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Aprea's Eprenetapopt Fails to Meet Primary Endpoint in Phase III Trial of TP53-Mutant MDS

NEW YORK – Aprea Therapeutics on Monday said that its investigational therapy eprenetapopt failed to improve outcomes as a front-line treatment for patients with TP53-mutant myelodysplastic syndromes.

Specifically, in a Phase III, registrational clinical trial eprenetapopt plus azacitidine did not significantly increase the complete remission rate in patients compared to just azacitidine. There were 154 patients in the trial, and those treated with the combination achieved a complete remission rate of 33 percent versus 22 percent among those who received azacitidine alone. The addition of the investigational agent, therefore, did increase the rate of complete remission marginally, but this figure did not reach statistical significance.

The addition of eprenetapopt to azacitidine likewise did not significantly improve the overall response rate and duration of response in patients compared to azacitidine. The median overall survival was similar between the two treatment arms at the time of data cutoff.

The experimental treatment combination was safe and tolerable, mirroring what was seen in earlier trials, and Aprea has said that it will present more information on the study findings at a future date with longer patient follow-up. Patients on the experimental treatment arm who have not yet achieved complete remission will remain on the clinical trial and their outcomes will be factored into future statistical analyses.

"Though we are disappointed the topline results did not reach statistical significance, we continue to believe that eprenetapopt can offer clinical benefit to patients with TP53-mutant malignancies," Eyal Attar, Aprea's CMO, said in a statement. "We will continue to analyze data as it matures and follow patients who are still receiving study treatment. Our other clinical trials continue to progress, and we remain committed to pursuing our clinical development programs."

Boston-based Aprea is also evaluating eprenetapopt as a treatment for TP53-mutant acute myeloid leukemia and will begin a Phase I clinical trial evaluating another investigational treatment, APR-548, for TP53-mutant myelodysplastic syndromes. The company has said that enrollment in this latter trial is anticipated to begin in early 2021.