566 Background: Endocrine therapy (ET) resistance (ETR) remains a primary challenge in ER+ breast cancer. Analyzing pretreatment tumor transcriptomes across trials with early response endpoints can reveal shared and specific ETR signatures. This study utilizes baseline RNA data from the Phase III ALTERNATE trial (Alliance A011106, NCT01953588; Anastrozole [A], Fulvestrant [F], or AF) and the ACOSOG Z1031B trial (NCT00824941) to identify predictors of early Ki67 response in postmenopausal ER+/HER2– patients. Methods: ETR was defined as week-4 on-treatment Ki67 >10%. Baseline gene expression from ALTERNATE was analyzed to identify differentially expressed (DE) genes (Wilcoxon test, P<0.05) and Hallmark pathways associated with ETR, both across and within individual treatment arms. Feature selection was performed using mixOmics. A Pan-Endocrine Therapy Signature (PETS) was developed by uniting DE genes identified across all three ALTERNATE arms and Z1031B. All statistical analyses were conducted in R (P<0.05). Results: Overall ETR rate in the ALTERNATE RNA-seq cohort (n=733) was 26%. ETR was associated with high Risk of Recurrence (ROR), Oncotype RS, and Mammaprint scores (calculated from RNA-seq data in research setting). In luminal tumors (n=649), ETR was linked to chr 3q13.33, 8q24.13, and 20q13.12 cytoband upregulation and 17q21, 18q23, 3p21.1, and 10q24.32 cytoband downregulation. ETR tumors showed T-cell, E2F target, and interferon-γ enrichment; sensitive tumors favored early estrogen response and muscle differentiation. At individual gene level, high MYBL2 , PIF1 , TROAP and with low HJURP predicted ETR across all samples (AUC>0.70). A deep learning model using all protein-coding genes achieved AUC 0.82 (training) and 0.79 (test) in predicting ETR. Cross-trial integration identified ETR-associated PETS, enriched for genomic instability. PETS performed comparably to established signatures and strongly correlated with MYBL2 signature (r=0.93). Top ETR predictors were MYBL2 , AURKB , and EME1 for Arm A and IL4I1 , TNFAIP6 , and ANLN for Arm AF. AF-resistant tumors were enriched for systemic lupus and RIG-I–like receptor signaling; sensitive tumors favored PI3K–AKT, EGFR TKI resistance, AMPK, and insulin signaling. Conclusions: Baseline transcriptomics identify shared and therapy-specific ETR markers. The 15-gene PETS defines a convergent resistance signature, performing similar to established signatures in predicting ETR and correlating with MYBL2. Enrichment of cell-cycle and immune pathways in resistant tumors may suggest patient stratification approach for alternative or combinatorial strategies to overcome early ETR in ER+ breast cancer. Acknowledgement: https://acknowledgments.alliancefound.org. Support: U10CA180821, U10CA180882, U24CA1. Clinical trial information: NCT01953588 .

PURPOSE:In light of evolving evidence that some patients with node-positive estrogen receptor-positive (ER+) disease may receive less benefit from chemotherapy, this study reports 12-year outcomes of the C9741 trial overall, and by the sensitivity to endocrine therapy (SET2,3) test index, a biomarker measuring endocrine transcriptional activity, to identify patients most likely to benefit from dose-dense chemotherapy. METHODS:In all, 1,973 patients were randomly assigned to dose-dense versus conventional chemotherapy. Hazard ratios (HRs) for prognosis and for predictive interaction with chemotherapy schedule were estimated from Cox models of long-term disease-free survival (DFS) and overall survival (OS). SET2,3 was tested on the 682 banked RNA samples from ER+ cancers. RESULTS:Dose-dense chemotherapy improved DFS in the overall study population by 23% (HR, 0.77 [95% CI, 0.66 to 0.90]) and OS by 20% (HR, 0.80 [95% CI, 0.67 to 0.95]); the benefits of dose-dense therapy were seen for ER+ and ER-negative subsets, without significant interaction between treatment arm and ER status. Low SET2,3 status was highly prognostic, but also predicted improved outcomes from dose-dense chemotherapy (interaction P = .0998 for DFS; 0.027 for OS), independent of menopausal status. Specifically, low endocrine transcriptional activity predicted benefit from dose-dense chemotherapy, whereas tumor burden and proliferation-driven signatures for molecular subtype classification did not. CONCLUSION:At 12-year follow-up, C9741 confirmed the sustained long-term benefit of adjuvant dose-dense chemotherapy for node-positive breast cancer. SET2,3 identified patients with ER+ breast cancer who benefited from dose-dense chemotherapy, and specifically, this benefit was predicted by low endocrine activity in the cancer, rather than tumor burden, molecular subtype, or menopausal status.

Background: Over 50,000 women in the United States will be diagnosed with ductal carcinoma in situ (DCIS) this year alone. Almost all of these diagnoses will be made in completely asymptomatic individuals with a highly variable risk of progression to invasive cancer. In some low-risk malignancies, “watchful waiting,” is offered as a treatment option. Such an approach is likely reasonable for some DCIS and could reduce the harms of treatment while helping to identify those most likely to benefit from more aggressive therapy. To date, this approach has not been tested in a clinical trial setting. Methods: The COMET study (Comparing an Operation to Monitoring, with or without Endocrine Therapy for low risk DCIS; AFT-25) is a large pragmatic randomized non-inferiority trial that compares oncologic outcomes between patients randomized to guideline concordant care (GCC; surgery +/- radiation therapy) or active monitoring (AM). The study population were women seeking treatment for DCIS at one of the Alliance Clinical Trial sites. Eligible participants were age>40 with low-intermediate grade estrogen and/or progesterone receptor positive, HER2 receptor negative (if HER2 tested) DCIS on core biopsy without microinvasive or invasive cancer. The choice for endocrine therapy was offered in both groups. Participants in the AM group had surgical intervention only upon diagnosis of invasive progression. All study endpoints were collected prospectively. Results: This is the first planned interim Intention-to-Treat (ITT) analysis of the COMET trial primary endpoints at a median follow up of XX months. We will present patient characteristics for the 997 participants who enrolled in the study and were randomized to either GCC or AM. The primary endpoint to be presented is whether the ipsilateral invasive cancer rate for AM is non-inferior to that for GCC. Characteristics of invasive cancer events in the two groups will be compared. Secondary endpoints (rates of mastectomy, radiation, chemotherapy) and survival endpoints between groups will also be presented. Conclusion: These data will provide the first randomized trial evidence of whether an active monitoring strategy is a safe alternative for women with low-risk DCIS. Longer-term data could support practice changing guidance as to how DCIS is managed and treated and will have future implications for treatment guidelines for these excellent prognosis patients. Citation Format: Eun-Sil Hwang, Terry Hyslop, Thomas Lynch, Marc D Ryser, Anna Weiss, Anna Wolf, Kelsey Norris, Meredith Witten, Lars Grimm, Stuart Schnitt, Sunil Badve, Rachel Factor, Elizabeth Frank, Deborah Collyar, Desiree Basila, Donna Pinto, Mark A Watson, Robert West, Louise Davies, Jenny Donovan, Ayako Shimada, Yutong Li, Yan Li, Antonia V Bennett, Shoshana Rosenberg, Jeff Marks, Eric Winer, Marc Boisvert, Armando Giuliano, Kelsey Larson, Kathleen Yost, Priscilla McAuliffe, Lisa Carey, Alastair Thompson, Ann H Partridge. Early Oncologic Outcomes Following Active Monitoring or Surgery (+/- Radiation) for Low Risk DCIS: the Comparing an Operation to Monitoring, with or without Endocrine Therapy (COMET) Study (AFT-25) [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr GS2-05.

Deep learning models applied to digital histology can predict gene expression signatures (GES) and offer a low-cost, rapidly available alternative to molecular testing at the time of diagnosis. We optimized transformer-based models to infer GES results and applied this approach to pre-treatment H&E-stained biopsies from 1,940 breast cancer patients treated with neoadjuvant chemotherapy in clinical trial and real-world cohorts. The most predictive histology-derived GES for pathologic complete response (pCR) in the I-SPY2 trial was validated in four external cohorts: CALGB 40601, CALGB 40603, a trial of durvalumab plus CT, and standard-of-care CT-treated patients from the University of Chicago. Among HER2-negative patients, a transformer-based model trained using a signature composed of estrogen-regulated genes, proliferation, apoptosis, and interferon response genes predicted pCR with an AUC of 0.794, outperforming models based on clinical features alone (AUC 0.704, p = 0.001), pathologist TIL assessment, and a model trained directly to predict response from I-SPY2 cases. Tertiles of this signature stratify patients into clinically relevant groups with increasing likelihood of complete response, with pCR rates ≥50% in the top tertile regardless of treatment or hormone receptor status. Additional transformer-based signature models predicted response to specific therapies (but not chemotherapy alone), including a HER2 signaling signature in IO-treated patients, and a claudin-low signature in bevacizumab treated patients. In HER2- cohorts with available gene expression data and histology, models trained on expression data performed similarly to digital histology predictions, but the combination of gene expression and histology outperformed histology alone. These findings suggest that histology-based GES provides additive information to RNA sequencing data and can inform precision treatment selection across breast cancer subtypes.

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Importance: Active monitoring for low-risk ductal carcinoma in situ (DCIS) of the breast has been proposed as an alternative to guideline-concordant care, but the safety of this approach is unknown. Objective: To compare rates of invasive cancer in patients with low-risk DCIS receiving active monitoring vs guideline-concordant care. Design, setting, and participants: Prospective, randomized noninferiority trial enrolling 995 women aged 40 years or older with a new diagnosis of hormone receptor-positive grade 1 or grade 2 DCIS without invasive cancer at 100 US Alliance Cancer Cooperative Group clinical trial sites from 2017 to 2023. Interventions: Participants were randomized to receive active monitoring (follow-up every 6 months with breast imaging and physical examination; n = 484) or guideline-concordant care (surgery with or without radiation therapy; n = 473). Main outcomes and measures: The primary outcome was 2-year cumulative risk of ipsilateral invasive cancer diagnosis, according to planned intention-to-treat and per-protocol analyses, with a noninferiority bound of 0.05%. Results: The median age of the 957 participants analyzed was 63.6 (95% CI, 55.5-70.5) years in the guideline-concordant care group and 63.7 (95% CI, 60.0-71.6) years in the active monitoring group. Overall, 15.7% of participants were Black and 75.0% were White. In this prespecified primary analysis, median follow-up was 36.9 months; 346 patients had surgery for DCIS, 264 in the guideline-concordant care group and 82 in the active monitoring group. Forty-six women were diagnosed with invasive cancer, 19 in the active monitoring group and 27 in the guideline-concordant care group. The 2-year Kaplan-Meier cumulative rate of ipsilateral invasive cancer was 4.2% in the active monitoring group vs 5.9% in the guideline-concordant care group, a difference of -1.7% (upper limit of the 95% CI, 0.95%), indicating that active monitoring is not inferior to guideline-concordant care. Invasive tumor characteristics did not differ significantly between groups. Conclusions and relevance: Women with low-risk DCIS randomized to active monitoring did not have a higher rate of invasive cancer in the same breast at 2 years compared with those randomized to guideline-concordant care.

Deep learning-assisted digital pathology has demonstrated the potential to profoundly impact clinical practice, even surpassing human pathologists in performance. However, as deep neural network (DNN) architectures grow in size and complexity, their explainability decreases, posing challenges in interpreting pathology features for broader clinical insights into physiological diseases. To better assess the interpretability of digital microscopic images and guide future microscopic system design, we developed a novel method to study the predictive feature length-scale that underpins a DNN's predictive power. We applied this method to analyze a DNN's capability in predicting brain metastasis from early-stage non-small-cell lung cancer biopsy slides. This study quantifies DNN's attention for brain metastasis prediction, targeting features at both the cellular scale and tissue scale in H&E-stained histological whole slide images. At the cellular scale, the predictive power of DNNs progressively increases with higher resolution and significantly decreases when the resolvable feature length exceeds 5 microns. Additionally, DNN uses more macro-scale features associated with tissue architecture and is optimized when assessing visual fields greater than 41 microns. Our study computes the length-scale requirements for optimal DNN learning on digital whole-slide microscopic images, holding the promise to guide future optical microscope designs in pathology applications and facilitating downstream deep learning analysis.

Association of stromal tumor-infiltrating lymphocytes (sTILs) with survival outcomes among patients with metastatic breast cancer (MBC) remains unclear. The primary objective was to evaluate the association of sTILs with progression-free survival in randomized phase III trial CALGB 40502. sTILs were associated with progression-free and overall survival in chemotherapy-treated MBC when controlling for treatment arm; however, this effect did not remain significant after additional adjustment for hormone receptor status. CALGB is now part of the Alliance for Clinical Trials in Oncology. Trial Registration: ClinicalTrials.gov: NCT00785291.

Abstract Background. The phase 3 PALLAS trial (NCT02513394) compared two years of the CDK4/6 inhibitor palbociclib with endocrine therapy of provider choice, versus endocrine therapy alone, as adjuvant treatment for patients with Stage II-III hormone receptor-positive HER2-negative (HR+/HER2-) breast cancer. Genomic subtype (PAM50 intrinsic subtype) measured from whole-transcriptome RNA sequencing data was defined in the protocol of the PALLAS trial as the primary biomarker for analysis of prediction and prognosis. Clinical data have been previously presented (Gnant et al, JCO 2022), and the trial now has 5-year median follow-up. Methods. As part of trial eligibility, all participants in PALLAS provided a tumor tissue block prior to randomization (surgical if primary resection, core biopsy if neoadjuvant treatment) for translational analyses (TRANS-PALLAS). The biorepository and laboratory were blinded to identity and processed samples in random order, to minimize bias. Nucleic acids were extracted from samples with sufficient tumor tissue and cellularity (>25 mm2 with ≥20% cancer nuclei). The Genome Sequencing Center at Washington University St. Louis performed whole-transcriptome RNA sequencing. Libraries were prepared from 1 µg DNase-1 treated total RNA, if total RNA DV200 >28 (Agilent Bioanalyzer), using an unbiased library protocol of RNA HyperPrep kit with RiboErase (HMR) (Kapa Biosystems, Wilmington, MA). 100 bp paired-end sequencing was performed on NovaSeq 6000 using S4 Reagent Kit (Illumina, San Diego, CA), with 48 libraries pooled per lane. Intrinsic subtype was determined using Bioclassifier package (Research PAM50 script, Parker et al.) only for the analysis population of primary breast cancer samples that had not been exposed to prior neoadjuvant therapy. Invasive disease-free survival (IDFS) will be visualized using Kaplan-Meier plots, with log-rank test between groups. Cox models of proportional hazards will be developed to evaluate prognosis adjusted for known clinical covariates, or for predictive interactions. The pre-defined level of significance is a two-sided 0.05. Results. From the total study population of 5796 enrolled patients, 4655 tissue blocks had sufficient tumor content to process for RNA, with 3931 yielding sufficient RNA for sequencing, and 2669/4655 (57.3%) submitted tissue blocks had DV200 ≥28 and were successfully sequenced. Clinical unblinding revealed 2370 unique patients (1182 in the palbociclib treatment arm and 1188 in the control arm) with intrinsic subtype defined from their untreated primary tumor: 1555 (65.6%) luminal A, 287 (12.1%) luminal B, 167 (7.0%) HER2-enriched, 310 (13.1%) basal-like, 51 (2.2%) normal-like. We will report the results for association of molecular subtype, proliferation score, and Risk of Recurrence (ROR) scores with invasive disease-free survival (IDFS) by treatment arm at the meeting. Conclusions. The TRANS-PALLAS cohort represents one of the largest biorepositories of HR+/HER2- early breast cancer reflecting contemporary systemic management in the framework of a prospectively randomized global trial. Required tumor block submission in this phase 3 trial yielded data from unbiased whole-transcriptome RNA sequencing of the primary tumor prior to treatment from 41% of the PALLAS participants. The proportion of luminal A cancers was unexpectedly high (66%), indicating a lower-risk distribution of cancers in this population. The planned analyses of prediction and prognosis are ongoing and those results will be presented at the time of the meeting. Support: AFT, ABCSG, Pfizer, ECOG-ACRIN, NSABP Foundation, GBG, BIG; Clinicaltrials.gov Identifier: NCT02513394; https://acknowledgments.alliancefound.org Citation Format: Daniel Stover, Dominik Hlauschek, Erica Mayer, W. Fraser Symmans, Mark Watson, Iros Barozzi, Martin Filipits, Karla Ballman, Meritxell Bellet- Ezquerra, Justin Balko, Gabor Rubovszky, Nicholas Zdenkowski, Adam Brufsky, Guenther Steger, Claudine Isaacs, Sibylle Loibl, Fernando Henao, Meredith Regan, Yuan Liu, Christian Fesl, Patrick O'Brien, Angela DeMichele, Michael Gnant, Otto Metzger. Protocol-defined biomarker analysis in the PALLAS (AFT-05) adjuvant trial: Genomic subtype derived from RNA sequencing of HR+/HER2- 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 GS03-07.

Immune checkpoint therapy (ICT) causes durable tumour responses in a subgroup of patients, but it is not well known how T cell receptor beta (TCRβ) repertoire dynamics contribute to the therapeutic response. Using murine models that exclude variation in host genetics, environmental factors and tumour mutation burden, limiting variation between animals to naturally diverse TCRβ repertoires, we applied TCRseq, single cell RNAseq and flow cytometry to study TCRβ repertoire dynamics in ICT responders and non-responders. Increased oligoclonal expansion of TCRβ clonotypes was observed in responding tumours. Machine learning identified TCRβ CDR3 signatures unique to each tumour model, and signatures associated with ICT response at various timepoints before or during ICT. Clonally expanded CD8+ T cells in responding tumours post ICT displayed effector T cell gene signatures and phenotype. An early burst of clonal expansion during ICT is associated with response, and we report unique dynamics in TCRβ signatures associated with ICT response.

Importance Adding fulvestrant to anastrozole (A+F) improved survival in postmenopausal women with advanced estrogen receptor (ER)-positive/ERBB2 (formerly HER2)-negative breast cancer. However, the combination has not been tested in early-stage disease.Objective To determine whether neoadjuvant fulvestrant or A+F increases the rate of pathologic complete response or ypT1-2N0/N1mic/Ki67 2.7% or less residual disease (referred to as endocrine-sensitive disease) over anastrozole alone.Design, Setting, and Participants A phase 3 randomized clinical trial assessing differences in clinical and correlative outcomes between each of the fulvestrant-containing arms and the anastrozole arm. Postmenopausal women with clinical stage II to III, ER-rich (Allred score 6-8 or >66%)/ERBB2-negative breast cancer were included. All analyses were based on data frozen on March 2, 2023.Interventions Patients received anastrozole, fulvestrant, or a combination for 6 months preoperatively. Tumor Ki67 was assessed at week 4 and optionally at week 12, and if greater than 10% at either time point, the patient switched to neoadjuvant chemotherapy or immediate surgery.Main Outcomes and Measures The primary outcome was the endocrine-sensitive disease rate (ESDR). A secondary outcome was the percentage change in Ki67 after 4 weeks of neoadjuvant endocrine therapy (NET) (week 4 Ki67 suppression).Results Between February 2014 and November 2018, 1362 female patients (mean [SD] age, 65.0 [8.2] years) were enrolled. Among the 1298 evaluable patients, ESDRs were 18.7% (95% CI, 15.1%-22.7%), 22.8% (95% CI, 18.9%-27.1%), and 20.5% (95% CI, 16.8%-24.6%) with anastrozole, fulvestrant, and A+F, respectively. Compared to anastrozole, neither fulvestrant-containing regimen significantly improved ESDR or week 4 Ki67 suppression. The rate of week 4 or week 12 Ki67 greater than 10% was 25.1%, 24.2%, and 15.7% with anastrozole, fulvestrant, and A+F, respectively. Pathologic complete response/residual cancer burden class I occurred in 8 of 167 patients and 17 of 167 patients, respectively (15.0%; 95% CI, 9.9%-21.3%), after switching to neoadjuvant chemotherapy due to week 4 or week 12 Ki67 greater than 10%. PAM50 subtyping derived from RNA sequencing of baseline biopsies available for 753 patients (58%) identified 394 luminal A, 304 luminal B, and 55 nonluminal tumors. A+F led to a greater week 4 Ki67 suppression than anastrozole alone in luminal B tumors (median [IQR], -90.4% [-95.2 to -81.9%] vs -76.7% [-89.0 to -55.6%]; P < .001), but not luminal A tumors. Thirty-six nonluminal tumors (65.5%) had a week 4 or week 12 Ki67 greater than 10%.Conclusions and Relevance In this randomized clinical trial, neither fulvestrant nor A+F significantly improved the 6-month ESDR over anastrozole in ER-rich/ERBB2-negative breast cancer. Aromatase inhibition remains the standard-of-care NET. Differential NET response by PAM50 subtype in exploratory analyses warrants further investigation.

Background:The enteric parasite Cryptosporidium remains a treatment challenge for drinking water utilities globally due to its resistance to chlorine disinfection. However, the lack of an in vitro culture system for Cryptosporidium that is both cost-effective and reliable remains a key bottleneck in Cryptosporidium research. Methods:Here we report that the microfluidic culture of human ileocecal colorectal adenocarcinoma (HCT-8) cells under fluid shear stress enables the extended development of Cryptosporidium parvum. Specifically, the growth of C. parvum in a user-friendly pumpless microfluidic device was assessed using immunofluorescence assays, scanning electron microscopy, and quantitative polymerase chain reaction, which revealed that development continued for 10 days in total. Results:Oocysts produced within the microfluidic device were infective to fresh HCT-8 monolayers; however, these oocysts were only present at low levels. Conclusions:We anticipate that such microfluidic approaches will facilitate a wide range of in vitro studies on Cryptosporidium and may have the potential to be further developed as a routine infectivity assessment tool for the water industry.

Brain metastases can occur in nearly half of patients with early and locally advanced (stage I-III) non-small cell lung cancer (NSCLC). There are no reliable histopathologic or molecular means to identify those who are likely to develop brain metastases. We sought to determine if deep learning (DL) could be applied to routine H&E-stained primary tumor tissue sections from stage I-III NSCLC patients to predict the development of brain metastasis. Diagnostic slides from 158 patients with stage I-III NSCLC followed for at least 5 years for the development of brain metastases (Met+, 65 patients) versus no progression (Met-, 93 patients) were subjected to whole-slide imaging. Three separate iterations were performed by first selecting 118 cases (45 Met+, 73 Met-) to train and validate the DL algorithm, while 40 separate cases (20 Met+, 20 Met-) were used as the test set. The DL algorithm results were compared to a blinded review by four expert pathologists. The DL-based algorithm was able to distinguish the eventual development of brain metastases with an accuracy of 87% (p < 0.0001) compared with an average of 57.3% by the four pathologists and appears to be particularly useful in predicting brain metastases in stage I patients. The DL algorithm appears to focus on a complex set of histologic features. DL-based algorithms using routine H&E-stained slides may identify patients who are likely to develop brain metastases from those who will remain disease free over extended (>5 year) follow-up and may thus be spared systemic therapy. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Abstract Introduction: A phase III multicenter prospective randomized clinical trial called “Comparing an Operation to Monitoring, with or without Endocrine Therapy (COMET)” (NCT02926911) assesses the risks/benefits of active monitoring (AM) versus surgery for women with low-risk ductal carcinoma in situ (DCIS). It is funded by the Patient-Centered Outcomes Research Institute and enrolled 997 women between 06/30/17 and 01/13/23. Research Patient Advocates (PAs) have been embedded from the study design stage and continue to provide guidance as part of the COMET leadership team. The COMET biobank is funded by independent foundations and is managed through monthly Translational Working Group (TWG) meetings. The TWG includes PAs, clinicians, pathologists, radiologists, and researchers from multiple institutions who discuss topics like categorization of biospecimens into discovery/validation sets; development of a pathology workflow/sample tracking process; use of small samples; and potential areas of future research/technologies that may improve DCIS diagnostics, prognostics, and care management. Methods: The TWG leveraged the existing Alliance Foundation Trials, LLC biobank infrastructure and facilitates the collection, submission, storage and analysis/use of blood, tissue, and breast images collected at specified timepoints and stored in central tissue/image repositories. PAs are active and integral in the TWG, assisting with logistical issues (contracts, transfer agreements, resource requests); communicating with sites; identifying study topics and biomarkers relevant to diverse patients; providing guidance on commercial predictive/prognostic tests; promoting effective stewardship of samples; ensuring overall focus remains on advancing clinical utility; and reporting translational study results to trial participants who agreed to donate samples/images. Results: Over 90% of requested samples/images have been submitted by ˃85 sites. Each patient’s biospecimens and pathology images are linked and de-identified for research. Use of artificial intelligence (AI) is being considered to assist in sample review. TWG members have complementary areas of expertise/experience and promote active stewardship for effective management of these scarce resources. PAs have played key roles concerning equitable data-sharing and acceleration of data and material transfer agreements. They have also been active in development of standards for discovery/training sets, validation test sets; communication procedures for patient cases that progress to future breast events; ways to catalog technologies (e.g., multi-omics, AI); and in research proposal review. Consensus has been achieved regarding major issues such as authorship, biospecimen custodianship, intellectual property, and criteria relevant to patient needs. Logistical barriers, including data sharing and technicalities of biospecimen release, have been resolved. The TWG also played an integral role in resolving recruitment challenges to COMET by creating standard pathology eligibility criteria, resulting in evidence-based protocol amendments that increased accrual. A retrospective review of biospecimens has been performed to determine adequacy for ensuing correlative molecular and spatial profiling studies. Conclusion: PAs help the COMET TWG set policy, and oversee biospecimen/image collection, and biobank use and sharing. PA input also facilitates equitable, transparent research studies and technology development that can improve personalized decisions for surgery versus AM in women with low-risk DCIS. PAs in the TWG aim to integrate the diagnostic and prognostic tools developed as part of the COMET study into future patient care. Citation Format: Deborah Collyar, Desiree Basila, Thomas Lynch, Stuart Schnitt, Jeffrey Marks, Siri Strand, Terry Hyslop, Sunil Badve, Mark Watson, H. T. Carisa Le-Petross, Lars Grimm, Robert West, Anna Weiss, Anna Rapperport, Lorraine King, Rachel Factor, Marc Ryser, Ann Partridge, E Shelley Hwang, Alastair Thompson. Added Value from Patient Advocates in a Translational Working Group: the COMET Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-13-04.

538 Background: The phase 3 PALLAS trial compared 2 years of the CDK4/6 inhibitor palbociclib with endocrine therapy of provider choice, versus endocrine therapy alone, as adjuvant treatment for patients (pts) with Stage II-III hormone receptor-positive HER2-negative (HR+/HER2-) breast cancer. The SET2,3 index adjusts the measurement of SETER/PR index of endocrine receptor-related transcriptional activity with a baseline prognostic index (BPI) derived from tumor size (T), number of involved lymph nodes (N) and gene expression levels of ESR1, PGR, ERBB2 and AURKA (RNA4 subtype score). High SET2,3 (index ≥ 2.10) represents high endocrine sensitivity with favorable prognosis. Clinical outcome results from PALLAS were previously published, and the trial now has 5-year median follow-up. Methods: Participants in PALLAS provided a tumor tissue block prior to randomization. RNA was extracted from samples with sufficient tumor tissue and cellularity (>25mm2 with ≥20% cancer nuclei). SET2,3 index was measured from 300ng total RNA using the QuantiGene Plex platform (ThermoFisher, Waltham, MA) following the manufacturer’s protocol and using pre-defined quality control (QC) parameters and cut point. Results from primary tumor samples prior to systemic therapy were analyzed. Invasive disease-free survival (iDFS) was summarized with Kaplan-Meier plots using log-rank test. Cox models were adjusted for treatment arm assignment, with a treatment arm by SET index value interaction term to test for prediction of palbociclib benefit. The pre-defined level of significance was a two-sided 0.05. Results: There were 4075 pts from the total PALLAS population (N=5796) who provided a primary tumor sample that met pre-analytical requirements to perform the SET assay, from which 3388 (83%) results passed quality control, including 3093 from a sample obtained prior to receiving systemic therapy (1559 in palbociclib arm and 1534 in the control arm). SET2,3 index could not be calculated for 12 pts due to missing tumor or nodal information. There was no evidence of an interaction between treatment arm and SET indices (continuous) for iDFS: SET2,3 index interaction p=0.12 and SETER/PR index interaction p=0.92. Estimated 5-year iDFS was superior for those with high SET2,3: iDFS was 91.4% (95%CI 89.9–92.8) in 1719 (55.8%) pts with high SET2,3, versus 78.5% (95%CI 76.0–80.8) in 1362 (44.2%) pts with low SET2,3 (HR 0.38, 95%CI 0.31–0.47, p<0.0001). The SETER/PR index was also significantly associated with iDFS (HR 0.70 per 0.5 units, 95%CI 0.65–0.77, p<0.0001). Conclusions: There was no evidence that the SET2,3 or SETER/PR index of endocrine-related transcriptional activity predicts benefit from palbociclib treatment. SET2,3 index was strongly prognostic for pts with Stage II-III breast cancer, with excellent 5-year IDFS for pts classified as SET2,3 high. Clinical trial information: NCT02513394 .

Abstract To attain higher hydrocarbon production and maintain oil and gas rates at optimal values for a determined time require prudent drilling, and subsequently completing and fracturing the well. are some of the essential criteria for positive cash flow. Oil and gas production is essential to meet world energy demand. The objective of any hydrocarbon field development is to attain higher sustained production rates. The need for the use of best practices in drilling, completion, fracturing, and production management during the duration of a well becomes essential. Drilling of long horizontal laterals through the reservoir section has been a game-changing alternate to vertical wells. Production is substantially increased with horizontal wells; long-term sustainability is achieved and development cost is considerably reduced. This paper highlights state of the art completions and fracturing technology used in moderate to tight oil and gas reservoirs for enhanced and sustained productivity. After proper assessment of the field using data from geoscience, delineation wells, and logs, an optimal horizontal drilling design is put together. Wells drilled in the field can be completed in multiple ways depending on the reservoir properties, well trajectory, and production objectives. The best completions are those that are customized for the reservoir parameters and well trajectory and will provide optimal inflow of reservoir fluids to the well. The best fracturing technique is to place a high conductivity path between the well and reservoir without causing damage to either the reservoir or completions. Depending on the reservoir, acid or proppants are selected such that fracture conductivity is maintained through most of well life. Many examples are provided in this paper.

538 Background: The phase 3 PALLAS trial compared 2 years of the CDK4/6 inhibitor palbociclib with endocrine therapy of provider choice, versus endocrine therapy alone, as adjuvant treatment for patients (pts) with Stage II-III hormone receptor-positive HER2-negative (HR+/HER2-) breast cancer. The SET2,3 index adjusts the measurement of SET ER/PR index of endocrine receptor-related transcriptional activity with a baseline prognostic index (BPI) derived from tumor size (T), number of involved lymph nodes (N) and gene expression levels of ESR1, PGR, ERBB2 and AURKA (RNA4 subtype score). High SET2,3 (index ≥ 2.10) represents high endocrine sensitivity with favorable prognosis. Clinical outcome results from PALLAS were previously published, and the trial now has 5-year median follow-up. Methods: Participants in PALLAS provided a tumor tissue block prior to randomization. RNA was extracted from samples with sufficient tumor tissue and cellularity (>25mm 2 with ≥20% cancer nuclei). SET2,3 index was measured from 300ng total RNA using the QuantiGene Plex platform (ThermoFisher, Waltham, MA) following the manufacturer’s protocol and using pre-defined quality control (QC) parameters and cut point. Results from primary tumor samples prior to systemic therapy were analyzed. Invasive disease-free survival (iDFS) was summarized with Kaplan-Meier plots using log-rank test. Cox models were adjusted for treatment arm assignment, with a treatment arm by SET index value interaction term to test for prediction of palbociclib benefit. The pre-defined level of significance was a two-sided 0.05. Results: There were 4075 pts from the total PALLAS population (N=5796) who provided a primary tumor sample that met pre-analytical requirements to perform the SET assay, from which 3388 (83%) results passed quality control, including 3093 from a sample obtained prior to receiving systemic therapy (1559 in palbociclib arm and 1534 in the control arm). SET2,3 index could not be calculated for 12 pts due to missing tumor or nodal information. There was no evidence of an interaction between treatment arm and SET indices (continuous) for iDFS: SET2,3 index interaction p=0.12 and SET ER/PR index interaction p=0.92. Estimated 5-year iDFS was superior for those with high SET2,3: iDFS was 91.4% (95%CI 89.9–92.8) in 1719 (55.8%) pts with high SET2,3, versus 78.5% (95%CI 76.0–80.8) in 1362 (44.2%) pts with low SET2,3 (HR 0.38, 95%CI 0.31–0.47, p<0.0001). The SET ER/PR index was also significantly associated with iDFS (HR 0.70 per 0.5 units, 95%CI 0.65–0.77, p<0.0001). Conclusions: There was no evidence that the SET2,3 or SET ER/PR index of endocrine-related transcriptional activity predicts benefit from palbociclib treatment. SET2,3 index was strongly prognostic for pts with Stage II-III breast cancer, with excellent 5-year IDFS for pts classified as SET2,3 high. Clinical trial information: NCT02513394 .