Citations

Abstract Monoclonal antibodies targeting CD38 are a therapeutic mainstay in multiple myeloma (MM). Although they have contributed to improved outcomes, most patients still experience disease relapse, and little is known about tumor-intrinsic mechanisms of resistance to these drugs. Antigen escape has been implicated as a mechanism of tumor-cell evasion in immunotherapy. Yet, it is unknown whether MM cells can develop permanent resistance to anti-CD38 antibodies by acquiring genomic events leading to biallelic disruption of the CD38 gene locus. Here, we analyzed whole-genome and whole-exome sequencing data from patients 701 newly diagnosed MM, 67 patients at relapse with naivety to anti-CD38 antibodies, and 50 patients collected at relapse after anti-CD38 antibodies. We report a loss of CD38 in 10 of 50 patients (20%) after CD38 therapy, 3 of whom exhibited a loss of both copies. Two of these cases showed convergent evolution in which distinct subclones independently acquired similar advantageous variants. Functional studies on missense mutations involved in biallelic CD38 events revealed that 2 variants, L153H and C275Y, decreased binding affinity and antibody-dependent cellular cytotoxicity of the commercial antibodies daratumumab and isatuximab. However, a third mutation, R140G, conferred selective resistance to daratumumab, while retaining sensitivity to isatuximab. Clinically, patients with MM are often rechallenged with CD38 antibodies after disease progression and these data suggest that next-generation sequencing may play a role in subsequent treatment selection for a subset of patients.

Abstract Objective The successful diagnosis and classification of lymphoid neoplasms in blood and bone marrow is the responsibility of the practicing pathologist. This guide provides a general “roadmap” for this process, from initial case recognition to final classification. Methods The integration of hematologic, morphologic, immunophenotypic, and genetic features for the full spectrum of precursor and mature B-cell, T-cell, and natural killer–cell neoplasms that typically manifest in blood and bone marrow is included. Results Classification systems for lymphoid neoplasms provide criteria for pathologists to render a diagnosis that is optimal for patient care, treatment, and outcome prediction. Conclusions This guide provides diagnostic strategies for lymphoid neoplasms encountered in blood and bone marrow specimens using both the International Consensus Classification and the World Health Organization fifth edition classification systems. Key tips are provided for each entity along with testing requirements, differential diagnosis, nonneoplastic mimics, and other unique features based on the experience of the Bone Marrow Pathology Group members.

Hyperdiploid multiple myeloma (Hy‐MM) is a common (50% of MM cases), but frequently under‐recognized subtype of MM. Hy‐MM is characterized by the presence of multiple trisomies of the odd numbered chromosomes (with the exception of chromosomes 13 and 17), leading to an average chromosome count of 53. Despite its prevalence, Hy‐MM tends to receive less attention compared to high‐risk subtypes. Thus, gaps in our understanding of Hy‐MM remain underscoring the need for continued research ultimately to aid in targeted therapies and personalized treatment strategies to improve outcomes in this subgroup.

PURPOSE Continued improvement in outcomes is needed for advanced cutaneous squamous cell carcinoma (cSCC). Methods Alliance A091802 is a randomized phase II trial of avelumab (800 mg IV once every 2 weeks) plus cetuximab (500 mg/m 2 IV once every 2 weeks) versus avelumab alone once every 2 weeks for up to 2 years. Cetuximab was given for 1 year in the avelumab + cetuximab arm. Crossover at progression to avelumab + cetuximab was allowed. Randomization was 1:1, stratified by PD-L1 and HIV status. Patients had distant metastatic or unresectable locally advanced cSCC, were anti–PD-1/PD-L1 monoclonal antibody–naive, had no previous cetuximab in the advanced setting, had an Eastern Cooperative Oncology Group performance status of 0-2, and could be HIV+ (CD4 >200, viral load <200). Patients with chronic lymphocytic leukemia, immunosuppression, or active autoimmune diseases were excluded. The primary end point was progression-free survival (PFS; null hypothesis: median = 12 months v alternative hypothesis: 21 months or a 75% improvement, power of 80% with one-sided alpha .2, n = 57, 37 PFS events required). Secondary end points were overall survival, objective response rates (ORRs), clinical benefit rate, and toxicity. RESULTS Sixty patients were enrolled; 57 patients were evaluable. The median age was 72 years, all were HIV–; 75.4% was PD-L1+, 84.2% had head/neck origin, 47.4% had distant metastasis, and there were no differences in baseline characteristics by arm. Avelumab + cetuximab significantly improved PFS versus avelumab (median, 11.1 [7.6-not reached (NR)] v 3.0 months [2.7-13.6] hazard ratio, 0.48 [95% CI, 0.23 to 0.97], P = .018). Avelumab patients who crossed over (n = 9) to combination had a median PFS after crossover of 11.3 months (5.8-NR). The confirmed ORR was 27.6% with avelumab + cetuximab and 21.4% with avelumab. Grade 3 treatment-related adverse events occurred in 48.3% and 21.5% of patients with avelumab + cetuximab (most common: rash [20.7%], infusion reaction [20.7%]) and avelumab, respectively. CONCLUSION Avelumab + cetuximab significantly improved PFS versus avelumab alone in patients with advanced cSCC. Alliance A091802 supports a larger confirmatory study with the combination of cetuximab and PD-1:PD-(L)1 blockade.

ABSTRACTBackground/ObjectivesImmune‐mediated skin disorders, such as immunobullous dermatoses and leukocytoclastic vasculitis, rarely affect children. While direct immunofluorescence (DIF) biopsy is a standard diagnostic tool, limited data exist on pediatric DIF patterns, rates of positivity, pretest diagnostic concordance, and the relevance of biopsy site. This study sought to address these gaps.MethodsDIF data from all skin and mucosal specimens interpreted at Mayo Clinic's reference immunodermatology laboratory for patients aged 0–18 years (August 22, 2017 to November 30, 2023) were reviewed. DIF results were classified as positive if a characteristic pattern was seen and negative if the findings were negative or nondiagnostic.ResultsOf 986 pediatric DIF studies, 153 (15.5%) were positive and comparable to adult positivity rates (20.9%) during the same period. The most frequent DIF patterns were IgA‐predominant vasculitis (N = 85/153; 55.5%) and lichenoid tissue reaction (N = 21/153;13.7%). Concordance between pretest diagnosis and positive DIF results was highest for linear IgA bullous dermatosis (N = 7/7; 100%) and dermatitis herpetiformis (N = 6/6; 100%). Excluding these entities, DIF changed the pretest diagnosis in 16.7% (N = 19/114) of cases. While lower extremity biopsies were initially more likely to yield positive DIF results, this association disappeared when IgA vasculitis cases were excluded.ConclusionThe most frequent DIF pattern in children was that of IgA‐predominant vasculitis. Pediatric DIF positivity rates closely mirrored those of adults, supporting similar biopsy thresholds. DIF results differed from the pretest impression in a substantial percentage, supporting the value of DIF in select situations in the pediatric population. After controlling for IgA vasculitis, biopsy site was not associated with DIF positivity.

10035 Background: Ewing sarcoma (EwS) is a rare malignancy of children, adolescents and young adults for which outcomes have progressively improved through intensification of conventional chemotherapy, including interval compression of cycles. Prior cooperative group reports of relapsed EwS included patients treated less intensively and with fewer treatment options at relapse. Here, we report overall survival (OS) and prognostic factors post-first recurrence in patients with EwS treated with frontline interval-compressed chemotherapy. Methods: We included patients treated on the last three phase 3 COG EwS studies treated with interval compressed chemotherapy, which accrued from 2001-2019. Patients with initially localized disease (L-EwS) were treated on AEWS0031 arm B and AEWS1031. Patients with initially metastatic disease (M-EwS) were treated on AEWS1221. The primary outcome was OS from first relapse. Demographic and clinical data from original diagnosis and from relapse were analyzed as potential prognostic factors. Kaplan-Meier survival curves were constructed and groups compared with log-rank tests. Results: 366 patients experienced disease recurrence as first event and were included in this analysis (AEWS0031 arm B, n = 69, AEWS1031, n = 115, for a total of 184 with L-EwS; AEWS1221, n = 182, all with M-EwS). Median age at relapse was 16 years. Median time from initial enrollment to first relapse was 1.52 years and was shorter for patients with M-EwS (Kruskall-Wallis, p < 0.001). First relapses were isolated local, isolated distant, and combined in 24%, 70%, and 6.4% of patients, respectively. Metastatic stage at initial diagnosis was associated with increased risk of post-first recurrence OS event (p < 0.0001). Two-year OS post-first recurrence (OS 2y ) was 25.6% for patients with M-EwS and 48.5% for patients with L-EwS. Time to first recurrence was also a predictor of post-recurrence survival (p < 0.0001): patients with initial L-EwS and relapse < 2 years from diagnosis had OS 2y of 31.4% vs. 70.8% for later relapses. Patients with initial M-EwS and relapse < 2 years from diagnosis had OS 2y of 18.9% vs. 71.2%. Patients with combined relapses had higher risk of post-relapse death compared to other patterns of failure (p = 0.003), an effect that was largely driven by the one seen in patients with initial L-EwS. Conclusions: Overall survival of patients with first recurrent EwS after having received modern era therapy with interval compressed chemotherapy on recent COG trials remains poor, particularly for M-EwS, early relapse and combined relapses. These data will inform the design of trials for this relapsed population and provide critical data to help counsel patients about goals of care at first relapse.

6002 Background: There is a need for continued improvement in outcomes with systemic therapy for advanced cSCC. Pre-clinical data suggest immunologic synergy between IgG1 mAb therapy targeting EGFR and PD-1:PD-(L)1 blockade. Methods: Alliance A091802 is a randomized phase II trial of avelumab (AV) (800 mg) plus cetuximab (C) (500 mg/m2) vs. AV alone every 2 weeks for up to 2 years (yrs). C was given for 1 yr in the AV+C arm. Crossover at progression to AV+C was allowed in the AV arm. Randomization was 1:1 and stratified by PD-L1 [+(>1%) vs. -] and HIV status (+ vs. -). Eligible patients (pts) had distant metastatic or unresectable locally advanced cSCC, anti-PD-1/PD-L1 mAb naive, no prior cetuximab in the advanced setting, ECOG PS 0-2, HIV+ if CD4 >200 and VL <200. Pts with CLL, immunosuppression, or active autoimmune diseases were excluded. The primary endpoint was progression-free survival (PFS) (Ho: Median=12 mo vs Ha: 21 mo or a 75% improvement, power of 80% with one-sided alpha 0.2, n=57, 37 PFS events required). Secondary endpoints were overall survival (OS), confirmed response rate (ORR), clinical benefit rate, and toxicity. After 31/37 events, an early unplanned analysis (along with sensitivity analyses) was performed because it became apparent that 37 events would not be reached. These results were submitted to the Alliance Data and Safety Monitoring Board, which recommended releasing the data. Data cutoff was 1/16/25. Results: 60 pts were enrolled between 2019-2023; 57 pts were evaluable. Median age was 72 yrs (41‒93), 96.5% were white, 91.2% male, all HIV-; 75.4% PD-L1+. 84.2% were head/neck origin, 47.1% had distant metastasis, and there were no differences in baseline characteristics by arm. AV+C significantly improved PFS compared to AV [median 11.1 months (mo) (7.6‒not reached (NR)) vs. 4.8 mo (2.8‒NR) hazard ratio (HR) 0.53 95% CI (0.26‒1.09), one-sided p=0.041]. The median OS of AV+C vs. AV was NR (25.2‒NR) vs. 35.8 mo (18.6‒NR) HR 0.77 (0.33‒1.78) p=0.267. ORR was 31.0% in the AV+C arm and 21.4% in the AV arm. Treatment-related adverse events (TRAE) of any grade (G) occurred in 93% and 78.6%, respectively, and were G>3 in 48.3% and 21.5% of pts in the AV+C [most common G3 TRAEs were rash (20.7%) and infusion-related reaction (20.7%)] and AV arms, respectively. There were no G5 events. Outcomes after crossover and by PD-L1 status will be presented subsequently. Conclusions: Avelumab plus cetuximab significantly improved PFS vs. avelumab alone in advanced cSCC pts, without unexpected toxicity. Alliance A091802 supports a larger confirmatory study with combination cetuximab and PD-1:PD-(L)1 blockade. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180868 (NRG Oncology); U10CA180888 (SWOG); https://acknowledgments.alliancefound.org . EMD Serono CrossRef Funder ID: 10.13039/100004755. Clinical trial information: NCT03944941 .

1586 Background: Black and Hispanic breast cancer (BC) survivors have a higher prevalence of obesity and experience less success with weight loss interventions (WLI) than White BC survivors. The BWEL trial (Alliance A011401; NCT02750826) is a phase III randomized trial evaluating the impact of a 2-year telephone-based WLI on invasive disease-free survival in participants (pts) with stage II-III HER2-negative BC and a BMI ≥ 27 kg/m 2 . At 12-months, the WLI induced significant weight loss across demographic factors, including race and ethnicity. However, Black and Hispanic pts lost less weight and completed fewer calls than White pts. Here, we evaluate intervention adherence, engagement and tool utilization in BWEL pts by race and ethnicity. Methods: BWEL randomized pts to a WLI plus health education (HE) or HE alone. WLI pts received semi-structured telephone-based health coaching, delivered in English or Spanish, and received an activity monitor and wireless scale. Pts self-reported race and ethnicity. Mean values for call duration, call density (time to complete the initial 12-week intensive intervention phase), intervention attrition, and frequency of Fitbit use and weight tracking over 12-months were compared by race and ethnicity, comparing least squares means with Tukey-Kramer adjustment for multiple comparisons with adjusted p-values. Results: Of 3181 pts randomized to the study between 08/2016 and 02/2021, 1591 pts were allocated to the WLI arm. 80.5% of pts were White, 12.8% Black, and 7.1% Hispanic. Average BMI was 34.5 (±5.7) kg/m2. Compared to White pts, Black pts had fewer days of Fitbit usage (113.6 vs. 159.8, p<0.0001) and weight tracking (77.9 vs. 135.6 days, p< 0.0001). Hispanic pts had fewer days of Fitbit usage (108.8 vs. 154.9, p= 0.001) and weight tracking (87 vs. 129.5 days, p=0.0002) compared to non-Hispanic pts. There were no differences in attrition rate, average call duration, or call density by race or ethnicity. Conclusions: In a phase III WLI trial, engagement with tools designed to support weight loss was significantly lower in Black and Hispanic pts. Future work is needed to explore ways to enhance engagement and improve weight loss outcomes for racial and ethnic minority pts. Support: U10CA180821, U10CA180882, UG1CA189823; https://acknowledgments.alliancefound.org . Clinical trial information: NCT02750826 . Measure of engagement Race Ethnicity WhiteN=1281 BlackN=204 p-value Non-HispanicN=1459 HispanicN=113 p-value Withdrew from intervention n (%) 58 (4.5%) 13 (6.4%) 0.56 70 (4.8%) 6 (5.3%) 0.51 Call Duration (min)Mean (SD) 34.5 (7.6) 34.6 (9.1) 0.99 34.6 (7.8) 33.3 (7.9) 0.25 Call density(weeks)Mean (SD) 14.2 (7.2) 14.2 (8.8) 0.99 14.2 (7.3) 14.2 (9.7) 0.99 Days of Fitbit UseMean (SD) 159.8 (132.2) 113.6 (124.7) < 0.0001 154.9 (131.8) 108.8 (125.7) 0.001 Days of weight trackingMean (SD) 135.6 (109.5) 77.9 (87.5) < 0.0001 129.5 (108.8) 87 (96.5) 0.0002

e13575 Background: Cellular therapies continue to expand in diversity, complexity, and financial impact leading clinicians and administrators to seek innovative care options. The paradigm of late has been to move to an outpatient treatment model. However, centers may not find this model to be the safest option for their patients. This pilot project aims to use established outpatient resources to reduce hospital length of stay (LOS) for patients receiving ciltacabtagene autoleucel in an inpatient setting. Methods: Chart review was conducted for 42 patients treated for incidence of CRS, days to onset, LOS, readmissions, and hospital expenses and charges. The cohort showed an 83% incidence of CRS with a mean onset of 7 days. 71% of CRS was limited to Grade 1. The mean LOS was 10.8 days and the readmission rate was 21%. Financial modeling estimated overall cost reduction to range from $13,000 to $20,000 per patient for a LOS of 3 days. A pilot project to reduce LOS was developed with inclusion/exclusion criteria prioritizing patient safety and likelihood of remaining in the outpatient setting. A workflow for administering one dose of tocilizumab for Grade 1 CRS in the outpatient setting was also established to counterbalance readmissions. The goal of the pilot is to reduce the overall LOS from 10 days to 3 days while maintaining readmission rates and comparable charge to reimbursement ratios on net operating income. Results: In the first five months, 25 patients were screened for eligibility. 60% were deemed eligible and 66% of those were discharged after three days. No patients discharged after a minimum admission were readmitted within three days. Current data suggests the readmission rate within 30 days is higher than baseline at 40%. The overall LOS of patients enrolled in the pilot upon infusion was six days. Patients successfully remaining on the pilot have a 60% reduction in LOS. There have been no major safety events. Conclusions: We identified that select patients could be managed in the outpatient setting after a minimum three-midnight hospital admission. A pilot project was developed using our comprehensive care model coupled with a minimum LOS of 3 days. After discharge, patients are followed daily in our outpatient clinic using in-person visits and remote patient monitoring. To counterbalance readmissions, Grade 1 CRS has been treated in the outpatient clinic including administration of tocilizumab. Early data indicates that the workflow is reducing LOS by 60% under patient selection criteria capturing approximately 60% of patients. While readmissions in the first three days post discharge have been parried, there is opportunity to further reduce readmissions in the first 30 days following CAR-T infusion. We anticipate the pilot will reduce costs without negatively impacting reimbursement or readmissions.