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ABSTRACT Prior surveys of chronic automated red blood cell exchange (RCE) for patients with sickle cell disease (SCD) have identified considerable procedural variability, especially with the use of isovolemic hemodilution red blood cell exchange (IHD‐RCE). We conducted a survey of chronic RCE practices among American Society for Apheresis (ASFA) members to identify opportunities for practice harmonization and future studies. The ASFA SCD Research Subcommittee developed a 72‐item survey of chronic RCE practices, with a focus on IHD‐RCE. The survey was validated internally and distributed by email to all ASFA members from September 2024 to February 2025. One survey response from each institution was retained for data analysis. Descriptive statistics were performed. Sixty‐two survey responses, including three from international institutions, were retained for analysis. Sixty‐one percent of respondents (38/62) reported using at least one fixed RCE target, with end hematocrit being the most common fixed parameter (40%, 25/62), followed by fraction of cells remaining (31%, 19/62) and hemoglobin S% (27%, 17/62). Most respondents (60%, 37/61) performed IHD‐RCE at their institution, though other details such as the minimum hematocrit, exclusion criteria, and response to adverse effects were variable. Consistent pre‐ and post‐RCE laboratory monitoring practices were reported. Consistent with earlier surveys, procedural variability in chronic RCE practices for patients with SCD is observed. This highlights opportunities to compare outcomes where practice variability exists. Consensus guidelines based on institutional practices with optimal outcomes should be developed.

Radioactive seed localization (RSL) using 125 I is widely employed for the surgical resection of nonpalpable breast lesions due to its precision and scheduling flexibility. Although clinical experience supports its safety, quantifying radiation dose to surrounding healthy breast tissue remains important for establishing conservative operational guidelines, including acceptable implant duration prior to surgery. In this study, cumulative dose to healthy breast tissue from an implanted 125 I localization seed was evaluated using two independent computational approaches: a simplified hemispherical breast model implemented in MATLAB and a Monte Carlo simulation developed in Mathematica. Both models incorporated dosimetric parameters from AAPM Task Group 43, including the dose-rate constant, radial dose function, and two-dimensional anisotropy function, along with tissue properties consistent with International Commission on Radiological Protection recommendations. Results from both models demonstrated that cumulative dose decreases rapidly with increasing distance from the seed and increases slowly with implantation time due to the low dose rate and long half-life of 125 I. At a distance of 1 cm, cumulative dose reached approximately 3–4 cGy after 5 d and approximately 50 cGy only after extended implantation times exceeding 200 d. Agreement between the MATLAB and Monte Carlo models was within expected limits given differences in deterministic and stochastic modeling approaches. These findings indicate that radiation dose to healthy breast tissue from RSL remains well below thresholds associated with deterministic effects for clinically relevant implantation times. The results support the use of a conservative “no later than” removal date while reaffirming the radiological safety and practical advantages of 125 I seed localization in breast cancer surgery.

TPS2673 Background: The main challenge for developing CAR T therapies for solid tumors is the lack of targets that distinguish tumor from normal cells, resulting in on-target, off-tumor toxicity. Tmod logic-gated CAR T therapy addresses this challenge by incorporating 2 CARs on the same T cell: an activator targeting a marker on both tumor and normal cells, and a blocker targeting HLA-A*02 that inhibits CAR T activity against normal cells while allowing activation against tumor cells (with HLA-A*02 LOH), improving tumor selectivity and decreasing toxicity. Early safety results from 3 ongoing phase 1/2 clinical trials of logic-gated, Tmod CAR T therapy (EVEREST-1, EVEREST-2, and DENALI-1) have demonstrated manageable safety and tolerability in patients with advanced solid tumors (Grierson et al, SITC , 2024; Ward et al, SITC 2025; Specht et al, SABCS , 2025). Early efficacy results include the first ever reported complete response in a patient with non-small cell lung cancer following treatment with a CAR T-cell therapy (A2B694). A2B543 is an autologous Tmod CAR T therapy that contains the same Tmod construct as A2B694 with an added membrane-tethered IL-12 (memIL12) booster. Specifically, A2B543 is comprised of autologous Tmod cells transduced with 2 lentiviral vectors: one expressing both the HLA-A*02-targeted blocker and the mesothelin-targeted CAR activator; and a second expressing the memIL12 booster. Interleukin 12 (IL-12) is a potent, pro-inflammatory cytokine that plays a crucial role in inducing antitumor immune responses; however, systemic IL-12 can be prohibitively toxic (Jia et al, Front Immunol , 2022). In A2B543, expression of the memIL12 cassette is under the control of an NFAT promoter and is induced during antigen engagement or T cell activation. This inducible memIL12 is designed to reduce the toxicity associated with systemic IL-12 while enhancing the long-term potency and persistence of Tmod (Zhang et al, J Immunother Cancer , 2025). Methods: EVEREST-2 (NCT06051695) is a phase 1/2, open-label, nonrandomized study evaluating the safety and efficacy of A2B543 in adults with recurrent/metastatic mesothelin-expressing cancers with tumor-associated HLA-A*02 LOH, including mesothelioma, colorectal, non-small cell lung, pancreatic, or ovarian cancer. Patients are enrolled through BASECAMP-1 (NCT04981119), a master prescreening study that identifies patients with HLA LOH via next-generation sequencing and cryopreserves leukapheresis product. Upon progression, A2B543 is manufactured and then administered after lymphodepletion. The phase 1 primary objective is to evaluate the safety and tolerability of A2B543 and identify a recommended phase 2 dose (RP2D). The phase 2 primary objective is to assess overall response rate. Clinical trial information: NCT06051695 .

9510 Background: Although acute toxicities associated with adoptive cellular therapy using lifileucel are well described and largely occur within the first 2 weeks of treatment, adverse events beyond this early window remain incompletely characterized. We sought to characterize treatment-related adverse events (AEs) with emphasis on those starting or persisting ≥2 weeks after lifileucel infusion. Methods: We conducted a retrospective multicenter study across three centers (Moffitt Cancer Center, Massachusetts General Hospital, and Mayo Clinic). Patients with advanced melanoma treated with lifileucel were included. The primary endpoint was incidence and characterization of AEs occurring or persisting ≥2 weeks after standard of care lifileucel infusion. Results: Among 79 patients (median follow-up 11 months [95% CI, 9.6–15]), median age was 63 years (range 30–79), 59% were male (n = 47), 41% were female (n = 32), and ECOG PS was 0–1 in 98%. Patients received a median of 5 IL-2 doses (range 0–6). Of 79 patients, 78 experienced treatment-related adverse events that either persisted or occurred >2 weeks after cell infusion. A total of 308 delayed treatment-related adverse events were identified; 96 were new events (31%) and 212 (69%) were continued toxicities that started < 2 weeks after cell infusion. Lymphopenia was the most common delayed or persistent toxicity, occurring in a majority of patients (n = 68/79, 86%). Treatment-associated anemia (n = 59/79, 75%), fatigue (n = 56/79, 71%) and thrombocytopenia (n = 24/79, 30%) were also common. Viral infections occurred in 9.0% (n = 7), including CMV/EBV viremia (n = 1) and respiratory or gastrointestinal viral infections (metapneumovirus, parainfluenza, SARS-CoV-2, and norovirus). Hemophagocytic lymphohistiocytosis (HLH) occurred in 2 patients (n = 2/79, 3%) and was fatal in both cases. No other toxicity related deaths were noted. Autoimmune toxicities directly attributable to TIL included vitiligo in 9% (n = 7; median onset 41 days), uveitis in 5% (n = 4; median onset 26 days), and sensorineural hearing loss in 1% (n = 1; onset 28 days). All patients underwent TIL infusion in the inpatient setting; a total of 14 of 79 patients (18%) were re-admitted after discharge due to treatment-related toxicity (median time from infusion 19 days). Conclusions: In this multicenter real-world cohort, toxicities persisting beyond two weeks were largely driven by lymphodepleting chemotherapy–associated immunosuppression and cytopenias. These findings highlight the importance of structured post-discharge monitoring and support ongoing efforts to de-intensify lymphodepleting chemotherapy to improve safety while maintaining clinical benefit.

9551 Background: Lymphodepleting (LD) chemotherapy is required prior to tumor-infiltrating lymphocyte (TIL) therapy, yet the depth, kinetics, and completeness of peripheral T-cell recovery in practice remain poorly defined. Using a pooled, multi-institution cohort, we characterized longitudinal CD4 and CD8 T-cell reconstitution and the prevalence of CD4 lymphopenia following TIL therapy. Methods: We conducted a retrospective multicenter study across Mayo Clinic, Moffitt Cancer Center, and Massachusetts General Hospital of patients with metastatic melanoma treated with TIL (N = 41, median follow-up 7.6 months). Absolute CD4 and CD8 T-cell counts and CD4:CD8 ratios were assessed at baseline (pre-LD), week 4, month 3, and month 6 post-TIL. Clinically significant CD4 lymphopenia was defined as CD4 < 200 cells/µL. All patients received Pneumocystis jirovecii and antiviral prophylaxis, with antibacterial and antifungal prophylaxis administered per institutional protocols. Post-TIL infections were recorded. Paired changes from baseline were evaluated using Wilcoxon signed-rank testing. Results: Median age was 65 years (range 35-79), and 68% were male. At baseline, 16 patients (39%) had CD4 counts below the institutional lower limit of normal prior to LD. Eighteen patients (44%) received bridging therapy prior to TIL and had lower baseline CD4 and CD8 counts compared with those who did not ( p < 0.05 for both); however, post-TIL CD4 and CD8 recovery trajectories did not differ between groups. CD4 counts declined sharply following LD and demonstrated incomplete and heterogeneous recovery. Median CD4 decreased from 490 cells/µL at baseline to 250 at week 4, 290 at month 3, and 220 at month 6, remaining significantly below baseline at all post-TIL timepoints ( p < 0.05). Clinically significant CD4 lymphopenia was observed in 45% (10/22) of evaluable patients at month 3 and in 50% (44%, 7/16) at month 6. In contrast, CD8 counts increased early after TIL (median 240 to 590 cells/µL at week 4; p = 0.004) and remained higher than baseline at month 6. The CD4:CD8 ratio inverted from a median of 2.02 at baseline to 0.46 at week 4 and remained below 1.0 through month 6, reflecting sustained CD4 suppression despite CD8 recovery. Post-TIL infections occurred despite widespread prophylaxis, including bacterial (13%), viral (10%), and fungal (4.9%) infections. Conclusions: In a multi-institution cohort, LD chemotherapy preceding TIL is associated with profound and prolonged CD4 T-cell suppression, persistent CD4:CD8 inversion, and a high prevalence of CD4 < 200 cells/µL through 6 months. These findings identify delayed immune reconstitution as a common and clinically relevant consequence of TIL therapy and support prospective optimization of antimicrobial prophylaxis duration, vaccination timing, and immune monitoring strategies.

8579 Background: LOH may provide a means to target tumor versus normal cells, to augment the efficacy and safety of MSLN-targeted programs (Hecht et al. JCO . 2022). A2B694 is an autologous, logic-gated, Tmod CAR T therapy designed to improve tumor selectivity and decrease toxicity by integrating an MSLN CAR activator with an HLA-A*02 blocker (Hamburger et al. Mol Imm. 2020). Methods: The first-in-human, open-label, phase 1/2 EVEREST-2 (NCT06051695) study of A2B694 in patients with recurrent/metastatic MSLN-expressing cancers with tumor-associated HLA-A*02 LOH. The prescreening study BASECAMP-1 (NCT04981119) identifies eligible patients and cryopreserves leukapheresis product. Upon progression, A2B694 is manufactured and administered after lymphodepletion. Phase 1 primary objective: evaluate the safety and tolerability of A2B694 and identify a recommended phase 2 dose. Results: As of 05 January 2026, 13 patients were enrolled: 8 women/5 men, median age 59 years, 11 non-Hispanic White/2 Hispanic with unknown race. Tumor types included colorectal (n = 4), ovarian (n = 3), pancreatic (n = 3), non–small cell lung adenocarcinoma (NSCLC), gastro-esophageal, and mesothelioma (n = 1 each). A2B694 dose level (DL) groups were: DL1: 1×10 8 cells (n = 3), DL2: 2×10 8 cells (n = 4), DL3: 4×10 8 cells (n = 5), and DL4: 6×10 8 cells plus low-dose IL-2 (n = 1). Lymphodepletion prior to administration of A2B694 was well-tolerated, with expected, transient cytopenias. The only adverse event reported in more than 1 patient was grade 3 neutropenia. One patient had grade 3 ICANS and 1 patient had grade 1 CRS. There were no dose-limiting toxicities or new safety signals after up to 17 months follow-up. All 13 patients received A2B694, were efficacy-evaluable, and had A2B694 detected post-infusion in peripheral blood. While A2B694 was not detected in tumor biopsies collected in patients treated at DL1 (0/2), all patients treated at DL2-DL4 with available biopsies (3/3) had detectable A2B694 in the tumor microenvironment. A patient with KRAS G12V /STK11 co-mutated NSCLC who had progressed on carboplatin, pemetrexed, and pembrolizumab achieved a complete response (CR) at D90 post-infusion per RECIST 1.1 by central review and had a confirmed CR at D180. In addition, PET-CT scan and ctDNA on D190 demonstrated no evidence of disease. On D243, the patient had a CNS relapse, with an ongoing non-CNS CR per RANO-BM at D284. At M12, the patient's CT showed no new findings and persistence of A2B694 in the blood was confirmed by ddPCR. Conclusions: We report the first patient with NSCLC to have a CR after CAR T. Overall, A2B694 demonstrated manageable safety and tolerability in patients with advanced solid MSLN-expressing tumors with tumor-associated HLA-A*02 LOH. The maximum tolerated dose has not been reached; dose-escalation continues. Clinical trial information: NCT06051695 .

4559 Background: Baseline QOL has been linked to survival in mRCC therapy clinical trials (Cella, 2024); however, there is a paucity of prospectively collected real-world QOL data across front-line management strategies. We used data from ODYSSEY to examine the relationship between baseline QOL and early death. Methods: ODYSSEY is a multi-site, prospective observational study of 468 US pts with mRCC. Pts must have mRCC (any histology); have no prior systemic therapy (ST) or be within 3 months of starting ST; and follow up at a PCORnet study site. Exclusion criteria include treatment for cancer except mRCC. The primary objective is to determine patterns of change in QOL and symptom burden of pts with mRCC. Early death was defined as death within 12 months post-enrollment. All pts with non-missing FKSI-19 or FKSI-DRS at enrollment were included. Cumulative event probabilities as a function of time were stratified by either < or ≥ median QoL value and plotted as a step function vs time since enrollment to create cumulative event curves. To determine association between QoL at enrollment and early death, separate Cox proportional hazards models (unadjusted and adjusted) for time-to-first-event as a function of baseline QoL were fit. The adjusted model controlled for the following baseline covariates: IMDC risk (favorable vs intermediate or poor), histology (clear cell vs non). Results: As of 1/5/26, 468 pts were enrolled; 425 had non-missing FKSI-19 or FKSI-DRS at enrollment (329 immediate ST, 96 deferred ST [DST]). ST included 129 IO-IO, 108 IO-TKI, 92 Other. DST included 57 Active Surveillance, 22 Local Therapy Planned, 17 Other/Missing. 209 and 190 pts have < median FKSI-19 (score = 59) and FKSI-DRS (score = 29), respectively; 216 and 235 pts have ≥ median FKSI-19 and FKSI-DRS, respectively. Those below the median have lower rates of nephrectomy, worse IMDC risk and KPS, shorter time since RCC diagnosis, and higher rates of bone metastasis (all p<0.05). Cumulative event probabilities for death at 12 months are 21% and 7% in those < and ≥ median baseline FKSI-19, respectively; and 21% and 7% in those < and ≥ median baseline FKSI-DRS, respectively. For FKSI-19, the unadjusted hazard ratio (HR) for early death is 0.55 (95% CI: 0.43 – 0.70; p<0.001) and adjusted HR is 0.65 (0.49 – 0.85; p = 0.002) per 1 SD higher score. For FKSI-DRS, the unadjusted HR for early death is 0.57 (95% CI: 0.46 – 0.71; p<0.001) and adjusted HR is 0.66 (0.51 – 0.86; p =0.002) per 1 SD higher score (higher score indicates better QOL). Conclusions: Across management strategies in our ODYSSEY cohort of systemic therapy naïve mRCC patients, better baseline QOL was associated with better survival. This is to our knowledge the largest reported real world mRCC cohort with prospectively collected PROs. Future analyses will focus on association of outcomes with longitudinal PROs. Clinical trial information: NCT04919122 .

Abstract INTRODUCTION To examine the generalizability of Alzheimer's disease (AD) biomarker models in real‐world older adults, we examined AD biomarker relationships with cognition in two multicenter cohorts that differ with respect to recruitment approach and health risk factors but were matched on a variety of characteristics. METHODS We compared harmonized health and demographic data, AD and cerebrovascular biomarkers, and cognitive performance in the community‐recruited U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) Imaging substudy and a matched sample from the Alzheimer's Disease Neuroimaging Initiative (ADNI) which recruited primarily from academic specialty clinics. RESULTS Elevated β‐amyloid (Aβ) and tau were associated with cognitive performance in ADNI but not U.S. POINTER. Findings were consistent across different cohort matching schemes, and were not explained by discrepancies in vascular risk. DISCUSSION The role of Aβ and tau in cognitive performance may be reduced in real world samples compared to academic specialty clinics.

Introduction Individuals with inborn errors of immunity (IEI) are increasingly reaching reproductive age, yet guidance on fertility preservation, genetic counseling, medication adjustments in pregnancy and breastfeeding, monitoring for complications, and multidisciplinary coordination is lacking. This joint effort between two committees of the Clinical Immunology Society (CIS), the Women of the Clinical Immunology Society (WCIS) and the Adult Immune Deficiency Committee (AID) survey aimed to characterize current reproductive care practices for IEI patients. Methods A survey was disseminated to 809 CIS members. The response rate was 6.43% (52 respondents). The 24-item questionnaire addressed management of pregnancy in IEI, medications adjustment, participation in hematopoietic stem cell transplant (HSCT) care and fertility preservation, and maternal/neonatal outcomes. Results Because survey items were optional, the number of respondents varies by question. Forty-two participants completed core items: 64% (27/42) allergists/immunologists, 71% (30/42) practicing at academic centers, and 48% (20/42) with &gt;50% immunology-focused practices. Most respondents (78%, 41/52) currently or previously cared for pregnant/planning IEI patients. Preconception counseling was common (90%, 37/41), yet only 2% (1/41) have access to a formal reproductive multidisciplinary team. Among clinicians involved in HSCT care, 45% (13/29) referred patients for fertility preservation. More than half, 52% (22/42), observed reduced fertility in IEI patients, and 56% (20/36) observed adverse maternal outcomes. Medication management varied: 61% (24/39) discontinued known teratogenic medications, and 64% (25/39) adjusted dosing during pregnancy. Regarding immunoglobulin replacement therapy, 79% adjusted dosing based on IgG levels and 42% increased dosing by trimester. Conclusions This CIS survey reveals practice variability and notable gaps in reproductive health support for individuals with IEIs. Due to the relatively low response rate, generalizability across providers and practice settings is challenging. However, the results of this survey suggest that although most clinicians provide preconception counseling and manage IgG and immunomodulatory therapy during pregnancy, formal multidisciplinary structures are rare. High rates of reported fertility concerns and maternal complications underscore the need for enhanced collaboration with obstetrics/gynecology and the development of structured, evidence-based, multidisciplinary guidelines for reproductive care in IEI. Tabular data are included as downloadable supplement files.

Hip arthroscopy is an increasingly common procedure to treat intra‐articular conditions such as labral tears and femoroacetabular impingement. With the increase in frequency of such procedures, so too are revision arthroscopic hip procedures. Capsular repair in the setting of revision hip arthroscopy can be challenging due to the presence of adhesions and scar tissue formation that obscure tissue planes, suboptimal quality of residual capsular tissue, and the presence of capsular tissue defects. This technical note aims to describe the key surgical principles and considerations of revision hip capsular closure.