 5-year survival rates yields a similar pattern. TN patients with high stromal Cav-1 had a good 5-year survival rate, with 75.5% of the patients remaining alive. In contrast, TN patients with moderate or absent stromal Cav-1 levels had progressively worse 5-year survival rates, with 40% and 9.4% of the patients remaining alive. In contrast, in a parallel analysis, the levels of tumor epithelial Cav-1 had no prognostic significance. As such, the prognostic value of Cav-1 immunostaining in TN breast cancer patients is compartment-specific, and selective for an absence of Cav-1 staining in the stromal fibroblast compartment. A recursive-partitioning algorithm was used to assess which factors are most predictive of overall survival in TN breast cancer patients. In this analysis, we included tumor size, histologic grade, whether the patient received surgery, radiotherapy or chemotherapy, CK5/6, EGFR, p53 and Ki67 status, as well as the stromal Cav-1 score. This analysis indicated that stromal Cav-1 expression was the most important prognostic factor for overall survival in TN breast cancer. Virtually identical results were obtained with CK5/6 (+) and/or EGFR (+) TN breast cancer cases, demonstrating that a loss of stromal Cav-1 is also a strong prognostic factor for basal-like breast cancers. Our current findings may have important implications for the close monitoring and treatment stratification of TN and basal-like breast cancer patients.

Purpose: Based on clinical and molecular data, breast cancer is a heterogeneous disease. Breast cancers that have no expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) are defined as triple negative breast cancers (TNBCs); luminal cancers have different expressions of ER, PR and/or HER2. TNBCs are frequently linked with advanced disease, poor prognosis and occurrence in young African women, and about 15% of the cases are associated with germline BRCA1/2 mutations. Since radiotherapy is utilized as a principle treatment in the management of TNBC, we aimed to investigate the chromosomal instability and radiosensitivity of lymphocytes in TNBC patients compared to luminal breast cancer patients and healthy controls using the micronucleus (MN) assay. The effect of mutations in breast cancer susceptibility genes on chromosomal radiosensitivity was also evaluated.Methods: Chromosomal radiosensitivity was evaluated in the G0 (83 patients and 90 controls) and S/G2 (34 patients and 17 controls) phase of the cell cycle by exposing blood samples from all patients and controls to 2 and 4 Gy ionizing radiation (IR).Results: In the G0 MN assay, the combined cohort of all breast cancer, TNBC and luminal patients’ exhibit significantly elevated spontaneous MN values compared to controls indicating chromosomal instability. Chromosomal radiosensitivity is also significantly elevated in the combined cohort of all breast cancer patients compared to controls. The TNBC patients, however, do not exhibit enhanced chromosomal radiosensitivity. Similarly, in the S/G2 phase, 76% of TNBC patients do not show enhanced chromosomal radiosensitivity compared to the controls. In both the G0 and S/G2 phase, luminal breast cancer patients demonstrate a shift toward chromosomal radiosensitivity compared to TNBC patients and controls.Conclusions: The observations of the MN assay suggest increased chromosomal instability and chromosomal radiosensitivity in South African breast cancer patients. However, in TNBC patients, the irradiated MN values are not elevated. Our results suggest that the healthy lymphocytes in TNBC patients could handle higher doses of IR.

e12017 Background: Cancer antigen 15–3 (CA 15–3) and carcinoembryonic antigen (CEA), are often used in follow up care of breast cancer and provide important clues to the clinicians for disease progression in metastatic and recurrent breast cancer. Triple-negative breast cancers are frequently defined as a single group identifiable using routine clinical tests. They are negative for estrogen receptor (ER), progesterone receptor (PR), and the human epidermal growth factor receptor 2 (HER-2), the so-called triple-negative breast cancers. In this study we compared the tumor markers of triple negative breast cancer and non-triple negative patients. Methods: We retrospectively analyzed serum CEA and CA 15–3 levels of both triple negative and non-triple negative breast cancer patients at the time of first diagnosis and when they developed metastatic disease. Results: 544 consecutive nonmetastatic breast cancer patients presenting at Hacettepe University Institute of Oncology, Ankara, Turkey, with a median age of 49 were evaluated. 15.1% of the patients were triple negative breast cancer. At the time of diagnosis triple negative group had lower serum CEA (2.5 ± 5.9 vs 4.0 ±16.4 p = 0.35) and CA 15–3 (23.7 ± 14.6 vs 37.1 ± 117; p = 0.021) levels compared to non-triple negative group. In patients who developed metastasis during follow up; the CEA (3.2 ± 3.8 vs 29.6 ± 106.4 p = 0.022) and CA15–3 (46.9 ± 46.3 vs 203.2 ± 534 p = 0.008) levels were also significantly lower in triple negative breast cancer group compared to non-triple negative group.In non-triple negative breast cancer patients who developed metastasis, mean serum levels of CEA and CA15–3 significantly increased compared to baseline, whereas in triple negative group who developed metastasis CEA and CA 15–3 levels did not differ significantly. Conclusions: While being a good laboratory parameter in the follow-up of patients with breast cancer metastases, tumor markers may not show the increased tumor burden in the triple-negative breast cancer patients. No significant financial relationships to disclose.

Introduction: Triple-negative breast cancer (TNBC), an aggressive form of breast cancer (BC) that is associated with poor prognosis, accounts for 10-15% of all BCs. Chemotherapy remains the standard of care (SOC) for advanced disease, with limited clinical benefit. Oncology clinical trials (CTs) are globally recommended and encouraged as the preferred treatment (tx) option for any cancer patient (pt). ‘TrialJectory’ (TJ) is an artificial intelligence (AI)-based technology that matches pts to oncology CTs. Here, we identified distinct characteristics of TNBC pts who signed up to the TJ platform compared to non-TNBC pts. Methods: Using AI and an unsupervised natural language processing approach, the TJ platform clinically matches pts to CTs. Matching is achieved by pt response to an online dynamic questionnaire (www.trialjectory.com) that collects detailed clinical data including clinico-pathologic characteristics, tx history, general health, and comorbidities. Those are compared to the eligibility criteria of available CTs to yield a high-quality actionable matched-trial list. Results: Between 1/2020 and 12/2021, out of 9796 BC pts that signed up, 2688 were TNBC pts (27%). There was no significant difference in age at sign-up between TNBC and non-TNBC patients (median age of 57 years vs 58 years, respectively). Consistently with Non-hispanic black (NHB) race prevalence in the different molecular subtypes in the general US population, NHB race had higher signup rate in TNBC compared to non-TNBC (9.95% vs 5.76%, respectively). TNBC pts signed up at a later disease stage compared to non-TNBC pts (19% of TNBC reported having a stage 1 disease compared to 27% of non-TNBC pts, p< 0.001).A significantly higher percentage of pts with advanced/metastatic TNBC signed up to the TJ platform before starting tx compared to non-TNBC patients (34% vs 22%, respectively, p< 0.001). Furthermore, there was a significant difference in the willingness to travel any distance within the US for a matched clinical trial between TNBC and non-TNBC pts (39% vs 34%, respectively, p< 0.001). Conclusions: In this study, we found significant differences in the characteristics of TNBC vs non-TNBC pts that have signed up to the TJ platform. There was an up to 2-fold enrichment of TNBC on the TJ platform pts compared to their frequency in the general population. While previous studies do not show a difference in stage distribution between different subtypes, TNBC patients initiated their search for CTs at a higher stage. In addition, advanced TNBC patients started their search earlier in their journey, before starting chemotherapy. This may reflect the lack of effective SOC and possibly, the motivation to avoid the use of chemotherapy. This is also supported by the willingness of TNBC patients to travel farther in order to identify and enroll in a CT compared to non-TNBC pts. Importantly, the motivation of TNBC pts to travel any distance has not been reduced despite the COVID-19 pandemic, reflecting a strong drive of this pt population to enroll in CTs. It also demonstrates that with the right access, diverse patient populations are willing to participate in clinical trials. In sum, TNBC pts are more likely to explore CT options, in the advanced stage setting, earlier in their journey. This study demonstrates the power of TJ platform for clinico-pathologic characterization and diverse pt groups, including their drivers and behavioral choices during their battle with cancer. Citation Format: Michal Safran, Yelena Lapidot, Tzvia Bader, Avital Gaziel. Triple Negative Breast Cancer (TNBC) patients are more likely to digitally explore clinical trial options and prior to receiving treatment for advanced disease compared to non-TNBC patients [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 P2-13-05.

Background: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype that affects about 20% of breast cancer patients and has a high incidence in young African American women. Currently the only therapeutic options for TNBC patients is chemotherapy, however, more than 60% of TNBC patients are highly resistant to chemotherapeutic treatment. The development of novel therapeutic approaches is essential to enable treatment of patients with chemo-resistant TNBC. Our lab focuses on the development of receptor-targeted theranostic nanoparticles. We have developed a class of urokinase plasminogen activator receptor (uPAR) targeted theranostic magnetic iron oxide nanoparticles (IONPs) carrying therapeutic agents that are clinically beneficial to TNBC patients, including DNA damaging agents, such as doxorubicin (Dox) or cisplatin (Cis). We are targeting uPAR because it is highly expressed in malignant cancers including aggressive breast cancer tissues and tumor stromal cells that are enriched in TNBC tissues. Methods: Tumor fragments from TNBC patients, obtained from a Phase II clinical trial that is ongoing at the Breast Cancer Clinic in the Winship Cancer Institute, were implanted in the mammary fat pad of SCID mice. The tumor xenografts grew to about 1 cm in diameter in 12 to 15 weeks. Tumor fragments were then implanted into the mammary fat pad and passaged through nude mice for testing the therapeutic efficacy of the uPAR-targeted nanoparticle-drugs. Histological analysis of post-chemotherapy TNBC and primary tumor xenograft tissues with or without uPAR-targeted IONP-Dox was conducted using immunohistochemistry and dual immunofluorescence techniques. Results: We have previously reported that the uPAR-targeted IONP-Dox causes tumor growth inhibition following systemic delivery. Using CD44 and uPAR as biomarkers we also reported histological analysis of post-chemotherapy TNBC and primary tumor xenograft tissues showed high levels of CD44+/CD24- tumor cells and up-regulation of uPAR. Primary TNBC xenografts treated with conventional Dox had increased levels of CD44+/CD24- cells and strong uPAR expression. Conversely, the tumor tissues from the uPAR-targeted IONP-Dox treated group showed decreased levels of CD44+/CD24- and uPAR positive cells. We have further investigated the biomarkers insulin-like growth factor 1 receptor (IGF-1R) and Ki67. IGF-1R has been shown to be overexpressed in more than 50% of TNBCs and may be associated with the drug-resistant TNBC phenotype, while Ki67 is a conventional biomarker for proliferation. We observed that uPAR-targeted IONP- Dox treatment decreased IGF-1R expression compared to the control group and the group treated with conventional Dox. We also observed that Ki67 expression was decreased in the uPAR-targeted IONP- Dox treatment group compared to control group and the group treated with conventional Dox. Conclusions: Results of our study demonstrated that uPAR-targeted theranostic IONPs selectively delivers therapeutic payloads of the chemotherapeutic drug Dox to inhibit the growth of uPAR positive tumor cells. It is likely that uPAR expressing tumor cells are an aggressive and potentially drug resistant cell population that overexpress breast cancer stem-like cell biomarker (CD44+/CD24-) as well as up-regulation of a growth factor receptor, IGF-1R. These results support further investigation of theranostic nanoparticles as an approach to overcome drug resistance in TNBC. Citation Format: Jasmine M. Miller-Kleinhenz, Hongyu Zhou, Weiping Qian, Ruth O'Regan, Amelia Zelnak, Toncred Styblo, Lily Yang. uPAR-targeted theranostic nanoparticles effectively decrease expression of IGF-1R and Ki67 in drug-resistant triple-negative breast cancer human xenograft. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B045.

Background: The optimal time between surgery and initiation of adjuvant chemotherapy is unknown, though delayed time to chemotherapy (TTC) is associated with decreased outcomes of breast cancer patients. Recently, studies have suggested that the association might be subtype-dependent and that TTC within 30 days should be warranted particularly in high-risk triple-negative breast cancer (TNBC) patients. Objective: To determine the extent to which TTC beyond 30 days is associated with reduced overall survival (OS) in TNBC patients. Methods: Using the population-based nationwide Netherlands Cancer Registry we identified TNBC patients diagnosed between 2006 and 2014 who received adjuvant chemotherapy. We distinguished between patients who underwent breast-conserving surgery (BCS) versus mastectomy given the difference in preoperative characteristics and outcomes. Median (95% confidence interval) follow-up was 82.9 (80.5-86.5) and 81.4 (79.5-83.9) months, respectively. Main outcomes and measures: The association between TTC beyond 30 days and OS was estimated with hazard ratios (HR) using propensity-score matched Cox proportional hazard analyses separately for patients who underwent BCS and mastectomy. Results: In total, 3016 patients were included, of whom 1079 (35.8%) underwent BCS and 1937 (64.2%) underwent a mastectomy. In matched patients who underwent BCS, 10-year OS was significantly better for patients with TTC within 30 days compared to patients with TTC beyond 30 days (84.4% vs. 76.9%, P=0.001). Patients with TTC beyond 30 days were more likely than those with TTC within 30 days to die within 10 years after surgery (HR 1.69 (95% CI 1.22-2.34), P=0.002). In matched patients who underwent mastectomy, there was no difference in 10-year OS between those with TTC within or beyond 30 days (74.5% vs. 74.7%, P=0.716), nor an increased risk of death for those with TTC beyond 30 days (HR 1.04 (95%-CI 0.84-1.28), P=0.716). In both populations, the associations were independent of adjuvant radiotherapy. Conclusions: The current results suggest that initiation of chemotherapy beyond 30 days is associated with decreased OS in TNBC patients who underwent BCS; no association was observed for patients who underwent a mastectomy. Therefore, timelier initiation of chemotherapy in TNBC patients undergoing BCS seems warranted. Citation Format: Erik Heeg, Perla J. Marang-van de Mheen, Marissa C. Van Maaren, Kay Schreuder, Rob A.E.M. Tollenaar, Sabine Siesling, Monique E.M.M. Bos, Marie-Jeanne T.F.D. Vrancken Peeters. Association between initiation of adjuvant chemotherapy beyond 30 days following surgery and overall survival among patients with triple-negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-07.