Citations

Abstract Objective . Phase gating is a critical technique to mitigate tumor motion during radiotherapy, particularly in spot-scanned particle therapy where internal motion can interfere with dynamic spot scanning patterns and, simultaneously, introducing substantial range uncertainties. However, the current commercial state of the art in real-time phase prediction is challenged by patient-specific breathing variability as well as detection and delivery system latencies. This leads to suboptimal efficiency, mis-timed radiation delivery and requires frequent manual intervention. This study aims to improve phase prediction accuracy using deep learning (DL)-based time series forecasting to enable more accurate dose delivery. Approach . Retrospective breathing waveforms from 69 proton therapy patients, sampled at 30 Hz, were labeled with inspiratory peaks and assigned subjective regularity scores (four levels). DL models with various architectures were trained using waveform amplitude to predict current or future breathing phases. Model performance was evaluated using mean squared error, phase binning accuracy, and timing deviation for radiation on/off events. Bayesian optimization was used for hyperparameter tuning. Results were compared between models and against a commercial algorithm currently in clinical use. Main Results . The curated waveform dataset included 165 242 s for training, 24 057 s for validation, and 30 322 s for testing, with an additional 40 604 s from separate patients for extended validation. The long short-term memory and temporal fusion transformer models significantly outperformed the commercial algorithm, improving phase prediction accuracy by nearly 20% and reducing timing deviations across all regularity levels. Significance . DL-based time series forecasting may substantially improve breathing phase prediction accuracy over current clinically available methods, offering a more precise and reliable approach to phase-gated radiation delivery.

Abstract Studies have reported conflicting findings regarding the contribution of germline variants or somatic genomic drivers to racial disparities in multiple myeloma. To comprehensively investigate somatic drivers in relation to inherited genetics in multiple myeloma, we combined newly sequenced whole-genome sequencing data with publicly available datasets (total n = 1,286). Overall, we did not identify germline or somatic genomic differences that explain the different risk of developing multiple myeloma between patients with genetic similarity to African (AFR) or European (EUR) reference populations. A difference in the detectability and timing of APOBEC-associated and germinal center mutational activity was observed. Integrating epidemiologic data and mutational signature-based temporal estimates, we challenge the assumption that individuals in the AFR group develop multiple myeloma at a younger age. Finally, we demonstrate that, with equal access to efficacious therapies, patients in the AFR and EUR groups have equivalent clinical outcomes. Significance: Multiple myeloma is reported to occur at higher rates in individuals who self-identify as non-Hispanic Black. In this large dataset, genomic drivers occur at the same rate among ancestry groups, except for APOBEC mutagenesis. With equivalent therapy, clinical outcomes did not differ for patients grouped by genetic ancestry similarity.

Abstract Background World Symposium on Pulmonary Hypertension (WSPH) Group 2 pulmonary hypertension (PH) is a clinically integrated phenotype attributed to left heart disease, whereas pre- versus post-capillary classification is operationalized primarily by pulmonary capillary wedge pressure (PCWP). Although current recommendations emphasize contextual interpretation and provocative testing for intermediate PCWP values, the relationship between PCWP-based classification and underlying phenotype has not been systematically evaluated. We aim to quantify phenotype–hemodynamic discordance across the PCWP spectrum and evaluate a staged physiology-guided framework incorporating inhaled nitric oxide (iNO), ventricular geometry, and provocative testing. Methods We studied 1,032 participants from the NHLBI-sponsored PVDOMICS cohort with multidisciplinary adjudicated phenotypes integrating clinical, imaging, physiologic, and hemodynamic data. Stage-specific PCWP thresholds classified pre- versus post-capillary physiology at rest, during iNO, and during provocation (fluid challenge or invasive cardiopulmonary exercise testing [iCPET]). Echocardiographic right ventricular-to-left ventricular (RV/LV) ratio was evaluated as a marker of ventricular interdependence. Restricted cubic spline and staged concordance analyses defined certainty-based PCWP ranges and incremental diagnostic yield. Results Adjudicated Group 2 PH was present in 37.0% of participants. Resting PCWP demonstrated good discrimination (AUC 0.86), but substantial bidirectional phenotype–hemodynamic discordance persisted across intermediate PCWP ranges. At a resting PCWP of 12 mmHg, 25% of participants classified as pre-capillary had adjudicated Group 2 PH, whereas at 18 mmHg, 35% classified as post-capillary remained discordant non–Group 2. Concordance did not approach 90% until PCWP values were <9 mmHg or >24 mmHg. Dynamic testing incrementally improved concordance within these overlap zones. Nearly half of adjudicated Group 2 PH participants (46.5%) were not identified by resting PCWP alone; incorporation of iNO and provocative testing increased cumulative Group 2 identification by 63.4% and improved sensitivity from 79.9% to 83.7%. Model discrimination improved from an AUC of 0.863 to 0.908 (likelihood-ratio P<0.001). iNO increased PCWP in discordant Pre/G2 participants, unmasking latent left-sided limitation, while lowering PCWP in discordant Post/NonG2 participants, consistent with ventricular interdependence. RV/LV ratio ≥0.94 reduced discordant Post/NonG2 classification by 70.5%, and incorporation of PCWP/cardiac output slope improved physiologic specificity during exercise. Conclusions Group 2 PH is a dynamic, load-dependent phenotype inadequately characterized by resting PCWP alone. Intermediate PCWP values represent continuous probabilities of bidirectional discordance rather than discrete diagnostic states. A staged physiology-guided approach integrating iNO, ventricular geometry, and provocative testing improves concordance between hemodynamic classification and clinically integrated phenotype assignment. Clinical Perspective What Is New? In the deeply phenotyped PVDOMICS cohort, resting pulmonary capillary wedge pressure demonstrated good overall discrimination for adjudicated Group 2 (left heart disease) pulmonary hypertension, yet intermediate values frequently either concealed latent left-heart disease or overclassified patients without intrinsic left-heart disease Resting pulmonary capillary wedge pressure should be viewed as a continuous probability signal rather than a binary threshold, allowing additional physiologic testing to be targeted according to the degree of diagnostic uncertainty a clinician is willing to accept. A staged physiology-guided approach incorporating inhaled nitric oxide, ventricular geometry, and provocative testing improved concordance with adjudicated PH category and pre or post-capillary classification. What Are the Clinical Implications? Pre- versus post-capillary classification should be interpreted within the broader clinical and physiologic context rather than relying on a single resting pulmonary capillary wedge pressure threshold. Intermediate pulmonary capillary wedge pressure values should prompt consideration of additional physiologic evaluation, with inhaled nitric oxide providing a practical intermediate step and provocative testing providing the greatest incremental diagnostic yield. Exercise pulmonary capillary wedge pressure/cardiac output slope and markers of ventricular interdependence may provide complementary information for resolving uncertainty when resting and dynamic hemodynamics are discordant.

Background Invasive micropapillary carcinoma (IMPC) of the breast is associated with a high propensity for lymphovascular invasion and lymph node metastasis. However, whether chemotherapy is associated with improved survival outcomes in these patients remains unclear. Methods This retrospective study analyzed IMPC patients from the SEER database (2010–2018) (n=1,150) and an external validation cohort from Nanjing Drum Tower Hospital (n=199). Propensity score matching assessed chemotherapy’s impact on overall survival (OS) and breast cancer-specific survival (BCSS) in the SEER cohort. A risk stratification model was developed and validated using the external cohort. Results In the SEER cohort, chemotherapy was associated with significantly improved OS (HR = 0.517, 95% CI 0.293-0.910, P = 0.020) but not BCSS. A risk model incorporating marital status, tumor size, subtype, and radiotherapy history identified high- and low-risk groups. Chemotherapy was associated with significantly better OS only for high-risk patients (internal training cohort: HR = 0.577, 95% CI 0.349-0.952, P = 0.029; internal validation cohort: HR = 0.213, 95% CI 0.070-0.647, P = 0.003). External validation consistently confirmed poorer prognosis for high-risk patients (HR = 2.969, 95% CI 1.028-8.571, P = 0.035) and verified the model’s ability to identify patients with differential OS associations with chemotherapy: chemotherapy was associated with better OS in high-risk patients (HR = 0.163, 95% CI 0.031-0.868, P = 0.016), but not in low-risk patients (HR = 0.793, 95% CI 0.153-4.103, P = 0.782). Conclusions Chemotherapy was associated with improved prognosis particularly in high-risk patients with IMPC. However, chemotherapy decisions should be made cautiously for low-risk patients, taking into account a comprehensive assessment of clinical and pathological factors.

INTRODUCTION: Alcohol-associated hepatitis (AH) is a severe condition with high short-term mortality. Identifying key predictors of poor outcomes is critical for guiding therapeutic strategies. Mean arterial pressure (MAP), a key determinant of tissue perfusion and systemic hemodynamics, may play a pivotal role in prognosis. METHODS: We analyzed a multicenter, prospective cohort of 323 patients hospitalized with AH, with validation in an independent cohort of 290 patients. Survival was evaluated using Kaplan-Meier curves and compared with the log-rank (Mantel-Cox) test. Cox proportional hazards models were used to estimate hazard ratios for mortality, adjusted for Model for end stage liver disease score. Mechanistic insights were explored through assessment of cardiovascular biomarkers. RESULTS: A baseline MAP <80 mm Hg was associated with significantly higher mortality at both 28 days (27.3% vs 8.0%) and 90 days (40.3% vs 15.6%; P < 0.001 for both). This association persisted after adjusting for Model for end stage liver disease score, age, and baseline hepatic encephalopathy. The incidence of infections during follow-up was similar across MAP groups (27.6% vs 22.8%), but acute kidney injury occurred more frequently in the MAP <80 mm Hg group (62% vs 38%, P < 0.001). In the validation cohort, patients with MAP <80 mm Hg also demonstrated significantly lower 28-day transplant-free survival. Although B-type natriuretic peptide and plasma renin levels were altered in patients with AH, they did not correlate with MAP values. DISCUSSION: A baseline MAP <80 mm Hg is an independent predictor of short-term and mid-term mortality in patients with AH. Strategies aimed at restoring hemodynamic stability may improve outcomes in this high-risk population.

TPS650 Background: The TAILORx and RxPONDER trials showed that recurrence score (RS) identifies many postmenopausal pts who do not benefit from addition of ACT to endocrine therapy (ET); however, RS also identifies subsets who do benefit (node-neg/high clinical risk/RS 16-20, node-neg/RS 21-25, and node-pos/RS ≤25). Most premenopausal pts in these trials did not receive ovarian function suppression (OFS) as part of their ET regimen. Given the observed benefit from OFS in high-risk premenopausal pts with HR+/HER2– BC in SOFT/TEXT, we question whether the ACT benefit in TAILORx/RxPONDER was due to chemotherapy-induced OFS. To address this, we developed OFSET, a phase III clinical trial comparing OFS+ET to ACT+OFS+ET. Methods: We hypothesize that addition of ACT to OFS+ET is superior to OFS+ET in improving invasive breast cancer-free survival (IBCFS) among premenopausal pts with early-stage HR+/HER2– tumors, and a 21-gene RS between 16-25 (for pN0 pts) and 0-25 (for pN1 pts). Secondary objectives include invasive disease-free survival, overall survival, distant recurrence-free interval, breast cancer-free interval, and health-related quality of life (HRQOL). Pts must be node-neg with RS 16-20 (plus high clinical risk), RS 21-25, or have 1-3 positive nodes with RS ≤25. Stratification is by nodal status/RS status (pN0 RS 16-25; pN1 RS 0-15; pN1 RS 16-25), intent to receive CDK4/6 inhibitor (yes; no), and age (18-39; ≥40). Pts are randomized after surgery to either OFS+ET or ACT+OFS+ET. ET is an aromatase inhibitor (AI) per physician discretion; or tamoxifen if AI is not tolerated or if OFS is incomplete. Radiotherapy will be administered per protocol guidelines. An HRQOL sub-study will assess severe menopausal symptoms (measured by FACT ESS-19) and pain severity (PROMIS) between arms. Blood and tumor specimens will be collected for future research. We anticipate accrual of 3,960 pts in 7 yrs, 7 mos. Per NSABP B-28/RxPONDER data, 5-yr IBCFS of pN1 pts on the ACT+OFS+ET arm is estimated at 92.3%. Per TAILORx data, 5-yr IBCFS of pN0 pts on the ACT arm is ~95%. Assuming 56% of pts to be pN0 and 44% pN1, and a 0.5% annual loss-to-follow-up rate, the definitive analyses to detect a hazard ratio: 0.75 with ACT+OFS+ET v OFS+ET, with 1-sided α of 0.025 and 80% power, will require 380 IBCFS events, expected to occur ~11 yrs after study initiation. Accrual is 496/3,960 (from 8/2023 to 1/2026). NCT #: NCT05879926. Clinical trial information: NCT05879926 .

e16535 Background: RMC is a rare and highly aggressive malignancy that predominantly affects young individuals with sickle hemoglobinopathies. Due to its rarity, no validated prognostic models exist to guide clinical decision-making. We aimed to develop and internally validate a prognostic model for patients with RMC using routinely available clinical and laboratory variables. Methods: We analyzed a single-institution cohort of patients with RMC. Candidate variables were identified based on biological plausibility and represented in a directed acyclic graph. Missing data were handled via multiple imputation by chained equations ( m = 50). Variables were ranked using elastic net Cox regression ( α = 0.5, λ = λ min ) with stability selection derived from 100 bootstrap resamples per imputed dataset. Predictors achieving > 60% selection frequency were retained for a nested parsimony analysis. Bootstrap internal validation ( B = 2000) estimated optimism-corrected discrimination and calibration performance, with the calibration slope applied as global shrinkage to penalize final coefficients for overfitting. Clinical utility was evaluated via decision curve analysis (DCA) at 18- and 24-month horizons. Results: Among 180 patients (median age 29; IQR 23–37), 142 deaths occurred with a median follow-up of 12.4 months. The final model included four predictors (Table). The optimism-corrected c-index was 0.667 (optimism = 0.009), and the calibration slope was 0.964, indicating minimal overfitting. Calibration plots showed excellent predicted-observed agreement at 12, 18, 24, and 36 months. DCA showed net benefit across threshold probabilities of 10%–75% at 18 months and 10%–80% at 24 months compared to default strategies. In sensitivity analysis, inclusion of TP53 mutation status improved discrimination ( c -index 0.686) and model fit ( ΔAIC −10.6). An interactive web-based risk calculator was developed to facilitate clinical implementation. Conclusions: This study presents the first internally validated prognostic model for RMC, demonstrating acceptable discrimination and excellent calibration using routinely available variables. By stratifying patients into distinct risk groups, this model may inform treatment intensity—guiding escalation to multi-agent regimens or sequential chemotherapy cycling in high-risk patients, while identifying lower-risk patients who may benefit from de-escalation strategies such as metastasis-directed therapy for oligometastatic disease or consideration of cytoreductive nephrectomy. External validation is warranted. Variable Time Ratio 95% CI p value ECOG performance status 0.64 0.53–0.77 <0.001 Distal (non-retroperitoneal) lymph node metastases 0.69 0.52–0.92 0.011 Neutrophil-to-lymphocyte ratio 0.98 0.94–1.02 0.25 Corrected calcium (mg/dL) 0.77 0.56–1.06 0.10 Sensitivity Analysis Only TP53 Mutation 0.63 0.36-1-10 0.10

e15060 Background: In metastatic Breast Cancer (mBC) Circulating Tumor Cells (CTCs) are an established prognostic indicator of patients (pts) with highly aggressive disease, poor clinical outcomes, and poor response rates to therapy. However, CTCs are typically found in < 20% of mBC pts and many pts without CTCs also progress. Cancer associated macrophage-like cells (CAMLs) are inflammatory tumor macrophages also found in blood, in > 90% of mBC, and are indicators of poor clinical outcomes independent of CTCs. We conducted a prospective study to model CTC & CAML subtypes from 212 mBC pt blood samples prior to induction of new systemic therapies to optimize and validate risk models based on 2-year outcomes of Progression-free survival (PFS) & Overall survival (OS). Methods: An observational multi-institutional prospective study was conducted on 212 mBC pts prior to induction of a new line of therapy who were progressing on their current therapy. Anonymized (7.5ml) whole blood samples were taken prior to therapy induction and filtered by CellSieve filtration. Quantities and subtypes of CTCs & CAMLs were categorized by their expression of CK+/CD45+/CD14+ for CAMLs and CK+/CD45-/CD14- for CTCs. PFS (RECIST v1.1) and OS hazard ratios (HRs) were calculated by censored univariate & multivariate analysis at 2 years. Results: Pt median age was 51 years (range 25-92); TNBC (44%), ER/PR+ (30%), HER2+ (15%). Pts were treated with chemotherapy alone (18%), immune checkpoint inhibitor (46%), targeted (40%), hormone (8%) and unknown (5%). 38% (81/212) pts had ≥1 CTCs which correlated with significantly poorer PFS (HR = 1.9; 95%CI 1.3-2.7; p = 0.0016) and OS (HR = 2.0; 95%CI, 1.3-3.0; p = 00025), with the most significant risk at ≥8 CTCs (14% pts), PFS (HR = 3.8; 95%CI, 2.1-6.9; p < 0.0001) and OS (HR = 7.2; 95% CI, 3.4-14.9; p < 0.0001). Independently, 93% (n = 196/212) of pts had ≥1 CAML, with a threshold of >40um size (84% pts) had significantly poorer PFS (HR = 2.0; 95% CI, 1.2-3.1; p = 0.0032), but not OS (HR = 1.5; 95%CI, 0.9-2.7; p = 0.1169). However, a threshold of >125um size CAML (43% pts) also had significantly poorer PFS (HR = 1.8; 95% CI, 1.2-2.7; p = 0.0013) and OS (HR = 1.6; 95% CI, 1.0-2.5; p = 0.0233). By combining models, the best outcomes were seen in pts with 0 CTCs & 0 CAMLs (mPFS = 12.6 & mOS = 21.3), followed by 0 CTCs & ≥40um CAMLs (mPFS = 5.2 & mOS = 17.5) and 0 CTCs & ≥125um CAMLs (mPFS = 4.9 & mOS = 15.2). Poorer outcomes were seen with ≥1 CTCs (mPFS = 3.3 & mOS = 13.5) and the worst outcomes with ≥8 CTCs (mPFS = 2.5 & mOS = 4.8). Conclusions: CTCs were uncommon in mBC pts but correlated with very poor clinical outcomes. In parallel analysis, CAMLs were common with CAML size correlating with increasingly poorer outcomes. By combining CTC & CAML subtypes, mBC pts were more accurately stratified by risk of progression and death. Additional multivariate studies correlating treatment class and tumor response rates are ongoing.

e14535 Background: Anti-programmed cell death ligand PD-L1/PD-1 immune checkpoint inhibitors (ICIs) are approved for metastatic breast cancer (mBC) patients (pts) with a tumor combined positive score (CPS) ≥10% in their tissue. However, many pts with < 10% CPS may also respond to ICIs. Recent studies in lung cancer have shown that circulating tumor cells (CTCs) and tumor-macrophage fusion cells (TMFCs) both express, and may upregulate, PD-L1 which is predictive for ICI responses. We initiated a prospective study to monitor PD-L1 in CTCs & TMFCs in mBC pts prior to receiving systemic ICIs to correlate their PD-L1 expression to progression free survival (PFS) and overall survival (OS) at 24 months. Methods: We conducted a multi-institutional prospective pilot study of n = 102 pts with pathologically confirmed mBC, having failed ≥1 prior lines of therapy, prior to receiving ICIs (n = 52 Pembrolizumab, n = 39 Retifanlimab, n = 5 Atezolizumab, and n = 1 Nivolumab). Anonymized blinded peripheral blood samples (7.5ml) were procured prior to ICI induction (T0) and (~40 days after ICI induction (T1). TMFCs & CTCs were isolated using Cellsieve microfilters with average PD-L1 expressions measured then categorized as negative/low or high. Tumor CPS was categorized as negative/low (< 10%) or high (> 10%). We compared TMFC PD-L1 to tissue CPS by linear regression. TMFC/CTC PD-L1 expression and tissue PD-L1 CPS were compared to pts’ PFS and OS by Cox proportional univariate and multivariate analysis over 24 months. Results: Of n = 102 pts, median age = 59 years (range 32-77); 42% (43/102) were ER+, 33% (33/102) were PR+, 5% (5/102) were HER2+, and 56% (57/102) were triple-negative. 32% (32/102) had an ECOG score of 0, 25% (26/102) had ECOG 1, and 43% of scores were unavailable. N = 42 pts had available tumor CPS data, which did not correlate to TMFC/CTC PD-L1 at T0 or T1. Pts with high CPS did not significantly predict for PFS (HR = 0.78; 95% CI, 0.3-1.9; P = 0.7627) nor OS (HR = 0.54; 95% CI, 0.2-1.7; P = 0.4471). Pts with high TMFC/CTC PD-L1 at T0 also did not significantly predict for PFS (HR = 0.74; 95% CI, 0.5-1.2; P = 0.2799) nor OS (HR = 0.84; 95% CI, 0.4-1.6; P = 0.7220). However, of the n = 82 pts who provided T1 samples, high CTC/TMFC PD-L1 at T1 was significant for better PFS (HR = 2.55; 95% CI, 1.6-4.2; P = 0.0004) and better OS (HR = 2.06; 95%CI, 1.1-3.8; P = 0.0309). Conclusions: In this study of mBC pts treated with PD-L1 ICIs, tissue CPS did not correlate with PD-L1 expression in CTCs or TMFCs. Further, neither CPS nor baseline PD-L1 in CTC/TMFCs predicted for clinical outcomes in ICI therapies. However, PD-L1 in CTC/TMFCs ~40 days post-induction of ICI did predict for better response rates. While this study suggests predictive value of monitoring PD-L1 in blood during ICI therapies, further studies are required to refine and validate these findings.