GlycoMimetics, Inc. announced the U.S. Food and Drug Administration (FDA) cleared the addition of a protocol amendment to the company's pivotal Phase 3 study of uproleselan for relapsed/refractory (R/R) Acute Myeloid Leukemia (AML). The amendment will allow a time-based analysis of the primary endpoint of overall survival to be conducted following a defined cutoff date if the 295 survival events originally planned for an event driven analysis have not been observed. With the addition of a time-based analysis, topline results are expected to be reported by the end Second Quarter 2024.

The Phase 3 trial completed enrollment of 388 patients across 70 sites in nine countries in November 2021. An event based final analysis of overall survival was previously expected after year end 2022, but the number of events has slowed, resulting in the projected timeline being extended. Based on blinded pooled data observed to date, a time-based final analysis in Second Quarter 2024 is expected to yield a clinically mature dataset to evaluate uproleselan in R/R AML.

This dataset is expected to reflect a median follow-up of greater than three years, including at least two years of post-transplant data. The majority of surviving patients in the study received hematopoietic stem cell transplantation (HSCT). As a result, the company believes the capture rate of survival events for this study beyond Second Quarter 2024 would provide limited additional value for the primary analysis.

Two years post-transplant is generally considered an important milestone in AML because most patients who survive at least two years post-transplant without experiencing disease relapse are typically deemed to be long-term survivors. For patients over two years post-transplant, disease relapse is less likely. As part of the protocol amendment, the FDA also cleared the addition of landmark EFS and overall survival analyses as secondary endpoints.