Chemotherapy For Breast Cancer Research Articles

Emulation and evaluation of tumor cell combined chemotherapy in isotropic/anisotropic collagen fiber microenvironments.

The rapid emergence of anisotropic collagen fibers in the tissue microenvironment is a critical transition point in late-stage breast cancer. Specifically, the fiber orientation facilitates the likelihood of high-speed tumor cell invasion and metastasis, which pose lethal threats to patients. Thus, based on this transition point, one key issue is how to determine and evaluate efficient combination chemotherapy treatments in late-stage cancer. In this study, we designed a collagen microarray chip containing 241 high-throughput microchambers with embedded metastatic breast cancer cell MDA-MB-231-RFP. By utilizing collagen's unique structure and hydromechanical properties, the chip constructed three-dimensional isotropic and anisotropic collagen fiber structures to emulate the tumor cell microenvironment at early and late stages. We injected different chemotherapeutic drugs into its four channels and obtained composite biochemical concentration profiles. Our results demonstrate that anisotropic collagen fibers promote cell proliferation and migration more than isotropic collagen fibers, suggesting that the geometric arrangement of fibers plays an important role in regulating cell behavior. Moreover, the presence of anisotropic collagen fibers may be a potential factor leading to the poor efficacy of combined chemotherapy in late-stage breast cancer. We investigated the efficacy of various chemotherapy drugs using cell proliferation inhibitors paclitaxel and gemcitabine and tumor cell migration inhibitors 7rh and PP2. To ensure the validity of our findings, we followed a systematic approach that involved testing the inhibitory effects of these drugs. According to our results, the drug combinations' effectiveness could be ordered as follows: paclitaxel + gemcitabine > gemcitabine + 7rh > PP2 + paclitaxel > 7rh + PP2. This study shows that the biomimetic chip system not only facilitates the creation of a realistic in vitro model for examining the cell migration mechanism in late-stage breast cancer but also has the potential to function as an effective tool for future chemotherapy assessment and personalized medicine.

Predictive analysis of breast cancer response to neoadjuvant chemotherapy through plasma metabolomics.

Preoperative chemotherapy is a critical component of breast cancer management, yet its effectiveness is not uniform. Moreover, the adverse effects associated with chemotherapy necessitate the identification of a patient subgroup that would derive the maximum benefit from this treatment. This study aimed to establish a method for predicting the response to neoadjuvant chemotherapy in breast cancer patients utilizing a metabolomic approach. Plasma samples were obtained from 87 breast cancer patients undergoing neoadjuvant chemotherapy at our facility, collected both before the commencement of the treatment and before the second treatment cycle. Metabolite analysis was conducted using capillary electrophoresis-mass spectrometry (CE-MS) and liquid chromatography-mass spectrometry (LC-MS). We performed comparative profiling of metabolite concentrations by assessing the metabolite profiles of patients who achieved a pathological complete response (pCR) against those who did not, both in initial and subsequent treatment cycles. Significant variances were observed in the metabolite profiles between pCR and non-pCR cases, both at the onset of preoperative chemotherapy and before the second cycle. Noteworthy distinctions were also evident between the metabolite profiles from the initial and the second neoadjuvant chemotherapy courses. Furthermore, metabolite profiles exhibited variations associated with intrinsic subtypes at all assessed time points. The application of plasma metabolomics, utilizing CE-MS and LC-MS, may serve as a tool for predicting the efficacy of neoadjuvant chemotherapy in breast cancer in the future after all necessary validations have been completed.

Longitudinal ultrasound-based AI model predicts axillary lymph node response to neoadjuvant chemotherapy in breast cancer: a multicenter study.

Developing a deep learning radiomics model from longitudinal breast ultrasound and sonographer's axillary ultrasound diagnosis for predicting axillary lymph node (ALN) response to neoadjuvant chemotherapy (NAC) in breast cancer. Breast cancer patients undergoing NAC followed by surgery were recruited from three centers between November 2016 and December 2022. We collected ultrasound images for extracting tumor-derived radiomics and deep learning features, selecting quantitative features through various methods. Two machine learning models based on random forest were developed using pre-NAC and post-NAC features. A support vector machine integrated these data into a fusion model, evaluated via the area under the curve (AUC), decision curve analysis, and calibration curves. We compared the fusion model's performance against sonographer's diagnosis from pre-NAC and post-NAC axillary ultrasonography, referencing histological outcomes from sentinel lymph node biopsy or axillary lymph node dissection. In the validation cohort, the fusion model outperformed both pre-NAC (AUC: 0.899 vs. 0.786, p < 0.001) and post-NAC models (AUC: 0.899 vs. 0.853, p = 0.014), as well as the sonographer's diagnosis of ALN status on pre-NAC and post-NAC axillary ultrasonography (AUC: 0.899 vs. 0.719, p < 0.001). Decision curve analysis revealed patient benefits from the fusion model across threshold probabilities from 0.02 to 0.98. The model also enhanced sonographer's diagnostic ability, increasing accuracy from 71.9% to 79.2%. The deep learning radiomics model accurately predicted the ALN response to NAC in breast cancer. Furthermore, the model will assist sonographers to improve their diagnostic ability on ALN status before surgery. Our AI model based on pre- and post-neoadjuvant chemotherapy ultrasound can accurately predict axillary lymph node metastasis and assist sonographer's axillary diagnosis. Axillary lymph node metastasis status affects the choice of surgical treatment, and currently relies on subjective ultrasound. Our AI model outperformed sonographer's visual diagnosis on axillary ultrasound. Our deep learning radiomics model can improve sonographers' diagnosis and might assist in surgical decision-making.

Cognitive impairment following breast cancer treatments: an umbrella review.

Cancer-related cognitive impairment (CRCI) refers to a cognitive decline associated with cancer or its treatments. While research into CRCI is expanding, evidence remains scattered due to differences in study designs, methodologies, and definitions. The present umbrella review aims to provide a comprehensive overview of the current evidence regarding the impact of different breast cancer therapies on cognitive functioning, with a particular focus on the interplay among objective cognitive deficits (ie, measured with standardized tests), subjective cognitive concerns, (ie, self-reported), and other mediating psycho-physical factors. The search was made in Pubmed, Embase, and Scopus for articles published until July 2023, following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis protocol. Chemotherapy and endocrine therapy appear consistently associated with CRCI in patients with breast cancer, primarily affecting memory, attention/concentration, executive functioning, and processing speed. Subjective cognitive concerns were often found weakly or not associated with neuropsychological test results, while overall CRCI seemed consistently associated with psychological distress, fatigue, sleep quality, and inflammatory and biological factors. Current evidence suggests that CRCI is common after chemotherapy and endocrine therapy for breast cancer. However, heterogeneity in study designs and the scarcity of studies on more recent treatments such as targeted therapies and immunotherapies, highlight the need for more systematic and harmonized studies, possibly taking into account the complex and multifactorial etiology of CRCI. This may provide valuable insights into CRCI's underlying mechanisms and potential new ways to treat it.

Long-term prospective outcome data using EndoPredict as risk stratification and chemotherapy decision biomarker in hormone receptor-positive, HER2-negative early breast cancer

Abstract Purpose To report the prospective long-term outcome data of patients whose chemotherapy decision was guided by the EndoPredict test. Methods Patients with hormone receptor-positive HER2-negative early breast cancer with 0–3 positive lymph nodes were enrolled. The EndoPredict test was carried out on all tumor samples. Treatment compliance, local recurrence, distant metastases, and survival were evaluated. Associations of EPclin risk stratification with 5-year disease-free survival and distant metastasis-free survival were evaluated by time-to-event analysis. Results 368 consecutive patients were included in the analysis. Median follow-up was 8.2 years. EndoPredict allocated 238 (65%) in the low-risk and 130 (35%) patients in the high-risk group. Risk for disease recurrence or death in EPclin high-risk patients was twofold higher than in EPclin low-risk patients (hazard ratio [HR] 2.08; 95% CI 1.26–3.44; p = 0.004). EPclin low-risk patients had a 5-year disease-free survival of 95.3% (95% CI 92.6–98.0%). EPclin high-risk patients were at higher risk of developing distant metastases or death (HR 2.21; 95% CI 1.27–3.88; p = 0.005). EPclin high-risk patients who underwent chemotherapy had a 5-year DFS of 89.1% (95% CI 82.7–96.1%) in contrast to high-risk patients without chemotherapy (68.9%; 95% CI 56.2–84.5%; HR 0.46; 95% CI 0.23–0.95; p = 0.036). EPclin high-risk patients were at higher risk of experiencing distant metastases or death than EPclin low-risk patients regardless of menopausal status (premenopausal: HR 3.55; 95% CI 1.17–12.32; p = 0.025; postmenopausal: HR 1.92; 95% CI 0.99–3.7; p = 0.054). Conclusion EndoPredict can guide decisions on adjuvant chemotherapy in early luminal breast cancer. EndoPredict risk stratification is also applicable in premenopausal women.

Factors Associated With Additional Axillary Disease in Patients With Positive Sentinel Lymph Nodes After Neoadjuvant Chemotherapy for Breast Cancer.

Background: In previous studies, breast cancer patients with positive sentinel lymph node(s) (SLN) after neoadjuvant chemotherapy (NAC) frequently had additional nonSLN involvement. Per guidelines, residual SLN disease warrants completion axillary lymph node dissection (cALND), which has increased morbidity. Given recent improvements in NAC, we hypothesized that nonSLN positivity may be lower than previously reported for certain subgroups.Methods: We retrospectively reviewed breast cancer patients who received NAC and had positive lymph nodes on SLN biopsy or targeted axillary dissection and underwent cALND at one institution in 1/2018-8/2023. Associations between nonSLN positivity and clinicopathologic factors were assessed with Fisher's exact test and multivariable logistic regression.Results: There were 122 female patients. Median age was 48years. Initially, 15 patients (12.3%) were cN0 and 107 patients (87.7%) were cN1. Largest SLN deposit was macrometastasis in 96 patients (78.7%), micrometastasis in 23 patients (18.9%), and isolated tumor cells in 3 patients (2.5%). Overall, 53 patients (43.4%) had nonSLN involvement. NonSLN positivity was higher in patients with cN1, ER+ HER2-, ypT2-3, SLN macrometastasis, and multiple positive SLN. On multivariable analysis, cN1 and ER+ HER2- remained associated with nonSLN positivity.Discussion: Among patients with positive SLN after NAC, clinically node positive and ER+ HER2- patients were more likely to have nonSLN involvement. Our findings support guidelines to consider omitting cALND in clinically node negative patients. With improving NAC, optimal axillary sampling, and radiation, omitting cALND may be safe in some clinically node positive triple negative or HER2+ patients with low volume residual disease, but further research is needed.

Abstract PO2-12-12: REaCT 5G: A randomized study comparing bone pain after 5 days of filgrastim or one day of pegfilgrastim for primary febrile neutropenia prophylaxis during neo-/adjuvant chemotherapy for early breast cancer

Abstract Background: Granulocyte colony stimulating factor (G-CSF) such as filgrastim (FIL) or pegfilgrastim (PEG) significantly reduces the risk of febrile neutropenia (FN) and treatment-related hospitalization in patients with early breast cancer receiving chemotherapy. However, patients receiving G-CSF can experience clinically significant bone pain. Previous studies examining post-GCSF bone pain were mostly based on physician pain assessment and compared mixed doses (30/60/100 μg/kg) of PEG vs. FIL (5μg/kg/day or 300 μg/day) given for 7 to 14 days. Based on a randomized non-inferiority study, 5 days of FIL is considered non-inferior to 10 days of FIL to prevent FN and hospitalizations and is frequently used in patients receiving chemotherapy for breast cancer. Patient-reported bone pain after 5 days of FIL vs. single dose of PEG has never been compared in a prospective randomized study and has important implications for patient and physician treatment preferences. Methods: In this multicenter, open-label trial, patients receiving neo-/adjuvant chemotherapy for early-stage breast cancer requiring primary FN prophylaxis with G-CSF were randomized 1:1 to either 5 days of FIL (300 μg or 480μg if ≥ 90 kg) or 1 day of PEG (6 mg) with each cycle of chemotherapy. The primary endpoint was bone pain using area under the curve (AUC) of the daily pain score from days 1-5 (AUC score 0 to 40) during cycle 1. We used linear regression adjusting for stratification factors [cancer center (2 centers) and chemotherapy regimen (taxane (TAX) or anthracycline (ANTH)-based during cycle 1] and prespecified baseline covariates: age, pain, and use of pain medications pre-chemotherapy. Supportive analysis of bone pain across cycles 1 to 4 was conducted using repeated linear regression. Key secondary endpoints included incidence of FN, hospitalizations, chemotherapy delay, dose-reduction or discontinuation, and chemotherapy-related deaths. Results: From June 2021 to March 2023, 233 patients were enrolled, with 217 patients (108 FIL/109 PEG) in the intention-to-treat analysis; 16 (7.4%) patients were excluded because of incomplete follow-up. Participants were mean age 55.6 years; almost exclusively female (99.1%), on chemotherapy regimen TAX 57% vs. ANTH 43%, had mean baseline pain score 1.12, and prevalence of pain medication use pre-chemotherapy was acetaminophen 14.7%, non-steroidal anti-inflammatory drugs (NSAIDs) 6.0% and opioids 3.2%. Characteristics were balanced between arms (Table 1). After repeated measures linear regression adjusted for age, chemotherapy regimen, baseline pain, and use of pain medications pre-chemotherapy, mean AUC for bone pain at cycle 1 was 10.94 for FIL and 10.12 for PEG (mean difference 0.82; 95% CI: -1.59, 3.23; p = 0.516). There was no significant difference between arms across treatment cycles (interaction p = 0.785; mean time-averaged difference 0.28; 95% CI: -1.75, 2.32). Across cycles 1 to 4, mean peak pain over 5 days post-GCSF was 3.27 vs. 3.41 (p=0.700); frequency of bone pain during first 8 days (pain score &amp;gt; 0) was 52.5% vs. 51.3%; p=0.358, and mean frequency of severe pain (pain score ≥ 5) was 17.5% vs. 15.2%; p=0.014 for FIL vs. PEG, respectively. The incidence of FN [4.6% vs. 0%, absolute difference 4.6% (95% CI: -0.3%, 9.5%; p=0.069)] and hospitalization [FN and non-FN related: 10.2% vs. 1.8%, absolute difference of 8.4% (95% CI: 1.2%, 15.5%; p=0.021)] was higher in the FIL group. There were no significant differences in chemotherapy delay (13% vs. 11%; p=0.815), dose reduction (14.8% vs. 14.7%; p=0.999), early discontinuation (8.3% vs. 5.5%; p=0.580), or chemotherapy-related death (0.9% vs. 0%; p=0.996) in the FIL vs. PEG groups, respectively. Conclusion: There was no difference in patient-reported bone pain after 5 days of FIL or PEG, even after controlling for important clinical factors. Importantly, the study observed higher rates of FN and hospitalizations in patients receiving FIL for 5 days only. Table 1 Baseline Characteristics Citation Format: Terry Ng, Yuxin Zhang, Carol Stober, Jennifer Shamess, Natalie Mills, Stuart Nicholls, Mohammed Ibrahim, Daniel Davoudpour, Christopher Armiento, Marie-France Savard, Moira Rushton, Arif Awan, Sandeep Sehdev, John Hilton, Xinni Song, Rakesh Goel, Fiona Macdonald, Kelly Daigle, Lisa Vandermeer, Monica Taljaard, Mark Clemons. REaCT 5G: A randomized study comparing bone pain after 5 days of filgrastim or one day of pegfilgrastim for primary febrile neutropenia prophylaxis during neo-/adjuvant chemotherapy for early 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 PO2-12-12.

Abstract PS05-02: PET Imaging of PARP Expression as a Biomarker of Response to Chemotherapy in Breast Cancer: A Nonrandomized Clinical Trial

Abstract Introduction: Poly–(adenosine diphosphate–ribose) polymerase (PARP) proteins are involved in double-stranded break repair, mediated through homologous recombination (HR) and non-homologous end joining (NHEJ). The majority of PARP activity in this context is attributed to PARP-1 (85-90%). PARP-1 binding to damaged DNA, catalytic activity, and subsequent release to allow access for other DNA repair proteins are necessary for efficient DNA repair. The critical function of PARP-1 in these processes makes this protein a unique potential biomarker of DNA repair capability. [18F]FluorThanatrace ([18F]FTT) is an 18F-labeled PARP inhibitor analog that binds to the same site as approved PARPi drugs. We hypothesized that the biologically relevant form of PARP in untreated breast cancer might provide an indication of functional tumor DNA repair capabilities and therefore predict chemotherapy response. Thus, this study aimed to determine whether a non-invasive quantitative measure of in vivo PARP expression correlated with response to chemotherapy in breast cancer. Methods: A single-arm prospective trial enriched for subjects with triple negative breast cancer (TNBC) was conducted at the University of Pennsylvania from May 2017 to March 2022 (NCT03083288 and NCT03846167). Inclusion criteria were primary breast cancer with tumor diameter of at least 1 cm on conventional imaging and willingness to undergo an [18F]FTT-PET scan prior to neoadjuvant chemotherapy. Participants provided written informed consent. [18F]FTT uptake in breast cancer was measured pre-therapy and tested for association with pathologic complete response (pCR). Subjects were scanned on an Ingenuity TF PET/CT (Philips Healthcare) following injection of [18F]FTT using a 20-minute static acquisition. Peak 1 cm3 average uptake (SUVpeak) were recorded from a spherical region-of-interest (ROI) covering the primary malignancy, guided by CT and prior imaging studies. All SUVs were partial volume corrected and normalized using muscle (NM). A Mann-Whitney test was used to determine if [18F]FTT uptake differed by pCR. Receiver operating characteristic (ROC) curves were constructed to test the performance of [18F]FTT uptake in predicting pCR. Statistical analyses utilized STATA v15.1 with significance based on a two-sided alpha level of ≤0.05. Participants: Twenty-six women with stage I-III breast cancer met inclusion criteria with age range of 29-74 years and self-reported race as Asian (1, 4%), Black (9, 37%) or White (16, 60%). One subject had bilateral tumors (ER+ stage IIA and HER2+ stage I) that were evaluated separately (27 total tumors). Breast tumors were pathologically confirmed and included 6 (22%) ER+/HER2-, 5 (19%) HER2+, and 16 (59%) TNBC. Germline sequencing was available for 21 participants. Results: Mean tumor diameter ranged from 15 to 91 mm (median 30 mm). A considerable range of [18F]FTT uptake was seen across subjects (SUVpeak/NM 0.66-6.5). [18F]FTT uptake was independent of subtype (ER+, HER2+, TN) (P=0.35), stage (P=0.39), and between mutations in genes associated with homologous recombination deficiency (i.e., BRCA1/2, PALB2) and wild-type (P=0.73). In the TNBC cohort, pre-treatment [18F]FTT uptake was higher in subjects who went on to have a pCR (n=16, P=0.05), while a trend toward higher uptake was seen when including all tumor types (n=27, P=0.11). ROC analysis of the value of [18F]FTT uptake for predicting pCR revealed an AUC of 0.79 and showed that a threshold SUV ratio &amp;lt; 2.47 predicted pCR in TNBC patients with a 100% specificity and 64% sensitivity. Conclusions: These early clinical results suggest a relationship between [18F]FTT uptake, a measure of PARP expression, and chemotherapy sensitivity in TNBC, warranting future studies to elucidate underlying mechanistic processes and potential clinical implications. Citation Format: Sarah Gitto, Anthony Young, Ira Bleiweiss, Amy Clark, Elizabeth McDonald. PET Imaging of PARP Expression as a Biomarker of Response to Chemotherapy in Breast Cancer: A Nonrandomized Clinical 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 PS05-02.

Abstract PO4-02-11: Optimizing Taxane-based Chemotherapy in Breast Cancer: Retrospective study comparing 4 cycles of TC to 6 cycles of TC

Abstract Breast cancer remains one of the most prevalent cancers among women worldwide. First-line chemotherapy options include anthracycline (AC-T) and Taxane (TC) based regimens. While anthracycline-based chemotherapy is most commonly used, the use of anthracycline-sparing regimens is also approved. The US Oncology 9735 trial conducted in the mid 2000s showed that four cycles of docetaxel and cyclophosphamide (TC4) were superior to four cycles of Doxorubicin and cyclophosphamide (AC). The follow-up ABC trials compared six cycles of TC(TC6) to AC-T. This trial showed that while AC-T was superior to TC, the difference was modest. AC-T has remained the standard of care, but TC is an acceptable option. One retrospective analysis involving 143 patients showed TC4 was non-inferior to TC6, and suggested that TC4 had fewer adverse events; however, statistical significance was not reached. The question remains whether six cycles of TC is required, or if four cycles is adequate. Methods: Patient information was retrieved from the EMR of a large private oncology group. The EMR was screened for all breast cancer patients who began treatment with TC between 1/1/2011 and 12/31/2021. Patients were required to have continuous follow-up, documented up to at least 6/30/2022. Only patients receiving TC as the first-line setting were included, while patients with metastatic disease were excluded. Adjusted Kaplan Meier curves for overall survival (OS) and disease-free survival (DFS) were generated. A log-rank test was used to determine the statistical difference between the two curves. OS was defined from the date of the last chemotherapy given to death. DFS is defined from the date of the last chemotherapy given to disease recurrence. The Chi-square analysis test of homogeneity was conducted to evaluate the differences in reported symptoms. Statistical analysis was completed with IBM SPSS version 29. Ethical approval was obtained from The Brooklyn Hospital Center Institutional Review Board. Results: A total of 376 charts were reviewed, out of which 224 met the criteria for inclusion. Of these 191 patients received TC4 and 33 received TC6. TC4 patients were noted to be older than TC6 patients. There were a higher percentage of hormone-positive cancers in the TC4 group while the TC6 group had a larger proportion of triple-negative breast cancers. There was a larger proportion of stage III patients that received TC6 than in TC4. TC6 patients were also noted to receive neo-adjuvant chemotherapy at a substantially higher rate. A greater proportion of patients in the TC4 group received breast-conserving surgery, with radiation than the TC6 group. TC6 had a completion rate of 76 % (Table 1). There was a significant difference in DFS noted between TC4 and TC6 (p = 0.016) with TC6 patients having a higher rate of relapse. No difference was noted in the overall survival. No differences were seen in side effects between TC4 and TC6, however, there was a trend toward high rates of neutropenia, anemia, and neuropathy seen in the TC6 group (Table 2). Conclusions: This real-world retrospective study reviewed patients who received TC in a large community oncology practice. The study reaffirms conclusions seen in previous retrospective studies conducted in the academic setting that there is no difference in overall survival when using six cycles of TC compared to four cycles of TC. Slight detriment was seen in the DFS setting when using TC6 however the small sample size along with the larger proportion of patients with stage III disease make it challenging to interpret this finding. There was a trend towards higher toxicities with TC6 that did not reach significance. Until a prospective randomized study comparing four vs six cycles of TC is conducted no definitive conclusions can be drawn, however, this study contributes to the current body of evidence that four cycles of TC is adequate and could potentially improve the quality of life of patients with early breast cancer. Table. Patient characteristics Patient characteristics including age, hormone status, stage, type of surgery, radiation, and treatment setting. Table. Adverse effects Adverse effect information obtained from physician documentation, and CBC reports documented at time of treatment with TC. Citation Format: Amith Ahluwalia, Michelle Koifman, Jaspreet Nannar, Bhavya Vachhani, Kanwal Ashraf, Maxim Shulimovich. Optimizing Taxane-based Chemotherapy in Breast Cancer: Retrospective study comparing 4 cycles of TC to 6 cycles of TC [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 PO4-02-11.

Abstract PO4-02-08: Outcomes of patients treated with chemotherapy for breast cancer during pregnancy compared with non-pregnant breast cancer patients treated with systemic therapy

Abstract Introduction: Prior studies comparing outcomes of patients diagnosed with and treated for breast cancer during pregnancy (PrBC) with those of non-pregnant patients with breast cancer report mixed results. Data are sparse for PrBC patients treated with systemic therapy, who may be at risk for poorer outcomes owing to the need to modify regimens or delay initiation of teratogenic agents until the postpartum period. This study aims to compare survival outcomes of PrBC patients treated with chemotherapy during gestation versus matched non-pregnant breast cancer patients treated with systemic therapy. Methods: Pregnant women with non-metastatic, non-inflammatory breast cancer treated with chemotherapy during gestation on prospective institutional protocols from 1989-2022 were identified. Two non-pregnant patients selected from a departmental database were matched to each PrBC patient using coarsened exact matching based on age at diagnosis (&amp;lt; 30 years old, 30-35, &amp;gt;35), year of diagnosis (&amp;lt; 1997, 1997-2004, &amp;gt;2004), stage at diagnosis (I, II or III), hormone receptor (HR) status, and Human epidermal growth factor receptor 2 (HER2) status. Retrospective chart review was performed to update vital status and other clinical data. Overall survival (OS) was calculated from diagnosis until last known vital status and compared using the Kaplan-Meier method and log-rank test. Results: 167 PrBC patients were matched to 334 non-pregnant patients (Table 1). Median age at diagnosis was 33 years for both cohorts (IQR: PrBC, 6; non-pregnant 7). Other characteristics are shown in Table 1. Median time from diagnosis to initiation of chemotherapy or oncologic surgery was 25 days (IQR 27) for PrBC patients and 27 days (IQR 37) for non-pregnant patients (p=0.61). Anti-HER2 therapy was deferred to the postpartum period for PrBC patients, with median time from diagnosis to therapy initiation of 73 days (IQR 190) compared with 63 days (IQR 143) for non-pregnant patients (p=0.36). Median follow-up was 4.5 years (IQR 9.0) for PrBC patients and 5.8 years (IQR 7.5) for non-pregnant patients (p=0.27). At last follow-up, 128 PrBC patients (77%) and 222 non-pregnant patients (66%) were alive. Median OS was 24.1 years (95% CI 15.8-undefined) for PrBC patients and 14.0 years (95% CI 10.8-33.8) for non-pregnant patients. OS did not differ significantly between cohorts (p=0.12). Conclusion: This retrospective, matched cohort study suggests that PrBC patients treated with chemotherapy during gestation have comparable OS compared with non-pregnant breast cancer patients treated with systemic therapy, despite treatment modifications and delayed initiation of teratogenic agents. This is the largest reported cohort of PrBC patients treated with a standardized chemotherapy protocol during gestation and therefore adds valuable insight into outcomes of this uncommon presentation of breast cancer. Continued study is needed to determine whether longer-term outcomes are similar, particularly for patients with triple-negative breast cancer who did not receive immunotherapy during pregnancy. Table 1 Baseline characteristics Citation Format: Helen Johnson, Carla Warneke, Ashley Martinez, Jennifer Litton, Oluchi Oke. Outcomes of patients treated with chemotherapy for breast cancer during pregnancy compared with non-pregnant breast cancer patients treated with systemic therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-02-08.

Abstract PO3-23-03: Radar reflectors for marking of target lymph nodes in patients receiving neoadjuvant chemotherapy for breast cancer – a subgroup analysis of the prospective AXSANA (EUBREAST-03) trial

Abstract Background: Surgical staging procedures of the axilla in breast cancer patients converting from a clinically positive (cN+) to a clinically negative (ycN0) lymph node status during neoadjuvant chemotherapy (NACT) vary across countries and within individual countries. The international prospective AXSANA (EUBREAST-03) study aims at comparatively evaluating long-term outcomes of different staging procedures such as axillary lymph node dissection (ALND), sentinel lymph node biopsy (SLNB), target lymph node biopsy (TLNB) and targeted axillary dissection (TAD). The comparison of marking techniques for the target lymph node (TLN) is a secondary endpoint. In this subgroup analysis, we report on the largest yet prospective cohort of patients receiving a radar reflector for marking of the TLN prior to NACT. Methods: The AXSANA study is an international prospective cohort study including cN+ patients converting to ycN0 status and treated with different axillary staging techniques according to the standard at their treating institution. The study was initiated by the EUBREAST network and started enrollment in August 2020. Eligible patients have cT1-4c tumors, initially present with axillary lymph node metastasis and receive neoadjuvant chemotherapy. Patients converting to ycN0 status are followed up for 5 years irrespectively of the ypN status. In the present subgroup analysis, only patients with a TLN marked by a radar reflector were included. We prospectively examined the retrieval rate of radar reflectors and the identification rate of the TLN (defined as unequivocal removal of the lymph node, i.e., the presence of lymphatic tissue in the TLN specimen and/or pathological confirmation of post-NACT changes typical for metastatic lymph nodes responding to treatment). Results: A TLN was marked using a radar reflector in 74 patients prior to NACT. The median age was 52 years (range: 32-77). The most common subtype was no special type in 68 (92%) patients and invasive lobular cancer in 7 (7%) patients. Most patients (n = 44, 59%) had one suspicious node at time of diagnosis, followed by two (n = 15, 20%), three (n = 10, 14%) or ≥ four suspicious nodes (n = 5, 5%). Only one TLN was marked in 73 (99%) patients and two nodes were marked in one patient (1%). Fifteen patients (20%) had a MRI between marker placement and surgery. In 4 out of 15 cases (27%), MRI artifacts were described. However, the assessment of MRI was limited due to artifacts only in one out of these four patients (25%). Out of the 74 patients with radar reflector marked TLN, 45 (61%) had undergone final surgery at the time of analysis and 29 (39%) are still under NACT. 36 out of 45 patients (80%) who received final surgery converted to ycN0. Most patients had undergone a TAD (n = 41, 91%), followed by TLNB in 7% (n = 3) and upfront ALND in 2% of cases (n = 1). All radar reflectors were successfully removed. In 44 out of 45 patients (98%) the TLN was unequivocally identified and removed. In one patient the tissue specimen containing radar reflector consisted of fat tissue and no lymphatic tissue was identifiable, so it remains unclear whether the TLN was excised, or the reflector might have dislocated. 29 patients (65%) had converted to ypN0 status. Conclusion: To the best of our knowledge this is the largest prospective series of patients receiving a radar reflector for the marking of TLN prior to NACT for breast cancer. The removal rate of the marker and the detection rate of the target node were very high. Our data demonstrate that radar reflectors are a reliable tool for marking of target lymph nodes before neoadjuvant treatment. Citation Format: Maggie Banys-Paluchowski, Steffi Hartmann, Jana de Boniface, Oreste Davide Gentilini, Timo Basali, Elmar Stickeler, Michael Untch, Franziska Ruf, Sarah Fröhlich, Marc Thill, Michael P. Lux, Florentia Peintinger, Guldeniz Karadeniz Cakmak, Isabel Rubio, Michalis Kontos, Rosa Di Micco, Dawid Murawa, Ellen Schlichting, Bilge Aktas Sezen, Achim Rody, Dagmar Langanke, Nana Bündgen, Jose Ignacio Sanchez-Mendez, Renu Buss-Steidle, Christine Mau, Nana Buchmann, Sabine Riemer, Marit Helene Hansen, Nina Ditsch, Thorsten Kühn. Radar reflectors for marking of target lymph nodes in patients receiving neoadjuvant chemotherapy for breast cancer – a subgroup analysis of the prospective AXSANA (EUBREAST-03) 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 PO3-23-03.

Abstract PO5-17-12: Impact of HER2-low status on axillary response and surgical management after neoadjuvant chemotherapy in early breast cancer

Abstract Background: Breast cancer (BC) with low expression of HER2 (HER2-low) might constitute a group of tumors with unique clinical and biological characteristics. Little is known about axillary downstaging and nodal surgical outcomes in HER2-low BC after neoadjuvant chemotherapy (NACT). The aim of this study was to evaluate axillary response and surgical management of the axilla in HER2-low BC patients submitted to NACT. Methods: In this cross-sectional single center study, we consecutively included all patients diagnosed with early HER2-negative BC between 2017 to 2021 that were treated with NACT. Patients must have biopsy-confirmed stage II-III BC, submitted to breast surgery after NACT. Clinical and pathological response in the axilla, type of axillary surgery, and surgical outcomes data were collected. HER2-low was defined by IHC score 1+, or 2+ ISH non-amplified; HER2-zero was defined by IHC score 0. Pathological response was determined locally. Results: At diagnosis, 291 patients had clinically involved axillary nodes (cN1: 69.4%; cN2: 25.1%; cN3: 5.5%). Among 136 patients eligible for SLN biopsy after NACT, 77 (26.5%) had pathologically negative SLN. Of those submitted to upfront axillary dissection (n=154), 52 (33.7%) had pN0 disease. In total, 129 (44.3%) patients with clinically involved axillary lymph nodes at diagnosis were converted to cN0 after NACT. There was no difference in the rate of axillary downstaging between HER2-low and HER2-zero tumors, 17.8% vs 26.5%, respectively (p=0.0026). 236 patients were submitted to sentinel lymph node biopsy (SLN), of whom 214 (81.4%) with blue dye-only, 40 (15.2%) with radioactive isotope, and 7 (2.7%) with dual tracer. SLN detection failure were reported for 12 patients (0.046%). Mean number of lymph nodes retrieved were 2.7. Most patients had a negative SLN biopsy (180/263; 68.4%), of whom 91 (50.6%) were HER2-low and 89 (49.4%) were HER2-zero. Positive SLN biopsy were reported in 83 patients (isolated tumor cells: 20,5%; micrometastasis: 24.1%; macrometastasis: 55.4%), with capsular extravasation in 25.3%. A positive SLN biopsy occurred in 61.4% of patients with HER2-low tumors, and in 38.5% of patients with HER2-zero tumors. Among patients with a positive SLN biopsy (n=83), 67 were submitted to axillary dissection, of whom 39 (58.2%) had no additional nodes involved (HER2-low: 61.5%; HER2-zero: 38.4%). Considering N0 tumors at diagnosis, 127 patients were submitted to SNL, and only 18.9% had a positive result (HER2-low: 66.6%; HER2-zero: 33.3%). In the subgroup of initially cN+ disease, 136 (46.7%) underwent SLN biopsy, with 59 (43.4%) with a positive result (HER2-low: 59.3%; HER2-zero: 40.7%). Conclusions: Our results showed that HER2-low BC patients had a statistically significant lower frequency of axillary downstaging after NACT. More than 40% of patients with cN+ at diagnosis were downstaged to cN0 and were submitted to SNL biopsy. Axillary dissection were avoided in roughly 25% of patients with cN+ BC at initial staging. Citation Format: Leonardo Roberto da Silva, Guilherme Sartori, Susana Ramalho, Tomás Reinert, Mahira Lopes Da Rosa, Grazielle Morais Tavares, Higor Mantovani, Vivian Vasconcelos, Ana Elisa Ribeiro Da Silva Cabello, Guilherme Coelho, Jovana Mandelli, Facundo Zaffaroni, Carlos Barrios, Marcia Silveira Graudenz, César Cabello. Impact of HER2-low status on axillary response and surgical management after neoadjuvant chemotherapy in early 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 PO5-17-12.

Abstract PO1-28-08: The Efficacy and Safety Results of Neoadjuvant Phase II study of Anlotinib plus Sintilimab Combined with Chemotherapy in Triple-negative Breast Cancer (NeoSACT)

Abstract Background: In triple-negative breast cancer (TNBC), the co-administration of programmed mortality 1 (PD-1) inhibitors and chemotherapy has demonstrated enhanced pathological complete response (pCR) rates and improved event-free survival (EFS). Previous research has suggested that antiangiogenic agents possess the ability to normalize aberrant tumor vasculature, thereby converting the immune-suppressive tumor microenvironment into an immune-supportive one. This study aims to assess the effectiveness and safety of combining the neoadjuvant small-molecule antiangiogenic drug Antilotinib with the PD-1 inhibitor Sintilimab and chemotherapy. Methods: In this study, a single-arm, open-label, phase II trial was conducted to evaluate the effectiveness of Anlotinib plus Sintilimab, in conjunction with nab-paclitaxel and carboplatin, followed by epirubicin and cyclophosphamide, in eligible patients with stage II-III TNBC. The treatment regimen consisted of four cycles of nab-paclitaxel (100 mg/m² on day 1, 8 and 15) plus carboplatin (AUC 5) every 21 days, followed by four cycles of epirubicin (90 mg/m2) plus cyclophosphamide (600 mg/m2) every 21 days. Additionally, patients received Sintilimab (200mg) every 21 days and Antilotinib (12mg, po on day 1-14, every 21 days) for eight cycles. Patient enrollment was conducted according to a Simon two-stage design. The primary endpoint was the rate of pCR based on the definition of ypT0/Tis ypN0. Secondary endpoints included residual cancer burden (RCB), EFS, overall survival (OS), adverse events (AE), and immune response biomarkers. Results: Between September 2021 and August 2023, a cohort of 31 patients was enrolled, with a median age of 48 years (range: 30-70 years). Among the participants, 21 out of 31 (67.8%) presented with clinical stage II disease, 23 out of 31 (74.2%) had T2 tumors, and 19 out of 31 (61.3%) exhibited clinically positive lymph nodes. In the initial phase of the study, a total of 11 patients were evaluated, out of which 7 patients achieved a pathological complete response (pCR) after surgery. Consequently, 20 patients were included in the subsequent stage, and among the 19 patients who were evaluable, 13 achieved pCR. One participant withdrew from the study prematurely following the third cycle due to grade 3 liver impairment, resulting in the discontinuation of study therapy as well as subsequent surgery. In the intention-to-treat (ITT) population, the overall pCR rate was determined to be 64.5% (20/31, 95% CI 45.4% - 80.8%). Additionally, 80.6% (25/31, 95%CI 62.5% - 92.5%) of the patients were assessed as having a RCB score of 0 or 1. A total of 31 patients were subjected to adverse event assessment. Among them, 12 patients (38.7%) experienced one or more grade 3/4 adverse events (AEs) according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The grade 3/4 AEs encompassed rash (7 patients, 22.6%), anemia (4 patients, 12.9%), thrombocytopenia (3 patients, 9.7%), neutropenia (2 patients, 6.4%), leukopenia (2 patients, 6.4%), hypothyroidism (2 patients, 6.4%), and elevated AST/ALT (1 patient, 3.2%). Conclusions: The neoadjuvant regimen comprising the combination of Anlotinib and Sintilimab alongside chemotherapy demonstrated a pCR rate of 64.5%, with no observed emergence of novel toxicity signals. Ongoing investigations encompass biomarker assessments and survival analyses. Pertinent clinical trial details can be found under the identifier NCT04877821. Citation Format: Liulu Zhang, Mei Yang, Ciqiu Yang, Teng Zhu, Hong-Fei Gao, Kun Wang. The Efficacy and Safety Results of Neoadjuvant Phase II study of Anlotinib plus Sintilimab Combined with Chemotherapy in Triple-negative Breast Cancer (NeoSACT) [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 PO1-28-08.

Abstract PO2-03-06: Pathological complete response with chemotherapy and immune checkpoint inhibition in triple negative inflammatory breast cancer (TN-IBC)

Abstract BACKGROUND: Patients with stage III inflammatory breast cancer (IBC) are treated with tri-modality therapy consisting of neoadjuvant systemic therapy followed by modified radical mastectomy and post-mastectomy radiation therapy. Triple negative IBC (TN-IBC) is the subtype of IBC associated with the worst survival outcomes. Pathological complete response (pCR) rates after neoadjuvant chemotherapy have been historically low, with reports ranging between 13% and 42%. It is unknown if the addition of immune checkpoint inhibition to chemotherapy leads to improved pCR rate in TN-IBC as these patients were underrepresented in the seminal studies that led to the approval of chemoimmunotherapy for high-risk early-stage triple negative breast cancer (TNBC). METHODS: We conducted a retrospective analysis of patients with stage III TN-IBC who underwent breast surgery after receiving neoadjuvant chemoimmunotherapy. Patients were seen at Dana-Farber Cancer Institute (DFCI) or MD Anderson Cancer Center (MDACC). The analysis population consisted of all patients that were seen at either institution no more than 30 days after starting immunotherapy. The primary objective was the estimation of the pCR rate. An additional cohort of patients with TN-IBC treated with neoadjuvant chemotherapy and pembrolizumab while participating in the multi-institutional PELICAN trial (NCT03515798) will be added to the analysis at the time of the meeting. RESULTS: Thirty-seven patients (16 DFCI, 21 MDACC) were identified as having stage III TN-IBC and having received neoadjuvant chemoimmunotherapy. Twenty-five patients met criteria for inclusion in the analysis population. Patients in the DFCI cohort initiated treatment with chemoimmunotherapy between May 2021 and June 2022, and in the MDACC cohort between June 2021 and October 2022. Most patients were White (N=20, 80%), premenopausal (N=15, 60%) and overweight/obese (N=19, 76%). All patients received pembrolizumab-based therapy (Table 1). Among the 25 patients in the analysis population, 10 (40%) (95% CI: 21% to 61%) achieved a pCR, 6 patients experienced RCB-II and 9 RCB-III. At the time of last follow up, 84% of patients were alive. The results will be updated at the time of the meeting to include an additional cohort of 17 patients from the PELICAN trial. CONCLUSIONS: The addition of immune checkpoint inhibition to neoadjuvant chemotherapy led to a higher pCR rate in TN-IBC than most historical estimates. However this is still lower than what has been reported in TNBC in general. The investigation of novel systemic therapies is warranted in TN-IBC. Table 1. Patient characteristics and treatment received (analysis population) Citation Format: Filipa Lynce, Samuel Niman, Anthony Gonçalves, Megumi Kai, Sean Ryan, Elizabeth Troll, Rachel Layman, Antonio Giordano, Azadeh Nasrazadani, Faina Nakhlis, Jennifer Bellon, Laura Warren, Caroline Block, Susan Schumer, Anthony Lucci, Savitri Krishnamurthy, Florence Lerebours, Florence Dalenc, Christelle Levy, Thierry Petit, Marianne Leheurteur, Thomas Bachelot, Olivier Trédan, Sylvain Ladoire, Leonor Lopez Almeida, Christophe Zemmour, Sara Tolaney, Vicente Valero, François BERTUCCI, Meredith Regan, Wendy Woodward. Pathological complete response with chemotherapy and immune checkpoint inhibition in triple negative inflammatory breast cancer (TN-IBC) [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 PO2-03-06.

Abstract PO5-16-09: Associations of age, body mass index, diabetes and hypertension with relative dose intensity among women receiving anthracycline- and/or taxane-based chemotherapy for invasive breast cancer

Abstract Research suggests that medical comorbidity is associated with reduced relative dose intensity (RDI) in patients receiving chemotherapy for treatment of breast cancer. We aimed to determine factors associated with RDI of specific chemotherapy drugs in anthracycline- and/or taxane-based regimens. Women with a diagnosis of lymph node positive, invasive breast cancer who received neoadjuvant or adjuvant chemotherapy with either doxorubicin (DOX) + paclitaxel (PAC) or docetaxel (DOCE)-containing regimens at a single centerfrom2012 to2019 were included in this retrospective study. Age, race, comorbidities, height, weight, and chemotherapy regimen and dose were abstracted from the electronic health record. BMI was calculated using height and weight measured in clinic at the time initial chemotherapy orders were written and categorized according to US national guidelines (18.5 to &amp;lt; 25, 25 to &amp;lt; 30, and &amp;gt;30kg/m2). Presence of diabetes (DM) and hypertension (HTN) at time of diagnosis were determined by chart review. The oncologists’ initial chemotherapy orders (dose and duration) were used as the basis for RDI calculations. Cumulative actual dose received and duration of treatment were compared to planned dose and duration for individual chemotherapy drug and by regimen (DOX+PAC vs. DOCE). Associations between patient characteristics and RDI were evaluated in bivariate and multivariable analyses. A total of 230 women met the inclusion criteria, with 125 receiving a DOX+PAC regimen and 105 receiving a DOCE-based regimen. A higher percentage of women on DOX+PAC received &amp;gt;85% RDI compared to women receiving DOCE (80.8% vs 67.6%). Women aged 65+ years had lower median RDI [IQR] for DOCE than younger women (0.83 [0.67 - 0.98] vs 0.94 [0.84 - 1.00], p = 0.04), and a lower percentage in the older group received &amp;gt;85% RDI (35.3% vs 73.9%, p&amp;lt; 0.01). Median RDIs of PAC and DOX+PAC were lower for Black women than for White and Asian women (PAC: 0.91 [0.75 - 1.00] vs 1.00 [0.89 - 1.00], p = 0.02, DOX+PAC: 0.92[0.87-0.99] vs. 0.97 [0.91-1.00], p = 0.03), and the percent of Black women receiving &amp;gt;85% RDI of PAC was also lower (55.3% vs 77.6%, p = 0.01). BMI category was associated with median RDI for PAC (p= 0.03) and DOX+PAC (p = 0.01), with women in the &amp;gt;30kg/m2 category having the lowest median RDIs and PAC RDI &amp;gt;85% (p &amp;lt; 0.01). Median RDI of DOX+PAC was lower for women with DM (0.89 [0.84-0.92] vs. 0.96 [0.88-1:00], p = 0.03), and a lower percentage of women with DM received DOX RDI &amp;gt;85% compared to women without DM (66.7% vs 91.6%, p &amp;lt; 0.01). Median RDI was lower among women with HTN compared to women without for PAC (0.85 [0.73 - 1.00] vs 0.98 [0.83 - 1.00], p = 0.01) and DOX+PAC (0.91 [0.84 - 0.97] vs 0.97 [0.90 - 1.00], p = 0.01), and a lower percentage of women with HTN received &amp;gt;85% RDI for PAC (50.0% vs 73.3%, p = 0.01). Multiple logistic regression models adjusted for age (continuous), race, BMI (continuous), DM, and HTN had modestly improved predictive value compared to null models (McFadden’s R2 = 0.10 to 0.19); each year of increased age was associated with lower odds of RDI &amp;gt; 85% for DOX (OR [95% confidence interval] 0.91 [0.84-0.97], p = &amp;lt; 0.01), DOX+PAC (0.95 [0.90-0.99], p = 0.02), and DOCE (0.93 [0.88-0.97], p &amp;lt; 0.01), and DM with lower odds for DOX (0.26 [0.07-0.95], p = 0.04). Our findings of associations between increasing age, Black race, BMI, DM, and HTN and reduced RDI are consistent with prior research and present new data regarding associations between medical comorbidities and individual components of chemotherapy regimens. Citation Format: Heather Wopat, Annette Aldous, Adam Ciarleglio, Kendall Anderson, Kim Robien. Associations of age, body mass index, diabetes and hypertension with relative dose intensity among women receiving anthracycline- and/or taxane-based chemotherapy for invasive 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 PO5-16-09.

Abstract PO4-02-09: Clinical outcomes of neoadjuvant chemotherapy in HER2-low early breast cancer

Abstract BACKGROUND: According to immunohistochemistry (IHC) expression of HER2 receptor, breast cancer (BC) can be classified as either IHC score 0, 1+, 2+ or 3+. Until recently, two distinct BC subtypes were recognized depending on the HER2 IHC expression and in situ hybridization (ISH) score: HER2 positive (IHC 3+ or IHC 2+ ISH-amplified) and HER2 negative (IHC 0, 1+ or 2+ ISH negative). More recently a new BC entity termed HER2-low was acknowledged, defined as either HER2 IHC 1+ or 2+ ISH-negative. Given that no treatment benefit was observed in HER2-low group of patients in the pivotal trastuzumab studies, many years had to pass before the discovery of antibody-drug conjugates such as trastuzumab deruxtecan, that led to a significant improvement in the clinical outcome of HER2-low BC, compared to standard therapy options. It is still debated whether HER2-low BC represents a distinct biological subtype. The aim of this study was to determine whether there is an impact of HER2-low status on the effect of neoadjuvant chemotherapy (NACT) and its primary indicator - the rate of the pathologic complete response (pCR). METHODS: A retrospective study of 363 BC cases who received NACT between January 2020 and December 2022 at University Hospital Centre Zagreb, Croatia, was conducted with prior Ethics Committee approval. Histopathological characteristics of tumours available from the hospital information system (BIS), including hormone receptor status (ER, PR), HER2 status and Ki-67 at the time of diagnosis and after neoadjuvant treatment, as well as pCR rates, were analysed. pCR rates were calculated for HER2-low and HER2 0 cases. Chi square test was used to analyse association between pCR rate and HER2 status. RESULTS: After exclusion of HER2 positive BC cases, as well as cases with missing data, a total of 215 patients were included in the analysis. Of those, 101 (47%) were HER2-low, and 114 (53%) were HER2 negative. The majority of patients (N=151, 70.2%) had luminal BC, while 64 (29.8%) patients had triple negative BC (TNBC). In the luminal group, 86 cases (57%) were HER2-low, and 65 (43%) were HER2 0. In the TNBC group, 15 cases (23.4%) were HER2-low and 49 (76.6%) were HER2 0. The rate of pCR among luminal subtypes was 6.2% for HER2-low tumours, and 15.4% for HER2 0 tumours (p=.051559), approaching statistical significance. In the TNBC group, the pCR rate for HER2-low group was 60%, compared to 40% in the HER2 0 group, trending towards, but not reaching statistical significance (p=.191564). CONCLUSION: A trend toward higher pCR rates after neoadjuvant chemotherapy was observed in the luminal HER2 0 group compared to HER2-low luminal BC, almost reaching statistical significance. Interestingly, in TNBC there was a trend towards higher pCR rates among the HER2-low group, although a small number of patients precludes any definitive conclusions. Further trials that include novel targeted therapies are needed, as that might lead to significant changes in therapeutic approach, as well as clinical outcome of HER2-low BC patients. Citation Format: Dora Gudelj, Katarina Čular, Lea Toula, Marija Križić, Marina Popović, Natalija Dedić Plavetić, Ana Kelečić, Gordana Ivanac, Majana Soče, Iva Kukal Gjergjaj, Tajana Silovski. Clinical outcomes of neoadjuvant chemotherapy in HER2-low early 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 PO4-02-09.

Abstract PO2-01-03: Efficacy of dose-dense and anthracycline-free regimens in neoadjuvant chemotherapy of HER2-positive breast cancer: a single-center matched-cohort study. Preliminary results

Abstract Introduction: The efficacy of dose-dense (dd) adjuvant chemo has been proved in numerous clinical trials and meta-analysis. However, it remains unclear whether the intensification of AC (doxorubicine/cyclophosphamide) regimen affects the rate of pathological complete response (pCR) in HER2+ subtype, since the efficiency of thе ddAC-THP (docetaxel/trastuzumab/pertuzumab) regimen with dual anti-HER2-blocade in the neoadjuvant (NA) setting has not been assessed. Anthracycline (A)–containing and A-free regimens (TCHP -docetaxel/carboplatin/trastuzumab/pertuzumab) are considered equivalent, although there are no direct comparative studies to date. Methods: The aim of the study was to assess the rate of pCR of ddAC (once every 2 weeks)-THP NA regimen in comparison with ACq3w (once every 3 weeks)-THP and A-free TCHP regimen in HER2+ stage II-III breast cancer (BC). The study included patients with early HER2+ BC who received NA chemo in a single center from Jan 2017 to Nov 2022. Statistical hypothesis. The study has a 2-step design. It is assumed that the rate of pCR with ddAC will be ≥65%, and with ACq3w≤50%. With a unilateral type I error (α) = 0.05 and a type II error (β) = 0.2, 170 patients should be included in each group. In the absence of significant differences between ddAC and 4ACq3w, groups may be merged into one cohort and compared with TCHP group. It is assumed that A-containing regimens (H1 - pCR 55%) are not inferior to A-free regimen (H0 - pCR 55%). A non-inferiority design is planned, with delta 15%, type I error (α) = 0.05 and type II error (β) = 0.2, 173 people in each group should be included. Here we present preliminary results. Results: A total of 400 patients were included, of which 138 received 4xddAC- 4xTHP, 102 – 4xACq3w-4 x THP, 160 – 6xTCHP. The pCR rate in the whole ddAC-THP group was 55,8%. The majority of patients (77,5%) had stage III disease. After propensity matching analysis to adjust for selection bias 102 patients in each A-containing group were included in the final analysis. The pCR rate was 50% in the ddAC group vs 48% in the ACq3w group (p=0.67). Subgroup analysis, including T, N stage, age, ER status, G, ki67 revealed no advantage of ddAC regimen. Next, both A-groups were merged and after propensity matching analysis 143 patients were included both in A- and TCHP-group. The pCR rate was 53,8% in the A-group vs 60,1% in the TCHP group (p=0.34). Subset analysis demonstrated no benefit of A-regimen across subgroups. Conclusion: Our preliminary results suggest that A-containing and TCHP regimens appear to be equivalent in terms of pCR. In case of choosing AC-THP for NA chemo there’s no need to perform the AC arm in dd way since it does not improve efficacy. Citation Format: Elena Kovalenko, Yaroslav Zhulikov, Maxim Khoroshilov, Igor Vorotnikov, Alexander Petrovskiy, Elena Artamonova. Efficacy of dose-dense and anthracycline-free regimens in neoadjuvant chemotherapy of HER2-positive breast cancer: a single-center matched-cohort study. Preliminary results [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 PO2-01-03.

Abstract RF01-06: Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design

Abstract Background: Combining Immune checkpoint blockade (ICB) with chemotherapy may significantly improve efficacy in patients with breast cancer. Metronomic chemotherapy is based on more frequent and low-dose drug administrations compared with conventional chemotherapy. Some clinical studies with small samples have tried the combination of metronomic chemotherapy and ICB in patients with advanced tumors. However, whether metronomic chemotherapy is more suitable for ICB than conventional chemotherapy is still unclear. Thus, we performed the first clinical trial, to our knowledge, of metronomic chemotherapy combined with PD-1 blockade comparing with the efficacy of combined conventional chemotherapy and ICB. Methods: This study is a multicenter randomized phase 2 trial using a multi-arm design with Bayesian adaptive randomization and efficacy monitoring. Eligible patients have advanced HER2 negative breast cancer, with no more than one prior line of standard chemotherapy. Patients were randomized to 5 groups: ① metronomic vinorelbine (NVB, 40 mg/day, TIW) monotherapy (the control cohort); ② NVB + Toripalimab (anti-PD1 antibody, 240 mg Q3W); ③Bevacizumab (5 mg/kg Q3W) + NVB+ Toripalimab (the BEV cohort); ④ Cisplatin (50mg/m Q3W) + NVB + Toripalimab (the DDP cohort), ⑤Cyclophosphamide (50mg/day, QD) + Capecitabine (500 mg, TID) + NVB+ Toripalimab (the VEX cohort). The primary endpoint is disease control rate (DCR), and secondary endpoints are objective response rate (ORR), progression free survival (PFS), and overall survival (OS). The safety profile has also been assessed. Mass cytometry time-of-flight (CyTOF) analyses of paired blood samples were performed to demonstrate dynamic changes in systemic immune profile. Results: A total of 103 patients were randomized. Characteristics were as expected for advanced breast cancer and balanced between cohorts. Adverse events of any grade occurred in 64 patients, with 5.2% grade &amp;gt;3. The rate of nausea was significantly higher in the cisplatin cohort than in the others (P&amp;lt; 0.001). Toripalimab was not associated with any previously unreported toxicity. Among the five treatment cohorts, the VEX cohort and the cisplatin cohort had the highest DCR, 69.7% (95% CI 51.7–85.9%) and 73.7% (95% CI 56.1–88.7%), respectively. Followed by the bevacizumab cohort, DCR is 55.7% (95% CI 37.4%–73.6%). Most objective responses were observed in the VEX cohort (ORR: 18.5%; 95% CI 5.6–34.1%), followed by cisplatin (ORR 14.5%; 95% CI 3.3–29.0%). It is worth noting that the PFS of patients in the VEX cohort was the longest, reaching 6.6 months (95% CI 4.0-5.9), followed by 4.0 months (95% CI 2.4-10.4) in patients of the bevacizumab cohort. The PFS of patients receiving the cisplatin regimen was relatively short, only 3.5 months (95% CI 2.2-5.3). Similarly, patients in the cisplatin cohort had shorter OS than those in the VEX and bevacizumab cohorts. In the TNBC subgroup, again, patients in the VEX cohort had the highest DCR (74.1%, 95%CI 47.9%-95.4%) and longest PFS (9.8 months, 95%CI 3.8-21.9). We obtained over 63 million cells in total and clustered CD45+ immune cells into 32 clusters. The systemic immune profile of patients changed dramatically over 2 cycles of PD-1 blockade. However, only the change of cluster 30 differed between responders and non-responders. This is a group of intermediate monocytes with a high expression of CD38, which decreased in responders but significantly increased in non-responders. CD38-NAD+ axis regulates the PD1+ exhausted T cell function. Meanwhile, the overall expression of CD38 in monocytes was significantly increased by DDP and BEV treatment compared with baseline, but not in the VEX groups. DDP significantly increased the expression level of CD38 on NK cells, while BEV or VEX treatment did not affect it. Conclusions: These data suggest promising clinical efficacy and evidence of cooperativity between metronomic VEX chemotherapy and PD-1 blockade. Citation Format: Hongnan Mo, Xiaoying Sun, Jingtong Zhai, Jiashu Han, Hewei Ge, Yuhan Wei, Xiuwen Guan, Haili Qian, Fei Ma. Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design [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 RF01-06.

Abstract PO3-06-07: Efficacy and safety of sintilimab in combination with anlotinib plus metronomic chemotherapy in advanced triple negative breast cancer (SPACE): preliminary results of a single-arm, multicenter phase II trial

Abstract Background: Antiangiogenic drugs have demonstrated synergistic effect with anti-PD-1 antibody in advanced triple negative breast cancer (TNBC). Anlotinib is an oral multi-target tyrosine kinase inhibitor (TKI) that strongly inhibits VEGFR, PDGFR, FGFR, and c-kit. Preclinical studies showed that metronomic chemotherapy inhibited angiogenesis and enhanced the efficacy of immunotherapy in TNBC via modulation of the tumor immune microenvironment. We hereby conducted a single-arm, multicenter, phase II trial to investigate the efficacy and safety of sintilimab (anti-PD-1 antibody) plus anlotinib and metronomic chemotherapy as a potential novel therapeutic strategy in advanced TNBC and explore potential biomarkers. Methods: Forty-four cases were planning to be included in this trial. The eligible patients who had received no more than two lines of chemotherapy for metastatic disease were enrolled and received sintilimab (200 mg iv q3w) and anlotinib (12 mg po d1-14 q3w) plus capecitabine (500 mg po, tid) or vinorelbine (40 mg po, tiw) until disease progression or intolerable toxicity. The primary endpoint is objective response rate (ORR) and secondary endpoints are disease control rate (DCR), progression free survival (PFS), and overall survival (OS). The safety profile has also been assessed. Results: As of April 2023, a total of 44 patients were enrolled, and 42 patients were evaluable for efficacy. 3 patients (7.1%) achieved complete response (CR). 6 patients (14.3%) achieved partial response (PR). 25 patients (59.5%) achieved stable disease (SD).The ORR is 21.4% (95%CI 0.103-0.368) and DCR is 81.0% (95%CI 0.810-0.659). The median PFS was 5.06 months (95%CI 2.051-8.069). The most common grade 1 or 2 adverse events (AEs) include elevated thyroid stimulating hormone (52.38%, 22/42), elevated bilirubin (23.81%, 10/42), hand-foot syndrome (22.22%, 8/42), leukopenia (16.67%,7/42), nausea (14.29%, 6/42). Grade 3 AEs include elevated bilirubin (2.38%, 1/42), hypertension (2.38%, 1/42) and herpes zoster (2.38%, 1/42). No grade 4 or 5 AEs occurred. Conclusions: Our date showed that sintilimab in combination with anlotinib plus metronomic chemotherapy have shown favorable efficacy and acceptable safety profile in patients with advanced TNBC. Clinical trial information: ChiCTR2100044725 Citation Format: huihui Li, Dongdong Zhou, Zeshun Yv, Yuqian Liao, Jie Huang, Shujuan Sun, fangchao zheng, Baojiang Li, Shu Fang, Ling Qiang, Guohua Ren, Bing Bu, Pengfei Qiu, Xinzhao Wang, Chao Li, Fangli Cao, Qian Shao, Dali Han, Lihua Song, Baoxuan Zhang, Bingjie Fan, Liang Xu, Xuemei Xie, Xianguang Zhao, Lanping Liu, Wanlong Li, Zhenbo Wang, Changmin Liu, Hui Fu, Xiao Sun, Zhiqiang Shi, Fengxiang Li. Efficacy and safety of sintilimab in combination with anlotinib plus metronomic chemotherapy in advanced triple negative breast cancer (SPACE): preliminary results of a single-arm, multicenter 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 PO3-06-07.

Abstract PO5-02-02: LyKi1: a highly predictive immune-based score of pathological response to chemotherapy in luminal breast cancer

Abstract Background: Identifying which luminal breast cancer (BC) patients will benefit from (neo)adjuvant chemotherapy still remains a challenge. Efficient predictive tests and genomic signatures are still lacking. Because neoadjuvant chemotherapy (NACT) constitutes an in vivo chemotherapy-sensitivity test, we used the pre-treatment core biopsies to identify predictive factors of pathological response in luminal HR+/Her2- BC. Analyses on sTILS and TIL subtypes (CD3, CD4, CD8, CD20) are rare in luminal BC while a predictive value has been reported in TNBC and Her-2 positive BC. Patients and Methods: We performed a retrospective analysis of 211 patients treated with NACT followed by surgery for a T0-T4 luminal (HR+/Her-2-) breast cancer. Association of anthracyclin and taxane was used in 99% of cases. Median age was 48.4 yo (28 – 76). Initial clinical stage was: I: 0.5%, II: 67%; III: 33%. Biopsy analyses were the followings: NST carcinomas: 90%; luminal B: 82%; E&amp;E grade I/II/III: 10%/57%/32%; KI-67 &amp;gt; 20%: 74%. After NACT, RCB 0-1 was observed in 32 cases (15.2%) and pCR in 19 (9.0 %) cases. All pre-therapeutic biopsies were reviewed for pathological factors, blinded to the patients’ outcomes. Clinico-pathological analyses were performed using standard methods. sTILs were estimated on H&amp;E slides. Intratumoral CD3, CD4, CD8 and CD20 infiltrates were carried out by an independent laboratory using a machine learning model for automated and quantitative evaluation based on digital IHC stains. Correlation between sTILs and TIL subtypes were assessed by Spearman’s coefficient. Predictive factors of RCB 0/1 were explored using unconditional logistic regression analysis. After selection on univariate analysis (p&amp;lt; 0.05), multivariate prognostic models were developed using stepwise backward variable elimination process and compared using area under the curve (AUC). Results: sTILs levels ≥ 10% were observed in 15.2% of biopsies. 42 % of tumors had ≥ 10 % CD3-positive cells, 46% for CD4, 38% for CD8, and 8% for CD20. A high level of correlation was observed between these different markers (Spearman’s coefficient ≥ 0.73 for each comparison). By univariate analysis, significant factors (p&amp;lt; 0.05) associated with RCB 0-1 were: age, mitotic index (1 vs 2 vs 3), aneuploidy (1-2 vs 3), differentiation (1-2 vs 3), E&amp;E grade (1-2 vs 3), mitotic count, Ki-67, Magee equation 3, phenotypic group (luminal A vs B), ER, sTILs and each TIL subtype. Age, E&amp;E grade, Ki-67, Magee equation 3, sTILs and all TIL subtypes were selected for multivariate analysis. As TIL subtypes were highly correlated, different predictive models could be performed. The model we selected (called LyKi1) was constructed based on CD8 [OR 2.24 (95%CI 1.55-3.25; p&amp;lt; 10-4)], E&amp;E grade [OR 3.00 (95%CI 1.22-7.42; p=0.017)] and Ki-67 [OR 1.74 (95%CI 1.09-2.76; p=0.019)]. It was highly significantly associated with RCB 0-1, with an AUC value of 0.856 (95%CI 0.756-0.916). For instance, LyKi1 could isolate a group of 30% of patients that achieved RCB 0-1 in 39.7% of cases vs 4.7% for the 70% of patients with lowest LyKi1 scores. pCR rates were 25% and 2%, respectively. Importantly, prediction value of LyKi1 remained very high if restricted to luminal B tumors (AUC 0.817; 95% CI: 0.741-0.894). Ability to predict pCR was also very high (AUC 0.837 (95%CI: 0.750-0.924) in this phenotype). Conclusion: This retrospective analysis clearly highlights the important predictive role of sTILs and TIL subpopulations for the response to an anthracyclin-taxane based regimen in a neoadjuvant setting for luminal breast cancer. Within this cohort, LyKi1 score (combining CD8, grade and Ki-67) has a very high value to predict pathological response to NACT in luminal breast cancer. Importantly, such score has to be validated in a multicentric prospective cohort and investigated in adjuvant setting. Citation Format: Marc Debled, Hugo Deboissy, Coralie Cantarel, Chloé Delfour, Léonie Alran, Marion Fournier, Nathalie Quenel-Tueux, Valérie Velasco, Foucault Chammings, Véronique Brouste, Monica Arnedos, Gaétan MacGrogan. LyKi1: a highly predictive immune-based score of pathological response to chemotherapy in luminal 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 PO5-02-02.