Predictors Of Response Research Articles

Longitudinal study of immunity to SARS-CoV2 in ocrelizumab-treated MS patients up to 2 years after COVID-19 vaccination.

(1) To plot the trajectory of humoral and cellular immune responses to the primary (two-dose) COVID-19 mRNA series and the third/booster dose in B-cell-depleted multiple sclerosis (MS) patients up to 2 years post-vaccination; (2) to identify predictors of immune responses to vaccination; and (3) to assess the impact of intercurrent COVID-19 infections on SARS CoV-2-specific immunity. Sixty ocrelizumab-treated MS patients were enrolled from NYU (New York) and University of Colorado (Anschutz) MS Centers. Samples were collected pre-vaccination, and then 4, 12, 24, and 48 weeks post-primary series, and 4, 12, 24, and 48 weeks post-booster. Binding anti-Spike antibody responses were assessed with multiplex bead-based immunoassay (MBI) and electrochemiluminescence (Elecsys®, Roche Diagnostics), and neutralizing antibody responses with live-virus immunofluorescence-based microneutralization assay. Spike-specific cellular responses were assessed with IFNγ/IL-2 ELISpot (Invitrogen) and, in a subset, by sequencing complementarity determining regions (CDR)-3 within T-cell receptors (Adaptive Biotechnologies). A linear mixed-effect model was used to compare antibody and cytokine levels across time points. Multivariate analyses identified predictors of immune responses. The primary vaccination induced an 11- to 208-fold increase in binding and neutralizing antibody levels and a 3- to 4-fold increase in IFNγ/IL-2 responses, followed by a modest decline in antibody but not cytokine responses. Booster dose induced a further 3- to 5-fold increase in binding antibodies and 4- to 5-fold increase in IFNγ/IL-2, which were maintained for up to 1 year. Infections had a variable impact on immunity. Humoral and cellular benefits of COVID-19 vaccination in B-cell-depleted MS patients were sustained for up to 2 years when booster doses were administered.

Programmed Death Ligand 1 Expression in Circulating Tumor Cells as a Predictor and Monitor of Response to Atezolizumab plus Bevacizumab Treatment in Patients with Hepatocellular Carcinoma

Programmed Death Ligand 1 Expression in Circulating Tumor Cells as a Predictor and Monitor of Response to Atezolizumab plus Bevacizumab Treatment in Patients with Hepatocellular Carcinoma

The value of biomarkers in the therapy of CRSwNP with biologicals-a long-term follow-up of dupilumab therapy.

Since its release, Dupilumab has shown great results in treating severe uncontrolled CRSwNP. However, there is a lack of real-world data beyond 12months of follow-up, and it is not clear to what extent biomarkers are appropriate for monitoring and predicting the Dupilumab therapy success. Hence, this study aims to analyze biomarkers for monitoring therapy, predicting therapy success and assess the effect of Dupilumab in real-world settings. The follow-up was performed with 104 patients retrospectively up to 22months, assessing SNOT-22, NPS, olfactometry, ACS, FEV-1, and blood biomarkers (total serum IgE, Eosinophils, ECP). Patients were divided into subgroups depending on their pretherapeutic biomarker levels and subsequent development was analyzed. There was substantially improvement in all clinical parameters up to 1year and then continuously up to month 22. Patients with initially elevated baseline blood eosinophil counts (> 0.5billion/L) had a trend of better SNOT-22 development after 1year (- 12.19 points, p = 0.03). The course of total serum IgE showed moderate correlation with almost all clinical variables obtained. Therapy was well tolerated with only mild and transient adverse events. Dupilumab has considerably reduced symptoms and disease severity even beyond 1year of treatment, supporting its role as targeted and effective treatment option for CRSwNP. Our data shows that total serum IgE is a promising biomarker for the monitoring during the treatment with Dupilumab. Elevated pre-therapeutic serum eosinophil counts may be a predictor of good subjective response to therapy. Larger cohorts and a long-term-follow-up over years are needed to further consolidate these findings.

Ratio of plasma IL-13/TNF- ∝ and CXCL10/CCL17 predicts mepolizumab and omalizumab response in asthma better than eosinophil count or immunoglobulin E level

To date, most studies to identify biomarkers associated with response to the anti-interleukin 5 agent, mepolizumab, and to the anti-immunoglobulin E agent, omalizumab have focused on clinically available biomarkers, such as the peripheral blood eosinophil counts (BEC) and total immunoglobulin E (IgE). However, these biomarkers often have low predictive accuracy, with many patients with eosinophilic or allergic asthma failing to demonstrate clinical response to mepolizumab or omalizumab respectively. In this study, we evaluated the association of baseline pre-biologic plasma levels of 26 cytokines and chemokines, including T-helper 1 (Th1)-, Th2-, Th17-related cytokines, and their ratios with subsequent clinical response to mepolizumab or omalizumab. We defined clinical response as a reduction in the baseline annual exacerbation rate by half or more over the one-year period following initiation of the biologic. Baseline levels of plasma IL-13 were differentially elevated in responders versus non-responders to mepolizumab and plasma CXCL10 levels were differentially elevated in responders to omalizumab. The ratio of IL-13/TNF-α had the best sensitivity and specificity in predicting response to mepolizumab and CXCL10/CCL17 to omalizumab, and these performed better as predictive biomarkers of response than BEC and IgE. Cytokines and chemokines associated with airway eosinophilia, allergic inflammation, or Th2 inflammation, such as IL-13 and CXCL10, may be better predictors of clinical response to mepolizumab and omalizumab, than IL-5 or IgE, the targets of mepolizumab and omalizumab.

Loss of copy numbers of retrotransposons (HERVK) on chromosome 7p11.2 impacts EGFR (Epidermal Growth Factor Receptor)-induced phenotypes for platinum sensitivity and long-term survival in ovarian cancer-A study from the OVCAD consortium.

We analyzed variations in the epidermal growth factor receptor (EGFR) gene and 5'-upstream region to identify potential molecular predictors of treatment response in primary epithelial ovarian cancer. Tumor tissues collected during debulking surgery from the prospective multicenter OVCAD study were investigated. Copy number variations in the human endogenous retrovirus sequence human endogenous retrovirus K9 (HERVK9) and EGFR Exons 7 and 9, as well as repeat length and loss of heterozygosity of polymorphic CA-SSR I and relative EGFR mRNA expression were determined quantitatively. At least one EGFR variation was observed in 94% of the patients. Among the 30 combinations of variations discovered, enhanced platinum sensitivity (n = 151) was found dominantly with HERVK9 haploidy and Exon 7 tetraploidy, overrepresented among patients with survival ≥120 months (24/29, p = .0212). EGFR overexpression (≥80 percentile) was significantly less likely in the responders (17% vs. 32%, p = .044). Multivariate Cox regression analysis, including age, FIGO stage, and grade, indicated that the patients' subgroup was prognostically significant for CA-SSR I repeat length <18 CA for both alleles (HR 0.276, 95% confidence interval 0.109-0.655, p = .001). Although EGFR variations occur in ovarian cancer, the mRNA levels remain low compared to other EGFR-mutated cancers. Notably, the inherited length of the CA-SSR I repeat, HERVK9 haploidy, and Exon 7 tetraploidy conferred three times higher odds ratio to survive for more than 10 years under therapy. This may add value in guiding therapies if determined during follow-up in circulating tumor cells or circulating tumor DNA and offers HERVK9 as a potential therapeutic target.

Prediction model for treatment response of primary membranous nephropathy with nephrotic syndrome.

To investigate the predictors and establish a nomogram model for the prediction of the response to treatment in primary membranous nephropathy (PMN) with nephrotic syndrome (NS). The clinical, laboratory, pathological and follow-up data ofpatients withbiopsy-proven membranous nephropathy at the Affiliated Hospital of QingdaoUniversity were collected. A total of 373 patients were randomly assigned into development group (n = 262) and validation group (n = 111). Logistic regression analysis was performed in the development group to determine the predictors of treatment response. A nomogram model was established based on the multivariate logistic regression analysis and validated in the validation group. The C-index and calibration plots were used for the evaluation of the discrimination and calibration performance, respectively. Serum albumin levels (OR = 1.151, 95% CI 1.078-1.229, P < 0.001) and glomerular C3 deposition (OR = 0.407, 95% CI 0.213-0.775, P = 0.004) were identified as independent predictive factors for treatment response in PMN with NS, then a nomogram was established combining the above indicators and treatment regimen. The C-indices of this model were 0.718 (95% CI 0.654-0.782) and 0.789 (95% CI 0.705-0.873) in the development and validation groups, respectively. The calibration plots showed that the predicted probabilities of the model were consistent with the actual probabilities (P > 0.05), which indicated favorable performance of this model in predicting the treatment response probability. Serum albumin levels and glomerular C3 deposition were predictors for treatment response of PMN with NS. A novel nomogram model with good discrimination and calibration was constructed to predict treatment response probability at an early stage.

Peripheral blood quantitation of CD26 positive leukemic stem cells as a predictor of tyrosine kinase inhibitor response in chronic myeloid leukemia.

Leukemic stem cells (LSCs) are the transcriptionally low/silent cells which are resistant to the tyrosine kinase inhibitor. These have been found to play a pivotal role in disease relapse in chronic myeloid leukemia (CML) cases. The present study evaluated the correlation of absolute CML-LSC count in the peripheral blood (PB) at diagnosis and achievement of major molecular response (MMR) at 12 months in patients of CML-CP. This was a prospective, observational, non-interventional single center study including newly diagnosed adult (>18 yrs) CML-CP patients. Absolute CD26 + CML-LSC quantification was done by multiparametric flow cytometry. Patients were treated with Imatinib treatment and subsequently monitored at 3-month intervals for BCR::ABL transcript levels. MMR was defined as a BCR::ABL1 transcript level of less than 0.1% on international scale. A total of 89 patients were enrolled in the study out of which 40.5% achieved MMR at 12 months. There was a significant difference in the median absolute CML-LSC count of the patients who achieved MMR at 12 months as compared to those who did not (58.5 vs 368.1 cells/μL; p value <0.001). Using a ROC analysis, a count of <165.69 CML LSC/μL was identified to have a sensitivity of 83.8% and specificity of 72.4%, in predicting the MMR at 12 months. Absolute CML-LSC count at diagnosis in the PB predicts the MMR achievement at 12 months. An absolute count of less than 165 cells/μL is highly predictive of achieving MMR at 12 months.

Tumor-infiltrating lymphocytes as a predictor of axillary and primary tumor pathological response after neoadjuvant chemotherapy in patients with breast cancer: a retrospective cohort study.

Tumor-infiltrating lymphocytes (TILs) can predict complete pathological response (pCR) of tumor in the breast but not so well-defined in the axilla after neoadjuvant chemotherapy. Since axillary surgery is being increasingly de-escalated after NACT, we aimed to investigate the relationship between TILs and pCR in the axilla and breast, as well as survival amongst NACT patients. Clinicopathological data on patients who underwent NACT between 2013 and 2020 were retrospectively examined. Specifically, pre-TILs (before NACT), post-TILs (after NACT) and ΔTIL (changes in TILs) were assessed. Primary endpoint was pCR and secondary endpoints were breast cancer-free interval (BCFI) and overall survival (OS). Two hundred and twenty patients with nodal metastases were included. Overall axillary and breast pCR rates were 42.7% (94/220) and 39.1% (86/220), respectively, whereas the combined pCR rate was 32.7% (72/220). High pre-TILs (OR 2.03, 95% CI 1.02-4.05; p = 0.04) predicted axillary pCR whereas, high post-TILs (OR 0.33, 95% CI 0.14-0.76; p = 0.009) and increased ΔTILs (OR 0.25, 95% CI 0.08-0.79; p = 0.02) predicted non-axillary pCR. TILs were not a significant predictor for BCFI and OS. This study supports the potential use of pre-TILs to select initially node-positive patients for axillary surgical de-escalation after NACT.

Clinical Response Predictive Model for Omalizumab in Moderate-to-Severe Asthma Patients

Objective. Our study aimed to develop a predictive model for evaluating the clinical response of omalizumab treatment in moderate-to-severe asthma patients. Methods. This single-center, prospective study collected patients who meet the diagnostic criteria for moderate-to-severe bronchial asthma set by the National Asthma Prevention and Treatment Group in 2016 in the first hospital affiliated with Soochow University. Patients recruited were treated with omalizumab once per four weeks; at the beginning of each injection, blood eosinophils and the level of total serum IgE (IU/mL) were tested. After four injections of omalizumab, asthma control test (ACT), the 15-item Mini Asthma Quality of Life Questionnaire (MiniAQLQ), global treatment effectiveness (GETE), and lung function of all patients were evaluated in the 16th week. We used the selection operator method to build a logistic model and evaluated the clinical response of omalizumab in these patients. Results. This study included 108 moderate-to-severe patients (aged 39.86 ± 14.59 years). Eighty-nine patients finished treatment for 16 weeks, and 74 patients (83.1%) had an excellent or good response. The serum level of total IgE increased significantly after injection of omalizumab, while blood eosinophils count decreased significantly from baseline. Using the GETE as a clinical outcome, several clinical variables were significant predictors of clinical response. The corrected AUC and Brier scores were 0.872 and 0.111, which showed good discrimination. Significant variables included age, weight, family allergic history, acute exacerbations, the ratio of total serum IgE level at the 4th week to the baseline level, forced expiratory volume in one second/forced vital capacity (FEV1/FVC), and commodities of rhinitis. Using the improvement in maximal expiratory flow 25% of the measured value to the predicted value (MEF25%pre) as clinical outcome, the significant variables included weight, duration of asthma, use of oral corticosteroids (OCS), total serum IgE level at the 4th week, and history of rhinitis. Its corrected AUC and Brier scores were 0.674 and 0.225 after internal validation. Conclusion. Omalizumab treatment remarkably improved asthma control and pulmonary function in Chinese patients with moderate-to-severe asthma. The response prediction model we developed provides convenient approaches to help identify better clinical response patients to omalizumab treatment.

Abstract PO2-04-01: Predictors of exceptional response to first line HER2-targeted therapy for metastatic breast cancer

Abstract Background HER2-targeted therapies have transformed the trajectory of HER2-positive (HER2+) metastatic breast cancer (MBC), with a subgroup of responders remaining on first line (1L) therapy for many years (yrs). Despite these promising outcomes, the paradigm remains palliative, with some patients (pts) receiving therapy indefinitely. Opportunities to interrupt therapy are controversial and anecdotal in the setting of a limited understanding of long-term responders and lack of predictive biomarkers. Methods We identified prevalent pts with HER2+ MBC seen and consented at Dana-Farber Cancer Institute between 2010 and 2023, regardless of the original date of MBC diagnosis. Exceptional responders (ExRes) were pts without evidence of progressive disease (PD) 3 yrs from initiation of 1L therapy for MBC. Conventional responders (ConRes) were pts who experienced PD within 3 yrs of 1L treatment initiation. We compared clinicopathological characteristics and treatment patterns between ExRes and ConRes using Chi-square or Wilcoxon test. We analyzed median time to treatment switch due to PD (TTS-PD) – i.e., time from metastatic diagnosis to 1L treatment end due to PD - and overall survival, via the Kaplan-Meier method and with a landmark analysis at year 3 (Y3). Our primary aim was to identify predictors of exceptional response to 1L anti-HER2 therapy. Results Of 635 pts with HER2+ MBC, we identified 147 ExRes and 370 ConRes and excluded 118 pts due to follow up ≤ 3 yrs and no PD events. Median follow up was 7.1 yrs (IQR 5.5-11.0) for ExRes and 7.1 yrs (IQR 4.0-11.4) for ConRes. Median age at MBC diagnosis was 50.7 yrs (range 21.9-91.9) for ExRes and 49.8 yrs (26.9-82.3) for ConRes. ExRes presented more often with de novo MBC than ConRes (52.1 vs 30.6%, p&amp;lt; 0.0001). On metastatic samples, more ExRes than ConRes had HER2 3+ tumors by immunohistochemistry (IHC) (93.7 vs 81.0%, p=0.002), whereas the proportion of ER-positive disease was similar between the two groups (45.6 vs 53.4%, p=0.1). Most pts received (neo)adjuvant anti-HER2 agents in both groups (62.5 vs 72.7%, p=0.1). More ExRes than ConRes (55.8 vs 42.7% p=0.007) received 1L chemotherapy (CT) plus trastuzumab (H)/pertuzumab (P). Alternative 1L treatments were CT plus H (26.5 vs 25.7%), H +/- P +/- endocrine therapy (8.2 vs 10.5%), T-DM1 (2 vs 9.2%), tyrosine kinase inhibitors-based regimens (7.5 vs 10.8%). For pts with recurrent MBC, disease-free interval was longer for ExRes than ConRes (median 4.7 vs 3.4 yrs, p=0.01). Visceral involvement at MBC relapse was similar for ExRes and ConRes (78.2 vs 77.8%, p=0.9). Brain metastases at any timepoint were less frequent among ExRes than ConRes (42.9 vs 55.1%, p=0.01). Among ExRes, 70 (47.6%) pts experienced PD after Y3, with a median TTS-PD of 4.6 (4.1-5.1) yrs. In a landmark analysis at Y3, the 2-year TTS-PD was 68.5% (95% CI: 59.8%-75.7%) (5 yrs from treatment start), and 4-year overall survival was 86.5% (95% CI: 78.1%-91.9%) (7 yrs from treatment start). ConRes received a median of 5 (1-19) treatment regimens for MBC, with a median 1L TTS-PD of 12 (10.8-13) mo. A total of 89 (60.5%) ExRes and 214 (57.8%) ConRes underwent tumor sequencing. Data comparing genomic features between ExRes and ConRes will be presented. Conclusions In this prospective cohort, 28% of pts with HER2+ MBC had exceptional response to 1L anti-HER2 therapy. Consistent with prior data, ExRes present more frequently with de novo disease and HER2 IHC 3+ tumors. In our cohort, ExRes had a median follow-up of 7.1 years and 52.4% never experienced PD. Although a significant proportion of pts with HER2+ MBC derive long-term benefit from anti-HER2 therapy, the treatment paradigm remains palliative, and it is unknown whether biomarkers may reliably predict exceptional response and guide future treatment. Ongoing work will explore whether genomic features vary between ExRes and ConRes. Citation Format: Stefania Morganti, Tianyu Li, Katheryn Santos, Melissa Hughes, Nolan Priedigkeit, Yvonne Li, Marla Lipsyc-Sharf, Gregory Kirkner, Janet Files, Julie Kasparian, Elizabeth Grant, Gunjan Gupta, Giuseppe Curigliano, Sara Tolaney, Andrew Cherniack, Nabihah Tayob, Nancy Lin, Heather Parsons. Predictors of exceptional response to first line HER2-targeted therapy for metastatic 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 PO2-04-01.

Abstract PS09-06: Tumor infiltrating lymphocytes as a predictor of pathologic complete response to neoadjuvant therapy in HER2 positive breast cancer

Abstract Background The presence of tumor infiltrating lymphocytes (TILs) has shown positive prognostic relevance for certain subtypes of breast cancer, although its value as a predictive biomarker is still uncertain. The purpose of this study was to study the association between TILs expression with the pathologic complete response (pCR) following neoadjuvant therapy in Mexican patients with HER2+ breast cancer. Methods Retrospective cohort of patients with stage I-III HER2+ breast cancer who received neoadjuvant therapy between 2017 and 2020 at Instituto Nacional de Cancerología (INCan). We collected demographic and clinico-pathological characteristics. Stage was assigned using AJCC 7th criteria; hormone receptor (HR) and HER2 status were determined according to ASCO-CAP guidelines. Quantification of TILs was made by microscopy and stained with hematoxylin-eosin. TIL levels were defined as low (1-10%) intermediate (11-40%) and high ( &amp;gt;40%). Complete pathologic response was defined as the absence of invasive disease in breast and axilla (ypT0/is N0). pCR rates were compared using X2 and Fisher's exact tests according to demographic and clinicopathologic characteristics. Univariate logistic regression analysis was performed to estimate the probability of pCR according to relevant characteristics. Those parameters with p ≤0.10 on univariate analysis were included in a multivariate logistic regression model. A p&amp;lt; 0.05 was considered as statistically significant. Results We included 164 patients (mean age 51.0 years, SD 11.4). 86 patients (54.1%) were postmenopausal, 75 patients (47.2%) had T3-T4 tumors, 129 patients (81.1%) had positive lymph nodes, 133 patients (83.6%) presented Ki67 ≥30%, 59 patients (37.1%) had negative hormone receptors, 136 patients (85.5%) were treated with anthracyclines and 20 patients (12.6%) received dual anti-HER2 therapy with trastuzumab/pertuzumab. TIL expression was low in 84 patients (52.8%), intermediate in 47 (29.6%), and high in 28 patients (17.6%). The pathologic complete response (pCR) rate in the overall population was 50.9%. pCR rates according to the demographic and clinico-pathological features are listed in Table 1. In patients with intermediate-high TILs, pCR rates were 73.1% with trastuzumab, and 75.0% with dual HER2 blockade (p=0.91). Among patients with low TILs, pCR rates were 23.6% and 75.0%, respectively (p &amp;lt; 0.001). On univariate analysis, intermediate TILs (OR 3.59; 95% C.I 1.70-7.59; p= &amp;lt; 0.001), high TILs (OR 29.00; 95% C.I 6.40-131.37; p= &amp;lt; 0.001), Ki67 ≥30% (OR 2.73, 95% C.I 1.11-6.73; p=0.02), and dual anti-HER2 therapy (OR 3.31; 95% C.I 1.14-9.63 p= 0.021) were associated with a higher probability of pCR. T3/T4 tumor size (OR 0.43; 95% C.I 0.22-0.81; p = 0.009) was associated with a lower probability of pCR. Positive lymph nodes, HR status , and use of anthracyclines were not significantly associated. On multivariate analysis, intermediate TILs (OR 3.28; 95% C.I 1.46-7.32 p=.004), high TILs (OR 32.37; 95% C.I 6.84-153.04 p= &amp;lt; 0.001), and dual anti-HER2 therapy (OR 6.58; 95% CI 2.01-21.47 p= .002) remained significantly associated with pCR. Conclusions Intermediate/high TIL expression was significantly associated with pCR. Our results suggest that TIL expression could help select patients with locally advanced HER2+ breast cancer for treatment intensification with dual HER2 blockade in resource-limited settings. However, these findings require confirmation in larger, prospective studies before implementation into routine practice. TABLE 1. Pathologic complete response (pCR) rates according to demographic and clinical pathological features (n=164). Citation Format: Alberto Monroy Chargoy, Haydee Cristina Verduzco-Aguirre, Javier Monroy Chargoy, Jose Rodrigo Espinosa-Fernandez, Jesus Antonio Martinez Ojeda, Paula Cabrera-Galeana. Tumor infiltrating lymphocytes as a predictor of pathologic complete response to neoadjuvant therapy in HER2 positive 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 PS09-06.

Abstract PO2-07-06: Multimodal learning predictor of HER2-positive breast cancer therapy response in the randomized PREDIX HER2 trial

Abstract Background: The PREDIX HER2 trial, compared six courses of docetaxel, trastuzumab, and pertuzumab (DTP) vs. trastuzumab emtansine (T-DM1) as neoadjuvant treatment for HER2-positive breast cancer (BC). Similar rates of pathologic complete response (pCR) were seen. Methods: Clinicopathological, shallow whole-genome sequencing (CUTseq, n=176), whole exome sequencing (WES, n=192), and RNA-sequencing (RNA-seq, n=187) data were generated using fresh-frozen baseline core biopsies. Potential tumor intrinsic resistance factors and microenvironment components were quantified by multi-omics analysis, including BC-specific somatic mutations and copy number alterations (CNA), COSMIC mutational signatures, CNA-based chromosomal instability signatures (CIN), subclone percentage, PAM50 subtype, GGI/PIK3CA score, HER2DX score, immune profiles (Danaher signature score, TIDE score and immune repertoires). We assessed the association of biomarkers with pCR in each treatment arm using logistic regression adjusting for hormone receptor (HR) status, and evaluated their predictive value by adding the interaction term (biomarker x treatment arm). In addition, a machine learning (ML) analysis was conducted from different classifiers, comprising unimodal ML-based models from clinical, RNA and DNA information, respectively. Model performance was assessed using the mean and standard deviation (mean ± std) of the area under receiver operator characteristic curve (AUC), positive predictive value (PPV) and negative predictive value (NPV) using a nested stratified cross-validation (CV) schema of 200 outer shuffle splits and 100 inner 5-fold CV to mitigate potential risk of overfitting. Results: In DTP arm, patients with higher ERBB2 copy ratio (ORadj=1.98, p=0.004) or mRNA (ORadj=3.08, p&amp;lt; 0.001) or HER2-enriched subtype (PAM50) (ORadj=1.78, p=0.02) had higher pCR rates, while ESR1 gene expression (ORadj=0.59, p=0.07) predicted treatment resistance despite adjustment for HR status. Conversely, response to T-DM1 was less likely to depend on ERBB2 profiles and only PAM50 HER2 enriched subtype (ORadj=1.53, p=0.1) showed higher pCR rate (52% vs. 25%) than other subtypes. Both ESR1 (ORadj=0.4, p=0.008) and PGR (ORadj=0.5, p=0.03) gene expression were independent predictors of T-DM1 resistance. Pre-treatment immune exclusion metrics could predict resistance to DTP (endothelial cell, ORadj=0.67, p=0.07) and T-DM1 (neutrophils, ORadj=0.54, p=0.02; mast cells, ORadj=0.57, p=0.02; cancer-associated fibroblasts, ORadj=0.67, p=0.09)), respectively. Predefined metrics such as PIK3CA signature score (ORadj =1.67, p=0.04) and Taxane response score (ORadj =1.64, p=0.03) were positively related to pCR in DTP arm. Genome instability, involving CIN CX2 signature (impaired homologous recombination) (ORadj=1.71, p=0.05), COSMIC signature6 (ORadj =1.53, p=0.07) and signature13 (ORadj =1.57, p=0.05), predicted benefit from DTP. The biomarker-treatment interaction tests were significant for HER2DX (pinteraction=0.004) and COSMIC signature15 (defective DNA mismatch repair) (pinteraction=0.007): lower HERDX score (ORadj =0.73, p=0.14) or higher COSMIC signature15 score (ORadj =1.51, p=0.1) could identify patients benefiting from T-DM1, while being resistant to DTP (HERDX: ORadj =1.46, p=0.13; signature15: ORadj =0.70, p=0.1). In the ML models, clinical information yielded an AUC=0.62±0.07, PPV=0.64±0.12 and NPV=0.64±0.06; for DNA data, AUC was equal to 0.70±0.08, PPV=0.72±0.09 and NPV=0.71±0.07; an adaptive boosting ensemble learning on RNA reported slightly increased pCR prediction performance (AUC=0.72±0.06, PPV=0.64±0.06, NPV=0.80±0.09). Conclusion: This study demonstrates that antibody–drug conjugates and standard treatment harbor strikingly distinctive biomarkers across tumor ecosystem. Further external validation and integrated ML model comprising all unimodal models are ongoing. Citation Format: Kang Wang, Yajing Zhu, Ioannis Zerdes, Emmanouil Sifakis, Georgios Manikis, Dimitrios Salgkamis, Nikolaos Tsiknakis, Luuk Harbers, Nicola Crosetto, Jonas Bergh, Alexios Matikas, Thomas Hatschek, Theodoros Foukakis. Multimodal learning predictor of HER2-positive breast cancer therapy response in the randomized PREDIX HER2 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 PO2-07-06.

Abstract PO1-15-05: Gene expression signature as a predictor of pathological complete response to neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab treatment in locally advanced HER2-positive breast cancer

Abstract Background: Neoadjuvant pertuzumab and trastuzumab in combination with chemotherapy can achieve pathological complete response (pCR, defined as ypT0/is ypN0) in approximately 40–60% of patients with human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC). Patients who achieve pCR have significantly improved survival. Therefore, the prediction of pCR is crucial for optimizing neoadjuvant therapy. Methods: To identify a gene expression signature that could predict pCR in patients with HER2+ BC, we used the nCounter Breast Cancer 360TM V2 panel to quantify the expression of 758 genes in 104 HER2+ BC samples from patients who received neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) chemotherapy and subsequent curative breast surgery. Data normalization, differentially expressed gene (DEG) analysis, and gene set enrichment analysis (GSEA) were performed using the NanoTube Bioconductor package. Using the elastic net logistic regression model with optimal hyperparameters determined by 5-fold cross-validation (5-CV), we developed a chemosensitivity score based on the expression of significant DEGs (genes with absolute log2-fold-change ≥0.5 and q-value &amp;lt; 0.1). We tested its predictive value for pCR using multivariable logistic regression analysis. Results: The median age at diagnosis was 49.5 years. The clinical stage was II in 53 (51%) patients and III in 51 (49%) patients at diagnosis. Ninety (86.5%) patients had a HER2 immunohistochemistry (IHC) score of 3+, while the remaining 14 (13.5%) patients had HER2 IHC 2+ but HER2 amplification detected by in situ hybridization. Pathological evaluation of surgical specimens revealed that 55 (52.9%) patients achieved pCR. Menopausal status (p = 0.01), PAM50 intrinsic subtype (p = 0.002), hormone receptor (HR) status (p &amp;lt; 0.001), and HER2 IHC score (p = 0.019) were significantly correlated with the pCR rate. DEG analysis using the PAM50 intrinsic subtype, HR status, and HER2 IHC score as covariates revealed 6 downregulated DEGs and 33 upregulated DEGs in patients who achieved pCR compared to patients who did not (Table 1). The 39 DEGs were significantly enriched in nine preselected MSigDB hallmark gene sets representing immunological processes (p &amp;lt; 0.001). The optimal elastic net logistic regression model containing 39 DEGs achieved the mean 5-CV area under the receiver operating characteristic curve of 0.81. The chemosensitivity score calculated using the optimal model parameters was significantly correlated with pCR after adjustment for the PAM50 intrinsic subtype, HR status, and HER2 IHC score (p &amp;lt; 0.001). GSEA revealed eight hallmark gene sets that were significantly up- or downregulated in samples with pCR, including epithelial-mesenchymal transition (normalized enrichment score [NES] = -2.16; q &amp;lt; 0.001), late estrogen response (NES = -2.01; q = 0.004), early estrogen response (NES = -1.972; q = 0.005), and inflammatory response (NES = 1.53; q = 0.06). Conclusion: Our findings demonstrate that gene expression patterns can predict the response to neoadjuvant TCHP chemotherapy in HER2+ BC. The functional characterization of 39 DEGs suggests that the tumor microenvironment, including adjacent immune cells, plays a significant role in modulating the response to neoadjuvant chemotherapy in HER2+ BC. Table 1. Significant DEGs Citation Format: Junghoon Shin, Ji-Yeon Kim, Eun Yoon Cho, Seok Won Kim, Jeong Eon Lee, Hyunwoo Lee, Yeon Hee Park, Jin Seok Ahn, Young-Hyuck Im. Gene expression signature as a predictor of pathological complete response to neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab treatment in locally advanced HER2-positive 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 PO1-15-05.

Abstract PO5-01-04: HER2 Amplification Level and Focal/Broad Region Size as Predictors of Treatment Response in Neoadjuvant Chemotherapy and Anti-HER2 Therapy for HER2-Positive Breast Cancer

Abstract Background: Neoadjuvant chemotherapy combined with anti-HER2 therapy has become the standard treatment approach for HER2-positive breast cancer. However, not all HER2-positive patients can achieve pathological complete response after neoadjuvant therapy. This raises the question of which subset of HER2+ patients derive the greatest benefit from pre-operative HER2-targeted treatment. Therefore, this study aims to determine whether the level and amplification region size of HER2 amplification are associated with the efficacy of neoadjuvant chemotherapy combined with anti-HER2 therapy. Methods: A total of 523 breast cancer samples were collected from 2017 to 2018, among which 202 cases were HER2-positive patients. Among these, 55 HER2-positive patients received neoadjuvant chemotherapy combined with anti-HER2 targeted therapy. The amplification status of HER2 was assessed using immunohistochemistry/fluorescence in situ hybridization (IHC/FISH) and next-generation sequencing (NGS). The HER2/CEP17 ratio, determined by FISH, was used to represent the amplification level of HER2. The size of the amplification region was calculated using NGS and neighboring genes located in chr17q. Amplification regions smaller than 1 Mb were classified as focal amplification, while those larger than 1 Mb were classified as broad amplification. Results: We compared the HER2/ERBB2 status of 523 breast cancer patients using different detection methods and found a high concordance between ERBB2 amplification detected by NGS and HER2-positivity detected by IHC and FISH, with a sensitivity of 96.0%, specificity of 97.8%, and overall concordance of 97.1%. Based on the HER2/CEP17 ratio determined by FISH, we observed that using a threshold of 6 for classification, the high amplification group had a significantly higher pCR rate compared to the low amplification group (86.7% vs. 41.7%; p=0.037, odds ratio [OR]=0.121, 95% confidence interval [CI]: 0.009-0.919). Moreover, the focal amplification group showed a higher pCR rate compared to the broad amplification group (65.9% vs. 30.8%, p=0.051, OR=0.237, 95% CI: 0.045-1.035). Additionally, within the low amplification group (HER2/CEP17 &amp;lt; 6), the pCR rate was 66.7% for focal amplification and 20% for broad amplification, suggesting that focal amplification of ERBB2 may further guide clinical benefit in the low HER2/CEP17 ratio group. Conclusion: This study demonstrates a high concordance between ERBB2 amplification determined by NGS and HER2-positivity determined by IHC/FISH. High HER2/CEP17 ratio and focal amplification of ERBB2 are associated with a higher pCR rate in neoadjuvant chemotherapy combined with anti-HER2 targeted therapy. Citation Format: Ning Liao, Guochun Zhang, Xinze Lv, Kai Li, Ting Hou, Zhou Zhang. HER2 Amplification Level and Focal/Broad Region Size as Predictors of Treatment Response in Neoadjuvant Chemotherapy and Anti-HER2 Therapy for HER2-Positive 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 PO5-01-04.

Abstract PO1-27-06: HER2 Amplification Level and Focal/Broad Region Size as Predictors of Treatment Response in Neoadjuvant Chemotherapy and Anti-HER2 Therapy for HER2-Positive Breast Cancer

Abstract Background: Neoadjuvant chemotherapy combined with anti-HER2 therapy has become the standard treatment approach for HER2-positive breast cancer. However, not all HER2-positive patients can achieve pathological complete response after neoadjuvant therapy. This raises the question of which subset of HER2+ patients derive the greatest benefit from pre-operative HER2-targeted treatment. Therefore, this study aims to determine whether the level and amplification region size of HER2 amplification are associated with the efficacy of neoadjuvant chemotherapy combined with anti-HER2 therapy. Methods: A total of 523 breast cancer samples were collected from 2017 to 2018, among which 202 cases were HER2-positive patients. Among these, 55 HER2-positive patients received neoadjuvant chemotherapy combined with anti-HER2 targeted therapy. The amplification status of HER2 was assessed using immunohistochemistry/fluorescence in situ hybridization (IHC/FISH) and next-generation sequencing (NGS). The HER2/CEP17 ratio, determined by FISH, was used to represent the amplification level of HER2. The size of the amplification region was calculated using NGS and neighboring genes located in chr17q. Amplification regions smaller than 1 Mb were classified as focal amplification, while those larger than 1 Mb were classified as broad amplification.&amp;gt; Results: We compared the HER2/ERBB2 status of 523 breast cancer patients using different detection methods and found a high concordance between ERBB2 amplification detected by NGS and HER2-positivity detected by IHC and FISH, with a sensitivity of 96.0%, specificity of 97.8%, and overall concordance of 97.1%. Based on the HER2/CEP17 ratio determined by FISH, we observed that using a threshold of 6 for classification, the high amplification group had a significantly higher pCR rate compared to the low amplification group (86.7% vs. 41.7%; p=0.037, odds ratio [OR]=0.121, 95% confidence interval [CI]: 0.009-0.919). Moreover, the focal amplification group showed a higher pCR rate compared to the broad amplification group (65.9% vs. 30.8%, p=0.051, OR=0.237, 95% CI: 0.045-1.035). Additionally, within the low amplification group (HER2/CEP17 &amp;lt; 6), the pCR rate was 66.7% for focal amplification and 20% for broad amplification, suggesting that focal amplification of ERBB2 may further guide clinical benefit in the low HER2/CEP17 ratio group. Conclusion: This study demonstrates a high concordance between ERBB2 amplification determined by NGS and HER2-positivity determined by IHC/FISH. High HER2/CEP17 ratio and focal amplification of ERBB2 are associated with a higher pCR rate in neoadjuvant chemotherapy combined with anti-HER2 targeted therapy. Citation Format: Ning Liao, Guochun Zhang, Xinze Lv, Kai Li, Ting Hou, Zhou Zhang. HER2 Amplification Level and Focal/Broad Region Size as Predictors of Treatment Response in Neoadjuvant Chemotherapy and Anti-HER2 Therapy for HER2-Positive 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 PO1-27-06.

Abstract PO4-17-06: Real World Data: A single institute experience with neoadjuvant endocrine therapy for ER+ breast cancer — clinical response rates, clinical predictors of response and long-term outcomes following breast conserving surgery

Abstract Background: Neoadjuvant endocrine therapy (NET) in postmenopausal women (PMW) with large or locally advanced oestrogen receptor (ER)-rich breast cancer allows more women to be treated by breast-conserving surgery (BCS). A comprehensive analysis of the factors affecting clinical response to NET and the long-term safety of this strategy has been studied. Patients: A retrospective cohort was studied of 435 PMW (median age: 77 years; range: 50-98) with ER-positive breast cancer treated with NET (aromatase inhibition) (median duration: 6.8 months; range 3-43 months), between 2001-15. Clinical response was monitored throughout NET treatment with periodic 3D ultrasound measurements of the primary tumour. All patients went on to have surgery, 55% had adjuvant radiotherapy and all had adjuvant ET for at least 5 years. All patients had routine follow-up (median follow-up 12.3 years). To-date, this represents the largest cohort of patients treated with &amp;gt;3 months NET. Results: Clinical response to NET was excellent, with only 3.2% of tumours progressing on-treatment based on RECIST 1.1 criteria. Mean percentage reduction in tumour on NET was 71%. Response rate (partial/complete response) was 59% and response continued until 12 months and then levelled off. Following NET, over 92% of patients were suitable for BCS and 61% achieved clinical TNM down-staging. Multivariate analysis revealed that only ER level (response highest in patients with Allred scores 7 and 8), and percentage change in tumour volume by 6 weeks were significant predictors of overall clinical response to NET. Clinical response to NET was not associated with node status or tumour grade. BCS following NET had a local disease control rate of 89% (95%CI±0.06) at 10 years, but actuarial local recurrence at 10 years was only 7% in those having radiotherapy compared with 30% in the group who did not receive radiotherapy (P&amp;lt; 0.0001). In addition, the overall recurrence rate (P=0.028) was improved by radiotherapy irrespective of nodal status. Radiotherapy did not improve overall breast cancer-specific survival (BCSS). Systemic recurrence and BCSS was higher with greater nodal involvement. Most patients in this study died of other causes (14-year crude all-cause mortality was 71%). Conclusion: NET followed by BCS is an effective strategy in PMW with ER-rich breast cancer. Excellent clinical response rates are seen even in women with node-positive or high-grade disease. Less than 5% showed evidence of progression. Early response to NET predicts for long-term tumour volume reduction and NET can achieve continued tumour shrinkage for up to 1 year. NET followed by BCS appears a safe treatment approach and offers good long-term outcomes when BCS is followed by adjuvant radiotherapy. Citation Format: Arran K Turnbull, Carlos Martinez-Perez, Charlene Kay, Rebecca Swan, Lorna Renshaw, J Michael Dixon. Real World Data: A single institute experience with neoadjuvant endocrine therapy for ER+ breast cancer — clinical response rates, clinical predictors of response and long-term outcomes following breast conserving surgery [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 PO4-17-06.

Abstract PO1-06-09: Phase 2 Trial with Safety Run-In of Gedatolisib Plus Talazoparib in Advanced Triple Negative or BRCA1/2 Positive, HER2 Negative Breast CancersBig Ten Cancer Research Consortium BTCRC-BRE18-337

Abstract Up to 2/3 of triple negative breast cancers (TNBC) have acquired defects in homologous recombination (HR) DNA repair, yet poly (ADP-ribose) polymerase inhibitor (PARPi) monotherapy has been largely ineffective in the absence of a germline BRCA 1/2 mutation (gBRCA1/2). Phosphoinositide-3-kinase (PI3K)/mTOR pathway alterations are also common in breast cancers. Preclinical data suggest that PI3K/mTOR inhibition may disrupt normal function of the HR complex and increase dependency on PARP enzymes for HR DNA repair. Thus, combining a PI3K/mTOR inhibitor with a PARPi may result in a synergistic anti-neoplastic effect. The run-in portion of this study evaluated the safety of weekly IV gedatolisib (PI3K/mTORi) and continuous daily talazoparib to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). A 3+3 design for dose escalation explored two dose levels. The phase II study began once the MTD and R2PD were confirmed. Eligibility required age ≥ 18, 1-2 prior lines of therapy (protocol later amended to allow up to 3 lines), and advanced TNBC or advanced HER2-negative BC with gBRCA1/2 mutation. The sample size for the phase II study was determined based on a 1-sided binomial test under the null and alternative ORR of 5% vs 20% with a type I error rate of 0.1 and power level of 80%. The primary endpoint was overall response rate (ORR) in TNBC without known gBRCA1/2 with secondary endpoints of progression-free survival (PFS) and overall survival (OS). Patients with a gBRCA1/2 mutation were not included in the primary endpoint analysis. Correlative studies are planned to evaluate HR deficiency mutations, PIK3CA mutations, and other exploratory genomics. A total of 33 patients were enrolled: 14 in the safety run-in phase of the trial and 19 in the phase II study (17 TNBC, 2 with gBRCA2 mutation). In the safety run-in, 6 patients were enrolled at dose level 1 (0.75 mg talazoparib po daily and 180 mg gedatolisib IV weekly) and 8 at dose level 2 (1 mg talazoparib po daily and 180 mg gedatolisib IV weekly). 42% of the cohort developed hyperglycemia, which was mostly grade 1. There was 1 DLT of grade 3 neutropenia at dose level 1. There were 3 patients who experienced grade 4 AEs, thrombocytopenia (2) and lymphopenia (1) which were outside of the DLT window. The MTD was 1 mg of talazoparib daily and 180 mg of gedatolisib weekly, and this was selected as the RP2D. A protocol amendment was made during the phase II portion to allow for a 3 week on/1 week off schedule for gedatolisib due to emerging data showing a more favorable safety profile and enhanced antitumor activity with this dosing schedule. In the 17 patients with TNBC and no gBRCA mutation in the phase II cohort, the ORR was 12%. Best response was partial response (PR) in 2 patients (12%), stable disease (SD) in 7 patients (41%), and progressive disease (PD) in 8 patients (47%). The clinical benefit rate (ORR+SD) at 16 weeks was 23.5%. The most common adverse events (AEs) in all 33 patients were anemia (70%), fatigue (67%), oral mucositis (64%), nausea (60%), neutropenia (45%) and anorexia (45%). Of these, most were grade 1-2 other than anemia (35% grade 3), neutropenia (20% grade 3), fatigue (18% grade 3), and oral mucositis (10% grade 3). There were no grade 4 AEs in the phase II study. Median PFS was approximately 3 months and median OS was approximately 6.4 months. Although this study did not meet its primary endpoint, there were 2 TNBC patients without a gBRCA1/2 mutation who achieved a partial response to this non-chemotherapy regimen. Future biomarker testing may help elucidate these findings and possible predictors of response. Citation Format: Sneha Phadke, Kari Wisinski, Oana Danciu, Ami Shah, Menggang Yu, Yi Chen, Kathy Miller, Mark Burkard. Phase 2 Trial with Safety Run-In of Gedatolisib Plus Talazoparib in Advanced Triple Negative or BRCA1/2 Positive, HER2 Negative Breast CancersBig Ten Cancer Research Consortium BTCRC-BRE18-337 [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 PO1-06-09.

Abstract PO5-05-01: ASSESING THE CLINICAL AND SURVIVAL RESULTS OF PATIENTS WITH HR-POSITIVE, HER2 NEGATIVE ADVANCED BREAST CANCER TREATED WITH CDK 4/6 INHIBITORS IN A SPANISH COHORT

Abstract BACKGROUND First line treatment of HR-positive, HER2 negative advanced breast cancer is based on endocrine therapy plus CDK 4/6 inhibitors (CDK 4/6i). Recently, there has been published in ASCO 2023 results from SONIA trial, which explores the use of CDK 4/6i in second-line treatment after monotherapy with endocrine therapy. This trial have shown using a CDK4/6i in the first-line setting did not significantly prolong the time from random assignment to progression on second-line therapy (PFS2) or overall survival (OS) when compared with deferred use until the second-line setting. METHODS We conducted a descriptive, observational and retrospective analyses of patients treated in our centre with CDK4/6i, comparing demographic, clinical and survival results. We also analysed different outcomes between first versus second line CDK4/6i. RESULTS A cohort of 153 patients were included, treated between January 2018 and June 2023, with a median age of 50 years. At diagnosis, 49% were stage I-II and 31% stage IV. 59% had visceral metastases at the start of CDK4/6i treatment. Palbociclib was the most commonly CDK4/6i used (55%), followed by Ribociclib (32%) and Abemaciclib (12.5%). The most widely endocrine therapy used was letrozole (60%), followed by fulvestrant (38%). 58% received CDK4/6i in first-line setting while 9% received them in second-line. The overall median progression-free survival (mPFS) was 18 months. In a subgroup analysis, the mPFS was 19 months with Palbociclib, 26 months with Ribociclib, and 31 months with Abemaciclib. Baseline characteristics were similar between subgroups of CDK4/6i. Better survival data were obtained with letrozole than with fulvestrant (not reached versus 29 months OS respectively). After CDK4/6i disease progression the most common subsequent treatment was chemotherapy (capecitabine, 23%). The median OS with palbociclib and abemaciclib was 37 months, while not reached with ribociclib. We analysed PFS2 using CDK4/6i in the first-line setting compared with deferred use until the second-line. The use of CDK4/6i in second-line showed a PFS2 of 45 months, while first-line PFS2 was 26 months. CONCLUSIONS Our study results are consistent with previous studies assesing the efficacy of cyclin inhibitors in first and second-line setting. Palbociclib seems to have a lower PFS rate. Patients treated with letrozole had a stadistically significant benefit in survival outcomes. Our data continue the trend observed in the SONIA trial in terms of PFS2. Using endocrine therapy as first-line monotherapy may be a valid treatment option. However, larger sample sizes are required to draw definitive conclusions. The identification of potential predictors of treatment response may help in the selection of the most effective treatment for patients with HR-positive HER2 negative advanced breast cancer. Citation Format: Alicia Cano-Jimenez, Rocio Urbano-Cubero, Ruben Garcia-Muñoz, Ana Maria Jaen-Morago, Maria Lomas-Garrido, Pedro Sánchez-Rovira. ASSESING THE CLINICAL AND SURVIVAL RESULTS OF PATIENTS WITH HR-POSITIVE, HER2 NEGATIVE ADVANCED BREAST CANCER TREATED WITH CDK 4/6 INHIBITORS IN A SPANISH COHORT [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 PO5-05-01.

Abstract PO2-18-05: Blocking soluble TNF to Improve potency of trastuzumab deruxtecan by increasing internalization and antitumor innate immune response in a resistant HER2-positive breast cancer model

Abstract Background Trastuzumab deruxtecan (T-DXd) administration improves response for patients with HER2-positive metastatic breast cancer (HER2+ BC). Unfortunately, 50% of patients relapse after 2 years. T-DXd resistance mechanisms are being explored. For trastuzumab we have shown that mucin 4 (MUC4) expression is an independent predictor of poor response in HER2+BC patients. MUC4 is upregulated by soluble TNF (sTNF) secreted by the tumor, confers resistance to trastuzumab by hiding its epitope on the HER2, reducing its binding and decreasing anti-tumor phagocytic function. In preclinical models of de novo trastuzumab-resistant tumors, combination of a sTNF blocking agent INB03, (DN), with T-DXd decreases tumor growth compared to T-DXd alone. To disclose the underlying mechanism, we studied whether DN improved internalization of T-DXd in tumor cells and modified the innate immune response to enhance T-DXd antitumor effects in a multiple HER2-targeted therapy-resistant model. Methods Nude mice bearing HER2+MUC4+ JIMT-1 tumor, primary resistant to trastuzumab, pertuzumab and lapatinib, were treated with IgG 5 mg/kg, T-DXd 5 mg/kg (T-DXd 5), 2.5 mg/kg (T-DXd 2.5) or 1.25 mg/kg (T-DXd 1.25), DN 10 mg/kg or the combined therapies. T-DXd and IgG were administered i.v. on days 0, 7 and 14. DN was administered i.p. twice a week for 3 weeks. Tumor growth was monitored. Mitotic figures/field (mean) were analyzed in H&amp;E tumor sections. Tumor-infiltrating macrophages were studied by flow cytometry. IFNƔ was determined in tumor extracts by ELISA. Internalization of T-DXd in JIMT-1 cells was studied in a S1 Incucyte along 18h by Fab-rhodo red labeling. Results T-DXd dose-response curves showed inhibition in tumor growth of 83%, 61% and 37% for T-DXd 5, 2.5 and 1.25 mg/kg treatment respectively compared with IgG-treated tumors. DN alone exhibited no antitumor activity. T-DXd+DN increased the antitumor effect by 10%, 33% and 97% for T-DXd dose of 5, 2.5 and 1.25 mg/kg respectively. Tumor growth inhibition of T-DXd 5 was similar to combination of T-DXd1.25+DN. Addition of DN did not have toxicity. DN increases IFNƔ production in the TME of T-DXd treated tumors vs T-DXd alone and promoted macrophage recruitment to the tumor bed and polarization to the antitumor M1-like phenotype. Histopathological analysis of the tumor showed a significant decrease in proliferation in all the combined and in the T-DXd 5mg/kg (2.8-3.7 mitotic figures/field) vs IgG (6.0 mitotic figures/field). In vitro, JIMT-1 cells treated with DN internalized 40% more T-DXd than its vehicle-treated counterparts. Conclusions Neutralizing sTNF with DN enhances T-DXd effect in a multiple HER2 targeted therapy resistant model of MUC4 expressing HER2+ BC. Combination of DN with T-DXd increases tumor response at all dose levels tested. The largest effect was seen at lower doses (T-DXd 1.25+DN), which mimicked the effect of 4 times the dose of T-DXd alone, suggesting significant synergy with DN as dose of T-DXd decreases. Combination of DN with T-DXd in MUC4 expressing HER2+ BC improves response to T-DXd alone by increasing T-DXd internalization and improving anti-tumor innate immune responses in the TME without increasing toxicity. The results suggest this combination should be investigated in clinical trials in patients who have MUC4 expressing tumors when T-DXd is started or become resistant to T-DXd therapy. Citation Format: Sofia Bruni, Florencia Mauro, Sofia Naveiro, Rosalia Cordo-Russo, Agustina Dupont, Mercogliano María Florencia, Roxana Schillaci. Blocking soluble TNF to Improve potency of trastuzumab deruxtecan by increasing internalization and antitumor innate immune response in a resistant HER2-positive breast cancer model [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 PO2-18-05.

Abstract PO3-15-02: TP53 GENE POLYMORPHISM AT CODON 72 AS A RESPONSE PREDICTOR FOR NEOADJUVANT CHEMOTHERAPY

Abstract Introduction: Breast cancer is one of the most prevalent in women in the world and has shown extensive changes in treatment in recent decades. More patients are undergoing neoadjuvant chemotherapy in order to achieve pathological complete response (CPR) and perform less aggressive surgeries. CPR increases overall and disease-free survival and the decrease in tumor size increases the chances of conservative surgery. We have numerous studies that propose to discover CPR markers. Predictive factors of response to chemotherapy are important for treatment planning and the P53 gene, apoptosis-inducing gene, plays a role in inducing response to chemotherapy drugs that act by inducing apoptosis. The presence of mutations and genetic polymorphisms act by modulating this response. Among these, the codon 72 polymorphism is one of the most studied, as its polymorphic variants Arg/Arg, Arg/Pro and Pro/Pro encode a p53 with different functioning at the cell level. So, individuals with different polymorphisms will have different apoptotic action and different response to chemotherapy treatments. Objectives: Based on this knowledge, the study sought to correlate the polymorphism variants at codon 72 with the complete pathological response to neoadjuvant chemotherapy. Casuistic and Methods: The study was carried out at an oncology center in the state of Sergipe, in northeastern Brazil. A total of 206 patients with breast cancer who underwent neoadjuvant chemotherapy and core needle biopsy of the breast at the beginning of treatment were included in the stud,in the period from 2019 to 2022. From these patients, oral swab samples were collected for PCR evaluation of the P53 polymorphism at codon 72. The polymorphisms were studied using the Sanger technique at the Sao Paulo School of Medicine of the Federal University of São Paulo (UNIFESP). Patients were prospectively evaluated after surgery to verify the surgical pathological response after chemotherapy. Pathologic response was assessed using the RECIST criteria. The study was evaluated and approved by the ethics and research committee of UNIFESP and all patients signed an informed consent form. Results: Of the 206, 18.4% met the exclusion criteria (did not undergo surgery, interrupted chemotherapy treatment, insufficient genetic material in the swab, loss of follow-up). Of the 168 patients analyzed, 44.6% were Arg/Arg, 17.3% Pro/Pro and 38.0% Arg/Pro. Complete pathological response (PCR) was obtained in 21.4% of the patients, 10.1% had progressive disease (PD), 13.7% had stable disease (SD) and 54.2% had partial pathological response (PPR). Of the patients who achieved RPC, 47.2% were Arg/Arg, 38.9% Arg/Pro and 13.9% Pro/Pro without statistical significance, among the variants of polymorphisms. The only predictor of CPR in multivariate regression was immunohistochemistry (p&amp;lt; 0.001). The only predictor of CPR in multivariate regression was immunohistochemistry (p&amp;lt; 0.001) Conclusion: The P53 polymorphism at codon 72 is not a predictor of complete pathological response, but the Arg/Pro and Pro/Pro polymorphisms increase the chances of stable disease after neoadjuvant chemotherapy. Citation Format: Jussane Vieira, Afonso Nazário, João Pesquero. TP53 GENE POLYMORPHISM AT CODON 72 AS A RESPONSE PREDICTOR FOR NEOADJUVANT CHEMOTHERAPY [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 PO3-15-02.