Citations

7547 Background: Minimal residual disease (MRD) has been recently accepted by the Food and Drug Administration (FDA) as an endpoint for accelerated approval in Multiple Myeloma. However, emerging data from recent trials were not included in previous analyses. While literature-based meta-analyses on the correlation between MRD and approved clinical outcomes typically require extensive manual review, leveraging AI with expert-in-the-loop validation can efficiently generate reliable evidence from comprehensive clinical studies with up-to-date outcomes. Methods: An AI-assisted framework was developed to identify relevant studies and extract critical information via two independent objectives. The first objective examined trial-level associations, modeling treatment effects on MRD and clinical endpoints across patient populations using weighted least squares, with association strength measured by coefficients of determination (R²) and 95% confidence intervals (CIs). The second objective analyzed individual-level associations using synthetic individual patient data (SynthIPD) generated from the published Kaplan-Meier plots and summary statistics of patient subgroups. Results: AI-assisted screening identified eligible studies (>50 patients per treatment arm) reporting progression-free survival (PFS), overall survival (OS), and MRD-negative complete response rates (MRD-CR rate) using multi-parameter next-generation flow cytometry or sequencing methods (sensitivity threshold ≥10⁻⁵), expanding previous analyses from 15 to 20 two-arm studies. Trial-level analysis demonstrated an R² of 0.69 (95% CI 0.50–0.89) for PFS log hazard ratio versus MRD-CR rate log odds ratio. Analysis of synthetic individual data from Kaplan-Meier curves using a novel digitization method yielded a global odds ratio of 7.28 (95% CI 5.60–8.95) for individual-level correlation between MRD-CR rates and PFS outcomes. Conclusions: This study validates MRD-CR rate as an endpoint for accelerated approval in MM through rapid AI-assisted literature review and synthetic individual patient data. The findings demonstrate moderate correlation between MRD-CR rate and median PFS at both trial and individual levels, consistent with previous literature but incorporating additional eligible studies. The novel SynthIPD approach presents an efficient alternative to traditional data-sharing methods while maintaining analytical robustness. These results align with current Oncologic Drugs Advisory Committee (ODAC) surrogacy analysis methods and support the utility of MRD assessment in MM clinical trials.

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)

7527 Background: Etentamig (etenta) is a differentiated BCMA x CD3 bispecific T-cell engager composed of high avidity bivalent BCMA-binding domains, low-affinity CD3-binding domain designed to reduce cytokine release syndrome (CRS), and silenced Fc tail for extended half-life enabling convenient dosing. We present long term results from 2 ongoing Ph 1 studies evaluating efficacy and safety of etenta in patients (pts) with RRMM. Methods: Data were from a Ph 1 multicenter, open-label, dose escalation/expansion (NCT03933735) trial and Arm A of a Ph 1b, open label (NCT05650632) trial of etenta; both enrolled pts ≥18 years with RRMM, ≥3 prior lines of therapy (LoT), and triple-class exposed. Pts received 60 mg Q4W or 40 mg Q3W, both regimens with similar dose intensity, in the Ph 1 trial; pts from Arm A of the Ph 1b trial received a step-up dose (SUD) on day 1 and full dose of 60 mg Q4W on day 4. This pooled analysis assessed long-term efficacy, safety, and tolerability. Tumor response was assessed per IMWG 2016 criteria. Results: Of 146 pts with RRMM who received etenta, 87 (60%) were male, median age (range) was 68 (40–87) years, median prior LoT were 4 (3–23), and median duration of follow-up was 13 (1–48) months (mo). ORR was achieved in 96 (66%) pts and ≥VGPR in 79 (54%) pts. Response rates across subgroups are reported in the Table. Median duration of response was not reached (NR) (NR–NR) among responders; Kaplan-Meier (KM) estimate at 12 mo was 71% (58.5%–80.5%). Median PFS (mPFS) was NR (8.7–NR) mo; KM estimate at 12 mo was 55% (44.9%–63.1%). Any grade and G3/4 treatment emergent adverse events (TEAEs) occurred in 145 (99%) pts and 116 (79%) pts. Most common G3/4 TEAEs (≥15%) were neutropenia (38%), anemia (23%), lymphopenia (25%), and thrombocytopenia (16%). Infections G3/G4 were reported in 32 (22%) pts; most common infections G3/G4 (≥5%) were pneumonia (12%) and sepsis (5%). TEAEs leading to etenta discontinuation were reported in 13 (9%) pts. Deaths from TEAEs were reported in 13 (9%) pts; 10 were not attributed to etenta treatment. In Arm A of Ph 1 study where 60mg Q4W was administered with SUD and modified dex as premedication, CRS incidence was 30% (4% G2; No ≥G3 events) with median time to CRS onset of 22.3 (5.5–29.6) hours; and median time to CRS resolution of 20.7 (1.8–131.7) hours. Conclusions: Etenta with SUD demonstrated a low CRS incidence, durable response, and tolerability in pts with heavily pretreated RRMM. Efficacy across all subgroups was comparable and maintained, suggesting therapeutic benefits among a broad population and supporting further exploration in the ongoing Ph 3 Cervino study. Subgroup ORR, n (%) ≥VGPR, n (%) mPFS, months (range) Age ≥75years 26 (72) 23 (63.9) NR (7.5–NR) Race: Black 15 (63) 13 (54.2) 13.7 (5.0–NR) High cytogenetic risk 21 (55) 18 (47.4) 7.4 (2.8–NR) 3 prior LoT 29 (64.4) 23 (51.1) 13.5 (5.6–NR) ≥4 prior LoT 67 (67) 56 (56) NR (8.3–NR)

7522 Background: Movement and neurocognitive treatment emergent adverse events (MNTs), cranial nerve palsies (CNPs) and immune-effector cell enterocolitis (IEC-EC) are late onset toxicities associated with cilta-cel and are associated with significant morbidity and mortality. We aimed to identify predisposing risk factors to allow for formulating risk-reduction strategies. Methods: Retrospective study of MM pts who received FDA approved cilta-cel at Mayo Clinic between Feb 2022-Dec 2024. Interrogated factors included demographics, disease and treatment characteristics, and selected lab values at different time points. In odds ratio (OR) analyses, pts were divided by toxicity type (1) No delayed toxicity (2) MNT (3) IEC-EC without MNT (4) isolated CNP. Differences between pts in the MNT, IEC-EC and CNP groups were compared separately in a pairwise manner vs. those with no delayed toxicity. Results: Of 235 pts, 26 (11%) had delayed toxicity [MNT = 8 (3%), IEC-EC = 9 (4%), CNP = 14 (6%)]; 3 pts had both MNT/IEC-EC and 2 had both CNP/IEC-EC. Median onset from CAR-T infusion for MNT, IEC-EC and CNP was 19 (range 8-96), 106 (35-169) and 21 (7-43) days respectively. Of 164 evaluable pts, those who had ICANS had increased odds for any delayed toxicity (OR 4.7; 95% CI 1.6-13.8). Pts who had ICANS (OR 7.7; 1.6-36.9), HLH/MAS (OR 6.2; 1.1-6.7) and Ferritin >400mcg/L at time of lymphodepletion (OR 6.3; 1.5-32) had increased odds for MNTs. Pts who received alkylator-based bridging therapy had increased odds (OR 6.1; 1.1-35) for IEC-EC. Analysis of serial post-CAR infusion lab values showed that peak ALC was the most significant variable with differences between groups shown in table. Median time to peak ALC was 12 days (IQR 11-13). ROC analysis determined peak ALC >3 x 10 9 /L as a meaningful cut point. Pts with peak ALC >3.0 x 10 9 /L had increased odds of developing any delayed toxicity (OR 9.3; 3.5-29.3), MNT and CNP (table). Absolute risk of any delayed toxicity was 33% in pts with peak ALC >3 x 10 9 /L vs 5% without. At this threshold, number needed to treat was 3.6. Conclusions: Real-world data shows that cilta-cel associated delayed toxicity is seen in ~10% of patients, with specific toxicity rates between 4-8%. Factors associated with these toxicities predominantly occur in the post CAR-T infusion period. Given that ALC expansion in the first 2 weeks correlate with CAR-T expansion, peak ALC is potentially predictive of toxicity and 3 x 10 9 /L may be an interventional threshold for primary prophylaxis. Peak ALC by toxicity groups. No ToxN=138 MNTN=8 CNPN=12 IEC-ECN=6 p value Peak ALC (10 9 /L), median (IQR) 1.8 (1.0-4.1) 6.2 (4.8-14.4) 4.3 (3.2-6.7) 3.6 (1.9-5.2) <0.001 1 ALC >3 x 10 9 /L, n (%) 43 (31%) 7 (88%) 10 (83%) 4 (67%) <0.001 2 Odd Ratios vs no Tox 3 , 95% CI 15.5 (2.6-293.7) 11.0 (2.8-73.9) 4.4 (0.8-25.0) 1 Wilcoxon/Kruskal-Wallis Tests, 2 Chi square test, 3 Logistic regression analysis.

TPS2695 Background: The SMARCB1/A4 gene products are core subunits of the SWItch/Sucrose Non Fermentable (SWI/SNF) chromatin remodeling complex. Tumors with defects in SWI/SNF are histologically distinct aggressive cancers occurring in children and young adults. SMARCB1/A4 deficient tumors, particularly malignant rhabdoid tumor (MRT), atypical teratoid rhabdoid tumor (ATRT), poorly differentiated chordoma (PDC), epithelioid sarcoma (ES), and renal medullary carcinoma (RMC), have immune cell infiltrates and programmed death ligand 1 (PD-L1) expression. Responses to immune checkpoint inhibition (CI) have been observed in SMARCB1/A4 deficient tumors; however, responses are not durable. T cell immunoreceptor with Ig and ITIM domains (TIGIT) is a novel inhibitory receptor expressed on multiple immune cells. TIGIT inhibits T and NK cells by binding to its ligand poliovirus receptor (PVR) and Nectin2 on both tumor and antigen-presenting cells. Utilizing RNAseq data, SMARCB1/A4 deficient tumors demonstrate high expression of PVR and Nectin2. Tiragolumab is an antibody to the TIGIT receptor. The combination of tiragolumab and atezolizumab has shown promising activity in early phase studies, and phase 3 studies are ongoing in multiple adult indications. Thus, there is rationale that the addition of tiragolumab to CI may also enhance response rates in patients with SMARCB1/A4 deficient tumors. Methods: This is a phase 1/2 trial of tiragolumab monotherapy (300 mg if ≤ 15 kg; 420 mg if > 15 kg to ≤ 40 kg; 600 mg if > 40 kg or ≥ 18 years) and in combination with atezolizumab (15 mg/kg [max 1200 mg]) if < 18 yrs or 1200 mg if ≥ 18 years) administered IV on Day 1 of 21-day cycles in patients > 12 months of age with SMARCB1/A4 deficient tumors. Part A evaluating the safety of tiragolumab monotherapy in patients < 18 years based on cycle 1 dose limiting toxicities is complete. Part B estimates the antitumor activity of tiragolumab in combination with atezolizumab in 6 histology-specific cohorts (RMC, MRT, ATRT, PDC, ES, and other SMARCB1/A4 deficient tumors) and is now open to all eligible age groups. Each cohort is conducted using a 6+4 Simon’s two stage design. Enrollment for each cohort is as follows: Part A 6/6, Part B RMC 1/6, MRT 1/6, ATRT 4/6, PDC 2/6, ES 3/6, other 6/6. Radiographic imaging central response assessment for the first stage of the “other” cohort is ongoing. Cycle 1 toxicities of the combination therapy are monitored in Part B patients < 12 yrs using a Bayesian Optimal INterval (BOIN) design with a target toxicity of 17%. Secondary objectives are to characterize the pharmacokinetics/anti-drug antibody development and to estimate progression free survival, overall survival, and duration of response. Enrollment is open at all Pediatric Early Phase Clinical Trial Network sites. Data cutoff: Jan 10, 2025. Clinical trial information: NCT05286801 .

e16052 Background: Patients with esophageal squamous cell carcinoma (ESCC) who fail definitive treatment are candidates for second-line therapy. They often present with more aggressive disease and suboptimal responses to definitive treatments. In this individual patient-level meta-analysis, we aim to evaluate the efficacy of PD-1/PD-L1 inhibitors as second-line treatment in advanced ESCC. Methods: A systematic search of PubMed, Scopus, and Cochrane databases (December 5, 2024) identified randomized controlled trials (RCTs) comparing PD-1/PD-L1 inhibitors to chemotherapy as second-line treatment for advanced ESCC. Kaplan-Meier (KM) curves were reconstructed, and individual patient data (IPD) were extracted using R scripts. A patient-level meta-analysis was performed using the reconstructed IPDs and the Cox proportional hazards regression model. The Schoenfeld residuals test and Restricted Mean Survival Time (RMST) were also applied. The following R packages were used: MASS, Splines, survival, survRM2, survminer, and dbplyr . Results: Out of 3,930 records, five RCTs met the criteria: four phase 3 trials and one phase 2 trial (ORIENT-2), all were open-label, comparing PD-1 inhibitors to chemotherapy. Overall survival (OS) improved significantly with PD-1/PD-L1 inhibitors compared to chemotherapy (HR: 0.718, 95% CI: 0.650–0.793, p < 0.001). For patients with CPS ≥ 10, OS further improved (HR: 0.626, 95% CI: 0.446–0.878, p = 0.007), ), indicating an additional beneft in those with high PD-1 expression. The proportional hazards assumption was met for both OS and CPS ≥ 10 (Schoenfeld residuals test: p > 0.05). Progression-free survival (PFS) showed no significant difference (HR: 0.913, CI: 0.828–1.007, p = 0.069). However, the proportional hazards assumption was violated (Schoenfeld residuals test p < 0.001); therefore, these results should be interpreted with caution. PFS was further evaluated using RMST at 6, 12, 18, and 24 months. At 6 months, no significant difference was observed (RMST difference: -0.047, p = 0.593). However, PD-1 inhibitors showed significant differences at 12 months (0.37 months, p = 0.022), 18 months (0.74 months, p = 0.001), and 24 months (0.97 months, p < 0.001). Despite these significant differences, the magnitude of the difference is relatively small and may not be clinically meaningful. Conclusions: PD-1/PD-L1 inhibitors as second-line therapy improve overall survival in patients with advanced esophageal squamous cell carcinoma, compared to chemotherapy. However, the improvements in progression-free survival (PFS) were modest, and the clinical significance of these PFS benefits may be limited.

e16076 Background: Gastric cancer is the fourth leading cause of global cancer deaths. Despite declining incidence and mortality, it remains a significant contributor to the global disease burden. This study analyzes regional gastric cancer DALYs and mortality trends from 1990-2021 using the GBD database. Methods: The regional DALYs and mortality rates per 100,000 individuals aged 70+ from GBD 2021 were analyzed, with trends from 1990 to 2021 evaluated using AAPC, and statistical significance assessed by p-values. Results: In 2021, the greatest Age-standardized DALYs rates were recorded in Andean Latin America, with 3068.04 per 100,000; the lowest was found in High-income North America with 386.08 per 100,000. The most significant increase of DALYs rate from 1990 to 2021 was in Southern Sub-Saharan Africa, (AAPC = -0.3068%; 95% CI: -0.3852 to -0.2234; p < 0.000001), while in Western Europe, the largest decline was noted (AAPC = -2.9999%; 95% CI: -3.0164 to -2.9841; p < 0.000001). Andean Latin America was the region with the highest Age-standardized mortality rates (ASMRs) in 2021, at 207.58 per 100,000 while High-income North America had the lowest at 27.18 per 100,000. In Western Sub-Saharan Africa, the ASMRs were rising with an AAPC of -0.2601% (95% CI: -0.2872 to -0.2368; p < 0.000001), while Western Europe had the highest decline with an AAPC of -2.7658% (95% CI: -2.7895 to -2.7471; p < 0.000001). Conclusions: The global burden of diseases from 1990 to 2021 is regional in nature. In 2021, DALYs and mortality were predominantly high in Andean Latin America and East Asia and notably low in High-income North America. DALYs have risen across Southern Sub-Saharan Africa over three decades, and mortality increased over Western Sub-Saharan Africa, while both declined sharply in Western Europe. These trends underscore the importance of regionalized health solutions. DALY per 100,000. Metric Region 1990 2021 AAPC (1990-2021) HIGHEST DISABILITY-ADJUSTED LIFE YEARS (DALYS) PER 100,000 Andean Latin America 4469.23 3068.04 -1.14 East Asia 5507.72 2958.98 -1.99 High Income Asia Pacific 4849.23 2130.43 -2.71 LOWEST DISABILITY-ADJUSTED LIFE YEARS (DALYS) PER 100,000 High Income North America 758.59 386.09 -2.22 Australasia 1116.91 567.32 -2.16 South Asia 794.81 680.50 -0.46 HIGHEST MORTALITY RATE PER 100,000 Andean Latin America 293.65 207.58 -1.04 East Asia 324.60 188.92 -1.72 High Income Asia Pacific 316.44 161.94 -2.22 LOWEST MORTALITY RATE PER 100,000 High Income North America 51.24 27.19 -2.02 Australasia 74.36 41.81 -1.85 South Asia 47.50 41.95 -0.39

e16074 Background: Gastric cancer is a malignant disease characterized by the uncontrolled growth of cells in the stomach lining. It is a global health concern with regional variation in incidence and prevalence. This study examines the national mortality trends in adults aged 70 years and older from 1990 to 2021. Methods: GBD data was analysed to assess the mortality rates of Gastric cancer in individuals aged ≥ 70 years. The Estimated Annual Percentage Change (EAPC) was used to evaluate trends from 1990 to 2021, with p-values determining statistical significance. Results: From 1990 to 2021, the global prevalence of Gastric cancer increased, peaking in 2021. Japan recorded the highest prevalence (621.7379, UI: 525.93, 675.74), followed by the Republic of Korea and China.In 2021, Bolivia (Plurinational State of) had the highest mortality rate (309.7, CI: 400.9, 240.6), slightly lower than its 1990 rate (445.35, CI: 539.58, 362.14), which was the highest that year. Mongolia (303.15, CI: 378.8, 226.2) and Cabo Verde (265.1, CI: 322.6, 206.8) followed. The lowest mortality rates were observed in Morocco (20.9, CI: 25.9, 15.0), Namibia (20.93, CI: 25.93, 16.4), and Nigeria (23.27, CI: 32.3, 19.2).Countries with the largest EAPC increases included Egypt (0.98, CI: 1.84, -0.22), Honduras (0.31, CI: 0.7, -0.01), and Lesotho (0.16, CI: 0.597, -0.16). The greatest declines were seen in Austria (-0.72, CI: -0.68, -0.74), Czechia (-0.69, CI: -0.64, -0.74), and Hungary (-0.67, CI: -0.607, -0.72). Conclusions: Mortality rates associated with Gastric Cancer among individuals aged 70 and older increased globally from 1990 to 2021, notably in Egypt, Honduras and Lesotho, emphasizing the need for improved prevention, management, and research on underlying disparities. Mortality percent changes. Metric Region 1990 2021 EAPC with 95% CI (1990-2021) HIGHEST MORTALITY PERCENT CHANGE Egypt 30.43 60.44 0.98 (1.84, -0.22) Honduras 140.76 184.48 0.31 (0.7, -0.01) Lesotho 77.18 90.26 0.16 (0.59, -0.16) LOWEST MORTALITY PERCENT CHANGE Austria 177.25 49.48 -0.72 (-0.68, -0.74) Czechia 168.73 51.51 -0.69 (-0.64, -0.74) Hungary 184.88 60.55 -0.67 (0.607, -0.72)

e16072 Background: Gastric cancer is a leading cause of mortality worldwide, with pronounced variations in outcomes across populations. This study investigates U.S. trends in age-adjusted mortality rates (AAMRs) for gastric cancer from 1999 to 2023, examining differences by gender, race, region, and urbanization to uncover critical patterns and inequities. Methods: Data were extracted from the CDC WONDER database using ICD-10 code C16 to identify gastric cancer-related deaths in adults aged 25 and older. AAMRs per 1,000,000 population were calculated and stratified by year, gender, race/ethnicity, geographic region, and urban-rural classification. Trends were analyzed using Joinpoint regression to determine annual percentage changes (APC) and 95% confidence intervals (CI). Statistical significance was set at p < 0.05. Results: From 1999 to 2023, there were 312,300 gastric cancer deaths (185,391 men, 126,909 women). Overall, AAMRs declined consistently, with APCs of -3.4 for the period 1999 to 2007, -2.2 for 2007 to 2018, and -1.2 for 2018 to 2023. Men showed a more pronounced decline, with APCs of -3.6 for 1999 to 2009 and -2.2 for 2009 to 2023, compared to women, who had APCs of -3.1 for 1999 to 2008, -1.9 for 2008 to 2018, and -0.8 for 2018 to 2023. Non-Hispanic Black populations experienced a decline in AAMR with an APC of -3.3 for 1999 to 2020, while Hispanic/Latino and Asian/Pacific Islander populations showed declines with APCs of -2.8 for 1999 to 2011 and -3.8 for 1999 to 2020, respectively. Metropolitan areas saw AAMR reductions with APCs of -3.3 for 1999 to 2008 and -2.2 for 2008 to 2020, while non-metropolitan areas had larger initial declines with an APC of -3.6 for 1999 to 2006 but slower decreases with an APC of -2.0 for 2006 to 2020. Geographically, the Northeast had the highest AAMR (62.9), followed by the West (61.7), South (57.4), and Midwest (50.9). Hawaii recorded the highest state-level AAMR (96.5), while Wyoming had the lowest (36.6). States in the top 90th percentile included Alaska, California, and New York, whereas Utah, Idaho, and Iowa were among the lowest. Conclusions: Gastric cancer mortality in the U.S. has declined over the past two decades, but the pace of reduction has slowed in recent years. Significant disparities persist across gender, racial, and geographic groups, underscoring the need for targeted interventions to address these inequities and improve outcomes in vulnerable populations.