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e19531 Background: Effective treatment and elimination of clonal plasma cells (PC) in multiple myeloma (MM) are typically associated with recovery of polyclonal (normal) plasma cells (PPC). Studies suggest that robust PPC recovery is associated with better outcomes. However, it is unclear if this remains valid in the context of monoclonal antibodies, such as Daratumumab, that selectively target plasma cells, and in turn, may adversely impact PPC recovery. Methods: We identified patients with MM who underwent MRD testing using Euroflow method at 6-12 months after treatment initiation. Eight patients had disease progression prior to MRD testing and were excluded from further analysis. PPC was quantitated by the proportion of total events acquired during flow examination. Patients were considered MRD-negative if they had <1 clonal PCs in 10 5 cells, as detected in the marrow. We first examined the impact of initial therapy (Daratumumab vs. non-Daratumumab based regimens) and MRD status on PPC recovery. Subsequently, we analyzed impact of PPC recovery on patient outcomes in terms of progression-free survival (PFS) and overall survival (OS). Results: We identified 572 patients who had MRD testing by flow at a median of 9 months (range 6-12) after treatment initiation. The median age was 63 years, 58% were male. Daratumumab was part of initial therapy in 17% of patients; the most common induction therapies were PI-IMiD triplets (73%), and dara-PI-IMiD quads (15%). In our cohort, 74% of patients were MRD-negative. In our practice, only samples with no monotypic PCs identified on initial low-sensitivity flow proceed to MRD testing, hence, the proportion of MRD-negative patients appears higher in our study than previously reported. Median PPC was 0.02% and was similar between MRD-negative and -positive patients. We found the median PPC was significantly low in patients who received Daratumumab compared to the non-Daratumumab treated cohort (0.011% vs. 0.023%; p<0.01). There was a trend towards lower PFS and OS among the lowest PPC quartile group compared to the upper 3 quartiles, although this was not significant (p=0.07 for PFS and OS, Wilcoxon). This trend was more evident among patients who did not receive Daratumumab. Conclusions: Our study demonstrates negative impact of anti-CD38 therapy with Daratumumab on recovery of PPCs after initial treatment, consistent with the persistent hypogammaglobulinemia seen in clinical practice among these patients. However, unlike the observation with the non-Daratumumab treated cohort, the low proportion of PPCs does not significantly impact patient outcomes among patients who received Daratumumab.

e19545 Background: Cytogenetic abnormalities (CA) at diagnosis are important prognostic factors in multiple myeloma (MM), but there is limited information on how these abnormalities evolve at first relapse and their significance. Methods: This retrospective study included patients aged ≥18 years, with a confirmed diagnosis of MM who experienced at least one disease relapse and had fluorescence in situ hybridization analysis within six months of both diagnosis and relapse. Data on CA and clinical outcomes were collected. High-risk (HR) secondary CA were defined as the presence of deletion of chromosome 17p (del17p) or gain or amplification of chromosome 1q. The primary objective was to evaluate changes in HR secondary CA at first relapse, while the secondary objective was to assess the impact of the cytogenetic changes on overall survival (OS) from diagnosis. Based on the presence or absence of HR secondary CA, patients who were tested for HR secondary CA at both time points were classified into four groups: 1) persistent absence of HR secondary CA, 2) emergence of HR secondary CA at relapse, 3) persistent presence of HR secondary CA, and 4) loss of HR secondary CA at relapse. Results: A total of 233 patients diagnosed between 2004 and 2023 were included. HR secondary CA were tested in 98.7% (n= 230) of patients at diagnosis, with 24.8% (n=57) testing positive. At first relapse, testing for HR secondary CA was performed in 97.4% (n=227) of patients, of whom 23.8% (n=54) tested positive. Del17p was evaluated in 98.3% (n=229) of patients at baseline and 95.7% (n=223) at relapse, with positivity increasing from 10.9% (n=25) to 15.3% (n=34). Gain or amplification of chromosome 1q was evaluated in 49.4% (n=115) at baseline and 25.5% (n=60) at relapse, with positivity rate rising from 28.7% (n=33) to 38.3% (n=23). There were no differences in overall response rate or very-good-partial-response-or-better rates to the initial therapy at diagnosis between the groups. (Table) Emergence/persistence of HR CA were associated with lower OS from diagnosis. Conclusions: Emergence of HR secondary CA at first relapse in MM has prognostic significance. These findings highlight the importance of serial cytogenetic testing for risk stratification. Response rate to initial line of therapy and overall survival from diagnosis among patients tested for HR secondary CA both at diagnosis and first relapse (n=224). Outcome Persistent absence of HR secondary CA(n=142) Emergence of HR secondary CA at relapse (n=25) Persistent presence of HR secondary CA (n=27) Loss of HR secondary CA at relapse(n=30) p-value Overall response rate a 75% (106) 76% (19) 63% (17) 67% (20) 0.5 b Very-good-partial response or better response rate 43% (61) 36% (9) 44% (12) 40% (12) >0.9 b Median (95% CI) OS from diagnosis in years 11.3 (9.7-13.4) 7.5 (5.1-12.1) 6.1 (4.2-9.4) 10.1 (6.5-14.1) <0.0001 c a Partial response or better; b Chi-square test; c Log-rank test.

e19503 Background: The uptake of BCMA directed ADCs in MM has been hindered by ocular toxicity. Belantamab mafodotin (BM) and MEDI2228 (MEDI) are BCMA directed monoclonal antibodies conjugated to the microtubule inhibitor, monomethyl auristatin F and the alkylator, pyrrolobenzodiazepine, respectively. Differences in the ADCs payload, antibody specificity and linker stability influence ocular toxicity. We investigated the patterns of ocular toxicity and tolerability of BCMA directed ADC therapy. Methods: Retrospective study of MM patients who commenced treatment with a commercial or investigational BCMA directed ADC at the Mayo Clinic between 2019-22. Results: 111 patients were included, the median age was 69 and median follow up 40 months. The median number of prior treatments was 6, 87% of patients were triple class refractory, 50% penta class refractory, 14% had prior BCMA directed therapy and 24% had extraosseous disease. Treatments included BM (n=56, 50%), BM in combination with other MM therapy (n=12, 11%) and MEDI (n=43, 39%). The overall response rate was 30% for BM and 44% for MEDI. The median OS and PFS for BM was 8 and 2 months, the median OS and PFS for MEDI was 11 and 5 months. The median number of ADC cycles was 2.5. Ocular toxicity is summarized in the table 1. Keratopathy was more common with BM (p=0.004). Only 4 MEDI patients developed keratopathy, all grade 1 and associated with dry eyes and/or photophobia. In contrast, 60% of BM patients developed keratopathy (13% grade 3-4 keratopathy). The median time to keratopathy onset was 1 month with BM, and 2.8 with MEDI. The median time until keratopathy was 4.6 months for BM. Loss of best-corrected visual acuity (VA) was significantly more common with BM (p<0.001). The median time to any decline in VA was 1.5 months for BM and 2.3 for MEDI. The median time until VA returned to baseline was 2.4 months for BM and 2.3 for MEDI. The frequency of dose delays for ocular toxicity was comparable between ADCs, as was the number of dose reductions (16% BM vs. 12% MEDI, p=0.5). The most common reasons for treatment discontinuation were progression or death (BM=69%, MEDI=44%) and ocular toxicity (BM=18%, MEDI=30%). Conclusions: Treatment interruptions, dose reductions and drug discontinuation are common with BCMA directed ADC therapy. Further research to optimize the administration schedule of these agents is warranted. BM and MEDI produce distinct patterns of ocular side effects, namely keratopathy and reduced VA with the former, and photophobia and dry eyes with the latter. BM N = 68 MEDI N = 43 p-value 2 Prophylactic steroid eye drops 4 (6%) 28 (68%) <0.001 Prophylactic lubricant eye drops 42 (63%) 33 (80%) 0.051 Max grade keratopathy 0.004 1-2 29 (47%) 4 (19%) 3-4 8 (13%) 0 (0%) VA equal or worse than 20/40 26 (68%) 6 (20%) <0.001 Days of ADC treatment 59 (33, 167) 68 (41, 105) 0.9 Dose delay for ocular toxicity 19 (28%) 8 (19%) 0.2 n (%); Median (IQR); 2 Chisq test; Wilcoxon rank sum.

7541 Background: Multiple myeloma (MM) is characterized by recurrent cytogenetic abnormalities, including translocations involving the immunoglobulin heavy chain locus on chromosome 14 and trisomies, which are considered primary and clonal. Throughout disease progression, MM cells may acquire additional abnormalities, which include chromosome 1 abnormalities (gain or amplification of 1q or deletion of 1p) and chromosome 17 abnormalities (del 17p or monosomy 17p). All these factors are considered high-risk markers that predict below-average outcomes. While outcomes related to 1q have been documented, their relationship with other abnormalities and clinical characteristics is less clearly defined. Methods: We created a cohort of newly diagnosed MM (NDMM) patients from April 1996 to December 2023 for whom FISH testing was performed using a panel that included 1q findings. Data on clinical and laboratory characteristics, other FISH abnormalities, and survival outcomes were collected from existing databases and the electronic medical record (EMR). Results: The cohort included 875 patients, with a median age of 65. Of these patients, 60% were male and 91% identified as white. A 1q abnormality was observed in 443 patients (51%); 87% exhibited a gain of 1q, while 13% showed amplification of 1q. Among those tested, other abnormalities included del13 (58%), t(11;14) (25%), t(4;14) (17%), t(14;16) (6%), del 17p (13%), and trisomies (51%). The distribution of abnormalities concerning the presence of 1q is presented in the table. Patients with 1q abnormalities were more likely to present with additional high-risk cytogenetic abnormalities. The median overall survival (OS) for those with a 1q abnormality was 73 months, compared to 105 months for those without it. Among these, patients with 1q amplification tended to have worse outcomes than those with a 1q gain, though this observation did not reach statistical significance. Conclusions: Abnormalities of chromosome 1, including 1q gain and amplification, can be seen in nearly 50% of patients with NDMM who are tested. 1q abnormalities are associated with other high-risk cytogenetic abnormalities. Measures of disease burden are higher among those with a 1q abnormality. Interestingly, we observed a higher proportion of patients with lambda light chain and those with IgA among those with a 1q abnormality. The presence of a 1q abnormality was associated with inferior survival, with a trend towards worse outcomes among those with 1q amplification compared to 1q gain. Clinical characteristics and cytogenetic associations of multiple myeloma patients with and without 1q abnormalities. 1q abnormality present 1q abnormality absent P del13 78% 39% <0.01 t(4;14) 25% 8% <0.01 t(11;14) 22% 27% NS t(14;16) 15% 3% <0.01 Trisomies 48% 53% NS 17p del 24% 12% <0.01 Lambda light chain 45% 26% <0.01 IgA 32% 16% <0.01 Hemoglobin 10.3 g/dL 11.2 g/dL <0.01

7540 Background: The combination of a proteasome inhibitor (PI) with lenalidomide (R) and dex (d) has been a common initial therapy for newly diagnosed myeloma (NDMM). We designed a randomized phase 3 trial to examine if carfilzomib (K), a next generation PI, improved progression free survival (PFS) compared with bortezomib (V) when either is combined with Rd for initial treatment of NDMM. Initial analysis at a median follow up of 15.3 months (mos) showed comparable PFS for both triplets. We present the long-term results of the trial with ~70 months median follow up. Methods: Patients (Pts) with NDMM, were randomized 1:1 to receive VRd or KRd for 36 weeks followed by a 2 nd randomization (1:1) to indefinite versus 2 yrs of R maintenance. Pts without del17p, t(14;16), t(14;20), plasma cell leukemia or high-risk GEP70 profile, were enrolled. VRd arm included V 1.3 mg/m 2 on days(d) 1, 4, 8, and 11 (d1, 8 for cycles 9-12), R 25 mg d1-14, and d 20 mg d1, 2, 4, 5, 8, 9, 11, 12 of a 3-week (wk) cycle for 12 cycles, while pts in the KRd arm received K 36 mg/m 2 d1, 2, 8, 9, 15, 16 with R 25 mg daily on d1-21 and d 40 mg wkly, in 4 wk cycles for 9 cycles. Maintenance used 15 mg R d1-21 q4 wks. Results: The study accrued 1087 pts (VRd=542, KRd=545). Median age was 65y; baseline characteristics including intent to transplant were similar across the arms. Median induction duration (mos; IQR) was 7.2 (3.4-8.9) and 8.4 (5.1-9.1) for VRd and KRd, respectively; 59.8% in VRd and 45.3% in KRd did not proceed to Step 2. Median PFS (mos) was VRd=41.9 and KRd=44.6; HR = 0.89 (0.76-1.04). Toxicity data, PFS sensitivity analyses and OS probabilities are as in the table. Conclusions: In this randomized trial, with median follow up of nearly 6 years, KRd and VRd had comparable PFS and OS in an intent to treat analysis. While similar numbers proceeded to SCT in the 2 arms, more did so during induction in the VRd arm while more patients in the KRd arm went to SCT later. VRd remains a standard triplet induction regimen in standard and intermediate risk NDMM, and a suitable backbone for 4 drug combinations. Clinical trial information: NCT01863550 . N (%) VRd(n=527) KRd(n=526) SCT anytime 186 (34.3) 183 (33.6) SCT without Step 2 registration 146 112 Median Time to SCT (mos; range) 7.7 (3.5-83.9) 10.6 (3.7-70.6) Grade 3-4 Treatment-Related Toxicity 315 (59.8) 344 (65.4) Grade 5 Treatment-Related Toxicity 2 (0.4) 9 (1.7) Grade 5 All Events 11 (2.1) 20 (3.8) Survival outcomes HR Median (95% CI) Median (95% CI) PFS Primary: PD or death within 3 months of last evaluation as events 0.89(0.76-1.04) 41.9(35.7, 50.3) 44.6(38.2, 51.9) PFS Sensitivity: All deaths as events, 0.87(0.75-1.02) 39.5(34.9, 46.0) 42.8(37.4, 49.7) PFS Sensitivity: Censor at alternate Rx 0.83(0.69-0.99) 35.0(31.3, 42.6) 38.7(34.7, 49.0) PFS Sensitivity: Event at alternate Rx 0.84(0.73-0.97) 18.0(14.2, 23.0) 24.4(20.9, 27.9) Overall survival 0.92(0.75-1.12) 119(100, NE) 118(103-NE)

3069 Background: Molecular targeted agents have revolutionized cancer diagnosis and treatment. Intraoperative molecular imaging (IMI) is a novel technique that entails performing real-time, in vivo optical imaging during surgery to ensure cancer clearance. A multicenter clinical trial was conducted using abenacianine, a cathepsin targeted near-infrared (NIR) IMI agent to visualize pulmonary nodules during surgery. The primary objective was to assess the efficacy of abenacianine in localizing pulmonary lesions, evaluating surgical margin, and identifying unsuspected disease. Methods: Participants scheduled to undergo surgery for known or suspected cancer in the lung received abenacianine (0.32 mg/kg intravenous) preoperatively 12 to 36 hours before surgery. During a standard-of-care surgery, the lung underwent IMI and additional disease not identified by conventional methods were identified and analyzed. Efficacy was measured by frequency of clinically significant events (CSEs) defined as localization of lesions not found by standard surgical techniques, identification of additional cancers, identification of positive surgical margins confirmed by histology, and detection of cancerous lymph nodes. Results: 89 participants were included in the study. The mean age was 67 years and 57 (64%) were female. Of 89 participants administered abenacianine who underwent standard of care surgical resection for known or suspected cancer in the lung, 40 (45%) had at least one CSE. Abenacianine with NIR imaging identified lesions that were not found by standard surgical methods in 34 (38%) participants, synchronous and occult cancers that were not found by pre-operative imaging in 2 (2%), margins within 10 mm of the closest staple line in 8 (9%), and lymph nodes determined to be cancerous in 1 (1%) participant. Tumors visualized by IMI with abenacianine included non-small cell lung cancers (adenocarcinoma, squamous cell carcinoma, neuroendocrine tumor) and cancers that metastasized to the lung (breast, colorectal, prostate, thymoma, renal cell, sarcoma). Abenacianine was safe and well tolerated in this study; there were no drug-related serious adverse events. Conclusions: This Phase 2 multicenter study demonstrated that using IMI with abenacianine during standard-of-care lung cancer surgery markedly improved clinical outcomes. Abenacianine localized tumors intraoperatively, identified synchronous and occult lesions, helped assess negative margin status, and identified cancerous lymph nodes enabling a more complete oncologic resection. Clinical trial information: NCT06145048 .

9578 Background: Anti-PD1 immunotherapy has shown improved clinical outcomes in patients (pts) with advanced cSCC, and recently, in the neoadjuvant setting for resectable disease. Pathological (path) response is predictive of recurrence in melanoma and recent NeoIT trials suggests the same in cSCC; however, an analysis of clinical outcomes in pts with resectable cSCC treated with intended anti-PD1-based NeoIT in larger datasets remains unknown. Methods: Pts with resectable cSCC treated with intended anti-PD1-based NeoIT from 17 cancer centres globally were included. Baseline patient and disease characteristics, treatment regimen, path response and recurrence-free survival (RFS) or progression-free survival (PFS) were collected and examined. Results: 134 pts with resectable cSCC were treated with intended anti-PD1-based NeoIT. Median age was 75 years old (range, 39-97), 72% (n=97) were male. One fifth (22%, n=29) were immunocompromised and 43% (n=58) had ECOG PS of ≥1. Of 125 (93%) pts with known primary cSCC, 82% (n=102) were from the head & neck. Most pts (79%, n=106) were stage III/IV. The majority had anti-PD1 monotherapy (91%, n=122) and 9% (n=12) had anti-PD1+/-investigational agent. Median follow-up from commencement of NeoIT was 10 months (95% CI, 9 - 12). Nearly half of the pts (49%, n=66) underwent surgery; 37 (56%) pts had major pathological response (MPR; ≤10% viable tumour cells at the surgical specimen; 31 [47%] had complete path response [0% of viable tumour cells] and 6 [9%] had near complete path response [1-10% of viable tumour cells]), 6 (9%) had partial path response (pPR; >10% and ≤50% of viable tumour cells), and 23 (35%) had path non-response (pNR; >50% of viable tumour cells). Of the 66 pts who underwent surgery, 11% (n=7) had recurrence (5 loco-regional and 2 distant recurrence), all non-MPR pts (1 pPR and 6 pNR). 12-months RFS was improved with MPR vs non-MPR (100% vs 79%, p=0.004). 52% (n=34) pts had adjuvant treatment (23 anti-PD1 alone, 7 anti-PD1+/-investigational agent, 2 platinum and 2 cetuximab). Within non-MPR pts, 12 had adjuvant treatment (3 recurred; 25%), while 17 did not have adjuvant treatment (4 recurred; 24%). Fifty-one percent (n=68) of pts did not have surgery; 9 (13%) due to progressive disease (PD) and 53 (78%) due to clinical response. Of the 53 pts with a clinical response, 5 (9%) subsequently progressed. Fourteen (10%) pts have died, 6 (4%) related to cSCC; 2 had surgery (non-MPR) and 4 did not have surgery (all due to PD). Conclusions: Anti-PD1-based NeoIT is an active regimen in resectable stage II-IV cSCC and is associated with high clinical response and MPR rates. No pts with MPR from NeoIT has recurred to date, however, 9% of pts who did not have surgery due to clinical response eventually progressed. These findings highlight the importance of further research to investigate the role of surgery in this subgroup of patients.

OBJECTIVE Cervical spondylotic myelopathy (CSM) is often accompanied by neck pain, which, along with more recognized neurological deficits like motor and sensory changes, significantly impacts patients’ quality of life. The authors examined whether age influences improvements in neck disability and related quality-of-life measures after surgery for CSM. Using the Neck Disability Index (NDI) as the primary outcome, they compared long-term outcomes at 24 months among patients aged ≥ 65, ≥75, and < 65 years, exploring the effects of surgical intervention on both pain-related disability and functional recovery in older adults. METHODS Using the Quality Outcomes Database, the authors conducted a detailed propensity score–matched analysis on cohorts aged ≥ 65 and ≥ 75 years compared with a < 65-year-old cohort while controlling for baseline NDI scores, other demographic variables, health status, underlying pathology, number of levels, indication for surgery, surgical approach, and type of surgery. Differences in NDI total and subdomain scores at 24 months postoperatively were the primary measures of improvement. Age-related variability in NDI differential was assessed. EQ-5D and calculated SF-6D were secondary measures. RESULTS Of the 1141 patients in the cohort (January 2016 to December 2018), 687 patients were < 65 years, 325 were 65 to < 75 years, and 129 were ≥ 75 years of age. After propensity score matching, 197 patients each were well matched in the ≥ 65-year (mean 71.4 years) and < 65-year (mean 55.3 years) cohorts; similarly, 57 patients each were matched in the ≥ 75-year (mean 78.3 years) and < 65-year (mean 55.8 years) cohorts. Improvements in NDI scores and subdomain scores, EQ-5D, and calculated SF-6D were consistent at 3, 12, and 24 months postoperatively across all cohorts. At 24 months, patients ≥ 65 years showed NDI score improvements (−14.7 ± 22.3) similar to those < 65 years (−13.0 ± 21.3, p = 0.454), and patients ≥ 75 years demonstrated NDI improvements (−15.0 ± 19.7) comparable to those < 65 years (−17.6 ± 20.4, p = 0.499). A sensitivity analysis for linear relationship found that NDI improvement was statistically greater in older patients (7.5 points every 30 years, p < 0.0001), but this difference was below the minimal clinically important difference. Other clinical outcomes were similar between cohorts. CONCLUSIONS Surgical intervention for CSM yields substantial and similar improvements in NDI scores and other metrics among various age groups, including those aged at least 65 and 75 years. These results highlight the effectiveness of surgery across a broad patient demographic, underscoring its value in treating CSM irrespective of age.

Background Endovascular therapy (EVT) for stroke due to distal or medium vessel occlusion (DMVO) is safe. Due to the distinct anatomical characteristics of DMVOs, further evaluation of EVT is crucial to determine which devices may yield better outcomes. Methods A retrospective analysis of adults with DMVO treated in 37 centers (11 countries) was queried. The primary outcome of favorable shift in 90-day modified Rankin Scale (mRS) was compared between patients treated with Trevo versus other devices on first pass using 1:1 propensity score matching (PSM) with multivariable adjustment. Secondary outcomes included the number of pass attempts, final thrombolysis in cerebral infarction (TICI) score 2b-3, symptomatic intracranial hemorrhage (sICH), improvement in National Institutes of Health Stroke Scale (NIHSS) at 24h, and 90-day mortality. Results Of the 1115 included patients, 264 (24%) were treated with Trevo (PSM cohort of 261 per group). Trevo use was not associated with a favorable 90-day mRS shift (proportional odds ratio [OR] 1.10, 95% confidence interval [CI] 0.80–1.51). Trevo was associated with fewer passes (adjusted β=-0.25, 95% CI −0.48 - −0.03), higher odds of TICI 2b-3 (adjusted OR 1.97, 95% CI 1.11–3.49), and a greater 24h NIHSS improvement (adjusted β= −1.74, 95% CI −3.11 - −0.36), with no difference in sICH or mortality (p>0.05). Results were similar in sensitivity analyses. Conclusions We observed no safety concerns with Trevo as compared to other EVT devices for DMVO recanalization. There was a signal of better technical efficacy and early clinical improvement.