Citations

Summary Rosai–Dorfman disease (RDD) is a rare histiocytic neoplasm with diverse clinical behaviour and immune abnormalities with unknown clinical significance. We performed a retrospective cohort study of 162 patients with RDD from 2003 to 2025 at five international referral centres. Median age was 48 years and 64.8% were female. Multisystem disease occurred in 87 patients (53.7%), commonly involving skin/subcutaneous tissue (49.4%), lymph nodes (39.5%) and bones (34%). Molecular testing was available for 102 patients; 40 (39.2%) were mitogen‐activated protein kinase/rat sarcoma virus oncogene homolog signaling pathway (MAPK/RAS)‐altered, commonly with kirsten rat sarcoma viral oncogene homolog ( KRAS ) or mitogen‐activated protein kinase 1 ( MAP2K/MEK ) alterations. MAPK/RAS alterations were associated with multisystem disease ( p = 0.0034). Autoimmune disease (AID) was documented in 29 patients (17.9%), usually preceding RDD, and 45/95 patients (47.4%) with available autoantibody status had at least one positive autoantibody. Among 153 patients with response data, objective response occurred in 94 (61.4%). Response distribution differed by disease extent; single‐system disease was associated with more complete responses and less progression than multisystem disease. At a median follow‐up of 2.49 years, eight deaths occurred; 5‐year overall survival was 93.4%. AID and autoantibody positivity were not associated with response or overall survival. These findings support disease extent and molecular status as clinically relevant dimensions of RDD assessment, while autoimmune and serological abnormalities should be interpreted in clinical context.

PURPOSE Patients with breast cancer requiring postmastectomy radiation therapy (PMRT) often desire breast reconstruction. Reconstructions can be adversely affected by PMRT, and fear of reconstruction complications has discouraged adoption of short-course radiation therapy used after lumpectomy. To fill the evidence gap, we conducted a noninferiority trial of hypofractionated versus conventional PMRT in patients undergoing breast reconstruction. The primary outcome was reconstruction complication rate, a composite of wound healing, readmission, capsular contracture, unplanned reoperation, and reconstruction failure. METHODS Women with unilateral invasive breast cancer with planned immediate or delayed reconstruction and PMRT were randomly assigned (1:1) to 50 Gy (25 fractions/5 weeks) or 42.56 Gy (16 fractions/3 weeks). This study was designed with a noninferiority margin of 10%, assuming a 2-year reconstruction complication rate of 25% with conventional PMRT. Randomization was stratified by immediate versus delayed and autologous versus implant-only reconstruction. RESULTS Between 2018 and 2021, 898 patients enrolled with a median follow-up of 3.9 years; 825 patients were evaluable for the primary end point. The 24-month reconstruction complication rates were 12.3% (52/422) with hypofractionated PMRT and 10.2% (41/403) with conventional PMRT, corresponding to an estimated difference of -2.1% (95% CI, -6.5 to 2.2). The complication rate was higher (regardless of arm) with implant-only versus autologous reconstruction (odds ratio = 1.65). There was no statistically significant difference in 36-month locoregional recurrence rates: 1.5% (95% CI, 0.7 to 3.2) with hypofractionated and 2.2% (95% CI, 1.1 to 4.3) with conventional PMRT. Acute and late toxicity rates were not statistically different. CONCLUSION A 16-fraction course of hypofractionated PMRT is safe and noninferior to conventional PMRT in women undergoing breast reconstruction after mastectomy.

The bone marrow immune microenvironment (BMME) is a critical factor in multiple myeloma (MM) pathogenesis. Despite higher incidence of MM among self-identified African Americans, the relationship between African genetic similarity and the BMME remains unclear. We present the largest analysis to date assessing the impact of Ancestry on the BMME in myeloma (N=320, including 64 with ≥50% African genetic similarity, AFR-High) leveraging our recently generated Immune Atlas. AFR-High was associated with enrichment of late T-effector cells, driven by rare cytotoxic CD4⁺ T cells, suggesting a distinct adaptive BMME. AFR-High exhibited expansion of late-differentiated adaptive NK cells with high cytotoxic GNLY and GZMH expression. AFR-High depicted reduced CD14⁺ monocytes, increased CD16⁺ non-classical monocytes, and expansion of macrophage-like monocyte populations with enrichment of metabolic adaptation, efferocytosis and phagocytic clearance programs, and immunoregulatory pathways. These findings reveal a shift from an innate inflammatory immune landscape toward adaptive cytotoxic and immunoregulatory remodeling associated with African genetic similarity in MM.

Gut wall physiology in multiple sclerosis (MS) and autoimmune neurologic diseases remains underexplored. This review examines gut wall dysfunctions’ contribution to MS and autoimmune neurological disorder pathogenesis and progression. We discuss 3 inter‐related aspects of gut physiology: intestinal barrier, enteric nervous system (ENS), and mucosal immunity. We highlight the ENS as a putative target of immune injury in selected antibody‐mediated and T cell‐associated neurologic diseases. Finally, we propose a unifying framework in which the gut functions as a site of immune priming and target of autoimmune injury, bridging microbiome‐driven mechanisms in MS with ENS‐directed autoimmunity across neurologic diseases. ANN NEUROL 2026

Abstract Pancreatic ductal adenocarcinoma (PDAC), the most common subtype of pancreatic cancer, is a deadly disease with a complex tumor microenvironment (TME). Cytotoxic combination chemotherapy treatments are the mainstay of PDAC therapy, but patients rapidly develop chemoresistance, highlighting the need to elucidate how chemotherapy alters the TME and whether these changes drive chemoresistance. Here, we examined matched pre- and post-treatment tissue specimens using single-cell RNA-sequencing and found near-universal enrichment after treatment of axonal guidance genes in cancer-associated fibroblasts (CAFs). These neural CAFs were enriched near sites of perineural invasion, coinciding with regions of increased tumor cell proliferation, and were enriched in tumor areas distant from nerves after chemotherapy. Metastatic recurrent lesions had the highest prevalence of neural CAFs versus primary tumors and untreated metastases. Neural CAFs showed elevated non-canonical WNT mediators and axonal guidance genes, which complemented matching cognate binding partners in tumor epithelial cells, suggesting a role in tumor-stroma crosstalk. Additionally, in vitro studies revealed enrichment of axonal guidance genes in patient-derived CAF lines upon exposure to chemotherapy or tumor cells. Altogether, these findings implicate fibroblast-derived axonal-guidance genes in promoting PDAC invasion and point to a promising therapeutic target for this disease.

Abstract Therapeutic resistance in ovarian cancer is frequently driven by persistent replication stress, yet the molecular mechanisms that convert replication stress into a therapeutically exploitable vulnerability remain incompletely understood. Here, we identify drug-induced nuclear cathepsin L (nCTSL) as a previously unrecognized regulator of replication stress and DNA repair. Clofarabine (CLF) combined with the ATR inhibitor AZD6738, or the CHK1 inhibitor prexasertib promoted nuclear accumulation of CTSL, where it remodeled the replication machinery through degradation of CCNE1, MCM3, MCM6, and geminin, accompanied by loss of RAD51 and 53BP1 and increased γH2AX and phospho-RPA2. DNA fiber analysis demonstrated marked inhibition of replication fork progression following CLF-based combinations, whereas CTSL depletion accelerated fork progression and abolished therapy-induced replication stress. Reconstitution with the nuclear M1F CTSL isoform restored replication restraint, confirming a direct role for nuclear CTSL in regulating replication dynamics. GFP-based DNA repair reporter assays further revealed that CLF-based combinations suppress DNA repair competence in a CTSL-dependent manner, indicating that nuclear CTSL couples replication stress amplification with functional inhibition of repair pathways. Functionally, CLF-based combinations selectively targeted transformed fallopian tube secretory epithelial cells while sparing non-transformed counterparts, demonstrated broad activity in patient-derived ovarian cancer ascites spheroids, and significantly inhibited tumor growth and prolonged survival in vivo . Collectively, our findings identify nuclear CTSL as a mechanistic driver of replication stress that remodels the replication machinery, impairs DNA repair, and creates a therapeutically exploitable vulnerability in ovarian cancer. We propose that nuclear CTSL promotes a transition from replication competence to replication catastrophe, thereby establishing a conceptual framework for biomarker-guided therapeutic strategies targeting CTSL-dependent replication stress.

ABSTRACT Background Family history of pancreatic cancer (PC), pathogenic germline variants (PGVs), and increased intrapancreatic fat (IPF) are individually associated with increased PC risk. Whether IPF is elevated in high‐risk individuals (HRIs) with PC family history or PGVs is unknown. Although MRI is the preferred modality for IPF measurement, region‐of‐interest–based approaches are prone to sampling bias because pancreatic fat is heterogeneously distributed. We aimed to compare IPF among HRIs and matched non‐HRI controls using an Artificial intelligence (AI)‐based tool for whole pancreatic IPF measurement applied to magnetic resonance imaging (MRI). Methods We developed and validated a deep‐learning pipeline for IPF measurement that incorporates automated pancreas segmentation on T1‐weighted MRI images registered to the corresponding iterative decomposition of water and fat with echo asymmetry and least squares estimation images to compute IPF using proton density fat fraction (PDFF). This pipeline was used to quantify IPF and assess IPF distribution patterns in 85 HRIs and 170 non‐HRIs matched 1:2 for age, sex, BMI, and diabetes status. A surface erosion approach was developed to minimize the impact of peripancreatic fat on IPF measurement. Linear models adjusting for matching variables were used to assess associations. Results Model‐expert agreement for whole‐pancreas PDFF was excellent (intraclass correlation coefficient 0.99; 95% CI, 0.98–0.99 mean absolute error 1.4%). Mean PDFF did not differ between HRIs and controls (25.8% [11.5] vs. 26.9% [11.4]; p = 0.32). PDFF increased with age ( p = 0.015), male sex ( p < 0.001), presence of diabetes ( p = 0.009), BMI ( p < 0.001). IPF distribution patterns did not differ by risk group. Conclusion An AI‐based approach provides accurate, scalable, and objective assessment of IPF quantity and distribution. IPF quantity and spatial distribution do not appear to differ based on germline or familial predisposition to PC.

Purpose Radioligand therapy (RLT) with [ 177 Lu] Lu-PSMA-617 has shown significant benefits in metastatic castration-resistant prostate cancer (mCRPC), including prolonged overall survival (OS) and progression-free survival (PFS), as well as improved quality of life. For patients previously treated with [ 177 Lu]Lu-PSMA-617 who subsequently experience disease progression, retreatment with [ 177 Lu] Lu-PSMA-617 has emerged as a potential approach, yet data on the outcomes of RLT retreatment remains limited. This study aimed to assess the efficacy and safety of retreatment RLT in mCRPC. Methods Clinical and imaging data of patients who underwent at least two cycles of [ 177 Lu] Lu-PSMA-617, followed by a second course of treatment with [ 177 Lu] Lu-PSMA-617 between March 2018 and December 2024, were retrospectively reviewed. Endpoints included biochemical response, imaging response, toxicity, PSA-PFS, rPFS, and OS. Radiologic and biochemical responses were evaluated using RECIST 1.1 criteria and PSA levels, respectively. Results A total of 589 patients underwent [ 177 Lu] Lu-PSMA-617 RLT, of whom 20 (3.4%, 20/589) received RLT retreatment. The median age was 71.3 years (range: 63.7–95.2), and the median follow-up was 73.3 months (95% CI, 35.7–77.2 months) after the initial treatment and 21.7 months (95% CI, 16.9–26.0 months) after retreatment. The initial treatment involved a median of 4.5 cycles (range: 2–6). Following the first course of RLT, 15 patients (75%, 15/20) had exhibited a &gt;50% decline in PSA levels, including 9 who achieved a &gt;90% decrease. Additionally, 12 patients (60%, 12/20) had demonstrated a complete or partial imaging response, while 3 (15%, 3/20) patients had stable disease, and 5 (25%, 5/20) patients had progressive radiologic disease. Patients received a median of 4 retreatment cycles (range, 1–6), and the median interval between initial RLT and retreatment RLT was 33.1 months (IQR, 16.2–48.9 months; range, 10.7–58.8 months). A PSA decline of ≥50% was observed in 9 out of 20 patients (45%, 9/20). An imaging response was observed in 10 patients (50%, 10/20), with 4 achieving a complete response and 6 achieving a partial response, whereas 10 patients (50%, 10/20) showed progression. The median PSA-PFS was 9.8 months (95% CI, 4.1–17.9 months), and the median rPFS was 8.2 months (95% CI, 3.3–17.9 months). Eight deaths occurred during follow-up. The estimated Kaplan Meier OS rates were 83.6% at 12 months (95% CI, 57.3%–94.4%) and 53.7% at 24 months (95% CI, 28.3%–73.7%). Grade 2 renal toxicity was observed in one patient (5%, 1/20). Three patients (15%, 3/20) developed Grade 2 anemia. Notably, no grade 3 or grade 4 adverse events were observed during either treatment period. Conclusion In our cohort, retreatment with [¹ 77 Lu]Lu-PSMA-617 RLT was associated with biochemical and imaging responses in some patients, with observed survival outcomes that support further investigation. However, given the retrospective single-arm design and small sample size, large prospective studies are needed to more rigorously evaluate the safety, efficacy, and optimal patient selection for retreatment RLT.