Ductal Carcinoma In Situ (DCIS) is a non-obligate precursor of invasive breast cancer. Due to a lack of reliable prognostic markers, nearly all women with DCIS undergo intensive treatment-often unnecessarily. The LORD trial addresses this by offering active surveillance to women with screen-detected, ER-positive, HER2-negative, grade 1 or 2 DCIS, aiming to reduce overtreatment. To support this, we developed a deep learning pipeline based on foundation models to predict grade, ER, and HER2 status directly from H&E-stained digitized pathology slides. Models were trained and tested on a Dutch multicenter dataset (n = 887) and externally validated on a UK dataset (n = 259). On the Dutch data, the models achieved mean AUROCs of 0.90 (ER), 0.84 (HER2), and 0.86 (grade); external validation yielded 0.80, 0.74, and 0.75, respectively. Using these outputs, we stratified patients according to active surveillance criteria, reaching balanced accuracies of 0.81 (Dutch) and 0.64 (UK), with corresponding NPVs of 0.86 and 0.76. Our models generalize across cohorts and reliably predict key biomarkers, supporting the identification of DCIS patients eligible for less aggressive management.

Ki-67 is a well-established marker of tumour proliferation and an important prognostic and predictive biomarker in breast cancer, particularly in hormone receptor-positive (HR-positive), HER2-negative disease. Despite its biological relevance, clinical implementation has been limited by the reported interobserver and interlaboratory variability. Recent therapeutic advances have created an increased need for accurate and reproducible Ki-67 assessment in clinical practice. This review summarizes the biological basis for the use of Ki-67 as a marker of proliferation, technical requirements for reliable immunohistochemistry and the influence of pre-analytical and analytical variables on staining performance. We evaluate established and emerging scoring approaches and provide scoring recommendations for practising pathologists. A simplified calibrated global assessment method is presented as an alternative to exhaustive visual quantification that preserves its accuracy while substantially reducing scoring time and avoiding the variability of estimated methods. Image analysis/artificial intelligence (AI) using validated algorithms is recommended where available. We also review the role of Ki-67 in predicting response to neoadjuvant endocrine and chemotherapy, its integration into prognostic models such as the PEPI score, and its utility in selecting patients for adjuvant CDK4/6 inhibition. The limitations of fixed cut-off values are discussed, together with the potential advantages of tiered classification and continuous modelling. Finally, we outline the growing role of digital pathology and AI, which have demonstrated improved reproducibility, reduced turnaround time, and prognostic performance superior to manual scoring. Ki-67 is a clinically meaningful biomarker, the value of which can only be fully realized through rigorous standardization, validated scoring approaches and close communication between pathologists and oncologists. This guidance provides a practical framework for high-quality Ki-67 assessment and supports its safe and effective integration into contemporary breast cancer management.

Biomarkers for specific cytotoxic chemotherapy sensitivity could better inform drug selection. Both CEP17 duplication and abnormal Topoisomerase 2 copy number appear associated with anthracycline sensitivity in the adjuvant setting (Bartlett et al 2015). This data is however not currently applied clinically. Taxanes are a routine component of adjuvant and neoadjuvant chemotherapy either in combination or sequenced with anthracyclines, or increasingly used in the absence of anthracyclines. ROSCO: ISRCTN15094808 was designed to prospectively evaluate the clinical utility of these two biomarkers for initial neoadjuvant chemotherapy selection. Between November 2015 and May 2023, 990 consenting patients with early breast cancer considered suitable for neoadjuvant chemotherapy were randomised to four cycles of either Epirubicin and Cyclophosphamide with optional 5 Fluorouracil ((F)EC), or Docetaxel and Cyclophosphamide (TC). Patients with Grade 1 or 2 ER Rich, PR Rich, HER-2 negative tumours and all T1 N0 tumours were excluded. All HER-2 positive cancers were treated with concurrent anti HER-2 antibodies. Participants were stratified by centrally assessed biomarker status as biomarker normal (BM normal) with both CEP17 and TOP2A normal, or biomarker abnormal (BM abnormal) with CEP17 duplication and/or TOP2A abnormal. Surgery was performed after 4 cycles of chemotherapy; where pathological complete response (pCR) was not achieved, crossover to the alternative treatment arm for a further 4 cycles was given in an adjuvant setting. Crossover before surgery was permitted where interim biopsy after 4 cycles confirmed viable residual disease. The primary endpoint of the study is pCR ypT0/Tis ypN0 after initial neoadjuvant chemotherapy. Of the 990 patients consented, 496 were randomised to TC and 494 to (F)EC. 24 patients with no cancer seen in interim biopsy received further neoadjuvant chemotherapy and also had pCR at final surgery, these are considered in the primary analysis as non pCR. Data from 950 patients are evaluable for the primary endpoint. Overall pCR was 245 (26%): the TC arm was 131 (27%) and (F)EC arm was 114(24%). Overall BM was normal in 233 (24%) with BM abnormal in 756 (76%). With TC the pCR percentages for BM normal and abnormal were very similar: 30% and 27% respectively. For (F)EC BM normal, pCR is 17% and for FEC BM abnormal, it is 26%. Final data cleaning is ongoing, testing for treatment by biomarker interaction will be presented. Higher response to (F)EC in the biomarker abnormal group was observed across all pathological subtypes tested. Sensitivity analysis excluding 35 TC and 22 (F)EC patients where crossover chemotherapy was given off protocol neoadjuvantly despite a negative core biopsy or where patients withdrew prior to the primary endpoint was conducted. The pCR proportions observed in the treatment by biomarker groups were not impacted. Preliminary analysis of this large prospective evaluation of CEP17 and TOP2A as potential predictors of anthracycline sensitivity conducted in a neoadjuvant context shows that evaluation of these biomarkers shows no predictive value for sensitivity to TC but demonstrates differential pCR to (F)EC. Suggesting women with BM abnormal cancers are likely to benefit more from inclusion of anthracyclines. Anthracycline-free chemotherapy may be considered as an option for women with BM normal cancers. This work was supported by CRUK [CRUK/12/046/ A15756] and Bristol Myers Squibb. Citation Format: Daniel Rea, S. Pirrie, L. Hayward, S. Chan, M. Varughese, S. Spensley, U. Barthakur, M. MacKenzie, S. J. Bowden, C. Gaunt, E. Southgate, N. Nicholson, P. Wetherell, M. Soden, L. Billingham, C. Brookes, D. Cameron, J. Starczynski, J. Dowds. H. Earl, R. Ste. ROSCO: Response to Optimal Selection of neoadjuvant Chemotherapy in Operable breast cancer: Randomised phase III, stratified biomarker trial of neoadjuvant 5-Fluorouracil,Epirubicin & Cyclophosphamide vs Docetaxel & Cyclophosphamide chemotherapy [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 RF3-07.

The Breast Cancer Index (BCI) was previously shown to identify ~20% of postmenopausal patients with early stage, hormone receptor positive (HR+), node negative (N0) breast cancer with minimal (<5%) risk of 10-year distant recurrence (DR) even without receiving adjuvant endocrine therapy (ET). This prospective-retrospective study further validated the BCI minimal risk classification in postmenopausal patients with early-stage, HR + HER2– N0 breast cancer from the Netherlands Cancer Registry (NCR) and the Tamoxifen and Exemestane Adjuvant Multinational (TEAM, NCT00279448, NCT00032136) randomized trial who received 5 years of primary adjuvant ET. BCI classified approximately 15% of patients as minimal risk. In the NCR cohort (n = 1264 out of 15,053 HR+ patients in the registry), risks of DR in the minimal, low, intermediate, and high groups were 4.8%, 3.3%, 8.0%, and 12.4%, respectively (P < 0.001). In the TEAM cohort (n = 978 out of 3544 in the BCI study), DR risks were 3.8%, 8.3%, 12.6% and 22.7% (P < 0.001). In multivariate analyses, BCI risk scores provided independent information over standard prognostic factors (P < 0.001). This study confirmed the ability of the adjusted BCI model to identify postmenopausal women with HR + HER2– N0 breast cancer who are at minimal risk of DR and may consider de-escalating adjuvant ET.

TPS625 Background: Mammographic screening programmes reduce breast cancer mortality but detect many small tumours with favourable biology which may not progress. These are treated with surgery and adjuvant therapies, but associated morbidities mean there is a need to reduce overtreatment. Minimally invasive treatments such as vacuum-assisted excision (VAE) have been described but there is no prospective randomised evidence to support their routine use. SMALL (ISRCTN 12240119) is designed to establish the feasibility of using VAE to treat small tumours detected within the UK NHS Breast Screening Programme (BSP). Methods: Phase III multicentre randomised trial comparing surgery with VAE for screen-detected good prognosis cancers. Eligibility criteria are age ≥47 years, unifocal grade 1 tumours (maximum diameter 15mm), strongly ER/PR+ve and HER2-ve, with negative axillary staging. Patients are randomised 2:1 to VAE or surgery, with no axillary surgery in the VAE arm. Excision is assessed radiologically, and if incomplete, patients undergo surgery. Adjuvant radiotherapy and endocrine therapy are mandated in the VAE arm. Co-primary end-points are 1) Non-inferiority comparison of the requirement for a second procedure. 2) Single arm analysis of local recurrence (LR) at 5 years after VAE. Recruitment of 800 patients will permit demonstration of 10% non-inferiority of VAE for requirement of a second procedure, ensuring sufficient patients for single arm analysis of LR rates, where expected LR free survival is 99% at 5 years, with an undesirable survival probability after VAE of 97%. Secondary outcome measures include time to ipsilateral recurrence, overall survival, complications, quality of life and health economic analysis. A QuinteT Recruitment Intervention (QRI) is integrated throughout SMALL to optimise recruitment and informed consent. Recruitment challenges are identified by analysing recruiter/patient interviews, audio-recordings of trial discussions, and by review of screening, eligibility and recruitment data and study documentation. Solutions are developed collaboratively, including recruiter feedback and recruitment tips documents. Results: At 10 th February 2023, 231 patients had been recruited from 32 centres, (~45% of eligible patients), with per site recruitment of 0.4-0.5 patients/month. Based on preliminary QRI findings, a recruitment tips document has been circulated (on discussing SMALL, providing balanced information on treatment options and explaining randomisation), with individual recruiter feedback underway and wider feedback planned shortly. Conclusion: SMALL has excellent recruitment to date, confirming feasibility and acceptability, and is expected to have a global impact on treatment of screen-detected breast cancer. Clinical trial information: ISRCTN12240119 .

Supplemental Table 2. Distribution of patients as defined by BCI prognostic (BCI/BCIN+) and BCI predictive (BCI (H/I)).

Supplemental Figure 1. Continuous risk curves of BCI and BCIN+ for overall 10-year DR in patients who did not receive adjuvant chemotherapy. A: risk of overall 10-year DR as a function of continuous BCI for N0 patients (N=1196); B: risk of overall 10-year DR as a function of continuous BCIN+ for N1 patients (N=1234); C: risk of overall 10-year DR as a function of continuous BCI for N0 HER2- patients (N=978); D: risk of overall 10-year DR as a function of continuous BCIN+ for N1 HER2- patients (N=1067).

Supplemental Table 1. Prognostic performance of BCI and BCIN+ optimized cut-points for late DR in all patients with N0 and N1 breast cancers, as well as in HER2- subsets, respectively.

BACKGROUND:The humoral and T-cell responses to booster COVID-19 vaccine types in multidisease immunocompromised individuals who do not generate adequate antibody responses to two COVID-19 vaccine doses, is not fully understood. The OCTAVE DUO trial aimed to determine the value of third vaccinations in a wide range of patients with primary and secondary immunodeficiencies. METHODS:OCTAVE-DUO was a prospective, open-label, multicentre, randomised, controlled, phase 3 trial investigating humoral and T-cell responses in patients who are immunocompromised following a third vaccine dose with BNT162b2 or mRNA-1273, and of NVX-CoV2373 for those with lymphoid malignancies. We recruited patients who were immunocompromised from 11 UK hospitals, aged at least 18 years, with previous sub-optimal responses to two doses of SARS-CoV-2 vaccine. Participants were randomly assigned 1:1 (1:1:1 for those with lymphoid malignancies), stratified by disease, previous vaccination type, and anti-spike antibody response following two doses. Individuals with lived experience of immune susceptibility were involved in the study design and implementation. The primary outcome was vaccine-specific immunity defined by anti-SARS-CoV-2 spike antibodies (Roche Diagnostics UK and Ireland, Burgess Hill, UK) and T-cell responses (Oxford Immunotec, Abingdon, UK) before and 21 days after the third vaccine dose analysed by a modified intention-to-treat analysis. The trial is registered with the ISRCTN registry, ISRCTN 15354495, and the EU Clinical Trials Register, EudraCT 2021-003632-87, and is complete. FINDINGS:Between Aug 4, 2021 and Mar 31, 2022, 804 participants across nine disease cohorts were randomly assigned to receive BNT162b2 (n=377), mRNA-1273 (n=374), or NVX-CoV2373 (n=53). 356 (45%) of 789 participants were women, 433 (55%) were men, and 659 (85%) of 775 were White. Anti-SARS-CoV-2 spike antibodies measured 21 days after the third vaccine dose were significantly higher than baseline pre-third dose titres in the modified intention-to-treat analysis (median 1384 arbitrary units [AU]/mL [IQR 4·3-7990·0] compared with median 11·5 AU/mL [0·4-63·1]; p<0·001). Of participants who were baseline low responders, 380 (90%) of 423 increased their antibody concentrations to more than 400 AU/mL. Conversely, 166 (54%) of 308 baseline non-responders had no response after the third dose. Detectable T-cell responses following the third vaccine dose were seen in 494 (80%) of 616 participants. There were 24 serious adverse events (BNT612b2 eight [33%] of 24, mRNA-1273 12 [50%], NVX-CoV2373 four [17%]), two (8%) of which were categorised as vaccine-related. There were seven deaths (1%) during the trial, none of which were vaccine-related. INTERPRETATION:A third vaccine dose improved the serological and T-cell response in the majority of patients who are immunocompromised. Individuals with chronic renal disease, lymphoid malignancy, on B-cell targeted therapies, or with no serological response after two vaccine doses are at higher risk of poor response to a third vaccine dose. FUNDING:Medical Research Council, Blood Cancer UK.

AbstractPurpose:Patients with early-stage hormone receptor–positive (HR+) breast cancer face a prolonged risk of recurrence even after adjuvant endocrine therapy. The Breast Cancer Index (BCI) is significantly prognostic for overall (0–10 years) and late (5–10 years) distant recurrence (DR) risk in N0 and N1 patients. Here, BCI prognostic performance was evaluated in HR+ postmenopausal women from the Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial.Experimental Design:3,544 patients were included in the analysis (N = 1,519 N0, N = 2,025 N+). BCI risk groups were calculated using pre-specified cutoff points. Kaplan–Meier analyses and log-rank tests were used to assess the prognostic significance of BCI risk groups based on DR. Hazard ratios (HR) and confidence intervals (CI) were calculated using Cox models with and without clinical covariates.Results:For overall 10-year DR, BCI was significantly prognostic in Ni0 (N = 1,196) and N1 (N = 1,234) patients who did not receive prior chemotherapy (P < 0.001). In patients who were DR-free for 5 years, 10-year late DR rates for low- and high-risk groups were 5.4% and 9.3% (N0 cohort, N = 1,285) and 4.8% and 12.2% (N1 cohort, N = 1,625) with multivariate HRs of 2.25 (95% CI, 1.30–3.88; P = 0.004) and 2.67 (95% CI, 1.53–4.63; P < 0.001), respectively. Late DR performance was substantially improved using previously optimized cutoff points, identifying BCI low-risk groups with even lower 10-year late DR rates of 3.8% and 2.7% in N0 and N1 patients, respectively.Conclusions:The TEAM trial represents the largest prognostic validation study for BCI to date and provides a more representative assessment of late DR risk to guide individualized treatment decision-making for HR+ patients with early-stage breast cancer.

Purpose: Adjuvant abemaciclib plus endocrine therapy was approved for high-risk early breast cancer patients within the NHS in June 2022, based on the phase III study Monarch E trial demonstrating improved invasive disease-free survival and an acceptable safety profile compared with endocrine therapy alone [1,2]. The aim of our study was to assess the adverse event profile and tolerability of adjuvant abemaciclib/endocrine therapy in real-world clinical practice in comparison to the trial.

Abstract Background: Individualized risk assessment of distant recurrence (DR) is critical for early-stage HR+ breast cancer patients, as prolonged risk of recurrence continues even after completing 5 years of adjuvant endocrine therapy. The Breast Cancer Index (BCI) is a guideline-endorsed, validated gene expression assay that provides an individualized risk of overall (0-10y) and late (5-10y) DR and predicts the likelihood of benefit from extended endocrine therapy. The current BCI assay reports prognostic risk estimates based on tamoxifen-treated patients from the Stockholm (STO-3) cohort for node-negative (N0) patients, enrolled between 1976 through 1990 and a retrospective cohort from Massachusetts General Hospital (MGH) for patients with 1 to 3 positive nodes (N1), diagnosed between 1993 and 2007, of which approximately 50% were tamoxifen-treated. More recently, additional validation was completed in the Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial, in which patients were enrolled between 2001 and 2006. Here, individualized DR risk estimates from the TEAM trial were compared with those from Stockholm and MGH cohorts. Methods: For the TEAM translational study, BCI testing was performed blinded to clinical outcome and BCI and BCIN+ risk scores were calculated as previously described. A total of 2910 postmenopausal patients with HR+ breast cancer, including 1285 N0 and 1625 N1 patients, who remained DR-free for five years were analyzed to determine the risk of late DR. Cox proportional hazard models using Breslow estimates were used to calculate the risk of late DR as a function of continuous BCI risk scores. Results: Late DR risk estimates from both the TEAM trial and the Stockholm/MGH cohorts are summarized in the table below. In N0 patients, comparison of 5-10y risk estimates of late DR observed in TEAM patients were higher than those in the Stockholm cohort for BCI scores less than 8.0, but reduced for BCI scores greater than 8.0. Risk estimates differed by 1.5% for a BCI score of 0 and -4.3% for a BCI score of 10. A similar pattern was observed for N1 patients between the TEAM and MGH cohorts, with risk estimates from TEAM trial being higher for BCI scores less than 8.0 but reduced for BCI scores greater than 8.0 compared to those from the MGH cohort. Conclusions: BCI prognostic validation in the TEAM trial enabled the characterization of DR risk that is more compatible with the current standard of care in the US, as postmenopausal patients were all treated with at least 2-3 years or 5 years of primary adjuvant endocrine therapy with an aromatase inhibitor. Results from the TEAM study provide a more representative assessment of late DR risk to guide individualized treatment decision-making for HR+ early-stage breast cancer patients. Table. Citation Format: John MS Bartlett, Yi Zhang, Gregory Pond, Jenna Wong, Keying Xu, Melanie Spears, Elizabeth Mallon, Karen Taylor, Annette Hasenburg, Christos Markopoulos, Luc Dirix, Caroline Seynaeve, Cornelis J.H. van de Velde, Daniel Rea, Adam Brufsky, Olle Stål, Dennis Sgroi, Catherine Schnabel, Kai Treuner, Jane Bayani. Breast Cancer Index and comparative analysis of late distant recurrence risk with results from the TEAM 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 PO5-01-11.

Supplemental Figure 2. Continuous risk curves of BCI and BCIN+ for late 10-year DR in patients DR-free at 5 years. A: risk of 10-year late DR as a function of continuous BCI for N0 patients (N=1285); B: risk of 10-year late DR as a function of continuous BCIN+ for N1 patients (N=1625); C: risk of 10-year late DR as a function of continuous BCI for N0 HER2- patients (N=1063); D: risk of 10-year late DR as a function of continuous BCIN+ for N1 HER2- patients (N=1394).

Whilst SARS-CoV-2 mRNA vaccines generate high neutralising antibodies (nAb) in most individuals, haematopoietic stem cell transplant (HSCT) and chimeric antigen receptor T-cell (CAR-T) recipients respond poorly. HSCT/CAR-T treatment ablates existing immune memory, with recipients requiring revaccination analogous to being vaccine naive. An optimal revaccination strategy for this cohort has not been defined. Factors predicting immunogenicity following three ancestral SARS-CoV-2 vaccines were assessed in 198 HSCT/CAR-T recipients and 96 healthcare workers (HCWs) recruited to multicentre studies. Only 25% of HSCT/CAR-T recipients generated nAbs following one dose, with titres 167-fold and 7-fold lower than that in HCWs after the first and second doses, respectively. Lower post-second dose nAb titres were associated with older age, rituximab use, and previous HSCT. ChAdOx1-S recipients were more likely to generate nAbs compared with mRNA vaccines, with titres comparable to HCWs. In contrast, nAbs were significantly lower in HSCT/CAR-T recipients than HCWs after mRNA vaccination. The poor first-dose immunogenicity in HSCT/CAR-T recipients suggests a minimum licensed dosing interval could limit the period of vulnerability following HSCT/CAR-T. The relative preservation of nAbs with ChAdOx1-S vaccination highlights the importance of evaluating alternative platforms to mRNA vaccination within this highly vulnerable clinical cohort.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune responses and infection outcomes were evaluated in 2,686 patients with varying immune-suppressive disease states after administration of two Coronavirus Disease 2019 (COVID-19) vaccines. Overall, 255 of 2,204 (12%) patients failed to develop anti-spike antibodies, with an additional 600 of 2,204 (27%) patients generating low levels (<380 AU ml −1 ). Vaccine failure rates were highest in ANCA-associated vasculitis on rituximab (21/29, 72%), hemodialysis on immunosuppressive therapy (6/30, 20%) and solid organ transplant recipients (20/81, 25% and 141/458, 31%). SARS-CoV-2-specific T cell responses were detected in 513 of 580 (88%) patients, with lower T cell magnitude or proportion in hemodialysis, allogeneic hematopoietic stem cell transplantation and liver transplant recipients (versus healthy controls). Humoral responses against Omicron (BA.1) were reduced, although cross-reactive T cell responses were sustained in all participants for whom these data were available. BNT162b2 was associated with higher antibody but lower cellular responses compared to ChAdOx1 nCoV-19 vaccination. We report 474 SARS-CoV-2 infection episodes, including 48 individuals with hospitalization or death from COVID-19. Decreased magnitude of both the serological and the T cell response was associated with severe COVID-19. Overall, we identified clinical phenotypes that may benefit from targeted COVID-19 therapeutic strategies.