A randomized study of conventional chemotherapy +/- uproleselan in older adults with Acute Myeloid Leukemia eceiving intensive induction chemotherapy (Alliance A041701)

Abstract Background. Uproleselan (GMI-1271) is an antagonist of E-selectin, an adhesion molecule expressed on endothelial cells in the vascular niche of the bone marrow. Engagement of E-selectin by acute myeloid leukemia (AML) blasts, which express E-selectin ligand, activates cell survival pathways and promotes resistance to chemotherapy. In multiple preclinical AML tumor models, blockade of E-selectin with uproleselan enhanced the efficacy of chemotherapy. Methods. We conducted a phase (P) 2/3 study in which subjects age ≥ 60 years with untreated, FLT3 unmutated AML were randomized to receive conventional chemotherapy with or without uproleselan. Induction chemotherapy consisted of 7+3 (cytarabine + daunorubicin) +/- uproleselan with a second induction cycle with 5+2 +/- uproleselan administered for residual AML. Uproleselan 800 mg IV was administered as a single dose 24 hours before the first dose of chemotherapy and then every 12 hours until 48 hours after the completion of chemotherapy. Post-remission therapy consisted of up to 3 cycles intermediate-dose cytarabine 2 gm/m2 IV d1-5 +/- uproleselan. Allogeneic transplant was performed at the discretion of the treating physician. The primary endpoint was event-free survival (EFS) for P2 and overall survival (OS) for P3. Results. The study enrolled 267 patients between March 2019 and November 2021, with a median age of 66.9 years (IQR 63.8-69.9). 32% were classified as 2017 ELN intermediate risk, 41% as adverse risk, with 62 (29%) having complex karyotype / mutated TP53. The P2 analysis was to be performed when at least 191 events were observed. However, as the required events had not been observed > 5 years after study initiation and 3 years after completion of P2 enrollment, an independent statistician was consulted, and the analysis plan was amended to conduct the P2 EFS analysis in November 2024. With a median follow-up of 53.1 months, the EFS was not significantly different between the two arms (HR 0.90, 95% CI 0.70-1.23, P=0.58). As the study did not meet its P2 EFS endpoint, enrollment in the P3 was not initiated. There was no significant difference in OS between the 2 arms (HR 0.99, p=0.94) with a median OS in the uproleselan arm of 23.6 months (95% CI 15.1-35.4 mo) vs 19.8 months (14.6-36.3) for the control arm. The overall rate of CR/CRi after induction was 65% (CR: 60%) in the uproleselan arm versus 63% (CR: 55%) in the control. MRD results by either local or central assessment in patients achieving a CR/CRi were available for 129 patients with the MRDneg rate of 81 % (95% CI 69.5-89.9%) in the uproleselan arm vs 67% (54.3-78.4%) in the control arm (p=0.053), The 30-day mortality was 5.3% for uproleselan vs 8.1% in the control. Forty-eight (36%) patients in the uproleselan arm and 55 (40%) in the control arm underwent alloHCT, including 37 (27%) and 29 (22%) in CR1, respectively (p = 0.34). In patients undergoing alloHCT in CR1, those randomized to uproleselan and allografted in CR1 had an HR 0.71 (95% CI 0.34-1.47; P=0.35) compared to the control arm. Expression of E-selectin ligand on AML blasts was performed by flow cytometry, with subjects having an E-selectin ligand expression above the median having a trend towards worse median OS 16.2 (95% CI 11.4-24.3) vs 32.2 (15.9-57.8) months, but was not affected by treatment arm. In both univariate and multivariate analyses, WBC at baseline, ELN genetic risk group, and TP53/complex karyotype were found to be associated with EFS. A subgroup analysis identified an improvement in EFS favoring uproleselan in patients with mutated ASXL1 (HR 0.25, 95% CI 0.08-0.78, p<0.017). Conclusions. Although the addition of uproleselan to intensive chemotherapy was associated with a higher rate of MRDneg CR/CRi in older adults with AML, uproleselan failed to improve EFS or OS and did not overcome the adverse outcomes associated with higher E-selectin expression on AML blasts. The median OS of 20-24 months with an overall 3-year OS of almost 40% for patients treated on this study exceeds previous CALGB / US Cooperative Group studies (median OS ~12 months, 3-year OS ~20%) and continues to support a role for intensive chemotherapy in the management of older adults with AML. Furthermore, this study suggests a potential benefit for uproleselan in patients harboring ASXL1 mutations, which may warrant further investigation. ClinicalTrials.gov Identifier: NCT03701308