Abstract 6638: Real-World evidence of eflapegrastim (efla) usage in patients with gastrointestinal (GI) malignancies.

Abstract Background: Long-acting granulocyte colony-stimulating factors (GCSFs) such as efla and pegfilgrastim (peg) are routinely used to prevent neutropenia in patients (pts) with cancer undergoing neutropenia-inducing chemotherapy. Registration studies compared efla to peg in pts with breast cancer; efla use in GI cancers is not as well characterized. We used real-world data to assess demographics, comorbidities, and clinical outcomes in pts receiving efla or peg and undergoing chemotherapy for various GI malignancies. Methods: We conducted a retrospective, cross-sectional cohort analysis of pts with GI cancers (ie, malignant neoplasm of the anus, biliary tract, colon, rectum, esophagus, gall bladder, stomach, liver/intrahepatic ducts, pancreas, or small intestine) who received ≥1 dose of efla or peg with chemotherapy. Information was extracted from electronic health records of 60 million US pts in the Atropos Health Apollo data source (v1. 1. 0) between 2023 and 2025. Clinical outcomes measured through 15 (D15) and 30 (D30) days post-GCSF included febrile neutropenia (FN), absolute neutrophil count (ANC), platelet count, and adverse events (AEs; thrombocytopenia, back and bone pain, myalgia, GI and nontraumatic head bleeding, acute respiratory distress syndrome, and localized skin reaction). Results: Pts (N=3353) receiving chemotherapy were identified (efla, n=106; peg, n=3247). Cancer types (5%) in the efla and peg groups included pancreatic (36% each), colon (27% each), esophagus (10% vs 7%), rectum/rectosigmoid (9% vs 18%), gastric (8% vs 9%), and liver/intrahepatic ducts (7% vs 9%). Chemotherapy regimens included FOLFIRI (35% vs 21%) and FOLFOX (48% vs 34%). Pts receiving efla were older and had a higher burden of comorbidities than those receiving peg: mean (SD) age was 70. 5 (8. 3) vs 64. 9 (12. 3) y, respectively, and mean (SD) Charlson Comorbidity Index score was 12. 0 (4. 0) vs 10. 5 (4. 3), respectively. FN incidence was similar between pts receiving efla or peg through D15 (0. 9% vs 1. 3%) and D30 (0. 9% vs 1. 8%), with higher mean ANC observed with efla vs peg: 10. 6 vs 6. 4 x 10⁹/L, respectively, through both D15 and D30. Thrombocytopenia occurred more frequently with efla than with peg (9. 4% vs 7. 8% through D15, 16. 0% vs 11. 0% through D30), with lower mean platelet counts through D15 (173 vs 216 x 10³/μL) and D30 (188 vs 219 x 10³/μL). Similar, low rates of AEs were reported through D30 with efla and peg. Conclusions: Pts receiving chemotherapy for GI malignancies who were treated with efla were older and had a higher burden of comorbidities than those treated with peg. The incidence of FN was similar and low between treatments. Other AEs were also comparable between the two groups. These real-world findings suggest the safety and efficacy of efla in adult pts with GI malignancies receiving diverse chemotherapy regimens. Citation Format: Howard Franklin, Jeffrey Crawford, John H. Baird, Kenneth Crist, Vincent Marino, Neil Shah, Lee S. Schwartzberg. Real-World evidence of eflapegrastim (efla) usage in patients with gastrointestinal (GI) malignancies abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (7 Suppl): Abstract nr 6638.