Day One Biopharmaceuticals announces three-year follow-up data from FIREFLY-1

Day One Biopharmaceuticals (DAWN) announced three-year results from the OJEMDA pivotal Phase 2 FIREFLY-1 trial in an oral presentation at the 30th Annual Meeting & Education Day of the Society for Neuro-Oncology. New data from the ongoing FIREFLY-1 trial, with an updated median study duration of 40.6 months, are described below. Primary trial results, including trial eligibility, patient demographics, efficacy and safety have been previously reported. In 76 evaluable patients from Arm 1, 44 completed 26 or more cycles of treatment. Amongst the key primary endpoints, the overall response rate was 53%, the median duration of response was 19.4 months, and the time to response was 5.4 months. The pre-specified secondary study endpoint of Progression Free Survival was evaluated by Response Assessment in Pediatric Neuro-Oncology Low-Grade Glioma. The median was 16.6 months. Exploratory analyses were also undertaken to further assess the clinical impact of tovorafenib in the same study population. Among these analyses: The median time-to-next-treatment was 42.6 months. 39 patients entered a treatment-free observation period: 77% were treatment-free for a minimum of 12 months. Median treatment-free interval, measured from the end of tovorafenib primary treatment to the start of the next subsequent anticancer treatment or death, was not reached. Tumor rebound was minimal in the first 6 months off therapy, with 31% of patients experiencing a greater than or equal to25% increase in tumor size from the last scan prior to the last dose. Eight patients received retreatment with tovorafenib: The median retreatment duration was 9 months. The median maximum percentage change in tumor reduction was -38.3%. In this updated three-year analysis, no new safety signals were identified. Grade 3 or higher adverse events most commonly reported were decreased growth velocity, anemia, blood creatine phosphokinase increased, maculopapular rash, alanine aminotransferase increased. Tovorafenib is approved by the U.S. Food and Drug Administration for the treatment of pediatric patients 6 months of age and older with relapsed or refractory pediatric low-grade glioma harboring a BRAF fusion or rearrangement.