Citations

Abstract Background Characterization of transplant transmitted infections associated with drowned organ donors and the recipients is not well delineated, posing challenges for optimal management and prophylaxis strategies. Broader organ sharing may pose additional considerations due to pathogen variation. Methods We reviewed 22 potential donor disease transmission events (PDDTEs) from drowned donors reported to the Organ Procurement and Transplantation Network (OPTN) ad hoc Disease Transmission Advisory Committee (DTAC) from 2017-2022 to estimate the incidence of PDDTEs among all US drowned organ donors and identify the most common pathogens in this setting. We also characterized donor/recipient epidemiology, infection timing and risk factors, and recipient survival. Results From 2017-2022, drowning was the mechanism of death in 777/74,232 (1.0%) of all US organ donors, from whom 2500 organs were transplanted. Among the 22 PDDTEs, there were 70 organ recipients. The median donor age was 17.5 years (range 1-70 years) and lung recipients accounted for 5/70 organ recipients. All PDDTE reports were submitted due to recipient disease, and index cases occurred 2-19 days post-transplant. 7/22 (7/777 drowned donors, 0.9%) PDDTEs were associated with pathogens consistent with plausible waterborne transmission, of which 4 were due to invasive molds (Zygomycetes and Scedosporium) and 3 were due to bacteria (Pseudomonas and Legionella). Of the 21 organ recipients from these 7 donors, 8 had proven or probable infections. 6/8 recipients had severe infection with 3 deaths, all from invasive mold infections. There were no identifiable infection risk factors related to drowning water source, donor immersion time, or geographic region. However, donor/recipient regional discordance occurred in 5/21 recipients, demonstrating the trend in broader organ sharing. Conclusion Though rare, organ recipients are at risk for transplant transmitted infection from drowned donors, particularly invasive mold infections. All infections occurred within the first month after transplant with high associated mortality. Though optimal management and prophylaxis strategies in these scenarios remain uncertain, post-transplant vigilance for early infection is paramount. Disclosures Helen S. Te, MD, CVS Caremark: Advisor/Consultant Lara A. Danziger-Isakov, MD, MPH, Aicuris: clinical research contract, paid to institutio|Ansun BioPharma: clinical research contract, paid to institution|Astellas: Advisor/Consultant|Astellas: clinical research contract, paid to institutio|Merck: clinical research contract, paid to institutio|Pfizer: Grant/Research Support|Takeda: clinical research contract, paid to institutio Anil J. Trindade, MD, CareDx, Inc.: Advisor/Consultant|CareDx, Inc.: Grant/Research Support|TFF Pharmaceuticals: Advisor/Consultant|Veloxis Pharmaceuticals, Inc.: Grant/Research Support

Abstract Background Staphylococcus lugdunensis (SL) is a coagulase-negative staphylococcus with virulence comparable to that of Staphylococcus aureus. The “skip phenomenon” (SP) is a pattern where blood cultures are intermittently negative before final clearance of bloodstream infection (BSI). SP is well-documented in S. aureus bacteremia but has not been described previously in SL. In this report, we present a cohort with SL BSI and describe its prevalence and their clinical features and outcomes. Methods We conducted a retrospective review of patients with blood cultures positive for SL in samples referred to the Mayo Clinic reference lab between June 2012 and June 2022. We assessed clinical characteristics, including time to positivity, prevalence of the skip phenomenon (defined by a positive culture after 24 hours of negative cultures), patient demographics including Charlson Comorbidity Index, mortality and length of hospital stay. Results We identified 55 patients with SL BSI and 33 of them had enough laboratory data to determine the prevalence of the skip phenomenon. SP was present in 5 of 33 (15.2%) patients. For all patients with SL BSI, the median age was 67 years (interquartile range [IQR] 61-79); mean CCI in the group with SP was 5.6 (standard deviation 2) and those without SP was 5.9 (standard deviation 2.7); median duration of bacteremia was 3 days (IQR 1-4); median hospital length of stay was 14 days (IQR 8-20); and 1-year mortality was 45%. Oxacillin susceptibility was present in 33 of 34 cases. Conclusion A total of 15% of patient cases with SL BSI demonstrated the SP. Recognition of the SP in patients with SL BSI is important as this may impact duration of antibiotic therapy and timing of long-term cardiovascular device placement. Disclosures Larry M. Baddour, MD, UpToDate, Inc.: Royalty payments (authorship duties).

5 Background: Metastatic anal squamous cell carcinoma is rare and associated with a poor prognosis. There is limited evidence on the impact of local interventions on survival outcomes in patients with metastatic disease. We aimed to evaluate the survival of patients with liver-only metastatic anal cancer following definitive local management of liver lesions. Methods: This is a single-institution retrospective cohort study of patients with liver-limited metastatic anal cancer who underwent curative-intent local therapy. Clinical characteristics were collected and analyzed. The Kaplan-Meier method was used to calculate disease-free survival (DFS) and overall survival (OS). Prognostic factors associated with DFS and OS were assessed using Cox-proportional hazards models. Results: Twenty-five patients were included, median age was 59 years, and 92% were female. None of the patients had known HIV infection, 92% had HPV-positive disease and 76% had metachronous liver metastases following locoregional disease. All patients received chemoradiation for the primary lesion Unilobar hepatic involvement was present in 76% of the patients, with 56% having a single metastatic lesion. Pre-intervention systemic therapy was provided to 52% of the patients, including 8 who received carboplatin and paclitaxel, with a median duration of 3 months and ORR of 69%. Definitive treatment of metastatic disease included surgical resection (60%), non-surgical interventions (20%), and multimodal therapy (20%). All patients had viable tumor in the pathological specimen. With a median follow-up of 22 months, median DFS was 7.3 months, and median OS was 51.3 months. An ECOG performance status of 2, poorly differentiated histology, and extrahepatic recurrence were identified as significant prognostic factors in the univariate analysis, but not in the multivariate analysis. Conclusions: Our results demonstrate potential for long-term survival in liver-limited metastatic anal squamous cell carcinoma amenable to local therapeutic intervention combined with systemic therapy. These findings warrant further prospective study of local therapy in oligometastatic anal cancer. Characteristics N=25 (%) Median number of liver metastases (range), lesions- 1- 2-3- >3 1 (1-20)14 (56)8 (32)3 (12) Median maximal diameter of liver metastases (range), cm 3 (0.9-11.9) Best response of liver metastases to chemotherapy (N=13)- Complete response- Partial response- Stable disease- Progressive disease 2 (15)7 (54)3 (23)1 (8) Surgical procedure (N=20)- Right/left hemi-hepatectomy- Segmentectomy- Wedge resection 4 (20)14 (70)2 (10) Non-surgical procedure (N=10)- Local ablation- Radiotherapy- Other 5 (50)3 (30)2 (20) Hepatic surgical margins (N=20)- Positive margins- Close margins (<1mm)- Negative margins 02 (10)18 (90) Recurrent disease- Yeso Intrahepatico Extrahepatic- No 20 (80)14 (70)6 (30)5 (20)

766 Background: BASECAMP-1 (NCT04981119) is a pre-screening study to identify patients with tumor-associated human leukocyte antigen (HLA)-A*02 loss of heterozygosity (LOH) for interventional studies, such as EVEREST-2 (NCT06051695), a phase 1/2 study of logic-gated chimeric antigen receptor T-cell (CAR T) therapy for MSLN-expressing cancers. MSLN is a cell surface protein expressed in several cancer types, including mesothelioma (MESO), colorectal (CRC), non-small cell lung (NSCLC), ovarian (OVCA), and pancreatic (PANC) cancer, which can be associated with poor prognosis (1). Longitudinal clinical, genomic, and biomarker data were collected from patients enrolled in BASECAMP-1, providing a large dataset for translational discovery and propensity scoring. The aim of this analysis was to determine whether MSLN expression measured by RNAseq and IHC are correlated among patients with solid tumors. Methods: In BASECAMP-1, tumor tissue from patients with germline heterozygous HLA-A*02 is tested for HLA-A*02 LOH using an investigational next generation sequencing device codeveloped with Tempus Labs (Lozac'hmeur, et al. NPJ Precis Oncol. 2024) that detects somatic alterations, including HLA LOH, and generates RNAseq data (eg, MSLN expression). Gene-level transcripts per million read (TPM) values were determined and the log2 TPM +1 was displayed in a scatter plot (the mean and standard deviation [SD] are provided in the Table). Patients with HLA-A*02 LOH also submit tissue for IHC testing for exploratory biomarkers (eg, MSLN expression using anti-MSLN clone 5B2). Statistical significance was determined with ANOVA or t-tests. Results: As of June 1, 2024, 314 patients had been screened for BASECAMP-1 and had RNAseq results; 34 patients also had MSLN IHC results. MSLN expression by RNAseq was consistently higher in patients with PANC or OVCA vs CRC or NSCLC ( P <0.001). MSLN expression by RNAseq and IHC were correlated overall ( P <0.001), particularly among patients with PANC and OVCA. Among the 8 patients with OVCA or PANC who were IHC+ for MSLN, only 1 had an RNAseq value below 6 log2 TPM+1; this patient had mesonephric-like ovarian adenocarcinoma, which may account for the low value. The one MESO sample with both RNAseq and IHC available was IHC+ and had a high RNAseq value. Conclusions: This analysis demonstrated high correlation between RNAseq and IHC MSLN expression in tumor tissue. 1. Faust, et al. Cancers. 2022. Clinical trial information: NCT04981119 . MSLN expression by RNASeq by tumor type and IHC status. Tumor Overall (N=314) IHC data available (n=34) MSLN Positive MSLN Negative n Mean TPM a (SD) n Mean TPM a (SD) n Mean TPM a (SD) All 314 5.1 (2.3) 20 6.0 (2.1) 14 2.3 (1.7) adNSCLC 33 3.8 (2.4) 2 4.7 (1.7) 7 1.5 (1.3) sqNSCLC 4 3.1 (1.8) 0 0 MESO 4 4.5 (4.2) 1 5.7 0 CRC 148 4.4 (2.0) 8 5.1 (2.1) 7 3.1 (1.6) PANC 100 6.1 (1.8) 3 7.8 (0.6) 0 OVCA 25 7.2 (2.1) 5 6.6 (2.8) 0 a MSLN log2 transcripts per million+1. ad, adenocarcinoma; sq, squamous.

TPS788 Background: MSLN is a desirable candidate for targeted therapy given its limited expression in normal tissues and its overexpression in several malignancies, including PANC, mesothelioma, non-small cell lung, and ovarian cancers (TCGA 2022). MSLN-targeted CAR T and T-cell receptor therapies have shown promising clinical activity; however, on-target, off-tumor toxicity, including fatal events, have occurred (1-3). Autologous logic-gated Tmod CAR T therapies address the challenges of on-target, off-tumor toxicity by combining 2 CARs: activating and blocking receptors. The activator recognizes a tumor-associated antigen present on the surface of both tumor and normal cells; the blocker prevents CAR T activity when it binds HLA-A*02, which is present in normal cells and often lost in tumor cells. Thus, in patients with tumor-associated HLA-A*02 LOH, the blocker prevents on-target, off-tumor toxicity on normal cells due to retained HLA-A*02 expression (4). HLA-A*02 LOH is observed in various solid tumors, including ~20% of PANC (5). Two autologous CAR T therapies are currently under investigation: A2B530, targeting carcinoembryonic antigen, in the EVEREST-1 trial, and A2B694, targeting MSLN, in the EVEREST-2 trial, described herein. A2B694 may provide a therapeutic window to treat patients with PANC and other MSLN-expressing solid tumors exhibiting HLA-A*02 LOH due to its unique discriminatory mechanism. Methods: EVEREST-2 (NCT06051695) is a first-in-human, phase 1/2, open-label, nonrandomized study to evaluate the safety and efficacy of A2B694 for recurrent unresectable, locally advanced, or metastatic cancers with MSLN expression, including PANC. Eligible patients must have exhausted options of potentially curative therapy and have recurrent disease. Enrollment to EVEREST-2 occurs through the prescreening study BASECAMP-1 (NCT04981119), in which patients with tumor-associated HLA-A*02 LOH are identified via next-generation sequencing (Tempus AI, Inc) and leukapheresis product is collected. A2B694 is manufactured from cryopreserved T cells when clinically appropriate for patients. The primary objective of phase 1 is to evaluate the safety and tolerability of A2B694 and identify the recommended phase 2 dose (RP2D). The dose-expansion phase will confirm RP2D and collect biomarker data to further characterize A2B694. Phase 2 will assess the primary endpoint overall response rate per RECIST v1.1 and secondary endpoints progression-free survival and overall survival. The first patient was dosed on April 24, 2024 and dose escalation is ongoing. 1. Beatty, et al. Gastroenterology . 2018. 2. Haas, et al. Mol Ther . 2023. 3. Hong, et al. ESMO 2021. Abstr 9590. 4. Hamburger, et al. Mol Immunol . 2020. 5. Hecht, et al. J Clin Oncol . 2022. Clinical trial information: NCT06051695 .

Abstract Background Adult onset medulloblastoma (aMB) is a rare tumor with limited available evidence. We present a large multi-institutional retrospective cohort of aMB patients treated in the modern era, with an emphasis on understanding the role of chemotherapy at initial diagnosis. Methods We included 267 consecutive patients with aMB treated at 7 different institutions from 2000-present, controlling for chemotherapy regimen and cycles received. Results Treatment factors were highly intercorrelated with one another and with treating institution. Concurrent chemotherapy was not associated with overall survival (OS). Adjuvant chemotherapy was associated with OS on univariable analyses (HR = 0.55, P = .029) and on multivariable analysis when adjusting for risk status (HR 0.55, P = .026) but not when also adjusting for treating institution. Proton craniospinal irradiation was associated with improved survival on univariable (HR = 0.50, P = .019) and multivariable analysis adjusting for risk status (HR = 0.51, P = .024) but not when treating institution was also considered. On subgroup analysis, adjuvant chemotherapy was associated with improved survival in M0 (HR = 0.55, P = .043) but not M1 disease, in patients with subtotal resection (HR = 0.43, P = .048) but not those with GTR. Similarly, progression-free survival was improved with chemotherapy in patients with M0 (HR = 0.57, P = .032) but not M1 disease, and in patients with subtotal (HR = 0.50, P = .054) but not gross total resection. Conclusions There was no benefit of concurrent chemotherapy. Adjuvant chemotherapy was associated with improved overall survival and this effect was driven by select subgroups, specifically those with M0 disease and those with residual tumor. We could not confirm that these associations are independent of the treating institution.

Objectives To evaluate the benefit of neoadjuvant chemotherapy (NAC) for patients with high‐risk upper tract urothelial carcinoma (UTUC) using a large, well‐curated multi‐institutional database. Patients and Methods This study was a multi‐institutional retrospective analysis conducted by the UTUC Collaborative Network (UCAN), combining data from 2276 patients with UTUC who underwent radical nephroureterectomy at seven high‐volume tertiary care centres in the United States. The UCAN data were analysed to evaluate the impact of response to NAC on survival outcomes in patients with UTUC. Results A total of 378 patients in the UCAN database underwent NAC. On final surgical pathology, 101 patients (26.8%) had ≤ypT1N0 disease and were defined as NAC treatment responders. Patients who responded to NAC had significantly longer overall survival (OS) and progression‐free survival (PFS) compared to non‐responders. At 5 years post‐surgery, 81.5% of responders were alive compared to 59.8% of non‐responders. The median OS and PFS times among non‐responders were 7.0 years (95% confidence interval [CI] 5.6–9.7) and 6.0 years (95% CI 4.6–9.3) respectively, while the median OS and PFS were not reached among responders. Limitations of this study include its retrospective design, heterogeneity in chemotherapy regimens, and the absence of clearly defined patient selection criteria for treatment. Conclusion These data suggest that NAC can play a pivotal role in the treatment of well‐selected UTUC patients who respond positively. Non‐responders had clearly inferior outcomes. More work is needed to find predictors of response which can improve patient selection.

Abstract Metals and metalloids including cobalt, gadolinium, lutetium, and germanium are used in numerous medical applications spanning diverse specialities including orthopedics, radiology, oncology, and healthcare artificial intelligence. These medical advances include cobalt containing orthopedic implants, gadolinium-based contrast agents, lutetium-containing cancer drugs, and germanium-based semiconductors. While these metal and metalloid-based solutions do improve patient care, there is a heavy side to how the elements needed for these solutions are mined, extracted, and discarded. These practices often exploit and harm vulnerable populations and environments. As healthcare professionals, we should be aware of the entire mineral to medicine lifecycle. As providers and consumers of these metal and metalloid-based solutions, we must advocate for more responsible and ethical extraction and recycling practices. As researchers and educators, we must promote and support continued research and development into less resource-intense medical solutions that can both improve patient care and sustainability.

Abstract Autoimmunity affects 10% of the population. Within this umbrella, autoantibody-mediated diseases targeting one autoantigen provide a unique opportunity to comprehensively understand the developmental pathway of disease-causing B cells and autoantibodies. While such autoreactivities are believed to be generated during germinal centre reactions, the roles of earlier immune checkpoints in autoantigen-specific B cell tolerance are poorly understood. We address this concept in patients with CASPR2-autoantibody encephalitis and healthy controls. In both groups, comparable and high (∼0.5%) frequencies of unmutated CASPR2-reactive naïve B cells were identified. By contrast, CASPR2-reactive memory B cells were exclusive to patients, and their B cell receptors demonstrated affinity-enhancing somatic mutations with heterogenous binding kinetics. These effector molecules possessed epitope-dependent pathogenic effects in vitro neuronal cultures and in vivo. The unmutated common ancestors of these memory B cells showed a distinctive balance between strong CASPR2 reactivity and very limited binding across the remaining human proteome. Our results are the first to propose mechanisms underlying autoantigen-specific tolerance in humans. We identify permissive central tolerance, defective peripheral tolerance and heterogenous autoantibody binding properties as sequential pathogenic steps which licence CASPR2-directed pathology. By leveraging the basic immunobiology, we rationally direct tolerance-restoring approaches in CASPR2-antibody diseases. This paradigm is applicable across autoimmune conditions.

Importance There is a lack of long-term efficacy and safety data on hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN) and on RNA interference (RNAi) therapeutics in general. This study presents the longest-term data to date on patisiran for hATTR-PN. Objective To present the long-term efficacy and safety of patisiran in adults with hATTR-PN. Design, Setting, and Participants This global open-label extension (OLE) of the APOLLO randomized clinical trial and phase 2 OLE study enrolled patients from 43 hospitals or clinical centers across 19 countries between July 2015 and August 2017, with follow-up until November 2022. Of 212 eligible patients with hATTR who completed the phase 3 APOLLO or phase 2 OLE parent studies, 211 enrolled in and 138 completed the global OLE. Intervention Patisiran, 0.3 mg/kg, intravenously once every 3 weeks for up to 5 years. Main Outcomes and Measures Outcomes evaluated at year 5 of the global OLE included disability (polyneuropathy disability [PND] score); polyneuropathy severity (Neuropathy Impairment Score [NIS]), nutritional status (modified body mass index [mBMI]), quality of life (Norfolk Quality of Life–Diabetic Neuropathy [Norfolk QOL-DN]), and Rasch-Built Overall Disability Scale (R-ODS), with no statistical hierarchy. Safety, survival probability, and mortality were also assessed. Results At the global OLE baseline, the mean (SD) age was 61.3 (12.3) years, and 156 patients (73.9%) were male. In 138 patients completing the study, PND scores remained stable or improved in 89 patients (65.0%), NISs showed a mean (SD) change of 10.9 (14.7), and mean (SD) mBMI (calculated as weight in kilograms divided by height in meters squared times serum albumin in grams per liter) increased by 46.4 (120.7) over 5 years from baseline. Norfolk QOL-DN and R-ODS scores showed mean (SD) changes of 4.1 (16.7) and –3.7 (6.2), respectively. Adverse events (AEs) leading to study withdrawal occurred in 47 patients (22.3%). Infusion-related reactions were the most common treatment-related AE (n = 34 [16.1%]). Overall, 41 patients (19.4%) died during the study. Patisiran treatment in the parent study and low familial amyloid polyneuropathy score at parent study baseline were associated with significantly improved survival. Conclusions and Relevance In the longest study of an RNAi therapeutic for any disease, patisiran treatment resulted in modest changes for patients with hATTR-PN with an acceptable safety profile. These results highlight the importance of initiating early treatment for hATTR and the potential of RNAi therapeutics in medicine. Trial Registration ClinicalTrials.gov Identifier: NCT02510261